全文获取类型
收费全文 | 1748954篇 |
免费 | 120795篇 |
国内免费 | 4707篇 |
专业分类
耳鼻咽喉 | 22384篇 |
儿科学 | 57060篇 |
妇产科学 | 46446篇 |
基础医学 | 268358篇 |
口腔科学 | 46085篇 |
临床医学 | 167243篇 |
内科学 | 330830篇 |
皮肤病学 | 35855篇 |
神经病学 | 138271篇 |
特种医学 | 63942篇 |
外国民族医学 | 418篇 |
外科学 | 246339篇 |
综合类 | 35313篇 |
现状与发展 | 3篇 |
一般理论 | 551篇 |
预防医学 | 144805篇 |
眼科学 | 38850篇 |
药学 | 130416篇 |
7篇 | |
中国医学 | 4033篇 |
肿瘤学 | 97247篇 |
出版年
2021年 | 13912篇 |
2019年 | 14521篇 |
2018年 | 20494篇 |
2017年 | 15312篇 |
2016年 | 16907篇 |
2015年 | 19219篇 |
2014年 | 26280篇 |
2013年 | 40252篇 |
2012年 | 56210篇 |
2011年 | 60243篇 |
2010年 | 34935篇 |
2009年 | 31814篇 |
2008年 | 54961篇 |
2007年 | 58747篇 |
2006年 | 58409篇 |
2005年 | 56205篇 |
2004年 | 53993篇 |
2003年 | 51468篇 |
2002年 | 49854篇 |
2001年 | 77196篇 |
2000年 | 79221篇 |
1999年 | 66248篇 |
1998年 | 18681篇 |
1997年 | 16628篇 |
1996年 | 16476篇 |
1995年 | 15656篇 |
1994年 | 14487篇 |
1992年 | 52450篇 |
1991年 | 52663篇 |
1990年 | 51495篇 |
1989年 | 49277篇 |
1988年 | 45484篇 |
1987年 | 44642篇 |
1986年 | 42316篇 |
1985年 | 40429篇 |
1984年 | 30347篇 |
1983年 | 25842篇 |
1982年 | 15019篇 |
1979年 | 27910篇 |
1978年 | 19875篇 |
1977年 | 16170篇 |
1976年 | 16241篇 |
1975年 | 17467篇 |
1974年 | 20895篇 |
1973年 | 20241篇 |
1972年 | 18746篇 |
1971年 | 17678篇 |
1970年 | 16379篇 |
1969年 | 14965篇 |
1968年 | 14269篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
Conclusions Limitation of this analysis is participation of limited centers. Though all the regions of the country are represented total
number of procedures reported are less. Isolated CABG is commonest procedure performed in 2004. Congenital surgical procedures
are more than the valvular heart disease procedure. For appropriate categorization we need standard nomenclature for various
congenital surgical procedures. 相似文献
92.
93.
Angiotensin Converting Enzyme Inhibitors: Animal Experiments Suggest a New Pharmacological Treatment for Alcohol Abuse in Humans 总被引:1,自引:0,他引:1
G. Spinosa MSc E. Perlanski Dipl Tech. F. H. H. Leenen MD R. B. Stewart MSc L. A. Grupp DSc 《Alcoholism, clinical and experimental research》1988,12(1):65-70
The prevalence of heavy alcohol consumption is a major problem of increasing proportions throughout the world. Although alcohol sensitizing drugs and more recently serotonin uptake inhibitors are drug interventions with some following, their long term beneficial consequences have yet to be demonstrated. In recent years, we have demonstrated that manipulating activity in the renin-angiotensin system will dramatically alter voluntary alcohol consumption in rats. Based on these findings, the present study evaluated the ability of a class of drugs known as the angiotensin converting enzyme inhibitors to reduce voluntary alcohol drinking in laboratory animals. These drugs prevent the conversion of angiotensin I to angiotensin II. They have been licensed for use in Europe and North America and are indicated in the treatment of hypertension. Our experiments showed that both captopril (Capoten, Squibb) and enalapril (Vasotec, Merck Sharpe & Dohme) can reduce alcohol drinking in both normotensive and hypertensive animals regardless of whether the pattern of intake is in a bout or of a less exaggerated nature. Furthermore, this change in alcohol intake can occur without concomitant changes in blood pressure, plasma renin activity, overall fluid balance, or the distribution and metabolism of alcohol. Taken together these findings suggest that the angiotensin converting enzyme inhibitors should be evaluated in a clinical setting for they may prove to be a useful new treatment or treatment adjunct for alcohol abuse in humans. 相似文献
94.
A mechanistic QSAR study on N-nitrosamines (NA) was performed with the aid of the semiempirical MINDO/3 method. Both the chemical reactivity and the transport in biological medium were taken into account. The parent NA molecules and their first reaction intermediates in the metabolic activation pathway were examined for possible determinants of the relative carcinogenic potency. The correlations found support the previous suggestions concerning the metabolic C alpha radical hydroxylation of NA. The role of transport properties in the early stage of NA biotransformation was also demonstrated. 相似文献
95.
96.
97.
98.
C. R. Irwin T. Myrillas M. Smyth J. Doogan C. Rice S. L. Schor 《Journal of oral pathology & medicine》1998,27(6):255-259
Fibroblasts incorporated within collagen gels induce a cell-mediated contraction of the gel to form a three-dimensional, tissue-like structure by a mechanism thought to mimic wound contraction in vivo . In this study a gel contraction model was used to investigate the ability of fibroblasts derived from adult gingiva, adult skin and fetal skin to organise a collagen matrix. In addition the effects of interleukin-1β (IL-1β) on the contraction process was also investigated. Over the concentration range 5-50 U/ml, IL-1β induced a statistically significant inhibition of gel contraction in all fibroblast cell types ( P <0.05), although fetal fibroblasts appeared least responsive and gingival fibroblasts most responsive to the inhibitory effects of this cytokine. Comparison of gel contraction by the different fibroblast strains indicated that fetal and gingival fibroblasts shared similar contraction kinetics. For the adult skin fibroblasts, three of five strains studied showed significantly diminished levels of gel contraction compared to fetal and gingival cells. This apparent difference in fibroblast phenotype may, at least in part, explain the fetal-like wound healing pattern seen in the oral mucosa. 相似文献
99.
J Grogan B H Nowicki T A Schmidt V M Haughton 《AJNR. American journal of neuroradiology》1997,18(7):1325
PURPOSETo study the relationship of lumbar facet joint tropism to degeneration of the cartilage and subcortical bone in the facet joints and the effect of tropism in intervertebral disk degeneration.METHODSThe orientation of 104 cadaveric lumbar facet joints with respect to sagittal plane was measured on CT scans, and the joints were classified as having no tropism, mild tropism, or severe tropism. On MR images, the severity of cartilage degeneration and bony sclerosis was measured. The correlation between tropism and degeneration was calculated, as was the relationship among age, spinal level, and degeneration.RESULTSWe identified four spinal levels with severe tropism, six with moderate tropism, and 94 without tropism. Cartilage degeneration was not significantly more severe in the joints with tropism than in the joints without. Sclerosis was slightly greater in the joints with tropism than in the joints without it. Sclerosis and cartilage degeneration were significantly related to age and spinal level.CONCLUSIONAge, spinal level, and overall facet joint angle are more important factors in facet joint degeneration than is tropism. 相似文献
100.
K. Sjölund S. Fasth R. Ekman L. Hultén H. Jiborn S. Nordgren & F. Sundler 《Neurogastroenterology and motility》1997,9(3):143-150
Tissue specimens from the large bowel of 18 patients with long-standing slow transit constipation were investigated to determine the distribution and density of several neuropeptides and amines in the enteric nerve system, and also of endocrine cells in comparison to normal individuals. CGRP (calcitonin gene-related peptide), galanin, glucagon, GRP (gastrin-releasing peptide), metenkephalin, motilin, neuropeptide Y (NPY), PACAP, peptide YY (PYY), serotonin, somatostatin, substance P and VIP were studied by immunohistochemistry. Tissue concentrations of VIP, substance P and galanin were also measured by radioimmunoassay. Significantly increased VIP, SP and galanin contents were found in specimens from the ascending colon. Levels of VIP and galanin were also increased in the transverse colon. Immunohistochemistry revealed only marginal changes with an increased density of PACAP nerve fibres in the smooth muscle and of VIP and PACAP nerves in the myenteric plexus of the transverse colon. In the descending colon substance P and NPY immunoreactivity were also increased in the myenteric plexus while the density of VIP nerve fibres was reduced in the mucosa/submucosa. The frequency of PYY-containing cells and the 5-HT-containing cells in the ascending colon was significantly increased in the constipated patients. 相似文献