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   39284篇
  免费   2709篇
  国内免费   122篇
耳鼻咽喉   366篇
儿科学   1230篇
妇产科学   1357篇
基础医学   5079篇
口腔科学   788篇
临床医学   7312篇
内科学   7052篇
皮肤病学   624篇
神经病学   3573篇
特种医学   653篇
外科学   3438篇
综合类   422篇
一般理论   55篇
预防医学   4775篇
眼科学   497篇
药学   2169篇
中国医学   69篇
肿瘤学   2656篇
  2023年   306篇
  2022年   403篇
  2021年   827篇
  2020年   534篇
  2019年   816篇
  2018年   1012篇
  2017年   731篇
  2016年   776篇
  2015年   946篇
  2014年   1324篇
  2013年   1957篇
  2012年   2748篇
  2011年   2990篇
  2010年   1675篇
  2009年   1514篇
  2008年   2671篇
  2007年   2657篇
  2006年   2679篇
  2005年   2503篇
  2004年   2401篇
  2003年   2271篇
  2002年   2112篇
  2001年   298篇
  2000年   212篇
  1999年   369篇
  1998年   476篇
  1997年   430篇
  1996年   383篇
  1995年   340篇
  1994年   314篇
  1993年   280篇
  1992年   211篇
  1991年   175篇
  1990年   172篇
  1989年   171篇
  1988年   134篇
  1987年   161篇
  1986年   125篇
  1985年   137篇
  1984年   184篇
  1983年   187篇
  1982年   219篇
  1981年   178篇
  1980年   167篇
  1979年   109篇
  1978年   81篇
  1977年   108篇
  1976年   84篇
  1975年   75篇
  1974年   82篇
排序方式: 共有10000条查询结果,搜索用时 12 毫秒
21.
In 1995, the National League for Nursing commissioned a Panel on Interdisciplinary/Transdisciplinary Education. The focus of the Panel's work was to examine educational issues that transcend the health professions and to make recommendations for future implementation of an interdisciplinary approach to addressing them. This article is being simultaneously published by several professional journals. The goal is to seek as much feedback as possible.  相似文献   
22.
A common misconception is held among many ethnic minoritiesin San Francisco that AIDS is exclusively a ‘gay whitemale disease’. This myth is false, but dangerous. To assistethnic minorities in understanding their risks for AIDS, successfuleducational programs for these populations must recognize thediversity within these communities, including their differingcultures, languages and religious backgrounds. San Franciscohas adopted a model that utilizes well-established and well-respectedcommunity-based organizations to provide the education and riskreduction programs. Utilizing these organizations allows foreducation of diverse populations that is culturally and linguisticallyrelevant, thus allowing San Francisco an opportunity to preventthe national minority AIDS statistics from occurring withinits boundaries.  相似文献   
23.
The neuropeptide neurotensin (NT) has been shown to modulate mesolimbic dopaminergic activity. Neurotensin injected into the VTA produces motor stimulation and release of dopamine in the nucleus accumbens. In contrast, when neurotensin is administered into the nucleus accumbens, it produces neuroleptic-like effects such as attenuation of the locomotor activity elicited by psychostimulants. In the present study, the hypothesis that neurotensin injected into the nucleus accumbens might modulate the psychostimulant and reinforcing actions of cocaine was tested. In experiment one, rats were trained to self-administer cocaine intravenously on an FR5 schedule of reinforcement. Following the establishment of baseline responding, rats were implanted with bilateral cannulae in the nucleus accumbens. One week later, rats were injected into the nucleus accumbens with various doses of neurotensin (4.2, 8.4 and 16.7 μg, total doses bilaterally) immediately prior to the self-administration session. No significant effects were found with any of the doses of neurotensin tested on the self-administration of cocaine. However, in experiment 2, neurotensin at doses of 4.2 and 16.7 μg injected into the nucleus accumbens significantly reduced the locomotor activation induced by an acute injection of cocaine (15 mg/kg i.p.) and a dose of 16.7 μg attenuated the locomotor activation induced by amphetamine (0.75 mg/kg i.p.). Thus, neurotensin in the nucleus accumbens appears to specifically modulate the acute locomotor activating properties of cocaine but not cocaine self-administration. Different mechanisms by which NT interacts with dopamine in the nucleus accumbens may provide a means of selectively altering psychostimulant motor actions without affecting psychostimulant reinforcement.  相似文献   
24.
Published reports of the effectiveness of preterm birth prevention programs have produced mixed results. Many larger observational studies suggest benefit. The randomized trials, however, suggest no effect on reducing rates of preterm birth in high-risk populations. This article reviews and critiques these reports and suggests areas for further research.  相似文献   
25.
26.
27.
28.
29.
Dietary supplementation with vitamin K(1), with vitamin D(3) and calcium or their combination, was examined in healthy older women during a 2-year, double-blind, placebo-controlled trial. Combined vitamin K with vitamin D plus calcium was associated with a modest but significant increase in BMC at the ultradistal radius but not at other sites in the hip or radius. INTRODUCTION: The putative beneficial role of high dietary vitamin K(1) (phylloquinone) on BMD and the possibility of interactive benefits with vitamin D were studied in a 2-year double-blind, placebo-controlled trial in healthy Scottish women > or =60 years of age. MATERIALS AND METHODS: Healthy, nonosteoporotic women (n = 244) were randomized to receive either (1) placebo, (2) 200 microg/day vitamin K(1), (3) 10 microg (400 IU) vitamin D(3) plus 1000 mg calcium/day, or (4) combined vitamins K(1) and D(3) plus calcium. Baseline and 6-month measurements included DXA bone mineral scans of the hip and wrist, markers of bone turnover, and vitamin status. Supplementation effects were tested using multivariate general linear modeling, with full adjustment for baseline and potential confounding variables. RESULTS: Significant bone mineral loss was seen only at the mid-distal radius but with no significant difference between groups. However, women who took combined vitamin K and vitamin D plus calcium showed a significant and sustained increase in both BMD and BMC at the site of the ultradistal radius. Serum status indicators responded significantly to respective supplementation with vitamins K and D. Over 2 years, serum vitamin K(1) increased by 157% (p < 0.001), the percentage of undercarboxylated osteocalcin (%GluOC) decreased by 51% (p < 0.001), serum 25-hydroxyvitamin D [25(OH)D] increased by 17% (p < 0.001), and PTH decreased by 11% (p = 0.049). CONCLUSIONS: These results provide evidence of a modest synergy in healthy older women from nutritionally relevant intakes of vitamin K(1) together with supplements of calcium plus moderate vitamin D(3) to enhance BMC at the ultradistal radius, a site consisting of principally trabecular bone. The substantial increase in gamma-carboxylation of osteocalcin by vitamin K may have long-term benefits and is potentially achievable by increased dietary intakes of vitamin K rather than by supplementation.  相似文献   
30.
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