全文获取类型
收费全文 | 309篇 |
免费 | 32篇 |
国内免费 | 1篇 |
出版年
2022年 | 2篇 |
2021年 | 3篇 |
2020年 | 2篇 |
2019年 | 3篇 |
2017年 | 4篇 |
2016年 | 8篇 |
2015年 | 13篇 |
2014年 | 11篇 |
2013年 | 7篇 |
2012年 | 13篇 |
2011年 | 15篇 |
2010年 | 12篇 |
2009年 | 15篇 |
2008年 | 11篇 |
2007年 | 20篇 |
2006年 | 10篇 |
2005年 | 13篇 |
2004年 | 15篇 |
2003年 | 11篇 |
2002年 | 10篇 |
2001年 | 12篇 |
2000年 | 10篇 |
1999年 | 4篇 |
1998年 | 7篇 |
1997年 | 4篇 |
1996年 | 6篇 |
1995年 | 6篇 |
1994年 | 4篇 |
1993年 | 5篇 |
1992年 | 5篇 |
1990年 | 5篇 |
1989年 | 5篇 |
1988年 | 2篇 |
1987年 | 2篇 |
1986年 | 3篇 |
1985年 | 6篇 |
1984年 | 2篇 |
1983年 | 6篇 |
1982年 | 2篇 |
1981年 | 3篇 |
1978年 | 3篇 |
1977年 | 6篇 |
1976年 | 4篇 |
1975年 | 2篇 |
1974年 | 5篇 |
1973年 | 2篇 |
1971年 | 2篇 |
1968年 | 2篇 |
1967年 | 3篇 |
1964年 | 2篇 |
排序方式: 共有342条查询结果,搜索用时 234 毫秒
71.
72.
73.
Background
Pathway-targeted or low-density arrays are used more and more frequently in biomedical research, particularly those arrays that are based on quantitative real-time PCR. Typical QPCR arrays contain 96-1024 primer pairs or probes, and they bring with it the promise of being able to reliably measure differences in target levels without the need to establish absolute standard curves for each and every target. To achieve reliable quantification all primer pairs or array probes must perform with the same efficiency. 相似文献74.
Understanding the effects of trophic status and dissolved organic carbon concentration (DOC) on lake carbon cycling is essential
for accurate ecosystem carbon models. Using isotopically labelled substrates we assessed spatial and temporal variability
in bacterial respiration (BR) and algal primary production (PP) in two trophically, morphometrically and hydrologically different
basins in Loch Lomond, a large temperate lake in Scotland. GIS modelling was used to construct a whole lake balance for bacterial
production/respiration and PP, and from this the proportion of heterotrophy fuelled by allochthonous carbon was estimated.
We tested the hypotheses that trophic status and DOC concentration affect the balance between PP and BR and examined which
is the more significant driving factor. Additionally we estimated the percentage of BR that is fuelled by terrestrial carbon.
PP varied seasonally and showed inter-basin homogeneity. BR was greatest in the mesotrophic south basin in autumn, which corresponded
to measured peak DOC input, though over an annual cycle no relationship was observed between BR and DOC concentration. The
PP:BR ratio was 0.37 ± 0.30 and 0.3 ± 0.45 in the north and south basins, respectively, assuming a bacterial growth efficiency
of 0.1. We have found that allochthonous carbon potentially supports a substantial quantity of pelagic production, even during
periods of high photosynthesis. Less productive systems are thought to be dominated by heterotrophic processes. However, we
have found that the mesotrophic basin of a large lake to be as heterotrophic as its neighbouring oligotrophic basin, an observation
that has implications for our understanding of modelling of the role of lakes in linking the terrestrial-atmospheric carbon
cycle. 相似文献
75.
76.
The results presented here demonstrate that protein kinase D (PKD) and PKCeta transiently coexpressed in COS-7 cells form complexes that can be immunoprecipitated from cell lysates using specific antisera to PKD or PKCeta. The presence of PKCeta in PKD immune complexes was initially detected by in vitro kinase assays which reveal the presence of an 80-kDa phosphorylated band in addition to the 110-kDa band corresponding to autophosphorylated PKD. The association between PKD and PKCeta was further verified by Western blot analysis and peptide phosphorylation assays that exploited the distinct substrate specificity between PKCs and PKD. By the same criteria, PKD formed complexes only very weakly with PKCepsilon, and did not bind PKCzeta. When PKCeta was coexpressed with PKD mutants containing either complete or partial deletions of the PH domain, both PKCeta immunoreactivity and PKC activity in PKD immunoprecipitates were sharply reduced. In contrast, deletion of an amino-terminal portion of the molecule, either cysteine-rich region, or the entire cysteine-rich domain did not interfere with the association of PKD with PKCeta. Furthermore, a glutathione S-transferase-PKDPH fusion protein bound preferentially to PKCeta. These results indicate that the PKD PH domain can discriminate between closely related structures of a single enzyme family, e.g. novel PKCs epsilon and eta, thereby revealing a previously undetected degree of specificity among protein-protein interactions mediated by PH domains. 相似文献
77.
Waldron RT Rey O Zhukova E Rozengurt E 《The Journal of biological chemistry》2004,279(26):27482-27493
Oxidative stress induced by cell treatments with H(2)O(2) activates protein kinase D (PKD) via a protein kinase C (PKC)-dependent signal transduction pathway (Waldron, R. T., and Rozengurt, E. (2000) J. Biol. Chem. 275, 17114-17121). Here we show that oxidative stress induces PKC-dependent activation loop Ser(744) and Ser(748) phosphorylation to mediate dose- and time-dependent activation of PKD, both endogenously expressed in Swiss 3T3 cells and stably overexpressed in Swiss 3T3-GFP.PKD cells. Although oxidative stress induced PKD activation loop phosphorylation and activation with identical kinetics, both were dose-dependently blocked by preincubation of cells with selective inhibitors of PKC (GF109203X and G?6983) or c-Src (PP2). Inhibition of Src tyrosine kinase activity eliminated oxidative stress-induced direct PKD tyrosine phosphorylation, but only partially attenuated activation loop phosphorylation and activation. Mutation of a putative tyrosine phosphorylation site on PKD, Tyr(469) to phenylalanine, had no effect on its activation by oxidative stress in transfected COS-7 cells. Similarly, a mutant with Tyr(469) replaced by aspartic acid had increased basal activity but was also further activated by oxidative stress. Thus, PKD tyrosine phosphorylation at this site neither produced full activation by itself nor was required for oxidative stress-induced activation mediated by activation loop phosphorylation. In addition to PKD activation, activation loop phosphorylation in response to oxidative stress also redistributed activated PKD to cell nuclei, as revealed by PKD indirect immunofluorescence, imaging of a PKD-green fluorescent protein fusion construct (GFP-PKD), and analysis of nuclear pellets. Cell preincubation with G?6983 strongly diminished H(2)O(2)-induced nuclear relocalization of GFP-PKD. Taken together, these results indicate that PKC-mediated PKD Ser(744) and Ser(748) phosphorylation induced by oxidative stress integrates PKD activation with redistribution to the nucleus. 相似文献
78.
Comparative analysis of the zeta-crystallin/quinone reductase gene in guinea pig and mouse 总被引:1,自引:0,他引:1
Gonzalez P; Hernandez-Calzadilla C; Rao PV; Rodriguez IR; Zigler JS Jr; Borras T 《Molecular biology and evolution》1994,11(2):305-315
zeta-Crystallin is a novel nicotinamide adenine dinucleotide
phosphate:quinone reductase, present at enzymatic levels in various tissues
of different species, which is highly expressed in the lens of some
hystricomorph rodents and camelids. We report here the complementary DNA
(cDNA) cloning of zeta-crystallin from liver libraries in guinea pig (Cavia
porcellus), where zeta-crystallin is highly expressed in the lens, and in
the laboratory mouse (Mus musculus), where expression in the lens occurs
only at enzymatic levels. A 5' untranslated sequence different from the one
previously reported for the guinea pig lens cDNA was found in these clones.
We also report the isolation of genomic clones including the complete
guinea pig zeta-crystallin gene and the 5' region of this gene in mouse.
These results show the presence of two promoters in the guinea pig
zeta-crystallin gene, one responsible for expression at enzymatic levels
and the other responsible for the high expression in the lens. The guinea
pig lens promoter is not present in the mouse gene. This is the first
example in which the recruitment of an enzyme as a lens crystallin can be
explained by the acquisition of an alternative lens- specific promoter.
相似文献
79.
80.
Waldron G 《BMJ (Clinical research ed.)》2000,320(7244):1276-1277