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   3447910篇
  免费   296087篇
  国内免费   13878篇
耳鼻咽喉   47315篇
儿科学   108890篇
妇产科学   87662篇
基础医学   549321篇
口腔科学   93061篇
临床医学   312232篇
内科学   611316篇
皮肤病学   89294篇
神经病学   297228篇
特种医学   137982篇
外国民族医学   299篇
外科学   533654篇
综合类   105988篇
现状与发展   24篇
一般理论   2264篇
预防医学   293381篇
眼科学   78669篇
药学   237395篇
  24篇
中国医学   9547篇
肿瘤学   162329篇
  2021年   55075篇
  2020年   35051篇
  2019年   58053篇
  2018年   71274篇
  2017年   54242篇
  2016年   59927篇
  2015年   74062篇
  2014年   108356篇
  2013年   173371篇
  2012年   91985篇
  2011年   91848篇
  2010年   116470篇
  2009年   120959篇
  2008年   78973篇
  2007年   82136篇
  2006年   92757篇
  2005年   88305篇
  2004年   90305篇
  2003年   81238篇
  2002年   70357篇
  2001年   110999篇
  2000年   104589篇
  1999年   102170篇
  1998年   66155篇
  1997年   63777篇
  1996年   61980篇
  1995年   57732篇
  1994年   51750篇
  1993年   48349篇
  1992年   73474篇
  1991年   70201篇
  1990年   66526篇
  1989年   65086篇
  1988年   60363篇
  1987年   59035篇
  1986年   55852篇
  1985年   55957篇
  1984年   50407篇
  1983年   45746篇
  1982年   42540篇
  1981年   39963篇
  1980年   37667篇
  1979年   41756篇
  1978年   36555篇
  1977年   33112篇
  1976年   30450篇
  1975年   29026篇
  1974年   30265篇
  1973年   29027篇
  1972年   27028篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
941.
What is the value of bcl-2 protein detection for histopathologists?   总被引:15,自引:0,他引:15  
  相似文献   
942.
Anti-HPA-1a platelet antibody levels in pregnant women with a history of fetomaternal alloimmune thrombocytopenia (FMAIT) were monitored longitudinally using the monoclonal antibody immobilisation of platelet antigens (MAIPA) assay, in order to examine any variation in optical density (OD) readings obtained over the course of pregnancy and after delivery. Seven women were selected; 4 were studied retrospectively and 3 prospectively (the latter being treated with intravenous gammaglobulin; IVGG). Levels of anti-HPA-1a were measured at various intervals after delivery of the first affected infant, to post delivery of the following affected infant. A decrease in MAIPA OD was demonstrated in all patients during the course of these pregnancies. This assay is a useful tool for monitoring anti-HPA-1a in women with a history of infants affected with FMAIT. A maternal antibody 'resting' level prior to, or early in the first trimester, must be established for comparison.  相似文献   
943.
944.
945.
946.
为提供微波辐射安全标准必要的数据,研究了不同极化方向微波辐射能量对猕猴的影响。实验在医学微波无反射室中进行,分为电场,磁场和微波传输方向极化组,辐射频率1GHz,用红外热图技术,对暴露在三种极化方向电磁场中猕猴面部各解剖特片部位及胸部在辐射前后进行温度变化的定量分析。  相似文献   
947.
The aim of this work was to compare the subcellular distribution of the oestrogen receptor from the uteri of rats treated with vehicle alone (control group), oestradiol or one of the antio-estrogenic drugs tamoxifen and ZD 182,780. The nuclear, microsomal and cytosolic oestrogen receptor contents were evaluated by an immunoenzymatic method (“ER-EIA” kit from Abbott Laboratories) and the results in each fraction were expressed as a percentage of the total number of receptors. Parallel studies were performed to assess the uterotrophic effect of these drugs and to assess that they had reached the uterus. In the control group, we found that the oestrogen receptor was distributed mainly between the microsomal (29.1 ± 1.3%) and cytosolic (68.1 ±0.9%) fractions, with only a small amount located in the nucleus (2.8 ± 0.5%). When oestradiol was administered, the oestrogen receptor distribution was: nuclear 11.7 ± 2.0, microsomal 15.5 ± 1.3 and cytosolic 72.8 ± 3.3% and, in the tamoxifen group, the results were: nuclear 18.5 ± 1.5, microsomal 26.0 ± 31 and cytosolic 55.5 ± 3.4%, which shows a relative shift both to the control and the oestradiol-treated groups. In the uteri of rats treated with ZD 182,780 the results were very similar to those obtained in the control group. Our results indicate that the subcellular distribution of the oestrogen receptor varies according to the drug administered and that this receptor may not be located in a single subcellular compartment. Moreover, the nuclear uptake of the ZD 182,780-oestrogen receptor complex seems to be blocked, possibly due to impaired receptor dimerization. In the case of tamoxifen, the intracellular transport of the receptor also seems to be blocked, probably due to the nuclear retention of the receptor, thus suggesting that tamoxifen must impair the oestrogen receptor function on a step subsequent to the receptor dimerization.  相似文献   
948.
Summary Contradictory immunohistochemical data have been reported on the localization of N-acetylaspartylglutamate in the rat forebrain, using different carbodiimide fixation protocols and antibody purification methods. In one case, N-acetylaspartylglutamate immunoreactivity was observed in apparent interneurons throughout all allocortical and isocortical regions, suggesting possible colocalization with GABA. In another case, strong immunoreactivity was observed in numerous pyramidal cells in neocortex and hippocampus, suggesting colocalization with glutamate or aspartate. Reconciling these disparate findings is crucial to understanding the role of N-acetylaspartylglutamate in nervous system function. Antibodies to N-acetylaspartylglutamate and a structurally related molecule, N-acetylaspartate, were purified in stages, and their cross-reactivities with protein conjugates of N-acetylaspartylglutamate and N-acetylaspartate were monitored at each stage by solidphase immunoassay. Reduction of the cross-reactivity of the anti-N-acetylaspartylglutamate antibodies to N-acetylaspartateprotein conjugates to about 1% eliminated significant staining of most pyramidal neurons in the rat forebrain. Utilizing highly purified antibodies, the distributions of N-acetylaspartylglutamate and N-acetylaspartate were examined in several major telencephalic and diencephalic regions of the rat, and were found to be distinct. N-acetylaspartylglutamate-immunoreactivity was observed in specific neuronal populations, including many groups thought to use GABA as a neurotransmitter. Among these were the globus pallidus, ventral pallidum, entopeducular nucleus, thalamic reticular nucleus, and scattered non-pyramidal neurons in all layers of isocortex and allocortex. N-acetylaspartate-immunoreactivity was more broadly distributed than N-acetylaspartylglutamate-immunoreactivity in the rat forebrain, appearing strongest in many pyramidal neurons. Although N-acetylaspartate-immunoreactivity was found in most neurons, it exhibited a great range of intensities between different neuronal types.  相似文献   
949.
950.
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