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    题名 作者 年代 出处 被引量
1Paleoclimatic significance of grain size of loess-palaeosol deposit in Chinese Loess Plateau显示文摘Particle size analysis for samples from three last glacial cycle loess_palaeosol profiles along a northwest_southeast transection on the Chinese Loess Plateau has been carried out. The paleoclimatic significance of grain size indices has been obtained by analyzing the fraction content variations and their comparisons with global ice volume and solar radiation variations. The results show that (i) paleoclimatic significance of the grain size indices of loess_palaeosol deposit is different with grain size fraction content and sampling points in Chinese Loess Plateau; (ii) the sub_coarse grain fraction is a good proxy index of East Asia winter monsoon strength and therefore can be used to detect the global climate changes; (iii) the content of sub_fine and fine grain fractions is influenced by both the input of sub_coarse grain fraction and pedogenesis; (iv) the sub_coarse fraction exhibits a negative relationship with the sub_fine and fine fraction.鹿化煜 安芷生 1998Science China Earth Sciences1998,41,6:47
2FSHβsubunit gene is associated with major gene controlling litter size in commercial pig breeds显示文摘An insertion fragment in porcine FSHβ subunit gene was cloned by PCR. Sequencing data show that the insertion is a retroposon of 292 bp siting in intronⅠ at the site between +809 and +810 base. Based on these results, a PCR programme was created to genotype animal individuals in different pig breeds at FSHβ locus and polymorphism of FSHβ gene was analyzed. With the combination of genotype and litter size of sows, it was demonstrated that FSHβ locus is closely associated with major gene controlling litter size in commercial pig breeds, such as Yorkshire, Landrace, Durco. Averagely the AA sows give more 1.5 piglets than BB sows do per litter.赵要风 李宁 肖璐 曹更生 陈怡真 张顺 陈永福 吴常信 张建生 孙士铨 徐学清 1998Science China(Life Sciences)1998,41,6:26
3A sedimentological proxy indicator linking changes in loess and deserts in the Quaternary显示文摘From Yulin, which is located in the transitional zone between the Loess Plateau and the Mu Us desert, to Weinan in the southernmost part of the Loess Plateau, 9 loess sections were studied. Grain size analyses show that the advance-retreat changes of the deserts in northern China may be the most important factor controlling changes in the sand particle percentage of the loess-soil sequences during the last glacial-interglacial period. It is thus suggested to use the sand grain content of loess deposits as a proxy indicator of desert variations. Applying this indicator to the last glacial loess deposits in the northwestern part of the Loess Plateau reveals that there were many millennial-scale cycles of the desert environments.丁仲礼 孙继敏 刘东生 1999Science China Earth Sciences1999,42,2:24
4OPTICAL PROPERTIES OF GeO_2 AND Ge NANOCRYSTALS显示文摘he co m pound m aterial of n m size particles Ge O2 Si O2 w as synthesied through hydrolysis of Si( O C2 H4) and Ge Cl4 . A heat treatm ent w as carried out for the sa m ples at 100 ~1200 ℃in air . Its optical property w as deter mined by U V Vis spectur m . We have found that theabsorption edge of spectru m shifted progressively to longer w avelengths . The quantu m size ef fect of nanocrystals appears because crystals gro w and energy of optical band gap reduces d ueto the influence of te m perature . By the analysis of X ray diffraction w e have observed theprocess in w hich the structure of particles changed fro m disorder into order .Y.H.Zhou 1) ,Y.Y.Feng 2) and H.Y.Lu 2) 1)Department of Physics Nanjing Normal University, Nanjing 210097,China 2)Physics and Ch寁O P T I C A L P R O P E R T I E S O F Ge O2 A N D Ge N A N O C R Y S T A L S Y. H. Zhou1) , Y. Y. Feng2) 1999Acta Metallurgica Sinica(English Letters)1999,12,5:22
5Trends in particulate matter and its chemical compositions in China from 2013–2017显示文摘Accurate determination of the atmospheric particulate matter mass concentration and chemical composition is helpful in exploring the causes and sources of atmospheric enthalpy pollution and in evaluating the rationality of environmental air quality control strategies.Based on the sampling and chemical composition data of PM2.5 in different key regions of China in the CARE-China observation network,this research analyzes the environmental air quality data released by the China National Environmental Monitoring Centre during the studied period to determine the changes in the particulate matter mass concentration in key regions and the evolution of the corresponding chemical compositions during the implementation of the Action Plan for Prevention and Control of Air Pollution from 2013-2017.The results show the following.(1)The particulate matter mass concentration in China showed a significant downward trend;however,the PM2.5 annual mass concentration in 64%of cities exceeds the New Chinese Ambient Air Quality Standard(CAAQS)GradeⅡ(GB3095-2012).The region to the east of the Taihang Mountains,the Fenhe and Weihe River Plain and the Urumqi-Changji regions in Xinjiang,all have PM2.5 concentration loading that is still high,and heavy haze pollution occurred frequently in the autumn and winter.(2)During the heavy pollution in the autumn and winter,the concentrations of sulfate and organic components decreased significantly.The mean SO42-concentration in PM2.5 decreased by 76%,12%,81%and 38%in Beijing-Tianjin-Hebei(BTH),the Pearl River Delta(PRD),the Sichuan-Chongqing region(SC)and the Fenhe and Weihe River Plain,respectively.The mean organic matter(OM)concentration decreased by 70%,44%,48%and 31%,respectively,and the mean concentration of NH4+decreased by 68%,1.6%,38%and 25%,respectively.The mean elemental carbon(EC)concentration decreased by 84%and 20%in BTH and SC,respectively,and it increased by 61%and 11%in the PRD and Fenhe and Weihe River Plain,respectively.The mean concentration of mineral and unresolved chemical components(MI)dropped by 70%,24%and 13%in BTH,the PRD and the Fenhe and Weihe River Plain,respectively.The change in the PM2.5 chemical composition is consistent with the decrease of the PM2.5mass concentration.(3)In 2015,the mean OM concentration contributions to fine particles and coarse particles were 13-46%and 46-57%,respectively,and the mean MI concentration contributions to fine particles and coarse and particles were 31-60%and 39-73%,respectively;these values are lower than the 2013 values from the key regions,which is the most important factor behind the decrease of the particulate matter mass concentration.From 2013 to 2015,among the chemical components of different particle size fractions,the peak value of the coarse particle size fraction decreased significantly,and the fine particle size fractions of SO42-,NO3-,and NH4+decreased with the decrease of the particulate matter mass concentration in different particle size fractions.The fine-particle size peaks of SO42-,NO3-and NH4+shifted from 0.65-1.1μm to the finer size range of0.43-0.65μm during the same time frame.Yuesi WANG Wenjie LI Wenkang GAO Zirui LIU Shili TIAN Rongrong SHEN Dongsheng JI Shuai WANG Lili WANG Guiqian TANG Tao SONG Mengtian CHENG Gehui WANG Zhengyu GONG Jiming HAO Yuanhang ZHANG 2019Science China Earth Sciences2019,62,12:23
6全功率变流器可变速抽水蓄能机组的功率调节特性分析显示文摘全功率变流器(full size converter,FSC)可变速抽水蓄能技术是控制电网负荷频率,平衡可再生能源发电波动的有效手段。在介绍三电平FSC可变速抽水蓄能机组整体结构的基础上,给出了机侧变流器和网侧变流器的模型和控制策略。在确定由于电网需求而产生的参考功率的基础上,提出了FSC可变速抽水蓄能机组在发电模式和电动模式时有功功率和无功功率的控制策略。针对所建立的FSC可变速抽水蓄能机组模型,采用冲击响应傅立叶变换法,给出了机组的频谱特性,对照风电波动频谱特性,阐述了全功率机组对可再生能源引起的电网波动控制的有效性。最后对抽水蓄能机组在抑制风电出力波动中的作用进行了仿真验证。畅欣 韩民晓 郑超 2016电力建设2016,37,4:21
7Pretreated methods on loess-palaeosol samples granulometry显示文摘Twenty representative samples were collected from the Chinese loess plateau and each sample was prepared in 6 different ways respectively in order to test the influences of pretreated methods on grain size measurement. The results show that (ⅰ) different pretreated methods can make a big difference for the samples granulometry; (ⅱ) soaking in distilled water for one day, and then treating with an ultrasonic machine for 10 min can make the sample dispersed.Huayu Lu Zhisheng An 1998Chinese Science Bulletin1998,43,3:20
8Construction and Properties of Structure-and Size-controlled Micro/Nano-energetic Materials显示文摘The recent research progress of structure- and size-controlled micro/nano-energetic materials is reviewed, which properties are fundamentally different from those of their corresponding bulk materials. The development of the construction strategies for achieving zero-dimensional (0D), one-dimensional (1D), two-dimensional (2D), and three-dimensional (3D) micro/nanostructures from energetic molecules is introduced. Also, an overview of the unique properties induced by micro/nanostructures and size effects is provided. Special emphasis is focused on the size-dependent properties that are different from those of the conventional micro-sized energetic materials, such as thermal decomposition, sensitivity, combustion and detonation, and compaction behaviors. A conclusion and our view of the future development of micro/nano-energetic materials and devices are given.HUANG Bing CAO Minhua NIE Fude HUANG Hui HU Changwen 2013Defence Technology(防务技术)2013,9,2:20
9Cardioprotection and pharmacological therapies in acute myocardial infarction: Challenges in the current era显示文摘In patients with an acute ST-segment elevation myocardial infarction, timely myocardial reperfusion using primary percutaneous coronary intervention is the most effective therapy for limiting myocardial infarct size, preserving left-ventricular systolic function and reducing the onset of heart failure. Within minutes after the restoration of blood flow, however, reperfusion itself results in additional damage, also known as myocardial ischemia-reperfusion injury. An improved understanding of the pathophysiological mechanisms underlying reperfusion injury has resulted in the identification ofseveral promising pharmacological(cyclosporin-A, exenatide, glucose-insulin-potassium, atrial natriuretic peptide, adenosine, abciximab, erythropoietin, metoprolol and melatonin) therapeutic strategies for reducing the severity of myocardial reperfusion injury. Many of these agents have shown promise in initial proofof-principle clinical studies. In this article, we review the pathophysiology underlying myocardial reperfusion injury and highlight the potential pharmacological interventions which could be used in the future to prevent reperfusion injury and improve clinical outcomes in patients with coronary heart disease.Alberto Dominguez-Rodriguez Pedro Abreu-Gonzalez Russel J Reiter 2014World Journal of Cardiology2014,6,3:18
10Trend analysis of sediment grain size and sedimentary process in the central South Yellow Sea显示文摘With the method of trend analysis of sediment grain size, the sediment transport trend of the fine-grained sediments area in the central South Yellow Sea was studied. The results demonstrated that there is a sedimentation center around the point of 123.4° E, 35.1°N, and the sediments outside the center are transported to it. The patterns of sediment transportation and deposition in the Yellow Sea should be controlled by cyclonic circulation (including the Yellow Sea Cold Water Mass) and cold water gyre. The study also showed that the method of trend analysis of sediment grain size has prospective utilization in the fine-grained sediment deposited area on large-scale continental shelf.SHI Xuefa CHEN Chunfeng LIU Yanguang REN Hong WANG Huiyan 2002Chinese Science Bulletin2002,47,14:17
11Farm size and fertilizer sustainable use: An empirical study in Jiangsu, China显示文摘Inefficient use of fertilizer has caused serious environmental problems and unsustainable development of agriculture in China.To meet the increasing food demand in the future without damaging the ecological environment,Chinese government officially launched the Action Plan for the Zero Growth of Fertilizer Use in 2015.At the same time,China released a series of policies aiming explicitly at expanding farm size and a great number of large scale farmers emerged recently.However,whether the expansion of farm size will be beneficial for the increase of fertilizer use efficiency still remains to be investigated.In this study,we comprehensively explored the relationship between fertilizer use efficiency and farm size.Based on the 4281 farm households’survey data collected by the National Development and Reform Commission(NDRC)of China from 2004 to 2016 in Jiangsu Province,China,this paper applies a stochastic frontier production function to estimate fertilizer use efficiency across farm size and uses a regression model to analyze the influence of farm size on fertilizer use efficiency.The results show that:(1)the average fertilizer use efficiency of whole samples was only 0.60,much lower than the average technical efficiency,indicating that on average half of the fertilizer utilized are excessive in China;and(2)the smallest farm size group get the highest fertilizer use efficiency score.We also provide some possible explanations for the inverse relationship between farm size and fertilizer use efficiency.HU Ling-xiao ZHANG Xiao-heng ZHOU Ying-heng 2019Journal of Integrative Agriculture2019,18,12:17
12地质样品Sr同位素激光原位等离子体质谱(LA-MC-ICP-MS)测定显示文摘Sr同位素在研究岩浆演化及其源区具有重要的示踪作用。MC-ICP-MS的出现为具有高Sr含量地质样品的激光原位Sr同位素测定变成了现实。本文利用Netpune MC-ICP-MS和193nm准分子激光联机,通过滨珊瑚、斜长石、磷灰石和钙钛矿等系列实验,建立了激光原位Sr同位素测定方法。实验结果表明,激光Sr同位素测定中Kr、Rb和稀土元素二价离子的干扰能够有效扣除,而钙聚合物的干扰在Neptune型MC-ICP-MS并不显著。不同激光参数的实验表明,大激光束斑产生更高信号强度,因而Sr同位素精度更高,同一激光束斑大小,激光脉冲频率对Sr同位素精度无明显影响。杨岳衡 吴福元 谢烈文 杨进辉 张艳斌 2009岩石学报2009,25,12:16
13Characteristics of paleoflood deposits archived in unit T0403 of Yuxi Site in the Three Gorges reservoir areas,China显示文摘Based on the detailed analyses,multi-proxies such as AMS 14 C dating,grain size,component and morphology of heavy minerals,micromorphology of zircon,magnetic susceptibility,Rb/Sr and Hg content are used to research the paleoflood sediments archived in the Yuxi Site.The research indicates that, since 7.6 kaBP,at least 16 times of paleoflood with water level above Wusong Elevation 147.024 m(a.s.l.) left deposits in the Neolithic layers of unit T0403 from the Yuxi Site.The results are induced from the following aspects:(1)The plaeoflood sediments take on great similarities with modern flood sediments in the Yuxi Site and Zhongba Site in probability cumulative curves which mainly show a pattern of 3 segments in fluvial pattern.(2)There is some resemblance between the heavy mineral components and the zircon shape characteristics of paleoflood deposits and those of modern flood deposits.(3) Magnetic susceptibility values(40.44―70.10SI)are lower than those of sediments from cultural layers (59.59―188.68SI).(4)Hg values(290.71―742.51 ng/g)are lower than those of sediments from cultural layers(344.16―10518.17 ng/g).(5)Rb/Sr values are higher than those of sediments from cultural layers, while those of the 4th,5th,6th,7th,8th cultural layers are high,which shows that they are inundated by paleoflood.The reason for many flood deposits existing is related to the site situated on the first terrace where the Yuxi River joins with the Yangtze River.As there are some similarities between the plaeoflood sediments and those of the Zhongba Site,it is feasible to confirm the existence of paleoflood sediments based on the above points.ZHU Cheng MA ChunMei XU WeiFeng BAI JiuJiang ZHENG ChaoGui ZHU GuangYao WANG HuiLin CHEN Ye LU XueFeng 2008Chinese Science Bulletin2008,53,S1:16
14Particle size characterization by ultrasonic attenuation spectra显示文摘This paper contributes to extracting information from signals of broadband ultrasonic attenuation spectrum for effective utilization in particle size characterization. The single particle scattering model and the coupled-phase model are formulated simultaneously, the relationship between particle size distribution and ultrasonic spectrum is established, and a convergence criterion for calculation is quantified. Demonstration inversion by the optimum regularization factor method is carried out to yield typical numerical results for discussion. With the experimental set-up developed by the Institute of Particle and Two-Phase Flow Measurement (IPTFM) at the University of Shanghai for Science and Technology, sand sediment particle size is measured by attenuation spectrum and analyzed using the above inversion algorithm and theoretical models. To validate the proposed ultrasonic spectrum particle sizing method, results are compared with those obtained by microscopy.Mingxu Su, Minghua Xue, Xiaoshu Cai, Zhitao Shang, Feng Xu Institute of Particle and Two-Phase Flow Measurement, University of Shanghai for Science and Technology, Shanghai 200093, China 2008Particuology2008,6,4:15
15Size variation of the end Permian conodont Neogondolella at Meishan Section,Changxing,Zhejiang and its significance显示文摘This study is based on both a generic and species level investigation of the individual size of the latest Permian conodont Neogondolella Pa elements collected from Meishan Section A, Changxing, Zhejiang Province. In this study, an obvious size reduction of Neogondolella Pa elements within bed 24e of the upper Changxing Limestone is recognized. The size variation of the Neogon- dolella occurs simultaneously with some important events including the negative shift of δ 13C, change in the ratio of the abundance of cyanobacterial biomarkers versus that of other general bacterial biomarkers and the shallowing of the sea water. Through the investigation of the paleoenvironmental changes and the analysis of the paleoecology of the conodont genus Neogondolella, the authors propose that the major factors for the size reduction of species of the conodont genus Neogondolella are food shortages caused by the mass extinction, the shallowing of the sea water as well as the in- crease in opacity of the sea water during the end Permian. The same phenomenon of Neogondolella size reduction is also observed in preliminary research from the same horizon at Shangsi Section, Sichuan Province. All the evidence suggests that there was a mass extinction that occurred at the horizon of bed 24e, and the evidence supports the viewpoint of a multi-phase mass extinction during the Permian and Triassic transition in South China.LUO Genming LAI Xulong JIANG Haishui ZHANG Kexin 2006Science China Earth Sciences2006,49,4:14
16Seasonal Variations of Observed Raindrop Size Distribution in East China显示文摘Seasonal variations of rainfall microphysics in East China are investigated using data from the observations of a twodimensional video disdrometer and a vertically pointing micro rain radar. The precipitation and rain drop size distribution(DSD) characteristics are revealed for different rain types and seasons. Summer rainfall is dominated by convective rain,while during the other seasons the contribution of stratiform rain to rainfall amount is equal to or even larger than that of convective rain. The mean mass-weighted diameter versus the generalized intercept parameter pairs of convective rain are plotted roughly around the 'maritime' cluster, indicating a maritime nature of convective precipitation throughout the year in East China. The localized rainfall estimators, i.e., rainfall kinetic energy–rain rate, shape–slope, and radar reflectivity–rain rate relations are further derived. DSD variability is believed to be a major source of diversity of the aforementioned derived estimators. These newly derived relations would certainly improve the accuracy of rainfall kinetic energy estimation, DSD retrieval, and quantitative precipitation estimation in this specific region.Long WEN Kun ZHAO Mengyao WANG Guifu ZHANG 2019Advances in Atmospheric Sciences2019,36,4:14
17Management of early gastrointestinal neuroendocrine neoplasms显示文摘Neuroendocrine neoplasms (NENs) of the stomach, duo- denum, appendix or rectum that are small (≤ 1 cm) and well differentiated can be considered 'early' tumors, since they generally have a (very) good prognosis. In the new WHO classification of 2010, these neoplasms are called neuroendocrine tumors/ carcinoids (NETs), grade (G) 1 or 2, and distinguished from poorly differentiated neuroendocrine carcinomas (NECs), G3. NETs are increasing, with a rise in the age-adjusted incidence in the U.S.A. by about 700 % in the last 35 years. Improved early detection seems to be the main reason for these epidemiological changes. Both the better generalavailability of endoscopy, and imaging techniques, have led to a shift in the discovery of smaller-sized (≤ 10-20 mm) intestinal NETs/carcinoids and earlier tumor stages at diagnosis. Endoscopic screening is therefore effective in the early diagnosis, not only of colorectal adenocarcinomas, but also of NETs/carcinoids. Endoscopic removal, followed up with endoscopic surveillance is the treatment of choice in NETs/carcinoids of the stomach, duodenum and rectum that are ≤ 10 mm in size, have a low proliferative activity (G1), do not infiltrate the muscular layer and show no angioinvasion. In all the other intestinal NENs, optimal treatment generally needs surgery and/or medical therapy depending on type, biology and stage of the tumor, as well as the individual situation of the patient.Hans Scherübl Robert T Jensen Guillaume Cadiot Ulrich Stlzel Günter Klppel 2011World Journal of Gastrointestinal Endoscopy2011,3,7:13
18Liver-spleen axis: Intersection between immunity, infections and metabolism显示文摘Spleen has been considered a neglected organ so far, even though is strictly linked to liver. The spleen plays an important role in the modulation of the immune system and in the maintenance of peripheral tolerance via the clearance of circulating apoptotic cells, the differentiation and activation of T and B cells and production of antibodies in the white pulp. Moreover, splenic macrophages are able to remove bacteria from the blood and protect from sepsis during systemic infections. We review the spleen function and its assessment in humans starting from the description of spleen diseases, ranging from the congenital asplenia to secondary hyposplenism. From the literature data it is clear that obesity in humans affects different compartments of immune system, even thought there are still few data available on the implicated mechamisms. The intent is to enable clinicians to evaluate the newly recognized role of metabolic and endocrine functions of the spleen with special emphasis to obesity and nonalcoholic fatty liver disease in the context of the available literature.Moreover, understanding the spleen function could be important to develop appropriate prevention strategies in order to counteract the pandemia of obesity. In this direction, we suggest spleen longitudinal diameter at ultrasonography, as simple, cheap and largely available tool, be used as new marker for assessing splenic function, in the context of the so-called liver-spleen axis.Giovanni Tarantino Antonella Scalera Carmine Finelli 2013World Journal of Gastroenterology2013,19,23:13
19Grain size-dependent Mg/Si ratio effect on the microstructure and mechanical/electrical properties of Al-Mg-Si-Sc alloys显示文摘Al-Mg-Si-Sc alloys with different Mg/Si ratio(<1.73 in wt.% vs>1.73 in wt.%) and different grain size(coarse grains vs ultrafine grains) were prepared, which allowed to investigate the grain size-dependent Mg/Si ratio effect on the microstructural evolution and concomitantly on the hardness and electrical conductivity when subjected to aging at 200℃. In the coarse-grained Al-Mg-Sc-Sc alloys, the β' precipitation within the grain interior and also the precipitation hardening were highly dependent on the Mg/Si ratio,while the electrical conductivity was slightly affected by the Mg/Si ratio. A promoted β' precipitation was found in the case of Si excess(Mg/Si ratio <1.73), much greater than in the case of Mg excess(Mg/Si ratio>1.73). While in the ultrafine-grained Al-Mg-Si-Sc alloys, the electrical conductivity rather than the hardness was more sensitive to the Mg/Si ratio. The alloy with Si excess displayed electrical conductivity much higher than its counterpart with Mg excess. This is rationalized by the grain boundary precipitation promoted by Si, which reduced the solute atoms and precipitates within the grain interior. Age softening was found in the ultrafine-grained alloy with Si excess, but the ultrafine-grained alloy with Mg excess held the hardness almost unchanged during the aging. The hardness-conductivity correlation is comprehensively discussed by considering the coupling effect of Mg/Si ratio and grain size. A strategy to simultaneously increase the hardness/strength and electrical conductivity is proposed for the Al-Mg-SiSc alloys, based on present understanding of the predominant factors on strengthening and conductivity,respectively.Shengyu Jiang Ruihong Wang 2019Journal of Materials Science & Technology2019,35,7:13
20油溶性纳米铜的制备及其在SF15W/40汽油机油中的摩擦学性能(英文)显示文摘采用液相化学还原法结合界面生长法,以醋酸铜为母体,维生素C(Vc)为还原剂,聚乙二醇2000为修饰剂,正丁醇为生长剂,制得粒度分布为18.2~80.2nm、平均粒度为44.7nm的油溶性球形纳米Cu样品。XRD分析表明样品的晶格常数膨胀率为1.478%。将样品添加到SF15W/40汽油机油中制得金属纳米润滑油。高浓度激光粒度仪检测表明,该金属纳米润滑油具有优异的分散稳定性。在UMT-Ⅱ摩擦磨损试验机上考察SF15W/40汽油机油、金属纳米润滑油的摩擦磨损性能。结果表明:与SF15W/40汽油机油相比,金属纳米润滑油较大程度降低了摩擦系数,减小了磨损量,显著改善了SF15W/40汽油机油的摩擦性能;纳米Cu的最佳添加量为0.8%。潘秋红 张锡凤 2010稀有金属材料与工程2010,39,10:12
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