首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   545篇
  免费   36篇
  国内免费   3篇
儿科学   21篇
妇产科学   3篇
基础医学   77篇
口腔科学   11篇
临床医学   23篇
内科学   93篇
皮肤病学   9篇
神经病学   60篇
特种医学   36篇
外科学   18篇
综合类   8篇
预防医学   14篇
眼科学   17篇
药学   175篇
肿瘤学   19篇
  2021年   6篇
  2017年   7篇
  2016年   8篇
  2015年   7篇
  2014年   13篇
  2013年   19篇
  2012年   17篇
  2011年   15篇
  2010年   12篇
  2009年   25篇
  2008年   11篇
  2007年   14篇
  2006年   13篇
  2005年   8篇
  2004年   12篇
  2003年   11篇
  2002年   7篇
  2001年   7篇
  2000年   10篇
  1999年   15篇
  1998年   12篇
  1997年   13篇
  1996年   14篇
  1995年   13篇
  1994年   11篇
  1993年   6篇
  1992年   17篇
  1991年   9篇
  1990年   9篇
  1989年   16篇
  1988年   15篇
  1987年   16篇
  1986年   22篇
  1985年   19篇
  1984年   12篇
  1983年   10篇
  1982年   8篇
  1981年   7篇
  1980年   7篇
  1979年   8篇
  1978年   10篇
  1977年   5篇
  1976年   10篇
  1975年   8篇
  1974年   7篇
  1973年   8篇
  1972年   11篇
  1971年   11篇
  1970年   7篇
  1969年   5篇
排序方式: 共有584条查询结果,搜索用时 15 毫秒
1.
The origin and functional significance of vasopressin (AVP)‐containing fibres in limbic regions has been an ongoing subject of investigation for several years. We have previously identified AVP‐magnocellular neurones of rat hypothalamus that provide glutamatergic projections to the hippocampus, amygdala, lateral habenula and locus coeruleus. However, we also reported AVP‐immunopositive fibres in those regions that are thin and make Gray type II synapses, which are unlikely to be of magnocellular origin. Therefore, in the present study, we characterised AVP mRNA co‐expression with expression of mRNAs marking glutamatergic (vesicular glutamate transporter [VGLUT]) and GABAergic (vesicular GABA transporter [VGAT]) neuronal traits in rat and mouse brain, using high‐resolution in situ hybridisation methods, including a radio‐ribonucleotide and RNAscope 2.5 HD duplex assay, with Slc17a7, Slc17a6, Slc32a1 and Avp probes corresponding to mRNAs of VGLUT1, VGLUT2, VGAT and AVP, respectively. We located 18 cell groups expressing Avp and identified their molecular signatures for VGLUT and VGAT mRNA expression. Avp cell groups of hypothalamus and midbrain are mainly VGLUT mRNA‐expressing, whereas those in regions derived from cerebral nuclei are mainly VGAT mRNA‐expressing, suggesting a functional segregation of glutamate/GABA co‐transmission with AVP. A newly identified Slc17a7 and Slc17a6 (but not Slc32a1) expressing vasopressinergic cell group was found in layer II‐III neurones of the central entorhinal cortex, which projects to the hippocampus. These data support the notion of a complex role for AVP with respect to modulating multiple central circuits controlling behaviour in specific ways depending on co‐transmission with glutamate or GABA, potentially giving rise to a functional classification of AVPergic neurones in the central nervous system.  相似文献   
2.
F1FoATP synthase (ATP synthase) is a ubiquitous enzyme complex in eukaryotes. In general it is localized to the mitochondrial inner membrane and serves as the last step in the mitochondrial oxidative phosphorylation of ADP to ATP, utilizing a proton gradient across the inner mitochondrial membrane built by the complexes of the electron transfer chain. However some cell types, including tumors, carry ATP synthase on the cell surface. It was suggested that cell surface ATP synthase helps tumor cells thriving on glycolysis to survive their high acid generation. Angiostatin, aurovertin, resveratrol, and antibodies against the α and β subunits of ATP synthase were shown to bind and selectively inhibit cell surface ATP synthase, promoting tumor cell death. Here we show that ATP synthase β (ATP5B) is present on the cell surface of mouse pheochromocytoma cells as well as tumor cells of human SDHB-derived paragangliomas (PGLs), while being virtually absent on chromaffin primary cells from bovine adrenal medulla by confocal microscopy. The cell surface location of ATP5B was verified in the tissue of an SDHB-derived PGL by immunoelectron microscopy. Treatment of mouse pheochromocytoma cells with resveratrol as well as ATP5B antibody led to statistically significant proliferation inhibition. Our data suggest that PGLs carry ATP synthase on their surface that promotes cell survival or proliferation. Thus, cell surface ATP synthase may present a novel therapeutic target in treating metastatic or inoperable PGLs.  相似文献   
3.
Pituitary Adenylate Cyclase-Activating Polypeptide (PACAP) plays an important role in cytoprotection, inflammation and cardiovascular regulation. Thus, we studied the involvement of PACAP in atherogenesis. Differentiated human THP-1 macrophages (MΦ) were stimulated with oxidized low-density lipoproteins (oxLDL) and the influence of PACAP38 treatment on lipid content and TNF release was determined. To test the effect of PACAP deficiency (PACAP?/?) on the development of atherosclerosis under standard chow (SC) or cholesterol-enriched diet (CED) in vivo, PACAP?/? mice were crossbred with ApoE?/? to generate PACAP?/?/ApoE?/? mice. Blood cholesterol and triglyceride levels were quantified. Lumen stenosis in the brachiocephalic trunk, cellularity and amounts of pro-inflammatory as well as autophagy-, apoptosis- and necroptosis-relevant proteins were analysed in atherosclerotic plaques by quantitative immunohistochemistry. In vitro, PACAP38 inhibited oxLDL-induced intracellular lipid storage as well as TNF release in MФ. In vivo, after SC, but not under CED, PACAP?/?/ApoE?/? mice showed an increased lumen stenosis compared to ApoE?/? mice. In atherosclerotic plaques of PACAP?/?/ApoE?/? mice, the immunoreactive areas of TNF+, IL-1β+, autophagic, apoptotic and necroptotic cells were increased. In contrast, the overall cell density was decreased compared to ApoE?/? under SC, while no differences were seen under CED. Similar plasma cholesterol levels were observed in PACAP?/?/ApoE?/? and ApoE?/? mice under the respective feeding regime. Thus, PACAP?/-/ApoE?/? mice represent a novel mouse model of accelerated atherosclerosis where CED is not required. Our data indicate that PACAP acts as an endogenous atheroprotective neuropeptide. Thus, stable PACAP agonists may have potential as anti-atherosclerotic therapeutics. The specific PACAP receptor(s) mediating atheroprotection remain(s) to be identified.  相似文献   
4.
5.
The adenosine triphosphate‐binding cassette transport protein P‐glycoprotein (ABCB1) is involved in the export of beta‐amyloid from the brain into the blood, and there is evidence that age‐associated deficits in cerebral P‐glycoprotein content may be involved in Alzheimer''s disease pathogenesis. P‐glycoprotein function and expression can be pharmacologically induced by a variety of compounds including extracts of Hypericum perforatum (St. John''s Wort). To clarify the effect of St. John''s Wort on the accumulation of beta‐amyloid and P‐glycoprotein expression in the brain, St. John''s Wort extract (final hyperforin concentration 5%) was fed to 30‐day‐old male C57BL/6JAPP/PS1 +/− mice over a period of 60 or 120 days, respectively. Age‐matched male C57BL/6JAPP/PS1 +/− mice receiving a St. John''s Wort‐free diet served as controls. Mice receiving St. John''s Wort extract showed (i) significant reductions of parenchymal beta‐amyloid 1–40 and 1–42 accumulation; and (ii) moderate, but statistically significant increases in cerebrovascular P‐glycoprotein expression. Thus, the induction of cerebrovascular P‐glycoprotein may be a novel therapeutic strategy to protect the brain from beta‐amyloid accumulation, and thereby impede the progression of Alzheimer''s disease.  相似文献   
6.
Rift Valley fever virus (RVFV) is a vector-borne virus that causes high neonatal mortality in livestock and deadly haemorrhagic fever in humans. In this paper, we describe the generation of monoclonal antibodies (mabs) against all three structural proteins of RVFV (glycoproteins Gn and Gc and nucleocapsid protein NP). After immunization of BALB/c mice with individual recombinant proteins, a total of 45 clones secreting ELISA-reactive monoclonal antibodies against NP, Gn and Gc epitopes were obtained. Twelve clones were directed to NP, 28 to Gn, and 5 to Gc. Western blot analysis revealed that most of the mabs were reactive to linearized epitopes on recombinant as well as native virus proteins. Six mabs against NP, 21 against Gn and all mabs against Gc also detected conformational epitopes, as shown by indirect immunofluorescence on RVFV-infected cells. All of the mabs were evaluated for their use in a competition enzyme-linked immunosorbent assay (ELISA) for the detection of a RVFV infection. Several mabs were identified that competed with polyclonal rabbit serum, and one of them – mab Gn123, raised against Gn protein – was selected for a proof-of-principle study with field sera from a recent Rift Valley fever outbreak. The novel Gn-based competition ELISA demonstrated high performance, offering a promising alternative and addition to serological assays based on nucleocapsid protein.  相似文献   
7.
8.
9.
10.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号