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1.
C. L. Keith R. L. Bridges L. R. Fina K. L. Iverson J. A. Cloran 《Archives of microbiology》1978,118(2):169-172
Anaerobic rupture of the benzoic acid ring was investigated. Carbon 4 was converted primarily to carbon dioxide. Following ring rupture during methane fermentation, propanoic acid is an intermediate, and carbon 4 of benzoate becomes its carboxyl.Contribution No. 1285-j, Division of Biology, Kansas State University, Manhattan, KS 66506. This work was supported in part by funds from the Kansas Agricultural Experiment Station, Kansas State University, Manhattan, KS 66506. Paper II of this series is Fina and Fiskin (1960) 相似文献
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Reaction of DNA with K2PdCl4 at pH 2.0 followed by a piperidine workup produces specific cleavage at adenine (A) residues. Product analysis revealed the K2PdCl4 reaction involves selective depurination at adenine, affording an excision reaction analogous to the other chemical DNA sequencing reactions. Adenine residues methylated at the exocyclic amine (N6) react with lower efficiency than unmethylated adenine in an identical sequence. This simple protocol specific for A may be a useful addition to current chemical sequencing reactions. 相似文献
6.
Suppression and contrasuppression in the induction of contact sensitivity by the administration of cellbound antigen-antibody complexes 总被引:1,自引:0,他引:1
W Ptak M Bereta M Ptak G M Iverson D R Green 《Journal of immunology (Baltimore, Md. : 1950)》1985,135(4):2312-2318
The tolerogenic signal produced by the i.v. injection of haptenated peritoneal exudate cells can be converted to an immunogenic signal by treating the cells with antibody to the hapten before administration. We examined this phenomenon and found that immunity induced by antigen-antibody complexes, as opposed to skin sensitization, is resistant to suppressor T cell influences. This resistance to suppression is due to the activation of an I-J+, Ly-1 T cell population which adheres to the Vicia villosa lectin, all characteristics of contrasuppressor T cells. Because haptenated cells can induce immunity if injected subcutaneously or into cyclophosphamide-pretreated recipients (thereby avoiding the induction of suppressor cells), we suggest that the activation of contrasuppressor cells by antigen-antibody complexes overrides suppressive influences in the host, allowing immunity to become dominant. The possible roles of suppression and contrasuppression in channeling the effector arm of the immune response (e.g., contact sensitivity vs humoral immunity) are discussed. 相似文献
7.
MAJOR CLADES OF THE ANGIOSPERMS 总被引:2,自引:0,他引:2
ROLF DAHLGREN KÅRE BREMER 《Cladistics : the international journal of the Willi Hennig Society》1985,1(4):349-368
Abstract— Our knowledge of fundamental angiosperm interrelationships is still very incomplete. The absence of a narrowly circumscribed gymnosperm outgroup, ideally the sister group, makes character evaluation, necessary for a cladistic analysis, difficult. According to current views the superorder Magnoliiflorae with a number of other groups, for example the monocotyledons, may represent a complex of families near the base of the angiosperms. Interrelationships of groups within the monocotyledons are much better understood than those between groups within the dicotyledons. A cladogram of monocotyledon orders based on earlier work by R. Dahlgren, H. T. Clifford, and F. N. Rasmussen is presented. A data matrix for a sample of the angiosperms with 61 characters for 49 taxa, mostly magnoliifloran and related families, is presented. The characters are polarized mainly according to the current view that the primitive angiosperm morphotype is a woody dicotyledon with strobiloid flowers. As an alternative the matrix is adjusted following W. C. Burger's conjecture that the primitive angiosperm was a herbaceous monocotyledon with trimerous flowers. Both matrices were run in a computerized parsimony analysis, resulting in numerous equally parsimonious solutions. This result is illustrative of the great homoplasy in the available character information, and also of how little actually is known about fundamental angiosperm interrelationships or phylogeny. 相似文献
8.
Assignment of orthologous relationships among mammalian alpha-globin genes by examining flanking regions reveals a rapid rate of evolution 总被引:1,自引:0,他引:1
In order to study the relationships among mammalian alpha-globin genes, we
have determined the sequence of the 3' flanking region of the human alpha 1
globin gene and have made pairwise comparisons between sequenced
alpha-globin genes. The flanking regions were examined in detail because
sequence matches in these regions could be interpreted with the least
complication from the gene duplications and conversions that have occurred
frequently in mammalian alpha-like globin gene clusters. We found good
matches between the flanking regions of human alpha 1 and rabbit alpha 1,
human psi alpha 1 and goat I alpha, human alpha 2 and goat II alpha, and
horse alpha 1 and goat II alpha. These matches were used to align the
alpha-globin genes in gene clusters from different mammals. This alignment
shows that genes at equivalent positions in the gene clusters of different
mammals can be functional or nonfunctional, depending on whether they
corrected against a functional alpha-globin gene in recent evolutionary
history. The number of alpha-globin genes (including pseudogenes) appears
to differ among species, although highly divergent pseudogenes may not have
been detected in all species examined. Although matching sequences could be
found in interspecies comparisons of the flanking regions of alpha- globin
genes, these matches are not as extensive as those found in the flanking
regions of mammalian beta-like globin genes. This observation suggests that
the noncoding sequences in the mammalian alpha-globin gene clusters are
evolving at a faster rate than those in the beta-like globin gene clusters.
The proposed faster rate of evolution fits with the poor conservation of
the genetic linkage map around alpha-globin gene clusters when compared to
that of the beta-like globin gene clusters. Analysis of the 3' flanking
regions of alpha-globin genes has revealed a conserved sequence
approximately 100-150 bp 3' to the polyadenylation site; this sequence may
be involved in the expression or regulation of alpha-globin genes.
相似文献
9.
The pattern of genetic differentiation among experimental populations of the flour beetle Tribolium castaneum suggested the hypothesis that relative fitness of three genotypes at the PGM-1 locus (or other linked loci) depends directly on diet. This hypothesis was tested by measuring several fitness components (developmental time, survival, fecundity, rate of egg cannibalism) on groups of individuals differing at the PGM-1 locus that were reared on three types of flour (wheat, corn and a mixture of wheat, corn, barley and rye). Flour type had large effects on all traits except larval survival to 3 weeks of age. Relative fitnesses of the three genotypes differed significantly for fecundity. Diet was found to significantly influence the relative developmental times of the three genotypes. 相似文献
10.
A method for the detection of starch hydrolysis by bacteria 总被引:2,自引:0,他引:2