全文获取类型
收费全文 | 3439篇 |
免费 | 251篇 |
国内免费 | 24篇 |
专业分类
耳鼻咽喉 | 11篇 |
儿科学 | 115篇 |
妇产科学 | 49篇 |
基础医学 | 441篇 |
口腔科学 | 55篇 |
临床医学 | 369篇 |
内科学 | 733篇 |
皮肤病学 | 34篇 |
神经病学 | 305篇 |
特种医学 | 136篇 |
外科学 | 446篇 |
综合类 | 130篇 |
预防医学 | 289篇 |
眼科学 | 22篇 |
药学 | 366篇 |
中国医学 | 6篇 |
肿瘤学 | 207篇 |
出版年
2022年 | 32篇 |
2021年 | 74篇 |
2020年 | 33篇 |
2019年 | 69篇 |
2018年 | 63篇 |
2017年 | 55篇 |
2016年 | 69篇 |
2015年 | 73篇 |
2014年 | 93篇 |
2013年 | 157篇 |
2012年 | 205篇 |
2011年 | 198篇 |
2010年 | 119篇 |
2009年 | 117篇 |
2008年 | 171篇 |
2007年 | 198篇 |
2006年 | 172篇 |
2005年 | 156篇 |
2004年 | 159篇 |
2003年 | 152篇 |
2002年 | 112篇 |
2001年 | 86篇 |
2000年 | 73篇 |
1999年 | 72篇 |
1998年 | 50篇 |
1997年 | 44篇 |
1996年 | 37篇 |
1995年 | 32篇 |
1994年 | 31篇 |
1993年 | 28篇 |
1992年 | 38篇 |
1991年 | 35篇 |
1990年 | 57篇 |
1989年 | 42篇 |
1988年 | 47篇 |
1987年 | 37篇 |
1986年 | 25篇 |
1985年 | 33篇 |
1984年 | 25篇 |
1983年 | 22篇 |
1982年 | 23篇 |
1981年 | 26篇 |
1980年 | 22篇 |
1979年 | 40篇 |
1978年 | 23篇 |
1977年 | 23篇 |
1974年 | 21篇 |
1973年 | 26篇 |
1972年 | 28篇 |
1971年 | 26篇 |
排序方式: 共有3714条查询结果,搜索用时 15 毫秒
1.
2.
There is growing interest in the phenomenon of long-term depression (LTD) of synaptic efficacy that, together with long-term potentiation (LTP), is a putative information storage mechanism in mammalian brain. In neural network models, multiple learning rules have been used for LTD induction. Similarly, in neurophysiological studies of hippocampal synaptic plasticity, a variety of activity patterns have been effective at inducing LTD, although experimental paradigms are still being optimized. In this review the authors summarize the major experimental paradigms and compare what is known about the mechanisms of LTD induction. Although all paradigms appear to initiate a cascade of events leading to an elevated level of Ca2+ postsynaptically, the extent to which these paradigms involve common expression mechanisms has not yet been tested. The authors discuss several critical experiments that would address this latter issue. Numerous questions about the properties and mechanisms of LTD(s) in the hippocampus remain to be answered, but it is clear that LTD has finally arrived, and will soon be attracting attention equal to its flip side, LTP. © 1994 Wiley-Liss, Inc. 相似文献
3.
Christie AB 《Postgraduate medical journal》1949,25(287):409-412
4.
Summary Patients with insulin-dependent diabetes mellitus (IDDM) possess antibodies to the cytoplasmic domains of two closely related
tyrosine phosphatase-like proteins, IA-2 and phogrin, previously detected as 40 kDa and 37 kDa tryptic fragments, respectively.
A higher proportion of IDDM patients possess antibodies to IA-2 than to phogrin, and autoimmunity to phogrin might arise through
cross-reactivity with the highly homologous IA-2. In this study, we have investigated the major regions of IA-2 recognized
by antibodies in IDDM patients and examined the ability of phogrin to block antibody binding to these regions as a measure
of cross-reactivity. Analysis of antibody binding to in vitro transcribed and translated polypeptides representing different
regions of the cytoplasmic domain of IA-2 identified five different patterns of reactivity with antibodies in IDDM. Protein
footprinting analysis, whereby polypeptide fragments generated on protease treatment of immune complexes are studied, indicated
considerable heterogeneity in antibody recognition of IA-2, even between sera with similar reactivity to deletion mutants.
Blocking studies with recombinant phogrin indicated that IA-2 antibodies recognize epitopes that are both unique to IA-2 and
shared with phogrin. The amino-terminal 150 amino acids of the cytoplasmic domain of IA-2 encompass epitopes that are not
represented on phogrin, whereas shared epitopes are localized within the carboxy-terminal 220 amino acids. The results demonstrate
considerable heterogeneity between IDDM patients in autoantibody recognition of IA-2 in IDDM, whereas antibody recognition
of phogrin is restricted in most patients to epitopes also present on IA-2. [Diabetologia (1997) 40: 1327–1333]
Received: 4 April 1997 and in revised form: 2 July 1997 相似文献
5.
Werner Christie 《中国医疗前沿》2007,(1):11
挪威是一个实行市场经济的国家,我们选择了这样的体系是因为它能够有效地解决很多——但不是全部——生产、货物流通以及服务的竞争问题。在发展一个国际化的市场体系的同时,挪威也发展了强大的公共机构和公共服务。一个有效的市场并不意味着我们就不需要公共部门,或者像有些流行观念所认为的,任何公共服务都应该私有化。其实,一个市场是需要严格的监管,需要与公共组织相配合才能良好地运转,而且需要一个广泛覆盖并且有效的公共部门,来补充提供那些市场无法有效而让人满意地提供的服务,比如教育、医疗和环境保护等。但是,这些公共服务不能由… 相似文献
6.
7.
MHC class II (I-A) region control of the IgE antibody repertoire to the ABA-1 allergen of the nematode Ascaris 总被引:4,自引:0,他引:4
下载免费PDF全文
![点击此处可从《Immunology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
ABA-1 is an approximately 14,000 molecular weight (MW) allergen which is among the most abundant proteins synthesized by the nematode parasite Ascaris. IgG and IgE responses to it are major histocompatibility complex (MHC)-restricted in rodents and have only been found to occur in rats of the RT1u haplotype and mice of the H-2s haplotype. Humans infected with the parasite vary substantially in their immune response to the allergen, but the genetic basis for this unknown. H-2 recombinant mice were used to identify the region within the MHC controlling antibody responses to the allergen. IgG antibody to immunoaffinity purified ABA-1 was assayed by radio-immunoassay and IgE by passive cutaneous anaphylaxis. This showed that the restriction element is the I-A molecule and that there was some evidence for I-E modulation of the level of response. 相似文献
8.
Angela
J. Dean James Bell Macdonald
J. Christie Richard
P. Mattick 《European psychiatry》2004,19(8):510-513
Research suggests that buprenorphine may possess antidepressant activity. The Beck Depression Inventory was completed at baseline and 3 months by heroin dependent subjects receiving either buprenorphine or methadone maintenance as part of a larger, pre-existing, double blind trial conducted by NDARC (Australia). Depressive symptoms improved in all subjects, with no difference between methadone and buprenorphine groups, suggesting no differential benefit on depressive symptoms for buprenorphine compared to methadone. 相似文献
9.
10.