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   10947篇
  免费   970篇
  国内免费   17篇
耳鼻咽喉   80篇
儿科学   281篇
妇产科学   289篇
基础医学   1577篇
口腔科学   270篇
临床医学   1249篇
内科学   2554篇
皮肤病学   86篇
神经病学   812篇
特种医学   524篇
外科学   1281篇
综合类   189篇
一般理论   6篇
预防医学   1304篇
眼科学   109篇
药学   747篇
  1篇
中国医学   10篇
肿瘤学   565篇
  2021年   145篇
  2020年   92篇
  2019年   143篇
  2018年   165篇
  2017年   104篇
  2016年   152篇
  2015年   151篇
  2014年   266篇
  2013年   335篇
  2012年   461篇
  2011年   530篇
  2010年   313篇
  2009年   260篇
  2008年   514篇
  2007年   467篇
  2006年   467篇
  2005年   436篇
  2004年   369篇
  2003年   360篇
  2002年   344篇
  2001年   333篇
  2000年   325篇
  1999年   299篇
  1998年   149篇
  1997年   125篇
  1996年   154篇
  1995年   127篇
  1994年   108篇
  1993年   91篇
  1992年   271篇
  1991年   257篇
  1990年   246篇
  1989年   242篇
  1988年   242篇
  1987年   205篇
  1986年   232篇
  1985年   207篇
  1984年   196篇
  1983年   182篇
  1982年   125篇
  1981年   108篇
  1980年   92篇
  1979年   160篇
  1978年   122篇
  1977年   112篇
  1976年   92篇
  1974年   110篇
  1973年   107篇
  1972年   87篇
  1968年   88篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
22.
Preventive care: do we practice what we preach?   总被引:9,自引:5,他引:4       下载免费PDF全文
We used insurance claims from enrollees in the Rand Health Insurance Experiment to determine the amount of selected components of preventive care received by a representative sample of the non-aged population in the United States and to determine whether insurance coverage was an important determinant of that amount. Only 45 percent of infants received timely immunization for DPT and polio; 93 per cent received some well child care by 18 months of age. In the three-year experimental period, only 4 per cent of adults had a tetanus shot, 66 per cent of women aged 17-44 and 57 per cent aged 45-65 received a Pap smear, and 2 per cent of women aged 45-65 had a mammogram. Cost sharing was associated with even less preventive care: 60 per cent of children on the free plan and 49 per cent on cost sharing plans received preventive care of any type. For adults, women on the free plan received more preventive care of several kinds, and those aged 45-65 received more Pap smears than those on cost-sharing plans. Even with free care, most enrollees did not receive adequate preventive care. Thus, free care alone, while significant, is not a sufficient incentive to providing recommended levels of preventive care. The average per person insurance charge for increasing the amount of preventive care to a level consistent with that recommended would be $22 for a complete set of immunizations by age 18 months, $9 for a Pap smear every three years, and $97 for a Pap test and mammogram every three years.  相似文献   
23.
Thirty C57BI mice were randomized into two groups. Group 1 served as controls while Group 2 was given 10% V/V ethanol with the drinking water. Whole blood- associated acetaldehyde (WBAA) was measured on capillary blood samples using a fluorigenic high performance chromatographic assay. WBAA peaked at Day 2. A stable mean plateau of 263 +/- 71 SD with a range of 160-400 nmoles/g hemoglobin WBAA was found in the group consuming ethanol compared with 122 +/- 17 SD and a range of 88-150 nmoles/g hemoglobin for controls (p less than 0.001). When ethanol was discontinued, levels of WBAA declined and became similar to those of controls by 9 days following cessation of ethanol. The quantitative difference between ethanol-consuming and control animals and also the rapid rise of whole blood-associated acetaldehyde and the relatively slow decline following cessation of ethanol intake indicate that such a test might be a useful monitor of drinking behavior.  相似文献   
24.
25.
The authors measure the efficacy of three methods for predicting the time to infection for susceptible individuals in a population undergoing an HIV epidemic. The methods differ in whether they require detailed information of the contact network and whether they require knowledge of the initial source of infection. Efficacy is evaluated using simulations for 20 different contact patterns. Only the risk score that uses both kinds of information accounts for more than 15 per cent of individual variability. The efficacy of this score ranges from 10 per cent in very unstructured populations to 60 per cent for spatially localized contact networks. This improved performance may be explained by the larger fraction of the total variability not due to the disease dynamics. When all variables are dichotomized, the two poorer methods produce odds ratios between 1.4 and 2.3. The odds ratio for the risk score with full information ranges from 2.5 to 17. Risk assessment protocols and intervention programmes are encouraged to assess contact patterns and detect sources of infection.  相似文献   
26.
Specific proteolytic destruction of the human chemotaxin, C5a, is a property of group A and B streptococcal pathogens. Here we show that virulent group G streptococci from human sources also express C5a peptidase activity. The enzyme responsible for this activity is approximately the same size as and is antigenically similar to that produced by group A streptococci. On the basis of Southern hybridization analysis with an internal fragment of the group A C5a peptidase gene (scpA) as a probe, a copy of this gene was found in the genome of all group G human isolates tested. Comparison of partial restriction maps of scpA and scpG revealed significant similarity between the two genes. Group G strains isolated from dogs and cows were found to lack C5a peptidase activity and did not hybridize to the scpA-specific probe. The association of this activity with three streptococcal species suggests that elimination of phagocyte chemotactic attractants is a more universal virulence mechanism than originally anticipated.  相似文献   
27.
Analysis was made of the results of the treatment of 18 children afflicted with lymphoblastic lymphosarcoma, with estimation of predictors influencing the patients' survival (from 1980 to 1986). The most important predictors influencing the 2-year relapse-free survival were found to be the stage, localization of the process, the presence of the symptoms of intoxication and biological activity. The data obtained were used later in the treatment of 160 children during 1986 to 1989. The results of the 2-year survival of this patients' group appreciably differ from those derived before.  相似文献   
28.
29.
背景:图雷特综合征(TS)是一种儿童期发作的,以运动和语音性抽搐为特征的神经精神疾病。1/2~2/3患具有TS发作史的儿童,其抽搐症状在成年期缓解或完全缓解。至少1/3的TS成年患伴有强迫性神经失调(OCD)。目的:阐明TS患儿抽搐和OCD症状的临床过程;确定儿童期基线临床测量结果,是否与将来青春晚期和成人早期症状的严重程度有关。  相似文献   
30.
The vasoconstrictive peptide endothelin-1 (ET-1) has been reported to exert a very important positive inotropic effect in vitro. To assess the effect of ET-1 on myocardial contractility in vivo, we compared the effect of intracoronary infusion of 10(-8) M ET-1 (constant coronary blood flow) to that of 10(-8) M dobutamine in 8 swine. ET infusion did not produce changes in segmental shortening (control vs. drug, mean +/- SD): 33.8 +/- 14.3 vs. 30.8 +/- 12.1%, shortening velocity: 10.3 +/- 4.3 vs. 10.7 +/- 4.5 mm/s, or maximum +dP/dt: 1,691 +/- 701 vs. 1,772 +/- 773 mm Hg/s, whereas dobutamine infusion induced an important increase in these measurements; segmental shortening: 36.9 +/- 14 vs. 48.4 +/- 18.8%, shortening velocity: 10.1 +/- 2.6 vs. 14.7 +/- 4.5 mm/s, and maximum +dP/dt: 2,041 +/- 567 vs. 2,389 +/- 765 mm Hg/s (all p less than 0.05). Mean myocardial blood flow assessed by microspheres was unchanged by ET-1 despite a marked increase in coronary artery pressure (88.6 +/- 12.9 vs. 157 +/- 8.8 mm Hg, p less than 0.001). Regional infusion of ET-1 at a dose provoking extensive coronary vasoconstriction does not induce any change in regional or global myocardial function in swine.  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