全文获取类型
收费全文 | 758篇 |
免费 | 30篇 |
出版年
2023年 | 2篇 |
2022年 | 10篇 |
2021年 | 18篇 |
2020年 | 12篇 |
2019年 | 16篇 |
2018年 | 34篇 |
2017年 | 16篇 |
2016年 | 34篇 |
2015年 | 50篇 |
2014年 | 56篇 |
2013年 | 68篇 |
2012年 | 63篇 |
2011年 | 63篇 |
2010年 | 25篇 |
2009年 | 32篇 |
2008年 | 42篇 |
2007年 | 51篇 |
2006年 | 53篇 |
2005年 | 35篇 |
2004年 | 34篇 |
2003年 | 20篇 |
2002年 | 27篇 |
2001年 | 2篇 |
2000年 | 1篇 |
1998年 | 4篇 |
1997年 | 3篇 |
1995年 | 3篇 |
1994年 | 1篇 |
1993年 | 2篇 |
1992年 | 4篇 |
1991年 | 2篇 |
1989年 | 1篇 |
1987年 | 1篇 |
1984年 | 1篇 |
1982年 | 1篇 |
1980年 | 1篇 |
排序方式: 共有788条查询结果,搜索用时 15 毫秒
81.
82.
Smorawinska M Szuplewska M Zaleski P Wawrzyniak P Maj A Plucienniczak A Bartosik D 《FEMS microbiology letters》2012,326(1):76-82
Klebsiella pneumoniae 287-w carries three small narrow host range (NHR) plasmids (pIGMS31, pIGMS32, and pIGRK), which could be maintained in several closely related species of Gammaproteobacteria, but not in Alphaproteobacteria. The plasmids contain different mobilization systems (MOB), whose activity in Escherichia coli was demonstrated in the presence of the helper transfer system originating from plasmid RK2. The MOBs of pIGMS31 and pIGMS32 are highly conserved in many bacterial plasmids (members of the MOB family), while the predicted MOB of pIGRK has a unique structure, encoding a protein similar to phage-related integrases. The MOBs of pIGMS31 and pIGMS32 enabled the transfer of heterologous replicons from E. coli into both gammaproteobacterial and alphaproteobacterial hosts, which suggests that these NHR plasmids contain broad host range MOB systems. Such plasmids therefore represent efficient carrier molecules, which may act as natural suicide vectors promoting the spread of diverse genetic information (including other types of mobile elements, e.g. resistance transposons) among evolutionarily distinct bacterial species. Thus, mobilizable NHR plasmids may play a much more important role in horizontal gene transfer than previously thought. 相似文献
83.
Sikorska E Iłowska E Wyrzykowski D Kwiatkowska A 《Biochimica et biophysica acta》2012,1818(12):2982-2993
In this work, the behavior of the neurohypophyseal hormones and their selected analogs was studied in the presence of membrane models in an attempt to correlate their activities with a distinct behavior at a level of peptide-lipid interactions. The influence of the peptides studied on the lipid acyl chain order was determined using FTIR spectroscopy. Conformational changes in the peptides upon binding to liposomes were examined using CD spectra. Attempts were also made to determine the binding parameters of the peptides to lipids using isothermal titration calorimetry (ITC). The results show unambiguously that the neurohyphophyseal hormone-like peptides interact with lipids, being a model of a eukaryotic cell membrane. Moreover, hydrophobic interactions between the peptides and liposomes are likely to determine the overall conformation of the peptide, especially below the temperature of the main phase transition (T(m)). Thus, the bulky and hydrophobic nature of the residues incorporated into the N-terminal part of neurohyphophyseal hormones is an important factor for both restriction of peptide mobility and the interaction of the analog with biomembrane. In turn, above T(m), the electrostatic interactions become also relevant for the conformation of the acyclic tail of the AVP-like peptides. 相似文献
84.
As guinea fowl age, their body weights and length of the esophagus and crop increased significantly, and relative length (cm x 100 g b.w(-1)) of the small intestine, caeca and total intestine decreased significantly (P < or = 0.05) in males and females. In addition, 52-week-old males had a significantly higher percentage length of rectum and heart weight, and females a significantly higher gizzard weight compared to 13-week-old birds. Compared to females, adult males differed significantly (P < or = 0.05) in the length of caeca and also in the proportion of the gizzard, proventriculus, heart and liver in total weight. 相似文献
85.
Cancer appears in the new form of cell life as a direct consequence of self-organising pre-cancer cells (dissipathogenic systems), whose further existence is disabled by extreme impairment of their metabolism. Life itself is the highest value, since instead of necrosis or apoptosis, the cellular system in an unfavourable environment can change its genetic identity provided that the improvement in its own metabolism leads to increased chaos by higher dissipation of matter and energy in its environment. Prolongation of human life has resulted by a longer period of old age which is favourable for self-organisation of dissipative neoplastic cells. Modern medicine has explained the relation of the cervical cancer to preterm births and to inadequate use of oral contraceptives and/or replacement, instead of supplementary, neurohormonal therapy. Therefore, as early as in the period of pregnancy reproductive cells should be protected due to their prime importance in the intergenerational passage of life. Disturbance of systemic autoregulation causes development of dissipathogenic state of cells. A single zygote, whose environment is also important for the future development of the next two generations that are initiated with its formation, defines the unique identity of each person, whose life is determined by free will and neoplasms. 相似文献
86.
87.
Waszkiewicz N Szajda SD Zalewska A Szulc A Kępka A Minarowska A Wojewódzka-Żelezniakowicz M Konarzewska B Chojnowska S Ladny JR Zwierz K 《Folia histochemica et cytobiologica / Polish Academy of Sciences, Polish Histochemical and Cytochemical Society》2012,50(1):1-11
The relationship between alcohol consumption and glycoconjugate metabolism is complex and multidimensional. This review summarizes the advances in basic and clinical research on the molecular and cellular events involved in the metabolic effects of alcohol on glycoconjugates (glycoproteins, glycolipids, and proteoglycans). We summarize the action of ethanol, acetaldehyde, reactive oxygen species (ROS), nonoxidative metabolite of alcohol--fatty acid ethyl esters (FAEEs), and the ethanol-water competition mechanism, on glycoconjugate biosynthesis, modification, transport and secretion, as well as on elimination and catabolism processes. As the majority of changes in the cellular metabolism of glycoconjugates are generally ascribed to alterations in synthesis, transport, glycosylation and secretion, the degradation and elimination processes, of which the former occurs also in extracellular matrix, seem to be underappreciated. The pathomechanisms are additionally complicated by the fact that the effect of alcohol intoxication on the glycoconjugate metabolism depends not only on the duration of ethanol exposure, but also demonstrates dose- and regional-sensitivity. Further research is needed to bridge the gap in transdisciplinary research and enhance our understanding of alcohol- and glycoconjugate-related diseases. 相似文献
88.
Bobrovnikova-Marjon E Pytel D Riese MJ Vaites LP Singh N Koretzky GA Witze ES Diehl JA 《Molecular and cellular biology》2012,32(12):2268-2278
The endoplasmic reticulum (ER) resident PKR-like kinase (PERK) is necessary for Akt activation in response to ER stress. We demonstrate that PERK harbors intrinsic lipid kinase, favoring diacylglycerol (DAG) as a substrate and generating phosphatidic acid (PA). This activity of PERK correlates with activation of mTOR and phosphorylation of Akt on Ser473. PERK lipid kinase activity is regulated in a phosphatidylinositol 3-kinase (PI3K) p85α-dependent manner. Moreover, PERK activity is essential during adipocyte differentiation. Because PA and Akt regulate many cellular functions, including cellular survival, proliferation, migratory responses, and metabolic adaptation, our findings suggest that PERK has a more extensive role in insulin signaling, insulin resistance, obesity, and tumorigenesis than previously thought. 相似文献
89.
In this article, we categorize presently available experimental and theoretical knowledge of various physicochemical and biochemical features of amino acids, as collected in the AAindex database of known 544 amino acid (AA) indices. Previously reported 402 indices were categorized into six groups using hierarchical clustering technique and 142 were left unclustered. However, due to the increasing diversity of the database these indices are overlapping, therefore crisp clustering method may not provide optimal results. Moreover, in various large-scale bioinformatics analyses of whole proteomes, the proper selection of amino acid indices representing their biological significance is crucial for efficient and error-prone encoding of the short functional sequence motifs. In most cases, researchers perform exhaustive manual selection of the most informative indices. These two facts motivated us to analyse the widely used AA indices. The main goal of this article is twofold. First, we present a novel method of partitioning the bioinformatics data using consensus fuzzy clustering, where the recently proposed fuzzy clustering techniques are exploited. Second, we prepare three high quality subsets of all available indices. Superiority of the consensus fuzzy clustering method is demonstrated quantitatively, visually and statistically by comparing it with the previously proposed hierarchical clustered results. The processed AAindex1 database, supplementary material and the software are available at http://sysbio.icm.edu.pl/aaindex/ . 相似文献
90.
Recent studies indicated that there is a direct link between central carbon metabolism (CCM) and initiation and elongation of DNA replication in Eschericha coli. Namely, effects of certain mutations in genes coding for replication proteins (dnaA, dnaB, dnaE, dnaG, and dnaN) could be specifically suppressed by deletions of some genes, whose products are involved in CCM reactions (pta, ackA, pgi, tktB, and gpmA). Here, we demonstrate that the link between CCM and DNA synthesis can be extended to the DNA replication fidelity, as we report changes of the mutator phenotypes of E. coli dnaQ49 and dnaX36 mutants (either suppression or enhancement) by dysfunctions of zwf, pta, ackA, acnB, and icdA genes. Overexpression of appropriate wild-type CCM genes in double mutants resulted in reversions to the initial mutator phenotypes, indicating that the effects were specific. Moreover, the observed suppression and enhancement effects were not caused by changes in bacterial growth rates. These results suggest that there is a genetic correlation between CCM and DNA replication fidelity in E. coli, apart from the already documented link between CCM and DNA replication initiation control and elongation efficiency. 相似文献