全文获取类型
收费全文 | 503篇 |
免费 | 16篇 |
国内免费 | 26篇 |
出版年
2023年 | 1篇 |
2022年 | 2篇 |
2021年 | 4篇 |
2020年 | 4篇 |
2019年 | 6篇 |
2018年 | 9篇 |
2017年 | 12篇 |
2016年 | 7篇 |
2015年 | 12篇 |
2014年 | 18篇 |
2013年 | 29篇 |
2012年 | 6篇 |
2011年 | 18篇 |
2010年 | 18篇 |
2009年 | 38篇 |
2008年 | 28篇 |
2007年 | 24篇 |
2006年 | 23篇 |
2005年 | 8篇 |
2004年 | 24篇 |
2003年 | 20篇 |
2002年 | 18篇 |
2001年 | 2篇 |
2000年 | 8篇 |
1999年 | 11篇 |
1998年 | 10篇 |
1997年 | 8篇 |
1996年 | 10篇 |
1995年 | 8篇 |
1994年 | 10篇 |
1993年 | 9篇 |
1992年 | 14篇 |
1991年 | 8篇 |
1990年 | 7篇 |
1989年 | 7篇 |
1988年 | 5篇 |
1987年 | 9篇 |
1986年 | 4篇 |
1985年 | 12篇 |
1984年 | 15篇 |
1983年 | 18篇 |
1982年 | 10篇 |
1981年 | 10篇 |
1980年 | 10篇 |
1979年 | 7篇 |
1975年 | 1篇 |
1974年 | 1篇 |
1973年 | 2篇 |
排序方式: 共有545条查询结果,搜索用时 15 毫秒
21.
22.
NADPH-protochlorophyllide oxidoreductase (PChilde reductase, EC 1.3.1.33), a key enzyme in light-dependent greening and the conversion of etioplasts into chloroplasts was investigated in the the greening mutant C-2A' of the unicellular green alga Scenedesmus obliquus. In the absence of detergent, the solubilization of the enzyme increased with high glycerol concentrations in the buffer. Solubilization capacities of 4 non-ionic or zwitterionic detergents, Triton X-100, CHAPS, octylglucoside and decyl-maltopyranoside, were compared. Due to the addition of these detergents, the enzyme activity in the soluble fraction was increased severalfold. Hydrophobicity of the enzyme was analyzed by Triton X-114 phase partitioning. The protein had a preference for the aqueous phase, but its distribution was strongly influenced by the glycerol concentration of the buffer. These results indicate that the PChlide reductase of the green alga Scenedesmus obliquus is a hydrophobic, membrane-associated enzyme, but not an integral membrane protein. 相似文献
23.
Marie-Jos Navarro-Prigent Isabelle Sguin Pierre Boivin Didier Dhermy 《Biology of the cell / under the auspices of the European Cell Biology Organization》1995,83(1):33-38
Summary— The membrane skeleton, responsible for shape and mechanical properties of the red cell, was purified by the Triton extraction procedure in presence of 5 mM, 150 mM or 600 mM NaCl. The proportion of spectrin, protein 4.1 and actin present in erythrocyte skeletons does not depend on the molarity of NaCl used. In contrast ankyrin, protein band 3 and protein 4.2 are removed from skeletons as the ionic strength increased. Solubilization assays of membrane skeletons were used to study protein interactions inside the skeleton. Solubilization was performed by Tris, a non-selective disruptive reagent, or by p-mercuribenzene sulfonic acid (PMBS), which principally release spectrin and actin. Tris action was assessed by calculation of the percentage of solubilized proteins, which increased proportionally with Tris molarity. PMBS action was kinetically determined as the decrease in skeleton turbidity. With these two reagents, we observed a lower dissociation of skeletons prepared with high ionic strength buffer. Erythrocyte pretreatment with okadaic acid, an inhibitor of serine-threonine phosphatases, revealed a phosphorylation-induced skeleton gelation and a better resistance to Tris-solubilization. 相似文献
24.
Microbial mineralization of organic phosphate in soil 总被引:35,自引:0,他引:35
Summary Phosphate-dissolving microorganisms were isolated from non-rhizosphere and rhizosphere of plants. These isolates included
bacteria, fungi and actinomycetes. In broth cultures, Gram-negative short rod,Bacillus andStreptomyces species were found to be more active in solubilizing phosphate thanAspergillus, Penicillium, Proteus, Serratia, Pseudomonas andMicrococcus spp. The sterile soils mixed with isolated pure culture showed slower mineralization of organic phosphate than that of non-sterile
soil samples at all incubation periods. Maximum amount of phosphate mineralization by isolated microorganisms were obtained
at the 60th and the 75th day of incubation in sterile and non-sterile soils respectively. The mixed cultures were most effective
in mineralizing organic phosphate and individuallyBacillus sp. could be ranked next to mixed cultures. Species ofPseudomonas andMicrococcus were almost the same as that of the control under both sterile and non-sterile conditions. 相似文献
25.
Summary Inoculation effect ofA. chroococcum, P. striata andA. awamorii on yield and nutrients uptake in rice was studied under green house conditions. The organisms appreciably increased the yield and uptake of nutrients with or without chemical fertilizers. Phosphorussolubilizing microorganisms and a mixture of the three showed better response than the rest of the treatments among single and mixed culture inoculations respectively. Chemical fertilizers further improved the yield and nutrients uptake. The yield response remained unaffected by replacing superphosphate with rock phosphate and microbial inoculations. 相似文献
26.
Ilkka Helander Kirsi Saukkonen Elias Hakalehto Martti Vaara 《FEMS microbiology letters》1984,24(1):39-42
Abstract A procedure is described in which the protein crystals produced by Bacillus thuringiensis var. israelensis were solubilized in 50 mM NaOH with 10 mM EDTA at pH 11.7. This solubilization procedure gave protein gel profiles identical with those for intact crystals while maintaining full biological activity in the form of erythrocyte lysis capability. Crystals with and without protease activity were equally toxic to Aedes aegypti larvae. 相似文献
27.
Equilibrium measurements of the binding of central nervous system myelin basic protein to sodium dodecyl sulphate, sodium deoxycholate and lysophosphatidylcholine have been obtained by gel permeation chromatography and dialysis. This protein associates with large amounts of each of these surfactants: the apparent saturation weight ratios (surfactant/protein) being for dodecyl sulphate at ionic strengths 0.30 and 0.10, respectively, for deoxycholate (at 0.12 ionic strength) and for lysophosphatidylcholine. Binding to the ionic surfactants increases markedly close to their critical micelle concentrations. Sedimentation analysis shows that at 0.30 ionic strength in excess dodecyl sulphate the protein is monomeric. It becomes dimeric when the binding ratio falls below 1 at a free detergent concentration of approximately 0.25 mM: below this concentration much of the protein and detergent forms an insoluble complex. The amount of dodecyl sulphate bound at high concentrations and at both above-mentioned ionic strengths corresponds closely to that expected for interaction of a single polypeptide with two micelles. Variability of deoxycholate micelle size on interaction with other molecules precludes a similar analysis for this surfactant. Association was observed only with single micelles of lysophosphatidylcholine. The results provide strong evidence for dual lipid-binding sites on basic protein and indicate that lipid bilayer cross-linking by this protein may be effected by single molecules. 相似文献
28.
29.
Structural changes in the purified accompanying detergent inactivation were investigated by monitoring changes in light scattering, intrinsic protein fluorescence, and tryptophan to β-parinaric acid fluorescence resonance energy transfer. Two phases of inactivation were observed using the non-ionic detergents, digitonin, Lubrol WX and Triton X-100. The rapid phase involves detergent monomer insertion but little change in protein structure or little displacement of closely associated lipids as judged by intrinsic protein fluorescence and fluorescence resonance energy transfer. Lubrol WX and Triton X-100 also caused membrane fragmentation during the rapid phase. The slower phase of inactivation results in a completely inactive enzyme in a particle of 400 000 daltons with 20 mol/mol of associated phospholipid. Fluorescence changes during the course of the slow phase indicate some dissociation of protein-associated lipids and an accompanying protein conformational change. It is concluded that non-parallel inhibition of and activity by digitonin (which occurs during the rapid phase of inactivation) is unlikely to require a change in the oligomeric state of the enzyme. It is also concluded that at least 20 mol/mol of tightly associated lipid are necessary for either or activity and that the rate-limiting step in the slow inactivation phase involves dissociation of an essential lipid. 相似文献
30.
Solubilization and Partial Characterization of Angiotensin II Receptors from Rat Brain 总被引:2,自引:1,他引:1
I. R. Siemens G. N. Swanson S. J. Fluharty J. W. Harding 《Journal of neurochemistry》1991,57(2):690-700
Rat brain angiotensin II (Ang II) receptors were solubilized with a yield of 30-40% using the synthetic detergent 3[(3-cholamidopropyl)dimethylammonio)]-1-propanesulfonate. Kinetic analysis employing the high-affinity antagonist 125I-Sar1,Ile8-Ang II indicated that the solubilized receptors exhibited the same properties as receptors present within intact brain membranes. Furthermore, there was a positive correlation (r = 0.99) between the respective pIC50 values of a series of agonist and antagonists competing for 125I-Sar1,Ile8-Ang II labeled binding sites in either solubilized or intact membranes. Moreover, covalent labeling of 125I-Ang II to solubilized receptors with the homo-bifunctional cross-linker disuccinimidyl suberate, followed by gel filtration, revealed one major and one minor binding peak with apparent molecular weights of 64,000 and 115,000, respectively. Two binding proteins of comparable molecular weights (i.e., 112,000 and 60,000) were also identified by covalent cross-linking of 125I-Ang II to solubilized brain membranes followed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis. In contrast, only the smaller molecular mass binding protein was observed when solubilized membranes were labeled with the antagonist 125I-Sar1,Ile8-Ang II prior to gel filtration, and chromatofocusing of antagonist labeled sites revealed only one peak with an isoelectric point of 6.2. The successful solubilization of these binding sites should facilitate continued investigation of Ang II receptors in the brain. 相似文献