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The origin of experimental brain tumours: A sequential study 总被引:4,自引:0,他引:4
A sequential study of rat brains treated transplacentally with the neurotropic carcinogen ethylnitrosourea reveals small foci of cell proliferations from the age of 8 weeks. These lesions consist mainly of undifferentiated cells of the subependymal plate type. They occur in those areas in which gliomas develop and represent the earliest, histologically detectable, changes in the development of brain tumours. 相似文献
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In some cases the traditional essay examination question is being superseded by more objective tests, requiring straightforward answers. If administered carefully these can provide a reliable means of assessment, but much research remains to be done. 相似文献
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Frazer KA Eskin E Kang HM Bogue MA Hinds DA Beilharz EJ Gupta RV Montgomery J Morenzoni MM Nilsen GB Pethiyagoda CL Stuve LL Johnson FM Daly MJ Wade CM Cox DR 《Nature》2007,448(7157):1050-1053
A dense map of genetic variation in the laboratory mouse genome will provide insights into the evolutionary history of the species and lead to an improved understanding of the relationship between inter-strain genotypic and phenotypic differences. Here we resequence the genomes of four wild-derived and eleven classical strains. We identify 8.27 million high-quality single nucleotide polymorphisms (SNPs) densely distributed across the genome, and determine the locations of the high (divergent subspecies ancestry) and low (common subspecies ancestry) SNP-rate intervals for every pairwise combination of classical strains. Using these data, we generate a genome-wide haplotype map containing 40,898 segments, each with an average of three distinct ancestral haplotypes. For the haplotypes in the classical strains that are unequivocally assigned ancestry, the genetic contributions of the Mus musculus subspecies--M. m. domesticus, M. m. musculus, M. m. castaneus and the hybrid M. m. molossinus--are 68%, 6%, 3% and 10%, respectively; the remaining 13% of haplotypes are of unknown ancestral origin. The considerable regional redundancy of the SNP data will facilitate imputation of the majority of these genotypes in less-densely typed classical inbred strains to provide a complete view of variation in additional strains. 相似文献
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This article presents the results of a survey to determine the degree of familiarity and usage, accuracy obtained, and evaluation of different forecasting techniques. It was found that regression analysis, subjective techniques, exponential smoothing, and moving average were well known and used for specific situations. Accuracy was relatively high for aggregate short range forecasts, but decreased for longer range and product level forecasts. 相似文献
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D. S. Nelson S. Kossaŕd Prudence E. Cox 《Cellular and molecular life sciences : CMLS》1967,23(6):490-491
Résumé Des souris immunisés avec des globules rouges de mouton dans l'adjuvant de Freund produisent deux types de facteurs cytophiles pour macrophages. L'un s'attache aux macrophages trypsinisées et se trouve parmi les immunoglobulines. L'autre ne s'attache pas aux macrophages trypsinisées et se rencontre dans une fraction de sérum contenant de l'albumine et de la globuline-1.
Supported by grants from the Australian Research Grants Committee, the National Health and Medical Research Council of Australia and the Postgraduate Medical Foundation, University of Sydney. 相似文献
Supported by grants from the Australian Research Grants Committee, the National Health and Medical Research Council of Australia and the Postgraduate Medical Foundation, University of Sydney. 相似文献
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DNA restriction fragments associated with alpha 1-antitrypsin indicate a single origin for deficiency allele PI Z 总被引:3,自引:0,他引:3
The alpha 1-protease inhibitor, or alpha-antitrypsin (AAT), a major plasma inhibitor of leukocyte elastase and bacterial proteases, is encoded at the PI locus on chromosome 14 (14q24.3-q32.1). A deficiency of AAT in individuals homozygous for the PI Z allele occurs in about 1 in 2,000-8,000 caucasians and is associated with an increased risk of early adult onset emphysema and liver disease in childhood. We have now used DNA polymorphisms associated with the AAT gene to investigate the origin of the PI Z allele. Using two genomic probes extending into the 5' and 3' flanking regions, respectively, we have identified eight polymorphic restriction sites. Extensive linkage disequilibrium occurs throughout the probed region with the PI Z allele, but not with normal PI M alleles. The Z allele occurs mainly with one haplotype, indicating a single, relatively recent, origin in caucasians. 相似文献
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