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   855篇
  免费   72篇
  国内免费   16篇
耳鼻咽喉   7篇
儿科学   79篇
妇产科学   9篇
基础医学   76篇
口腔科学   12篇
临床医学   106篇
内科学   210篇
皮肤病学   15篇
神经病学   50篇
特种医学   86篇
外科学   85篇
综合类   26篇
一般理论   6篇
预防医学   81篇
眼科学   3篇
药学   49篇
肿瘤学   43篇
  2021年   14篇
  2019年   8篇
  2018年   9篇
  2017年   10篇
  2016年   10篇
  2015年   14篇
  2014年   21篇
  2013年   27篇
  2012年   19篇
  2011年   30篇
  2010年   18篇
  2009年   21篇
  2008年   24篇
  2007年   34篇
  2006年   16篇
  2005年   25篇
  2004年   19篇
  2003年   23篇
  2002年   16篇
  2001年   15篇
  2000年   22篇
  1999年   22篇
  1998年   18篇
  1997年   23篇
  1996年   27篇
  1995年   21篇
  1994年   21篇
  1993年   14篇
  1992年   15篇
  1991年   11篇
  1990年   27篇
  1989年   29篇
  1988年   23篇
  1987年   19篇
  1986年   16篇
  1985年   15篇
  1984年   10篇
  1983年   18篇
  1982年   14篇
  1981年   12篇
  1979年   16篇
  1978年   9篇
  1977年   15篇
  1976年   9篇
  1975年   14篇
  1974年   12篇
  1973年   20篇
  1972年   9篇
  1970年   8篇
  1967年   17篇
排序方式: 共有943条查询结果,搜索用时 15 毫秒
1.
Using data on waterfowl band recoveries, we identified spatially explicit hotspots of concentrated waterfowl movement to predict occurrence and spatial spread of a novel influenza A virus (clade 2.3.4.4) introduced from Asia by waterfowl from an initial outbreak in North America in November 2014. In response to the outbreak, the hotspots of waterfowl movement were used to help guide sampling for clade 2.3.4.4 viruses in waterfowl as an early warning for the US poultry industry during the outbreak . After surveillance sampling of waterfowl, we tested whether there was greater detection of clade 2.3.4.4 viruses inside hotspots. We found that hotspots defined using kernel density estimates of waterfowl band recoveries worked well in predicting areas with higher prevalence of the viruses in waterfowl. This approach exemplifies the value of ecological knowledge in predicting risk to agricultural security.  相似文献   
2.
PURPOSE: Concern over stigma as a consequence of genetic testing has grown in response to the recent increase in genetic research and testing resulting from the Human Genome Project. However, whether a genetic or hereditary basis necessarily confers a stigma to a condition remains unexamined. METHODS: We performed a qualitative interview study with 86 individuals with one of four conditions: deafness or hearing loss, breast cancer, sickle cell disease, and cystic fibrosis. The first two groups were divided approximately between people who ascribed their conditions to a genetic or hereditary cause and those who did not. RESULTS: Respondents interpreted genetic or hereditary causes and nongenetic causes in a variety of ways. Subjects with breast cancer reported the most consistently negative interpretation of genetic cause. This response concerned future ill health, not an enduring sense of stigma. Deaf and hard of hearing subjects provided the most consistently positive comments about a genetic or hereditary basis to their condition, casting familial hearing loss as a vital component of group and individual identity. Respondents with sickle cell disease and cystic fibrosis offered similar and positive interpretations of the genetic cause of their condition insofar as it meant their conditions were not contagious. CONCLUSIONS: Although some subjects report feeling stigmatized as a result of their condition, this stigmatization is not uniformly associated with the condition's cause, genetic or otherwise. Instead, stigma emerges from a variety of sources in the context of the lived experience of a particular condition.  相似文献   
3.
麦冬类中药组织切片计算机三维重建图鉴   总被引:9,自引:0,他引:9  
利用计算机技术实现麦冬类中药组织连续切片三维重建与动态显示,为计算机辅助生药学鉴定和教学提供了新的三维图像技术和研究资料。  相似文献   
4.
5.
Abdominal trauma and diagnostic peritoneal lavage revisited   总被引:3,自引:0,他引:3  
  相似文献   
6.
Gastroesophageal reflux disease (GERD) is the most common disease of the upper gastrointestinal tract. With the introduction of proton pump inhibitors medical treatment of GERD has been significantly improved. However, the development of laparoscopic antireflux surgery resulted in an increasing interest of surgeons in this disease. An interactive meeting was organized in order to develop an agreement between gastoenterologists and surgeons regarding therapeutic decisions and this is the main topic of this paper.  相似文献   
7.
Women wish to continue to be sexually active long after their desire to bear children. The risks associated with unintended pregnancy easily can be avoided by providing women with information about, and access to, contraceptives that are safe and effective. Because fertility naturally declines with age, different contraceptives may be more suitable for women toward the end of their reproductive years than were appropriate at periods of peak fertility. This article discusses the risks and benefits of various contraceptives for midlife women and the implications of this information on nursing practice.  相似文献   
8.
9.
Summary The induction time for amorphous calcium phosphate (ACP) phase transformation was monitored at pH 7.4 and T=25°C with [Ca2+]0=[PO4]0=4.0×10−3 M, as a function of added crystal growth inhibitors Mg2+, Sr2+, Zn2+, pyrophosphate (PP), and tripolyphosphate (TPP). Metal ions increase the induction time for the initiation of the phase change reaction in the order Zn2+<Sr2+<Mg2+. For polyphosphates it was observed that both PP and TPP are potent inhibitors with TPP more effective than PP as expected. The combination of Mg2+ or Sr2+ and PP or TPP leads to a synergistic delay in the onset of the phase conversion. The greatest inhibition was observed for Mg2+ and TPP. Reaction solutions containing 2.0×10−4 M Mg2+ and 4.0×10−5 M TPP resulted in a 90% increase in the induction time over what would be anticipated from an additive effect from these species.  相似文献   
10.
Low-artifact intravascular devices: MR imaging evaluation   总被引:2,自引:0,他引:2  
Flow-phantom magnetic resonance (MR) imaging, with use of both spin-echo (SE) and gradient-echo (GRE) techniques at 1.5 T, was performed on the percutaneous Greenfield (beta-III titanium alloy [TMA wire]), Amplatz (MP32-N alloy), and Simon nitinol filters and TMA wire facsimiles of the bird's nest, Gunther, new retrievable, and Amplatz vena caval filters. SE imaging allowed detection of thrombi as small as 5 X 5 mm trapped within the percutaneous Greenfield, Simon nitinol, and TMA-wire facsimile filters; with the MP32-N Amplatz filter, a larger volume of thrombus (10 X 20-mm clots) was necessary for clot detection. GRE imaging allowed detection of intraluminal tilting of the percutaneous Greenfield and facsimile Amplatz (TMA-wire) filters. GRE imaging was useful for demonstrating postfilter turbulence due to clots, which was greatest for the Amplatz filter. Imaging of facsimile vascular devices made of tantalum or TMA wire did not cause the severe "black-hole" MR artifacts typical of the stainless-steel devices. SE and GRE imaging were very useful for determining caval patency in two patients with previously placed Mobin-Uddin filters. Noninvasive MR evaluation of blood vessels in the presence of a variety of low-artifact intravascular devices appears feasible.  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