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   1698303篇
  免费   123888篇
  国内免费   3803篇
耳鼻咽喉   21776篇
儿科学   55672篇
妇产科学   46192篇
基础医学   241784篇
口腔科学   48761篇
临床医学   151539篇
内科学   334269篇
皮肤病学   38710篇
神经病学   131480篇
特种医学   63990篇
外国民族医学   242篇
外科学   257542篇
综合类   38960篇
现状与发展   4篇
一般理论   532篇
预防医学   124356篇
眼科学   40257篇
药学   123900篇
  7篇
中国医学   4489篇
肿瘤学   101532篇
  2021年   12954篇
  2019年   13602篇
  2018年   20049篇
  2017年   15295篇
  2016年   16698篇
  2015年   19042篇
  2014年   26325篇
  2013年   38112篇
  2012年   52985篇
  2011年   55642篇
  2010年   32903篇
  2009年   30823篇
  2008年   51722篇
  2007年   54982篇
  2006年   55435篇
  2005年   52715篇
  2004年   50904篇
  2003年   48273篇
  2002年   46512篇
  2001年   91801篇
  2000年   93620篇
  1999年   76976篇
  1998年   19733篇
  1997年   17279篇
  1996年   17410篇
  1995年   16760篇
  1994年   15304篇
  1993年   14090篇
  1992年   57391篇
  1991年   55281篇
  1990年   52982篇
  1989年   50751篇
  1988年   46141篇
  1987年   44940篇
  1986年   42230篇
  1985年   39996篇
  1984年   29355篇
  1983年   24918篇
  1982年   13906篇
  1979年   25534篇
  1978年   17580篇
  1977年   14914篇
  1976年   13877篇
  1975年   14563篇
  1974年   17635篇
  1973年   16950篇
  1972年   15679篇
  1971年   14457篇
  1970年   13435篇
  1969年   12521篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
102.
OBJECTIVES: Pseudotumour cerebri has been previously recognized as a neurological side effect of combined oral contraceptives but has not been diagnosed with a delay of 3 years after initiation of combined oral contraceptives. CASE REPORT: A 19-year-old obese woman developed visual impairment and headache, 4 months after starting combined oral contraceptives. Three years later symptoms deteriorated and she presented with prominent tendon-jerks and congested optical-discs. Normal CSF drained with high pressure from the spinal tap. Pseudotumour cerebri was diagnosed. Headache and visual impairment resolved within 3 weeks after discontinuation of combined oral contraceptives. CONCLUSIONS: Combined oral contraceptives-induced pseudotumour cerebri may remain undetected for years. Young, obese women with visual impairment and headache under combined oral contraceptives should undergo immediate neurological and ophthalmological investigation.  相似文献   
103.
In order to assess the state and pathology of the woman's pelvis minor, a number of methods are commonly used among practitioners, encompassing clinical exploration, radiology, MRN, urodynamics, endoscopy and echography.

Echography has been poorly used in clinical pelvic exploration and its reliability is actually a matter of controversy 1. However, echographic surveys can provide us with valuable gynecological data on the state and pathologies of the soft pelvis, within the genital regions or even going beyond them, i.e. the rectal channel, bladder, urethra, anus, vascular plexuses, and all of their supporting tissues.

At our research unit, we have been employing Transvaginal Ultrasound echography (TVU) for a long time in conjunction with other pelvis-focused methods in order to study different kinds of pelvic alterations. TVU has proven to be friendly to use, fast, harmless and inexpensive, allowing serial explorations and producing high-quality dynamic images (loop-cinema, video-tape). Furthermore, this method is fairly aseptic in that the occurrence of faeces in the rectal ampolla is not a nuisance but a bonus in tracking the contours of the rectum walls and other topographical features which would be otherwise difficult to survey.

A complete pelvic floor TVU may add no longer than 5-8 minutes to a routine gynecological examination, can be implemented by the general gynecologist and generates data that can be further studied by the appropriate specialist for a more insightful evaluation 2.  相似文献   
104.
A 41-year-old Chinese lady had a Gr?fenberg ring in utero for 15 years. During that period of time, she had one normal vaginal delivery a year after insertion, followed by an ectopic pregnancy 12 years later. We discuss the possible mechanism of action of the Gr?fenberg ring and sequelae of its prolonged presence in the uterus.  相似文献   
105.
Postpartum fatigue is a normal condition that most women experience. Breastfeeding is often associated in women's minds as contributing to the feeling of overall perceived fatigue, and many women indicate that they have ceased breastfeeding because of fatigue. However, the relationship between feeding choice and perceived fatigue has never been established. Two hundred and fifty-three women participated in a study examining whether perceived fatigue differed for bottle-feeding and breastfeeding women at 3 different times during the postpartum period (2-4 days, 6 weeks, and 12 weeks postpartum). Results showed no significant differences for these 2 groups, suggesting that perceived fatigue during the postpartum period is not dependent on feeding choice. Additional analyses examining other variables with a potential effect were nonsignificant. Because perceived physical fatigue does not appear to be dependent on feeding choice, women should be prepared for the feeling of perceived fatigue during the postpartum period while at the same time be reassured that feeding choice is not correlated.  相似文献   
106.
107.
BACKGROUND: In the central nervous system, several neuropeptides are believed to be involved in the pathophysiology of Alzheimer's disease (AD). Indeed, previous studies have documented that glucagon-like peptide 1 (GLP-1) possesses neurotropic properties and can reduce amyloid-beta peptide levels in the brain in vivo. Moreover, the concentrations of neuropeptide Y (NPY) seem to be altered in the cerebrospinal fluid of patients with AD and in subjects with major depression. Finally, among the modifications induced by aging, a dysregulation of the ghrelin-growth hormone (GH) system has been reported. METHODS: We investigated the plasma concentrations of these neuropeptides in 14 subjects with AD. Data obtained from these patients were compared with data from an age- and weight-matched healthy group. RESULTS: No significant differences were found between the two groups in relation to plasma levels of GLP-1, NPY, ghrelin and GH. Peripheral NPY concentrations were positively correlated with ghrelin levels in both groups, and with plasma GLP-1 concentration only in controls. CONCLUSION: On the basis of our results, peripheral levels of these neuropeptides seem not to serve as biochemical markers of AD.  相似文献   
108.
109.
110.
S Raam  D M Vrabel 《Clinical chemistry》1988,34(10):2053-2057
We present evidence to show that monoclonal antibodies to estrogen receptors (ER) in solid phase recognize the secondary estrogen binding sites with moderate to low affinity for estradiol (E2). An excellent quantitative agreement was found in five cytosols between the ER values obtained by the enzyme immunoassay (ER-EIA) and the amount of secondary estrogen binding sites measured by the assay involving dextran-coated charcoal (Clin Chem 1986;32:1496). The immunoreactive protein recognized by the antibody-coated beads, when allowed to react with ER(+) cytosols, is shown to bind [3H]estradiol only when the ligand concentration exceeds 8 nmol/L. Further biochemical and functional characterization of the immunoreactive protein is required to establish similarities/dissimilarities between this protein, high-affinity Type I ER sites, and the secondary sites such as Type II sites.  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