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   25366篇
  免费   1678篇
  国内免费   186篇
耳鼻咽喉   247篇
儿科学   569篇
妇产科学   483篇
基础医学   3755篇
口腔科学   302篇
临床医学   2436篇
内科学   6393篇
皮肤病学   367篇
神经病学   2151篇
特种医学   1102篇
外国民族医学   8篇
外科学   4465篇
综合类   97篇
一般理论   4篇
预防医学   1362篇
眼科学   237篇
药学   1365篇
中国医学   42篇
肿瘤学   1845篇
  2023年   127篇
  2022年   154篇
  2021年   626篇
  2020年   369篇
  2019年   605篇
  2018年   716篇
  2017年   473篇
  2016年   575篇
  2015年   729篇
  2014年   957篇
  2013年   1242篇
  2012年   1972篇
  2011年   1962篇
  2010年   1124篇
  2009年   1137篇
  2008年   1754篇
  2007年   1738篇
  2006年   1700篇
  2005年   1744篇
  2004年   1600篇
  2003年   1511篇
  2002年   1420篇
  2001年   224篇
  2000年   173篇
  1999年   241篇
  1998年   270篇
  1997年   239篇
  1996年   203篇
  1995年   167篇
  1994年   123篇
  1993年   150篇
  1992年   127篇
  1991年   98篇
  1990年   107篇
  1989年   74篇
  1988年   71篇
  1987年   61篇
  1986年   64篇
  1985年   59篇
  1984年   46篇
  1983年   62篇
  1982年   47篇
  1981年   51篇
  1980年   44篇
  1979年   34篇
  1978年   24篇
  1976年   21篇
  1975年   27篇
  1973年   21篇
  1968年   20篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
1.
2.
Animal and human studies suggest fish oil and green tea may have protective effect on prostate cancer. Fatty acid synthase (FAS) has been hypothesized to be linked to chemoprotective effects of both compounds. This study evaluated the independent and joint effects of fish oil (FO) and green tea supplement (epigallocatechin-3-gallate, EGCG) on FAS and Ki-67 levels in prostate tissue. Through a double-blinded, randomized controlled trial with 2 × 2 factorial design, 89 men scheduled for repeat prostate biopsy following an initial negative prostate biopsy were randomized into either FO alone (1.9 g DHA + EPA/day), EGCG alone (600 mg/day), a combination of FO and EGCG, or placebo. We used linear mixed-effects models to test the differences of prostate tissue FAS and Ki-67 by immunohistochemistry between pre- and post-intervention within each group, as well as between treatment groups. Results did not show significant difference among treatment groups in pre-to-post-intervention changes of FAS (P = 0.69) or Ki-67 (P = 0.26). Comparing placebo group with any of the treatment groups, we did not find significant difference in FAS or Ki-67 changes (all P > 0.05). Results indicate FO or EGCG supplementation for a short duration may not be sufficient to produce biologically meaningful changes in FAS or Ki-67 levels in prostate tissue.  相似文献   
3.
4.
5.
Melatonin receptors play important roles in the regulation of circadian and seasonal rhythms, sleep, retinal functions, the immune system, depression, and type 2 diabetes development. Melatonin receptors are approved drug targets for insomnia, non‐24‐hour sleep‐wake disorders, and major depressive disorders. In mammals, two melatonin receptors (MTRs) exist, MT1 and MT2, belonging to the G protein‐coupled receptor (GPCR) superfamily. Similar to most other GPCRs, reliable antibodies recognizing melatonin receptors proved to be difficult to obtain. Here, we describe the development of the first monoclonal antibodies (mABs) for mouse MT1 and MT2. Purified antibodies were extensively characterized for specific reactivity with mouse, rat, and human MT1 and MT2 by Western blot, immunoprecipitation, immunofluorescence, and proximity ligation assay. Several mABs were specific for either mouse MT1 or MT2. None of the mABs cross‐reacted with rat MTRs, and some were able to react with human MTRs. The specificity of the selected mABs was validated by immunofluorescence microscopy in three established locations (retina, suprachiasmatic nuclei, pituitary gland) for MTR expression in mice using MTR‐KO mice as control. MT2 expression was not detected in mouse insulinoma MIN6 cells or pancreatic beta‐cells. Collectively, we report the first monoclonal antibodies recognizing recombinant and native mouse melatonin receptors that will be valuable tools for future studies.  相似文献   
6.
7.
Magnetic resonance elastography aims to non-invasively and remotely characterize the mechanical properties of living tissues. To quantitatively and regionally map the shear viscoelastic moduli in vivo, the technique must achieve proper mechanical excitation throughout the targeted tissues. Although it is straightforward, ante manibus, in close organs such as the liver or the breast, which practitioners clinically palpate already, it is somewhat fortunately highly challenging to trick the natural protective barriers of remote organs such as the brain. So far, mechanical waves have been induced in the latter by shaking the surrounding cranial bones. Here, the skull was circumvented by guiding pressure waves inside the subject's buccal cavity so mechanical waves could propagate from within through the brainstem up to the brain. Repeatable, reproducible and robust displacement fields were recorded in phantoms and in vivo by magnetic resonance elastography with guided pressure waves such that quantitative mechanical outcomes were extracted in the human brain.  相似文献   
8.
9.
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