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   207172篇
  免费   15269篇
  国内免费   4877篇
耳鼻咽喉   1537篇
儿科学   2991篇
妇产科学   3450篇
基础医学   25821篇
口腔科学   3583篇
临床医学   15787篇
内科学   26430篇
皮肤病学   2442篇
神经病学   18612篇
特种医学   7822篇
外国民族医学   5篇
外科学   17305篇
综合类   27603篇
现状与发展   21篇
一般理论   8篇
预防医学   16257篇
眼科学   2813篇
药学   27094篇
  70篇
中国医学   13064篇
肿瘤学   14603篇
  2024年   398篇
  2023年   2627篇
  2022年   6032篇
  2021年   8429篇
  2020年   7003篇
  2019年   7001篇
  2018年   7030篇
  2017年   7757篇
  2016年   7801篇
  2015年   7342篇
  2014年   8613篇
  2013年   13127篇
  2012年   10365篇
  2011年   12365篇
  2010年   7981篇
  2009年   8134篇
  2008年   9586篇
  2007年   10636篇
  2006年   9991篇
  2005年   9248篇
  2004年   7950篇
  2003年   7181篇
  2002年   5620篇
  2001年   5078篇
  2000年   4261篇
  1999年   3619篇
  1998年   2908篇
  1997年   2957篇
  1996年   2716篇
  1995年   2415篇
  1994年   2266篇
  1993年   1895篇
  1992年   1741篇
  1991年   1625篇
  1990年   1417篇
  1989年   1167篇
  1988年   1098篇
  1987年   1034篇
  1986年   949篇
  1985年   1349篇
  1984年   1126篇
  1983年   823篇
  1982年   870篇
  1981年   745篇
  1980年   683篇
  1979年   535篇
  1978年   328篇
  1977年   279篇
  1976年   264篇
  1975年   197篇
排序方式: 共有10000条查询结果,搜索用时 46 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.
16.
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   
17.
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   

18.
19.
20.
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