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161.
A fasciocutaneous flap for vaginal and perineal reconstruction 总被引:3,自引:0,他引:3
A skin and fascia flap from the medial thigh is proposed for vaginal and perineal reconstruction. Dissection, vascular injection, and radiographs of 20 fresh cadaver limbs uniformly demonstrated the presence of a communicating suprafascial vascular plexus in the medial thigh. Three to four nonaxial vessels were consistently found to enter the proximal plexus from within 5 cm of the perineum. Preservation of these vessels permitted reliable elevation of a 9 X 20 cm fasciocutaneous flap without using the gracilis muscle as a vascular carrier. Fifteen flaps in 13 patients were used for vaginal replacement and coverage of vulvectomy, groin, and ischial defects. Depending on the magnitude of the defect, simultaneous and independent elevation of the gracilis muscle provided additional vascularized coverage as needed. Our experience indicates that the medial thigh fasciocutaneous flap is a durable, less bulky, and potentially sensate alternative to the gracilis musculocutaneous flap for vaginal and perineal reconstruction. 相似文献
162.
Mammotrophs or prolactin (PRL) cells were identified in the adenohypophysis of adult golden hamsters by immunocytochemical techniques with a polyclonal anti-PRL, that was proved to be specific to PRL by the dot immunoblotting test. Postembedding immunostaining was performed on Araldite thin sections by immunoperoxidase and immunogold methods. PRL cells were classified into three types according to the different size of the secretory granules. The Type A cells were usually small and angular or oval in shape, and had secretory granules ranging in diameter from 100-230 nm, and showed poorly developed organelles. The Type B and C cells were larger and round or ovoid in shape, contained larger granules, 230-280 nm and 280-570 nm, respectively, and displayed well developed organelles. Immunoreactive PRL cells in the male pituitaries were far less numerous than in the nonpregnant female glands, and were mostly of the Type A and B, whereas in the female the Type C and B cells predominated. In pregnant females, Type C cells became activated and increased in number, while the other two types decreased in proportion. In lactating females, Type A and B cells significantly increased in number at the expense of the Type C cells; meanwhile, the exocytosis of secretory granules was frequently found in all types of PRL cells. The present findings suggest that Type C and B PRL cells, especially the former, are potent in producing and releasing PRL and highly responsive to various physiological stimuli, while Type A cells are probably relatively inert in synthetic activity. 相似文献
163.
164.
165.
Cloning and expression in Escherichia coli of chromosomal mercury resistance genes from a Bacillus sp. 总被引:6,自引:3,他引:3 下载免费PDF全文
A 7.9-kilobase (kb) chromosomal fragment was cloned from a mercury-resistant Bacillus sp. In Escherichia coli, in the presence of a second plasmid carrying functional transport genes, resistance to HgCl2 and to phenylmercury acetate (PMA) was expressed. Shortening the cloned fragment to 3.8 kb abolished resistance to PMA but not to HgCl2. In Bacillus subtilis, the 3.8-kb fragment produced mercuric reductase constitutively but did not produce resistance to HgCl2 or to PMA. 相似文献
166.
Influence of GATC sequences on Escherichia coli DNA mismatch repair in vitro. 总被引:6,自引:4,他引:2 下载免费PDF全文
A L Lu 《Journal of bacteriology》1987,169(3):1254-1259
The effect of the number and position of DNA adenine methylation (dam) sites, i.e., d(GATC) sequences, on mismatch repair in Escherichia coli was investigated. The efficiency of repair was measured in an in vitro assay which used an f1 heteroduplex containing a G/T mismatch within the single EcoRI site. Both an increase in the number of dam sites and a shortened distance between dam site and mismatched site increased the efficiency of mismatch repair. The sequences adjacent to d(GATC) also affected the efficiency of methylation-directed mismatch repair. Furthermore, heteroduplexes with one extra dam site located close to either the 5' or 3' end of the excised base increased the repair efficiency to about the same extent. The findings suggest that the mismatch repair pathway has no preferred polarity. 相似文献
167.
Characterization of the Erwinia carotovora pelB gene and its product pectate lyase. 总被引:8,自引:3,他引:5 下载免费PDF全文
The pelB gene encodes pectate lyase B, one of three pectate lyases identified in Erwinia carotovora EC. Pectate lyase B was purified from Escherichia coli containing the pelB gene on a recombinant plasmid. The activity of the protein was optimal at a pH of 8.3. The amino acid composition, N-terminal amino acid sequence, and C-terminal peptide sequence were determined and compared with the polypeptide sequence deduced from the DNA sequence of pelB. Purified pectate lyase B started at amino acid 23 of the predicted sequence, suggesting that a 22-amino-acid leader peptide had been removed. Pectate lyase B of E. carotovora EC and pectate lyase B of E. chrysanthemi EC16 contain 352 and 353 amino acids, respectively (N. T. Keen, S. Tanaki, W. Belser, D. Dahlbeck, and B. Staskawicz, J. Bacteriol. 168:595-606, 1986). The two proteins are 72% homologous on the basis of DNA sequence data, and 75% of the amino acids are identical. 相似文献
168.
Ornithine decarboxylase of the African trypanosome Trypanosoma brucei brucei had an estimated native molecular weight of 100,000 by gel filtration and a subunit molecular weight of 45,000 by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The gene encoding this enzyme, present in a single copy in T. brucei, was identified by mouse ornithine decarboxylase cDNA under relatively stringent conditions of hybridization and subcloned in a 5.9-kilobase (kb) SstI fragment from a cosmid clone into the plasmid pUC 19. This clone encompassed a 2.8-kb SstII fragment that contained the entire T. brucei ornithine decarboxylase gene. The 2.8-kb SstII fragment hybridized to a 2.4-kb mRNA that presumably encodes the parasite enzyme. The 2.8-kb SstII fragment was partially sequenced and found to contain an open reading frame of 445 amino acids that has 61.5% homology with the corresponding sequence of the mouse enzyme. The only major discrepancies between the two enzymes are the addition of a 20-amino acid N-terminal peptide and the deletion of a 36-amino acid C-terminal peptide and the T. brucei ornithine decarboxylase. The C terminus has been postulated to be one of the structural factors associated with rapid in vivo turnover of mammalian ornithine decarboxylase. The absence of this C-terminal peptide in T. brucei ornithine decarboxylase predicts a slow turnover for the parasite enzyme in vivo, and this is supported by our experimental data. The lack of turnover of ornithine decarboxylase in trypanosomes may constitute the basis of selective antitrypanosomal action of the irreversible enzyme inhibitor DL-alpha-difluoromethylornithine. 相似文献
169.
A method has been developed for exploring the quaternary fine structure of oligomeric proteins by crosslinking studies and applied to bovine heart mitochondrial F1-ATPase. The F1 was first labeled with 1-fluoro-2,4-dinitro-[14C]benzene, subsequently reduced with sodium hydrosulfite, and finally cross-linked with 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide. Gel electrophoresis in the chemically modified protein in the presence of sodium dodecyl sulfate and mercaptoethanol showed the existence of a 105-115-kilodalton molecular species in addition to the five monomeric subunits of F1. This cross-linked species could be alpha 2, alpha beta, or beta 2. Isolation of the cross-linked species and titration with 5,5'-dithiobis-(2-nitrobenzoic acid) showed the absence of sulfhydryl group. Therefore, the cross-linked species must be the dimer beta 2. After digestion of the purified beta 2 with pepsin, a single radioactive peptide was isolated. Determination of the amino acid sequence of this peptide and comparison of its radioactivity with the total radioactivity on beta-subunits show that it was formed exclusively by cross-linking Lys162 of one beta-subunit with Glu199 of another beta-subunit. The observation that two beta-subunits can be cross-linked by a rigid phenylenediamine bridge of 5.7- or 4.3-A length is difficult to reconcile with the widely assumed structure of F1 with the alpha- and beta-subunits occupying alternate corners of a planar hexagon, but is consistent with the structure in which a triangular set of three beta-subunits sits above a triangular set of three alpha-subunits in a staggered conformation. 相似文献
170.
pH-dependent structural transition in rabbit skeletal troponin C 总被引:1,自引:0,他引:1
Although the crystal structure of troponin C is known (Herzberg, O., and James, M. N. G. (1985) Nature 313, 653-659; Sundaralingam, M., Bergstrom, R., Strasburg, G., Rao, S. T., Roychowdhury, P., Greaser, M., and Wang, B. C. (1985) Science 227, 945-948), its structure in solution, particularly under physiological conditions, has not been established. We examined the conformation of troponin C under a variety of conditions by measuring the distance between sites located in the N- and C-terminal domains using the technique of resonance energy transfer. The donor was the luminescent lanthanide ion Tb3+ bound at the low affinity metal sites in the N-terminal domain. The acceptor was 4-dimethylaminophenylazophenyl-4'-maleimide attached at Cys-98 in the C-terminal domain. The distance between these sites was found to be greater than 5.2 nm at pH 5.0, 2.7 nm at pH 6.8 for uncomplexed troponin C, and 4.1 nm for troponin C complexed with troponin I at pH 6.8. These findings suggest that uncomplexed troponin C undergoes a pH-dependent transition from an elongated conformation, compatible with the crystal structure at acidic pH, to a more compact conformation at neutral pH. When complexed with troponin I, troponin C adopts a conformation of intermediate length compared to the uncomplexed molecule at pH 6.8 and 5.0. 相似文献