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   38070篇
  免费   3376篇
  国内免费   76篇
耳鼻咽喉   303篇
儿科学   1334篇
妇产科学   1216篇
基础医学   4970篇
口腔科学   608篇
临床医学   6232篇
内科学   6892篇
皮肤病学   483篇
神经病学   3444篇
特种医学   844篇
外科学   3691篇
综合类   687篇
一般理论   71篇
预防医学   4996篇
眼科学   445篇
药学   2451篇
中国医学   29篇
肿瘤学   2826篇
  2023年   207篇
  2022年   286篇
  2021年   625篇
  2020年   509篇
  2019年   860篇
  2018年   883篇
  2017年   683篇
  2016年   776篇
  2015年   884篇
  2014年   1151篇
  2013年   1775篇
  2012年   2446篇
  2011年   2502篇
  2010年   1369篇
  2009年   1244篇
  2008年   2295篇
  2007年   2439篇
  2006年   2436篇
  2005年   2310篇
  2004年   2185篇
  2003年   2087篇
  2002年   1992篇
  2001年   557篇
  2000年   534篇
  1999年   528篇
  1998年   517篇
  1997年   389篇
  1996年   402篇
  1995年   363篇
  1994年   323篇
  1993年   326篇
  1992年   363篇
  1991年   360篇
  1990年   328篇
  1989年   306篇
  1988年   316篇
  1987年   309篇
  1986年   299篇
  1985年   323篇
  1984年   256篇
  1983年   248篇
  1982年   229篇
  1981年   213篇
  1980年   202篇
  1979年   155篇
  1978年   142篇
  1977年   133篇
  1976年   131篇
  1975年   128篇
  1973年   120篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
21.
22.
We have previously reported the time trends, design and interventions in randomised controlled trials (RCTs) in cystic fibrosis (CF) from 1961 through 1997 [Cheng K, Smyth RL, Motley J, O'Hea U, Ashby D, Randomised controlled trials in cystic fibrosis (1966-1997) categorized by time, design, and intervention. Pediatr Pulmonol 2000, 29:1-7.]. We maintain an ongoing register of all RCTs and controlled clinical trials (CCTs) in CF and have noted that in the five years since 1997 there has been a 48% increase in published trials. We aimed to assess whether this increase has been associated with an improvement in design quality. All RCTs and CCTs from 1961-2002 were assessed. Two epochs were then compared, 1961-1997 and 1998-2002. For each trial we recorded the design, participant numbers and the intervention studied. 261 trials in 1998-2002 were compared with 544 trials in 1961-1997. Comparing the two epochs a similar proportion of trials were parallel, double-blind and placebo controlled; also the median number of participants was similar. In the later epoch 25% of trials were multicentre, compared with 11% previously. Whilst this recent increase in clinical trials in CF is welcome, this has not been associated with improvements in quality. The trend for an increasing proportion of trials to be multicentre is encouraging. There are however, still deficiencies in the design of clinical trials in CF.  相似文献   
23.
This is the third and final part of a series of articles that report the findings of a study that investigated the effects of a summer externship program on the transition into a professional role among nurses who participated in a summer nurse externship program at an acute care pediatric hospital. Specifically, this article reports the retention and recruitment benefits of a summer nurse externship program for the institution from 1998 through 2003. A total of 153 externs out of the 193 (79.0%) assumed a registered nurse position at the institution, and 77% remained in that role for 12 months. Overall, the nurse extern program for this institution appeared to be an effective recruitment and retention strategy that is on par with the institution and national data for retention and turnover data.  相似文献   
24.
AIMS: To examine the effects of agents that alter potassium adenosine triphosphate (KATP) channel activity in beta-cells on cognitive function and counterregulatory hormone responses during acute hypoglycaemia, given the physiological similarities between the pancreatic beta-cell and the hypothalamic glucose-sensitive neurones (GSN) and the widespread distribution of sulphonylurea receptors in neuronal cells throughout the brain. METHODS: Ten healthy males were studied on four occasions and in random order underwent three stepped hypoglycaemic (plasma glucose aims: 3.4, 2.8, 2.4 mmol/l) and one euglycaemic (plasma glucose aim: 5 mmol/l) insulin clamps. Prior to each hypoglycaemic study, volunteers received either 10 mg glibenclamide, or 5 mg/kg diazoxide or placebo orally. Cognitive function, symptom scores and counterregulatory hormone responses were measured at each glycaemic level. RESULTS: There was no statistically significant effect of either drug on the symptoms generated or the counterregulatory hormonal response during hypoglycaemia. However, cognitive function was better preserved during hypoglycaemia in the glibenclamide-treated arm, particularly four-choice reaction time which deteriorated at a plasma glucose 2.5 mmol/l compared with 3.0 mmol/l with diazoxide (P = 0.015) and 2.9 mmol/l with placebo (P = 0.114). CONCLUSIONS: Single doses of pharmacological agents which alter membrane KATP channel activity do not affect the counterregulatory response to hypoglycaemia but may modify cognitive function during cerebral glucopenia. The unexpected effects of glibenclamide on cortical function suggest a novel action of sulphonylureas that warrants further investigation.  相似文献   
25.
26.
27.
28.
An exaggerated fall in blood pressure has been reported with the combination of an alpha 1-blocker and a calcium antagonist. This study investigated, in a placebo-controlled, randomized crossover trial, the clinical usefulness of the combination of prazosin (2 mg b.i.d.) and verapamil (160 mg b.i.d.). Therapeutic efficacy was monitored at regular outpatient visits: average supine and erect blood pressures were, respectively, 175/99 and 176/103 mm Hg with placebo, 160/91 and 164/96 mm Hg with single drug treatment, and 152/84 and 152/89 mm Hg with combination therapy. This significant and clinically useful reduction in blood pressure had an overall magnitude of approximately 28/18 mm Hg (supine) and 29/19 mm Hg (erect). Further measurements were made during a series of intensive study days, and the most important additional finding was a pharmacokinetic interaction that resulted in increased peak concentrations and bioavailability of prazosin. In conclusion, the combination of prazosin and verapamil proved effective in the treatment of 12 patients with essential hypertension who had been poorly responsive to conventional treatment with a beta-blocker and thiazide diuretic.  相似文献   
29.
This study investigated analogical reasoning abilities of alcoholics who had been abstinent from alcohol for at least 1 year. Their performance was compared to that of nonalcoholic controls matched as a group for education, age, and gender. Solution times and error rates were modeled using a regression model. Results showed a nonsignificant trend for alcoholics to be faster, but more error prone, than controls. The same componential model applied to both groups, and fit them equally well. Although differences have been found in analogical reasoning ability between controls and alcoholics immediately following detoxification, we find no evidence of differences after extended periods of sobriety.  相似文献   
30.
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