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   1638318篇
  免费   124666篇
  国内免费   3881篇
耳鼻咽喉   23618篇
儿科学   50152篇
妇产科学   47884篇
基础医学   233768篇
口腔科学   47292篇
临床医学   139920篇
内科学   321943篇
皮肤病学   34077篇
神经病学   131926篇
特种医学   66366篇
外国民族医学   490篇
外科学   257625篇
综合类   40345篇
现状与发展   2篇
一般理论   494篇
预防医学   123215篇
眼科学   38213篇
药学   119927篇
中国医学   3174篇
肿瘤学   86434篇
  2018年   15331篇
  2015年   15370篇
  2014年   22027篇
  2013年   33923篇
  2012年   45292篇
  2011年   47993篇
  2010年   28643篇
  2009年   27143篇
  2008年   45753篇
  2007年   49259篇
  2006年   49176篇
  2005年   48467篇
  2004年   46916篇
  2003年   45417篇
  2002年   44114篇
  2001年   71047篇
  2000年   72819篇
  1999年   61956篇
  1998年   17989篇
  1997年   16492篇
  1996年   16246篇
  1995年   15299篇
  1994年   14630篇
  1993年   13737篇
  1992年   50563篇
  1991年   48962篇
  1990年   47986篇
  1989年   46253篇
  1988年   43199篇
  1987年   42536篇
  1986年   40671篇
  1985年   39035篇
  1984年   29760篇
  1983年   25410篇
  1982年   15762篇
  1981年   14194篇
  1980年   13425篇
  1979年   29039篇
  1978年   20715篇
  1977年   17467篇
  1976年   16303篇
  1975年   17767篇
  1974年   21699篇
  1973年   20749篇
  1972年   19744篇
  1971年   18250篇
  1970年   17488篇
  1969年   16665篇
  1968年   15470篇
  1967年   14238篇
排序方式: 共有10000条查询结果,搜索用时 491 毫秒
91.
Background Immune checkpoint blockers (ICBs) activate CD8+ T cells, eliciting both anti-cancer activity and immune-related adverse events (irAEs). The relationship of irAEs with baseline parameters and clinical outcome is unclear.Methods Retrospective evaluation of irAEs on survival was performed across primary (N = 144) and secondary (N = 211) independent cohorts of patients with metastatic melanoma receiving single agent (pembrolizumab/nivolumab—sICB) or combination (nivolumab and ipilimumab—cICB) checkpoint blockade. RNA from pre-treatment and post-treatment CD8+ T cells was sequenced and differential gene expression according to irAE development assessed.Results 58.3% of patients developed early irAEs and this was associated with longer progression-free (PFS) and overall survival (OS) across both cohorts (log-rank test, OS: P < 0.0001). Median survival for patients without irAEs was 16.6 months (95% CI: 10.9–33.4) versus not-reached (P = 2.8 × 10−6). Pre-treatment monocyte and neutrophil counts, but not BMI, were additional predictors of clinical outcome. Differential expression of numerous gene pathway members was observed in CD8+ T cells according to irAE development, and patients not developing irAEs demonstrating upregulated CXCR1 pre- and post-treatment.Conclusions Early irAE development post-ICB is associated with favourable survival in MM. Development of irAEs is coupled to expression of numerous gene pathways, suggesting irAE development in-part reflects baseline immune activation.Subject terms: Immunotherapy, Melanoma  相似文献   
92.
93.
94.
95.
96.
97.
98.
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   
99.
100.

Background

Arterial vascular anomalies in patients undergoing kidney transplantation (KT) are correlated with a higher incidence of early surgical complications, potentially causing graft loss. Arterial reconstruction allows patients to overcome these surgical challenges, thus minimizing the risk of poor outcomes. The aim of the present study is to retrospectively investigate the safety and effectiveness of the multiple arterial reconstruction technique with a Teflon patch in case of an unavailable aortic patch: to do so, surgical complications, graft function, and patient survival were evaluated.

Methods

During the period January 2009 to August 2016, 202 adult deceased-donor KTs were performed at our center. Group A (n = 27; reconstruction of multiple arteries) and Group B (n = 175; control group) were compared.

Results

No differences were observed between the 2 groups in terms of early postoperative course, with no vascular complication observed in Group A. No vascular patch infections were reported, nor longer cold ischemia time rates. Similarly, long-term survival rates were similar between the 2 groups.

Conclusions

The Teflon-patch arterial reconstruction technique appears to be safe and effective, with an acceptable balance of benefits and potential risks of using a prosthetic material. Studies based on larger series are needed to further validate this approach.  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