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41.
Penetration of Eimeria tenella sporozoites under different oxygen concentrations in vitro. 总被引:1,自引:0,他引:1
Sporozoites of Eimeria tenella (Wisconsin strain) were inoculated onto monolayers of normal chicken kidney fibroblasts and cultured in RPMI-1640 supplemented with 5% fetal bovine serum, sodium bicarbonate, and gentamicin under either aerobic, 5% CO2/95% air, or anaerobic conditions. Penetration of fibroblasts by sporozoites under CO2 or anaerobic conditions at 2 and 24 hr postinoculation was 3-4 times greater than that in the aerobic atmosphere. Effect of reduced oxygen concentrations, i.e., 20.0, 12.5, and 5.0% oxygen, was also investigated in an N2-O2-CO2 incubator. Under 5.0 and 12.5% oxygen at 2 and 24 hr postinoculation, the number of sporozoites that penetrated was about 4 and 2 times greater, respectively, than under 20.0% O2. These results indicate that lower oxygen concentrations provide for greater penetration by E. tenella sporozoites in cultured cells. 相似文献
42.
S J Prestrelski T Arakawa C S Wu K D O'Neal K R Westcott L O Narhi 《The Journal of biological chemistry》1992,267(1):319-322
Circular dichroism (CD) and Fourier transform infrared spectroscopic studies have shown that the secondary structure of transforming growth factor alpha (TGF-alpha) is very similar to that of epidermal growth factor (EGF). The infrared spectra revealed a minor difference between the two proteins, in particular in the beta-sheet structure. A large difference was observed with CD between the two proteins in the apparent conformation each adopts when the disulfide bonds are reduced. Reduced TGF-alpha showed a distinct alpha-helical conformation only at a high trifluoroethanol concentration, whereas reduced EGF assumed an alpha-helical conformation in the absence of trifluoroethanol. This indicates that these two proteins adopt different secondary structures in the absence of disulfide bonds, although they assume similar folding structures in their presence. These data suggest that the disulfide bonds to a large degree dictate the conformation of these two proteins. Additionally, differences in the dynamic behavior between EGF and TGF-alpha were also observed. Infrared experiments showed that the hydrogen-deuterium exchange rate is much higher for TGF-alpha than for EGF, indicating that TGF-alpha is a more flexible molecule. The rate of reduction of the disulfide bonds by dithiothreitol was also faster for TGF-alpha. Therefore, it can be concluded that although EGF and TGF-alpha have a similar overall conformation, TGF-alpha is a more flexible molecule than EGF. 相似文献
43.
Arakawa Keita; Mizuno Katsuhiko; Kishitani Sachie; Takabe Tetsuko 《Plant & cell physiology》1992,33(7):833-840
The changes in the level of the protein for betaine aldehydedehydrogenase, which catalyzes the last step in the synthesisof glycinebetaine, were analyzed with antiserum raised againstSDS-denatured betaine aldehyde dehydrogenase from spinach. Inbarley leaves, the levels of betaine aldehyde dehydrogenaseprotein were found to be enhanced by the addition of 200 mMNaCl to the growth medium. These changes in the level of theenzyme protein corresponded to those in the activity of theenzyme, as described in our previous study (Arakawa et al. 1990).The extent of this enhancement was reduced when barley plantswere relieved from salt stress. An increase in the level ofthe protein was also induced by water stress, such as the withholdingof water or the addition of polyethylene glycol 6000. Betainealdehyde dehydrogenase protein was detected in etiolated leavesand roots, as well as in green leaves. In etiolated leaves,the level of betaine aldehyde dehydrogenase protein was notaffected by salt stress.
1 This work was supported by a grant from the Bio-Media Projectof the Japanese Ministry of Agriculture, Forestry and Fisheries(BMP92-III-l-1). 相似文献
44.
S J Prestrelski T Arakawa W C Kenney D M Byler 《Archives of biochemistry and biophysics》1991,285(1):111-115
The secondary structures of two recombinant human growth factors, platelet-derived growth factor and the basic fibroblast growth factor, have been quantitatively examined by using Fourier transform infrared spectroscopy. These studies, carried out in D2O, focus on the conformation-sensitive amide I region. Resolution enhancement techniques, including Fourier self-deconvolution and derivative spectroscopy, were combined with band fitting techniques to quantitate the spectral information from the broad, overlapped amide I band. The results presented here indicate that both proteins are rich in beta-structures. The remainder of the platelet-derived growth factor exists largely as irregular or disordered conformations with a moderate amount of alpha-helix and a small portion of reverse turns. By contrast, the basic fibroblast growth factor is much richer in reverse turn structures and contains a lesser portion of irregularly folded or disordered structures. Based on circular dichroism studies which indicate no alpha-helix in bFGF, components near 1655 cm-1 in the bFGF spectra are tentatively assigned to loops. The results of this study emphasize the need for using a combination of circular dichroism and infrared studies for spectroscopic characterization of protein secondary structure. 相似文献
45.
The reaction products of methyl thioglycolate with dynemicin A, dynemicin H and dynemicin S, were isolated by HPLC purification and identified spectroscopically. The major product, dynemicin H (C30H23NO9), was determined to be a C-8 hydrogen analogue of dynemicins L and N in which the enediyne core is aromatized. The minor product, dynemicin S (C33H27No11S), is an adduct of methyl thioglycolate at the C-8 position. By using NADPH instead of methyl thioglycolate, the reaction with dynemicin A also gives the same major product (dynemicin H). The nucleotide-specific cleavage of dynemicin A induced by addition of methyl thioglycolate is remarkably similar to that induced by addition of NADPH, whereas dynemicins H and S show no DNA cleavage activities. The formation of dynemicins H and S provides a rationale for the reductive and nucleophilic activations of dynemicin A. 相似文献
46.
47.
Unlike most mitochondrial matrix proteins, the mitochondrial 3-oxoacyl-CoA thiolase [EC 2.3.1.16] is synthesized with no cleavable presequence and possesses information for mitochondrial targeting and import in the mature protein. This mitochondrial thiolase is homologous with the mature portion of peroxisomal 3-oxoacyl-CoA thiolase and acetoacetyl-CoA thiolase [EC 2.3.1.9] of Zoogloea ramigera along the entire sequence. A hybrid gene encoding the NH2-terminal 16 residues (MALLRGVFIVAAKRTP) of the mitochondrial thiolase fused to the mature portion of rat ornithine carbamoyltransferase [EC 2.1.3.3] (lacking its own presequence) was transfected into COS cells, and subcellular localization of the fusion protein was analyzed. Cell fractionation and immunocytochemical analyses showed that the fusion protein was localized in the mitochondria. These results indicate that the NH2-terminal 16 residues of the mitochondrial thiolase function as a noncleavable signal for mitochondrial targeting and import of this enzyme protein. The fusion protein containing the NH2-terminal 14 residues (MSTPSIVIASARTA) of the bacterial thiolase was also localized in the mitochondria. On the other hand, the fusion protein containing the corresponding portion (MQASASDVVVVHGQRTP) of the peroxisomal thiolase appeared not to be localized to the mitochondria. These results show that the import signal of mitochondrial 3-oxoacyl-CoA thiolase originated from the NH2-terminal portion of the ancestral thiolase. The ancestral enzyme might have already possessed a mitochondrial import activity when mitochondria appeared first, or that it might have acquired the import activity during evolution by accumulation of point mutations in the NH2-terminal portion of the enzyme. 相似文献
48.
T Yoshimoto Y Yamamoto T Arakawa H Suzuki S Yamamoto C Yokoyama T Tanabe H Toh 《Biochemical and biophysical research communications》1990,172(3):1230-1235
The cDNA for a 12-lipoxygenase was isolated from cDNA library of human erythroleukemia cells. The cDNA had an open reading frame encoding 663 amino acids with a calculated molecular weight of 75,513. The deduced amino acid sequence of human 12-lipoxygenase exhibited 41.5%, 65.3% and 65.4% identity with human 5-lipoxygenase, human 15-lipoxygenase and porcine 12-lipoxygenase, respectively. Blot hybridization analysis of RNA from human erythroleukemia cells demonstrated a single species (3.1 kb) of mRNA with the cDNA probe for 12-lipoxygenase of these cells, but not with the cDNA for porcine leukocyte enzyme. The cytosol of Escherichia coli transformed with a recombinant pUC19 plasmid oxygenated the position 12 of arachidonic acid. 相似文献
49.
T Sato T Uchiumi R Kominami M Arakawa 《Biochemical and biophysical research communications》1990,172(2):496-502
New antibodies reactive with a 20 KDal ribosomal protein of the large subunit were found in sera from two of eighty patients with systemic lupus erythematosus. This antigenic protein was identified as L12 by the mobility in two-dimensional gel electrophoresis. Both sera also contained anti-P activity against three acidic phosphoproteins (P proteins), but this activity was completely inhibited by preincubation with the isolated P proteins. Therefore, these anti-L12 can be useful for studying the function of L12 in protein synthesis. 相似文献
50.
2,2,2-trichloroethyl 3,6-di-O-benzyl-2-deoxy-2-phthalimido-β-d-glucopyranoside (9) was synthesized in 6 steps from the readily available 1,3,4,6-tetra-O-acetyl-2-deoxy-2-phthalimido-β-d-glucopyranose in 25% overall yield by employing the stannyl method for the regioselective activation of hydroxyl groups. Dibenzyl ether 9 was then glycosylated with appropriate glycosyl donors to afford lactosamine and chitobiose derivatives in good yield. 相似文献