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排序方式: 共有915条查询结果,搜索用时 31 毫秒
101.
Marc Lamblin Basel Dabbas Russell Spingarn Rodrigo Mendoza-Sanchez Tian-Tian Wang Beum-Soo An Dao Chao Huang Richard Kremer John H. White James L. Gleason 《Bioorganic & medicinal chemistry》2010,18(11):4119-4137
Incorporation of zinc-binding groups into the side-chain of 1α,25-dihydroxyvitamin D3 (1,25D) fully bifunctional hybrid molecules which act both as vitamin D receptor agonists and histone deacetylase inhibitors. These bifunctional hybrids display in vitro antiproliferative activity against the AT84 squamous carcinoma cell line while lacking the in vivo hypercalcemic effects of 1,25D. 相似文献
102.
103.
Veiga N Torres J Domínguez S Mederos A Irvine RF Díaz A Kremer C 《Journal of inorganic biochemistry》2006,100(11):1800-1810
104.
105.
106.
Molle V Brown AK Besra GS Cozzone AJ Kremer L 《The Journal of biological chemistry》2006,281(40):30094-30103
Phosphorylation of proteins by Ser/Thr protein kinases (STPKs) has recently become of major physiological importance because of its possible involvement in virulence of bacterial pathogens. Although Mycobacterium tuberculosis has eleven STPKs, the nature and function of the substrates of these enzymes remain largely unknown. In this work, we have identified for the first time STPK substrates in M. tuberculosis forming part of the type II fatty acid synthase (FAS-II) system involved in mycolic acid biosynthesis: the malonyl-CoA::AcpM transacylase mtFabD, and the beta-ketoacyl AcpM synthases KasA and KasB. All three enzymes were phosphorylated in vitro by different kinases, suggesting a complex network of interactions between STPKs and these substrates. In addition, both KasA and KasB were efficiently phosphorylated in M. bovis BCG each at different sites and could be dephosphorylated by the M. tuberculosis Ser/Thr phosphatase PstP. Enzymatic studies revealed that, whereas phosphorylation decreases the activity of KasA in the elongation process of long chain fatty acids synthesis, this modification enhances that of KasB. Such a differential effect of phosphorylation may represent an unusual mechanism of FAS-II system regulation, allowing pathogenic mycobacteria to produce full-length mycolates, which are required for adaptation and intracellular survival in macrophages. 相似文献
107.
With regard to adaptation of green ash (Fraxinus pennsylvanica
Marshall) to ecological conditions in Croatia, pollen germination and pollen tube length after 2, 4 and 6 hours were examined in vitro at 10, 15, 20 and 25°C during two years 2001 and 2002. Narrow leaved ash (F. angustifolia
Vahl) pollen served as a control in 2002. The year, time and temperature, and the interaction between time and temperature were
significant for both germination percentage and pollen tube length. Interactions year × temperature and year × time were significant
for pollen tube length only. The highest germination percentage (17.86% in 2001 and 19.40% in 2002) of green ash pollen was
at 15°C after 6 hours. The pollen tube length was greatest at 20°C (393.46 μm) in 2001 and 25°C (899.50 μm) in 2002 after
6 hours. Narrow leaved ash pollen had the highest germination percentage (19.22%) at 20°C after 6 hours and was significantly
reduced at 25°C. The pollen tube length was greatest at 25°C (518.90 μm) after 6 hours. It can be concluded that green ash
pollen has satisfactory germination in ecological conditions in Croatia and that the optimum temperature for pollen germination
is higher than 20°C. 相似文献
108.
Photorespiration and β-carboxylation in brown macroalgae 总被引:1,自引:0,他引:1
Bruno P. Kremer 《Planta》1980,150(2):189-190
Photorespiration has been assayed in a variety of marine macroalgae by the Warburg oxygen inhibitory effect and the percentage14C-labeling of glycine and serine. It was found that particularly the members of the brown macroalgae examined, such asFucus andLaminaria (Phaeophyceae), show a rather weak response to high O2 partial pressure. This observation is attributed to the appreciably high potential for -carboxylation via PEP-carboxykinase, generally occurring in brown seaweeds. 相似文献
109.
Rombouts Y Brust B Ojha AK Maes E Coddeville B Elass-Rochard E Kremer L Guerardel Y 《The Journal of biological chemistry》2012,287(14):11060-11069
The "cell wall core" consisting of a mycolyl-arabinogalactan-peptidoglycan (mAGP) complex represents the hallmark of the mycobacterial cell envelope. It has been the focus of intense research at both structural and biosynthetic levels during the past few decades. Because it is essential, mAGP is also regarded as a target for several antitubercular drugs. Herein, we demonstrate that exposure of Mycobacterium bovis Bacille Calmette-Guérin or Mycobacterium marinum to thiacetazone, a second line antitubercular drug, is associated with a severe decrease in the level of a major apolar glycolipid. This inhibition requires MmaA4, a methyltransferase reported to participate in the activation process of thiacetazone. Following purification, this glycolipid was subjected to detailed structural analyses, combining gas-liquid chromatography, mass spectrometry, and nuclear magnetic resonance. This allowed to identify it as a 5-O-mycolyl-β-Araf-(1→2)-5-O-mycolyl-α-Araf-(1→1)-Gro, designated dimycolyl diarabinoglycerol (DMAG). The presence of DMAG was subsequently confirmed in other slow growing pathogenic species, including Mycobacterium tuberculosis. DMAG production was stimulated in the presence of exogenous glycerol. Interestingly, DMAG appears structurally identical to the terminal portion of the mycolylated arabinosyl motif of mAGP, and the metabolic relationship between these two components was provided using antitubercular drugs such as ethambutol or isoniazid known to inhibit the biosynthesis of arabinogalactan or mycolic acid, respectively. Finally, DMAG was identified in the cell wall of M. tuberculosis. This opens the possibility of a potent biological function for DMAG that may be important to mycobacterial pathogenesis. 相似文献
110.
Most adaptive traits are controlled by large number of genes that may all together be the targets of selection. Adaptation may thus involve multiple but not necessarily substantial allele frequency changes. This has important consequences for the detection of selected loci and implies that a quantitative genetics framework may be more appropriate than the classical 'selective sweep' paradigm. Preferred methods to detect loci involved in local adaptation are based on the detection of 'outlier' values of the allelic differentiation F(ST) . A quantitative genetics framework is adopted here to review theoretical expectations for how allelic differentiation at quantitative trait loci (F(STQ) ) relates to (i), neutral genetic differentiation (F(ST) ) and (ii), phenotypic differentiation (Q(ST) ). We identify cases where results of outlier-based methods are likely to be poor and where differentiation at selected loci conveys little information regarding local adaptation. A first case is when neutral differentiation is high, so that local adaptation does not necessitate increased differentiation. A second case is when local adaptation is reached via an increased covariance of allelic effects rather than via allele frequency changes, which is more likely under high gene flow when the number of loci is high and selection is recent. The comparison of theoretical predictions with observed data from the literature suggests that polygenic local adaptation involving only faint allele frequency changes are very likely in some species such as forest trees and for climate-related traits. Recent methodological improvements that may alleviate the weakness of F(ST) -based detection methods are presented. 相似文献