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   2372381篇
  免费   198365篇
  国内免费   4217篇
耳鼻咽喉   34289篇
儿科学   72774篇
妇产科学   62952篇
基础医学   335085篇
口腔科学   67551篇
临床医学   215533篇
内科学   468492篇
皮肤病学   47953篇
神经病学   200915篇
特种医学   96072篇
外国民族医学   886篇
外科学   360704篇
综合类   56243篇
现状与发展   2篇
一般理论   983篇
预防医学   190556篇
眼科学   55494篇
药学   177601篇
  4篇
中国医学   4396篇
肿瘤学   126478篇
  2018年   24274篇
  2016年   20608篇
  2015年   23338篇
  2014年   33612篇
  2013年   50941篇
  2012年   68872篇
  2011年   72425篇
  2010年   42575篇
  2009年   40935篇
  2008年   68885篇
  2007年   73241篇
  2006年   74132篇
  2005年   72159篇
  2004年   69445篇
  2003年   67128篇
  2002年   66338篇
  2001年   112483篇
  2000年   116572篇
  1999年   98373篇
  1998年   27887篇
  1997年   25539篇
  1996年   25461篇
  1995年   24636篇
  1994年   23175篇
  1993年   21562篇
  1992年   79411篇
  1991年   76410篇
  1990年   73598篇
  1989年   70867篇
  1988年   65869篇
  1987年   64826篇
  1986年   61354篇
  1985年   58419篇
  1984年   44246篇
  1983年   37675篇
  1982年   22893篇
  1981年   20338篇
  1980年   19044篇
  1979年   41316篇
  1978年   29000篇
  1977年   24355篇
  1976年   22840篇
  1975年   23974篇
  1974年   29650篇
  1973年   28056篇
  1972年   26233篇
  1971年   24167篇
  1970年   22762篇
  1969年   21095篇
  1968年   19145篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
72.
73.
74.
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   
75.
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   
76.
77.
78.
79.
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   
80.
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