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   1272783篇
  免费   97090篇
  国内免费   1607篇
耳鼻咽喉   16380篇
儿科学   41262篇
妇产科学   35147篇
基础医学   191058篇
口腔科学   34827篇
临床医学   118793篇
内科学   250127篇
皮肤病学   27531篇
神经病学   102859篇
特种医学   47271篇
外国民族医学   268篇
外科学   179898篇
综合类   25797篇
现状与发展   3篇
一般理论   569篇
预防医学   105463篇
眼科学   28182篇
药学   93222篇
  6篇
中国医学   2052篇
肿瘤学   70765篇
  2018年   13913篇
  2017年   10623篇
  2016年   11593篇
  2015年   13381篇
  2014年   18373篇
  2013年   27932篇
  2012年   38437篇
  2011年   40829篇
  2010年   23461篇
  2009年   22634篇
  2008年   38461篇
  2007年   41155篇
  2006年   40658篇
  2005年   39810篇
  2004年   38185篇
  2003年   36584篇
  2002年   35365篇
  2001年   56138篇
  2000年   57158篇
  1999年   48177篇
  1998年   13452篇
  1997年   12254篇
  1996年   12675篇
  1995年   11936篇
  1994年   11134篇
  1993年   10443篇
  1992年   38234篇
  1991年   37708篇
  1990年   36492篇
  1989年   35305篇
  1988年   32744篇
  1987年   32074篇
  1986年   30582篇
  1985年   28845篇
  1984年   21987篇
  1983年   19220篇
  1982年   11381篇
  1981年   10357篇
  1979年   20965篇
  1978年   15422篇
  1977年   12807篇
  1976年   11871篇
  1975年   12828篇
  1974年   15602篇
  1973年   15387篇
  1972年   14529篇
  1971年   13570篇
  1970年   12797篇
  1969年   12089篇
  1968年   11250篇
排序方式: 共有10000条查询结果,搜索用时 187 毫秒
941.
942.
A recent paper in this journal (1) suggests that involving terminally ill patients in choices concerned with Cardio-Pulmonary Resuscitation (CPR) produces 'psychological pain' and therefore is ill-advised. Such a claim rests on anecdotal observations made by the authors. In this paper I suggest that drawing conclusions in ethics, no less than in science, requires a rigorous framework and cannot be relegated to personal observation of a few cases. The paper concludes by suggesting that patients, if we acknowledge their valid interest in making their own choices, must themselves be allowed to make a prior choice about choosing. Those who may not wish to choose may properly be relieved of this burden and may allow another to choose for them. Routinely allowing others to make choices for competent adults, however, is likely to decrease communication with the dying patient and to introduce an atmosphere of suspicion and fear and to exclude the competent patient from his/her rightful place in the community.  相似文献   
943.
944.
945.
946.
Study of embryotoxic action of deoxynivalenol in levels of 0.2, 1, 5, 10 mg/kg from 7 to 15 day of rat pregnancy was worked up. The 0.2 mg/kg determined as a maximal acceptable dose without toxic effects.  相似文献   
947.
Chick nutritional encephalomalacia and prostanoid formation   总被引:2,自引:0,他引:2  
Nutritional encephalomalacia (NE) was induced in young chicks using a diet low in vitamin E and containing 8% ethyl esters derived from safflower oil fatty acids (S-E group). The same diet with added alpha-tocopheryl acetate (S+E) failed to produce the pathology, and chicks receiving aerated linseed oil--high in alpha-linolenic acid and low in alpha-tocopherol (L-E)--did not develop symptoms. Formation of metabolites from labeled arachidonic acid (AA) by thrombocytes was similar in the S+E and S-E groups, yielding thromboxane B2 (TXB2) and hydroxy fatty acids as the major products. Collagen-induced thrombocyte aggregation and TXB2 production were not significantly different in the S-E and S+E groups, but aggregation values and TXB2 synthesis were significantly less in the L-E group than in the ataxic S-E chicks. Prostaglandin E2 production by aortal rings was significantly influenced by the diet; S-E yielded the highest value and L-E the lowest. These results show that alpha-linolenic acid causes alterations in the AA metabolism and thrombocyte function in young chicks.  相似文献   
948.
We measured thiamin status in 137 incarcerated and 42 nonincarcerated adolescent males by use of both dietary intake data and a standard biochemical assay, thiamin pyrophosphate (TPP) response. Average thiamin intake of the total group was greater than 120% of the age-specific recommended dietary allowance (RDA). Ninety-two percent of incarcerated subjects and 93% of nonincarcerated subjects were consuming greater than or equal to 70% of RDA. Although average daily thiamin intake of nonincarcerated subjects was significantly higher than that of incarcerated subjects, both groups appeared to be at minimal risk for marginal thiamin status. Comparison of TPP response values indicated that there was no significant difference between groups. However, approximately 24% of the total population appeared to have less than adequate RBC thiamin on the basis of current standards for TPP response. Neither dietary intake nor reported previous alcohol intake was correlated with TPP response. These discrepant findings raise questions about the usefulness of the TPP response as the sole indicator of marginal thiamin status.  相似文献   
949.
Reference data for obesity   总被引:1,自引:0,他引:1  
  相似文献   
950.
Resting energy expenditure (REE) was measured in 68 patients with stable chronic obstructive pulmonary disease (COPD) and in 34 weight-stable, age-matched (65 +/- 8 y; means +/- SD) healthy control subjects. Fat-free mass (FFM) determined by bioelectrical resistance explained 84% of the variation in REE in the control group but only 34% in the COPD patients. REE could not reliably be predicted from regression equations either developed in healthy subjects or in COPD patients. REE adjusted for FFM was significantly higher (P less than 0.05) in weight-losing (n = 34) than in weight-stable (n = 34) patients (6851 +/- 781 and 6495 +/- 650 kJ/d, respectively). Pulmonary function was more compromised in weight-losing patients. Adjusted REE in weight-stable patients was significantly higher (P less than 0.01) than in the healthy control group (6131 +/- 405 kJ/d). In patients with COPD, factors in addition to FFM are important determinants of REE. A disease-related increase in REE develops, which may contribute to weight loss in COPD in combination with a lack of an adaptive response to undernutrition in weight-losing patients.  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