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   1977篇
  免费   139篇
  国内免费   6篇
耳鼻咽喉   7篇
儿科学   22篇
妇产科学   12篇
基础医学   377篇
口腔科学   177篇
临床医学   199篇
内科学   410篇
皮肤病学   27篇
神经病学   115篇
特种医学   95篇
外科学   277篇
综合类   32篇
一般理论   1篇
预防医学   173篇
眼科学   25篇
药学   86篇
中国医学   1篇
肿瘤学   86篇
  2021年   27篇
  2018年   27篇
  2016年   18篇
  2015年   22篇
  2014年   58篇
  2013年   70篇
  2012年   72篇
  2011年   80篇
  2010年   49篇
  2009年   33篇
  2008年   56篇
  2007年   49篇
  2006年   80篇
  2005年   77篇
  2004年   42篇
  2003年   37篇
  2002年   52篇
  2001年   42篇
  2000年   37篇
  1999年   62篇
  1998年   26篇
  1997年   29篇
  1996年   41篇
  1995年   33篇
  1994年   23篇
  1993年   25篇
  1992年   44篇
  1991年   46篇
  1990年   43篇
  1989年   42篇
  1988年   40篇
  1987年   46篇
  1986年   43篇
  1985年   40篇
  1984年   36篇
  1983年   35篇
  1982年   20篇
  1981年   20篇
  1980年   19篇
  1979年   23篇
  1978年   21篇
  1976年   28篇
  1975年   25篇
  1974年   42篇
  1973年   20篇
  1971年   23篇
  1970年   19篇
  1969年   20篇
  1967年   18篇
  1966年   29篇
排序方式: 共有2122条查询结果,搜索用时 31 毫秒
11.
12.
The automatic external defibrillator is a simple device that can be used by nonprofessional rescuers to treat cardiac arrest. In 1287 consecutive patients with out-of-hospital cardiac arrest, we assessed the results of initial treatment with this device by firefighters who arrived first at the scene, as compared with the results of standard defibrillation administered by paramedics who arrived slightly after the firefighters. Of 276 patients who were initially treated by firefighters using the automatic defibrillator, 84 (30 percent) survived to hospital discharge (expected rate according to a logistic model, 17 percent; P less than 0.001), as compared with 44 (19 percent) of 228 patients when fire-fighters delivered only basic cardiopulmonary resuscitation and the first defibrillation was performed after the arrival of the paramedic team. Few patients with conditions other than ventricular fibrillation survived. In a multivariate analysis of characteristics that influenced survival after ventricular fibrillation, a better survival rate was related to a witnessed collapse (odds ratio, 3.9; 95 percent confidence interval, 2.0 to 7.6), younger age (odds ratio, 1.2; 95 percent confidence interval, 1.0 to 1.4), the presence of "coarse" (higher-amplitude) fibrillation (odds ratio, 4.2; 95 percent confidence interval, 1.6 to 11.0), a shorter response time for paramedics (odds ratio, 1.4; 95 percent confidence interval, 1.0 to 2.1), and initial treatment by firefighters using an automatic external defibrillator (odds ratio, 1.8; 95 percent confidence interval, 1.1 to 2.9). These findings support the widespread use of the automatic external defibrillator as an important part of the treatment of out-of-hospital cardiac arrest, although the overall impact of the use of this device on community survival rates is still uncertain.  相似文献   
13.
We investigated cystic fibrosis (CF) transmembrane conductance regulator (CFTR) regulation by A2 adenosine (Ado) receptors and beta2 adrenergic receptors in CFTR-corrected CFBE41o- airway cells and human subjects. CFBE41o- cells stimulated with Ado (10 microM), isoproterenol (Iso, 10 microM), or Ado + Iso (10 microM each) elevated cyclic AMP (cAMP) above control conditions (P < 0.001), with the Iso conditions increasing cAMP approximately 10-fold above that produced by Ado alone (P < 0.001). All agonist conditions had similar effects on short circuit current at 10 and 25 microM, with no further currents produced by subsequent stimulation with forskolin (20 microM). CFTR dependence was demonstrated by glybenclamide block of agonist-stimulated currents. Nasal potential difference studies in normal (n = 50) subjects demonstrated that Ado (10 microM) and Ado + Iso (10 microM each) produced more polarization compared with Iso (10 microM Ado increase = 44%, 10 microM Ado + Iso increase = 52%, P < 0.05 for each condition compared with Iso alone). Studies completed in patients with CF (n = 10, "severe" genotypes) confirmed that Ado-stimulated polarization was CFTR-dependent. Together, these results indicate that Ado is a potent Cl- secretagogue in vivo, with relatively small effects on cAMP levels despite strong effects on CFTR-dependent short circuit current and nasal Cl- transport. These findings support growing evidence indicating a role for Ado regulation of CFTR-dependent Cl- secretion in vivo.  相似文献   
14.
15.
Recent advances in the development of transducers for the measurement of vertical and shear forces acting on the plantar surface of the foot are reviewed. Barefoot and in-shoe discrete and matrix transducers are reviewed in terms of structure, operation, performance and limitations. Examples of capacitive, piezoelectric, optical, conductive and resistive types of transducer are presented. Where available, the current clinical status is specified.  相似文献   
16.
17.
18.
19.
Urine samples from 50 patients attending a genitourinary outpatient clinic and from 13 renal allograft recipients were investigated for evidence of infection with human BK and JC polyomaviruses using cytology and a new DNA hybridot assay. Forty four per cent of samples from the renal allograft recipients were positive by cytology and 75% by DNA hybridisation, indicating that hybridot assay is more sensitive than cytological screening. BK and JC viral DNA was found in 20% of the patients attending the genitourinary clinic, showing infection with BK virus and JC virus in a group of patients with clinical conditions not normally associated with immunological deficiency-a finding that has not been reported before.  相似文献   
20.
Prevention Science - We examined national trends and mental health correlates of discrimination among Latinos in the USA. We used data from two nationally representative surveys based on the...  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