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   17975篇
  免费   600篇
  国内免费   543篇
耳鼻咽喉   78篇
儿科学   248篇
妇产科学   334篇
基础医学   1505篇
口腔科学   475篇
临床医学   1178篇
内科学   1919篇
皮肤病学   439篇
神经病学   1160篇
特种医学   353篇
外国民族医学   1篇
外科学   1028篇
综合类   1224篇
预防医学   1706篇
眼科学   641篇
药学   3600篇
  2篇
中国医学   2022篇
肿瘤学   1205篇
  2024年   62篇
  2023年   868篇
  2022年   706篇
  2021年   1070篇
  2020年   1213篇
  2019年   1255篇
  2018年   1266篇
  2017年   962篇
  2016年   765篇
  2015年   688篇
  2014年   1406篇
  2013年   2406篇
  2012年   846篇
  2011年   651篇
  2010年   524篇
  2009年   430篇
  2008年   388篇
  2007年   473篇
  2006年   369篇
  2005年   308篇
  2004年   293篇
  2003年   226篇
  2002年   190篇
  2001年   190篇
  2000年   156篇
  1999年   144篇
  1998年   115篇
  1997年   106篇
  1996年   108篇
  1995年   84篇
  1994年   104篇
  1993年   76篇
  1992年   61篇
  1991年   44篇
  1990年   58篇
  1989年   52篇
  1988年   47篇
  1987年   35篇
  1986年   34篇
  1985年   63篇
  1984年   55篇
  1983年   51篇
  1982年   39篇
  1981年   29篇
  1980年   23篇
  1979年   18篇
  1978年   16篇
  1977年   10篇
  1976年   13篇
  1975年   11篇
排序方式: 共有10000条查询结果,搜索用时 453 毫秒
61.
便携式野战真空注油设备的研制   总被引:1,自引:0,他引:1  
本文将介绍在野战条件下,便携式真空注油设备,可以方便的更换X-线机球管及给变压器注油。并阐述了该设备的结构及原理。  相似文献   
62.
橄榄油对单核吞噬细胞系统的影响   总被引:1,自引:0,他引:1  
本文采用橄榄油皮下注射、观察其对小鼠腹腔单核吞噬细胞的游出、活化及吞噬功能。结果发现、橄榄油对上述功能均有明显的抑制作。  相似文献   
63.
明党参鲜根与药材饮片中精油成分和氨基酸含量比较   总被引:4,自引:1,他引:3  
对明党参鲜根和饮片中的精油及氨基酸成分进行了比较分析,鉴定出27种精油成分,并发现炮制前后氨基酸成分含量变化较大。  相似文献   
64.
灰星鲨肝油中甘油酯类与烃类的高效液相色谱分离   总被引:1,自引:1,他引:0  
采用高效液相色谱法,有效地分离鲨鱼肝油中的两类主要成份甘油酯和烃类。  相似文献   
65.
This is the first round in a series of surveys conducted inFort McMurray as part of the Fort McMurray Demonstration Projectin social marketing. This component of the survey was intendedto focus on the most prominent group of employed workers inthe community and to compare their patterns of response withthe community as a whole. Respondents to the survey were overwhelminglymale (96%), married (72.9%) and living in households of twoto five persons (87.9%). They were predominantly aged 30–44(55%) and graduates of high school (53.5%). Younger male workers(below age 30) were more likely to have a high school diploma(78.3%) or some additional technical or vocational training(21.7% compared to 12.5% overall) and to be unmarried or separated.Attitudes toward safety-related behaviours were stronger thanfor respondents from the community as a whole. Approximately70–100% of all age groups and both sexes showed strongagreement with attitudes involving child car seats and the unacceptabilityof drinking and driving. These attitudes include strong advocacyof vigorous enforcement of occupational health and safety standards.However, they showed a variability similar to the communityas a whole in behaviour at home compared to work, generallyreporting more consistent use of personal protection on thejob than in their own homes, particularly hearing protection.Even so, they were much less likely to perform stretching andwarm-up exercises prior to exertion than community residentsin general. The potential may exist to transfer the technologyand attitudes from workplace health and safety to communitysafety. One possible strategy to accomplish this is to involveworkers in this industry directly in community initiatives.This strategy may be generalizable to any community in whichthere are major employers who place a heavy emphasis on riskcontrol and occupational health and safety.  相似文献   
66.
Summary To evaluate the influence of the stomach and the cholinergic system on gallbladder contraction induced by physiological stimuli, the reduction in gallbladder volume in 7 healthy volunteers has been studied by real-time ultrasonography after the oral and intraduodenal administration of olive oil, preceded by pretreatment with cimetropium bromide or placebo. After an overnight fast, each subject swallowed 50 ml olive oil or it was administered through a naso-duodenal tube in the proximal duodenum. Cimetropium bromide 5 mg or placebo was given intravenously under double-blind control.After the placebo pretreatment, gallbladder contraction was greater and faster after intraduodenal oil than after oral oil. Cimetropium bromide decreased the extent, velocity and duration of gallbladder contraction induced by intraduodenal olive oil but it only reduced the velocity of the contraction induced by oil given orally.It is concluded that in normal human subjects the stomach modulates the extent and velocity of postprandial gallbladder contraction and that anticholinergic agents antagonize the gastric and duodenal phases of the response of the gallbladder to a meal.  相似文献   
67.
采用Ames试验、E Coli大肠杆菌突变试验和动物骨髓细胞微核试验对油页岩及其矿渣提取物进行了致突变性鉴定。结果表明油页岩及其矿渣提取物在微核试验中呈阳性反应,而在细菌回变试验中呈阴性反应。  相似文献   
68.
1. The effects of graded doses of the α2-adrenoceptor agonists clonidine, tizanidine and BHT-920, and the α2-adrenoceptor antagonists yohimbine and idazoxan, on gastrointestinal transit were investigated in mice using the charcoal meal test. 2. The agonists produced significant and dose-dependent decreases in gastrointestinal transit, and the antagonists produced the opposite effect. In affecting the gastrointestinal transit, clonidine (1 mg/kg) was as effective as tizanidine (12 mg/kg) and BHT-920 (40 mg/kg), while yohimbine (2 mg/kg) was as effective as idazoxan (1 mg/kg). 3. Morphine (2, 4 and 8 mg/kg) significantly inhibited gastrointestinal transit. This effect was significantly reversed by the co-administration of yohimbine (2 mg/kg) and idazoxan (1 mg/kg). 4. The acute administration of glucose (5.04 g/kg, i.p.) potentiated the inhibition of gastrointestinal transit produced by clonidine (1 mg/kg) and BHT-920 (40 mg/kg). Glucose treatment, however, had no significant effect on the increase in gastrointestinal transit induced by yohimbine (2 mg/kg) or idazoxan (1 mg/kg). 5. Castor oil (0.25 mL/mouse, orally) induced diarrhoea in saline-treated animals within about 45 min. Clonidine (1 mg/kg), tizanidine (12 mg/kg) and BHT-920 (40 mg/kg) delayed the occurrence of diarrhoea to 2.1, 1.2 and 1.4 h, respectively.  相似文献   
69.
烹调油烟对机体健康的危害   总被引:17,自引:0,他引:17  
王献仁 《卫生研究》1994,23(5):274-277
烹调油烟气含有200多种有害气体。实验研究和流行病学调查表明:油烟气可损伤肺部功能,引起机体免疫功能下降,并具有致突变性和致癌性,是肿瘤发生的可疑因素。  相似文献   
70.
天津市煎炸油卫生状况评价   总被引:2,自引:0,他引:2  
通过连续8小时的煎炸实验和对市,郊29个煎炸点的现场卫生学调查及采用羰基值(COV),极性组分(PC)对所采样品的分析表明,天津煎炸油的总体的卫生质量基本符合国家卫生标准,参考极性组分的ADI值并依据本次调查结果,估计天津大部分居民的煎炸食品摄入量安全水平,但对于偏爱煎炸食品者其安全系数明显下降。  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