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排序方式: 共有64条查询结果,搜索用时 31 毫秒
1.
The fungicide triarimol was tested for its effect on abscisic acid (ABA) accumulation in growing culturesof Cercospora rosicola. ABA accumulation was reduced by approximately 50% with 10–8 M triarimol. Growth ofC. rosicola, as measured by dry weight accumulation, was inhibited by triarimol concentrations at or greater than 10–7 M. These results are compared with those obtained with clomazone, ancymidol, and paclobutrazol, which inhibit ABA accumulation by 50% at concentrations of 5 × 10–5, 5 × 10–6, and 5 × 10–7 M, respectively. Triarimol, therefore, is among the most potent inhibitors of ABA biosynthesis reported to date. Feeding studies with [14C]mevalonic acid confirmed the inhibition of ABA biosynthesis by 5 × 10–8 M triarimol. These results support previous suggestions that one or more of the steps in the ABA biosynthetic pathway from mevalonic acid is catalyzed by cytochrome P-450. Feeding studies with 1-deoxy-[2H]-ABA in resuspended cultures ofC. rosicola show that the conversion of this substrate is not inhibited by triarimol. 相似文献
2.
The alpha-like globin gene cluster in rabbits contains embryonic zeta-
globin genes, an adult alpha-globin gene, and theta-globin genes of
undetermined function. The basic arrangement of genes, deduced from
analysis of cloned DNA fragments, is 5'-zeta 0-zeta 1-alpha 1-theta 1- zeta
2-zeta 3-theta 2-3'. However, the pattern of restriction fragments
containing zeta- and theta-globin genes varies among individual rabbits.
Analysis of BamHI fragments of genomic DNA from 24 New Zealand white
rabbits revealed eight different patterns of fragments containing
zeta-globin genes. The large BamHI fragments containing genes zeta 0 and
zeta 1 are polymorphic in length, whereas a 1.9-kb fragment containing the
zeta 2 gene and the 3.5-kb fragment containing the zeta 3 gene do not vary
in size. In contrast to this constancy in the size of the restriction
fragments, the copy number of the zeta 2 and zeta 3 genes does vary among
different rabbits. No length polymorphism was detected in the BamHI
fragments containing the theta-globin genes, but again the copy number
varies for restriction fragments containing the theta 2 gene. The alpha 1-
and theta 1-globin genes are located in a nonpolymorphic 7.2-kb BamHI
fragment. The combined data from hybridization with both zeta and theta
probes shows that the BamHI cleavage pattern does not vary within the
region 5'-alpha 1-theta 1- zeta 2-zeta 3-theta 2-3', but the pattern
genomic blot-hybridization patterns for the progeny of parental rabbits
with different zeta-globin gene patterns shows that the polymorphic
patterns are inherited in a Mendelian fashion. Two different haplotypes
have been mapped based on the genomic blot-hybridization data. The
variation in the alpha-like globin gene cluster in the rabbit population
results both from differences in the copy number of the duplication block
containing the zeta-zeta-theta gene set and from the presence or absence of
polymorphic BamHI sites.
相似文献
3.
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
4.
We developed a biphasic culture system consisting of 4 ml of brucella agar (BA) and 6 ml of brucella broth (BB) in 25-cm2 tissue culture flasks, which were incubated in air (BB/BAa) or in a gas mixture of 5% O2, 10% CO2, and 85% N2 (BB/BAg). These media were also used with a supplement consisting of ferrous sulfate, sodium metabisulfite, and sodium pyruvate and incubated as above (FB/FAa and FB/FAg, respectively). Highly satisfactory growth of Campylobacter jejuni 301 was obtained with all medium-gas phase combinations provided that the number of viable cells in the inoculum was large (greater than or equal to 10(6)/ml). The use of FB/FAa permitted the inoculum to be reduced to 100 cells per ml. With an adjusted gas phase (BB/BAg and FB/FAg), near-optimal growth was obtained from an inoculum of 1 to 10 cells per ml. Under most of these conditions the generation time was approximately 90 min. During the logarithmic growth phase, the cells retained their typical spiral morphology and high motility. These media also proved to be highly satisfactory for the cultivation of fresh isolates as well as other stock strains of Campylobacter. When the broth phase of the cultures, after addition of 15% glycerol, was quickly frozen and maintained at -70 degrees C, all strains thus far examined were readily recoverable and satisfactorily cultivated without additional passage. 相似文献
5.
Ronald C. Coolbaugh 《Journal of Plant Growth Regulation》1984,3(1-4):97-109
Cytokinins, which have some structural similarities to ancymidol, a plant growth retardant, were tested for their effects on the cell-free oxidation ofent-kaurene. Results indicate that several cytokinins inhibit this reaction in microsomal extracts of liquid endosperm from immature wild cucumber seeds. N6-cyclohexanemethyladenine was the most active (inhibiting 50% of the controlent-kaurene oxidation at 2×10?6 M). N6-isoamyladenine, N6-benzyladenine, N6-(Δ2-isopentenyl)adenine and dihydrozeatin were active at successively higher concentrations. Zeatin, kinetin, adenine, N6-benzyladenosine, and N6-(isopentenyl)adenosine were inactive in this system. The basis for the inhibition ofent-kaurene oxidation by cytokinins may be similar to that of ancymidol: interaction with cytochrome P-450. A binding spectrum similar to that of ancymidol with cytochrome P-450 from wild cucumber endosperm microsomes was obtained with four active cytokinins. The cytokinin binding properties of this protein are currently under investigation. No metabolism of N6-benzyladenine could be detected under conditions in which the cytokinin inhibited the oxidation ofent-kaurene toent-kaurenol. 相似文献
6.
David M. Dooley Thomas S. Coolbaugh 《Biochemical and biophysical research communications》1980,96(2):823-830
Aqueous Cu2+ and Cu(II) complexes of salicylate, lysine, and tyrosine decrease the rate of benzylamine oxidation by bovine plasma amine oxidase. Bissalicylato Cu(II) and Cu2+ inhibit non-competitively with respect to benzylamine. Lysine, tyrosine, Cu(EDTA)2?, Zn2+, and Co2+ do not inhibit, and erythrocyte Cu, Zn superoxide dismutase shows only slight inhibition of the amine oxidase. The data are most consistent with an inhibitory mechanism involving dismutation of O2? by the Cu(II) complexes within a site relatively inaccessible to the enzyme superoxide dismutase. Excess lysine significantly decreases inhibition by the bis-lysine complex of Cu(II). 相似文献
7.
8.
Out of Africa and back again: nested cladistic analysis of human Y chromosome variation 总被引:18,自引:3,他引:15
Hammer MF; Karafet T; Rasanayagam A; Wood ET; Altheide TK; Jenkins T; Griffiths RC; Templeton AR; Zegura SL 《Molecular biology and evolution》1998,15(4):427-441
We surveyed nine diallelic polymorphic sites on the Y chromosomes of 1,544
individuals from Africa, Asia, Europe, Oceania, and the New World.
Phylogenetic analyses of these nine sites resulted in a tree for 10
distinct Y haplotypes with a coalescence time of approximately 150,000
years. The 10 haplotypes were unevenly distributed among human populations:
5 were restricted to a particular continent, 2 were shared between Africa
and Europe, 1 was present only in the Old World, and 2 were found in all
geographic regions surveyed. The ancestral haplotype was limited to African
populations. Random permutation procedures revealed statistically
significant patterns of geographical structuring of this paternal genetic
variation. The results of a nested cladistic analysis indicated that these
geographical associations arose through a combination of processes,
including restricted, recurrent gene flow (isolation by distance) and range
expansions. We inferred that one of the oldest events in the nested
cladistic analysis was a range expansion out of Africa which resulted in
the complete replacement of Y chromosomes throughout the Old World, a
finding consistent with many versions of the Out of Africa Replacement
Model. A second and more recent range expansion brought Asian Y chromosomes
back to Africa without replacing the indigenous African male gene pool.
Thus, the previously observed high levels of Y chromosomal genetic
diversity in Africa may be due in part to bidirectional population
movements. Finally, a comparison of our results with those from nested
cladistic analyses of human mtDNA and beta-globin data revealed different
patterns of inferences for males and females concerning the relative roles
of population history (range expansions) and population structure
(recurrent gene flow), thereby adding a new sex-specific component to
models of human evolution.
相似文献
9.
Moroni M Coolbaugh TV Lombardini E Mitchell JM Moccia KD Shelton LJ Nagy V Whitnall MH 《Radiation research》2011,176(1):89-101
Additional large animal models for the acute radiation syndrome (ARS) would facilitate countermeasure development. We demonstrate here that Gottingen minipigs develop hematopoietic ARS symptoms similar to those observed in canines, non-human primates (NHPs) and humans. Dosimetry for whole-body γ irradiation (0.6 Gy/min) was performed using electronic paramagnetic resonance (EPR) with alanine; National Institute of Standards and Technology (NIST)-calibrated alanine pellets and water-filled Plexiglas phantoms were used. After irradiations of 1.6-2.0 Gy, blood pancytopenia was observed for several weeks, accompanied by the characteristic ARS stages: prodromal symptoms, latent period, illness and recovery or morbidity. Morbidity occurred between days 14 and 27, with a preliminary LD(50/30) estimate between 1.7 and 1.9 Gy. The criterion of whether platelet counts were <200 × 10(3)/μl 7 days postirradiation predicted whether animals would survive in 18 out of 20 cases. The degree of granulocytosis 3 h postirradiation was inversely correlated with survival. Animals euthanized based on preset morbidity criteria displayed signs of multi-organ dysfunction, including widespread internal hemorrhage and alterations in organ function reflected in blood chemistry. Circulating C-reactive protein (CRP), a marker for inflammation, became elevated within hours after irradiation, subsided after several days, and increased again after 14 days. The results support further development of the Gottingen minipig as a model for ARS. 相似文献
10.