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   724篇
  免费   81篇
  国内免费   1篇
耳鼻咽喉   7篇
儿科学   7篇
妇产科学   15篇
基础医学   100篇
口腔科学   6篇
临床医学   135篇
内科学   145篇
皮肤病学   8篇
神经病学   35篇
特种医学   37篇
外科学   93篇
综合类   10篇
预防医学   75篇
眼科学   11篇
药学   90篇
中国医学   1篇
肿瘤学   31篇
  2021年   12篇
  2019年   16篇
  2018年   16篇
  2017年   11篇
  2016年   8篇
  2015年   11篇
  2014年   11篇
  2013年   21篇
  2012年   23篇
  2011年   26篇
  2010年   21篇
  2009年   15篇
  2008年   29篇
  2007年   29篇
  2006年   33篇
  2005年   25篇
  2004年   13篇
  2003年   19篇
  2002年   19篇
  2001年   16篇
  2000年   25篇
  1999年   20篇
  1998年   8篇
  1997年   9篇
  1996年   5篇
  1995年   9篇
  1994年   8篇
  1993年   7篇
  1992年   29篇
  1991年   18篇
  1990年   20篇
  1989年   21篇
  1988年   23篇
  1987年   16篇
  1986年   16篇
  1985年   26篇
  1984年   17篇
  1983年   18篇
  1982年   12篇
  1981年   10篇
  1980年   7篇
  1979年   17篇
  1978年   8篇
  1977年   9篇
  1976年   8篇
  1974年   9篇
  1973年   6篇
  1972年   7篇
  1971年   10篇
  1970年   7篇
排序方式: 共有806条查询结果,搜索用时 15 毫秒
1.
2.
Recently, public and private efforts have been mounted to promote screening mammography. To assess recent trends in the percentage of women 50 years of age and older who have had a screening mammogram, we analyzed data from interviews from women from 33 states who participated in the 1987 Behavioral Risk Factor Surveillance System. Our study group included 8,402 women 50 years of age and older who had visited a physician for a routine checkup in the last year; among these 8,402 women, only 29% reported having had a screening mammogram in the past year. However, of the women in the study group, the percentage who had a screening mammogram in the last year showed a relative increase of 38% during 1987, from 24% for women interviewed in the first quarter of 1987 to 33% for women interviewed in the fourth quarter. However, not all groups of patients benefited equally from the observed trend--the absolute and relative increases in the percentage of women screened were lowest for women who were older, less educated, in low-income groups, and who had poor personal health practices. Although the percentage of women 50 years of age and older who reported being screened increased dramatically during 1987, special efforts are needed to reach the patient groups that are being left behind in the trend toward increased use of screening mammograms.  相似文献   
3.
Transforming growth factors-beta (TFG beta s) are multifunctional peptides that affect proliferation, differentiation, and many other functions in a variety of cell types. In this study we examined the effect of TGF beta 1 on aldosterone and adrenal renin production using cultured bovine adrenal zona glomerulosa cells. Collagenase-dispersed zona glomerulosa cells were incubated in PFMR-4 medium containing 10% fetal calf serum for 72 h, and the medium was replaced with serum-free medium for the next 24 h. The cells during this 24-h period were exposed to TGF beta 1, ACTH, and (Bu)2cAMP (dbcAMP). It was observed that TGF beta 1 at 1 nM 1) inhibited basal aldosterone secretion from 680.0 +/- 40.0 to 270.0 +/- 10.0 pg/10(6) cells.h, 2) inhibited ACTH- and dbcAMP-stimulated aldosterone production, 3) increased levels of active renin in the cells from 17.8 +/- 2.5 to 70.7 +/- 4.4 pg angiotensin-I/10(6) cells.h and prorenin from 270.0 +/- 5.0 to 970.0 +/- 90 pg angiotensin-I/10(6) cells.h, 4) stimulated prorenin in the medium synergistically in combination with ACTH and dbcAMP, and 5) had no significant effect on basal cAMP production, but significantly inhibited the ACTH-stimulated production of cAMP. These observations show that TGF beta 1 is a potent inhibitor of basal and ACTH- and cAMP-stimulated aldosterone production and inhibits ACTH-stimulated cAMP production. Contrary to its effect on aldosterone, TGF beta 1 stimulates the synthesis and release of adrenal renin and prorenin. TGF beta 1 may act as an autocrine or paracrine regulator of aldosterone production.  相似文献   
4.
5.
A deceased donor (DD) allocation system incorporating net life survival benefit has been proposed. In this system, many kidneys will be shifted to younger recipients, thereby decreasing their waiting times. The goal of this study was to determine the potential effects of altering waiting times on the likelihood of live donor kidney transplantation (LDKT). We analyzed 93,727 waiting list candidates to determine the association of various patient factors with likelihood of LDKT. The proportion of patients receiving LDKT was compared by the median DD waiting time at that patient's transplant center for someone of that patient's age category and race. LDKT was consistently higher as waiting times became longer. After adjusting for all other factors associated with likelihood of LDKT, waiting time remained a significant, independent predictor. Patients with the longest DD waiting times had 2.3-fold higher odds of LDKT (95% CI 2.11-2.58, p < 0.001). In planning the new DD allocation policy, we must account for resulting alterations in LDKT. It is possible that shifting DD kidneys to younger recipients may decrease LDKT or shift it to older recipients, net effects not consistent with the goal of net life survival benefit.  相似文献   
6.
7.
Facial trauma and associated brain damage   总被引:2,自引:0,他引:2  
CT continues to be the most important diagnostic study for detection and classification of maxillofacial injury. MR has a complementary role in specific situations because of its multiplanar imaging capabilities and exquisite soft tissue contrast resolution. MR is particularly useful for evaluation of orbital "blow-out" fractures, intraorbital and intraocular hemorrhage, traumatic vascular injuries, and associated intracranial damage.  相似文献   
8.
A set of calibrated lickometers provides continuous, quantitative monitoring of fluid consumption. It has been used in our laboratory at four levels of temporal resolution: 24 hr, 1 hr, 6 min, and for counting of individual licks. Convenient features are mounting of the licking tube-bottle assembly on the cage top (which permits the use of disposable plastic cages with litter) and automated collection of data with microcomputers.  相似文献   
9.
10.
Summary Forty-two hybridomas secreting IgM antibody against dengue virus were derived from spleen cells of dengue 2 infected mice. Antibody from 27 of these recognised the E protein of this virus. Of the 22 antibodies which neutralised dengue 2, only two cross-reacted with other flaviviruses. These 22 antibodies recognised three discrete domains on dengue virions. Competitive binding studies with IgG monoclonal antibodies suggested that two of the three domains were recognised by both IgG and IgM antibodies and that there were two additional domains which may be recognised exclusively by either IgG or IgM antibodies. IgM antibodies reacting with domains recognised by IgG antibodies that enhanced infection of susceptible cells by dengue 2, had no enhancing properties. None of the IgM antibodies activated the serum complement system after reacting with dengue 2 virions.  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