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   211968篇
  免费   15423篇
  国内免费   750篇
耳鼻咽喉   2296篇
儿科学   5813篇
妇产科学   4337篇
基础医学   27258篇
口腔科学   4524篇
临床医学   20148篇
内科学   45156篇
皮肤病学   2763篇
神经病学   20411篇
特种医学   6986篇
外国民族医学   14篇
外科学   33235篇
综合类   3458篇
现状与发展   2篇
一般理论   293篇
预防医学   19166篇
眼科学   4392篇
药学   14446篇
  1篇
中国医学   375篇
肿瘤学   13067篇
  2023年   848篇
  2022年   1413篇
  2021年   3458篇
  2020年   2122篇
  2019年   3405篇
  2018年   4011篇
  2017年   3256篇
  2016年   3461篇
  2015年   4109篇
  2014年   6141篇
  2013年   8890篇
  2012年   13200篇
  2011年   14396篇
  2010年   8150篇
  2009年   7358篇
  2008年   13646篇
  2007年   14494篇
  2006年   13974篇
  2005年   14464篇
  2004年   13883篇
  2003年   12965篇
  2002年   12492篇
  2001年   1936篇
  2000年   1522篇
  1999年   2087篇
  1998年   2844篇
  1997年   2454篇
  1996年   2228篇
  1995年   1966篇
  1994年   1764篇
  1993年   1667篇
  1992年   1252篇
  1991年   1190篇
  1990年   1100篇
  1989年   986篇
  1988年   1055篇
  1987年   1060篇
  1986年   1036篇
  1985年   1107篇
  1984年   1503篇
  1983年   1472篇
  1982年   1820篇
  1981年   1652篇
  1980年   1564篇
  1979年   835篇
  1978年   975篇
  1977年   946篇
  1976年   844篇
  1975年   702篇
  1974年   686篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
92.
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   
93.
94.
Pryor  John 《JAMA》2006,296(19):2379
  相似文献   
95.
96.
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   
97.
98.
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   
99.
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   
100.
Alemtuzumab is a powerful lymphocyte depleting antibody currently being evaluated in solid organ transplantation. This paper describes 5-year results of a single center study of alemtuzumab as induction in renal transplantation. Thirty-three renal transplant recipients received 20 mg alemtuzumab on day 0 and 1, followed by half-dose cyclosporin monotherapy (trough concentration 75-125 ng/mL) from day 3. They were compared in a retrospective contemporaneous-controlled manner with 66 kidney transplant recipients transplanted in the same period and center who received conventional immunosuppression with cyclosporin, azathioprine and prednisolone. In the alemtuzumab group 12% of recipients died compared to 17% in the control group (p = 0.48); likewise graft loss was similar in both groups (21% vs. 26%, respectively, p = 0.58). Incidence of acute rejection was also comparable at 5 years (31.5% vs. 33.6%), although the pattern of rejection was different with 14% patients in the alemtuzumab group experiencing rejection over 1 year post-transplant compared to none in the control group. There was no significant difference between groups in terms of infection or serious adverse events. While acknowledging the limitations of a relatively small single-center study, results suggest that alemtuzumab induction allowed satisfactory long-term patient and graft survival equivalent to that seen with standard triple immunosuppression, while avoiding steroid therapy.  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