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   51768篇
  免费   3327篇
  国内免费   315篇
耳鼻咽喉   411篇
儿科学   1244篇
妇产科学   1248篇
基础医学   7520篇
口腔科学   963篇
临床医学   4329篇
内科学   12228篇
皮肤病学   929篇
神经病学   4563篇
特种医学   1819篇
外国民族医学   11篇
外科学   7386篇
综合类   287篇
一般理论   17篇
预防医学   3867篇
眼科学   819篇
药学   3339篇
中国医学   191篇
肿瘤学   4239篇
  2023年   283篇
  2022年   628篇
  2021年   1330篇
  2020年   794篇
  2019年   1199篇
  2018年   1520篇
  2017年   975篇
  2016年   1201篇
  2015年   1448篇
  2014年   1919篇
  2013年   2471篇
  2012年   3759篇
  2011年   3802篇
  2010年   2175篇
  2009年   2067篇
  2008年   3246篇
  2007年   3318篇
  2006年   3167篇
  2005年   3041篇
  2004年   2821篇
  2003年   2707篇
  2002年   2577篇
  2001年   905篇
  2000年   778篇
  1999年   791篇
  1998年   548篇
  1997年   460篇
  1996年   412篇
  1995年   354篇
  1994年   274篇
  1993年   306篇
  1992年   445篇
  1991年   370篇
  1990年   356篇
  1989年   341篇
  1988年   284篇
  1987年   224篇
  1986年   254篇
  1985年   214篇
  1984年   179篇
  1983年   156篇
  1982年   109篇
  1981年   122篇
  1980年   87篇
  1979年   102篇
  1976年   59篇
  1975年   70篇
  1974年   70篇
  1973年   57篇
  1969年   58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.
6.
7.
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   
8.
9.
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   
10.

Introduction

Invasive meningococcal disease (IMD) is a severe disease mainly affecting infants and young children. The most common serogroup causing IMD in Germany is the serogroup type B Neisseria meningitidis (MenB). The aim of the present study is to estimate the economic burden of MenB-related IMD in Germany.

Method

A bottom-up, model-based costing approach has been used to calculate the diagnose- and age-specific yearly lifetime costs of a hypothetical cohort of MenB-related IMD cases. Direct costs contain the treatment cost for the acute phase of the disease, long-term sequelae, costs for rehabilitation, and public health response. Indirect costs are calculated for the human-capital approach and the friction-cost approach considering productivity losses of patients or parents for the acute phase and long-term sequelae. Publicly available databases from the Federal Statistical Office, the SOEP panel data set, literature, and expert opinion were used as data sources. All future costs beyond the reference year of 2015 were discounted at 3%.

Results

The total costs for the hypothetical cohort (343 patients) from a societal perspective are €19.6 million (€57,100/IMD case) using the friction-cost approach and €58.8 million (€171,000/IMD case) using the human-capital approach. Direct costs amount to €18.6 million or €54,300 €/case. Sequelae are responsible for 81% of the direct costs/case.

Discussion

The elevated costs/MenB-related IMD case reflect the severity of the disease. The total costs are sensitive to the productivity-loss estimation approach applied. MenB is an uncommon but severe disease; The costs/case reflect the severity of the disease and is within the same magnitude as for human papilloma virus infections. The available literature on sequelae is due to the uncommonness limited and heterogeneous.  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