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1.
The complete nucleotide sequences of two different subtypes (adr and adw) of hepatitis B virus (HBV) DNA cloned in E. coli were determined. The sequence of the viral genome of the adr clone was 3188 nucleotides long, and that of the adw clone was 3200 nucleotides long. The adr and adw clones differed from the reported cloned ayw HBV DNA (3182 nucleotides long) in 11.2% and 10.0% of nucleotides, respectively. Heterogeneity of the HBV genome in the clones with the same subtype was observed.  相似文献
2.
In rat brain three members of the protein kinase C family encoded by cDNAs termed delta, epsilon, and zeta were newly identified by molecular cloning and sequence analysis. The new members have a common structure that is closely related to but clearly distinct from the four members of the family previously isolated having alpha-, beta I-, beta II-, and gamma-sequences, although the zeta-cDNA available at present does not appear to contain a complete reading frame for protein kinase C. The delta-, epsilon-, and zeta-cDNAs all encode a characteristic cysteine-rich sequence and protein kinase domain sequence, both of which are highly homologous among the protein kinase C family. However, the new members lack one of the conserved regions that is present in alpha-, beta I-, beta II-, and gamma-sequences. An additional cDNA clone termed epsilon' was isolated, which is identical with epsilon-cDNA except for a short sequence at the 5'-terminal end region. The two members having delta- and epsilon-sequences were expressed in COS 7 cells, and partially purified and characterized. The enzymes having delta- and epsilon-sequences depend on phospholipid and diacylglycerol for the enzymatic activity, but their properties slightly differ from the previously known members of protein kinase C. Northern blot analysis suggests that the new members of protein kinase C exist in the brain and some other tissues.  相似文献
3.
We bred a microbial community capable of degrading rice straw with high efficiency. The microbial community degraded more than 60% of rice straw within 4 days at 50 °C. The high stability of the community's degradation ability was demonstrated by its tolerance of being subcultured several times in medium with/without cellulosic material, being heated to 95 °C, and freezing at –80 °C. The community degraded both nonsterilized and sterilized substrate; and its degradation ability was not affected by pH changes in the medium (initial pH 5–9). PCR-denaturing gradient gel electrophoresis (DGGE) analyses based on 16S rDNA fragments showed that the community structure remained constant after multiple subcultures extending over 2 years. DNA sequence analyses of DGGE bands indicated the coexistence of both aerobic and anaerobic bacteria in the community. Electronic Publication  相似文献
4.
Cdc25A is a novel phosphatase functioning early in the cell cycle.   总被引:30,自引:3,他引:27       下载免费PDF全文
The cdc25+ tyrosine phosphatase is a key mitotic inducer of the fission yeast Schizosaccharomyces pombe, controlling the timing of the initiation of mitosis. Mammals contain at least three cdc25+ homologues called cdc25A, cdc25B and cdc25C. In this study we investigate the biological function of cdc25A. Although very potent in rescuing the S.pombe cdc25 mutant, cdc25A is less structurally related to the S.pombe enzyme. Northern and Western blotting detection reveals that unlike cdc25B, cdc25C and cdc2, cdc25A is predominantly expressed in late G1. Moreover, immunodepletion of cdc25A in rat cells by microinjection of a specific antibody effectively blocks their cell cycle progression from G1 into the S phase, as determined by laser scanning single cell cytometry. These results indicate that cdc25A is not a mitotic regulator but a novel phosphatase that plays a crucial role in the start of the cell cycle. In view of its strong ability to activate cdc2 kinase and its specific expression in late G1, cdc2-related kinases functioning early in the cell cycle may be targets for this phosphatase.  相似文献
5.
Synthesis and processing of radiolabelled rat insulin I and II were studied by pulse-labelling freshly isolated rat islets with [3H]leucine and chasing in 2 mM glucose for up to 270 min (which minimized insulin secretion, less than 1%/h). Islet samples were taken during the chase period and analyzed for their rat insulin I and II content by high-performance liquid chromatography. Prior to 60 min chase rat insulin I accounted for greater than 85% of the radiolabelled insulin present. With longer periods of chase, the relative percentage of rat insulin II progressively increased so that by completion of proinsulin to insulin processing the two labelled rat insulins were present in the same proportion as the relative immunoreactive content, approx. 60:40% insulin I/insulin II. Thus, although islets synthesize the two insulins in proportion to their relative immunoreactive content, rat insulin I and II are processed with different kinetics.  相似文献
6.
Cloning of rat brain protein kinase C complementary DNA   总被引:12,自引:0,他引:12  
Four peptides derived from rat brain protein kinase C were partially sequenced. Using synthetic oligonucleotides deduced from the amino acid sequences as probes, a clone of complementary DNA (cDNA) was isolated from a cDNA library prepared from the same tissue. The nucleotide sequence of this cDNA clone revealed the primary structure of the carboxyl-terminal region as having 224 amino acids, with significant sequence homology with cyclic AMP-dependent and cyclic GMP-dependent protein kinases.  相似文献
7.
Elucidation of the complete sequences of four cDNA clones (alpha, beta I, beta II, and gamma) of the rat brain protein kinase C family has revealed their common structure composed of a single polypeptide chain with four constant (C1-C4) and five variable (V1-V5) regions. Although these sequences are highly homologous and closely related to one another V3-, V4-, and V5-regions of gamma-subspecies are slightly bigger than the corresponding regions of the other three subspecies. The first constant region, C1, contains a tandem repeat of cysteine-rich sequence (6, total 12 cysteine residues). The third constant region, C3, has an ATP-binding sequence which is found in many protein kinases. In adult rat whole brain, the relative activities of alpha-, beta I-, beta II-, and gamma-subspecies are roughly 16, 8, 55, and 21%, respectively. gamma-Subspecies is expressed after birth apparently only in the central nervous tissue, implying its role in the regulation of specific neuronal functions.  相似文献
8.
A sensitive enzyme immunoassay for human basic fibroblast growth factor   总被引:10,自引:0,他引:10  
A sensitive sandwich enzyme immunoassay for human basic fibroblast growth factor (HbFGF) was developed employing three monoclonal antibodies (MAb3H3, MAb98 and MAb52). The Fab' fragment of MAb3H3 which inhibits HbFGF biological activity was conjugated to horseradish peroxidase. A mixture of MAb52 and MAb98 was used in the solid phase. Neither human acidic fibroblast growth factor, hst-1/KS3 product nor acid denatured HbFGF was cross-reactive in this assay system. The detection limit of this assay system was 1 pg/well. Using this assay, some tumor cell lines were revealed to produce a higher level of bFGF than a normal one. Serum samples from normal volunteers were also assayed, and immuno-reactive HbFGF could be detected in 16 out of 57 samples at range 30 approximately 206 pg/ml.  相似文献
9.
Autosomal dominant dentatorubral-pallidoluysian atrophy (DRPLA) and Machado-Joseph disease (MJD) are neurodegenerative disorders caused by CAG trinucleotide repeat expansions. An inverse correlation of age at onset with the length of the expanded CAG trinucleotide repeats has been demonstrated, and the intergenerational instability of the length of the CAG trinucleotide repeats, which is more prominent in paternal than in maternal transmissions, has been shown to underlie the basic mechanisms of anticipation in DRPLA and MJD. Our previous observations on DRPLA and MJD pedigrees, as well as a review of the literature, have suggested that the numbers of affected offspring exceed those of unaffected offspring, which is difficult to explain by the Mendelian principle of random segregation of alleles. In the present study, we analyzed the segregation patterns in 211 transmissions in 24 DRPLA pedigrees and 80 transmissions in 7 MJD pedigrees, with the diagnoses confirmed by molecular testing. Significant distortions in favor of transmission of the mutant alleles were found in male meiosis, where the mutant alleles were transmitted to 62% of all offspring in DRPLA (chi2 = 7.69; P<.01) and 73% in MJD (chi2 = 6.82; P<.01). The results were consistent with meiotic drive in DRPLA and MJD. Since more prominent meiotic instability of the length of the CAG trinucleotide repeats is observed in male meiosis than in female meiosis and meiotic drive is observed only in male meiosis, these results raise the possibility that a common molecular mechanism underlies the meiotic drive and the meiotic instability in male meiosis.  相似文献
10.
Lysophosphatidic acid (LPA) and sphingosine 1-phosphate (Sph-1-P) are known as structurally related bio-active lipids activating platelets through their respective receptors. Although the receptors for LPA and Sph-1-P have been recently identified in various cells, the identification and characterization of ones in platelets have been reported only preliminarily. In this report, we first investigated the distinct modes of LPA and Sph-1-P actions in platelet activation and found that LPA functioned as a much stronger agonist than Sph-1-P, and high concentrations of Sph-1-P specifically desensitized LPA-induced intracellular Ca(2+) mobilization. In order to identify the responsible receptors underlying these observations, we analyzed the LPA and Sph-1-P receptors which might be expressed in human platelets, by RT-PCR. We found for the first time that Edg2, 4, 6 and 7 mRNA are expressed in human platelets.  相似文献
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