全文获取类型
收费全文 | 1199篇 |
免费 | 89篇 |
国内免费 | 2篇 |
出版年
2024年 | 2篇 |
2023年 | 5篇 |
2022年 | 22篇 |
2021年 | 46篇 |
2020年 | 19篇 |
2019年 | 30篇 |
2018年 | 27篇 |
2017年 | 37篇 |
2016年 | 55篇 |
2015年 | 87篇 |
2014年 | 73篇 |
2013年 | 103篇 |
2012年 | 95篇 |
2011年 | 104篇 |
2010年 | 69篇 |
2009年 | 45篇 |
2008年 | 67篇 |
2007年 | 59篇 |
2006年 | 49篇 |
2005年 | 49篇 |
2004年 | 57篇 |
2003年 | 49篇 |
2002年 | 43篇 |
2001年 | 3篇 |
2000年 | 5篇 |
1999年 | 6篇 |
1998年 | 6篇 |
1997年 | 6篇 |
1996年 | 3篇 |
1995年 | 2篇 |
1992年 | 4篇 |
1991年 | 3篇 |
1990年 | 5篇 |
1989年 | 4篇 |
1988年 | 4篇 |
1987年 | 2篇 |
1986年 | 4篇 |
1985年 | 10篇 |
1983年 | 5篇 |
1982年 | 5篇 |
1981年 | 3篇 |
1979年 | 2篇 |
1978年 | 2篇 |
1976年 | 3篇 |
1975年 | 3篇 |
1969年 | 1篇 |
1968年 | 1篇 |
1964年 | 1篇 |
1963年 | 1篇 |
1961年 | 1篇 |
排序方式: 共有1290条查询结果,搜索用时 375 毫秒
91.
Costa BB Corrêa R De Souza MM Pretto JB Ardenghi JV De Campos-Buzzi F Cechinel Filho V 《Zeitschrift für Naturforschung. C, Journal of biosciences》2007,62(3-4):201-206
This paper describes the antinociceptive effects of tetrahydrophthalimides and related compounds in mice. Twenty compounds were obtained by the reaction of cis-1,2,3,6-tetrahydrophthalic anhydride with appropriate amines, dehydration, and addition to the imidic double bond. They were analyzed in the writhing test at 10 mg/kg given intraperitoneally. The most active compound 2-benzyl-5-morpholin-4-yl-hexahydroisoindole-1,3-dione (19) was studied on formalin, capsaicin, glutamate and hot plate models. The antinociceptive activity demonstrated by some studied compounds is promising, and some of them were more active than acetylsalicylic acid and paracetamol used as reference drugs in writhing tests in mice. Compound 19 was about 5-fold more potent than the reference drugs, being also effective by oral route and against the inflammatory response in the formalin test. The results suggest that compound 19 could be used as a model to obtain new and more potent antinociceptive agents. It exhibits an interesting antinociceptive profile, and does not interact with opioid systems. 相似文献
92.
The actute phase reaction mediated by the proinflammatory cytokine IL6 initiates a number of metabolic changes in the liver,
which may contribute to the pathogenesis of the septic shock during prolonged exposition. Here, the impact of IL6 on the hepatic
glucose providing capacity was studied by monitoring glycogen degradation and the expression of the gluconeogenic phosphoenolpyruvate
carboxykinase (PCK1) in rat livers during the daily feeding rhythm. Eight hours after i.p. injection of IL6, mRNA levels of
α2-macroglobulin, a prominent acute phase reactant in rat liver, were elevated as shown by Northern blot analysis and in situ
hybridization (ISH). PCK1 mRNA levels were decreased by IL6 to 50% of levels in untreated animals due to the reduction of
PCK1 mRNA in the periportal zone of the liver as shown by ISH. PCK1 enzyme activity was not affected by IL6. Glycogen degradation
was accelerated by IL6, which led to nearly complete depletion of glycogen pools in periportal areas 8 h after IL6 injection.
This was very likely due to inhibition of glycogen pool replenishment. Thus, the depletion of glycogen stores in the liver
might contribute to the impairment of hepatic glucose production during prolonged acute phase challenge. 相似文献
93.
94.
Rainer Voisard Tanja Krügers Barbara Reinhardt Bianca Vaida Regine Baur Tina Herter Anke Lüske Dorothea Weckermann Karl Weingärtner Wolfgang Rössler Vinzenz Hombach Thomas Mertens 《BMC microbiology》2007,7(1):1-6
Background
The impact of infections with the human cytomegalovirus (HCMV) for the development of atherosclerosis and restenosis is still unclear. Both a clear correlation and no correlation at all have been reported in clinical, mostly serological studies. In our study we employed a human non-injury ex vivo organ culture model to investigate the effect of an in vitro permissive HCMV-infection on cell proliferation and neointimal hyperplasia for a period of 56 days.Results
During routine-nephrectomies parts of renal arteries from 71 patients were obtained and prepared as human organ cultures. Cell free HCMV infection was performed with the fibroblast adapted HCMV strain AD169, the endotheliotropic strain TB40E, and a clinical isolate (AN 365). After 3, 7, 14, 21, 28, 35, and 56 days in culture staining of HCMV-antigens was carried out and reactive cell proliferation and neointimal thickening were analysed. Successful HCMV-infection was accomplished with all three virus strains studied. During the first 21 days in organ culture no cell proliferation or neointimal hyperplasia was detected. At day 35 and day 56 moderate cell proliferation and neointimal hyperplasia was found both in HCMV-infected segments and mock infected controls. Neointimal hyperplasia in productively HCMV-infected segments was lower than in non infected at day 35 and day 56, but relatively higher after infection with the endotheliotropic TB40E in comparison with the two other strains.Conclusion
The data do not support the hypothesis that HCMV-infection triggers restenosis via a stimulatory effect on cell proliferation and neointimal hyperplasia in comparison to non infected controls. Interestingly however, even after lytic infection, a virus strain specific difference was observed. 相似文献95.
Jesus Ronald Ferreira Santos Ana Nunes Nandyara Bianca dos Santos Jeannie Nascimento Melo Francisco Tiago Vasconcelos 《Systematic parasitology》2022,99(6):761-769
Systematic Parasitology - Nematodes collected from the stomach and large intestine of Rhinoclemmys punctularia (Daudin) from the eastern Amazon, Brazil, are assigned to a new genus, Vogtnema n.... 相似文献
96.
97.
Noelia Inés Burgardt Andreas Schmidt Annika Manns Alexandra Schutkowski Günther Jahreis Yi-Jan Lin Bianca Schulze Antonia Masch Christian Lücke Matthias Weiwad 《The Journal of biological chemistry》2015,290(27):16708-16722
Recently we have shown that the peptidyl-prolyl cis/trans isomerase parvulin 17 (Par17) interacts with tubulin in a GTP-dependent manner, thereby promoting the formation of microtubules. Microtubule assembly is regulated by Ca2+-loaded calmodulin (Ca2+/CaM) both in the intact cell and under in vitro conditions via direct interaction with microtubule-associated proteins. Here we provide the first evidence that Ca2+/CaM interacts also with Par17 in a physiologically relevant way, thus preventing Par17-promoted microtubule assembly. In contrast, parvulin 14 (Par14), which lacks only the first 25 N-terminal residues of the Par17 sequence, does not interact with Ca2+/CaM, indicating that this interaction is exclusive for Par17. Pulldown experiments and chemical shift perturbation analysis with 15N-labeled Par17 furthermore confirmed that calmodulin (CaM) interacts in a Ca2+-dependent manner with the Par17 N terminus. The reverse experiment with 15N-labeled Ca2+/CaM demonstrated that the N-terminal Par17 segment binds to both CaM lobes simultaneously, indicating that Ca2+/CaM undergoes a conformational change to form a binding channel between its two lobes, apparently similar to the structure of the CaM-smMLCK796–815 complex. In vitro tubulin polymerization assays furthermore showed that Ca2+/CaM completely suppresses Par17-promoted microtubule assembly. The results imply that Ca2+/CaM binding to the N-terminal segment of Par17 causes steric hindrance of the Par17 active site, thus interfering with the Par17/tubulin interaction. This Ca2+/CaM-mediated control of Par17-assisted microtubule assembly may provide a mechanism that couples Ca2+ signaling with microtubule function. 相似文献
98.
99.
100.
Geometric morphometrics throws light on evolution of the subterranean catfish Rhamdiopsis krugi (Teleostei: Siluriformes: Heptapteridae) in eastern Brazil 下载免费PDF全文
Maria Elina Bichuette Bianca Rantin Erika Hingst‐Zaher Eleonora Trajano 《Biological journal of the Linnean Society. Linnean Society of London》2015,114(1):136-151
Rhamdiopsis krugi is a highly specialized troglobitic (exclusively subterranean) catfish from phreatic water bodies of caves located within two separated metasedimentary basins in the region of Chapada Diamantina, Bahia state, Brazil. In order to test the hypothesis of isolation with differentiation of the groups from the Una‐Utinga and Irecê metasedimentary basins, we compared five populations among themselves and with an epigean species of Rhamdiopsis. This was accomplished using geometric morphometrics, a powerful tool for detecting differences in body shape at population and species levels. All studied samples differed significantly from each other, the epigean sample being the most distinct and the Una Basin populations clustering together. Geological and hydrological barriers explain the differences among the subterranean populations. We discuss our results together with the autapomorphies found in R. krugi, which validate its monophyly. These results imply an old age for the R. krugi clade, more than 10 Myr; alternative hypotheses are also presented. We propose a two‐step vertical colonization model of the subterranean habitat through the hyporheic zone by an epigean ancestral, with a progressive acquisition of the autapomorphies characterizing R. krugi. For conservation purposes, the two differentiated sets of populations should be considered and referred to as R. krugi ‘Una morphotype’ and R. krugi ‘Irecê morphotype’. © 2014 The Linnean Society of London, Biological Journal of the Linnean Society, 2014, 114 , 136–151. 相似文献