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181.
Fission yeast Sop2p: a novel and evolutionarily conserved protein that interacts with Arp3p and modulates profilin function. 总被引:9,自引:2,他引:7 下载免费PDF全文
Profilins bind to monomeric actin and also interact with ligands such as phosphoinositide 4,5-bisphosphate, the proline-rich protein VASP and a complex of four to six polypeptides identified in Acanthamoeba that includes two actin-related proteins. Here, we report the identification and characterization of an essential gene from Schizosaccharomyces pombe, sop2+, a mutation in which rescues the temperature-sensitive lethality of a profilin mutation, cdc3-124. The sop2-1 mutant is defective for cell elongation and septation, suggesting that it is involved in multiple cortical actin-requiring processes. Consistent with a role in actin cytoskeletal function, negative interactions have been identified between sop2-1 and act1-48, a mutant allele of actin. Sop2p is a novel 377 amino acid polypeptide with similarity to proteins of the beta-transducin repeat family. Sop2p-related proteins have been identified by sequencing projects in diverse species, and we have isolated a human cDNA highly related to sop2+, SOP2 Hs, which functionally complements the sop2-1 mutation. Sop2p proteins from all species contain peptide sequences identical or highly similar to two peptide sequences from an Acanthamoeba beta-transducin repeat protein present in the profilin binding complex. Biochemical analyses demonstrate that Sop2p is present in a complex which also contains the actin-related protein, Arp3p. Immunofluorescence studies reveal the presence of Sop2p in (i) punctate structures distributed throughout the cell, (ii) cables that extend the length of the cell, and (iii) a medial band in a small percentage of septating cells. Collectively these data demonstrate the interaction of Sop2p with Arp3p, profilin and actin. 相似文献
182.
The Schizosaccharomyces pombe actin-related protein, Arp3, is a component of the cortical actin cytoskeleton and interacts with profilin. 总被引:2,自引:1,他引:1 下载免费PDF全文
D McCollum A Feoktistova M Morphew M Balasubramanian K L Gould 《The EMBO journal》1996,15(23):6438-6446
The gene encoding the actin-related protein Arp3 was first identified in the fission yeast Schizosaccharomyces pombe and is a member of an evolutionarily conserved family of actin-related proteins. Here we present several key findings that define an essential role for Arp3p in the functioning of the cortical actin cytoskeleton. First, mutants in arp3 interact specifically with profilin and actin mutants. Second, Arp3 localizes to cortical actin patches which are required for polarized cell growth. Third, the arp3 gene is required for the reorganization of the actin cytoskeleton during the cell cycle. Finally, the Arp3 protein is present in a large protein complex. We believe that this complex may mediate the cortical functions of profilin at actin patches in S. pombe. 相似文献
183.
What makes a protein a protein? Hydrophobic core designs that specify stability and structural properties. 总被引:10,自引:8,他引:2 下载免费PDF全文
M. Munson S. Balasubramanian K. G. Fleming A. D. Nagi R. O'Brien J. M. Sturtevant L. Regan 《Protein science : a publication of the Protein Society》1996,5(8):1584-1593
Here we describe how the systematic redesign of a protein's hydrophobic core alters its structure and stability. We have repacked the hydrophobic core of the four-helix-bundle protein, Rop, with altered packing patterns and various side chain shapes and sizes. Several designs reproduce the structure and native-like properties of the wild-type, while increasing the thermal stability. Other designs, either with similar sizes but different shapes, or with decreased sizes of the packing residues, destabilize the protein. Finally, overpacking the core with the larger side chains causes a loss of native-like structure. These results allow us to further define the roles of tight residue packing and the burial of hydrophobic surface area in the construction of native-like proteins. 相似文献
184.
185.
A simple and rapid method for the purification of arylsulfatase A (EC 3.1.6.1) from sheep brain has been developed. This includes the concanavalin A-Sepharose affinity chromatography and the pH-dependent polymerization and depolymerization of the enzyme. By these methods a homogeneous enzyme was obtained and the enzyme was purified 7180-fold. Sheep brain arylsulfatase A has been shown to be a glycoprotein containing 25% neutral sugar and 0.5% sialic acid. The constituent neutral sugars were identified as glucose and mannose. 相似文献
186.
The identity of a peptidase activity with human serum pseudocholinesterase (PsChE) purified to apparent homogeneity was demonstrated by co-elution of both peptidase and PsChE activities from procainamide-Sepharose and concanavalin-A--Sepharose affinity chromatographic columns; comigration on polyacrylamide gel electrophoresis; co-elution on Sephadex G-200 gel filtration and coprecipitation at different dilutions of an antibody raised against purified PsChE. The purified enzyme showed a single protein band on gel electrophoresis under non-denaturing conditions. SDS gel electrophoresis under reducing conditions, followed by silver staining, also gave a single protein band (Mr approximately equal to 90,000). Peptidase activity using different peptides showed the release of C-terminal amino acids. Blocking the carboxy terminal by an amide or ester group did not prevent the hydrolysis of peptides. There was no evidence for release of N-terminal amino acids. Potent anionic or esterase site inhibitors of PsChE, such as eserine sulphate, neostigmine, procainamide, ethopropazine, imipramine, diisopropylfluorophosphate, tetra-isopropylpyrophosphoramide and phenyl boronic acid, did not inhibit the peptidase activity. An anionic site inhibitor (neostigmine or eserine) in combination with an esterase site inhibitor (diisopropylfluorophosphate) also did not inhibit the peptidase. However, the choline esters (acetylcholine, butyrylcholine, propionylcholine, benzoylcholine and succinylcholine) markedly inhibited the peptidase activity in parallel to PsChE. Choline alone or in combination with acetate, butyrate, propionate, benzoate or succinate did not significantly inhibit the peptidase activity. It appeared that inhibitor compounds which bind to both the anionic and esteratic sites simultaneously (like the substrate analogues choline esters) could inhibit the peptidase activity possibly through conformational changes affecting a peptidase domain. 相似文献
187.
Nutrition of axenically cultured A. Rutgersi was investigated by deletion and addition of various levels of essential amino acids. Reproduction was lacking when isoleucine, leucine, methionine, phenylalanine, threonine, histidine, tryptophan, and lysine were individually deleted from M-10. Normal reproduction was observed over a range of concentrations but declined to nothing at still higher concentrations of tryptophan and histidine. On the basis of these tests and analyses of both the nematode and host tissue, M-12 was devised and tested. The amino acid group of M-12 contained 7 fewer amino acids and concentrations of another 15 amino acids were adjusted; but no significant differences in reproduction occurred. 相似文献
188.
The conformation of the cyclic nonaPePtide from linseed, cyclolinoPePtide A in methanol and in acetonitrile has been elucidated
by one-and two-dimensional nuclear magnetic resonance. The molecule is folded in a β-turn conformation. CyclolinoPePtide A
interacts and weakly comPlexes with Tb3+ (a Ca2+ mimic ion) with the metal ion Positioned Proximally to the Phe residue, but with no substantial structural alteration uPon
metal binding. CyclolinoPePtide A is also seen to aid the translocation of Pr3+ (another Ca2+ mimic) across unilamellar liPosomes. However, cyclolinoPePtide A does not Phase transfer or act as an ionoPhore of calcium
ion myself. ExPeriments using lanthanide ions thus do not necessarily indicate any ionoPhoretic ability of the comPlexone
towards calcium ions. 相似文献
189.
Y Sharma C M Rao S C Rao A G Krishna T Somasundaram D Balasubramanian 《The Journal of biological chemistry》1989,264(35):20923-20927
The interaction of the cationic carbocyanine dye Stains-all (1-ethyl-2-[3-(1-ethyl-naphthol[1,2-d]thiazolin-2-ylidene)-2- methylpropenyl]naphthol[1,2-d]thiazolium bromide) with the eye lens proteins crystallins has been studied. alpha- and gamma-crystallins do not bind the dye, while beta- and delta-crystallins do, consistent with the fact that the latter two proteins bind the calcium ion. beta-Crystallin resembles parvalbumin in that it induces only the J-band of the bound dye. delta-crystallin, on the other hand, induces only the gamma-band. Analysis of the metachromasia induced in the dye by these and other proteins suggests that Stains-all is responsive to the conformational status of the region to which it binds in a protein. The J-band of the dye is activated when it binds to a globular domain, and the gamma-band is activated when it binds to a helical stretch of the protein. 相似文献
190.
Purified human serum butyrylcholine esterase (approximately 90-kDa subunit), which also exhibits aryl acylamidase activity, was subjected to limited alpha-chymotrypsin digestion. Three major protein fragments of approximately 50 kDa, approximately 21 kDa and approximately 20 kDa were found to be produced, as observed by SDS-gel electrophoresis of the chymotryptic digest. The purified butyrylcholine esterase could fully bind to a Ricinus-communis-agglutinin-Sepharose column but after chymotryptic digestion about 15-20% of the enzyme activity remained unbound and was recovered in the run-through fractions. Sephadex G-75 chromatography of the chymotryptic digest showed an enzymatically active fragment eluted at an approximate molecular mass of 20 kDa, apart from the undigested butyrylcholine esterase eluted at the void volume. The butyrylcholine esterase fragment that did not bind to Ricinus communis agglutinin also was eluted at an approximate molecular mass of 20 kDa from a Sephadex G-75 column. This enzymatically active low-molecular-mass fragment from Sephadex G-75 chromatography showed a single protein band of approximately 20 kDa on SDS-gel electrophoresis. Neutral sugar analysis of the approximately 20 kDa fragment showed the presence of mannose only, whereas the undigested butyrylcholine esterase showed the presence of both mannose and galactose. Amino-terminal-sequence analysis of the approximately 20 kDa fragment showed the sequence Arg-Val-Gly-Ala-Leu, which agrees with amino acid residues 147-151 reported for human serum butyrylcholine esterase [Lockridge et al. (1987) J. Biol. Chem. 262, 549-557]. Both cholinesterase and aryl acylamidase activities were co-eluted in all chromatographic procedures. The results suggested that limited alpha-chymotrypsin digestion of human serum butyrylcholine esterase resulted in the formation of a approximately 20-kDa enzymatically active fragment with Arg147 as its N-terminal residue and which was devoid of galactose. 相似文献