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   16999篇
  免费   1204篇
  国内免费   42篇
耳鼻咽喉   146篇
儿科学   508篇
妇产科学   531篇
基础医学   2596篇
口腔科学   296篇
临床医学   1962篇
内科学   3207篇
皮肤病学   514篇
神经病学   1611篇
特种医学   341篇
外科学   1692篇
综合类   111篇
一般理论   38篇
预防医学   1814篇
眼科学   269篇
药学   1235篇
中国医学   26篇
肿瘤学   1348篇
  2023年   162篇
  2022年   358篇
  2021年   628篇
  2020年   326篇
  2019年   594篇
  2018年   611篇
  2017年   414篇
  2016年   519篇
  2015年   521篇
  2014年   724篇
  2013年   893篇
  2012年   1258篇
  2011年   1348篇
  2010年   738篇
  2009年   621篇
  2008年   1021篇
  2007年   1048篇
  2006年   1047篇
  2005年   961篇
  2004年   847篇
  2003年   763篇
  2002年   727篇
  2001年   176篇
  2000年   172篇
  1999年   159篇
  1998年   159篇
  1997年   107篇
  1996年   103篇
  1995年   85篇
  1994年   101篇
  1993年   62篇
  1992年   83篇
  1991年   87篇
  1990年   81篇
  1989年   70篇
  1988年   68篇
  1987年   46篇
  1986年   40篇
  1985年   62篇
  1984年   41篇
  1983年   47篇
  1982年   34篇
  1981年   41篇
  1980年   36篇
  1979年   26篇
  1978年   25篇
  1977年   28篇
  1976年   20篇
  1975年   17篇
  1974年   23篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
11.
While commercial surrogate parenting arrangements continue to flourish in the U.S., Britain has made it a criminal offense for third parties to benefit from surrogacy. Voluntary surrogacy, however is still within the law. Banning commercial surrogacy while leaving voluntary surrogacy lawful seems neither logical nor fair. A more equitable solution would be to license stringently and control both commercial and nonprofit agencies to provide these services.  相似文献   
12.
13.
OBJECTIVE: To assess the impact of activity restriction (AR) on the incidence of preterm birth in women treated for preterm labor testing negative for fetal fibronectin (fFN). STUDY DESIGN: Women who were diagnosed with preterm labor and tocolyzed with magnesium sulfate were concurrently screened with fFN for the purpose of subsequent management. Included were consenting patients with negative fFN, gestational age 23 0/7-33 6/7 weeks, cervical dilation < or =3 cm, and minimal vaginal bleeding. Patients were randomized to AR or no AR. Primary study outcome was incidence of preterm delivery and interval from randomization to delivery. RESULTS: A total of 73 women with negative fFN were randomized (36 with AR, 37 without AR). The overall preterm birth rate was 40%, with 44.4% of patients with AR and 35.1% of patients without AR delivering preterm, p=0.478. CONCLUSION: Maternal AR did not impact pregnancy outcome. The incidence of preterm birth in symptomatic women testing fFN negative was higher than previously reported.  相似文献   
14.
Insulin-like growth factor-1 (Igf-1), a critical mediator of tissue repair, is significantly decreased in diabetic wounds. Furthermore, decreased levels of hypoxia-inducible factor 1-alpha (Hif-1alpha) and its target genes are also associated with impaired wound healing in diabetic mice. The aim of our study was to examine whether the reduced levels of Igf-1 are responsible for the reduction in Hif-1alpha protein synthesis and activity in diabetic wounds. We provide evidence that Igf-1 regulates Hif-1alpha protein synthesis and activity during wound repair. In addition, Igf-1 stimulated phosphytidylinositol 3-kinase activity in diabetic fibroblasts, which, in turn, increased activation of the translational regulatory protein, p70 S6 kinase. Moreover, improved healing of diabetic wounds by addition of recombinant IGF-1 protein was associated with an increase in Hif-1alpha protein synthesis and function in vivo.  相似文献   
15.
16.
17.
18.
Fast and slow twitch muscle fibers have distinct contractile properties. Here we determined that membrane excitability also varies with fiber type. Na+ currents (INA) were studied with the loose-patch voltage clamp technique on 29 histochemically classified human intercostal skeletal muscle fibers at the endplate border and <200 μm from the endplate (extrajunctional). Fast and slow twitch fibers showed slow inactivation of endplate border and extrajunctional INA and had increased INA at the endplate border compared to extrajunctional membrane. The voltage dependencies of INA were similar on the endplate border and extrajunctional membrane, which suggests thatboth regions have physiclogically similar channels. Fast twitch fibers had larger INA on the endplate border and extrajunctional membrane and manifest fast and slow inactivation of INA at more negative potentials than slow twitch fibers. For normal muscle, the differences between INA on fast and slow twitch fibers might: (1) enable fast twitch fibers to operate at high firing frequencies for brief periods; and (2) enable slow twitch fibers to operate at low firing frequencies for prolonged times. Disorders of skeletal membrane excitability, such as the periodic paralyses and myotonias, may impact fast and slow twitch fibers differently due to the distinctive Na+ channel properties of each fiber type. © 1993 John Wiley & Sons, Inc.  相似文献   
19.
1. The effects of graded treadmill exercise on renal blood flow (RBF) were examined in seven rabbits, in which congestive heart failure (CHF) was produced by the administration of doxorubicin, 1 mg/kg, twice weekly for 8 weeks, and in seven controls. A third group of five rabbits underwent doxorubicin treatment with the addition of surgical section of the left renal sympathetic nerve. 2. During submaximal exercise, there was a small reduction in RBF in controls, which was greatly exaggerated in CHF. 3. In both control and heart failure rabbits, there was a precipitous fall in RBF as exercise fatigue developed. 4. Renal sympathectomy ablated these changes in RBF during exercise. 5. It is concluded that in heart failure there is an exaggerated, sympathetically mediated, diversion of blood flow away from the kidney. The onset of exercise fatigue in both normal and heart failure rabbits is accompanied by a marked intensification of this process.  相似文献   
20.
Recent work has demonstrated that the auditory cortex in rat sends direct projections to the auditory nuclei of the brainstem, including the cochlear nucleus and superior olive. To determine the cortical origin of the projections to cochlear nucleus, Fast Blue, a retrograde fluorescent tracer, was injected into the cochlear nucleus. Labeled cells in the forebrain were then studied with light microscopy and mapped. The projection was found to originate from large pyramidal neurons in layer V of primary auditory cortex. The projection was predominantly ipsilateral, and no labeled neurons were found in other cortical areas. These data imply that primary auditory cortex exerts influence over ascending auditory information at the earliest stages of the central auditory system.  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