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51.
S. C. Choy B. S. Weir 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1977,49(2):63-77
Summary For a population undergoing recurrent selection, a method is presented for determining the average inbreeding coefficients at the end of each breeding cycle. The coefficients are derived in terms of probability measures that genes are identical by descent. For the one-locus case, two digametic measures are defined and employed in the derivation of a recurrence formula for the inbreeding coefficient. Two further classes of measures, trigametic and quadrigametic, are required for transition from one cycle to the previous one to allow the calculation of the inbreeding function for the two-locus case. Numerical values of the average probability of double identity by descent for populations with various imposed assumptions are listed to illustrate the effects of linkage and population size on the accrual of inbreeding and hence of homozygosity.Paper number 5018 of the Journal Series of the North Carolina Agricultural Experiment Station, Raleigh, North Carolina. This investigation was supported in part by NIH research grant number GM 11546 from the National Institute of General Medical Sciences. 相似文献
52.
B. S. Weir 《Genetics》1992,130(4):873-887
An analysis is presented of data collected by the Federal Bureau of Investigation at six unlinked variable number of tandem repeats (VNTR) loci for the United States population. Databases have been constructed of VNTR profiles of Caucasians, Blacks and Hispanics from Florida, Texas and California. There was very little evidence for correlations between lengths for pairs of VNTR fragments, within or between loci. When the fragment lengths were amalgamated into discrete bins, there was also little evidence for disequilibrium over all genotypes, within or between loci, for the Caucasian database, although some disequilibrium was found for the Black and Hispanic databases. No disequilibrium was found for the Caucasian or Black databases when tests were confined to heterozygous individuals. In cases of global disequilibrium, local tests can be applied to specific genotypes. The results suggest that, at the bin level, frequencies of VNTR profiles can generally be estimated as the products of the frequencies of the constituent elements. This overcomes the problem of estimating population frequencies when any particular profile does not exist in the database. There is some evidence for different frequencies, at the individual bin level, between geographic samples within each of the Caucasian, Black and Hispanic databases, and considerable evidence for differences between the three databases. These differences are less evident for the frequencies of four-locus profiles. 相似文献
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Cytochrome P-448 (mol wt 55,000 Daltons) from rabbit liver was purified to a specific content of 16.6 nmol/mg. Mice were immunised with this preparation, their spleens removed and dissociated lymphocytes hybridised with myeloma cells. Four monoclonal antibodies against cytochrome P-448 were raised and partially characterised. All four antibodies interacted with cytochrome P-448 in intact microsomal fractions and selectively immunoadsorbed cytochrome P-448 from solubilised microsomal preparations. One of the antibodies inhibited benzo[a] pyrene hydroxylase activity in a reconstituted system, one had no effect on activity and two increased activity. The possible applications of such antibodies are discussed. 相似文献
55.
Regulation of glyoxysomal enzymes during germination of cucumber. Temporal changes in translatable mRNAs for isocitrate lyase and malate synthase 总被引:10,自引:0,他引:10
E M Weir H Riezman J M Grienenberger W M Becker C J Leaver 《European journal of biochemistry》1980,112(3):469-477
The relative levels of translatable messenger RNA for isocitrate lyase and malate synthase were determined in the dry seed and for the first seven days of development of cucumber cotyledons. After extraction and quantification of total and poly(A)-rich RNA each day, the RNA fractions were translated in an optimized wheat germ system and the specific polypeptides were immunoprecipitated quantitatively. The radiolabeled isocitrate lyase and malate synthase polypeptides were then fractionated on dodecylsulphate/polyacrylamide gels, visualized by exposure to X-ray film and quantified densitometrically. The relative levels of translatable messenger RNA for these enzymes rise and fall with a developmental program similar to the enzyme activities, but preceding the latter by about one day. This implies that the rise in enzyme activity is dependent upon a prior postgerminative increase in translatable messenger RNA for the enzymes. These studies also suggest that messenger RNA levels may be regulated, at least in part, by light. 相似文献
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For loci with multiple alleles, hypotheses about linkage disequilibrium may be tested on the complete set of gametic data, or on various collapsed sets of data. Collapsing data into a few alleles at each locus can change the power of the tests, as implied in a recent paper by Zouros, Golding and Mackay (1977). We show that the nature of such changes can be found from properties of the noncentral chi-square distribution, and that the magnitude and direction of these changes depend on the levels of linkage disequilibria, allelic frequencies and degrees of freedom. 相似文献
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The extent of divergence between partially isolated sub-populations for electrophoretically detectable alleles was formulated assuming the island model of migration and the charge state model of mutation. At equilibrium the ratio of the variance of charge between the means of k different islands to the average within-island variance of charge was shown to be approximately 4Nemk2/(k-1)2 where Ne is the effective size of each island population and m is the migration rate. This ratio was calculated from published data for eight polymorphic loci in six island populations of Drosophila willistoni. Under the assumption that all variants are selectively neutral, migration rates of greater than 10 adults per generation per island are required to explain the observed similarity of the allelic profiles in D. willistoni. Since the islands studied appear to be virtually completely isolated it was concluded either that the observed protein variants are adaptive and maintained in populations by some form of balancing selection or that the observed variants themselves are neutral but natural selection acts to restrict the appearance of more extreme variants in the charge carried. 相似文献