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| 1 | SINGULAR PERTURBATION FOR A CLASS OF NONLINEAR REACTION DIFFUSION SYSTEMS显示文摘This paper deals with the initial-bounndary value problem for the wider nonlinear reaction diffusion system: where Leading into the variables of multiple scales, we obtained a uniformly valid asymptotic solution to any degree of precision by using comparison theorem. | 莫嘉琪 | 1989 | Science China Mathematics1989，32，11： | 213 |
| 2 | THE SINGULARLY PERTURBED PROBLEM FOR COMBUSTION REACTION DIFFUSION显示文摘A singularly perturbed combustion reaction diffusion Robin boundary value problem is considered. Using the theory of differential ineaqality, the existence of solution to the problem is proved and the asymptotic estimation of the solution is obtained. | 莫嘉琪 | 2001 | Acta Mathematicae Applicatae Sinica2001，17，2： | 68 |
| 3 | Diffusion weighted imaging in the liver显示文摘Diffusion weighted magnetic resonance imaging (DWI) is an imaging technique which provides tissue contrast by the measurement of diffusion properties of water molecules within tissues. Diffusion is expressed in an apparent diffusion coefficient (ADC), which reflects the diffusion properties unique to each type of tissue. DWI has been originally used in neuroradiology. More recently, DWI has increasingly been used in addition to conventional unenhanced and enhanced magnetic resonance imaging (MRI) in other parts of the body. The reason for this delay was a number of technical problems inherent to the technique, making DWI very sensitive to artifacts, which had to be overcome. With assessment of ADC values, DWI proved to be helpful in characterization of focal liver lesions. However, DWI should always be used in conjunction to conventional MRI since there is considerable overlap between ADC values of benign and malignant lesions. DWI is useful in the detection of hepatocellular carcinoma in the cirrhotic liver and detection of liver metastases in oncological patients. In addition, DWI is a promising tool in the prediction of tumor responsiveness to chemotherapy and the follow-up of oncological patients after treatment, as DWI may be capable of detecting recurrent disease earlier than conventional imaging.This review focuses on the most common applications of DWI in the liver. | Petra G Kele Eric J van der Jagt | 2010 | World Journal of Gastroenterology2010，16，13： | 48 |
| 4 | Evaluation of diffusion weighted imaging of magnetic resonance imaging in small focal hepatic lesions:a quantitative study in 56 cases显示文摘Diffusion-weighted imaging (DWI) as a new technique of magnetic resonance imaging (MRI) is used to detect focal hepatic lesions. This study was designed to evaluate the significance of DWI to differentiate focal hepatic lesions less than 3 cm in diameter by the quantitation of apparent diffusion coefficient (ADC) values. METHODS:DWI using 1.5T MRI scanner unit was performed with a spin-echo single-shot echo planar imaging (EPI) in 56 cases of small focal hepatic lesions, including hepatocellular carcinoma (11), hepatic metastatic tumor (15 ), hepatic cavernous hemangioma (14), and hepatic cyst (16).The ADC values of these lesions were calculated respectively. The ratios of the ADC values of lesion/liver in hepatocellular carcinomas and hepatic metastatic tumors were also estimated. RESULTS:The mean ADC values (mm2/s) were (0.93±0.06) ×10-3 in hepatocellular carcinomas, (1.09±0.18)×10-3 in hepatic metastatic tumors,(1.95±0.38)×10-3 in hepatic cavernous hemangiomas, and (3.18±0.33) ×10-3 in hepatic cysts. The ratios of ADC values of lesion/liver were 0.90±0.06 and 1.15±0.14 in hepatocellular carcinoma and hepatic metastatic tumors respectively, which were significantly different (P<0.05). CONCLUSION:The measurement of ADC values and the ratios of ADC values of lesion/liver are helpful in MR diagnosis and differentiation of focal hepatic lesions. | Xian-Yue Quan, Xi-Jie Sun, Zhi-Jian Yu and Ming Tang Imaging Center, Affiliated Zhujiang Hospital of Southern Medical University, Guangzhou 510282, China | 2005 | Hepatobiliary & Pancreatic Diseases International2005，4，3： | 39 |
| 5 | A CLASS OF SINGULARLY PERTURBED REACTION DIFFUSION INTEGRAL DIFFERENTIAL SYSTEM显示文摘In this paper a class of singularly perturbed initial boundary value problems for the reaction diffusion integral differential system are considered. Using the iteration method and the differential inequalities, the existence, uniqueness and its asymptotic behavior of solution for the initial boundary value problems are studied. | 莫嘉琪 | 1999 | Acta Mathematicae Applicatae Sinica1999，15，1： | 31 |
| 6 | THE NONLINEAR SINGULARLY PERTURBED PROBLEMS FOR REACTION DIFFUSION EQUATIONS WITH TIME DELAY显示文摘A class of nonlinear for singularly perturbed problems for reaction diffusion equations with time delays are considered. Under suitable conditions, using theory of differential inequalities the asymptotic behavior of solution for the initial boundary value problems are studied. | 莫嘉琪 冯茂春 | 2001 | Acta Mathematica Scientia2001，21，2： | 31 |
| 7 | Broadband diffusion of terahertz waves by multi-bit coding metasurfaces显示文摘The terahertz region is a special region of the electromagnetic spectrum that incorporates the advantages of both microwaves and infrared light waves.In the past decade,metamaterials with effective medium parameters or gradient phases have been studied to control terahertz waves and realize functional devices.Here,we present a new approach to manipulate terahertz waves by using coding metasurfaces that are composed of digital coding elements.We propose a general coding unit based on a Minkowski closed-loop particle that is capable of generating 1-bit coding(with two phase states of 0 and 180°),2-bit coding(with four phase states of 0,90°,180°,and 270°),and multi-bit coding elements in the terahertz frequencies by using different geometric scales.We show that multi-bit coding metasurfaces have strong abilities to control terahertz waves by designing-specific coding sequences.As an application,we demonstrate a new scattering strategy of terahertz waves—broadband and wide-angle diffusion—using a 2-bit coding metasurface with a special coding design and verify it by both numerical simulations and experiments.The presented method opens a new route to reducing the scattering of terahertz waves. | Li-Hua Gao Qiang Cheng Jing Yang Shao-Jie Ma Jie Zhao Shuo Liu Hai-Bing Chen Qiong He Wei-Xiang Jiang Hui-Feng Ma Qi-Ye Wen Lan-Ju Liang Biao-Bing Jin Wei-Wei Liu Lei Zhou Jian-Quan Yao Pei-Heng Wu Tie-Jun Cui | 2015 | Light(Science & Applications)2015，4，1： | 31 |
| 8 | Colorectal cancer:Current imaging methods and future perspectives for the diagnosis, staging and therapeutic response evaluation显示文摘In the last 10 years the mortality rate of colorectal cancer(CRC)has decreased by more than 20%due to the rising developments in diagnostic techniques and optimization of surgical,neoadjuvant and palliative therapies.Diagnostic methods currently used in the evaluation of CRC are heterogeneous and can vary within the countries and the institutions.This article aims to discuss in depth currently applied imaging modalities such as virtual computed tomography colonoscopy,endorectal ultrasound,computed tomography(CT)and magnetic resonance imaging(MRI)in the diagnosis of CRC.Special focus is put on the potential of recent diagnostic developments as diffusion weighted imaging MRI,MRI biomarkers(dynamic enhanced MRI),positron emission tomography with 2-(fluorine-18)-fluoro-2-deoxy-D-glucose(FDG-PET)combined with computed tomography(PET/CT)and new hepatobiliary MRI contrast agents.The precise role,advantage and disadvantages of these modalities are evaluated controversially in local staging,metastatic spread and treatment monitoring of CRC.Finally,the authors will touch upon the future perspectives in functional imaging evaluating the role of integrated FDG-PET/CT with perfusion CT,MRI spectroscopy of primary CRC and hepatic transit time analysis using contrast enhanced ultrasound and MRI in the detection of liver metastases.Validation of these newer imaging techniques may lead to significant improvements in the management of patients with colorectal cancer. | Maka Kekelidze Luigia D'Errico Michele Pansini Anthony Tyndall Joachim Hohmann | 2013 | World Journal of Gastroenterology2013，19，46： | 28 |
| 9 | Diffusion kurtosis imaging of microstructural changes in brain tissue affected by acute ischemic stroke in different locations显示文摘The location of an acute ischemic stroke is associated with its prognosis. The widely used Gaussian model-based parameter, apparent diffusion coefficient(ADC), cannot reveal microstructural changes in different locations or the degree of infarction. This prospective observational study was reviewed and approved by the Institutional Review Board of Xiamen Second Hospital, China(approval No. 2014002).Diffusion kurtosis imaging(DKI) was used to detect 199 lesions in 156 patients with acute ischemic stroke(61 males and 95 females), mean age 63.15 ± 12.34 years. A total of 199 lesions were located in the periventricular white matter(n = 52), corpus callosum(n = 14), cerebellum(n = 29), basal ganglia and thalamus(n = 21), brainstem(n = 21) and gray-white matter junctions(n = 62). Percentage changes of apparent diffusion coefficient(ΔADC) and DKI-derived indices(fractional anisotropy [ΔFA], mean diffusivity [ΔMD], axial diffusivity [ΔD_a], radial diffusivity ΔDr, mean kurtosis [ΔMK], axial kurtosis [ΔK_a], and radial kurtosis [ΔK_r]) of each lesion were computed relative to the normal contralateral region. The results showed that(1) there was no significant difference in ΔADC, ΔMD, ΔD_a or ΔD_r among almost all locations.(2) There was significant difference in ΔMK among almost all locations(except basal ganglia and thalamus vs. brain stem; basal ganglia and thalamus vs. gray-white matter junctions; and brainstem vs. gray-white matter junctions.(3) The degree of change in diffusional kurtosis in descending order was as follows: corpus callosum > periventricular white matter > brainstem > gray-white matter junctions > basal ganglia and thalamus > cerebellum. In conclusion, DKI could reveal the differences in microstructure changes among various locations affected by acute ischemic stroke, and performed better than diffusivity among all groups. | Liu-Hong Zhu Zhong-Ping Zhang Fu-Nan Wang Qi-Hua Cheng Gang Guo | 2019 | Neural Regeneration Research2019，14，2： | 26 |
| 10 | Contribution of diffusion,perfusion and functional MRI to the disconnection hypothesis in subcortical vascular cognitive impairment显示文摘Vascular cognitive impairment(VCI)describes all forms of cognitive impairment caused by any type of cerebrovascular disease.Early identification of VCI is quite difficult due to the lack of both sensitive and specific biomarkers.Extensive damage to the white matter tracts,which connect the cortical and subcortical regions,has been shown in subcortical VCI(SVCI),the most common subtype of VCI that is caused by small vessel disease.Two specific MRI sequences,including diffusion tensor imaging(DTI)and functional MRI(fMRI),have emerged as useful tools for identifying subtle white matter changes and the intrinsic connectivity between distinct cortical regions.This review describes the advantages of these two modalities in SVCI research and the current DTI and fMRI findings on SVCI.Using DTI technique,a variety of studies found that white matter microstructural damages in the anterior and superior areas are more specific to SVCI.Similarly,functional brain abnormalities detected by fMRI have also been mainly shown in anterior brain areas in SVCI.The characteristic distribution of brain abnormalities in SVCI interrupts the prefrontal-subcortical loop that results in cognitive impairments in particular domains,which further confirms the‘disconnection syndrome’hypothesis.In addition,another MRI technique,arterial spin labelling(ASL),has been used to describe the disconnection patterns in a variety of conditions by measuring cerebral blood flow.The role of the ASL technique in SVCI research is also assessed.Finally,the review proposes the application of multimodality fusion in the investigation of SVCI pathogenesis. | Qing Ye Feng Bai | 2018 | Stroke & Vascular Neurology2018，3，3： | 20 |
| 11 | Diffusion weighted imaging: Technique and applications显示文摘Diffusion weighted imaging(DWI) is a method of signal contrast generation based on the differences in Brownian motion. DWI is a method to evaluate the molecular function and micro-architecture of the human body. DWI signal contrast can be quantified by apparent diffusion coefficient maps and it acts as a tool for treatment respon-se evaluation and assessment of disease progression. Ability to detect and quantify the anisotropy of diffusion leads to a new paradigm called diffusion tensor imaging(DTI). DTI is a tool for assessment of the organs with highly organised fibre structure. DWI forms an integral part of modern state-of-art magnetic resonance imaging and is indispensable in neuroimaging and oncology. DWI is a field that has been undergoing rapid technical evolution and its applications are increasing every day. This review article provides insights in to the evolution of DWI as a new imaging paradigm and provides a summary of current role of DWI in various disease processes. | Vinit Baliyan Chandan J Das Raju Sharma Arun Kumar Gupta | 2016 | World Journal of Radiology2016，8，9： | 18 |
| 12 | Prediction of different stages of rectal cancer: Texture analysis based on diffusion-weighted images and apparent diffusion coefficient maps显示文摘BACKGROUND It is evident that an accurate evaluation of T and N stage rectal cancer is essential for treatment planning.It has not been extensively investigated whether texture features derived from diffusion-weighted imaging(DWI)images and apparent diffusion coefficient(ADC)maps are associated with the extent of local invasion(pathological stage T1-2 vs T3-4)and nodal involvement(pathological stage N0 vs N1-2)in rectal cancer.AIM To predict different stages of rectal cancer using texture analysis based on DWI images and ADC maps.METHODS One hundred and fifteen patients with pathologically proven rectal cancer,who underwent preoperative magnetic resonance imaging,including DWI,were enrolled,retrospectively.The ADC measurements(ADCmean,ADCmin,ADCmax)as well as texture features,including the gray level co-occurrence matrix parameters,the gray level run-length matrix parameters and wavelet parameters were calculated based on DWI(b=0 and b=1000)images and the ADC maps.Independent sample t-tests or Mann-Whitney U tests were used for statistical analysis.Multivariate logistic regression analysis was conducted to establish the models.The predictive performance was validated by receiver operating characteristic curve analysis.RESULTS Dissimilarity,sum average,information correlation and run-length nonuniformity from DWIb=0 images,gray level nonuniformity,run percentage and run-length nonuniformity from DWIb=1000 images,and dissimilarity and run percentage from ADC maps were found to be independent predictors of local invasion(stage T3-4).The area under the operating characteristic curve of the model reached 0.793 with a sensitivity of 78.57%and a specificity of 74.19%.Sum average,gray level nonuniformity and the horizontal components of symlet transform(SymletH)from DWIb=0 images,sum average,information correlation,long run low gray level emphasis and SymletH from DWIb=1000 images,and ADCmax,ADCmean and information correlation from ADC maps were identified as independent predictors of nodal involvement.The area under the operating characteristic curve of the model reached 0.802 with a sensitivity of 80.77%and a specificity of 68.25%.CONCLUSION Texture features extracted from DWI images and ADC maps are useful clues for predicting pathological T and N stages in rectal cancer. | Jian-Dong Yin Li-Rong Song He-Cheng Lu Xu Zheng | 2020 | World Journal of Gastroenterology2020，26，17： | 15 |
| 13 | 在尖锐 ischemic 击的磁性的回声散开灌注失配: 更改显示文摘 The concept of magnetic resonance perfusion-diffusion mismatch(PDM) provides a practical and approximate measure of the tissue at risk and has been increasingly applied for the evaluation of hyperacute and acute stroke in animals and patients.Recent studies demonstrated that PDM does not optimally define the ischemic penumbra;because early abnormality on diffusion-weighted imaging overestimates the infarct core by including part of the penumbra,and the abnormality on perfusion weighted imaging overestimates the penumbra by including regions of benign oligemia.To overcome these limitations,many efforts have been made to optimize conventional PDM.Various alternatives beyond the PDM concept are under investigation in order to better define the penumbra.The PDM theory has been applied in ischemic stroke for at least three purposes:to be used as a practical selection tool for stroke treatment;to test the hypothesis that patients with PDM pattern will benefit from treatment,while those without mismatch pattern will not;to be a surrogate measure for stroke outcome.The main patterns of PDM and its relation with clinical outcomes were also briefly reviewed.The conclusion was that patients with PDM documented more reperfusion,reduced infarct growth and better clinical outcomes compared to patients without PDM,but it was not yet clear that thrombolytic therapy is beneficial when patients were selected on PDM.Studies based on a larger cohort are currently under investigation to further validate the PDM hypothesis. | Feng Chen Yi-Cheng Ni | 2012 | World Journal of Radiology2012，4，3： | 14 |
| 14 | Enhancing aerodynamic performances of a high-turning compressor cascade via boundary layer suction显示文摘Experimental investigation was carried out to study the effect of suction positions and suction flow rates on the aerodynamic performance of a compressor cascade with a large camber angle. The ink-trace flow visualization was conducted and the flow fields of the cascade were also measured. Three types of boundary layer suction configurations are compared,i.e. the suction surface suction,the endwall suction and the compound suction. Experimental results show that the large amount of suction flow rate gains more losses reduction than the small amount for a certain proper suction configuration,but the speed of loss decline slows down as the suction flow rate goes on increasing. Boundary layer suction on the suction surface obviously enhances the ability of the boundary layer around the midspan to withstand the negative pressure gradient of the flow passage. The range of the suction surface corner is also decreased. If the suction slot locates in the corner separation region where severe separation has happened,the flow separation will be terminated at the slot and redevelop downstream. And boundary layer suction on the endwall mainly influences the endwall corner region in remarkably delaying,lessening and reorganizing the corner separation. While the whole flow field is remarkably improved at both midspan and the corner region in the compound suction schemes. At higher suction flow rates,the aerodynamic performance of the compressor cascade is better than that with boundary layer suction simply on the suction surface or on the endwall. When the suction flow rate is 1.5% of the inlet mass flow,the compound suction scheme achieves a maximum loss reduction of 17% compared with the cascade without boundary layer suction. | GUO Shuang1, CHEN ShaoWen1, LU HuaWei2, SONG YanPing1 & CHEN Fu1 1 School of Energy Science and Engineering, Harbin Institute of Technology, Harbin 150001, China 2 Marine Engineering College, Dalian Maritime University, Dalian 116026, China | 2010 | Science China(Technological Sciences)2010，53，10： | 14 |
| 15 | Optimal nonlinear feedback control of quasi-Hamiltonian systems显示文摘An innovative strategy for optimal nonlinear feedback control of linear or nonlinear stochastic dynamic systems is proposed based on the stochastic averaging method for quasi-Hamiltonian systems and stochastic dynamic programming principle. Feedback control forces of a system are divided into conservative parts and dissipative parts. The conservative parts are so selected that the energy distribution in the controlled system is as requested as possible. Then the response of the system with known conservative control forces is reduced to a controlled diffusion process by using the stochastic averaging method. The dissipative parts of control forces are obtained from solving the stochastic dynamic programming equation. | 朱位秋 应祖光 | 1999 | Science China Mathematics1999，42，11： | 14 |
| 16 | Attractors for a Nonclassical Diffusion Equation显示文摘Abstract For a nonclassical diffusion equation,the asymptotic behavior is investigated,and the existence ofa global attractor is proved. | Yue-long XiaoDepartment of Mathematics, Xiangtan University, Xiangtan 411105, China | 2002 | Acta Mathematicae Applicatae Sinica2002，18，2： | 14 |
| 17 | DIFFUSION COUPLE BETWEEN HIGHSTRENGTH WEAR-RESISTING ALUMINUM BRONZE AND MACHINING TOOLS MATERIALS显示文摘INTRODUCTIONAluminumbronzeisanimportantengineeringmaterial.Itsexcelentphysical,mechanical,anticorosionandwearresistingprop... | Li, Yuanyuan Zhang, Datung Ngai Tungwai, Leo Xia, Wei Long, Yan | 1999 | 中国有色金属学会会刊:英文版1999，9，1： | 14 |
| 18 | Three-dimensional bioprinting collagen/silk fibroin scaffold combined with neural stem cells promotes nerve regeneration after spinal cord injury显示文摘Many studies have shown that bio-scaffolds have important value for promoting axonal regeneration of injured spinal cord.Indeed,cell transplantation and bio-scaffold implantation are considered to be effective methods for neural regeneration.This study was designed to fabricate a type of three-dimensional collagen/silk fibroin scaffold (3D-CF) with cavities that simulate the anatomy of normal spinal cord.This scaffold allows cell growth in vitro and in vivo.To observe the effects of combined transplantation of neural stem cells (NSCs) and 3D-CF on the repair of spinal cord injury.Forty Sprague-Dawley rats were divided into four groups: sham (only laminectomy was performed),spinal cord injury (transection injury of T10 spinal cord without any transplantation),3D-CF (3D scaffold was transplanted into the local injured cavity),and 3D-CF + NSCs (3D scaffold co-cultured with NSCs was transplanted into the local injured cavity.Neuroelectrophysiology,imaging,hematoxylin-eosin staining,argentaffin staining,immunofluorescence staining,and western blot assay were performed.Apart from the sham group,neurological scores were significantly higher in the 3D-CF + NSCs group compared with other groups.Moreover,latency of the 3D-CF + NSCs group was significantly reduced,while the amplitude was significantly increased in motor evoked potential tests.The results of magnetic resonance imaging and diffusion tensor imaging showed that both spinal cord continuity and the filling of injury cavity were the best in the 3D-CF + NSCs group.Moreover,regenerative axons were abundant and glial scarring was reduced in the 3D-CF + NSCs group compared with other groups.These results confirm that implantation of 3D-CF combined with NSCs can promote the repair of injured spinal cord.This study was approved by the Institutional Animal Care and Use Committee of People’s Armed Police Force Medical Center in 2017 (approval No.2017-0007.2). | Ji-Peng Jiang Xiao-Yin Liu Fei Zhao Xiang Zhu Xiao-Yin Li Xue-Gang Niu Zi-Tong Yao Chen Dai Hui-You Xu Ke Ma Xu-Yi Chen Sai Zhang | 2020 | Neural Regeneration Research2020，15，5： | 14 |
| 19 | Abdominal applications of diffusion-weighted magnetic resonance imaging: Where do we stand?显示文摘Diffusion-weighted imaging (DWI) is one of the magnetic resonance imaging (MRI) sequences providing qualitative as well as quantitative information at a cellular level. It has been widely used for various applications in the central nervous system. Over the past decade, various extracranial applications of DWI have been increasingly explored, as it may detect changes even before signal alterations or morphological abnormalities become apparent on other pulse sequences. Initial results from abdominal MRI applications are promising, particularly in oncological settings and for the detection of abscesses. The purpose of this article is to describe the clinically relevant basic concepts of DWI, techniques to perform abdominal DWI, its analysis and applications in abdominal visceral MR imaging, in addition to a brief overview of whole body DWI MRI. | Ajaykumar C Morani Khaled M Elsayes Peter S Liu William J Weadock Janio Szklaruk Jonathan Russell Dillman Asra Khan Thomas L Chenevert Hero K Hussain | 2013 | World Journal of Radiology2013，5，3： | 12 |
| 20 | Antibacterial activities of selected medicinal plants in traditional treatment of human wounds in Ethiopia显示文摘Objective:To evaluate the activity of selected Ethiopian medicinal plants traditionally used for wound treatment against wound-causing bacteria.Methods:Samples of medicinal plants(Achyranthes aspera,Brucea antidysenteriea,Datura stramonium,Croton macrostachyus,Acokanthera xchimperi.,Phytolacca dodecandra,Milhttia ferruginea,and Solanum incanum)were extracted using absolute methanol and water and tested for their antimicrobial activities against clinical isolates and standard strains of wound-causing bacteria using agar well diffusion and micro titer plate methods.Results:Most of the plant extracts had antibacterial activities,among which Acokanthera schimperi and Brucea antidysenteriea inhibited growth of 100%and 35%of the test organisms,respectively.Methanolic extracts had higher activities compared with their corresponding aqueous extracts.The most susceptible organism to the extracts was Streptococcus pyogens while the most resistant were Escherichia coli and Proteus vulgaris.Conclusions:This finding justifies the use of the plants in wound healing and their potential activity against woundcausing bacteria.Their toxicity level and antimicrobial activity with different extraction solvents should further be studied to use them as sources and templates for the synthesis of drugs to control wound and other disease-causing bacteria. | Biruhalem Taye Mirutse Giday Abebe Animut Jemal Seid | 2011 | Asian Pacific Journal of Tropical Biomedicine2011，1，5： | 12 |
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