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   24569篇
  免费   8286篇
  国内免费   163篇
耳鼻咽喉   223篇
儿科学   553篇
妇产科学   469篇
基础医学   4935篇
口腔科学   957篇
临床医学   3773篇
内科学   6129篇
皮肤病学   537篇
神经病学   1913篇
特种医学   1737篇
外科学   5864篇
综合类   278篇
一般理论   11篇
预防医学   2833篇
眼科学   417篇
药学   1262篇
  1篇
中国医学   11篇
肿瘤学   1115篇
  2021年   351篇
  2020年   260篇
  2018年   333篇
  2017年   365篇
  2016年   537篇
  2015年   861篇
  2014年   1464篇
  2013年   2092篇
  2012年   630篇
  2011年   534篇
  2010年   1153篇
  2009年   1256篇
  2008年   495篇
  2007年   297篇
  2006年   424篇
  2005年   348篇
  2004年   309篇
  2003年   259篇
  2002年   292篇
  2001年   440篇
  2000年   353篇
  1999年   559篇
  1998年   802篇
  1997年   765篇
  1996年   809篇
  1995年   773篇
  1994年   659篇
  1993年   609篇
  1992年   592篇
  1991年   566篇
  1990年   504篇
  1989年   596篇
  1988年   624篇
  1987年   606篇
  1986年   564篇
  1985年   598篇
  1984年   537篇
  1983年   524篇
  1982年   585篇
  1981年   548篇
  1980年   531篇
  1979年   508篇
  1978年   500篇
  1977年   504篇
  1976年   436篇
  1975年   393篇
  1974年   354篇
  1973年   333篇
  1972年   335篇
  1971年   304篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
81.
Summary.  Previously we demonstrated that domain 5 (D5) of high-molecular-weight kininogen (HK) inhibits neovascularization in the chicken chorioallantoic membrane (CAM) assay and further found that kallikrein cleaved HK (HKa) inhibited FGF2-and VEGF-induced neovascularization, and thus was antiangiogenic. In this study, we sought to demonstrate whether uncleaved HK stimulates neovascularization and thus is proangiogenic. The chick chorioallantoic membrane was used as an in ovo assay of angiogenesis. Low-molecular-weight kininogen stimulates angiogenesis, indicating that D5 is not involved. Bradykinin stimulates neovascularization equally to HK and LK and is likely to be responsible for the effect of HK. A murine monoclonal antibody to HK (C11C1) also recognizes a similar component in chicken plasma as detected by surface plasmon resonance. Angiogenesis induced by FGF2 and VEGF is inhibited by this monoclonal antibody and is a more potent inhibitor of neovascularization induced by VEGF than an integrin αvβ3 antibody (LM 609). Our postulate that C11C1 inhibits the stimulation of angiogenesis by HK was confirmed when either C11C1 or D5 completely inhibited angiogenesis in the CAM induced by HK. Growth of human fibrosarcoma (HT-1080) on the CAM was inhibited by GST-D5 and C11C1. These results indicate HK is proangiogenic probably by releasing bradykinin and that a monoclonal antibody directed to HK could serve as an antiangiogenic agent with a potential for inhibiting tumor angiogenesis and other angiogenesis-mediated disorders.  相似文献   
82.
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   
83.
84.
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   
85.
86.
87.
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   
88.
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   
89.
90.
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