全文获取类型
收费全文 | 1732篇 |
免费 | 160篇 |
国内免费 | 3篇 |
专业分类
1895篇 |
出版年
2023年 | 5篇 |
2022年 | 11篇 |
2021年 | 34篇 |
2020年 | 11篇 |
2019年 | 15篇 |
2018年 | 33篇 |
2017年 | 24篇 |
2016年 | 42篇 |
2015年 | 72篇 |
2014年 | 72篇 |
2013年 | 130篇 |
2012年 | 125篇 |
2011年 | 105篇 |
2010年 | 78篇 |
2009年 | 82篇 |
2008年 | 104篇 |
2007年 | 122篇 |
2006年 | 100篇 |
2005年 | 112篇 |
2004年 | 97篇 |
2003年 | 87篇 |
2002年 | 90篇 |
2001年 | 14篇 |
2000年 | 9篇 |
1999年 | 18篇 |
1998年 | 19篇 |
1997年 | 21篇 |
1996年 | 6篇 |
1995年 | 14篇 |
1994年 | 19篇 |
1993年 | 13篇 |
1992年 | 10篇 |
1991年 | 11篇 |
1990年 | 21篇 |
1989年 | 22篇 |
1988年 | 12篇 |
1987年 | 11篇 |
1986年 | 6篇 |
1985年 | 11篇 |
1984年 | 10篇 |
1983年 | 11篇 |
1982年 | 6篇 |
1981年 | 7篇 |
1980年 | 7篇 |
1979年 | 5篇 |
1978年 | 5篇 |
1977年 | 6篇 |
1976年 | 6篇 |
1974年 | 8篇 |
1968年 | 4篇 |
排序方式: 共有1895条查询结果,搜索用时 15 毫秒
91.
Cutting edge: susceptibility to psoriatic arthritis: influence of activating killer Ig-like receptor genes in the absence of specific HLA-C alleles 总被引:21,自引:0,他引:21
Martin MP Nelson G Lee JH Pellett F Gao X Wade J Wilson MJ Trowsdale J Gladman D Carrington M 《Journal of immunology (Baltimore, Md. : 1950)》2002,169(6):2818-2822
NK cell activity is partially controlled through interactions between killer Ig-like receptors (KIR) on NK cells and their respective HLA class I ligands. Independent segregation of HLA and KIR genes, along with KIR specificity for particular HLA allotypes, raises the possibility that any given individual may express KIR molecules for which no ligand is present. Inhibitory receptor genes KIR2DL2/3 and KIR2DL1 were present in nearly all subjects sampled in this study, whereas their respective activating homologs, KIR2DS2 and KIR2DS1, are each present in about half of the subjects. In this work we report that subjects with activating KIR2DS1 and/or KIR2DS2 genes are susceptible to developing psoriatic arthritis, but only when HLA ligands for their homologous inhibitory receptors, KIR2DL1 and KIR2DL2/3, are missing. Absence of ligands for inhibitory KIRs could potentially lower the threshold for NK (and/or T) cell activation mediated through activating receptors, thereby contributing to pathogenesis of psoriatic arthritis. 相似文献
92.
A spontaneous CD8 T cell-dependent autoimmune disease to an antigen expressed under the human keratin 14 promoter 总被引:3,自引:0,他引:3
McGargill MA Mayerova D Stefanski HE Koehn B Parke EA Jameson SC Panoskaltsis-Mortari A Hogquist KA 《Journal of immunology (Baltimore, Md. : 1950)》2002,169(4):2141-2147
Using a previously described human keratin 14 (K14) promoter, we created mice expressing a peptide Ag (OVAp) in epithelial cells of the skin, tongue, esophagus, and thymus. Double transgenic mice that also express a TCR specific for this Ag (OT-I) showed evidence for Ag-driven receptor editing in the thymus. Surprisingly, such mice exhibited a severe autoimmune disease. In this work we describe the features of this disease and demonstrate that it is dependent on CD8 T cells. Consistent with the Ag expression pattern dictated by the human K14 promoter, an inflammatory infiltrate was observed in skin and esophagus and around bile ducts of the liver. We also observed a high level of TNF-alpha in the serum. Given that Ag expression in the thymus induced development of T cells with dual TCR reactivity, and that dual-reactive cells have been suggested to have autoimmune potential, we tested whether they were a causal factor in the disease observed here. We found that OT-I/K14-OVAp animals on a recombinase-activating gene-deficient background still suffered from disease. In addition, OT-I animals expressing OVA broadly in all tissues under a different promoter did not experience disease, despite having a similar number of dual-specific T cells. Thus, in this model it would appear that dual-reactive T cells do not underlie autoimmune pathology. Finally, we extended these observations to a second transgenic system involving 2C TCR-transgenic animals expressing the SIY peptide Ag with the hK14 promoter. We discuss the potential relationship between autoimmunity and self-Ags that are expressed in stratified epithelium. 相似文献
93.
94.
The role of Ras in T lymphocyte activation 总被引:4,自引:0,他引:4
95.
96.
The influence of surface wettability on the adhesion strength of settled spores of the green alga enteromorpha and the diatom amphora 总被引:1,自引:0,他引:1
Finlay JA Callow ME Ista LK Lopez GP Callow JA 《Integrative and comparative biology》2002,42(6):1116-1122
In this paper we report on the effect of surface wettabilityon surface selection and adhesion properties of settled (adhered)spores of the biofouling marine alga Enteromorpha and cellsof the diatom Amphora, through the use of patterned self-assembledmonolayers (SAMs). The SAMs were formed from alkanethiols terminatedwith methyl (CH3) or hydroxyl (OH) groups, or mixtures of thetwo, creating a discontinuous gradient of wettability as measuredby advancing water contact angle. In the case of Enteromorpha,primary adhesion, as measured by the transition from a motilespore to a settled, sessile organism, is strongly promoted bythe hydrophobic surfaces. On the other hand, adhesion strengthof the settled spores, as measured by resistance to detachmentin a turbulent flow cell, is greatest on a hydrophilic surface.In the case of Amphora, there is little influence of surfacewettability on the primary adhesion of this organism, but motilityis inhibited at contact angles 相似文献
97.
98.
Griffis ER Altan N Lippincott-Schwartz J Powers MA 《Molecular biology of the cell》2002,13(4):1282-1297
99.
100.
Lactosylceramide (LacCer) is a pivotal intermediate in the metabolism of higher gangliosides, localizes to sphingolipid-sterol "rafts," and has been implicated in cellular signaling. To provide a fundamental characterization of LacCer phase behavior and intermolecular packing, LacCer containing different saturated (16:0, 18:0, 24:0) or monounsaturated (18:1(Delta9), 24:1(Delta15)) acyl chains were synthesized and studied by differential scanning calorimetry and Langmuir film balance approaches. Compared to related sphingoid- and glycerol-based lipids, LacCers containing saturated acyl chains display relatively high thermotropic and pressure-induced transitions. LacCer monolayer films are less elastic in an in-plane sense than sphingomyelin films, but are somewhat more elastic than galactosylceramide films. Together, these findings indicate that the disaccharide headgroup only marginally disrupts gel phase packing and orients more perpendicular than parallel to the interface. This contrasts the reported behavior of digalactosyldiglycerides with saturated acyl chains. Introducing single cis double bonds into the LacCer acyl chains dramatically lowers the high thermotropic and pressure-induced transitions. Greater reductions occur when cis double bonds are located near the middle of the acyl chains. The results are discussed in terms of how an extended disaccharide headgroup can enhance interactions among naturally abundant LacCers with saturated acyl chains. 相似文献