全文获取类型
收费全文 | 1187篇 |
免费 | 73篇 |
国内免费 | 1篇 |
专业分类
1261篇 |
出版年
2023年 | 4篇 |
2022年 | 11篇 |
2021年 | 17篇 |
2020年 | 6篇 |
2019年 | 11篇 |
2018年 | 23篇 |
2017年 | 14篇 |
2016年 | 33篇 |
2015年 | 50篇 |
2014年 | 61篇 |
2013年 | 68篇 |
2012年 | 88篇 |
2011年 | 90篇 |
2010年 | 79篇 |
2009年 | 52篇 |
2008年 | 75篇 |
2007年 | 74篇 |
2006年 | 64篇 |
2005年 | 60篇 |
2004年 | 58篇 |
2003年 | 65篇 |
2002年 | 59篇 |
2001年 | 12篇 |
2000年 | 9篇 |
1999年 | 12篇 |
1998年 | 17篇 |
1997年 | 10篇 |
1996年 | 7篇 |
1995年 | 7篇 |
1994年 | 6篇 |
1993年 | 13篇 |
1992年 | 4篇 |
1991年 | 4篇 |
1990年 | 3篇 |
1989年 | 10篇 |
1988年 | 6篇 |
1987年 | 4篇 |
1986年 | 5篇 |
1985年 | 8篇 |
1984年 | 9篇 |
1982年 | 8篇 |
1981年 | 4篇 |
1980年 | 3篇 |
1979年 | 4篇 |
1978年 | 3篇 |
1977年 | 4篇 |
1976年 | 3篇 |
1975年 | 3篇 |
1967年 | 2篇 |
1957年 | 2篇 |
排序方式: 共有1261条查询结果,搜索用时 0 毫秒
91.
A novel method to monitor insulin-stimulated GTP-loading of Rab11a in cardiomyocytes 总被引:1,自引:0,他引:1
As a member of the Rab small GTPase family, Rab11a has been shown to be involved in different vesicle trafficking processes. In earlier work we identified Rab11a to be present in GLUT4-containing vesicles after insulin stimulation and showed its involvement in insulin-dependent glucose uptake. However, it remained elusive if Rab11a is directly activated by the insulin signalling cascade and at which step a potential activation occurs. To examine the GTP-loading of Rab11a, we introduced a biotinylated GTP-analog into H9c2-hIR cells, transiently overexpressing HA-tagged Rab11a, and measured its binding to the GTPase after insulin stimulation. We observed that Rab11a is transiently GTP-loaded after insulin stimulation with a 2.3 (+/-0.3) fold activation (n=5), reaching its maximum after 4 min and declining back to basal after additional 2 min. The activation of Rab11a is phosphatidylinositol 3-kinase (PI3-kinase) dependent and downstream of Akt, as shown by in vitro knockdown of this kinase. These data show that Rab11a is directly activated by insulin and represents an element of the GLUT4 trafficking machinery. 相似文献
92.
93.
Ingeborg Teppner Sonja Becker Martin Hrabé de Angelis Achim Gossler Johannes Beckers 《BMC developmental biology》2007,7(1):68
Background
Expression of the mouse Delta-like 1 (Dll1) gene in the presomitic mesoderm and in the caudal halves of somites of the developing embryo is required for the formation of epithelial somites and for the maintenance of caudal somite identity, respectively. The rostro-caudal polarity of somites is initiated early on within the presomitic mesoderm in nascent somites. Here we have investigated the requirement of restricted Dll1 expression in caudal somite compartments for the maintenance of rostro-caudal somite polarity and the morphogenesis of the axial skeleton. We did this by overexpressing a functional copy of the Dll1 gene throughout the paraxial mesoderm, in particular in anterior somite compartments, during somitogenesis in transgenic mice. 相似文献94.
Jarutat T Nickels C Frisch C Stellmacher F Hofig KP Knappik A Merz H 《Biological chemistry》2007,388(6):651-658
We describe the direct isolation of specific antibodies on formalin-fixed, paraffin-embedded (FFPE) tissue. The technique involves subtractive selection of a large and highly diverse combinatorial human antibody phage library (HuCAL) on lymphocyte FFPE tissue sections. Tissue sections from normal human tonsil tissue were used to deplete the library of binders to most housekeeping proteins. Mantle-cell lymphoma tissue was used for positive selection and enrichment of mantle cell or tumor-specific antibody phage. We established a high-throughput immunohistochemical method for screening of antibody clones selected from FFPE tissue. One recombinant antibody showed specific staining for interfollicular and mantle cells in FFPE tissue. Immunoprecipitation with this antibody and subsequent mass spectrometric analysis revealed specificity for vimentin. 相似文献
95.
Synthesis and in vitro hydroxyapatite binding of peptides conjugated to calcium-binding moieties 总被引:1,自引:0,他引:1
To confer bone-binding properties to proteins and other biological agents that lack specific targeting capacity, model peptide-based molecules were synthesized containing poly(aspartic acid), poly(glutamic acid), or a bisphosphonate (pamidronate). These motifs have well-documented affinities to hydroxyapatite, a property desirable for the targeting of molecules to bone for drug delivery and tissue engineering applications. Model peptides of increasing molecular mass (5-33 amino acids) were directly conjugated to eight aspartic acids (Asp8), eight glutamic acids (Glu8), or pamidronate, purified by high-performance liquid chromatography, and characterized by matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectroscopy. The modified peptides were incubated with hydroxyapatite in phosphate-buffered saline at physiological conditions over 24 h. This study revealed a significant amount (>90%) of conjugated peptides adsorbed to the hydroxyapatite as compared to unmodified peptides (<5%). It was found that while there were significant differences between the different hydroxyapatite-binding and control groups for all time points, the size of the peptide had no statistical effect on peptide-hydroxyapatite binding. These results demonstrate that bisphosphonate and oligopeptide conjugates hold great promise for the development of new bioactive molecules for bone-specific applications. 相似文献
96.
97.
Jan Gundlach Achim Dickmanns Kathrin Schr?der-Tittmann Piotr Neumann Jan Kaesler Jan Kampf Christina Herzberg Elke Hammer Frank Schwede Volkhard Kaever Kai Tittmann J?rg Stülke Ralf Ficner 《The Journal of biological chemistry》2015,290(5):3069-3080
The cyclic dimeric AMP nucleotide c-di-AMP is an essential second messenger in Bacillus subtilis. We have identified the protein DarA as one of the prominent c-di-AMP receptors in B. subtilis. Crystal structure analysis shows that DarA is highly homologous to PII signal transducer proteins. In contrast to PII proteins, the functionally important B- and T-loops are swapped with respect to their size. DarA is a homotrimer that binds three molecules of c-di-AMP, each in a pocket located between two subunits. We demonstrate that DarA is capable to bind c-di-AMP and with lower affinity cyclic GMP-AMP (3′3′-cGAMP) but not c-di-GMP or 2′3′-cGAMP. Consistently the crystal structure shows that within the ligand-binding pocket only one adenine is highly specifically recognized, whereas the pocket for the other adenine appears to be promiscuous. Comparison with a homologous ligand-free DarA structure reveals that c-di-AMP binding is accompanied by conformational changes of both the fold and the position of the B-loop in DarA. 相似文献
98.
Thomas O. Eichmann Lukas Grumet Ulrike Taschler Jürgen Hartler Christoph Heier Aaron Woblistin Laura Pajed Manfred Kollroser Gerald Rechberger Gerhard G. Thallinger Rudolf Zechner Günter Haemmerle Robert Zimmermann Achim Lass 《Journal of lipid research》2015,56(10):1972-1984
Lipid droplets (LDs) of hepatic stellate cells (HSCs) contain large amounts of vitamin A [in the form of retinyl esters (REs)] as well as other neutral lipids such as TGs. During times of insufficient vitamin A availability, RE stores are mobilized to ensure a constant supply to the body. To date, little is known about the enzymes responsible for the hydrolysis of neutral lipid esters, in particular of REs, in HSCs. In this study, we aimed to identify LD-associated neutral lipid hydrolases by a proteomic approach using the rat stellate cell line HSC-T6. First, we loaded cells with retinol and FAs to promote lipid synthesis and deposition within LDs. Then, LDs were isolated and lipid composition and the LD proteome were analyzed. Among other proteins, we found perilipin 2, adipose TG lipase (ATGL), and comparative gene identification-58 (CGI-58), known and established LD proteins. Bioinformatic search of the LD proteome for α/β-hydrolase fold-containing proteins revealed no yet uncharacterized neutral lipid hydrolases. In in vitro activity assays, we show that rat (r)ATGL, coactivated by rat (r)CGI-58, efficiently hydrolyzes TGs and REs. These findings suggest that rATGL and rCGI-58 are LD-resident proteins in HSCs and participate in the mobilization of both REs and TGs. 相似文献
99.
100.
Franziska Volland-Voigt Achim Br?uning Oswaldo Ganzhi Thorsten Peters Hector Maza 《Trees - Structure and Function》2011,25(1):39-48
Stem diameter increments of the broadleaved deciduous tree species Tabebuia chrysantha were measured with high-resolution dendrometers in a tropical lower montane forest and in a dry forest in southern Ecuador,
the latter showing a distinct dry season. Those analyses were complemented by wood anatomical studies on regularly collected
microcores to determine the season of active cambial growth and the time of formation of annual growth boundaries. The length
of the cambial active period varied between 3 and 7 months at the tropical lower montane forest and 2 and 4 months in the
dry forest, respectively. During dry days, amplitudes of daily stem diameter variations correlated with vapour pressure deficit.
During October and November, inter-annual climate variations may lead to dry and sunny conditions in the tropical lower montane
forest, causing water deficit and stem diameter shrinkage in T. chrysantha. The results of the climate–growth analysis show a positive relationship between tree growth and rainfall as well as vapour
pressure deficit in certain periods of the year, indicating that rainfall plays a major role for tree growth. 相似文献