全文获取类型
收费全文 | 1254篇 |
免费 | 113篇 |
出版年
2023年 | 15篇 |
2022年 | 15篇 |
2021年 | 42篇 |
2020年 | 29篇 |
2019年 | 39篇 |
2018年 | 51篇 |
2017年 | 39篇 |
2016年 | 47篇 |
2015年 | 101篇 |
2014年 | 72篇 |
2013年 | 108篇 |
2012年 | 136篇 |
2011年 | 115篇 |
2010年 | 78篇 |
2009年 | 55篇 |
2008年 | 64篇 |
2007年 | 66篇 |
2006年 | 55篇 |
2005年 | 45篇 |
2004年 | 36篇 |
2003年 | 29篇 |
2002年 | 30篇 |
2001年 | 11篇 |
2000年 | 9篇 |
1999年 | 8篇 |
1998年 | 7篇 |
1997年 | 5篇 |
1996年 | 3篇 |
1995年 | 4篇 |
1994年 | 2篇 |
1993年 | 4篇 |
1992年 | 2篇 |
1991年 | 2篇 |
1989年 | 6篇 |
1988年 | 2篇 |
1987年 | 3篇 |
1986年 | 3篇 |
1984年 | 3篇 |
1983年 | 4篇 |
1981年 | 2篇 |
1980年 | 3篇 |
1978年 | 2篇 |
1976年 | 2篇 |
1974年 | 2篇 |
1972年 | 2篇 |
1969年 | 1篇 |
1960年 | 1篇 |
1958年 | 1篇 |
1956年 | 1篇 |
1955年 | 1篇 |
排序方式: 共有1367条查询结果,搜索用时 390 毫秒
181.
Sarah Schwarzer Lucie Kolacna Hella Lichtenberg-Fraté Hana Sychrova Jost Ludwig 《FEMS yeast research》2008,8(3):405-413
It has been shown previously that heterologous expression of inwardly rectifying potassium channels (K+-channels) from plants and mammals in K+-transport defective yeast mutants can restore the ability of growth in media with low [K+]. In this study, the functional expression of an outward rectifying mammalian K+-channel in yeast is presented for the first time. The outward-rectifying mammalian neuronal K+-channel rat ether à go-go channel 1 (rEAG1, Kv 10.1) was expressed in yeast (Saccharomyces cerevisiae) strains lacking the endogenous K+-uptake systems and/or alkali-metal-cation efflux systems. It was found that a truncated channel version, lacking almost the complete intracellular N-terminus (rEAG1 Delta 190) but not the full-length rEAG1, partially complemented the growth defect of K+-uptake mutant cells (trk1,2 Delta tok1 Delta) in media containing low K+ concentrations. The expression of rEAG1 Delta 190 in a strain lacking the cation efflux systems (nha1 Delta ena1-4 Delta) increased the sensitivity to high monovalent cation concentrations. Both phenotypes were observed, when rEAG1 Delta 190 was expressed in a trk1,2 Delta and nha1, ena1-4 Delta mutant strain. In the presence of K+-channel blockers (Cs+, Ba2+ and quinidine), the growth advantage of rEAG1 Delta 190 expressing trk1,2 tok1 Delta cells disappeared, indicating its dependence on functional rEAG1 channels. The results demonstrate that S. cerevisiae is a suitable expression system even for voltage-gated outward-rectifying mammalian K+-channels. 相似文献
182.
CE-SSCP and CE-FLA, simple and high-throughput alternatives for fungal diversity studies 总被引:2,自引:0,他引:2
Zinger L Gury J Alibeu O Rioux D Gielly L Sage L Pompanon F Geremia RA 《Journal of microbiological methods》2008,72(1):42-53
Fungal communities are key components of soil, but the study of their ecological significance is limited by a lack of appropriated methods. For instance, the assessment of fungi occurrence and spatio-temporal variation in soil requires the analysis of a large number of samples. The molecular signature methods provide a useful tool to monitor these microbial communities and can be easily adapted to capillary electrophoresis (CE) allowing high-throughput studies. Here we assess the suitability of CE-FLA (Fragment Length Polymorphism, denaturing conditions) and CE-SSCP (Single-Stranded Conformation Polymorphism, native conditions) applied to environmental studies since they require a short molecular marker and no post-PCR treatments. We amplified the ITS1 region from 22 fungal strains isolated from an alpine ecosystem and from total genomic DNA of alpine and infiltration basin soils. The CE-FLA and CE-SSCP separated 17 and 15 peaks respectively from a mixture of 19 strains. For the alpine soil-metagenomic DNA, the FLA displayed more peaks than the SSCP and the converse result was found for infiltration basin sediments. We concluded that CE-FLA and CE-SSCP of ITS1 region provided complementary information. In order to improve CE-SSCP sensitivity, we tested its resolution according to migration temperature and found 32 degrees C to be optimal. Because of their simplicity, quickness and reproducibility, we found that these two methods were promising for high-throughput studies of soil fungal communities. 相似文献
183.
Jin P. Szatkiewicz Glen L. Beane Yueming Ding Lucie Hutchins Fernando Pardo-Manuel de Villena Gary A. Churchill 《Mammalian genome》2008,19(3):199-208
We have created a high-density SNP resource encompassing 7.87 million polymorphic loci across 49 inbred mouse strains of the
laboratory mouse by combining data available from public databases and training a hidden Markov model to impute missing genotypes
in the combined data. The strong linkage disequilibrium found in dense sets of SNP markers in the laboratory mouse provides
the basis for accurate imputation. Using genotypes from eight independent SNP resources, we empirically validated the quality
of the imputed genotypes and demonstrated that they are highly reliable for most inbred strains. The imputed SNP resource
will be useful for studies of natural variation and complex traits. It will facilitate association study designs by providing
high-density SNP genotypes for large numbers of mouse strains. We anticipate that this resource will continue to evolve as
new genotype data become available for laboratory mouse strains. The data are available for bulk download or query at /.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
184.
Since proteins play crucial roles in all biological processes, the finely tuned equilibrium between their synthesis and degradation regulates cellular homeostasis. Controlling the quality of proteome informational content is essential for cell survival and function. After initial synthesis, membrane and secretory proteins are modified, folded, and assembled in the endoplasmic reticulum, whereas other proteins are synthesized and processed in the cytosol. Cells have different protein quality control systems, the molecular chaperones, which help protein folding and stabilization, and the ubiquitin-proteasome system (UPS) and lysosomes, which degrade proteins. It has generally been assumed that UPS and lysosomes are regulated independently and serve distinct functions. The UPS degrades both cytosolic, nuclear proteins, and myofibrillar proteins, whereas the lysosomes degrade most membrane and extracellular proteins by endocytosis as well as cytosolic proteins and organelles via autophagy. Over the last two decades, the UPS has been increasingly recognized as a major system in several biological processes including cell proliferation, adaptation to stress and cell death. More recently, activation or impairment of the UPS has been reported in cardiac disease and recent evidence indicate that autophagy is a key mechanism to maintain cardiac structure and function. This review mainly focuses on the UPS and its various components in healthy and diseased heart, but also summarizes recent data suggesting parallel activation of the UPS and autophagy in cardiac disease. 相似文献
185.
Terrière E Sharman M Donaghey C Herrmann L Lonie J Strachan M Dougall N Best J Ebmeier KP Pimlott S Patterson J Wyper D 《Neurochemical research》2008,33(4):643-651
Five patients with Alzheimer’s disease and five healthy volunteers were examined by SPECT with the nicotinic receptor ligand
123I-5-IA-85380. Patients were scanned before and after 6 weeks of treatment with donepezil. Quantification by regions of interest
was reliable and the optimal normalisation procedure used cerebellar ratios. We found relative reductions in 5-IA binding
capacity in patients in thalamus, frontal and central regions of interest of approximately one standard deviation unit (Cohen’s
d = 1). Reductions in binding after treatment with the acetylcholinesterase inhibitor donepezil of the same magnitude occurred
in the brain stem. The study was clearly too small to confirm group differences, but it suggests that 5-IA can be used to
examine both group differences and treatment effects in patients with Alzheimer’s disease.
Special issue article in honor of George Fink. 相似文献
186.
187.
Mohamed Mohideen Quwailid Alison Hugill Neil Dear Lucie Vizor Sara Wells Emma Horner Shelly Fuller Jessica Weedon Hamish McMath Paul Woodman David Edwards David Campbell Susan Rodger Joanne Carey Ann Roberts Pete Glenister Zuzanna Lalanne Nick Parkinson Emma L. Coghill Richard McKeone Sam Cox John Willan Andy Greenfield David Keays Saffron Brady Nigel Spurr Ian Gray Jackie Hunter Steve D.M. Brown Roger D. Cox 《Mammalian genome》2004,15(8):585-591
N-ethyl-N-nitrosourea (ENU) introduces mutations throughout the mouse genome at relatively high efficiency. Successful high-throughput phenotype screens have been reported and alternative screens using sequence-based approaches have been proposed. For the purpose of generating an allelic series in selected genes by a sequence-based approach, we have constructed an archive of over 4000 DNA samples from individual F1 ENU-mutagenized mice paralleled by frozen sperm samples. Together with our previously reported archive, the total size now exceeds 6000 individuals. A gene-based screen of 27.4 Mbp of DNA, carried out using denaturing high-performance liquid chromatography (DHPLC), found a mutation rate of 1 in 1.01 Mbp of which 1 in 1.82 Mbp were potentially functional. Screening of whole or selected regions of genes on subsets of the archive has allowed us to identify 15 new alleles from 9 genes out of 15 tested. This is a powerful adjunct to conventional mutagenesis strategies and has the advantage of generating a variety of alleles with potentially different phenotypic outcomes that facilitate the investigation of gene function. It is now available to academic collaborators as a community resource. 相似文献
188.
The role of negatively charged amino acids in the F-loop of the β4 subunit in channel activation and desensitization was studied using the patch-clamp technique. The selected amino acids were changed to their neutral analogs via point mutations. Whole-cell currents were recorded in COS cells transiently transfected with the α3β4 nicotinic acetylcholine receptor. The application of acetylcholine (ACh), nicotine (Nic), cytisine (Cyt), carbamylcholine (CCh) and epibatidine (Epi) to cells clamped at − 40 mV produced inward currents which displayed biphasic desensitization. The EC50 of Epi and Nic were increased by a factor of 3-6 due to mutations D191N or D192N. Only Epi remained an agonist in the double-mutated receptors with EC50 increased 17-fold. The interaction of the receptors with the competitive antagonist (+)tubocurarine (TC) was weakened almost 3-fold in the double-mutated receptors. The mutations increased the proportion of the slower desensitization component and increased the response plateau, resulting in decreased receptor desensitization. The double mutation substantially accelerated the return from long-term desensitization induced by Epi. 相似文献
189.
Philippe Le Flèche Yolande Hauck Lucie Onteniente Agnès Prieur France Denoeud Vincent Ramisse Patricia Sylvestre Gary Benson Françoise Ramisse Gilles Vergnaud 《BMC microbiology》2001,1(1):2-14
Background
Some pathogenic bacteria are genetically very homogeneous, making strain discrimination difficult. In the last few years, tandem repeats have been increasingly recognized as markers of choice for genotyping a number of pathogens. The rapid evolution of these structures appears to contribute to the phenotypic flexibility of pathogens. The availability of whole-genome sequences has opened the way to the systematic evaluation of tandem repeats diversity and application to epidemiological studies. 相似文献190.