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   45024篇
  免费   4671篇
  国内免费   1220篇
耳鼻咽喉   224篇
儿科学   1062篇
妇产科学   348篇
基础医学   15445篇
口腔科学   547篇
临床医学   3161篇
内科学   7511篇
皮肤病学   1290篇
神经病学   1609篇
特种医学   2474篇
外国民族医学   9篇
外科学   2920篇
综合类   4910篇
现状与发展   14篇
预防医学   1835篇
眼科学   327篇
药学   2686篇
  8篇
中国医学   1222篇
肿瘤学   3313篇
  2024年   92篇
  2023年   660篇
  2022年   1124篇
  2021年   1658篇
  2020年   1458篇
  2019年   1735篇
  2018年   1850篇
  2017年   1664篇
  2016年   1593篇
  2015年   1775篇
  2014年   2556篇
  2013年   3046篇
  2012年   2315篇
  2011年   2649篇
  2010年   2117篇
  2009年   1969篇
  2008年   2045篇
  2007年   1961篇
  2006年   1785篇
  2005年   1553篇
  2004年   1551篇
  2003年   1369篇
  2002年   1109篇
  2001年   1033篇
  2000年   880篇
  1999年   803篇
  1998年   850篇
  1997年   779篇
  1996年   720篇
  1995年   718篇
  1994年   708篇
  1993年   631篇
  1992年   387篇
  1991年   303篇
  1990年   341篇
  1989年   276篇
  1988年   204篇
  1987年   156篇
  1986年   150篇
  1985年   328篇
  1984年   367篇
  1983年   232篇
  1982年   292篇
  1981年   232篇
  1980年   184篇
  1979年   174篇
  1978年   120篇
  1977年   102篇
  1976年   131篇
  1975年   74篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
TSG-6基因在3T3-L1脂肪细胞诱导分化中表达水平的变化   总被引:2,自引:0,他引:2  
[目的] 探讨TSG-6基因在3T3-L1脂肪细胞诱导分化中表达水平的变化。[方法] 采用细胞培养和RT-PCR技术,检测细胞诱导分化不同时段脂肪细胞中TSG-6基因的表达水平。[结果] ①随着脂肪细胞逐渐分化成熟,TSG-6基因mRNA表达水平逐渐升高;②TSG-6基因表达水平除在细胞分化第0-2d、第3-5d和第7-10d各时段内差异无显著性(P>0.05)外,其余各时段之间表达水平差异均有显著性(P<0.05)。[结论] TSG-6基因与细胞分化以及脂原形成可能相关。  相似文献   
52.
肌钙蛋白T在诊断急性心肌梗死中的应用   总被引:2,自引:0,他引:2  
采用肌钙蛋白T半定量试纸条检测急性心肌梗死16例,心绞痛13例,以20例健康体检者为对照组。结果显示,AMI组阳性反应15例,心绞组仅1例阳性,对照组均为阴性,结果提示,TnT半定量试纸条检测法在AMI诊断中,敏感性和特异性较高,方法简便方便,尤其适用于急诊室,内科监护病房及基层医院使用。  相似文献   
53.
Flow-independent angiography (FIA), an approach that isolates arterial blood using MR relaxation characteristics rather than flow effects, was evaluated for application in peripheral vascular disease (PVD). First, pilot studies were conducted in which FIA coronal projection images were obtained from controls and symptomatic patients with PVD to assess clinical utility. All control images corresponded to the expected leg arterial anatomy with little interference from deep veins (one of five) and muscle (zero of five). Superficial venous signal was less well suppressed in comparison to deep veins (four of five). Images of symptomatic patients were less consistent with difficulty suppressing muscle and deep venous signal in some cases and edema when present. We then compared T2 values for muscle (T2m, tibialis anterior), arterial blood (femoral and popliteal arteries), and venous blood (femoral, popliteal, and saphenous veins) in controls (n = 8) and symptomatic patients with intermittent claudication (n = 5) or ischemic rest pain (n = 7). Changes in T2 measurements of various tissues accounted for poorer contrast in symptomatic patients. Patients with ischemic rest pain had significantly higher T2m compared with controls (T2m = 39.3 ± 2.1 (1 standard error of the mean [SEM]) versus 30.9 ± .4, P < .01). For all measurements, other than saphenous vein, variances were greater in symptomatic patients. To realize the inherent advantages of FIA for this clinical application, additional work on suppression of signals from muscle, veins, and edema is required. One promising approach involves shifting from projection images to three-dimensional acquisitions for improved tissue suppression.  相似文献   
54.
本文应用磁性磷酸酶-抗碱性磷酸酶桥联酶标技术(APAAP),对27例原发性肾小球疾病患者外周血T淋巴细胞亚群进行观察。结果表明:本组病例表现为CD细胞升高,CD细胞减少,和CD/CD比值增加。提示原发性肾小球疾病可导致细胞免疫功能改变,T淋巴细胞亚群的变化,是肾组织损害的一个间接证据,可作为临床诊断一个有价值的参考指标。  相似文献   
55.
We investigated populations of the infiltrating cells in Bowen's disease (BD) and squamous cell carcinoma (SCC), both of which arose in the same patient, using the Avidin-Biotin-peroxidase complex method with eight monoclonal antibodies. T lymphocytes were most predominant among infiltrating cells; NK cells, B cells, and monocytes were rarely seen in either BD or SCC. Analysis of subsets of the infiltrating T lymphocytes revealed that the number of suppressor/cytotoxic (s/c) T cells was twice that of helper/inducer (h/i) T cells in BD, while the number of s/c T cells was lower than that of h/i T cells in SCC. The immunohistochemical results in the present case differed from those of predominant infiltration of h/i T cells and of s/c T cells in three other reports of BD and SCC. These results suggest that the population of the cellular infiltrates may be modulated by the nature of tumors and by the immuno-competent state of the hosts.  相似文献   
56.
57.
58.
59.
精神分裂症服用氯氮平能降低其甲状腺素水平的对照分析   总被引:2,自引:0,他引:2  
目的探索氯氮平治疗是否影响T3、T4和TSH水平.方法对17例精神分裂症患者,给予氯氮平治疗第4天和第4周末分别测定T3、T4和TSH水平.结果治疗第4周末的T3(3.309±0.689)、T4(9.449±1.941)水平比第4天的T3(3.915±0.850)、T4(11.178±2.180)水平明显降低(P均<0.05).结论氯氮平治疗能降低甲状腺素水平.  相似文献   
60.
Syphilis is a chronic disease characterized by hematogenous dissemination of Treponema pallidum into tissues such as the cardiovascular and central nervous systems. In order to test whether these aspects of the pathogenesis of syphilis reflect an ability of T. pallidum to invade vascular entothelial surfaces, we explored the association of T. pallidum with human and rabbit endothelial cells in vitro. Using radiolabeled motile organisms, we found that treponemal attachment was two times greater to rabbit aortic endothelial cells and human umbilical endothelial cells than to HeLa cells. Mild trypsinization of attached treponemes resulted in release from cells of all organisms detectable by darkfield microscopy without visible damage to the monolayer. Nevertheless, 25% of the counts representing T. pallidum remained associated with the cell monolayers. Further trypsin treatment to release the monolayer and differential centrifugation showed that 80% of the remaining cell-associated counts were not within the cells. These results suggest that some treponemes had associated with the monolayer in a trypsin resistant niche. Additionally, motile T. pallidum passed through tight functioned endothelial cell monolayers on membrane filters under conditions were heat-killed T. pallidum and the host indigenous nonpathogen. T. phagedenis biotype Reiter failed to do so. Electron micrographs of transverse sections through the monolayers showed many T. pallidum in junctions between endothelial cells. These studies suggest that T. pallidum may leave the circulation by passing between endothelial cells.  相似文献   
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