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   2397814篇
  免费   200383篇
  国内免费   4234篇
耳鼻咽喉   34573篇
儿科学   73568篇
妇产科学   63578篇
基础医学   338181篇
口腔科学   68179篇
临床医学   218819篇
内科学   473146篇
皮肤病学   48322篇
神经病学   203569篇
特种医学   97121篇
外国民族医学   889篇
外科学   363939篇
综合类   56640篇
现状与发展   1篇
一般理论   1010篇
预防医学   193299篇
眼科学   56217篇
药学   179186篇
  6篇
中国医学   4397篇
肿瘤学   127791篇
  2018年   24626篇
  2016年   20932篇
  2015年   23673篇
  2014年   34128篇
  2013年   51753篇
  2012年   70046篇
  2011年   73673篇
  2010年   43249篇
  2009年   41553篇
  2008年   70013篇
  2007年   74522篇
  2006年   75318篇
  2005年   73274篇
  2004年   70564篇
  2003年   68105篇
  2002年   67405篇
  2001年   113107篇
  2000年   117220篇
  1999年   98951篇
  1998年   28185篇
  1997年   25811篇
  1996年   25728篇
  1995年   24870篇
  1994年   23401篇
  1993年   21764篇
  1992年   79904篇
  1991年   76935篇
  1990年   74060篇
  1989年   71383篇
  1988年   66259篇
  1987年   65283篇
  1986年   61755篇
  1985年   58882篇
  1984年   44579篇
  1983年   37983篇
  1982年   23123篇
  1981年   20563篇
  1980年   19246篇
  1979年   41675篇
  1978年   29269篇
  1977年   24610篇
  1976年   23089篇
  1975年   24179篇
  1974年   29924篇
  1973年   28317篇
  1972年   26451篇
  1971年   24356篇
  1970年   22917篇
  1969年   21253篇
  1968年   19305篇
排序方式: 共有10000条查询结果,搜索用时 312 毫秒
71.
72.
73.
74.
75.
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   
76.
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   
77.
78.
79.
80.
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   
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