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71.
Correlation between ribosomal DNA polymorphism and electrophoretic enzyme polymorphism in Yersinia 总被引:8,自引:0,他引:8
N Picard-Pasquier B Picard S Heeralal R Krishnamoorthy P Goullet 《Journal of general microbiology》1990,136(8):1655-1666
Ribosomal DNA (rDNA) polymorphism was compared with electrophoretic enzyme polymorphism for the intra- and interspecies differentiation of Yersinia enterocolitica, Y. pseudotuberculosis, Y. intermedia, Y. aldovae, Y. frederiksenii and Y. kristensenii. DNA from 90 strains previously classified into six zymotypes (Y. enterocolitica and Y. frederiksenii) and into distinct enzyme electrophoretic patterns (the four other species) was digested with EcoRI or HindIII and analysed by Southern blotting. The six species were clearly differentiated from each other. In Y. enterocolitica, the subclassification of biotype 1 into zymotypes 1A and 1B was also reflected in the rDNA and the four other bio-zymotypes gave four different classes of restriction pattern. In Y. frederiksenii, both EcoRI and HindIII gave five distinct riboclasses which correlated with the zymotypes. In the four other species, the phenotype polymorphism appeared to be better correlated with the restriction fragment length polymorphism data in some enzymes than others. The data demonstrate that the inter- and intraspecies classification by rDNA polymorphism using two restriction enzymes is similar to that based on electrophoretic enzyme polymorphism. The analysis could be refined for taxonomic and epidemiological purposes by using other restriction enzymes. 相似文献
72.
The sodium dodecyl sulfate driven dissociation reactions of daunorubicin (1), mitoxantrone (2), ametantrone (3), and a related anthraquinone without hydroxyl groups on the ring or side chain (4) from calf thymus DNA, poly[d(G-C)]2, and poly[d(A-T)]2 have been investigated by stopped-flow kinetic methods. All four compounds exhibit biphasic dissociation reactions from their DNA complexes. Daunorubicin and mitoxantrone have similar dissociation rate constants that are lower than those for ametantrone and 4. The effect of temperature and ionic strength on both rate constants for each compound is similar. An analysis of the effects of salt on the two rate constants for daunorubicin and mitoxantrone suggests that both of these compounds bind to DNA through a mechanism that involves formation of an initial outside complex followed by intercalation. The daunorubicin dissociation results from both poly[d(G-C)]2 and poly[d(A-T)]2 can be fitted with a single exponential function, and the rate constants are quite close. The ametantrone and 4 polymer dissociation results can also be fitted with single exponential curves, but with these compounds the dissociation rate constants for the poly[d(G-C)]2 complexes are approximately 10 times lower than for the poly[d(A-T)]2 complexes. Mitoxantrone also has a much slower dissociation rate from poly[d(G-C)]2 than from poly[d(A-T)]2, but its dissociation from both polymers exhibits biphasic kinetics. Possible reasons for the biphasic behavior with the polymers, which is unique to mitoxantrone, are selective binding and dissociation from the alternating polymer intercalation sites and/or dual binding modes of the intercalator with both side chains in the same groove or with one side chain in each groove. 相似文献
73.
The literature data on the activity of histidine-15 modified hen egg white lysozyme are conflicting: the modified enzyme is
reported to have more activity, similar activity or less activity by different authors. Amino acid analysis had shown modification
of the single His-15. Detailed activity studies on His-15-modified (by iodoacetic acid or diethyl pyrocarbonate) lysozyme
have shown that the contradicting reports are due to the specific choices of ionic strengths and cell wall substrate concentrations
and can be attributed to the substrate being negatively charged. Our analysis suggests that even though histidine-15 is far
removed from the active site of lysozyme, its chemical modification or binding of the negatively-charged substrate near it,
changes the conformation around the active site. However, the change in the optimum activity on chemically modifying His-15
is small. 相似文献
74.
Guy Trabuchet Jacques Elion Olga Dunda Claudine Lapouméroulie Rolande Ducrocq Sellama Nadifi Isidore Zohoun Andre Chaventre Pierre Carnevale Ronald L. Nagel Rajagopal Krishnamoorthy Dominique Labie 《Human genetics》1991,87(5):597-601
Summary The origin of the C mutation was studied by characterizing nucleotide sequence polymorphisms on C chromosomes of patients from various African countries. In the majority of cases, the C mutation was found in linkage disequilibrium with a single chromosomal structure as defined by classical RFLP haplotypes, intergenic nucleotide sequence polymorphisms immediately upstream of the -globin gene, and intragenic -globin gene polymorphisms (frameworks). In addition, three atypical variant chromosomes carrying the C mutation were observed, and are most probably explained either by a meiotic recombination (two cases) or by one nucleotide substitution occurring in an unstable array of tandemly repeated sequences (one case). These data demonstrate the unicentric origin of the C mutation in central West Africa, with subsequent mutational modification in a small number of instances. The data also supports gene flow of the C chromosome from subsaharan Africa to North Africa. 相似文献
75.
A novel beta thalassemia gene with a single base mutation in the conserved polypyrimidine sequence at the 3' end of IVS 2 总被引:4,自引:1,他引:3 下载免费PDF全文
C Beldjord C Lapoumeroulie J Pagnier M Benabadji R Krishnamoorthy D Labie A Bank 《Nucleic acids research》1988,16(11):4927-4935
An adult Algerian patient with homozygous beta thalassemia was found to have a unique beta thalassemia gene. Cloning and sequencing revealed that the only abnormality present in this beta gene is a transversion in the polypyrimidine stretch at the 3' end of the large intervening sequence (IVS 2) six bases 5' to the consensus AG dinucleotide sequence (CCGCCCACAG instead of CCTCCCACAG). In addition, digestion of the cloned fragment by the enzyme Mnl I demonstrates the disappearance of a restriction site as expected. This is the first example of a defect in the consensus sequence at the 3' end of an IVS leading to a thalassemia phenotype presumably due to decreased splicing. 相似文献
76.
A simple mathematical model depicting blood flow in the capillary is developed with an emphasis on the permeability property
of the blood vessel based on Starling's hypothesis. In this study the effect of inertia has been neglected in comparison with
the viscosity on the basis of the smallness of the Reynolds number of the flow in the capillary. The capillary blood vessel
is approximated by a circular cylindrical tube with a permeable wall. The blood is represented by a couple stress fluid. With
such an ideal model the velocity and pressure fields are determined. It is shown that an increase in the couple stress parameter
increases the resistance to the flow and thereby decreases the volume rate flow. A comparison of the results with those of
the Newtonian case has also been made. 相似文献
77.
The nature of codon 57 in the HLA-DQ beta gene was recently reported as a potential marker of genetic susceptibility to insulin-dependent diabetes mellitus. When exploring the relevance of this marker by using genomic DNA amplification, we encountered difficulties resulting from the coamplification of the homologous DX beta region. A simple strategy is proposed to amplify the DQ beta region exclusively. It involves the preliminary digestion of genomic DNA with a restriction enzyme which cleaves DX beta specifically, leaving intact the DQ beta sequence. The amplified material is suitable for dot blot analysis and restriction enzyme digestion. This strategy is of general interest when homologous sequences impair the specificity of enzymatic DNA amplification. 相似文献
78.
Stopped-flow kinetic, 1H, and 31P NMR analysis of the intercalation of ethidium with poly d(G-C) X d(G-C) 总被引:1,自引:0,他引:1
S Chandrasekaran C R Krishnamoorthy R L Jones J C Smith W D Wilson 《Biochemical and biophysical research communications》1984,122(2):804-809
In a low salt buffer (0.011 M Na+) stopped-flow kinetic results for the SDS driven dissociation of an ethidium-Poly d(G-C) X d(G-C) complex are 8.7, 23, and 58.5 s-1 at 20, 30, and 40 degrees C, respectively. These results predict that in NMR experiments at high field strengths, ethidium should be in slow exchange among polymer binding sites. This has been found to be the case for both 31P (109 MHz) and 1H (imino proton spectra in H2O at 270 MHz) experiments. At higher salt, and/or higher temperature, and/or lower field, the bound and free peaks are no longer resolved in the NMR spectra. Good agreement is obtained between the stopped-flow kinetic results and the coalescence temperature observed in NMR experiments. Imino protons in base pairs on both sides of the intercalated ethidium are shifted approximately one ppm upfield while only the phosphate groups at the intercalation site experience large chemical shifts. 相似文献
79.
80.