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   1768篇
  免费   139篇
  国内免费   1篇
耳鼻咽喉   24篇
儿科学   64篇
妇产科学   23篇
基础医学   190篇
口腔科学   59篇
临床医学   214篇
内科学   281篇
皮肤病学   19篇
神经病学   151篇
特种医学   111篇
外科学   235篇
综合类   28篇
一般理论   3篇
预防医学   130篇
眼科学   10篇
药学   202篇
中国医学   6篇
肿瘤学   158篇
  2021年   29篇
  2019年   26篇
  2018年   19篇
  2017年   14篇
  2016年   13篇
  2015年   24篇
  2014年   30篇
  2013年   47篇
  2012年   70篇
  2011年   69篇
  2010年   19篇
  2009年   34篇
  2008年   41篇
  2007年   54篇
  2006年   55篇
  2005年   45篇
  2004年   63篇
  2003年   67篇
  2002年   60篇
  2001年   74篇
  2000年   74篇
  1999年   53篇
  1998年   23篇
  1997年   14篇
  1996年   14篇
  1995年   16篇
  1994年   18篇
  1993年   31篇
  1992年   63篇
  1991年   62篇
  1990年   69篇
  1989年   40篇
  1988年   36篇
  1987年   59篇
  1986年   58篇
  1985年   43篇
  1984年   42篇
  1983年   26篇
  1982年   23篇
  1981年   22篇
  1980年   26篇
  1979年   38篇
  1978年   27篇
  1977年   15篇
  1976年   16篇
  1975年   13篇
  1974年   14篇
  1972年   15篇
  1970年   19篇
  1969年   14篇
排序方式: 共有1908条查询结果,搜索用时 15 毫秒
1.
2.
Aim : The study was designed to determine the effect of computerized nutrition information on consumer food choice in two workplace restaurants, one in which customers had to pay for their lunch and the other providing a free lunch. Methods : Customers entering the restaurants were asked to make selections from the menu on a computer screen. The energy, saturated fatty acids, non-milk extrinsic sugars and non-starch polysaccharide content of the meal selected was displayed graphically in proportion to the dietary reference values. They were given the opportunity to change their selected meal and the composition of all meals was recorded. Results : The nutritional composition of the first meal provoked 16% of customers to make a second selection. The proportion of energy in the first selection had been 31% higher for saturated fatty acids and 23% higher for non-milk extrinsic sugars than the first selection made by people who were satisfied with their first choice. In their second attempt they succeeded in reducing both nutrients to levels similar to those present in the meals selected by people who had been satisfied with their first selection. Customers>> selections for non-starch polysaccharide and energy did not differ between the groups. The main changes made by customers to achieve improved second choices were to omit dishes (44%), add dishes (19%), make changes within a menu category (46%), and make changes from one menu category to another (26%). Conclusion : It was concluded that provision of graphical nutrition information on a computer screen could be used by a subset of the users of both restaurants to enable them to improve their menu selections to a similar composition to that selected by the other people who used the computer system.  相似文献   
3.
Dermal absorption of the insecticide lindane was determined following topical application of ring 14C-labeled lindane to the tail of Sprague-Dawley rats. The tail was tested as a practical alternative to the rat mid-dorsal (back) region, and the data obtained were compared to those with rat back and with those of rhesus monkeys in our previous reports. There was no significant difference between total percentage urinary 14C recovery for rats dosed on the tail with occlusive tail covers (52 +/- 6.2%; t1/2 = 2.7 d) compared to those with nonocclusive covers (55 +/- 4.4%; t1/2 = 2.9 d). Neither the total percentage urinary recovery nor the t1/2 values obtained for the rat tail and rat back models differed significantly. Carbon-14 activity was still detectable in urine samples taken after 72 d post-treatment. However, an extensive tissue analysis failed to demonstrate 14C activity persisting at 72 d, with the exception of trace levels detected in blood serum and tail tissue. Advantages of the rat tail model are highlighted.  相似文献   
4.
5.
This study compares the heart sizes and left ventricular masses of soldiers (n = 11) with age- and body size-matched groups of sedentary men (n = 10) and accomplished athletes (n = 11). Echocardiography revealed that active duty soldiers (A) who met minimal fitness standards and pentathletes (P) had greater average left ventricular (LV) end-diastolic volumes (A = 10%, NS; P = 28%, p less than 0.05), stroke volumes (A = 29%, NS; P = 44%, p less than 0.01), and LV masses (A = 22%, NS; P = 76%, p less than 0.01) than sedentary subjects. Athletes had an average LV wall thickness which was 23% (p less than 0.05) greater than that of soldiers and 32% (p less than 0.01) greater than that of sedentary men. The LV wall thickness to radius ratio (h/r) was similar between soldiers and sedentary men, but in athletes the h/r was greater (p less than 0.01) than in the less conditioned subjects. These data suggest that soldiers who meet minimal standards of fitness exhibit cardiac morphometric features consistent with endurance conditioning. However, the soldiers studied were significantly less (p less than 0.001) conditioned than the competitive athletes. These data suggest that improvements in aerobic and cardiac conditioning could be achieved through a greater emphasis on physical training.  相似文献   
6.
7.
A total of 277 third and fourth year medical students and 304 house officers and senior house officers were asked to prioritise the content and methods of clinical teaching. Response rates were poor, but similar to that in market surveys. Bedside teaching and medical clerking were considered the most valuable methods of teaching and training in practical procedures such as venepunctures and urinary catheterisation was seen as valuable. The design of new curricula in medical education will need to accommodate the views of its clients.  相似文献   
8.
9.
10.
The pharmacokinetics and effect of single oral doses of carbamazepine (400 mg) were compared in a group of six young volunteers aged between 20 and 25 years, and a second group of five elderly volunteers aged between 66 and 84 years. No age related changes in salivary or plasma pharmacokinetics or in psychomotor function were detected.  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