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   240838篇
  免费   5752篇
  国内免费   164篇
耳鼻咽喉   1976篇
儿科学   8395篇
妇产科学   4610篇
基础医学   27125篇
口腔科学   3273篇
临床医学   18554篇
内科学   44103篇
皮肤病学   1706篇
神经病学   22950篇
特种医学   11623篇
外国民族医学   45篇
外科学   37300篇
综合类   2853篇
一般理论   87篇
预防医学   22986篇
眼科学   3941篇
药学   14173篇
中国医学   792篇
肿瘤学   20262篇
  2021年   1008篇
  2020年   723篇
  2019年   1036篇
  2018年   23041篇
  2017年   18128篇
  2016年   20372篇
  2015年   2095篇
  2014年   2271篇
  2013年   3295篇
  2012年   10205篇
  2011年   24259篇
  2010年   21063篇
  2009年   13448篇
  2008年   22401篇
  2007年   24740篇
  2006年   3677篇
  2005年   5171篇
  2004年   6407篇
  2003年   7066篇
  2002年   5262篇
  2001年   2446篇
  2000年   2628篇
  1999年   2118篇
  1998年   985篇
  1997年   870篇
  1996年   662篇
  1995年   787篇
  1994年   675篇
  1993年   683篇
  1992年   1516篇
  1991年   1502篇
  1990年   1496篇
  1989年   1426篇
  1988年   1173篇
  1987年   1155篇
  1986年   1091篇
  1985年   1027篇
  1984年   727篇
  1983年   687篇
  1982年   503篇
  1981年   463篇
  1980年   428篇
  1979年   644篇
  1978年   391篇
  1977年   373篇
  1975年   389篇
  1974年   446篇
  1973年   357篇
  1972年   351篇
  1971年   311篇
排序方式: 共有10000条查询结果,搜索用时 265 毫秒
1.
2.
3.
4.
5.
6.
Clinical Oral Investigations - The aim of this study was the analysis of WNT10A variants in seven families of probands with various forms of tooth agenesis and self-reported family history of...  相似文献   
7.
ABSTRACT

The average amount of sleep people of all ages get has declined sharply in the past 50 years. The detrimental health effects of sleep deprivation are well documented and substantial. Even though electronic media use often takes place in the hours before sleep, the extent to which media use may interact with sleep is understudied and not well understood. Communication scholars are well positioned to contribute to this area, as a systematic, theoretical understanding of the relationship between media and sleep is still lacking. This primer charts the state of knowledge on electronic media and sleep and explores possible next steps. First, we introduce the problem of sleep deprivation and describe the basic science of sleep with relevant terminology. Then, we review the research on electronic media and sleep and offer an agenda for research.  相似文献   
8.
Ductal carcinoma in situ (DCIS) of the breast is a nonobligate precursor of invasive breast cancer, accounting for 20 % of screen-detected breast cancers. Little is known about the natural progression of DCIS because most patients undergo surgery upon diagnosis. Many DCIS patients are likely being overtreated, as it is believed that only around 50 % of DCIS will progress to invasive carcinoma. Robust prognostic markers for progression to invasive carcinoma are lacking. In the past, studies have investigated women who developed a recurrence after breast-conserving surgery (BCS) and compared them with those who did not. However, where there is no recurrence, the patient has probably been adequately treated. The present narrative review advocates a new research strategy, wherein only those patients with a recurrence are studied. Approximately half of the recurrences are invasive cancers, and half are DCIS. So-called “recurrences” are probably most often the result of residual disease. The new approach allows us to ask: why did some residual DCIS evolve to invasive cancers and others not? This novel strategy compares the group of patients that developed in situ recurrence with the group of patients that developed invasive recurrence after BCS. The differences between these groups could then be used to develop a robust risk stratification tool. This tool should estimate the risk of synchronous and metachronous invasive carcinoma when DCIS is diagnosed in a biopsy. Identification of DCIS patients at low risk for developing invasive carcinoma will individualize future therapy and prevent overtreatment.  相似文献   
9.
10.

Background

The randomized EXCEL (Evaluation of XIENCE versus Coronary Artery Bypass Surgery for Effectiveness of Left Main Revascularization) trial reported a similar rate of the 3-year composite primary endpoint of death, myocardial infarction (MI), or stroke in patients with left main coronary artery disease (LMCAD) and site-assessed low or intermediate SYNTAX scores treated with percutaneous coronary intervention (PCI) and coronary artery bypass grafting (CABG). Whether these results are consistent in high-risk patients with diabetes, who have fared relatively better with CABG in most prior trials, is unknown.

Objectives

In this pre-specified subgroup analysis from the EXCEL trial, the authors sought to examine the effect of diabetes in patients with LMCAD treated with PCI versus CABG.

Methods

Patients (N = 1,905) with LMCAD and site-assessed low or intermediate CAD complexity (SYNTAX scores ≤32) were randomized 1:1 to PCI with everolimus-eluting stents versus CABG, stratified by the presence of diabetes. The primary endpoint was the rate of a composite of all-cause death, stroke, or MI at 3 years. Outcomes were examined in patients with (n = 554) and without (n = 1,350) diabetes.

Results

The 3-year composite primary endpoint was significantly higher in diabetic compared with nondiabetic patients (20.0% vs. 12.9%; p < 0.001). The rate of the 3-year primary endpoint was similar after treatment with PCI and CABG in diabetic patients (20.7% vs. 19.3%, respectively; hazard ratio: 1.03; 95% confidence interval: 0.71 to 1.50; p = 0.87) and nondiabetic patients (12.9% vs. 12.9%, respectively; hazard ratio: 0.98; 95% confidence interval: 0.73 to 1.32; p = 0.89). All-cause death at 3 years occurred in 13.6% of PCI and 9.0% of CABG patients (p = 0.046), although no significant interaction was present between diabetes status and treatment for all-cause death (p = 0.22) or other endpoints, including the 3-year primary endpoint (p = 0.82) or the major secondary endpoints of death, MI, or stroke at 30 days (p = 0.61) or death, MI, stroke, or ischemia-driven revascularization at 3 years (p = 0.65).

Conclusions

In the EXCEL trial, the relative 30-day and 3-year outcomes of PCI with everolimus-eluting stents versus CABG were consistent in diabetic and nondiabetic patients with LMCAD and site-assessed low or intermediate SYNTAX scores.(Evaluation of XIENCE versus Coronary Artery Bypass Surgery for Effectiveness of Left Main Revascularization [EXCEL]; NCT01205776)  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