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   3210293篇
  免费   257354篇
  国内免费   9325篇
耳鼻咽喉   45263篇
儿科学   100870篇
妇产科学   86436篇
基础医学   446439篇
口腔科学   91987篇
临床医学   293504篇
内科学   634718篇
皮肤病学   69684篇
神经病学   269596篇
特种医学   129000篇
外国民族医学   1111篇
外科学   489520篇
综合类   76919篇
现状与发展   3篇
一般理论   1298篇
预防医学   262257篇
眼科学   73600篇
药学   233624篇
  9篇
中国医学   5771篇
肿瘤学   165363篇
  2018年   32853篇
  2016年   29196篇
  2015年   32879篇
  2014年   46829篇
  2013年   71058篇
  2012年   92211篇
  2011年   98204篇
  2010年   59250篇
  2009年   57113篇
  2008年   92730篇
  2007年   98769篇
  2006年   99879篇
  2005年   97307篇
  2004年   93382篇
  2003年   90470篇
  2002年   88092篇
  2001年   147391篇
  2000年   152377篇
  1999年   128300篇
  1998年   38624篇
  1997年   34849篇
  1996年   35159篇
  1995年   34630篇
  1994年   32463篇
  1993年   30393篇
  1992年   104890篇
  1991年   101663篇
  1990年   98086篇
  1989年   93970篇
  1988年   87445篇
  1987年   86239篇
  1986年   81617篇
  1985年   78438篇
  1984年   59779篇
  1983年   50941篇
  1982年   31500篇
  1981年   28334篇
  1980年   26664篇
  1979年   55682篇
  1978年   39816篇
  1977年   33539篇
  1976年   31337篇
  1975年   32896篇
  1974年   40085篇
  1973年   38179篇
  1972年   35709篇
  1971年   33085篇
  1970年   30918篇
  1969年   28787篇
  1968年   26482篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Esophageal pH monitoring is the accepted standard for the investigation of gastroesophageal reflux (GER) in adults. A postal questionnaire was sent to 912 United Kingdom paediatric physicians & surgeons. Five hundred forty-seven (61%) replied, with 124 (22.7%) currently using the technique, mostly in conjunction with barium swallow and/or esophagoscopy. The use of pH monitoring to quantify GER was also accepted in principal as being the best determinant of reflux by a further 186 (34%), but as yet was unavailable in their hospitals. Pediatricians were also questioned as to their management of children with GER. The majority were treated medically with a variety of antireflux medication, with only 237 (42%) referring cases for surgery.  相似文献   
992.
993.
1. The frequent occurrence of hypothalamo-pituitary dysfunction in patients with eating disorders as well as prior reports that nutritional and endocrine status influence pituitary morphology, led us to hypothesize that pituitary size and shape may be altered in patients with eating disorders. 2. Magnetic resonance imaging (MRI) does not use ionizing radiation and is currently one of the most feasible modalities available to study the pituitary gland in vivo. Using MRI, we have previously reported in a preliminary study that female patients with eating disorders had significantly smaller pituitary glands than controls. In addition MRI excluded any pituitary mass lesions. 3. In this report, we confirm our previous MRI findings and provide further evidence of pituitary abnormalities in an expanded sample of eating disorder patients. Preliminary data on pituitary volume estimates from MRI scans are provided for a subset of patients and controls.  相似文献   
994.
1. Rhesus monkeys were equipped with a novel intracerebroventricular (i.c.v.) cannula system and trained to respond under operant schedules of food presentation or termination of stimuli associated with the delivery of shock (escape). 2. CRH decreased food-maintained behavior in a dose-related manner over the range of (0.3-10 micrograms/kg) but did not affect escape responding, demonstrating a selective effect on food-maintained responding. 3. This selective effect was related to the tendency for responding to stop after delivery of a food pellet when higher doses of CRH were given, consistent with the notion that a conditioned aversion to food was established in the presence of CRH. 4. This may suggest that in hyperaroused clinical states such as depression and anorexia nervosa, focus is shifted away from appetitive tasks as a result of increased levels of CRH.  相似文献   
995.
A girl of 14 year is presented with a distal spinal muscular atrophy (SMA) with autosomal recessive inheritance. The technical findings are in agreement with the diagnosis. Light microscopical examination of sural nerve biopsy, including teased fiber studies and morphometry, showed no abnormalities. Electron microscopical investigation however demonstrated axonal pathology. The question arises if distal SMA is a distal axonopathy mainly of motor nerves, but to some extent also of sensory nerves.  相似文献   
996.
Atheromatous lesions of the proximal vertebral artery and the subclavian artery may lead to ischaemic manifestations, occasionally with severe consequences in the vertebro-basilar territory. These transient ischaemic attacks are most often caused by haemodynamic insufficiency rather than thrombo-embolic complications addressed by anticoagulant and antiaggregant treatments. In this study, 8 cases of vertebro-basilar ischaemia (VBI), secondary to subclavian and proximal vertebral artery lesions, are reported. Surgical techniques, subclavian-to-subclavian artery by-pass (5 cases) and vertebral to common carotid artery transposition (3 cases) are described with their respective results. Through a review of the literature, the various operative modalities are discussed in the different pathological conditions of the proximal extracranial vertebro-basilar disease. It appears that the subclavian to subclavian artery by-pass as well as the vertebral-to-common carotid artery transposition are safe surgical procedures with strikingly low morbidity and mortality rates. The widely achieved relief of the ischaemic episodes, undoubtedly makes this surgery an alternative to medical treatment.  相似文献   
997.
998.
999.
The Flinders Sensitive Line (FSL) of rats has been selectively bred to have increased sensitivity to cholinergic agonists. However, these rats exhibit altered responsiveness to a number of noncholinergic agents, such as apomorphine, buspirone and ethanol. This study compared the FSL and control Flinders Resistant Line (FRL) rats in terms of their hyperthermic response to the phencyclidine (PCP) receptor agonist, MK-801 (0.2 mg/kg SC) and their MK-801 binding characteristics. We have found that FSL rats react with a delayed hyperthermia, having a significantly lower hyperthermia for the first 120 min of observation. Thereafter the response does not differ in FSL and FRL rats. Both groups had similar affinities and numbers of [3H]MK-801 binding sites in the hippocampus/cerebral cortex. Pretreatment with scopolamine (1 mg/kg SC) failed to affect MK-801-induced hyperthermia in either line of rats. These findings suggest that selective breeding of FSL rats attenuated the secondary mechanisms involved in the PCP receptor-mediated hyperthermic response. However, by itself cholinergic supersensitivity does not appear to be a major factor in the blunted responsiveness of FSL rats to MK-801.  相似文献   
1000.
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