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   3476939篇
  免费   284383篇
  国内免费   13982篇
耳鼻咽喉   48594篇
儿科学   111407篇
妇产科学   90881篇
基础医学   549474篇
口腔科学   93731篇
临床医学   308781篇
内科学   615929篇
皮肤病学   91632篇
神经病学   294677篇
特种医学   137518篇
外国民族医学   391篇
外科学   542915篇
综合类   102903篇
现状与发展   23篇
一般理论   2241篇
预防医学   290275篇
眼科学   79514篇
药学   241106篇
  23篇
中国医学   9809篇
肿瘤学   163480篇
  2021年   55317篇
  2020年   35281篇
  2019年   58385篇
  2018年   71727篇
  2017年   54569篇
  2016年   60240篇
  2015年   74465篇
  2014年   108818篇
  2013年   174243篇
  2012年   92499篇
  2011年   92850篇
  2010年   117176篇
  2009年   121598篇
  2008年   80617篇
  2007年   84194篇
  2006年   94728篇
  2005年   90643篇
  2004年   92309篇
  2003年   83513篇
  2002年   73769篇
  2001年   104562篇
  2000年   97302篇
  1999年   97514篇
  1998年   65416篇
  1997年   63053篇
  1996年   61020篇
  1995年   56450篇
  1994年   50725篇
  1993年   47202篇
  1992年   69674篇
  1991年   66886篇
  1990年   64267篇
  1989年   63421篇
  1988年   59401篇
  1987年   57830篇
  1986年   55170篇
  1985年   55137篇
  1984年   49721篇
  1983年   45764篇
  1982年   42202篇
  1981年   39686篇
  1980年   37382篇
  1979年   41838篇
  1978年   36480篇
  1977年   33442篇
  1976年   30795篇
  1975年   30043篇
  1974年   31266篇
  1973年   30065篇
  1972年   28344篇
排序方式: 共有10000条查询结果,搜索用时 5 毫秒
31.
32.
33.
Geneticists have, for years, understood the nature of genome‐wide association studies using common genomic variants. Recently, however, focus has shifted to the analysis of rare variants. This presents potential problems for researchers, as rare variants do not always behave in the same way common variants do, sometimes rendering decades of solid intuition moot. In this paper, we present examples of the differences between common and rare variants. We show why one must be significantly more careful about the origin of rare variants, and how failing to do so can lead to highly inflated type I error. We then explain how to best avoid such concerns with careful understanding and study design. Additionally, we demonstrate that a seemingly low error rate in next‐generation sequencing can dramatically impact the false‐positive rate for rare variants. This is due to the fact that rare variants are, by definition, seen infrequently, making it hard to distinguish between errors and real variants. Compounding this problem is the fact that the proportion of errors is likely to get worse, not better, with increasing sample size. One cannot simply scale their way up in order to solve this problem. Understanding these potential pitfalls is a key step in successfully identifying true associations between rare variants and diseases.  相似文献   
34.
There is a large and growing population of long-term cancer survivors. Primary care physicians (PCPs) are playing an increasingly greater role in the care of these patients across the continuum of cancer survivorship. In this role, PCPs are faced with the responsibility of managing a range of medical and psychosocial late effects of cancer treatment. In particular, the sexual side effects of treatment which are common and have significant impact on quality of life for the cancer survivor, often go unaddressed. This is an area of clinical care and research that has received increasing attention, highlighted by the presentation of this special issue on Cancer and Sexual Health. The aims of this review are 3-fold. First, we seek to overview common presentations of sexual dysfunction related to major cancer diagnoses in order to give the PCP a sense of the medical issues that the survivor may present with. Barriers to communication about sexual health issues between patient/PCPs in order are also described in order to emphasize the importance of PCPs initiating this important conversation. Next, we provide strategies and resources to help guide the PCP in the management of sexual dysfunction in cancer survivors. Finally, we discuss case examples of survivorship sexual health issues and highlight the role that a PCP can play in each of these case examples.  相似文献   
35.
36.

Background

Limited data exists demonstrating the efficacy of minimally invasive surgery (MIS) compared to median sternotomy (MS) for multiple valvular disease (MVD). This systematic review and meta-analysis aims to compare operative and peri-operative outcomes of MIS vs MS in MVD.

Methods

PubMed, Ovid, and Embase were searched from inception until August 2019 for randomized and observational studies comparing MIS and MS in patients with MVD. Clinical outcomes of intra- and postoperative times, reoperation for bleeding and surgical site infection were evaluated.

Results

Five observational studies comparing 340 MIS vs 414 MS patients were eligible for qualitative and quantitative review. The quality of evidence assessed using the Newcastle-Ottawa scale was good for all included studies. Meta-analysis demonstrated increased cardiopulmonary bypass time for MIS patients (weighted mean difference [WMD], 0.487; 95% confidence interval [CI], 0.365-0.608; P < .0001). Similarly, aortic cross-clamp time was longer in patients undergoing MIS (WMD, 0.632; 95% CI, 0.509-0.755; P < .0001). No differences were found in operative mortality, reoperation for bleeding, surgical site infection, or hospital stay.

Conclusions

MIS for MVD have similar short-term outcomes compared to MS. This adds value to the use of minimally invasive methods for multivalvular surgery, despite conferring longer operative times. However, the paucity in literature and learning curve associated with MIS warrants further evidence, ideally randomized control trials, to support these findings.
  相似文献   
37.
38.
39.
ABSTRACT

Objective

To investigate primary care physician clinical practice patterns, barriers, and education surrounding pediatric physical activity (PA), and to compare practice patterns by discipline.  相似文献   
40.
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