全文获取类型
收费全文 | 20011篇 |
免费 | 1376篇 |
国内免费 | 23篇 |
专业分类
耳鼻咽喉 | 181篇 |
儿科学 | 725篇 |
妇产科学 | 736篇 |
基础医学 | 2489篇 |
口腔科学 | 311篇 |
临床医学 | 3070篇 |
内科学 | 3347篇 |
皮肤病学 | 397篇 |
神经病学 | 1875篇 |
特种医学 | 334篇 |
外科学 | 1997篇 |
综合类 | 349篇 |
一般理论 | 20篇 |
预防医学 | 2478篇 |
眼科学 | 388篇 |
药学 | 1238篇 |
中国医学 | 20篇 |
肿瘤学 | 1455篇 |
出版年
2023年 | 117篇 |
2022年 | 177篇 |
2021年 | 453篇 |
2020年 | 341篇 |
2019年 | 443篇 |
2018年 | 481篇 |
2017年 | 344篇 |
2016年 | 412篇 |
2015年 | 473篇 |
2014年 | 638篇 |
2013年 | 919篇 |
2012年 | 1435篇 |
2011年 | 1589篇 |
2010年 | 828篇 |
2009年 | 687篇 |
2008年 | 1310篇 |
2007年 | 1366篇 |
2006年 | 1269篇 |
2005年 | 1270篇 |
2004年 | 1210篇 |
2003年 | 1181篇 |
2002年 | 961篇 |
2001年 | 217篇 |
2000年 | 217篇 |
1999年 | 171篇 |
1998年 | 196篇 |
1997年 | 195篇 |
1996年 | 169篇 |
1995年 | 118篇 |
1994年 | 114篇 |
1993年 | 111篇 |
1992年 | 164篇 |
1991年 | 163篇 |
1990年 | 157篇 |
1989年 | 136篇 |
1988年 | 118篇 |
1987年 | 110篇 |
1986年 | 131篇 |
1985年 | 112篇 |
1984年 | 115篇 |
1983年 | 98篇 |
1982年 | 79篇 |
1981年 | 59篇 |
1980年 | 72篇 |
1979年 | 81篇 |
1978年 | 52篇 |
1977年 | 44篇 |
1976年 | 33篇 |
1974年 | 37篇 |
1971年 | 33篇 |
排序方式: 共有10000条查询结果,搜索用时 171 毫秒
111.
Impact of a Summer Camp Experience on Daily Activity and Family Interactions Among Children with Cancer 总被引:1,自引:0,他引:1
Smith Karen E.; Gotlieb Sharon; Gurwitch Robin H.; Blotcky Alan D. 《Journal of pediatric psychology》1987,12(4):533-542
Eighteen pediatric cancer patients and their families participatedin a longitudinal study to assess the effects of a camp experienceon daily activity and family interactions. Based on maternalreport, changes were found in the amount of time these childrenspent in social, physical, and self-engaged activities. Mothersand a sibling closest in age to the patient also noted changesin their own frequency of activities spent with the family andwith others. These changes were evident when comparing measuresobtained 2 weeks prior to and 2 weeks after camp. Many changeswere still present 1 month after attending camp. These datasupport the use of a camp experience as an intervention to facilitatea return to more normal, healthy functioning by pediatric cancerpatients and their families. 相似文献
112.
Characterization of an immunoprotective protein complex of Anaplasma marginale by cloning and expression of the gene coding for polypeptide Am105L. 总被引:4,自引:13,他引:4
下载免费PDF全文
![点击此处可从《Infection and immunity》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Immunization with an Anaplasma marginale surface protein complex containing two polypeptides (Am105U and Am105L), each having a molecular weight of 105,000, protected cattle against challenge with virulent organisms. These polypeptides were immunoprecipitated together from detergent extracts of A. marginale by a neutralizing monoclonal antibody. After surface radioiodination of intact parasites, both Am105U and Am105L contained the radiolabel. To define the structural and antigenic relationships between Am105U and Am105L and to determine individual efficacies as protective immunogens, we cloned and expressed A. marginale DNA in Escherichia coli. We identified recombinant bacteria which expressed a novel protein of 105,000 molecular weight as a major cellular component. The recombinant protein was structurally and antigenically homologous to Am105L. There were multiple, partially homologous copies of the cloned DNA sequence in the rickettsial genome. 相似文献
113.
Allicin inhibits SDF-1alpha-induced T cell interactions with fibronectin and endothelial cells by down-regulating cytoskeleton rearrangement, Pyk-2 phosphorylation and VLA-4 expression 总被引:2,自引:0,他引:2
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)
Sela U Ganor S Hecht I Brill A Miron T Rabinkov A Wilchek M Mirelman D Lider O Hershkoviz R 《Immunology》2004,111(4):391-399
Allicin, a major ingredient of fresh garlic extract that is produced during the crushing of garlic cloves, exerts various beneficial biological effects, including a broad spectrum of antimicrobial activity, antihyperlipidaemic and antihypertensive effects. However, how allicin affects the immune system is less well known, and its effect on human T cells has never been studied. Here, we examined the in-vitro effects of allicin on the functioning of T cells related to their entry to inflamed extravascular sites. We found that allicin (20-100 microm) inhibits the SDF-1alpha (CXCL12)-induced T cell migration through fibronectin (FN), and that this inhibition is mediated by the down-regulation of (i) the reorganization of cortical actin and the subsequent T cell polarization, and (ii) T cell adhesion to FN. Moreover, allicin also inhibited T cell adhesion to endothelial cells and transendothelial migration. The mechanisms underlying these inhibitory effects of allicin are associated with its ability to down-regulate the phosphorylation of Pyk2, an intracellular member of the focal adhesion kinases, and to reduce the expression of the VCAM-1- and FN-specific alpha4beta1-integrin (VLA-4). The ability of allicin to down-regulate these chemokine-induced and VLA-4-mediated T cell functions explains its beneficial biological effects in processes where T cells play an important role and suggests that allicin may be used therapeutically with chronic inflammatory diseases. 相似文献
114.
The rate of HIV-1 disease progression is influenced by several factors that include pathogen and host genetic variations and the quality of antiviral immune responses. The CD8+ cell non-cytotoxic antiviral response (CNAR) substantially suppresses HIV replication in CD4+ cells and is positively associated with an asymptomatic clinical state. Traditionally, the measurement of CNAR has required several culture procedures and costly reagents. Here we report the development and validation of a screening assay for detection of CNAR that accurately identifies individuals benefiting from this response. Use of the CNAR screening assay should facilitate the evaluation of this important immune parameter in studies of HIV pathogenesis, resistance to infection, and vaccine development. 相似文献
115.
Diagnosis of gastrointestinal stromal tumors: A consensus approach 总被引:258,自引:0,他引:258
Fletcher CD Berman JJ Corless C Gorstein F Lasota J Longley BJ Miettinen M O'Leary TJ Remotti H Rubin BP Shmookler B Sobin LH Weiss SW 《Human pathology》2002,33(5):459-465
As a result of major recent advances in understanding the biology of gastrointestinal stromal tumors (GISTs), specifically recognition of the central role of activating KIT mutations and associated KIT protein expression in these lesions, and the development of novel and effective therapy for GISTs using the receptor tyrosine kinase inhibitor STI-571, these tumors have become the focus of considerable attention by pathologists, clinicians, and patients. Stromal/mesenchymal tumors of the gastrointestinal tract have long been a source of confusion and controversy with regard to classification, line(s) of differentiation, and prognostication. Characterization of the KIT pathway and its phenotypic implications has helped to resolve some but not all of these issues. Given the now critical role of accurate and reproducible pathologic diagnosis in ensuring appropriate treatment for patients with GIST, the National Institutes of Health convened a GIST workshop in April 2001 with the goal of developing a consensus approach to diagnosis and morphologic prognostication. Key elements of the consensus, as described herein, are the defining role of KIT immunopositivity in diagnosis and a proposed scheme for estimating metastatic risk in these lesions, based on tumor size and mitotic count, recognizing that it is probably unwise to use the definitive term "benign" for any GIST, at least at the present time. 相似文献
116.
Equine infectious anemia virus (EIAV) is a lentivirus that causes persistent infections in horses. We hypothesized that high-avidity CTL specific for nonvariable epitopes might be associated with low viral load and minimal disease in EIAV-infected horses. To test this hypothesis, memory CTL (CTLm) responses were analyzed in two infected horses with high plasma viral loads and recurrent disease (progressors), and in two infected horses with low-to-undetectable viral loads and mild disease (nonprogressors). High-avidity CTLm in one progressor recognized an envelope gp90 epitope, and the data documented for the first time in EIAV that viral variation led to CTL escape. Each of the nonprogressors had high-to-moderate avidity CTLm directed against epitopes within Rev, including the nuclear export and nuclear localization domains. These results suggested that the epitope specificity of high- and moderate-avidity CTLm was an important determinant for disease outcome in the EIAV-infected horses examined. 相似文献
117.
118.
A gene for autosomal recessive limb-girdle muscular dystrophy maps to chromosome 2p 总被引:10,自引:3,他引:10
Bashlr Rumaisa; Strachan Tom; Keers Sharon; Stephenson Anthea; Mahjneh Ibrahim; Marconi Giamplero; Nashef Lina; Bushby Kate M. D. 《Human molecular genetics》1994,3(3):455-457
The limb-girdle muscular dystrophies are a clinically and geneticallyheterogeneous group of disorders. We have ostudied two largeinbred families of different ethnic origin and excluded linkageto LGMD2 on chromosome 15q and SCARMD on chromosome 13. Proceedingto a genomic linkage search, we have now identified linkageto markers D2S134 and D2S136 on chromosome 2p (maximum lod score3.57 at zero recombination). The phenotype in the two familieswas similar, with onset in the pelvic girdle musculature inthe late teens and usually relatively slow progression. Thiswork Identifies a second locus for autosomal recessive limb-girdlemuscular dystrophy. 相似文献
119.
Leao RN Oleskevich S Sun H Bautista M Fyffe RE Walmsley B 《Journal of neurophysiology》2004,91(2):1006-1012
We have investigated the fundamental properties of central auditory glycinergic synapses in early postnatal development in normal and congenitally deaf (dn/dn) mice. Glycinergic miniature inhibitory postsynaptic currents (mIPSCs) were recorded using patch-clamp methods in neurons from a brain slice preparation of the medial nucleus of the trapezoid body (MNTB), at 12-14 days postnatal age. Our results show a number of significant differences between normal and deaf mice. The frequency of mIPSCs is greater (50%) in deaf versus normal mice. Mean mIPSC amplitude is smaller in deaf mice than in normal mice (mean mIPSC amplitude: deaf, 64 pA; normal, 106 pA). Peak-scaled fluctuation analysis of mIPSCs showed that mean single channel conductance is greater in the deaf mice (deaf, 64 pS; normal, 45 pS). The mean decay time course of mIPSCs is slower in MNTB neurons from deaf mice (mean half-width: deaf, 2.9 ms; normal, 2.3 ms). Light- and electron-microscopic immunolabeling results showed that MNTB neurons from deaf mice have more (30%) inhibitory synaptic sites (postsynaptic gephyrin clusters) than MNTB neurons in normal mice. Our results demonstrate substantial differences in glycinergic transmission in normal and congenitally deaf mice, supporting a role for activity during development in regulating both synaptic structure (connectivity) and the fundamental (quantal) properties of mIPSCs at central glycinergic synapses. 相似文献
120.