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   216206篇
  免费   15555篇
  国内免费   774篇
耳鼻咽喉   2359篇
儿科学   5623篇
妇产科学   4528篇
基础医学   27968篇
口腔科学   4677篇
临床医学   20481篇
内科学   45938篇
皮肤病学   2908篇
神经病学   20736篇
特种医学   7124篇
外国民族医学   13篇
外科学   33761篇
综合类   3524篇
现状与发展   2篇
一般理论   293篇
预防医学   19688篇
眼科学   4487篇
药学   14903篇
  1篇
中国医学   438篇
肿瘤学   13083篇
  2023年   880篇
  2022年   1493篇
  2021年   3620篇
  2020年   2196篇
  2019年   3545篇
  2018年   4163篇
  2017年   3347篇
  2016年   3535篇
  2015年   4247篇
  2014年   6294篇
  2013年   9087篇
  2012年   13568篇
  2011年   14793篇
  2010年   8336篇
  2009年   7482篇
  2008年   13916篇
  2007年   14762篇
  2006年   14219篇
  2005年   14665篇
  2004年   14101篇
  2003年   13120篇
  2002年   12670篇
  2001年   2046篇
  2000年   1668篇
  1999年   2196篇
  1998年   2871篇
  1997年   2467篇
  1996年   2233篇
  1995年   1975篇
  1994年   1773篇
  1993年   1678篇
  1992年   1279篇
  1991年   1202篇
  1990年   1112篇
  1989年   1011篇
  1988年   1055篇
  1987年   1060篇
  1986年   1037篇
  1985年   1114篇
  1984年   1498篇
  1983年   1485篇
  1982年   1829篇
  1981年   1651篇
  1980年   1557篇
  1979年   826篇
  1978年   976篇
  1977年   944篇
  1976年   845篇
  1975年   692篇
  1974年   683篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
41.
OBJECTIVE: To assess the impact of activity restriction (AR) on the incidence of preterm birth in women treated for preterm labor testing negative for fetal fibronectin (fFN). STUDY DESIGN: Women who were diagnosed with preterm labor and tocolyzed with magnesium sulfate were concurrently screened with fFN for the purpose of subsequent management. Included were consenting patients with negative fFN, gestational age 23 0/7-33 6/7 weeks, cervical dilation < or =3 cm, and minimal vaginal bleeding. Patients were randomized to AR or no AR. Primary study outcome was incidence of preterm delivery and interval from randomization to delivery. RESULTS: A total of 73 women with negative fFN were randomized (36 with AR, 37 without AR). The overall preterm birth rate was 40%, with 44.4% of patients with AR and 35.1% of patients without AR delivering preterm, p=0.478. CONCLUSION: Maternal AR did not impact pregnancy outcome. The incidence of preterm birth in symptomatic women testing fFN negative was higher than previously reported.  相似文献   
42.
43.
Pryor  John 《JAMA》2006,296(19):2379
  相似文献   
44.
45.
Event-related brain potentials (ERPs) were recorded during a computerized and modified version of the Digit Span Backwards (DB) task from the Wechsler Adult Intelligence Scale-Third Edition (WAIS-III). The modified DB version (ERP-DB task) was divided into two sections of 2, 4, 6 and 8 digits in length (Group 1) and 3, 5 and 7 digits in length (Group 2). Each trial had a study phase and a test phase. For the study phase, a series of digits was presented sequentially and aurally to 20 participants (10 for each group). For the test phase, a second series of digits was also presented sequentially and aurally that either corresponded to the reverse order of the digits in the study phase (correct condition) or had one digit in the sequence replaced by an incorrect digit (incorrect condition). The traditional DB task of the WAIS-III was also administered for comparison purposes. A prolonged positive slow wave (PSW) peaking between 450 and 750 ms was elicited to incorrect condition trials. For each participant, a derived measure was calculated from the ERP differentiation between correct and incorrect conditions. The derived measure was defined as the mean of the t-values obtained from the correct and incorrect waveform comparison, within the temporal interval that encompassed this component. The strongest statistical correlations between the derived measure and the traditional DB test scores were found at the Pz site (Group 1: r=0.79; Group 2: r=0.59). This statistical approach shows that it is possible to adequately relate an individual's performance on a traditional measure of working memory and ERP patterns. Overall, we believe that this kind of ERP approach holds promise as a technique for assessing quantitatively non-communicative patients.  相似文献   
46.
47.
I enjoyed reading the contribution by Nieminen et al.1 focusingon the predictive role for cardiovascular mortality, especiallysudden cardiac death, of the T-wave alternans (TWA) calculatedby the analytical  相似文献   
48.
This study compared the predictive value of the theory of planned behavior in university students in South Africa (N = 251) and the United States (N = 160) who completed an anonymous self-administered questionnaire. Multiple regression analyses revealed that condom use and intention were significantly predicted by positive condom attitude, subjective norm, self-efficacy, and attending university in South Africa. Significant interactions between country and predictors indicated that subjective norm predicted condom use and intention more strongly in the American sample than in the South African sample; attitude predicted intention more strongly in the American sample than in the South African sample; but self-efficacy predicted intention more strongly in the South African sample than in the American sample. The theory of planned behavior may provide a useful framework for interventions to reduce South African students' risk of HIV/and sexuality transmitted diseases. Such interventions should especially focus on building self-efficacy to use condoms.  相似文献   
49.
Two hundred and thirty pregnancies were studied in 196 diabetic women. Seven women with babies found to have major malformations had a higher median first trimester haemoglobin A1 (12.9%) than the median HbA1 (10.8%) in those with normal babies (p = 0.06). No relationship was found between the occurrence of minor malformations and first trimester maternal haemoglobin A1. Two of the seven congenital malformations were diagnosed antenatally at a time when therapeutic abortion could be offered. Expert antenatal ultrasound scanning should be offered to all pregnant diabetic women as poor glycaemic control at the time of conception and organogenesis, as evidenced by raised first trimester HbA1, predisposes to congenital malformation.  相似文献   
50.
Forty-nine children with asthma and their mothers were interviewed regarding their knowledge of asthma, factors that precipitated attacks, and how they attempted to reduce the probability of an attack. Many mothers and children were well aware of factors that precipitated attacks, but took little positive action to reduce attacks. The data suggest that much ill-health in asthmatic children could be reduced by improving education available to mothers and children.  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