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   193181篇
  免费   13493篇
  国内免费   4542篇
耳鼻咽喉   1366篇
儿科学   2684篇
妇产科学   3072篇
基础医学   23951篇
口腔科学   3379篇
临床医学   14169篇
内科学   25803篇
皮肤病学   2234篇
神经病学   12127篇
特种医学   6658篇
外国民族医学   2篇
外科学   20466篇
综合类   26247篇
现状与发展   21篇
一般理论   8篇
预防医学   15155篇
眼科学   2291篇
药学   25827篇
  55篇
中国医学   12631篇
肿瘤学   13070篇
  2024年   331篇
  2023年   2365篇
  2022年   4906篇
  2021年   7969篇
  2020年   6417篇
  2019年   6448篇
  2018年   6558篇
  2017年   7022篇
  2016年   7021篇
  2015年   6706篇
  2014年   7936篇
  2013年   11813篇
  2012年   9518篇
  2011年   11573篇
  2010年   7368篇
  2009年   7670篇
  2008年   9094篇
  2007年   10120篇
  2006年   9571篇
  2005年   8861篇
  2004年   7581篇
  2003年   6762篇
  2002年   5319篇
  2001年   4821篇
  2000年   4025篇
  1999年   3445篇
  1998年   2709篇
  1997年   2829篇
  1996年   2537篇
  1995年   2208篇
  1994年   2105篇
  1993年   1777篇
  1992年   1647篇
  1991年   1538篇
  1990年   1323篇
  1989年   1082篇
  1988年   1031篇
  1987年   945篇
  1986年   870篇
  1985年   1257篇
  1984年   1010篇
  1983年   747篇
  1982年   791篇
  1981年   638篇
  1980年   628篇
  1979年   496篇
  1978年   314篇
  1977年   272篇
  1976年   256篇
  1975年   209篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
《Vaccine》2022,40(16):2370-2378
Porcine reproductive and respiratory syndrome virus (PRRSV) and Mycoplasma hyopneumoniae (M. hyopneumoniae, Mhp) are two of the most common pathogens involved in the porcine respiratory disease complex (PRDC) resulting in significant economic losses worldwide. Vaccination is the most effective approach to disease prevention. Since PRRSV and Mhp co-infections are very common, an efficient dual vaccine against these pathogens is required for the global swine industry. Compared with traditional vaccines, multi-epitope vaccines have several advantages, they are comparatively easy to produce and construct, are chemically stable, and do not have an infectious potential. In this study, to develop a safe and effective vaccine, B cell and T cell epitopes of PRRSV-GP5, PRRSV-M, Mhp-P46, and Mhp-P65 protein had been screened to construct a recombinant epitope protein rEP-PM that has good hydrophilicity, strong antigenicity, and high surface accessibility, and each epitope is independent and complete. After immunization in mice, rEP-PM could induce the production of high levels of antibodies, and it had good immunoreactivity with anti-rEP-PM, anti-PRRSV, and anti-Mhp antibodies. The anti-rEP-PM antibody specifically recognizes proteins from PRRSV and Mhp. Moreover, rEP-PM induced a Th1-dominant cellular immune response in mice. Our results showed that the rEP-PM protein could be a potential candidate for the development of a safe and effective multi-epitope peptide combined vaccine to control PRRSV and Mhp infections.  相似文献   
12.
13.
14.
15.
MicroRNAs (miRNAs) play important roles in prostate cancer development. However, it remains unclear how individual miRNAs contribute to the initiation and progression of prostate cancer. Here we show that a basal layer‐enriched miRNA is required for prostate tumorigenesis. We identify miR‐205 as the most highly expressed miRNA and enriched in the basal cells of the prostate. Although miR‐205 is not required for normal prostate development and homeostasis, genetic deletion of miR‐205 in a Pten null tumor model significantly compromises tumor progression and does not promote metastasis. In Pten null basal cells, loss of miR‐205 attenuates pAkt levels and promotes cellular senescence. Furthermore, although overexpression of miR‐205 in prostate cancer cells with luminal phenotypes inhibits cell growth in both human and mouse, miR‐205 has a minimal effect on the growth of a normal human prostate cell line. Taken together, we have provided genetic evidence for a requirement of miR‐205 in the progression of Pten null‐induced prostate cancer.  相似文献   
16.
This study is focussed on micro-encapsulation of essential oils in polylactic acid (PLA) and a poly(methyl methacrylate) (PMMA) matrix as well as blends of the same. Microspheres were prepared by the solvent evaporation technique and characterised by scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and Fourier transform infra-red spectroscopy (FTIR). The encapsulation efficiencies and release profiles of the essential oils were studied by gas chromatography mass spectrometry (GC-MS) and head-space solid-phase microextraction GC-MS, respectively. Furthermore, the microspheres were tested for antibacterial activity against both Gram-negative and Gram-positive bacterial strains.

The results showed that the microspheres compositions (PLA/PMMA ratio) have significant effect on their characteristics. The process adopted for preparing the microspheres promoted formation of spherical particles at the sizes of 1.5–9.5?µm. The highest encapsulation efficiency of the prepared microspheres was observed in systems consisting of linalool (81.10?±?10.0?wt. % for PLA system and 76.0?±?3.3?wt. % for PMMA system). Confirmation was also made that the release rate of the microspheres was affected by the size of the same.  相似文献   

17.
18.
19.
20.
《Foot and Ankle Surgery》2020,26(2):193-197
BackgroundThe aim of this study was to compare the radiographic and functional results between fixation and non-fixation in the Cotton osteotomy for the treatment of adult acquired flatfoot.MethodsA retrospective, case-controlled study of consecutive stage IIB posterior tibial tendon dysfunction (PTTD) patients treated with the same bony reconstructive surgery including cotton osteotomy between 2013 and 2017. Meary’s angle, the medial arch sag angle (MASA), and medial cuneiform cobb angle (MCCA) were evaluated pre-operation, at first weight bearing after surgery, and 12 months post operation.ResultsForty feet were included in the study. The cotton osteotomy utilized screw fixation (n = 20) or non-fixation technique (n = 20). No significant differences between groups were found in pre-operative and follow-up radiographic parameters, union rate, and functional results.ConclusionThe non-fixation with press fit technique is a reliable procedure for Cotton osteotomy and as effective as screw fixation.Level of evidenceLevel III, case control study  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