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111.
112.
Analysis of growth and division often involves measurements made on cell populations, which tend to average data. The value
of single cell analysis needs to be appreciated, and models based on findings from single cells should be taken into greater
consideration in our understanding of the way in which cell size and division are co-ordinated. Examples are given of some
single cell analyses in mammalian cells, yeast and other microorganisms. There is also a short discussion on how far the results
are in accord with simple models. 相似文献
113.
114.
Background
A new sequence independent bioinformatics approach allowing genome-wide search for proteins with similar three dimensional structures has been developed. By utilizing the numerical output of the sequence threading it establishes putative non-obvious structural similarities between proteins. When applied to the testing set of proteins with known three dimensional structures the developed approach was able to recognize structurally similar proteins with high accuracy.Results
The method has been developed to identify pathogenic proteins with low sequence identity and high structural similarity to host analogues. Such protein structure relationships would be hypothesized to arise through convergent evolution or through ancient horizontal gene transfer events, now undetectable using current sequence alignment techniques. The pathogen proteins, which could mimic or interfere with host activities, would represent candidate virulence factors.The developed approach utilizes the numerical outputs from the sequence-structure threading. It identifies the potential structural similarity between a pair of proteins by correlating the threading scores of the corresponding two primary sequences against the library of the standard folds. This approach allowed up to 64% sensitivity and 99.9% specificity in distinguishing protein pairs with high structural similarity.Conclusion
Preliminary results obtained by comparison of the genomes of Homo sapiens and several strains of Chlamydia trachomatis have demonstrated the potential usefulness of the method in the identification of bacterial proteins with known or potential roles in virulence.115.
Inference for imputation estimators 总被引:16,自引:0,他引:16
116.
Efficient estimation of the prevalence of multiple rare traits 总被引:1,自引:0,他引:1
117.
F Kierszenbaum W R Cuna L A Beltz M B Sztein 《Journal of immunology (Baltimore, Md. : 1950)》1990,144(10):4000-4004
Coculture of blood forms of Trypanosoma cruzi with human PMBC suppresses the expression of several molecules involved in lymphocyte activation, including receptors for IL-2. Our work was initially undertaken to establish whether this effect required physical parasite-PBMC contact or was mediated by a T. cruzi secretion product. Using culture inserts with cell-impermeable membranes, we were able to demonstrate significant suppression of PHA-induced lymphoproliferation whether the trypanosomes were placed in the same compartment as, or separated from, the PBMC. Similar effects were observed by using supernatants from T. cruzi suspensions. These supernatants, which we refer to as trypanosomal immunosuppressive factor, also inhibited IL-2R expression in response to PHA stimulation. The suppressive effect of the secretion product(s) of T. cruzi was reversible, as evidenced by significant recovery of the proliferative capacity of PBMC after removal of the parasite-containing inserts. Moreover, the extent of the suppression produced by trypanosomal immunosuppressive factor subsided as culture time increased. Treatment of trypanosomal immunosuppressive factor with proteases abrogated its suppressive activity, suggesting that the relevant principle(s) was of protein nature. From ultrafiltration experiments, the molecular mass of the suppressive molecule(s) was estimated to be between 30,000 and 100,000 Da. These results demonstrate for the first time the capacity of T. cruzi to spontaneously secrete a factor that suppresses human lymphocyte responses in vitro. This factor, which may play a role in the down-regulation of host immune function observed in acute chagasic patients, might be a useful tool in exploring the mechanisms that regulate the expression of IL-2R and other surface molecules playing key roles in lymphocyte activation. 相似文献
118.
119.
Background
Genomic imprinting is an epigenetic mechanism that can lead to differential gene expression depending on the parent-of-origin of a received allele. While most studies on imprinting address its underlying molecular mechanisms or attempt at discovering genomic regions that might be subject to imprinting, few have focused on the amount of phenotypic variation contributed by such epigenetic process. In this report, we give a brief review of a one-locus imprinting model in a quantitative genetics framework, and provide a decomposition of the genetic variance according to this model. Analytical deductions from the proposed imprinting model indicated a non-negligible contribution of imprinting to genetic variation of complex traits. Also, we performed a whole-genome scan analysis on mouse body mass index (BMI) aiming at revealing potential consequences when existing imprinting effects are ignored in genetic analysis.Results
10,021 SNP markers were used to perform a whole-genome single marker regression on mouse BMI using an additive and an imprinting model. Markers significant for imprinting indicated that BMI is subject to imprinting. Marked variance changed from 1.218 ×10−4 to 1.842 ×10−4 when imprinting was considered in the analysis, implying that one third of marked variance would be lost if existing imprinting effects were not accounted for. When both marker and pedigree information were used, estimated heritability increased from 0.176 to 0.195 when imprinting was considered.Conclusions
When a complex trait is subject to imprinting, using an additive model that ignores this phenomenon may result in an underestimate of additive variability, potentially leading to wrong inferences about the underlying genetic architecture of that trait. This could be a possible factor explaining part of the missing heritability commonly observed in genome-wide association studies (GWAS). 相似文献120.
Timothy M Beissinger Guilherme JM Rosa Shawn M Kaeppler Daniel Gianola Natalia de Leon 《遗传、选种与进化》2015,47(1)