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21.
Kanji Hori Yoshiharu Shimada Chihiro Oiwa Keisuke Miyazawa Keiji Ito 《Journal of applied phycology》1993,5(2):219-223
Nine species of marine algae have been assessed for the presence of novel hemagglutinins not extractable with buffer, unless
the algal tissue was pretreated with Pronase. All species examined contained hemagglutinins, indicating the existence of a
novel group of hemagglutinins which differed from those reported previously in marine algae. 相似文献
22.
23.
The constituents of the steam volatile oils from two kinds of Allium fistulosum, A. fistulosum var. caespitosum and A. chinense, have been investigated by GC and spectral techniques (IR, UV, GC/MS, 1H NMR and 13C NMR). The compounds identified from the neutral fraction of each volatile oil included sulphides, thiolanes, alcohols, aldehydes, ketones, furanones and others. Among the sulphur compounds, dipropyl disulphide comprised ca 28% of A. fistulosum oil, ca 23% of A. fistulosum var. caespitosum oil and ca 30% of A. chinense oil. A. fistulosum oil was characterized by a large quantity of tridecan-2-one (ca 52%) and 2,3-dihydro-2-octyl-5-methylfuran-3-one (ca 16%). Also, a large amount of 2,3-dihydro-2-hexyl-5-methylfuran-3-one (ca 20%) was isolated from A. chinense oil. 相似文献
24.
The folding–unfolding process of reduced bovine pancreatic trypsin inhibitor was investigated with an idealized model employing approximate free energies. The protein is regarded to consist of only Cα and Cβ atoms. The backbone dihedral angles are the only conformational variables and are permitted to take discrete values at every 10°. Intraresidue energies consist of two terms: an empirical part taken from the observed frequency distributions of (?,ψ) and an additional favorable energy assigned to the native conformation of each residue. Interresidue interactions are simplified by assuming that there is an attractive energy operative only between residue pairs in close contact in the native structure. A total of 230,000 molecular conformations, with no atomic overlaps, ranging from the native state to the denatured state, are randomly generated by changing the sampling bias. Each conformation is classified according to its conformational energy, F; a conformational entropy, S(F) is estimated for each value of F from the number of samples. The dependence of S(F) on energy reveals that the folding–unfolding transition for this idealized model is an “all-or-none” type; this is attributable to the specific long-range interactions. Interresidue contact probabilities, averaged over samples representing various stages of folding, serve to characterize folding intermediates. Most probable equilibrium pathways for the folding–unfolding transition are constructed by connecting conformationally similar intermediates. The specific details obtained for bovine pancreatic trypsin inhibitor are as follows: (1) Folding begins with the appearance of nativelike medium-range contacts at a β-turn and at the α-helix. (2) These grow to include the native pair of interacting β-strands. This state includes intact regular secondary conformations, as well as the interstrand sheet contacts, and corresponds to an activated state with the highest free energy on the pathway. (3) Additional native long-range contacts are completely formed either toward the amino terminus or toward the carboxyl terminus. (4) In a final step, the missing contacts appear. Although these folding pathways for this model are not consistent with experimental reports, it does indicate multiple folding pathways. The method is general and can be applied to any set of calculated conformational energies and furthermore permits investigation of gross folding features. 相似文献
25.
O Nureki K Suzuki M Hara-Yokoyama T Kohno H Matsuzawa T Ohta T Shimizu K Morikawa T Miyazawa S Yokoyama 《European journal of biochemistry》1992,204(2):465-472
The gene for the Glu-tRNA synthetase from an extreme thermophile, Thermus thermophilus HB8, was isolated using a synthetic oligonucleotide probe coding for the N-terminal amino acid sequence of Glu-tRNA synthetase. Nucleotide-sequence analysis revealed an open reading frame coding for a protein composed of 468 amino acid residues (Mr 53,901). Codon usage in the T. thermophilus Glu-tRNA synthetase gene was in fact similar to the characteristic usages in the genes for proteins from bacteria of genus Thermus: the G + C content in the third position of the codons was as high as 94%. In contrast, the amino acid sequence of T. thermophilus Glu-tRNA synthetase showed high similarity with bacterial Glu-tRNA synthetases (35-45% identity); the sequences of the binding sites for ATP and for the 3' terminus of tRNA(Glu) are highly conserved. The Glu-tRNA synthetase gene was efficiently expressed in Escherichia coli under the control of the tac promoter. The recombinant T. thermophilus Glu-tRNA synthetase was extremely thermostable and was purified to homogeneity by heat treatment and three-step column chromatography. Single crystals of T. thermophilus Glu-tRNA synthetase were obtained from poly(ethylene glycol) 6000 solution by a vapor-diffusion technique. The crystals diffract X-rays beyond 0.35 nm. The crystal belongs to the orthorhombic space group P2(1)2(1)2(1), with unit-cell parameters of a = 8.64 nm, b = 8.86 nm and c = 8.49 nm. 相似文献
26.
Some common properties of lectins from marine algae 总被引:10,自引:1,他引:9
Twelve kinds of lectins isolated from four species of marine algae, Boodlea coacta (Chlorophyta) and Hypnea japonica, Carpopeltis flabellata and Solieria robusta (Rhodophyta), were compared for their chemical and biological properties. These lectins were proteins or glycoproteins, similar to terrestrial plant lectins. However, unlike most terrestrial plant lectins, they had a small molecular size (4,200 to 25,000 daltons), were mostly monomeric, and had no affinity for monosaccharides. They strongly agglutinated trypsin-treated rabbit erythrocytes, and their activities commonly were inhibited by glycoproteins bearing N-glycans. From hemagglutination-inhibition tests with various glycoproteins and related compounds, it was found that B. coacta lectins recognize high-mannose N-glycans; H. japonica lectins complex N-glycans, and C. flabellata and S. robusta lectins recognize both types of N-glycans. 相似文献
27.
T Eki T Enomoto A Miyajima H Miyazawa Y Murakami F Hanaoka M Yamada M Ui 《The Journal of biological chemistry》1990,265(1):26-33
A large number of mutants that are temperature sensitive (ts) for growth have been isolated from mouse mammary carcinoma FM3A cells by an improved selection method consisting of cell synchronization and short exposures to restrictive temperature. The improved method increased the efficiency of isolating DNA ts mutants, which showed a rapid decrease in DNA-synthesizing ability after temperature shift-up. Sixteen mutants isolated by this and other methods were selected for this study. Flow microfluorometric analysis of these mutants cultured at a nonpermissive temperature (39 degrees C) for 16 h indicated that five clones were arrested in the G1 to S phase of the cell cycle, six clones were in the S to G2 phase, and two clones were arrested in the G2 phase. The remaining three clones exhibited 8C DNA content after incubation at 39 degrees C for 28 h, indicating defects in mitosis or cytokinesis. These mutants were classified into 11 complementation groups. All the mutants except for those arrested in the G2 phase and those exhibiting defects in mitosis or cytokinesis showed a rapid decrease in DNA synthesis after temperature shift-up without a decrease in RNA and protein synthesis. The polyomavirus DNA cell-free replication system, which consists of polyomavirus large tumor antigen and mouse cell extracts, was used for further characterization of these DNA ts mutants. Among these ts mutants, only the tsFT20 strain, which contains heat-labile DNA polymerase alpha, was unable to support the polyomavirus DNA replication. Analysis by DNA fiber autoradiography revealed that DNA chain elongation rates of these DNA ts mutants were not changed and that the initiation of DNA replication at the origin of replicons was impaired in the mutant cells. 相似文献
28.
Retinal Gangliosides in RCS Mutant Rats 总被引:8,自引:7,他引:1
Thomas N. Seyfried Robert K. Yu Nobuko Miyazawa Yin-Lok Lai 《Journal of neurochemistry》1982,39(1):277-279
Abstract: The distribution of retinal gangliosides was studied in normal and mutant rats with retinal dystrophy at 30 and 180 days of age. The loss of photoreceptor cells in the retinal dystrophic RCS rats was not associated with a significant reduction in the relative distribution of any of the major retinal gangliosides. The loss of photoreceptors, however, caused a marked increase in total retinal ganglioside concentration. These findings suggest that photoreceptor cells contain a low concentration of gangliosides and that no major retinal ganglioside is localized or concentrated in these cells. The cellular localization and function of the most abundant retinal ganglioside, GD3 , is discussed. 相似文献
29.
Differential Cellular Enrichment of Gangliosides in the Mouse Cerebellum: Analysis Using Neurological Mutants 总被引:15,自引:12,他引:3
Abstract: The cellular distribution of gangliosides in the cerebellum was studied in a series of adult mouse mutants that lose specific populations of neurons. The weaver ( wv ) mutation destroys the vast majority of granule cells, whereas the Purkinje cell degeneration mutation ( pcd ) destroys the vast majority of Purkinje cells. The staggerer ( sg ) and lurcher ( Lc ) mutations, on the other hand, destroy the vast majority of both granule and Purkinje cells. A proliferation of reactive glial cells, which occurs as a consequence of neuronal loss, has been reported in the sg/sg and pcd/pcd mutants, but not in the wv/wv mutant. Compared with the normal (+/+) mice, the concentration (μg/100 mg dry weight) of GD1a was significantly reduced in those mutants that lost granule cells, but was not reduced in the pcd/pcd mutant. The concentration of GTIa , on the other hand, was significantly reduced in those mutants that lost Purkinje cells, but was not reduced in the wv/wv mutant. A significant elevation in the concentration of GD3 , which may be related to the proliferation of reactive glial cells, was observed in the pcd/pcd, sglsg , and Lc /+ mutants, but was not observed in the wv/wv mutant. Because these ganglioside abnormalities were confined to the cerebellum, they cannot result from genetic defects in ganglioside metabolism. Instead, these abnormalities result from a differential enrichment of gangliosides in neural membranes. Our findings suggest that GDT1a is more heavily concentrated in granule cells than Purkinje cells, whereas the opposite appears true for GTla . It also appears that GD3 is enriched in reactive glial cells and may play an important role during the morphological transformation of neural membranes. 相似文献
30.
Induction of a novel long-chain acyl-CoA hydrolase in rat liver by administration of peroxisome proliferators 总被引:4,自引:0,他引:4
The activity of long-chain acyl-CoA hydrolase in rat liver was increased by the administration of peroxisome proliferators, such as ethyl p-chlorophenoxyisobutyrate, di(2-ethylhexyl)phthalate or acetylsalicylic acid. The induced activity was mainly confined in the soluble fluid after the subcellular fractionation. The enzyme was purified nearly to homogeneity from livers of rats treated with di(2-ethylhexyl)phthalate. The specific activity of the final preparation was 247 mumol palmitoyl-CoA hydrolyzed min-1 mg protein-1. The molecular weight of the native enzyme was estimated to be 150 000 by gel filtration and that of the subunits was 41 000 by sodium dodecyl sulfate/polyacrylamide gel electrophoresis. The activity of the enzyme was not increased but inhibited by bovine serum albumin or Triton X-100. The molecular and catalytic properties of the enzyme suggest that the induced enzyme was different from mitochondrial and microsomal long-chain acyl-CoA hydrolyses in liver. 相似文献