全文获取类型
收费全文 | 144728篇 |
免费 | 10105篇 |
国内免费 | 578篇 |
专业分类
耳鼻咽喉 | 1504篇 |
儿科学 | 4393篇 |
妇产科学 | 2545篇 |
基础医学 | 19144篇 |
口腔科学 | 2656篇 |
临床医学 | 14624篇 |
内科学 | 30498篇 |
皮肤病学 | 1640篇 |
神经病学 | 14060篇 |
特种医学 | 4557篇 |
外国民族医学 | 1篇 |
外科学 | 20720篇 |
综合类 | 2043篇 |
现状与发展 | 1篇 |
一般理论 | 167篇 |
预防医学 | 13111篇 |
眼科学 | 3742篇 |
药学 | 10179篇 |
10篇 | |
中国医学 | 304篇 |
肿瘤学 | 9512篇 |
出版年
2023年 | 763篇 |
2022年 | 1216篇 |
2021年 | 2751篇 |
2020年 | 1673篇 |
2019年 | 2777篇 |
2018年 | 3176篇 |
2017年 | 2285篇 |
2016年 | 2675篇 |
2015年 | 3062篇 |
2014年 | 4480篇 |
2013年 | 6369篇 |
2012年 | 9600篇 |
2011年 | 10234篇 |
2010年 | 5599篇 |
2009年 | 5198篇 |
2008年 | 9088篇 |
2007年 | 9670篇 |
2006年 | 9156篇 |
2005年 | 9185篇 |
2004年 | 8696篇 |
2003年 | 8080篇 |
2002年 | 7835篇 |
2001年 | 1676篇 |
2000年 | 1393篇 |
1999年 | 1670篇 |
1998年 | 1708篇 |
1997年 | 1438篇 |
1996年 | 1176篇 |
1995年 | 1170篇 |
1994年 | 1015篇 |
1993年 | 998篇 |
1992年 | 1029篇 |
1991年 | 908篇 |
1990年 | 871篇 |
1989年 | 834篇 |
1988年 | 775篇 |
1987年 | 765篇 |
1986年 | 724篇 |
1985年 | 773篇 |
1984年 | 811篇 |
1983年 | 759篇 |
1982年 | 876篇 |
1981年 | 803篇 |
1980年 | 681篇 |
1979年 | 583篇 |
1978年 | 527篇 |
1977年 | 473篇 |
1976年 | 433篇 |
1975年 | 412篇 |
1974年 | 426篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
David S. Park Paul Manowitz Stanley Stein Ronald D. Poretz 《Alcoholism, clinical and experimental research》1996,20(2):234-239
Several electrophoretic forms of human platelet arylsulfatase A (ASA), including variant type IIIa and normal type IVa , have been identified by nondenaturing polyacrylamide gel electrophoresis. An alcoholic population that we have analyzed is enriched in variant type IIIa compared with nonalcoholic psychiatric and normal controls. Individuals with the IIIa enzyme possess greatly reduced levels of ASA activity. To understand further the structural basis for the differences and their potential biological consequences, the nature of the ASA variant expressed by fibroblasts from different individuals was explored. The electrophoretic patterns of fibroblast ASA from the IIIa and IVa individuals differ in degree of phosphorylation. Furthermore, fibroblast ASA from IIIa individuals lacks an N -linked glycan found in ASA from IVa individuals. In addition, differences in peptide and/or posttranslational modification unrelated to the N -linked carbohydrate or phosphorylation exist between the fibroblast ASA from IIIa and IVa individuals. The finding that both fibroblasts and platelets exhibit related electrophoretic isoform patterns characteristic of the donor's ASA type allows for the use of fibroblasts to study the impact of ethanol on the metabolism of cells possessing different ASA types. 相似文献
52.
D H Russell N E Zorn A R Buckley P D Crowe M D Sauro E M Hadden R V Farese H E Laird 《European journal of pharmacology》1990,188(2-3):139-152
Prolactin (PRL) and other trophic factors rapidly activate a nuclear pool(s) of protein kinase C (nPKC) in purified splenocyte nuclei. The PRL also enhanced [2-3H]glycerol incorporation into nuclear mono- and triacylglycerol. An assay was devised which not only probed the ability of the hormone to activate protein kinase C (PKC) but also demonstrated the presence of nuclear substrates. Using this methodology, a biphasic concentration-response curve to PRL was observed. Heterologous species of PRL and various growth factors also activated nPKC. The PRL-induced nPKC stimulation was antagonized by various immunomodulators, G protein-coupling inhibitors, PKC inhibitors, a calmodulin inhibitor, and a peripheral benzodiazepine agonist and antagonist. A monoclonal antibody to PKC, anti-rat PRL antiserum and a monoclonal anti-rat PRL receptor antibody antagonized PRL-induced PKC-dependent nuclear phosphorylation, further implicating nPKC and a PRL receptor-mediated activation process. Nuclear PKC may be a major target for trophic regulation in response to both positive and negative growth signals. 相似文献
53.
L B Russell J E Sisk 《International journal of technology assessment in health care》1988,4(2):269-286
This paper reviews the evolution of U.S. policy toward medical technology in areas such as cost containment, regulation of devices and drugs, and third party reimbursement. In addition the authors chronicle the diffusion of major medical technologies, procedures, and organizational innovations in the United States. Finally, the article provides tentative observations on the effect of recent policy changes and concludes with some recommendations for the future. 相似文献
54.
55.
56.
This study examined the relations betweensociotropy, autonomy, and stress severity ratings forhypothetical life events that were objectivelycategorized as interpersonal or achievement-related infocus. The hypothesis that sociotropy and autonomyserve as vulnerability factors to dysphoria in thepresence of life stress that matches the theme of thevulnerability was also examined in 6-week and 12-week follow-up evaluations. Results provided onlypartial support for the predicted relations amongsociotropy, autonomy, and perceived stress severityratings of interpersonal and achievement-related events. Longitudinal results failed to support thehypothesis that sociotropy and autonomy serve asvulnerability factors for matching interpersonal andachievement-related stress. It was concluded thatobjectively categorizing life events as interpersonal orachievement-related is problematic given that themeaning of life events can vary across individuals, andthat these meanings are likely to vary partly as a function of sociotropy and autonomy. 相似文献
57.
Kevin G Becker Insong J Lee James W Nagle Rachel D Canning Ameer M Gado Rosarelis Torres Mihael H Polymeropoulos Paul T Massa WilliamE Biddison Paul D Drew 《International journal of developmental neuroscience》1997,15(7):73
We describe a novel human zinc finger cNDA, C2H2-171. This cDNA represents an mRNA which encodes a protein of 484 amino acids and a calculated molecular weight of 54 kD. Four zinc finger-like domains are found in the C-terminal end of the protein. At the N-terminus, C2H2-171 contains a POZ/tramtrack-like domain similar to that found in the tumor associated zinc finger proteins LAZ-3/BCL-6 and PLZ-F, as well as in non-zinc finger proteins. C2H2-171 RNA is preferentially expressed in the brain, and increases during the course of murine development, with maximal expression in the adult. C2H2-171 RNA is differentially expressed in brain regions, with the highest level of expression in the cerebellum. C2H2-171 RNA was expressed at high levels in primary cerebellar granule cell neurons compared to astrocytes. The gene encoding C2H2-171 is highly conserved in vertebrates, and maps to the terminus of human chromosome 1 (1q44-ter). This chromosomal location is associated with a number of cytogenetic aberrations including those involving brain developmental anomalies and tumorigenesis. These data suggest that C2H2-171 may play an important role in vertebrate brain development and function. 相似文献
58.
Autosomal dominant neovascular inflammatory vitreoretinopathy 总被引:1,自引:0,他引:1
S R Bennett J C Folk A E Kimura S R Russell E M Stone E M Raphtis 《Ophthalmology》1990,97(9):1125-35; discussion 1135-6
Twenty-eight of 61 members of a six-generation family are affected by an autosomal dominant eye disease which has not been described previously. Affected patients are asymptomatic in early adulthood, but have vitreous cells and the selective loss of the b-wave on the electroretinogram. Later, peripheral retinal scarring and pigmentation, peripheral arteriolar closure, and neovascularization of the peripheral retina at the ora serrata or occasionally neovascularization of the optic disc develop. Cystoid macular edema, vitreous hemorrhage, tractional retinal detachment, and neovascular glaucoma can cause profound visual loss. Vitrectomy reduces traction on the retina and allows for retinal reattachment. The role of argon laser photocoagulation or cryopexy in reducing the neovascular complications remains uncertain. 相似文献
59.
Molecular biology of urological tumours 总被引:1,自引:0,他引:1
60.
Frances Rudnick Levin Judith M. Hess David A. Gorelick Nancy A. Kreiter Paul J. Fudala 《The American journal on addictions / American Academy of Psychiatrists in Alcoholism and Addictions》1993,2(2):109-115
The authors systematically evaluated the frequency patterns of cocaine use in 85 cocaine-dependent outpatients and found four patterns of use: continuous (27%), intermittent patterned (35%), intermittent nonpatterned (25%), and occasional (13%). Few subjects reported consistent cycling between binges and crashes. There were no significant differences in patterns of use associated with gender, race, educational level, route of administration, or recency of heroin use. Continuous users and occasional users were older than intermittent users. Because different contingencies may control patterned vs. nonpatterned cocaine use, pattern of use may have implications for treatment, even in individuals reporting similar amounts of cocaine use. 相似文献