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   189665篇
  免费   10733篇
  国内免费   534篇
耳鼻咽喉   2339篇
儿科学   5939篇
妇产科学   4165篇
基础医学   25492篇
口腔科学   8047篇
临床医学   13948篇
内科学   43287篇
皮肤病学   4789篇
神经病学   15921篇
特种医学   5715篇
外国民族医学   26篇
外科学   23752篇
综合类   1513篇
现状与发展   1篇
一般理论   65篇
预防医学   19325篇
眼科学   3483篇
药学   11496篇
中国医学   757篇
肿瘤学   10872篇
  2023年   1040篇
  2022年   2293篇
  2021年   4268篇
  2020年   2780篇
  2019年   3988篇
  2018年   5545篇
  2017年   4067篇
  2016年   3826篇
  2015年   4474篇
  2014年   6129篇
  2013年   7731篇
  2012年   12082篇
  2011年   12577篇
  2010年   6378篇
  2009年   5749篇
  2008年   9774篇
  2007年   10325篇
  2006年   9613篇
  2005年   9871篇
  2004年   9260篇
  2003年   8392篇
  2002年   6438篇
  2001年   5200篇
  2000年   5195篇
  1999年   4598篇
  1998年   1681篇
  1997年   1392篇
  1996年   1377篇
  1995年   1179篇
  1994年   1151篇
  1993年   1039篇
  1992年   2784篇
  1991年   2688篇
  1990年   2438篇
  1989年   2421篇
  1988年   2194篇
  1987年   2019篇
  1986年   1912篇
  1985年   1806篇
  1984年   1320篇
  1983年   1072篇
  1982年   618篇
  1981年   546篇
  1980年   526篇
  1979年   959篇
  1978年   637篇
  1977年   510篇
  1975年   572篇
  1974年   588篇
  1973年   602篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
1.
2.
3.
4.
Objective: Polyunsaturated fatty acids n-3 (PUFA n-3) have shown effects in reducing tumor growth, in particular eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) abundantly present in fish oil (FO). When these fatty acids are provided in the diet, they alter the functions of the cells, particularly in tumor and immune cells. However, the effects of α-linolenic fatty acid (ALA), which is the precursor of EPA and DHA, are controversial. Thus, our objective was to test the effect of this parental fatty acid. Methods: Non-tumor-bearing and tumor-bearing Wistar rats (70 days) were supplemented with 1 g/kg body weight of FO or Oro Inca® (OI) oil (rich in ALA). Immune cells function, proliferation, cytokine production, and subpopulation profile were evaluated. Results: We have shown that innate immune cells enhanced phagocytosis capacity, and increased processing and elimination of antigens. Moreover, there was a decrease in production of pro-inflammatory cytokines (tumor necrosis factor-alpha (TNF-α) and interleukin 6 (IL-6)) by macrophages. Lymphocytes showed decreased proliferation capacity, increased cluster of differentiation 8 (CD8+) subpopulation, and increased TNF-α production. Conclusions: Oil rich in ALA caused similar immune modulation in cancer when compared with FO.  相似文献   
5.
6.
7.
Farnesyltransferase (FTase) is one of the prenyltransferase family enzymes that catalyse the transfer of 15-membered isoprenoid (farnesyl) moiety to the cysteine of CAAX motif-containing proteins including Rho and Ras family of G proteins. Inhibitors of FTase act as drugs for cancer, malaria, progeria and other diseases. In the present investigation, we have developed two structure-based pharmacophore models from protein–ligand complex (3E33 and 3E37) obtained from the protein data bank. Molecular dynamics (MD) simulations were performed on the complexes, and different conformers of the same complex were generated. These conformers were undergone protein–ligand interaction fingerprint (PLIF) analysis, and the fingerprint bits have been used for structure-based pharmacophore model development. The PLIF results showed that Lys164, Tyr166, TrpB106 and TyrB361 are the major interacting residues in both the complexes. The RMSD and RMSF analyses on the MD-simulated systems showed that the absence of FPP in the complex 3E37 has significant effect in the conformational changes of the ligands. During this conformational change, some interactions between the protein and the ligands are lost, but regained after some simulations (after 2 ns). The structure-based pharmacophore models showed that the hydrophobic and acceptor contours are predominantly present in the models. The pharmacophore models were validated using reference compounds, which significantly identified as HITs with smaller RMSD values. The developed structure-based pharmacophore models are significant, and the methodology used in this study is novel from the existing methods (the original X-ray crystallographic coordination of the ligands is used for the model building). In our study, along with the original coordination of the ligand, different conformers of the same complex (protein–ligand) are used. It concluded that the developed methodology is significant for the virtual screening of novel molecules on different targets.  相似文献   
8.
9.
10.
Anomalous origin of the left coronary artery from the pulmonary artery (ALCAPA) is a rare congenital condition. It responds well to early diagnosis and treatment, but otherwise the prognosis is poor. We present our case series of 12 patients (mean age, 2 ± 2.58 yr; age range, 2 mo–8 yr), emphasizing the diagnostic process and discussing our surgical results. The diagnosis of ALCAPA should be suspected in infants who have dilated cardiomyopathy with electrocardiographic changes that suggest ischemia, and in older children who have isolated mitral regurgitation. When clinical suspicion is high, the results of 2-dimensional echocardiography combined with color-flow Doppler studies in expert hands can establish the diagnosis, thus avoiding angiography in critically ill infants. The treatment of choice in our patients was transfer and reimplantation of the left coronary artery onto the ascending aorta. There were 2 deaths: both were infants in extremis who underwent emergency surgery. An older child with severe ventricular dysfunction was given mechanical ventricular assistance and then heart transplantation. As of this report, all 10 survivors remained well and asymptomatic.  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