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   8622篇
  免费   679篇
  国内免费   19篇
耳鼻咽喉   76篇
儿科学   267篇
妇产科学   178篇
基础医学   1153篇
口腔科学   115篇
临床医学   1563篇
内科学   1470篇
皮肤病学   88篇
神经病学   802篇
特种医学   167篇
外科学   646篇
综合类   113篇
一般理论   10篇
预防医学   1431篇
眼科学   112篇
药学   549篇
中国医学   1篇
肿瘤学   579篇
  2023年   95篇
  2022年   85篇
  2021年   159篇
  2020年   137篇
  2019年   220篇
  2018年   222篇
  2017年   202篇
  2016年   188篇
  2015年   239篇
  2014年   323篇
  2013年   442篇
  2012年   685篇
  2011年   678篇
  2010年   346篇
  2009年   303篇
  2008年   553篇
  2007年   598篇
  2006年   566篇
  2005年   598篇
  2004年   507篇
  2003年   552篇
  2002年   488篇
  2001年   66篇
  2000年   48篇
  1999年   77篇
  1998年   110篇
  1997年   74篇
  1996年   55篇
  1995年   55篇
  1994年   60篇
  1993年   64篇
  1992年   35篇
  1991年   35篇
  1990年   25篇
  1989年   28篇
  1988年   33篇
  1987年   24篇
  1986年   30篇
  1985年   29篇
  1984年   40篇
  1983年   32篇
  1982年   28篇
  1981年   31篇
  1980年   27篇
  1979年   11篇
  1978年   14篇
  1977年   11篇
  1976年   11篇
  1975年   11篇
  1973年   12篇
排序方式: 共有9320条查询结果,搜索用时 78 毫秒
991.
992.
Animal research together with other investigational methods (computer modeling, in vitro tests, etc) remains an indispensable part of the pharmaceutical research and development process. The European pharmaceutical industry recognizes the responsibilities inherent in animal research and is committed to applying and enhancing 3Rs principles. New nonsentient, ex vivo, and in vitro methods are developed every day and contribute to reducing and, in some instances, replacing in vivo studies. Their utility is however limited by the extent of our current knowledge and understanding of complex biological systems. Until validated alternative ways to model these complex interactions become available, animals remain indispensable in research and safety testing. In the interim, scientists continue to look for ways to reduce the number of animals needed to obtain valid results, refine experimental techniques to enhance animal welfare, and replace animals with other research methods whenever feasible. As research goals foster increasing cross-sector and international collaboration, momentum is growing to enhance and coordinate scientific innovation globally—beyond a single company, stakeholder group, sector, region, or country. The implementation of 3Rs strategies can be viewed as an integral part of this continuously evolving science, demonstrating the link between science and welfare, benefiting both the development of new medicines and animal welfare. This goal is one of the key objectives of the Research and Animal Welfare working group of the European Federation of Pharmaceutical Industries and Associations.Abbreviations: EFPIA, European Federation of Pharmaceutical Industries and Associations; EPAA, European Partnership for Alternative Approaches to Animal Testing; EU, European Union; IMI, Innovative Medicines Initiative; NC3Rs, National Centre for the 3Rs; RAW, Research and Animal Welfare  相似文献   
993.
994.
Lymphotoxin α (LTα) plays a key role in the formation of lymphatic vasculature and secondary lymphoid structures. Cutaneous T cell lymphoma (CTCL) is the most common primary lymphoma of the skin and in advanced stages, malignant T cells spreads through the lymphatic to regional lymph nodes to internal organs and blood. Yet, little is known about the mechanism of the CTCL dissemination. Here, we show that CTCL cells express LTα in situ and that LTα expression is driven by aberrantly activated JAK3/STAT5 pathway. Importantly, via TNF receptor 2, LTα functions as an autocrine factor by stimulating expression of IL-6 in the malignant cells. LTα and IL-6, together with VEGF promote angiogenesis by inducing endothelial cell sprouting and tube formation. Thus, we propose that LTα plays a role in malignant angiogenesis and disease progression in CTCL and may serve as a therapeutic target in this disease.  相似文献   
995.
996.
997.
998.
To study the feasibility of endovascular management of early hepatic artery thrombosis (HAT) after living‐donor liver transplantation (LDLT) and to clarify its role as a less invasive alternative to open surgery. A retrospective review of 360 recipients who underwent LDLT. Early HAT developed in 13 cases (3.6%). Diagnosis was performed using Doppler, CT angiography, and digital subtraction angiography. Intra‐arterial thrombolysis (IAT) was performed using streptokinase or tPA. In case of underlying stricture, PTA was attempted. If the artery did not recanalize, continuous infusion was performed and monitored using Doppler US. Initial surgical revascularization was successful in 2/13 cases. IAT was performed in 11/13 cases. The initial success rate was 81.8% (9/11), the failure rate was 18.2% (2/11). Rebound thrombosis developed in 33.3% (3/9). Hemorrhage developed after IAT in 2/11 cases (18.2%). Definite endovascular treatment of HAT was achieved in 6/11 cases (54.5%) and definite treatment (surgical, endovascular or combined) in 9/13 cases (69%). (Follow‐up 4 months–4 years). Endovascular management of early HAT after LDLT is a feasible and reliable alternative to open surgery. It plays a role as a less invasive approach with definite endovascular treatment rate of 54.5%.  相似文献   
999.
1000.

Background

Despite a large number of clinical trials having been conducted to assess the efficacy of adjuvant chemotherapy after surgery for various cancers, whether it is best to use this treatment remains a generally contentious issue for many common cancers. The purpose of this study was to ascertain whether any general conclusions can be drawn about the efficacy or inefficacy of this treatment within different cancer classifications.

Methods

Meta-analyses of randomized, controlled trials (RCTs) of adjuvant chemotherapy after surgery were synthesized over as many types of cancer as possible. Data sources were Medline, Embase, and the Cochrane library. Eligible meta-analyses were meta-analyses of RCTs for any type of cancer that compared surgery followed by adjuvant chemotherapy with surgery followed by no adjuvant chemotherapy.

Results

The literature search found 25 meta-analyses for 15 cancer types that satisfied the criteria necessary for detailed analysis within this study. The estimates of relative risk for all cause mortality were reported as being less than one (indicating adjuvant chemotherapy is beneficial) by all meta-analyses apart from a meta-analysis for colorectal cancer metastasized to the liver. Moreover, 15 of these meta-analyses also reported that the 95?% confidence interval for this relative risk is less than one (indicating statistical significance at the 5?% level).

Conclusions

The results for all cancer types included in this study except for cancer metastasized to the liver can be thought of as supporting each other through the idea of there being a common treatment effect or at least a common range of effect across all (or most) of these cancer types. For example, with regard to cancer types where the evidence in favor of adjuvant chemotherapy after surgery is only moderately strong, the results of this study may encourage more clinicians to regard the use of this treatment as standard practice.  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