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   1306942篇
  免费   97681篇
  国内免费   2513篇
耳鼻咽喉   16664篇
儿科学   42104篇
妇产科学   36043篇
基础医学   194127篇
口腔科学   35592篇
临床医学   121569篇
内科学   257925篇
皮肤病学   27950篇
神经病学   105759篇
特种医学   48356篇
外国民族医学   267篇
外科学   184368篇
综合类   27817篇
现状与发展   4篇
一般理论   569篇
预防医学   106894篇
眼科学   28649篇
药学   96159篇
  15篇
中国医学   2979篇
肿瘤学   73326篇
  2021年   11089篇
  2019年   11107篇
  2018年   14766篇
  2017年   11405篇
  2016年   12405篇
  2015年   14452篇
  2014年   19738篇
  2013年   29633篇
  2012年   40445篇
  2011年   42835篇
  2010年   24762篇
  2009年   23827篇
  2008年   40119篇
  2007年   42805篇
  2006年   42170篇
  2005年   41153篇
  2004年   39432篇
  2003年   37572篇
  2002年   36332篇
  2001年   57087篇
  2000年   58047篇
  1999年   49057篇
  1998年   13799篇
  1997年   12534篇
  1996年   12948篇
  1995年   12156篇
  1994年   11334篇
  1992年   38716篇
  1991年   38118篇
  1990年   36883篇
  1989年   35694篇
  1988年   33046篇
  1987年   32363篇
  1986年   30831篇
  1985年   29052篇
  1984年   22157篇
  1983年   19362篇
  1982年   11466篇
  1979年   21128篇
  1978年   15505篇
  1977年   12884篇
  1976年   11919篇
  1975年   12886篇
  1974年   15685篇
  1973年   15467篇
  1972年   14610篇
  1971年   13645篇
  1970年   12871篇
  1969年   12145篇
  1968年   11301篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
102.
OBJECTIVE: To evaluate the reproducibility of sonographic measurement of the lower uterine segment in pregnant women at term. METHODS: Two independent observers performed transabdominal sonography on 129 women between 36 and 38 weeks of gestation who had had a previous Cesarean section. Sonography was performed when the patients had a full and a half-full bladder; in 100 patients, the measurements were also performed transvaginally, with the patients having an empty bladder. Agreement was quantified by the intraclass correlation coefficient and, using a cut-off of 3.5 mm, by the kappa coefficient. RESULTS: The intraobserver agreement was generally high (intraclass correlation coefficient > 0.90). The interobserver agreement was higher on transvaginal (intraclass correlation coefficient, 0.94) compared with transabdominal (0.70 and 0.84, with full and half-full bladder, respectively) ultrasound. The kappa coefficient was 0.75 transvaginally, compared with 0.34 and 0.54 using the transabdominal approach, with full and half-full bladder, respectively. CONCLUSION: The agreement between two observers for sonographic transvaginal measurement of the lower uterine segment can be considered good, compared with poor to moderate agreement using the transabdominal approach.  相似文献   
103.
104.
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   
105.
The incidence of asthma has been reported to be associated with obesity. An alternative analysis, of net change in prevalence, does not require exclusion of those with asthma at baseline. Follow-up data were obtained from 9,552 participants in the European Community Respiratory Health Survey and the Swiss cohort Study on Air Pollution and Lung Disease in Adults. Incidence of asthma was analysed by proportional hazards regression, and net changes in symptoms and asthma status by generalised estimating equations, by obesity group. Incidence and net change in ever having had asthma were greater in females than in males, and in participants who remained obese compared with those who were never obese (hazard ratio 2.00, 95% confidence interval 1.25-3.20; excess net change 2.8%, 0.4-5.3% per 10 yrs). The effect of being obese on net change in diagnosed asthma was greater in females than in males, but for net change in wheeze without a cold it was greater in males. The present results are consistent with asthma being more frequently diagnosed in females, especially obese females. These findings may help to explain the reports of a stronger association between asthma and obesity in females than in males.  相似文献   
106.
Esophageal foreign body causing direct aortic injury.   总被引:4,自引:0,他引:4  
Foreign bodies in the esophagus are uncommon causes of esophageal perforation. Many nonperforating cases are successfully managed by flexible gastroscopy. However, complicated foreign bodies such as those that result in esophageal perforation and vascular injury are best managed surgically. Gastroscopy remains the primary method of diagnosis. A case of a 59-year-old woman who developed retrosternal and intrascapular pain, odynophagia and hematemesis after eating fish is reported. Flexible gastroscopy showed arterial bleeding from the midthoracic esophagus. Computed tomography scan localized a 3 cm fish bone perforating the esophagus with surrounding hematoma. An aortogram did not reveal an actively bleeding aortoesophageal fistula. The fish bone was surgically removed and the patient recovered with no postoperative complications. This case illustrates the importance of early consideration for surgical intervention when confronted with a brisk arterial bleed from the esophagus with suggestive history of foreign body ingestion.  相似文献   
107.
108.
109.
110.
A rapid procedure for determining angiotensin II in the blood by inverse voltammetry using a TA-2 device (Tekhnoanalit Company, Tomsk) with a graphite electrode has been developed. The results of analyses using the proposed technique agree with the clinical data. The rapid analytical procedure favors optimization of cardiotropic drug therapy. __________ Translated from Khimiko-Farmatsevticheskii Zhurnal, Vol. 40, No. 12, pp. 54–56, December, 2006.  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