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   25843篇
  免费   8390篇
  国内免费   177篇
耳鼻咽喉   224篇
儿科学   673篇
妇产科学   502篇
基础医学   5101篇
口腔科学   995篇
临床医学   3979篇
内科学   6408篇
皮肤病学   550篇
神经病学   1973篇
特种医学   1917篇
外科学   5945篇
综合类   312篇
一般理论   11篇
预防医学   2892篇
眼科学   425篇
药学   1324篇
  2篇
中国医学   11篇
肿瘤学   1166篇
  2021年   355篇
  2020年   271篇
  2018年   352篇
  2017年   379篇
  2016年   553篇
  2015年   885篇
  2014年   1489篇
  2013年   2122篇
  2012年   669篇
  2011年   581篇
  2010年   1195篇
  2009年   1312篇
  2008年   534篇
  2007年   327篇
  2006年   455篇
  2005年   375篇
  2004年   340篇
  2003年   280篇
  2002年   318篇
  2001年   462篇
  2000年   388篇
  1999年   588篇
  1998年   879篇
  1997年   842篇
  1996年   894篇
  1995年   828篇
  1994年   706篇
  1993年   651篇
  1992年   622篇
  1991年   590篇
  1990年   522篇
  1989年   635篇
  1988年   657篇
  1987年   651篇
  1986年   579篇
  1985年   633篇
  1984年   558篇
  1983年   541篇
  1982年   601篇
  1981年   566篇
  1980年   536篇
  1979年   513篇
  1978年   509篇
  1977年   511篇
  1976年   446篇
  1975年   398篇
  1974年   357篇
  1973年   336篇
  1972年   337篇
  1971年   309篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
32.
33.
34.
35.
The intrauterine position occupied by a rodent fetus influences the amount of testosterone to which it is exposed before birth. Animals that are gestated between two male fetuses (2M) are exposed to higher circulating levels of testosterone than are animals positioned between two female fetuses (2F) and there are reliable differences in the reproductive physiology and behavior of 2M and 2F animals when adult. To determine whether intrauterine position modifies development of the central nervous system, we examined the sexually dimorphic spinal nucleus of the bulbocavernosus (SNB) in male and female gerbils from known intrauterine positions. We found that adult 2M female gerbils had 16% more SNB motoneurons than did 2F females. 2M males did not differ from 2F males in SNB motoneuron number, but the bulbocavernosus muscle, which is innervated by SNB motoneurons, was approximately 50% larger in 2M than in 2F males. These data indicate that intrauterine position can influence the morphology of the sexually dimorphic SNB neuromuscular system.  相似文献   
36.
A 7-cm anterior mediastinal tumor in an 80-year-old woman was found by light and electron microscopy to be a neuroblastoma. Immunoreactivity for neuron-specific enolase, synaptophysin, and chromogranin supported the diagnosis. Neuroblastoma is an uncommon tumor in adults and we are not aware of a previous report of such a tumor in a patient of this age.  相似文献   
37.
38.
The aim of the study was the investigation of the biochemical condition of elements likely to directly participate in active closing of the urethral lumen. We estimated glycogenolysis in urinary bladder, perivesical connective tissue and levator ani muscle (LAM) samples obtained intraoperatively from 80 stress incontinent women. Glycogen content as well as activities of active and total glycogen phosphorylase and acid exo-1,4-alpha-glucosidase were measured. Material from the urinary bladder and perivesical connective tissue was insignificantly altered, and glycogen contents in the bladder (2.03±1.38 g/100 g wet tissue) were considered to be normal. In the LAM glycogenolysis was much more activated than in other tissues (p<0.001 by Fischer's exact test). Of LAM specimens 78% (22/28) revealed imbalanced biochemistry of glycogen with activation of hydrolytic decomposition. We conclude that stress urinary incontinence in women is frequently associated with metabolic alterations in the periurethral striated fibres. This study indirectly supports our recent hypothesis on the pathogenesis of the disease in terms of muscle fibre type transitions.  相似文献   
39.
Objective: Our purpose was to determine whether insulin-like growth factors I and II preferentially stimulate uterine leiomyoma cells versus myometrial cells in monolayer culture.Study design: Leiomyomas and normal myometrium were obtained at hysterectomy from five premenopausal women. Specimens were enzymatically digested for use in primary monolayer cell cultures. By use of serum-free media, insulin-like growth factor I or II was added in 1, 10, and 100 ng/ml concentrations to both cell types with the patient serving as her own control. Cell number, prolactin production, and proliferative index values were measured on day 15 of cell culture.Results: Significant increases in cell number were found in the leiomyoma cultures (p < 0.05) treated with 10 and 100 ng/ml insulin-like growth factors I but not with insulin-like growth factos II. Neither factor exerted a stimulatory effect on myometrial cells.Conclusion: Insulin-like growth factor sI preferentially stimulates leiomyoma cells in monolayer culture. These results suggest an autocrine-paracine role in vivo for this factor in conjuction with gonadal steroids in promoting leiomyoma growth.  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