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   1800890篇
  免费   132986篇
  国内免费   3002篇
耳鼻咽喉   26078篇
儿科学   55517篇
妇产科学   49841篇
基础医学   257465篇
口腔科学   51975篇
临床医学   159283篇
内科学   340835篇
皮肤病学   38740篇
神经病学   140926篇
特种医学   71880篇
外国民族医学   370篇
外科学   277558篇
综合类   43364篇
现状与发展   3篇
一般理论   510篇
预防医学   133531篇
眼科学   42442篇
药学   140645篇
  7篇
中国医学   4074篇
肿瘤学   101834篇
  2018年   17339篇
  2016年   15458篇
  2015年   17604篇
  2014年   24584篇
  2013年   36549篇
  2012年   49675篇
  2011年   52395篇
  2010年   30680篇
  2009年   28826篇
  2008年   48905篇
  2007年   52711篇
  2006年   53149篇
  2005年   51308篇
  2004年   49720篇
  2003年   47725篇
  2002年   46126篇
  2001年   86896篇
  2000年   89004篇
  1999年   74780篇
  1998年   20081篇
  1997年   18059篇
  1996年   17988篇
  1995年   16922篇
  1994年   15757篇
  1993年   14921篇
  1992年   59318篇
  1991年   57522篇
  1990年   56547篇
  1989年   54589篇
  1988年   50151篇
  1987年   49089篇
  1986年   46442篇
  1985年   44246篇
  1984年   32981篇
  1983年   28163篇
  1982年   16563篇
  1981年   14804篇
  1979年   31524篇
  1978年   21973篇
  1977年   19154篇
  1976年   17058篇
  1975年   19019篇
  1974年   22887篇
  1973年   22001篇
  1972年   21012篇
  1971年   19635篇
  1970年   18418篇
  1969年   17890篇
  1968年   16008篇
  1967年   14546篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
941.
Ranitidine influences the uptake of oral midazolam.   总被引:1,自引:0,他引:1       下载免费PDF全文
In a randomised crossover study in volunteers plasma midazolam levels were estimated for 24 h following 15 mg by mouth, either preceded by no medication or following 24 h therapy with ranitidine. Administration of the H2-receptor blocker significantly increased bioavailability of the benzodiazepine and resulted in higher plasma levels for the first 6 h after taking midazolam. This was accompanied by a greater soporific effect.  相似文献   
942.
Neurogenic bladder dysfunction, characterized by hesitancy, need to strain, decreased stream, and increased duration of urination, developed in 104 (63%) of 166 employees working in the manufacture of polyurethane foam. Highest rates of illness (69%) occurred in production workers, and no illness occurred in office or warehouse workers. Onset of the epidemic coincided with introduction of a catalyst, dimethylaminopropionitrile (DMAPN), and monthly case incidence rates increased as DMAPN use increased. Outbreak ceased abruptly when DMAPN use was stopped. Of eight patients who underwent neurourologic testing during recovery, seven lacked either detrusor reflex or normal sensation of bladder filling; seven had a subclinical sensory abnormality; three had prolonged sacral-evoked responses; and two of these three had limb motor neuropathies. Dimethylaminopropionitrile is unique among known neurotoxins in producing urinary symptoms more frequently than limb nerve symptoms.  相似文献   
943.
A crossover double-blind controlled trial was performed on 36 patients with rheumatoid arthritis to assess the necessity for serum salicylate monitoring in determining optimal dosage. There was no clinically or statistically significant increase in the clinical improvement of patients associated with serum monitoring but potentially toxic serum levels occurred without tinnitus when serum monitoring was not used.  相似文献   
944.
Although many studies as well as conventional wisdom suggest that increases in income result in improved diet and nutritional status in rural areas of developing countries, several recent studies have failed to demonstrate such a relationship. In this paper the relationships between material wealth and income and dietary strategies are examined for an agricultural community in rural Mexico. A superficial examination focusing on summary indices of dietary adequacy frequently cited in the literature and indices of wealth and income demonstrates a positive relationship between them in this community. However, an examination of the same data emphasizing alternative dietary strategies to achieve nutritional adequacy shows a more complex picture. Increasing income is associated with consumption of purchased foods especially foods of animal origin, and is not associated with the consumption of staple foods produced within the household. Diets dependent on purchased foods do not necessarily meet nutritional needs more adequately than diets which rely on agricultural products and gathered foods. Among the implications of this research are a need for a method of analysis which focuses on alternative nutritional strategies available in particular settings, and a need to reassess the relative importance of income generating activities and subsistence agriculture in areas undergoing agricultural change.  相似文献   
945.
946.
947.
Seventy seven antral biopsies were collected from patients attending endoscopy clinic at King Khalid University Hospital, Riyadh, Saudi Arabia during a period of six months between December 1988 to May 1989. Of these 69 (89.6%) showed chronic gastritis as well as Helicobacter-like organisms (HLOs) in the biopsy specimens while 63 (81.8%) of biopsies grew Helicobacter pylori on culture. These findings indicate a good correlation between the histological diagnosis of chronic gastritis and isolation of H. pylori on culture.  相似文献   
948.
To measure prefrontal and subcortical activity during a cognitive task, we examined 19 newly diagnosed schizophrenics and patients with schizophreniform psychosis. Seven healthy volunteers served as controls. The patients were drug naive or had received neuroleptics for a few days only. Cerebral blood flow distribution was depicted by single photon emission computed tomography at rest and during activation with the Wisconsin Card Sorting Test. A significant relative activation deficit in the left inferior-prefrontal region was revealed during the Wisconsin Card Sorting Test in the patient group. Furthermore, the patients had impaired striatal suppression on the left side during the cognitive task. The test performance was significantly impaired in the patients. The inability to reduce striatal activity may be due to a lack of corticostriatal feedback during prefrontal activation.  相似文献   
949.
Blood bank staff, 8 out of 25 (32%) have been exposed to hepatitis B virus (HBV) and the prevalence of HBV markers in blood bank employees handling high risk subjects show hepatitis B surface antigen (n = 1), hepatitis B surface antibody (n = 7), hepatitis B core antibody (n = 6) and combined hepatitis B surface antibody and hepatitis B core antibody (n = 6) seropositivity but all are negative to human immunodeficiency virus (HIV). Serum alanine aminotransferase was raised in the employees than normal subjects and it is suggestive of sub-clinical hepatitis. The employees of blood bank should be trained for proper handling of test materials and must be periodically monitored for HBV and HIV. Immunisation for HBV is mandatory only for the employees of transfusion centre which handles high risk subjects.  相似文献   
950.
Leukotriene C4 (LTC4) production in the guinea pig spinal cord following compression injury was determined by radioimmunoassay, in the same way thromboxane B2 (TXB2), a stable metabolite of thromboxane A2 (TXA2), was also measured. When the spinal cords were compressed under a 20 gram weight for 10 minutes, LTC4 levels reached peak values (2.2 +/- 0.4 pmol/g cord) 10 minutes after release, then gradually decreased until being undetectable 60 minutes later. TXB2 levels reached peak values (146.8 +/- 6.2 pmol/g cord) 5 minutes after the release from compression, the TXB2 level then gradually decreased, but remained at about 1/2 of the peak level even 60 minutes after the release. When the spinal cords were compressed with various weights, TXB2 production depended on the degree of compression, while LTC4 production was not affected by the compression injury. The LTC4 production confirmed in the injured spinal cords is suggestive of its relation to secondary disorders after spinal cord injury, spinal edema, in particular.  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