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   12422篇
  免费   920篇
  国内免费   35篇
耳鼻咽喉   116篇
儿科学   291篇
妇产科学   315篇
基础医学   1983篇
口腔科学   212篇
临床医学   1240篇
内科学   2327篇
皮肤病学   198篇
神经病学   1284篇
特种医学   368篇
外科学   1842篇
综合类   170篇
一般理论   8篇
预防医学   877篇
眼科学   362篇
药学   970篇
中国医学   14篇
肿瘤学   800篇
  2021年   128篇
  2020年   63篇
  2019年   114篇
  2018年   156篇
  2017年   131篇
  2016年   138篇
  2015年   203篇
  2014年   286篇
  2013年   496篇
  2012年   561篇
  2011年   645篇
  2010年   353篇
  2009年   345篇
  2008年   617篇
  2007年   643篇
  2006年   617篇
  2005年   670篇
  2004年   643篇
  2003年   586篇
  2002年   591篇
  2001年   189篇
  2000年   152篇
  1999年   163篇
  1998年   150篇
  1997年   143篇
  1996年   111篇
  1995年   111篇
  1994年   102篇
  1993年   92篇
  1992年   138篇
  1991年   134篇
  1990年   102篇
  1989年   85篇
  1988年   116篇
  1987年   103篇
  1986年   112篇
  1985年   124篇
  1984年   151篇
  1983年   116篇
  1982年   135篇
  1981年   157篇
  1980年   159篇
  1979年   127篇
  1978年   108篇
  1977年   106篇
  1976年   99篇
  1975年   119篇
  1974年   112篇
  1973年   116篇
  1972年   70篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
L D Fricker  E Herbert 《Brain research》1988,453(1-2):281-286
Several diverse species contain an enzyme with many properties in common with those of bovine carboxypeptidase E (CPE), a neuropeptide processing carboxypeptidase B-like enzyme. This enzyme has been designated EC 3.4.17.10, and is also known as enkephalin convertase and carboxypeptidase H. All tissues that are known to contain bioactive peptides also contain CPE-like enzymatic activity. In Xenopus laevis, enzyme activity is highest in the brain and pituitary, lower in the skin, and undetectable in liver and gut. In Aplysia californica, enzyme activity is highest in the atrial gland, but is also present in moderate amounts in the various neural tissue. CPE extracted from human, bovine, mouse, Xenopus, shark, and Aplysia neural tissue is substantially purified using substrate affinity chromatography and concanavalin A sepharose columns. The partially purified enzyme from all species examined possess very similar enzymatic properties. These properties include a pH optimum of 5.6, a stimulation by cobalt chloride, and an inhibition by chelating agents (1,10-phenanthroline). Arginine-derived active site-directed inhibitors show similar inhibition constants (Ki's) towards enzyme from the various species, whereas lysine-derived inhibitors are substantially less potent towards the Aplysia carboxypeptidase than towards enzyme isolated from the other species. The similar properties of the carboxypeptidase isolated from the various species suggests that a CPE-like is involved in the biosynthesis of many peptide neurotransmitters and hormones in a wide range of organisms.  相似文献   
22.
23.
24.
25.
A transoral technique for the excision of primary hypopharyngeal, posterior pharyngeal, and lateral pharyngeal wall tumors using the CO2 or KTP laser and an operating microscope is presented.  相似文献   
26.
The antinociceptive effects of morphine (5 μg) microinjected into the ventrolateral periaqueductal gray were determined using both the tail flick and the foot withdrawal responses to noxious radiant heating in lightly anesthetized rats. Intrathecal injection of appropriate antagonists was used to determine whether the antinociceptive effects of morphine were mediated byα2-noradrenergic, serotonergic, opioid, or cholinergic muscarinic receptors. The increase in the foot withdrawal response latency produced by microinjection of morphine in the ventrolateral periaqueductal gray was reversed by intrathecal injection of the cholinergic muscarinic receptor antagonist atropine, but was not affected by the a2-adrenoceptor antagonist yohimbine, the serotonergic receptor antagonist methysergide, or the opioid receptor antagonist naloxone. In contrast, the increase in the tail flick response latency produced by morphine was reduced by either yohimbine, methysergide or atropine. These results indicate that microinjection of morphine in the ventrolateral periaqueductal gray inhibits nociceptive responses to noxious heating of the tail by activating descending neuronal systems that are different from those that inhibit the nociceptive responses to noxious heating of the feet. More specifically, serotonergic, muscarinic cholinergic andα2-noradrenergic receptors appear to mediate the antinociception produced by morphine using the tail flick test. In contrast, muscarinic cholinergic, but not monoamine receptors appear to mediate the antinociceptive effects of morphine using the foot withdrawal response.  相似文献   
27.
Loprazolam (1) is a tricyclic benzodiazepine containing a new butazadiene moiety, which has not been investigated by polarography up to now. 1 is reduced in three waves at a DME over the whole pH-region. In BRP (pH 2-9) 10 electrons are consumed in this process. The first step is suitable for the determination of 1 in Loprazolam tablets containing 1 or 2 mg. These tablets are on the pharmaceutical market in several European countries. The mechanism of the electrode process will be reported in the communication XXXIV.  相似文献   
28.
Binswanger’s disease is pathologically characterized by a combination of diffuse cerebrovascular white matter lesions and lacunar infarcts in the basal ganglia and white matter. Although a blood-brain barrier (BBB) dysfunction has been implicated in the pathogenesis of these white matter (WM) lesions, few authors have addressed this problem. In the present study, we describe BBB dysfunction and its regional differences in the brains of Binswanger’s disease patients. Twelve brains from Binswanger’s disease patients (group III) were examined and compared with those from five patients with non-neurological disease (group I) and five cortical infarct patients without significant WM lesions (group II). Immunohistochemistry was performed for glial fibrillary acidic protein and vimentin as astroglial cell markers, and for immunoglobulins, complements and fibrinogen as extravasated serum protein markers. The grading scores for IgG extravasation were significantly higher in group III as compared to group I, in both the periventricular WM and the subcortical WM (P < 0.01). In group III, the scores in the periventricular WM and subcortical WM were significantly higher than in the subcortical U fibers and cerebral cortex (P < 0.01 for the periventricular WM; P < 0.001 for the subcortical WM), respectively. Clasmatodendritic astroglia, which had swollen cell bodies and large cytoplasmic vacuoles with disintegrated processes, incorporated the serum components IgG, IgM, C3d, C1q and fibrinogen, both in the periventricular WM and subcortical WM in 5 out of 12 (42%) Binswanger’s disease brains. These results indicate that WM lesions in Binswanger’s disease are accompanied by BBB dysfunction, although it remains uncertain whether BBB dysfunction is secondary to either chronic cerebral ischemia or arterial hypertension. Received: 25 April 1997 / Revised, accepted: 21 July 1997  相似文献   
29.
30.
OBJECTIVE: To examine the extent to which the public's desire for social distance from people with schizophrenia is influenced by beliefs about the disorder and stereotypes about those suffering from it. METHODS: In spring 2001, we carried out a representative survey of individuals of German nationality aged 18 years and over (n = 5025). Each subject was given a fully structured interview that began with the presentation of a vignette. RESULTS: Both labelling and beliefs about the disorder's causes and prognosis, as well as the perception that those suffering from it are unpredictable and dangerous, had an impact on the public's desire for social distance. However, the latter proved to be more important. As expected, respondents who identified the disorder depicted in the vignette as mental illness, those who blamed the individual for its development, and those who anticipated a poor prognosis expressed a stronger desire for social distance. Endorsing biological factors as a cause was also associated with increased social distance. CONCLUSIONS: Our findings have important implications for interventions aimed at reducing stigma and discrimination related to schizophrenia. Targeting the stereotype of unpredictability and dangerousness appears to be particularly important.  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