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   2656494篇
  免费   206502篇
  国内免费   4689篇
耳鼻咽喉   36747篇
儿科学   82085篇
妇产科学   67825篇
基础医学   368694篇
口腔科学   71655篇
临床医学   238045篇
内科学   522061篇
皮肤病学   51221篇
神经病学   227007篇
特种医学   108980篇
外国民族医学   894篇
外科学   407016篇
综合类   60187篇
现状与发展   1篇
一般理论   1058篇
预防医学   215806篇
眼科学   60548篇
药学   194380篇
  4篇
中国医学   5179篇
肿瘤学   148292篇
  2018年   47588篇
  2017年   37315篇
  2016年   41967篇
  2015年   26802篇
  2014年   37903篇
  2013年   56561篇
  2012年   82361篇
  2011年   99708篇
  2010年   64311篇
  2009年   56118篇
  2008年   94674篇
  2007年   102298篇
  2006年   81753篇
  2005年   81934篇
  2004年   79941篇
  2003年   78579篇
  2002年   75444篇
  2001年   114161篇
  2000年   118250篇
  1999年   99888篇
  1998年   29436篇
  1997年   26915篇
  1996年   26516篇
  1995年   25649篇
  1994年   24140篇
  1993年   22389篇
  1992年   80257篇
  1991年   77215篇
  1990年   74309篇
  1989年   71491篇
  1988年   66476篇
  1987年   65410篇
  1986年   61920篇
  1985年   58970篇
  1984年   44838篇
  1983年   38205篇
  1982年   23605篇
  1981年   20939篇
  1980年   19660篇
  1979年   41790篇
  1978年   29475篇
  1977年   24730篇
  1976年   23231篇
  1975年   24258篇
  1974年   30027篇
  1973年   28339篇
  1972年   26486篇
  1971年   24347篇
  1970年   22981篇
  1969年   21274篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
92.
Red cell exchange (RCE) is a common procedure in adults with sickle cell disease (SCD). Implantable dual lumen Vortex (DLV) ports can be used for RCE in patients with poor peripheral venous access. We performed a retrospective cohort study of RCE procedures performed in adults with SCD. The main objective of the study was to compare the inlet speed, duration of procedures and rate of complications performed through DLV ports to those performed through temporary central venous and peripheral catheters. Twenty‐nine adults with SCD underwent a total of 318 RCE procedures. Twenty adults had DLV ports placed and 218 procedures were performed using DLV ports. Mean length of follow‐up after DLV port placement was 397 ± 263 days. Six DLV ports were removed due to infection and 1 for malfunction after a mean of 171 ± 120 days. Compared to temporary central venous and peripheral catheters, DLV port procedures had a greater rate of procedural complications, a longer duration, and a lower inlet speed (all P < 0.01). When accounting for the maximum allowable inlet speed to avoid citrate toxicity, 40% of DLV port procedures were greater than 10% below maximum speed, compared to 7 and 14% of procedures performed through temporary central venous and peripheral catheters (P < 0.0001). In conclusion, DLV ports can be used for RCE in adults with SCD, albeit with more procedural complications and longer duration. The smaller internal diameter and longer catheter of DLV ports compared to temporary central venous catheters likely accounts for the differences noted. J. Clin. Apheresis 30:353–358, 2015. © 2015 Wiley Periodicals, Inc.  相似文献   
93.
The catechol-O-methyltransferase (COMT) enzyme is a major determinant of prefrontal dopamine levels. The Val158Met polymorphism affects COMT enzymatic activity and has been associated with variation in executive function and affective processing. This study investigated the effect of COMT genotype on the flexible modulation of the balance between processing self-generated and processing stimulus-oriented information, in the presence or absence of affective distractors. Analyses included 124 healthy adult participants, who were also assessed on standard working memory (WM) tasks. Relative to Val carriers, Met homozygotes made fewer errors when selecting and manipulating self-generated thoughts. This effect was partly accounted for by an association between COMT genotype and visuospatial WM performance. We also observed a complex interaction between the influence of affective distractors, COMT genotype and sex on task accuracy: male, but not female, participants showed a sensitivity to the affective distractors that was dependent on COMT genotype. This was not accounted for by WM performance. This study provides novel evidence of the role of dopaminergic genetic variation on the ability to select and manipulate self-generated thoughts. The results also suggest sexually dimorphic effects of COMT genotype on the influence of affective distractors on executive function.  相似文献   
94.
95.
96.
97.
98.
The value of adding simeprevir (SMV) vs placebo (PBO) to peginterferon and ribavirin (PR) for treatment of chronic hepatitis C virus infection was examined using patient‐reported outcomes (PROs); further, concordance of PROs with virology endpoints and adverse events (AEs) was explored. Patients (= 768 SMV/PR,= 393 PBO/PR) rated fatigue (FSS), depressive symptoms (CES‐D) and functional impairment (WPAI: Hepatitis C Productivity, Daily Activity and Absenteeism) at baseline and throughout treatment in three randomised, double‐blind trials comparing the addition of SMV or PBO during initial 12 weeks of PR. PR was administered for 48 weeks (PBO group) and 24/48 weeks (SMV group) using a response‐guided therapy (RGT) approach. Mean PRO scores (except Absenteeism) worsened from baseline to Week 4 to the same extent in both groups but reverted after Week 24 for SMV/PR and only after Week 48 for PBO/PR. Accordingly, there was a significantly lower area under the curve (baseline–Week 60, AUC60) and fewer weeks with clinically important worsening of scores in the SMV/PR group at any time point. Incidences of patients with fatigue and anaemia AEs were similar in both groups, but FSS scores showed that clinically important increases in fatigue lasted a mean of 6.9 weeks longer with PBO/PR (P < 0.001). PRO score subgroup analysis indicated better outcomes for patients who met the criteria for RGT or achieved sustained virological response 12 weeks post‐treatment (SVR12); differences in mean PRO scores associated with fibrosis level were only observed with PBO/PR. Greater efficacy of SMV/PR enabled reduced treatment duration and reduced time with PR‐related AEs without adding to AE severity.  相似文献   
99.
100.
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