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   2359407篇
  免费   175786篇
  国内免费   5081篇
耳鼻咽喉   32305篇
儿科学   74654篇
妇产科学   65665篇
基础医学   337063篇
口腔科学   69544篇
临床医学   210222篇
内科学   455246篇
皮肤病学   51908篇
神经病学   184692篇
特种医学   90545篇
外国民族医学   406篇
外科学   360889篇
综合类   58569篇
现状与发展   6篇
一般理论   752篇
预防医学   178458篇
眼科学   56601篇
药学   174600篇
  8篇
中国医学   5573篇
肿瘤学   132568篇
  2018年   25107篇
  2017年   19293篇
  2016年   21352篇
  2015年   24496篇
  2014年   34379篇
  2013年   50803篇
  2012年   69704篇
  2011年   73451篇
  2010年   43312篇
  2009年   40537篇
  2008年   68606篇
  2007年   73487篇
  2006年   73779篇
  2005年   71067篇
  2004年   68911篇
  2003年   65770篇
  2002年   63505篇
  2001年   114630篇
  2000年   117240篇
  1999年   97684篇
  1998年   26766篇
  1997年   23702篇
  1996年   23623篇
  1995年   22588篇
  1994年   20968篇
  1993年   19557篇
  1992年   76299篇
  1991年   73959篇
  1990年   71613篇
  1989年   68926篇
  1988年   63503篇
  1987年   62176篇
  1986年   58689篇
  1985年   56128篇
  1984年   42057篇
  1983年   35865篇
  1982年   21050篇
  1981年   19036篇
  1979年   39021篇
  1978年   27435篇
  1977年   23255篇
  1976年   21567篇
  1975年   23015篇
  1974年   28114篇
  1973年   27099篇
  1972年   25502篇
  1971年   23678篇
  1970年   22247篇
  1969年   21052篇
  1968年   19414篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
131.
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   
132.
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   
133.
134.
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   
135.
136.
In this study, we examine the prevalence of finding isolated tumor cells (ITCs) in negative lymph nodes of endometrial cancer patients using immunohistochemistry. Seventy-six endometrial cancer patients with lymph nodes histologically negative for metastatic disease were examined. Nodal tissue sections were stained with anticytokeratin antibodies AE-1 and CAM 5.2. Nodes with single or groups of cells (two to four cells) < or =0.2 mm and showing cytokeratin reactivity were positive for ITCs. Findings were compared to features of the primary tumor and patient outcome. ITCs were present in 31 of 1712 lymph nodes. Fifteen (19.7%) patients had ITC-positive nodes. ITCs involved only pelvic nodes in nine cases, only para-aortic nodes in five cases, and pelvic and para-aortic in one case. Tumor in adnexa was the only pathologic feature associated with nodal ITCs (P= 0.0485). All 15 patients with nodal ITCs were alive at follow-up. One (6.7%) patient suffered recurrent disease but was alive at last encounter. Disease recurred in 5 (8.8%) of 57 patients without nodal ITCs. Two are alive without disease, two alive with disease, and one died from her cancer. In summary, a significant proportion of endometrial cancer patients have ITCs detected by immunohistochemistry in histologically negative regional lymph nodes.  相似文献   
137.
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   
138.
139.
140.
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