全文获取类型
收费全文 | 2692779篇 |
免费 | 193747篇 |
国内免费 | 7831篇 |
专业分类
耳鼻咽喉 | 35736篇 |
儿科学 | 87982篇 |
妇产科学 | 74304篇 |
基础医学 | 379306篇 |
口腔科学 | 73447篇 |
临床医学 | 241323篇 |
内科学 | 538546篇 |
皮肤病学 | 65401篇 |
神经病学 | 222669篇 |
特种医学 | 102505篇 |
外国民族医学 | 737篇 |
外科学 | 398798篇 |
综合类 | 50965篇 |
现状与发展 | 5篇 |
一般理论 | 987篇 |
预防医学 | 210262篇 |
眼科学 | 59583篇 |
药学 | 196399篇 |
8篇 | |
中国医学 | 5739篇 |
肿瘤学 | 149655篇 |
出版年
2021年 | 22101篇 |
2019年 | 22983篇 |
2018年 | 32829篇 |
2017年 | 24845篇 |
2016年 | 28427篇 |
2015年 | 31927篇 |
2014年 | 43336篇 |
2013年 | 64586篇 |
2012年 | 87245篇 |
2011年 | 92071篇 |
2010年 | 54846篇 |
2009年 | 51957篇 |
2008年 | 84975篇 |
2007年 | 90139篇 |
2006年 | 91546篇 |
2005年 | 87374篇 |
2004年 | 83973篇 |
2003年 | 80868篇 |
2002年 | 77889篇 |
2001年 | 130472篇 |
2000年 | 133604篇 |
1999年 | 112345篇 |
1998年 | 31722篇 |
1997年 | 28210篇 |
1996年 | 28504篇 |
1995年 | 27628篇 |
1994年 | 25284篇 |
1993年 | 23603篇 |
1992年 | 86343篇 |
1991年 | 82672篇 |
1990年 | 79901篇 |
1989年 | 76998篇 |
1988年 | 70403篇 |
1987年 | 68902篇 |
1986年 | 64481篇 |
1985年 | 61381篇 |
1984年 | 45612篇 |
1983年 | 38494篇 |
1982年 | 22781篇 |
1981年 | 20266篇 |
1979年 | 39757篇 |
1978年 | 27991篇 |
1977年 | 23817篇 |
1976年 | 22024篇 |
1975年 | 23409篇 |
1974年 | 27596篇 |
1973年 | 26235篇 |
1972年 | 24568篇 |
1971年 | 22729篇 |
1970年 | 20923篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
W. S. L. Stebbings M. J. G. Farthing J. R. Puddefoot Elizabeth Anderson G. P. Vinson J. M. A. Northover R. F. M. Wood 《Journal of cancer research and clinical oncology》1988,114(2):208-211
Summary To evaluate the potential effect of androgens on the development and growth of human colorectal adenomas, the prevalence and concentration of cytosolic androgen receptors (AR) were analysed in 26 adenomas and 19 samples of normal colonic mucosa by a hybrid ligand receptor-binding assay. AR were detected in 7 of the adenomas (26.9%), and in 6 of the normal mucosa samples (31.6%). In the adenomas, AR levels demonstrated were low, ranging from 6 to 31 fmol/mg cytosol protein, and dissociation constants (Kds) ranged from 0.17–2.7x10-9
M. Of 13 adenomas excised from men, 6 (46%) had positive receptor activity, whereas only 1 of 13 (7.7%) from women was positive (P=0.03, Fisher's exact test). There was no correlation between AR titre and patient age, or between adenoma size and histological type or degree of dysplasia. In normal mucosa, AR levels ranged from 7 to 33 fmol/mg and Kds ranges from 0.24–3.1x10-9
M. There was no significant difference between either AR prevalence or levels in the adenomas and normal mucosa. The sex difference was exclusive to the adenoma. Endogenous androgen may play a role in adenoma development early in the promotional process. 相似文献
992.
993.
Cytokines play a part in the control of cellular growth, differentiation and development. Given such pleiotropic activities, it is not unexpected that the expression of the cytokines is tightly regulated. When cytokine-mediated processes are altered by mutation and/or overexpression of some cytokine or cytokine receptor genes, oncogenic transformation can occur. Oncogenes which derive their transforming potential through this mechanism include sis, which represents the activated form of the platelet-derived growth factor B chain, hst1/K-fgflint-2, which share appreciable homology with the gene family of fibroblast growth factors, fms, which is related to the cell surface receptor for macrophage-colony stimulating factor, and erbB-1, which encodes a truncated form of the epidermal growth factor receptor. Cytokine treatment has resulted in modulation of aberrant oncogene activity in some model systems. 相似文献
994.
R M Hodes B Teferedegne 《International journal of leprosy and other mycobacterial diseases : official organ of the International Leprosy Association》1988,56(2):228-230
It has long been noted that tetanus is rare in leprosy patients. Five cases of tetanus are reported in leprosy patients in Addis Ababa, Ethiopia. Although natural immunity to tetanus occurs and this appears to be higher in leprosy patients than in the general population, it is not completely protective. Further research on the relationship between tetanus and leprosy is indicated. Although firm epidemiologic data are lacking, it is prudent to give leprosy patients at least one dose of tetanus toxoid. 相似文献
995.
Using indirect immunohistochemistry and an antiserum raised against rat corticotrophin-releasing factor (CRF) we have outlined an asymmetric network of cells and varicose fibers in sheep adrenal cortex. This network was not associated with the larger splanchnic nerves, but was occasionally found in small bundles or with blood vessels; in most instances fibers were found weaving independently through cortical parenchyma. A plexus of fibers was found in the zona reticularis, with a few fibers ramifying into adjacent medulla. Uni or bipolar cells were found throughout the cortex, with the greatest frequency at the corticomedullary junction; a multipolar-type cell was also found in this area. Staining of varicose structures and most cells was abolished by incubation with excess rat CRF 1-41, but not by ovine CRF or a range of other peptides. Though the immunoreactive species has not as yet been identified, it may thus share homology with sequences present in rat but not ovine CRF. 相似文献
996.
M R Montminy 《Nippon Naibunpi Gakkai zasshi》1988,64(12):1233-1235
997.
In an attempt to identify a cause for the alteration in breathing pattern seen when conventional respiratory apparatus is applied to the face, we have studied the effects of causing the subject to focus attention on breathing by counting breaths in threes for 5 min. We used the respiratory inductance plethysmograph in 18 naive subjects who were unaware that their breathing was being measured. In the control periods, distraction was provided by a recorded story played through head-phones. The experiment was repeated with the rim of a facemask applied to the face. Focusing attention on breathing caused a prolongation of inspiration at a constant mean inspiratory flow, and lengthening of expiration. Tidal volume but not ventilation was increased. The facemask rim caused no significant change. It is concluded that conscious awareness of breathing could account for a major part of the effect of conventional respiratory apparatus. 相似文献
998.
999.
The aim of the study was to evaluate the importance of atrial synchronism for pacing therapy of patients with mixed carotid sinus syndrome. On 23 patients (21 m, 2 f; mean age 69 +/- 8 years) affected by symptomatic mixed carotid sinus syndrome we performed: 1) the study of ventriculo-atrial conduction, 2) the evaluation of pacemaker effect and 3) the carotid sinus massage in standing position during VVI and DVI temporary pacing. All patients received a permanent DVI pacemaker and then underwent a two-month period single-blind, randomized, cross-over study on DVI vs VVI mode. During DVI period, no syncope occurred in any patients, minor symptoms persisted in 11 (48%) of them; during VVI period syncopes recurred in 3 patients, symptoms requiring the withdrawal of VVI pacing and premature DVI reprogramming in 8, minor symptoms were observed in 17 (74%). A comparison between 14 patients who preferred DVI period (Group A) and the remaining 9 patients who had no preference for DVI and VVI period (Group B) revealed that Group A patients had a greater pacemaker effect (-34 +/- 16 mmHg vs -16 +/- 14 mmHg; p less than 0.02) and a higher prevalence of ventriculo-atrial conduction (78% vs 44%; p = 0.1), while the entity of the systolic pressure fall caused by carotid sinus massage was similar in the two groups both during VVI mode (Group A -51 +/- 16 mmHg vs Group B -56 +/- 27 mmHg) and DVI mode (Group A -38 +/- 17 mmHg vs Group B -45 +/- 17 mmHg).(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献