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   3143篇
  免费   283篇
  国内免费   9篇
耳鼻咽喉   33篇
儿科学   118篇
妇产科学   121篇
基础医学   415篇
口腔科学   43篇
临床医学   338篇
内科学   515篇
皮肤病学   36篇
神经病学   173篇
特种医学   167篇
外科学   513篇
综合类   104篇
一般理论   15篇
预防医学   257篇
眼科学   17篇
药学   270篇
  1篇
中国医学   20篇
肿瘤学   279篇
  2022年   22篇
  2021年   50篇
  2020年   34篇
  2019年   52篇
  2018年   66篇
  2017年   49篇
  2016年   52篇
  2015年   85篇
  2014年   90篇
  2013年   131篇
  2012年   166篇
  2011年   151篇
  2010年   119篇
  2009年   99篇
  2008年   129篇
  2007年   138篇
  2006年   107篇
  2005年   114篇
  2004年   111篇
  2003年   97篇
  2002年   85篇
  2001年   68篇
  2000年   83篇
  1999年   68篇
  1998年   54篇
  1997年   52篇
  1996年   58篇
  1995年   54篇
  1994年   37篇
  1993年   37篇
  1992年   59篇
  1991年   48篇
  1990年   44篇
  1989年   55篇
  1988年   76篇
  1987年   65篇
  1986年   49篇
  1985年   47篇
  1984年   40篇
  1983年   24篇
  1982年   33篇
  1981年   24篇
  1979年   30篇
  1978年   19篇
  1977年   19篇
  1976年   25篇
  1975年   24篇
  1974年   21篇
  1973年   20篇
  1972年   22篇
排序方式: 共有3435条查询结果,搜索用时 31 毫秒
1.
2.
CONTEXT: The physician assistant profession has been moving toward requiring master's degrees for new practitioners, but some argue this could change the face of the discipline. PURPOSE: To see if there is an association between physician assistants' academic degrees and practice in primary care, in rural areas, and with the medically underserved. METHODS: Surveys were sent to 880 graduates of the first 32 University of Washington physician assistant classes through 2000. Respondents noted their academic degree at program entry and the highest degree attained at any time up to the time of survey. Relationships between practice characteristics and academic degree levels were tested by unadjusted odds ratios and logistic regression after controlling for year of graduation and sex. RESULTS: Of the 478 respondents, 54% worked in primary care, about 30% practiced in nonmetropolitan communities, and 42% reported providing care for the medically underserved. Respondents with no degree (33% of total at entry, 24% at survey) were significantly more likely than degree holders to work in primary care and nonmetropolitan areas. Respondents with no degree at program entry were significantly more likely, and those with no degree at the time of the survey were marginally more likely, to self-report work with the medically underserved. CONCLUSION: Respondents with no academic degree are significantly more likely to demonstrate a commitment to primary, rural, and underserved health care. These findings may inform the national debate about the impact of required advanced degrees on the practice patterns of nonphysician providers.  相似文献   
3.
AMPK在妊娠期糖尿病发病机制中的作用   总被引:1,自引:0,他引:1  
腺苷酸活化蛋白激酶是一种重要的蛋白激酶,主要作用是协调代谢和能量平衡.腺苷酸活化蛋白激酶被激活后,在增加骨骼肌对葡萄糖摄取、增强胰岛素敏感性、增加脂肪酸氧化以及调节基因转录等方面发挥重要作用.已经证实脂联素有调节糖脂代谢的作用,但其作用机制尚不十分清楚,很可能是通过腺苷酸活化蛋白激酶介导,对脂联素信号转导通路的研究将成为进一步理解脂联素作用的关键所在.而脂联素又是妊娠期糖尿病的预测因子,所以腺苷酸活化蛋白激酶逐渐成为对妊娠期糖尿病研究中的焦点.  相似文献   
4.
In conclusion, endopyelotomy has been developed over the past several decades on the basis of sound laboratory and clinical research. The success rates have been similar to those of the standard open pyeloplasty, and the procedure is not associated with undue complications. Endopyelotomy has several distinct advantages over open surgery, including the decreased morbidity and associated expense of an open operation, minimal interference with the blood supply of the ureter, and avoidance of removal of the ureter from its natural sheath, preventing the tendency to adhere to adjacent structures and thus kink. As the instrumentation available for percutaneous renal surgery has improved and been miniaturized, the techniques developed in adults have been progressively applied to younger and smaller children. There seems to be little doubt that a comparison of morbidity and socioeconomic factors associated with a successful endopyelotomy versus an open pyeloplasty in adults heavily favors the percutaneous procedures, and judicious application to children would seem warranted. However, the changing presentation of ureteropelvic junction obstruction in children that has resulted from the widespread use of prenatal ultrasonography may make the question moot. Open infant pyeloplasty is a highly successful procedure, accompanied by minimal morbidity and accomplished in a 2- to 3-day hospital stay. The socioeconomic factors are obviated in the infant, who already requires constant maternal care. However, endopyelotomy deserves consideration in the older child, especially if the obstruction is secondary in nature after a previous open procedure.  相似文献   
5.
6.
Research on children's early writing development in the past has focused primarily on product and process. In reviewing the more recent research on early writing development, however, a new focus of context emerges. Occurrences of literacy are now being observed in the home, the school, and the community. With this new emphasis, comes the task of defining context. A definition of context reflects theoretical perspectives, areas of research interests, and types of methodologies employed in conducting research. Therefore, the purpose of this article is to address the following aspects of context: #op1#cp multidiscipline perspectives and definitions of context, #op2#cp contextual shifts observed between the home and the school, #op3#cp contextual factors present when learning how to write, and #op4#cp pedagogical implications for curriculum development.  相似文献   
7.
8.
Furan is a liver carcinogen and toxicant. Furan is oxidized to the reactive dialdehyde, cis-2-butene-1,4-dial, by microsomal enzymes. This reactive metabolite readily reacts with glutathione nonenzymatically to form conjugates. A high-performance liquid chromatography-electrochemical method for the detection of cis-2-butene-1,4-dial-glutathione (GSH) conjugates in microsomal preparations was developed to measure the extent of furan metabolism to cis-2-butene-1,4-dial in vitro. Previously unobserved mono-GSH reaction products of cis-2-butene-1,4-dial were detected in addition to the already characterized bis-GSH conjugates. Chemical characterization of these compounds indicated that the alpha-amino group of glutathione had reacted with cis-2-butene-1,4-dial to form a thiol-substituted pyrrole adduct. The analytical method was used to estimate the extent of furan oxidation in rat liver microsomes from untreated or acetone-pretreated F344 rats as well as in human P450 2E1 Supersomes. Our results confirm that cytochrome P450 2E1 can catalyze the oxidation of furan to cis-2-butene-1,4-dial. However, the data are also consistent with the involvement of other P450 enzymes in the oxidation of furan in untreated animals. This assay will be a valuable tool to explore tissue and species differences in rates of furan oxidation.  相似文献   
9.
This paper describes experience in a modern district general hospital with a small desktop system for computer-aided diagnosis of acute abdominal pain, over a 12-year period involving 5512 cases. When compared with a baseline year (1973) in which unaided performance was monitored, during an initial study period (1974-76) the diagnostic accuracy of junior staff rose by between 10 and 15%. This higher performance level was then maintained for a decade (1976-86) despite changes in staff. The perforation rate among appendicitis cases fell from 27% to 12.5%, accompanied by a smaller fall in negative laparotomy rates. The saving in surgical bednights devoted to acute abdominal pain was approximately 15%, and the notional cost of resources saved during the first 6 years of operation was 120,000 pounds. Other hospitals have shown--in the short term--benefits similar to those obtained at Airedale District General Hospital. The long-term benefits of the system at Airedale reinforce the conclusions of the earlier short-term trials that a comparable system should probably be offered to all DGHs in the UK, not as an exercise in 'artificial intelligence' but as an effective continuing stimulus to good clinical practice.  相似文献   
10.
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