首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   2393篇
  免费   302篇
  国内免费   2篇
  2021年   22篇
  2020年   13篇
  2019年   21篇
  2018年   20篇
  2017年   19篇
  2016年   49篇
  2015年   84篇
  2014年   91篇
  2013年   100篇
  2012年   135篇
  2011年   148篇
  2010年   81篇
  2009年   78篇
  2008年   98篇
  2007年   102篇
  2006年   113篇
  2005年   114篇
  2004年   78篇
  2003年   90篇
  2002年   104篇
  2001年   67篇
  2000年   67篇
  1999年   64篇
  1998年   41篇
  1997年   24篇
  1996年   21篇
  1995年   31篇
  1994年   32篇
  1993年   21篇
  1992年   53篇
  1991年   39篇
  1990年   52篇
  1989年   40篇
  1988年   48篇
  1987年   34篇
  1986年   49篇
  1985年   36篇
  1984年   37篇
  1983年   25篇
  1982年   21篇
  1981年   17篇
  1980年   23篇
  1979年   20篇
  1978年   24篇
  1977年   13篇
  1976年   19篇
  1975年   15篇
  1974年   21篇
  1969年   19篇
  1968年   13篇
排序方式: 共有2697条查询结果,搜索用时 15 毫秒
1.
2.
3.
Animal studies are very useful in detection of early disease indicators and in unravelling the pathophysiological processes underlying core psychiatric disorder phenotypes. Early indicators are critical for preventive and efficient treatment of progressive psychiatric disorders like anorexia nervosa. Comparable to physical hyperactivity observed in anorexia nervosa patients, in the activity-based anorexia rodent model, mice and rats express paradoxical high voluntary wheel running activity levels when food restricted. Eleven inbred mouse strains and outbred Wistar WU rats were exposed to the activity-based anorexia model in search of identifying susceptibility predictors. Body weight, food intake and wheel running activity levels of each individual mouse and rat were measured. Mouse strains and rats with high wheel running activity levels during food restriction exhibited accelerated body weight loss. Linear mixed models for repeated measures analysis showed that baseline wheel running activity levels preceding the scheduled food restriction phase strongly predicted activity-based anorexia susceptibility (mice: Beta  =  −0.0158 (±0.003 SE), P<0.0001; rats: Beta  =  −0.0242 (±0.004 SE), P<0.0001) compared to other baseline parameters. These results suggest that physical activity levels play an important role in activity-based anorexia susceptibility in different rodent species with genetically diverse background. These findings support previous retrospective studies on physical activity levels in anorexia nervosa patients and indicate that pre-morbid physical activity levels could reflect an early indicator for disease severity.  相似文献   
4.
UDPgalactose:sn-glycerol-3-phosphate α-D-galactosyltransferase (IFP-synthase, EC 2.4.1.96) shows low activity in extracts prepared from standard volume cells of Poterioochromonals malhamensis under certain conditions. This inactive enzyme has been partially purified by chromatography on DEAE-cellulose, Sephadex G-150 and α-lactalbumin-agarose. It can be activated by an auxiliary enzyme which can be eluted from membranes and which has been purified to homogeneity by chromatography on DEAE-Sephacel and immobilized hemoglobin and fetuin. The activating enzyme is inhibited by chymostatin, antipain and diisopropylfluorophosphate and does not require divalent ions. It consists of a single peptide chain of molecular weight 46 000, can split certain proteins and appears to be a serine proteinase operating around a pH of 6.0. The activating proteinase is irreversibly generated in the crude homogenates on addition of Ca2+ and also shows increased activity shortly after cell shrinkage. This might indicate that it represents one of the possibilities to render the galactosyltransferase active as a result of the physiological stimulus.  相似文献   
5.
6.
We have investigated the binding of porcine pancreatic phospholipase A2 (PA2) to n-hexadecylphosphocholine (C16PN) micelles using optical detection of triplet state magnetic resonance (ODMR) spectroscopy. The zero field splittings (zfs) of the single Trp3 residue undergo significant changes upon binding of PA2 to C16PN micelles. Zfs titrations of PA2 vs C16PN indicate that the binding stoichiometry is C16PN:PA2 approximately 25. A reduction of the (E) parameter from 1.227 to 1.135 GHz is postulated to result from Stark effects caused by the binding of a polar group (possibly phosphocholine) near Trp3 in the PA2-C16PN micelle complex.  相似文献   
7.
8.
Consistency of production is recognised as an important aspect of vaccine manufacture and suitably validated in vitro assays are required for quality control testing of these products. For the manufacture and batch release of tetanus vaccines, antigen content and integrity, and degree of adsorption of antigen to the adjuvant are critical parameters that should be monitored for consistency. Here we describe the development and use of an Enzyme Linked Immunosorbent Assay (ELISA) to quantify tetanus antigen in combined vaccine products and to measure the degree of adsorption of antigen to adjuvant. Whilst the antigen assay cannot be assumed to predict potency for different products, it can be used as part of a panel of in vitro methods to provide a more informative product profile and to monitor trends in production. The antigen assay is particularly valuable for providing quantitative information on every final lot when modifications of in vivo potency tests, such as single dilution assays, are used.  相似文献   
9.
Sesame Utilization in China: New Archaeobotanical Evidence from Xinjiang. A cache of sesame (Sesamum indicum L.) seeds, discovered in the Thousand Buddha Grottoes at Boziklik, Turpan, China, dating to ca. 700 years before present (BP), is hard evidence of their use in China since that time. Morphological and anatomical features suggest a white sesame cultivar. The sizeable quantity unearthed implies that sesame was a valued commodity that could provision the monks and enrich the diet of ancient inhabitants as an oil source.  相似文献   
10.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号