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| 1 | A Two-Step Shape-Preserving Advection Scheme显示文摘This paper proposes a new two-step non-oscillatory shape-preserving positive definite finite difference advection transport scheme, which merges the advantages of small dispersion error in the simple first-order upstream scheme and small dissipation error in the simple second-order Lax-Wendroff scheme and is completely different from most of present positive definite advection schemes which are based on revising the upstream scheme results. The proposed scheme is much less time consuming than present shape-preserving or non-oscillatory advection transport schemes and produces results which are comparable to the results obtained from the present more complicated schemes. Elementary tests are also presented to examine the behavior of the scheme. | 宇如聪 | 1994 | Advances in Atmospheric Sciences1994，11，4： | 43 |
| 2 | The Constrained Solutions of Two Matrix Equations | An Ping LIAO Zhong Zhi BAI Department of Mathematics. Hunan University. Changshu, 410082. P. R. China Department of Mathematics and Information Science, Changsha University, Changsha 410003. P. R. China Academy of Mathematics and System. Sciences. Chinese Academy of Sciences. Beijing 100080. P. R. China State Key Laboratory of Scientific/Engineering Computing. Chinese Academy of Sciences. Institute of Computational Mathematics and Scientific/Engineering Computing. Academy of Mathematics and System Sciences. Chinese Academy of Sciences. P. O. Box 2719. Beijing 100080. P. R. China | 2002 | Acta Mathematica Sinica,English Series2002，18，4： | 40 |
| 3 | ON THE EXISTENCE OF POSITIVE SOLUTIONS TO SECOND ORDER PERIODIC BVPS显示文摘The existence of positive solutions to second-order periodic BVPs-u'+Mu =j(t, u),t(0) = u(2π),u’(0) = '(2π) and u'+ Mu = I(t, u), u(0) = u(2π), u’(0) = u’(2π)is proved by a simple appliCation of a Fixed point Theorem in cones due to Krasnoselskii. | 蒋达清 | 1998 | Acta Mathematica Scientia1998，18，S1： | 28 |
| 4 | Lightning activity and precipitation structure of hailstorms显示文摘By using the cloud-to-ground (CG) lightning location data from the lightning detection network of He- nan Province, surface Doppler radar data and standard orbit data of PR, TMI and LIS on TRMM satellite, the spatial and temporal characteristics of CG lightning flashes in 10 severe hailstorms are analyzed. The results show that the percentage of +CG lightning in these hailstorms is high with an average value of 45.5%. There is a distinct increase in CG flash rate during the rapid development stage of hailstorms. The hailstone falling corresponds to an active positive flash period, and the increase of +CG flash rate is generally accompanied with a decrease of –CG flash rate. The flash rate declines rapidly during the dissipating stage of hailstorms. The precipitation structure and lightning activity in two typical hail- storms are studied in detail. It is found that strong convective cells with reflectivity greater than 30dBZ mainly are situated in the front region of hailstorms, whereas the trailing stratiform region is in the rear part of the hailstorms. The maximum heights of echo top are higher than 14 km. Convective rain con- tributes much more rainfall to the total than stratiform rain, and the convective rain takes about 85% and 97% of the total in the two cases, respectively. Total lightning in the hailstorms is very active with the flash rate up to 183 fl/min and 55 fl/min, respectively. The results also indicate that most lightning flashes occurred in the echo region greater than 30 dBZ and its immediate periphery. The probability of lightning occurrence is 20 times higher in the convective region than in the stratiform region. The result suggests that the lightning information is helpful to the identification of convective rain region. The linear relationship between flash rate and ice water content is disclosed primarily. | FENG GuiLi1,2, QIE XiuShu3,1, YUAN Tie1 & NIU ShuZhen4 1 Laboratory of Lightning and Thunderstorm, Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences, Lanzhou 730000, China 2 Shandong Research Institute of Meteorology, Jinan 250031, China 3 Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China 4 The Meteorological Observatory of Henan Province, Zhengzhou 450003, China | 2007 | Science China Earth Sciences2007，50，4： | 22 |
| 5 | 一种基于聚类的PU主动文本分类方法显示文摘文本分类是信息检索的关键问题之一.提取更多的可信反例和构造准确高效的分类器是PU(positive and unlabeled)文本分类的两个重要问题.然而,在现有的可信反例提取方法中,很多方法提取的可信反例数量较少,构建的分类器质量有待提高.分别针对这两个重要步骤提供了一种基于聚类的半监督主动分类方法.与传统的反例提取方法不同,利用聚类技术和正例文档应与反例文档共享尽可能少的特征项这一特点,从未标识数据集中尽可能多地移除正例,从而可以获得更多的可信反例.结合SVM主动学习和改进的Rocchio构建分类器,并采用改进的TFIDF(term frequency inverse document frequency)进行特征提取,可以显著提高分类的准确度.分别在3个不同的数据集中测试了分类结果(RCV1,Reuters-21578,20 Newsgoups).实验结果表明,基于聚类寻找可信反例可以在保持较低错误率的情况下获取更多的可信反例,而且主动学习方法的引入也显著提升了分类精度. | 刘露 彭涛 左万利 戴耀康 | 2013 | 软件学报2013，24，11： | 23 |
| 6 | Hierarchical and probabilistic quantum state sharing via a non-maximally entangled stateHierarchical and probabilistic quantum state sharing via a non-maximally entangled stateHierarchical and probabilistic quantum state sharing via a non-maximally entangled state显示文摘A scheme that probabilistically realizes hierarchical quantum state sharing of an arbitrary unknown qubit state with a four-qubit non-maximally entangled 丨X) state is presented in this paper. In the scheme, the sender Alice distributes a quantum secret with a Bell-state measurement and publishes her measurement outcomes via a classical channel to three agents who are divided into two grades. One agent is in the upper grade, while the other two agents are in the lower grade. Then by introducing an ancillary qubit, the agent of the upper grade only needs the assistance of any one of the other two agents for probabilistically obtaining the secret, while an agent of the lower grade needs the help of both the other two agents by using a controlled-NOT operation and a proper positive operator-valued measurement instead of the usual projective measurement. In other words, the agents of two different grades have different authorities to reconstruct Alice's secret in a probabilistic manner. The scheme can also be modified to implement the threshold-controlled teleportation. | 彭家寅 柏明强 莫智文 | 2014 | Chinese Physics B2014，，1： | 20 |
| 7 | Recruitment maneuvers in acute respiratory distress syndrome: The safe way is the best way显示文摘Acute respiratory distress syndrome(ARDS) represents a serious problem in critically ill patients and is associated with in-hospital mortality rates of 33%-52%. Recruitment maneuvers(RMs) are a simple, low-cost, feasible intervention that can be performed at the bedside in patients with ARDS. RMs are characterized by the application of airway pressure to increase transpulmonary pressure transiently. Once non-aerated lung units are reopened, improvements are observed in respiratory system mechanics, alveolar reaeration on computed tomography, and improvements in gas exchange(functional recruitment). However, the reopening process could lead to vascular compression, which can be associated with overinflation, and gas exchange may not improve as expected(anatomical recruitment). The purpose of this review was to discuss the effects of different RM strategies- sustained inflation, intermittent sighs, and stepwise increases of positive end-expiratory pressure(PEEP) and/or airway inspiratory pressure- on the following parameters: hemodynamics, oxygenation, barotrauma episodes, and lung recruitability through physiological variables and imaging techniques. RMs and PEEP titration are interdependent events for the success of ventilatory management. PEEP should be adjusted on the basis of respiratory system mechanics and oxygenation. Recent systematic reviews and meta-analyses suggest that RMs are associated with lower mortality in patients with ARDS. However, the optimal RM method(i.e., that providing the best balance of benefit and harm) and the effects of RMs on clinical outcome are still under discussion, and further evidence is needed. | Raquel S Santos Pedro L Silva Paolo Pelosi Patricia RM Rocco | 2015 | World Journal of Critical Care Medicine2015，4，4： | 19 |
| 8 | Urbanization: positive and negative effects显示文摘Urbanization is a sign of modernization,and both developed and developing countries attach great importance to this issue.It is also a process in which the population continues to flow in urban areas,the non-agricultural industries(manufacturing and seivice industries)concentrate and develop,and the structure of human society gradually transforms.Urbanization drives economic development.changes the urban form,and in fluences production technologies,citizen lifestyles,and societal values.However,urbanization can have negative impacts on social equity,public health,and the natural environment.Leveraging the positive effects of urbanization while mitigating the negative effects is necessary for sustaining urban progress and improving human settlements.Otherwise,the'urban disease'and regional inequalities caused by urbanization will become increasingly severe,especially in rapidly urbanizing countries. | Chaolin Gu | 2019 | Science Bulletin2019，64，5： | 17 |
| 9 | Contrast-enhanced ultrasound improved performance of breast imaging reporting and data system evaluation of critical breast lesions显示文摘AIM: To determine whether contrast-enhanced ultrasound(CEUS) can improve the precision of breast imaging reporting and data system(BI-RADS) categorization. METHODS: A total of 230 patients with 235 solid breast lesions classified as BI-RADS 4 on conventional ultrasound were evaluated. CEUS was performed within one week before core needle biopsy or surgical resection and a revised BI-RADS classification was assigned based on 10 CEUS imaging characteristics. Receiver operating characteristic curve analysis was then conducted to evaluate the diagnostic performance of CEUS-based BI-RADS assignment with pathological examination as reference criteria. RESULTS: The CEUS-based BI-RADS evaluation classified 116/235(49.36%) lesions into category 3, 20(8.51%), 13(5.53%) and 12(5.11%) lesions into categories 4A, 4B and 4C, respectively, and 74(31.49%) into category 5. Selecting CEUS-based BI-RADS category 4A as an appropriate cut-off gave sensitivity and specificity values of 85.4% and 87.8%, respectively, for the diagnosisof malignant disease. The cancer-to-biopsy yield was 73.11% with CEUS-based BI-RADS 4A selected as the biopsy threshold compared with 40.85% otherwise, while the biopsy rate was only 42.13% compared with 100% otherwise. Overall, only 4.68% of invasive cancers were misdiagnosed.CONCLUSION: This pilot study suggests that evaluation of BI-RADS 4 breast lesions with CEUS results in reduced biopsy rates and increased cancer-to-biopsy yields. | Jun Luo Ji-Dong Chen Qing Chen Lin-Xian Yue Guo Zhou Cheng Lan Yi Li Chi-Hua Wu Jing-Qiao Lu | 2016 | World Journal of Radiology2016，8，6： | 17 |
| 10 | EXISTENCE AND GLOBAL ATTRACTIVITY OF POSITIVE PERIODIC SOLUTION OF A LOGISTIC GROWTH SYSTEM WITH FEEDBACK CONTROL AND DEVIATING ARGUMENTS显示文摘In this paper, we study the existence and global attractivity of positive peri- odic solutions of a Logistic growth system with feedback control and deviating arguments. A sufficient condition is derived for the existence of a unique peri- odic solution with strictly positive components which is globally asymptotically stable by using the method of coincidence degree and Liapunov functional. Some new results are obtained. The known results are improved and generalized. | 杨帆 蒋达清 | 2001 | Annals of Differential Equations2001，17，4： | 17 |
| 11 | On the infimum problem of Hilbert space effects显示文摘The quantum effects for a physical system can be described by the set ε(H) of positive operators on a complex Hilbert space Hthat are bounded above by the identity operator Ⅰ. The infimum problem of Hilbert space effects is to find under what condition the infimum A∧B exists for two quantum effects A and B ∈ε(H). The problem has been studied in different contexts by R. Kadison, S. Gudder, M. Moreland, and T. Ando. In this note, using the method of the spectral theory of operators, we give a complete answer of the infimum problem. The characterizations of the existence of infimum A ∧ B for two effects A, B ∈ε(H) are established. | DU Hongke DENG Chunyuan LI Qihui | 2006 | Science China Mathematics2006，49，4： | 16 |
| 12 | POSITIVE SOLUTIONS OF FOURTH-ORDER TWO-POINT BOUNDARY VALUE PROBLEMS显示文摘We study the existence of positive solutions of the equation f(x, y(x),y'(x)) =0 with either y(0)= y(1) =y'(0) = y'(1) =0 or y(0) = y’(1)=y'(0) = y'(1) = 0. We show the existence of at least one positive solution if f is either superlinear of sublinear by a simple application of a fixed point theorem In cones. | 马如云 | 1999 | Annals of Differential Equations1999，15，3： | 16 |
| 13 | Existence and global attractivity of a positive periodic solution of a class of delay differential equation显示文摘The existence and the global attractivity of a positive periodic solution of the delay differential equation y·(t)=y(t)F[t, y(t-τ 1(t)),...,y(t-τ n(t))] are studied by using some techniques of the Mawhin coincidence degree theory and the constructing suitable Liapunov functionals. When these results are applied to some special delay bio-mathematics models, some new results are obtained, and many known results are improved. | 李永昆 | 1998 | Science China Mathematics1998，41，3： | 15 |
| 14 | Diagnostic accuracy of endoscopic ultrasound in pancreatic neuroendocrine tumors: A systematic review and meta analysis显示文摘AIM: To detect pancreatic neuroendocrine tumors (PNETs) has been varied. This study is undertaken to evaluate the accuracy of endoscopic ultrasound (EUS) in detecting PNETs.METHODS: Only EUS studies confirmed by surgery or appropriate follow-up were selected. Articles were searched in Medline, Ovid journals, Medline nonindexed citations, and Cochrane Central Register of Controlled Trials and Database of Systematic Reviews. Pooling was conducted by both fixed and random effects model). RESULTS: Initial search identified 2610 reference articles, of these 140 relevant articles were selected and reviewed. Data was extracted from 13 studies (n = 456) which met the inclusion criteria. Pooled sensitivity of EUS in detecting a PNETs was 87.2% (95%CI: 82.2-91.2). EUS had a pooled specificity of 98.0% (95%CI: 94.3-99.6). The positive likelihood ratio of EUS was 11.1 (95%CI: 5.34-22.8) and negative likelihood ratio was 0.17 (95%CI: 0.13-0.24). The diagnostic odds ratio, the odds of having anatomic PNETs in positive as compared to negative EUS studies was 94.7 (95%CI: 37.9-236.1). Begg-Mazumdar bias indicator for publication bias gave a Kendall's tau value of 0.31 (P = 0.16), indication no publication bias. The P for χ2 heterogeneity for all the pooled accuracy estimates was > 0.10. CONCLUSION: EUS has excellent sensitivity and specificity to detect PNETs. EUS should be strongly considered for evaluation of PNETs. | Srinivas R Puli Nikhil Kalva Matthew L Bechtold Smitha R Pamulaparthy Micheal D Cashman Norman C Estes Richard H Pearl Fritz-Henry Volmar Sonu Dillon Michael F Shekleton David Forcione | 2013 | World Journal of Gastroenterology2013，19，23： | 14 |
| 15 | A REGULARIZED CONJUGATE GRADIENT METHOD FOR SYMMETRIC POSITIVE DEFINITE SYSTEM OF LINEAR EQUATIONS显示文摘AbstractA class of regularized conjugate gradient methods is presented for solving the large sparse system of linear equations of which the coefficient matrix is an ill-conditioned symmetric positive definite matrix. The convergence properties of these methods are discussed in depth, and the best possible choices of the parameters involved in the new methods are investigated in detail. Numerical computations show that the new methods are more efficient and robust than both classical relaxation methods and classical conjugate direction methods. | Zhong-zhi Bai Shao-liang Zhang | 2002 | Journal of Computational Mathematics2002，20，4： | 13 |
| 16 | POSITIVE SOLUTIONS OF SINGULAR SUBLINEAR SECOND ORDER BOUNDARY VALUE PROBLEMS显示文摘This paper mainly studies the existence of positive solutions of singular sub-linear boundary value problems concerning the generalized Emden-Fowler equations. Anecessary and sufficient condition for the existence of positive solutions to this problemhas been obtained by using the method of lower and upper solutions with the fixed poilltt heorems. | WEI Zhongli(Department of Fundamental Courses, Shandong Arehitectuml andCivil Engineering Institute, Ji’nan 250014, China) | 1998 | Systems Science and Mathematical Sciences1998，11，1： | 12 |
| 17 | Existence of solutions and positive solutions to a fourth-order two-point BVP with second derivative显示文摘Several existence theorems were established for a nonlinear fourth-order two-point boundary value problem with second derivative by using Leray-Schauder fixed point theorem, equivalent norm and technique on system of integral equations. The main conditions of our results are local. In other words, the existence of the solution can be determined by considering the height of the nonlinear term on a bounded set. This class of problems usually describes the equilibrium state of an elastic beam which is simply supported at both ends. | 姚庆六 | 2004 | Journal of Zhejiang University-Science A(Applied Physics & Engineering)2004，5，3： | 12 |
| 18 | The Harmonious Dissipative Operators and the Completely Square Conservative Difference Scheme in an Explicit Way显示文摘In this paper, a new definition on harmonious dissipative operators is given and some important properties of theirs are shown. Especially, the relationship between a harmonious dissipative operator and the completely square conservative difference scheme in an explicit way is revealed. Kinds of 2-order, 3-order and 4-order harmonious dissipative operators are constructed by using the traditional Runge-Kutta method and a species of general m-order harmonious dissipative operators is established in the linear case. In addition, an efficiency parameter to appraise the time benefits of a harmonious dissipative operator is defined in this paper. It is testified in numerical tests that the harmonious dissipative operators are indeed able to improve the time-efficiency and computational effect of the completely square conservative difference scheme in an explicit way. | 王斌 季仲贞 | 1994 | Science China Chemistry1994，37，4： | 11 |
| 19 | Positive aspects of caregiving in schizophrenia: A review显示文摘Schizophrenia is a severe mental illness which is associated with significant consequences for both the patients and their relatives. Due to chronicity of the illness, the relatives of patients of schizophrenia have to bear the main brunt of the illness. Studies across the world have evaluated various aspects of caregiving and caregivers such as burden, coping, quality of life, social support, expressed emotions, and psychological morbidity. In general the research has looked at caregiving as a negative phenomenon, however, now it is increasingly recognised that caregiving is not only associated with negative consequences only, also experience subjective gains and satisfaction. This review focus on the conceptual issues, instruments available to assess the positive aspects of caregiving and the various correlates of positive aspects of caregiving reported in relation to schizophrenia. The positive aspect of caregiving has been variously measured as positive caregiving experience, caregiving satisfaction, caregiving gains and finding meaning through caregiving scale and positive aspects of caregiving experience. Studies suggests that caregivers of patients with schizophrenia and psychotic disorders experience caregiving gains(in the form of becoming more sensitive to persons with disabilities, clarity about their priorities in life and a greater sense of inner strength), experience good aspects of relationship with the patient, do have personal positive experiences. Some of the studies suggest that those who experience greater negative caregiving experience also do experience positive caregiving experience. | Parmanand Kulhara Natasha Kate Sandeep Grover Ritu Nehra | 2012 | World Journal of Psychiatry2012，2，3： | 10 |
| 20 | Continuous Positive Airway Pressure Effectively Alleviates Arrhythmias in Patients with Obstructive Sleep Apnea:Possible Relationship with Counteracting Oxidative Stress显示文摘This work is aimed at exploring the clinical efficacy of continuous positive airway pressuie(CPAP)in treatment of patients with arrhythmias combined with obstructive sleep apnea(OSA).Through evaluating serum native thiol,malonaldehyde(MDA)and nicotinamide adenine dinucleotide phosphate oxidase(NADPH oxidase)in these patients and describing the effects on oxidative parameters of CPAP therapy for 3 months,we confirmed the impact of oxidative stress on arrhythmias.A total of 64 patients with OSA combined with arrhythmias were collected from April 2014 to April 2017 with full clinical information.Patients were divided into two groups(paired experiment design):32 patients in group A(control group),who received unchanged anti-arrhythmia treatment and 32 patients in group B,who were subjected to unchanged pharmacological anti-arrhythmia therapy combined with CPAP.OSA related parameters were compared between the two groups after 3-month therapy.And the levels of parameters of oxidative stress in patients were measured before and after CPAP therapy.After 3 months of CPAP therapy,compared with the control group,the percentage of sage N3(NREM 3)and stage R(REM)in total sleep time was significantly increased,while apnea-hypopnea index(AHI)and the Epworth Sleepiness Scale(ESS)score were evidently decreased.Meanwhile,the lowest oxygen saturation(LSpCh)was also elevated after CPAP treatment for 3 months.The CPAP therapy significantly prevented the occurrence of arrhythmias(P<0.05).Both the MDA level and NADPH oxidase levels were significantly lower in the group B than in the group A(P<0.05).But serum native thiol was improved by CPAP treatment(P<0.05).In conclusion,proper use of CPAP therapy provides significant benefits for the treatment of arrhythmia in patients with OSA. | Xiao-ting WANG Gang ZHAO Ling TU Zhi-yong YUE Zhen-hua LIU Jie HAN Kun GAO Xuan-chen ZHOU Shuai XU Jian-feng LI | 2019 | Current Medical Science2019，39，1： | 10 |
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