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   2955753篇
  免费   241959篇
  国内免费   5772篇
耳鼻咽喉   43471篇
儿科学   90025篇
妇产科学   79450篇
基础医学   418397篇
口腔科学   85674篇
临床医学   269143篇
内科学   574072篇
皮肤病学   60114篇
神经病学   250238篇
特种医学   118511篇
外国民族医学   1044篇
外科学   449349篇
综合类   73325篇
现状与发展   3篇
一般理论   1229篇
预防医学   239333篇
眼科学   70656篇
药学   220486篇
  4篇
中国医学   5448篇
肿瘤学   153512篇
  2018年   30273篇
  2016年   26043篇
  2015年   29613篇
  2014年   42449篇
  2013年   64423篇
  2012年   87132篇
  2011年   91698篇
  2010年   54031篇
  2009年   51595篇
  2008年   86703篇
  2007年   92939篇
  2006年   93198篇
  2005年   91021篇
  2004年   87982篇
  2003年   84697篇
  2002年   83377篇
  2001年   130915篇
  2000年   135289篇
  1999年   114704篇
  1998年   34263篇
  1997年   31183篇
  1996年   30623篇
  1995年   29625篇
  1994年   27850篇
  1993年   25933篇
  1992年   93497篇
  1991年   90233篇
  1990年   87305篇
  1989年   84090篇
  1988年   78395篇
  1987年   77366篇
  1986年   73199篇
  1985年   70293篇
  1984年   53754篇
  1983年   45962篇
  1982年   28537篇
  1981年   25494篇
  1980年   23966篇
  1979年   51475篇
  1978年   36504篇
  1977年   30777篇
  1976年   28730篇
  1975年   30489篇
  1974年   37696篇
  1973年   36031篇
  1972年   33765篇
  1971年   31187篇
  1970年   29521篇
  1969年   27761篇
  1968年   25231篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
91.
92.
93.
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   
94.
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   
95.
96.
97.
98.
99.
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   
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