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   2670518篇
  免费   228237篇
  国内免费   21736篇
耳鼻咽喉   37435篇
儿科学   77682篇
妇产科学   64647篇
基础医学   352255篇
口腔科学   73649篇
临床医学   250798篇
内科学   492748篇
皮肤病学   51325篇
神经病学   207062篇
特种医学   108484篇
外国民族医学   886篇
外科学   385436篇
综合类   141996篇
现状与发展   72篇
一般理论   977篇
预防医学   225229篇
眼科学   58775篇
药学   214721篇
  511篇
中国医学   36457篇
肿瘤学   139346篇
  2021年   28379篇
  2019年   22730篇
  2018年   30394篇
  2017年   27318篇
  2016年   27086篇
  2015年   35280篇
  2014年   48765篇
  2013年   70517篇
  2012年   96952篇
  2011年   102075篇
  2010年   69354篇
  2009年   65064篇
  2008年   93539篇
  2007年   96693篇
  2006年   94739篇
  2005年   88161篇
  2004年   80579篇
  2003年   76082篇
  2002年   73077篇
  2001年   118867篇
  2000年   121128篇
  1999年   100002篇
  1998年   28186篇
  1997年   25803篇
  1996年   25728篇
  1995年   24815篇
  1994年   23388篇
  1993年   21675篇
  1992年   79488篇
  1991年   76496篇
  1990年   73652篇
  1989年   70896篇
  1988年   65879篇
  1987年   64856篇
  1986年   61375篇
  1985年   58444篇
  1984年   44253篇
  1983年   37691篇
  1982年   22912篇
  1979年   41299篇
  1978年   28986篇
  1977年   24346篇
  1976年   22834篇
  1975年   23965篇
  1974年   29639篇
  1973年   28044篇
  1972年   26226篇
  1971年   24151篇
  1970年   22753篇
  1969年   21088篇
排序方式: 共有10000条查询结果,搜索用时 343 毫秒
101.
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   
102.
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   
103.
104.
105.
106.
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   
107.
108.
109.
刘峰 《新中医》2021,53(18):41-44
目的:观察益心舒胶囊联合常规疗法治疗非瓣膜性心房颤动的疗效。方法:纳入96 例气阴亏虚兼瘀血内阻型非瓣膜性心房颤动患者,采用随机数字表法分为对照组和观察组各48 例。2 组患者均予常规降压、降糖、调脂以及调整心态、饮食等治疗措施,并服用华法林钠片治疗,观察组加予益心舒胶囊治疗。2 组疗程均为3 个月。观察2 组治疗前及治疗3 个月后凝血功能指标、心房颤动发作情况、血浆N 末端B 型利钠肽原(NT-proBNP) 以及血液流变学水平的变化。结果:治疗后,2 组凝血酶原时间(PT)、活化部分凝血活酶时间(APTT)、凝血酶时间(TT)、国际标准化比值(INR) 均较治疗前增加(P<0.01),观察组PT、APTT、TT、INR 均长于或高于对照组(P<0.01)。2 组心房颤动发作时间与发作频率均较治疗前缩短或降低(P<0.01),观察组心房颤动发作时间与发作频率均短于或低于对照组(P<0.01)。2 组血浆NT-proBNP 水平均较治疗前降低(P<0.01),观察组血浆NT-proBNP 水平均低于对照组(P<0.01)。2 组红细胞比容(HCT)、纤维蛋白原(Fb)、全血黏度、血浆比黏度均较治疗前降低(P<0.01),观察组4 项指标值均低于对照组(P<0.01)。结论:在常规治疗基础上加服益心舒胶囊治疗气阴亏虚兼瘀血内阻型非瓣膜性心房颤动,在改善患者的凝血功能、心功能以及缓解临床症状方面疗效明显,且可有效改善血液流变学水平。  相似文献   
110.
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