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   1696934篇
  免费   123804篇
  国内免费   3795篇
耳鼻咽喉   21735篇
儿科学   55679篇
妇产科学   46171篇
基础医学   241416篇
口腔科学   48797篇
临床医学   151398篇
内科学   333954篇
皮肤病学   38751篇
神经病学   131325篇
特种医学   63928篇
外国民族医学   242篇
外科学   257433篇
综合类   38950篇
现状与发展   4篇
一般理论   531篇
预防医学   124244篇
眼科学   40235篇
药学   123751篇
  7篇
中国医学   4479篇
肿瘤学   101503篇
  2021年   12813篇
  2019年   13551篇
  2018年   19977篇
  2017年   15234篇
  2016年   16643篇
  2015年   18988篇
  2014年   26244篇
  2013年   37993篇
  2012年   52815篇
  2011年   55528篇
  2010年   32830篇
  2009年   30748篇
  2008年   51609篇
  2007年   54906篇
  2006年   55337篇
  2005年   52621篇
  2004年   50810篇
  2003年   48224篇
  2002年   46446篇
  2001年   91843篇
  2000年   93652篇
  1999年   77006篇
  1998年   19736篇
  1997年   17284篇
  1996年   17409篇
  1995年   16760篇
  1994年   15306篇
  1993年   14090篇
  1992年   57417篇
  1991年   55322篇
  1990年   53000篇
  1989年   50779篇
  1988年   46149篇
  1987年   44964篇
  1986年   42254篇
  1985年   40005篇
  1984年   29367篇
  1983年   24920篇
  1982年   13904篇
  1979年   25542篇
  1978年   17582篇
  1977年   14910篇
  1976年   13880篇
  1975年   14570篇
  1974年   17636篇
  1973年   16945篇
  1972年   15674篇
  1971年   14455篇
  1970年   13433篇
  1969年   12519篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
992.
993.
This study evaluates the glycine potentiation of anticonvulsant drugs in subcutaneous pentylenetetrazol seizures in rats. Administered alone, glycine (30 or 40 mM/kg, PO) induced no anticonvulsant effect or neurological deficit. Coadministered with anticonvulsants, glycine significantly enhanced the anticonvulsant potency of diazepam and sodium valproate without affecting the neurological deficit induced by the anticonvulsants. Glycine did not significantly alter the anticonvulsant activity of ethosuximide or phenobarbital. These findings indicate a possible glycine-sensitive component in the mechanism of action of diazepam and sodium divalproate in subcutaneous pentylenetetrazol seizures. With the possible exception of sodium valproate, the present study provides little support for a glycine and gamma-aminobutyric acid (GABA) interaction as a mechanism of anticonvulsant activity in SC PTZ seizures. Further studies are required to determine the role of strychnine-sensitive and strychnine-insensitive glycine receptors in this experimental model of absence epilepsy.  相似文献   
994.
The effect of ferritins from horse (FH) and bovine (FB) spleen and murine liver (FM) on the survival rate of CFW mice lethally infected with Escherichia coli (strain 8440-78 K 80/B) was evaluated. Ferritins given intravenously 24 h before intravenous inoculation of bacteria, protected mice most effectively from death due to infection. The effect was dose dependent. At 500 micrograms of ferritin per mouse, the maximum survival rates were 86% (FH), 81% (FM) and 79% (FB), while only 5% of the control mice survived up to the 30th day. The survival rates of animals injected with bovine serum albumin (BSA) and heat-inactivated FB were 8 and 25%, respectively. Intraperitoneal injection of FB was as effective as intravenous in enhancing the resistance of mice against bacteria. These data provide evidence for the beneficial role of tissue ferritins in nonspecific antibacterial resistance.  相似文献   
995.
Benzene is metabolized to one or more hematotoxic species. Saturation of benzene metabolism could limit the production of toxic species. Saturation of phase II enzymes involved in the conjugation of the phenolic metabolites of benzene also could affect the hematotoxicity of benzene. To investigate the latter possibility, we exposed male Swiss mice, via the inhalation route, to various concentrations of benzene for 6 h per day for 5 days. Following termination of the final exposure the mice were killed and the levels of phenylsulfate and phenylglucuronide in the blood determined. Spleen weights were recorded and the number of white blood cells counted. At low benzene exposure concentrations phenylsulfate is the major conjugated form of phenol in the blood. At high exposure concentrations, phenylglucuronide is the predominant species. The reductions in spleen weight and white blood cell numbers correlated with the concentration of phenylsulfate in the blood, but are most probably not causally related.  相似文献   
996.
The aim of this study was to evaluate the public opinion towards the possible replacement of ration cards by cash payment and to investigate the effect of partial termination of food price subsidy programme on food consumption by families from different income brackets. A purposive sample of 300 families from Alexandria Governorates were interviewed to assess the attitude of the consumer towards the possible termination of current food subsidy programme. After one year, during which the subsidy programme was reduced, a follow up sample of 240 were interviewed. The results show that a large proportion of the families prefer the continuation of the current programme (80-81.2%), meanwhile, around 90% of them believed that subsidized foods do not reach the target group. The data show that subsidized meat and poultry are consumed by high income families while frozen subsidized fish was mostly consumed by poor families. The partial termination of the subsidy programme forced the families to reduce their consumption from sugar, tea, oil, and rice. During the second phase of the study. However the results show that high income families were least affected by the partial termination of the subsidy programme.  相似文献   
997.
998.
S L Lee 《JAMA》1991,266(2):217-218
  相似文献   
999.
A tax reform strategy to deal with the uninsured   总被引:1,自引:0,他引:1  
S M Butler 《JAMA》1991,265(19):2541-2544
The high level of ininsurance in the United States is due in large measure to the tax treatment of health care, which is based on the tax exclusion for company-provided plans. Correcting the perverse incentives for providers and patients resulting from this tax treatment is the crucial step to creating a national health care system that is affordable and efficient. The Heritage Foundation proposal calls for the elimination of the current tax exclusion and its replacement with a system of refundable tax credits for the purchase of health insurance and medical services.  相似文献   
1000.
An empirical investigation of the perceived role of robotics and artificial computer intelligence in the future of health care reveals factors favoring a positive attitude by health administrators. The study employed a two-part survey administered in late 1989 and early 1990 to health care managers in hospitals and nursing homes. Part One of the survey asked about the participant, his or her work habits and work environment. Part Two obtained a psychological profile of rationality vs. intuition in problem solving. Through bivariate and multivariate post hoc statistical tests, we discovered the following variables which significantly determined attitudes toward robotics and artificial computer intelligence: sex, number of employees supervised; perceptions of waste and inefficiency in the workplace; perceptions of time-consuming personnel problem; perceived need to make more efficient use of time, money, and facilities; and perceived favorable climate for innovation. Among the factors which did not have an effect on attitudes toward advanced technology were three measures of rationality vs. intuition in problem solving.  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