全文获取类型
收费全文 | 578篇 |
免费 | 34篇 |
国内免费 | 1篇 |
专业分类
613篇 |
出版年
2023年 | 3篇 |
2022年 | 4篇 |
2021年 | 6篇 |
2020年 | 3篇 |
2019年 | 11篇 |
2018年 | 12篇 |
2017年 | 8篇 |
2016年 | 11篇 |
2015年 | 19篇 |
2014年 | 24篇 |
2013年 | 30篇 |
2012年 | 32篇 |
2011年 | 39篇 |
2010年 | 32篇 |
2009年 | 21篇 |
2008年 | 19篇 |
2007年 | 44篇 |
2006年 | 43篇 |
2005年 | 35篇 |
2004年 | 46篇 |
2003年 | 22篇 |
2002年 | 23篇 |
2001年 | 7篇 |
2000年 | 3篇 |
1999年 | 4篇 |
1998年 | 6篇 |
1997年 | 7篇 |
1996年 | 7篇 |
1995年 | 3篇 |
1994年 | 7篇 |
1993年 | 5篇 |
1992年 | 7篇 |
1991年 | 3篇 |
1990年 | 2篇 |
1989年 | 3篇 |
1988年 | 3篇 |
1987年 | 3篇 |
1986年 | 3篇 |
1985年 | 3篇 |
1984年 | 6篇 |
1983年 | 4篇 |
1982年 | 6篇 |
1981年 | 6篇 |
1980年 | 6篇 |
1978年 | 4篇 |
1977年 | 2篇 |
1976年 | 2篇 |
1975年 | 2篇 |
1974年 | 3篇 |
1962年 | 2篇 |
排序方式: 共有613条查询结果,搜索用时 0 毫秒
531.
Reynolds WF Sermet-Gaudelus I Gausson V Feuillet MN Bonnefont JP Lenoir G Descamps-Latscha B Witko-Sarsat V 《Mediators of inflammation》2006,2006(2):36735
The severity of cystic fibrosis (CF) pulmonary disease is not directly related to CFTR genotype but depends upon several parameters, including neutrophil-dominated inflammation. Identification of agents modulating inflammation constitutes a relevant goal. Myeloperoxidase (MPO) is involved in both microbicidal and proinflammatory neutrophil activities. The aim of this study was to evaluate whether the -463GA MPO promoter polymorphism is linked to clinical severity of CF-associated pulmonary inflammation. This polymorphism significantly affects the level of MPO gene expression in leukocytes and the G allele is more expressing than the A allele. We show that MPO genotype significantly influences the severity of pulmonary disease in early stages, prior to the development of chronic lung infections, with GG genotype being associated with more severe CF disease. Our findings indicate that the level of MPO gene expression influences the CF pathogenesis, presumably reflecting cellular damage by MPO-generated oxidants or other activity of MPO in airway inflammation. 相似文献
532.
BACKGROUND: Two families of proteins that transport small peptides, the oligopeptide transporters (OPTs) and the peptide transporters (PTRs), have been recognized in eukaryotes. Higher plants contain a far greater number of genes for these transporters than do other eukaryotes. This may be indicative of the relative importance of (oligo)peptides and their transport to plant growth and metabolism. RECENT PROGRESS: Recent studies are now allowing us to assign functions to these transporters and are starting to identify their in-planta substrates, revealing unexpected and important contributions of the transporters to plant growth and developmental processes. This Botanical Briefing appraises recent findings that PTRs and OPTs have key roles to play in the control of plant cell growth and development. Evidence is presented that some of these transporters have functions outside that of nitrogen nutrition and that these carriers can also surprise us with their totally unexpected choice of substrates. 相似文献
533.
Miguel Bento Perry Gustafson Wanda Viegas Manuela Silva 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2010,121(3):489-497
Genetic and epigenetic modifications resulting from different genomes adjusting to a common nuclear environment have been
observed in polyploids. Sequence restructuring within genomes involving retrotransposon/microsatellite-rich regions has been
reported in triticale. The present study uses inter-retrotransposon amplified polymorphisms (IRAP) and retrotransposon microsatellite
amplified polymorphisms (REMAP) to assess genome rearrangements in wheat–rye addition lines obtained by the controlled backcrossing
of octoploid triticale to hexaploid wheat followed by self-fertilization. The comparative analysis of IRAP and REMAP banding
profiles, involving a complete set of wheat–rye addition lines, and their parental species revealed in those lines the presence
of wheat-origin bands absent in triticale, and the absence of rye-origin and triticale-specific bands. The presence in triticale × wheat
backcrosses (BC) of rye-origin bands that were absent in the addition lines demonstrated that genomic rearrangement events
were not a direct consequence of backcrossing, but resulted from further genome structural rearrangements in the BC plant
progeny. PCR experiments using primers designed from different rye-origin sequences showed that the absence of a rye-origin
band in wheat–rye addition lines results from sequence elimination rather than restrict changes on primer annealing sites,
as noted in triticale. The level of genome restructuring events evaluated in all seven wheat–rye addition lines, compared
to triticale, indicated that the unbalanced genome merger situation observed in the addition lines induced a new round of
genome rearrangement, suggesting that the lesser the amount of rye chromatin introgressed into wheat the larger the outcome
of genome reshuffling. 相似文献
534.
Carolina Bernardes Wanda Maria Risso Günther 《Human ecology: an interdisciplinary journal》2014,42(4):617-623
The Brazilian rural population is estimated to be around 30 million people and many rural areas do not have universal access to basic infrastructure services, including those related to solid waste. There are very few scientific studies on rural domestic solid waste and more investigative work is needed to provide information for appropriate solid waste management policies. This paper aims to characterize rural domestic solid waste in terms of quantity and quality. Amazonian rural communities were chosen for our case study. The issue of domestic solid waste was characterized both by means of interviews, at household level, and by a study of industrialized products traded in the communities located along the banks of the Juruá River, in the Brazilian Amazon. Quantitative results have shown that generation of solid waste in these rural communities reaches 0.5 kg/person/day. Organic matter represents 90 % of domestic solid waste generation and is mainly reused to feed animals and/or is composted using a method called paú. Inorganic solid waste (10 %) is either reused, burned or inadequately dumped in open sites. Based on these data, the annual production of solid waste is 437 tons per year in these communities. Since infrastructure services are virtually non-existent in this rural context, even this amount of solid waste may have a serious environmental impact, with negative effects on the population’s health, particularly in terms of hazardous waste. Even though solid waste management solutions for rural populations might not always be based on economic efficiency, decision makers responsible for development and planning should present solutions that are socially, technologically, environmentally and economically suitable for this context. 相似文献
535.
Dominik M Kłopocka W Pomorski P Kocik E Redowicz MJ 《Cell motility and the cytoskeleton》2005,61(3):172-188
Amoeba proteus, the highly motile free-living unicellular organism, has been widely used as a model to study cell motility. However, molecular mechanisms underlying its unique locomotion and intracellular actin-based-only trafficking remain poorly understood. A search for myosin motors responsible for vesicular transport in these giant cells resulted in detection of 130-kDa protein interacting with several polyclonal antibodies against different tail regions of human and chicken myosin VI. This protein was binding to actin in the ATP-dependent manner, and immunoprecipitated with anti-myosin VI antibodies. In order to characterize its possible functions in vivo, its cellular distribution and colocalization with actin filaments and dynamin II during migration and pinocytosis were examined. In migrating amoebae, myosin VI immunoanalog localized to vesicular structures, particularly within the perinuclear and sub-plasma membrane areas, and colocalized with dynamin II immunoanalog and actin filaments. The colocalization was even more evident in pinocytotic cells as proteins concentrated within pinocytotic pseudopodia. Moreover, dynamin II and myosin VI immunoanalogs cosedimented with actin filaments, and were found on the same isolated vesicles. Blocking endogenous myosin VI immunoanalog with anti-myosin VI antibodies inhibited the rate of pseudopodia protrusion (about 19% decrease) and uroidal retraction (about 28% decrease) but did not affect cell morphology and the manner of cell migration. Treatment with anti-human dynamin II antibodies led to changes in directionality of amebae migration and affected the rate of only uroidal translocation (about 30% inhibition). These results indicate that myosin VI immunoanalog is expressed in protist Amoeba proteus and may be involved in vesicle translocation and cell locomotion. 相似文献
536.
Binding sites in the full-length, ligand-binding domain of rat vitamin D receptor (LBD-rVDR) for an active hormone derived from vitamin D (1alpha,25-dihydroxyvitamin D(3)) and three of its C-2 substituted analogs were compared by nuclear magnetic resonance (NMR) spectroscopy. Specific residue labeled with [UL]-(15)N(2) Trp allowed assignment of the side-chain H(epsilon1) and N(epsilon1) resonances of the single tryptophan residue at position 282 in LBD-rVDR. Comparison of (1)H[(15)N] Heteronuclear Single Quantum Correlation (HSQC) spectra of apo and holo LBD-rVDR revealed that the position of the Trp282 H(epsilon1) and N(epsilon1) signals are sensitive to the presence of the ligand in the receptor cavity. Binding of the ligands to LBD-rVDR results in a shift of both Trp H(epsilon1) and N(epsilon1) resonances to lower frequencies. The results indicate that the interaction between the ligands and Trp282 is not responsible for differences in calcemic activity observed in vitamin D analogs. 相似文献
537.
Migration of crawling cells (amoebae and some kinds of the tissue cells) is a process related to the dynamic reorganization of actomyosin cytoskeleton. That reorganization engages actin polymerization and de-polymerization, branching of actin network and interaction of myosin II with actin filaments. All those cytoskeleton changes lead to the cell progression, contraction and shifting of the uropod and the cell adhesion. Numerous external stimuli, which activate various surface receptors and signal transduction pathways, can promote migration. Rho family proteins play an important role in the regulation of actin cytoskeleton organization. The most known members of this family are Rho, Rac and Cdc42 proteins, present in all mammalian tissue cells. These proteins control three different stages of cell migration: progression of the frontal edge, adhesion which stabilizes the frontal area, and de-adhesion and shifting of the uropod. Cdc42 and Rac control cell polarization, lamellipodium formation and expansion, organization of focal complexes. Rho protein regulates contractile activity of actomyosin cytoskeleton outside the frontal area, and thus contraction and de-adhesion of the uropod. 相似文献
538.
539.
The aim of this study was to compare checkerboard method with E-test assay for interaction analysis of aminoglycosides in combination with other antibiotics on selected clinical bacterial strains. In the first step, MIC values of analysed antibiotics, against particular bacterial strain were established. In the next step, antibiotics interaction was analysed by checkerboard technique and E-test. We found some difficulties while comparing these two methods. The checkerboard and E-test results corresponded in about 55%. Twenty-one percentage of results obtained by both methods showed some discrepancies. In 15% of cases, because of high MICs values, comparison of the results was impossible. Some investigators declare FIC indexes, from over 0.5 up to 4, for neutral effects. Sharing this point of view, above 21% of discrepancies results agreed. In such situation, definite disagreement was observed only in 8% of obtained results. In this investigation, additive and neutral effects were dominant. The E-test technique is less-laborous than standard agar method. In this study the E-test assay indicated synergy in only one case. Because of the manner in which the E-test strips were placed on the agar (scales intersecting at the MICs) only dramatic cases of antagonism were detected. Mild cases were undetected because the inhibition zone run under the crossed strips and was therefore unreadable and interpreted as indifference. On the basis of these results, examination of interactions between antibiotics by E-test, appears to be possible alternative to checkerboard method with mentioned limitations. 相似文献
540.
Blizzard TA DiNinno F Chen HY Kim S Wu JY Chan W Birzin ET Yang YT Pai LY Hayes EC DaSilva CA Rohrer SP Schaeffer JM Hammond ML 《Bioorganic & medicinal chemistry letters》2005,15(17):3912-3916
An optimized side chain for dihydrobenzoxathiin SERAMs was discovered and attached to four dihydrobenzoxathiin platforms. The novel SERAMs show exceptional estrogen antagonist activity in uterine tissue and an MCF-7 breast cancer cell assay. 相似文献