全文获取类型
收费全文 | 638篇 |
免费 | 38篇 |
国内免费 | 2篇 |
出版年
2023年 | 10篇 |
2022年 | 12篇 |
2021年 | 17篇 |
2020年 | 10篇 |
2019年 | 10篇 |
2018年 | 14篇 |
2017年 | 8篇 |
2016年 | 23篇 |
2015年 | 28篇 |
2014年 | 26篇 |
2013年 | 42篇 |
2012年 | 48篇 |
2011年 | 74篇 |
2010年 | 46篇 |
2009年 | 31篇 |
2008年 | 50篇 |
2007年 | 53篇 |
2006年 | 31篇 |
2005年 | 36篇 |
2004年 | 33篇 |
2003年 | 14篇 |
2002年 | 21篇 |
2001年 | 4篇 |
2000年 | 2篇 |
1999年 | 1篇 |
1998年 | 3篇 |
1997年 | 3篇 |
1996年 | 4篇 |
1995年 | 6篇 |
1994年 | 2篇 |
1993年 | 4篇 |
1992年 | 1篇 |
1991年 | 1篇 |
1990年 | 2篇 |
1988年 | 2篇 |
1981年 | 2篇 |
1979年 | 1篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1963年 | 1篇 |
排序方式: 共有678条查询结果,搜索用时 31 毫秒
531.
532.
533.
Aphrodite Tsaballa Konstantinos Pasentsis Nikos Darzentas Athanasios S Tsaftaris 《BMC plant biology》2011,11(1):46
Background
Grafting is a widely used technique contributing to sustainable and ecological production of many vegetables, but important fruit quality characters such as taste, aroma, texture and shape are known for years to be affected by grafting in important vegetables species including pepper. From all the characters affected, fruit shape is the most easily observed and measured. From research in tomato, fruit shape is known to be controlled by many QTLs but only few of them have larger effect on fruit shape variance. In this study we used pepper cultivars with different fruit shape to study the role of a pepper Ovate-like gene, CaOvate, which encodes a negative regulator protein that brings significant changes in tomato fruit shape. 相似文献534.
Introduction
To assess the efficacy and safety of the interleukin-1 receptor (IL-1R) inhibitor anakinra in adult patients with refractory Still's disease.Methods
Twenty-five patients (13 males and 12 females, median age 32 years, median disease duration seven months) with Still's disease were treated with subcutaneous injections of anakinra (100 mg/day). Treatment was given as adjunct therapy in 16 patients and as standalone in 9 patients for a median time of 15 months (range 1.5-71). The clinical and laboratory parameters during follow-up were recorded.Results
In 84% of patients the clinical activity resolved completely within a few days (median time 0.2 months), and response was maintained until the last visit in all but one patient. A complete response of all disease-related symptoms (clinical and laboratory) occurred subsequently within a median time of three months in 80% of patients. A partial clinical and laboratory improvement was shown in 12% and 16% of patients, respectively. The Visualized Analogue Scale and Health Assessment Questionnaire scores significantly decreased during treatment. The proportion of patients achieving the American College of Rheumatology 20 (ACR20) score (20% improvement) was 82% at one month and improved to 100% at one year. The mean oral corticosteroid dose was significantly reduced at each visit. Anakinra was discontinued due to unresponsiveness in one patient and due to relapsing disease in another. Treatment was also withdrawn in three patients with severe skin reactions (urticaria). Seven patients experienced an infection during follow-up.Conclusions
The rapid and sustained response in the majority of our patients encourages the use of anakinra in adults with Still's disease. 相似文献535.
Kousathanas A Oliver F Halligan DL Keightley PD 《Molecular biology and evolution》2011,28(3):1183-1191
During the past two decades, evidence has accumulated of adaptive evolution within protein-coding genes in a variety of species. However, with the exception of Drosophila and humans, little is known about the extent of adaptive evolution in noncoding DNA. Here, we study regions upstream and downstream of protein-coding genes in the house mouse Mus musculus castaneus, a species that has a much larger effective population size (N(e)) than humans. We analyze polymorphism data for 78 genes from 15 wild-caught M. m. castaneus individuals and divergence to a closely related species, Mus famulus. We find high levels of nucleotide diversity and moderate levels of selective constraint in upstream and downstream regions compared with nonsynonymous sites of protein-coding genes. From the polymorphism data, we estimate the distribution of fitness effects (DFE) of new mutations and infer that most new mutations in upstream and downstream regions behave as effectively neutral and that only a small fraction is strongly negatively selected. We also estimate the fraction of substitutions that have been driven to fixation by positive selection (α) and the ratio of adaptive to neutral divergence (ω(α)). We find that α for upstream and downstream regions (~ 10%) is much lower than α for nonsynonymous sites (~ 50%). However, ω(α) estimates are very similar for nonsynonymous sites (~ 10%) and upstream and downstream regions (~ 5%). We conclude that negative selection operating in upstream and downstream regions of M. m. castaneus is weak and that the low values of α for upstream and downstream regions relative to nonsynonymous sites are most likely due to the presence of a higher proportion of neutrally evolving sites and not due to lower absolute rates of adaptive substitution. 相似文献
536.
537.
High energy prices, depletion of crude oil supplies, and price imbalance created by the increasing demand of plant oils or
animal fat for biodiesel and specific lipid derivatives such as lubricants, adhesives, and plastics have given rise to heated
debates on land-use practices and to environmental concerns about oil production strategies. However, commercialization of
microbial oils with similar composition and energy value to plant and animal oils could have many advantages, such as being
non-competitive with food, having shorter process cycle and being independent of season and climate factors. This review focuses
on the ongoing research on different oleaginous yeasts producing high added value lipids and on the prospects of such microbial
oils to be used in different biotechnological processes and applications. It covers the basic biochemical mechanisms of lipid
synthesis and accumulation in these organisms, along with the latest insights on the metabolic processes involved. The key
elements of lipid accumulation, the mechanisms suspected to confer the oleaginous character of the cell, and the potential
metabolic routes enhancing lipid production are also extensively discussed. 相似文献
538.
Dimitropoulos N Papakyriakou A Dalkas GA Chasapis CT Poulas K Spyroulias GA 《Proteins》2011,79(1):142-152
Based on the crystal structure of the extracellular domain (ECD) of the mouse nicotinic acetylcholine receptor (nAChR) alpha1 subunit bound to α-bungarotoxin (α-Btx) we have generated in silico models of the human nAChR α1 bound to α-Btx and α-cobratoxin (α-Cbtx), both in the presence and in the absence of the N-linked carbohydrate chain. To gain further insight into the structural role of glycosylation molecular dynamics (MD) simulations were carried out in explicit solvent so as to compare the conformational dynamics of the binding interface between nAChR α1 and the two toxins. An interesting observation during the course of the MD simulations is the strengthening of the receptor-toxin interaction in the presence of the carbohydrate chain, mediated through a shift in the position of the sugars towards the bound toxin. Critical protein-sugar interactions implicate residues Ser187 and Trp184 of nAChR and Thr6, Ser9, and Thr15 of α-Btx, as well as Thr6 and Pro7 of α-Cbtx. Analysis of the predicted residue-specific intermolecular interactions is intended to inspire biophysical studies on the functional role of glycosylation in the gating mechanism. 相似文献
539.
Bellen HJ Levis RW He Y Carlson JW Evans-Holm M Bae E Kim J Metaxakis A Savakis C Schulze KL Hoskins RA Spradling AC 《Genetics》2011,188(3):731-743
The Drosophila Gene Disruption Project (GDP) has created a public collection of mutant strains containing single transposon insertions associated with different genes. These strains often disrupt gene function directly, allow production of new alleles, and have many other applications for analyzing gene function. Here we describe the addition of ~7600 new strains, which were selected from >140,000 additional P or piggyBac element integrations and 12,500 newly generated insertions of the Minos transposon. These additions nearly double the size of the collection and increase the number of tagged genes to at least 9440, approximately two-thirds of all annotated protein-coding genes. We also compare the site specificity of the three major transposons used in the project. All three elements insert only rarely within many Polycomb-regulated regions, a property that may contribute to the origin of "transposon-free regions" (TFRs) in metazoan genomes. Within other genomic regions, Minos transposes essentially at random, whereas P or piggyBac elements display distinctive hotspots and coldspots. P elements, as previously shown, have a strong preference for promoters. In contrast, piggyBac site selectivity suggests that it has evolved to reduce deleterious and increase adaptive changes in host gene expression. The propensity of Minos to integrate broadly makes possible a hybrid finishing strategy for the project that will bring >95% of Drosophila genes under experimental control within their native genomic contexts. 相似文献
540.
Georgopoulos NA Rottstein L Tsekouras A Theodoropoulou A Koukkou E Mylonas P Polykarpou G Lampropoulou E Iconomou G Leglise M Vagenakis AG Markou KB 《Steroids》2011,76(4):353-357