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排序方式: 共有122条查询结果,搜索用时 250 毫秒
91.
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T J Bazzett R C Eaton J T Thompson V P Markowski L A Lumley E M Hull 《Life sciences》1991,48(24):2309-2315
This study investigated the effects on genital reflexes of unilateral MPOA injections of 0.1, 1, 3, and 10 micrograms of the D2 agonist quinelorane (LY-163502), and of 3 micrograms quinelorane administered together with 3 micrograms of the D1 antagonist SCH-23390. In addition, the effects of an MPOA injection of 10 micrograms apomorphine were tested. All but the lowest dose of quinelorane significantly decreased the latency to the first reflex. The 3 and 10 micrograms doses of quinelorane, and the combination of quinelorane and SCH-23390, decreased the total number of reflexes. In addition, 10 micrograms quinelorane increased the number of seminal emissions. 10 micrograms apomorphine, like 10 micrograms quinelorane, decreased the latency to the first reflex and increased the number of seminal emissions, but did not decrease the numbers of erections or penile movements. The ratio of D1/D2 activity may influence the number of erections displayed during ex copula testing. 相似文献
94.
95.
Tobamoviruses, mostly isolated from solanaceous plants, may represent
ancient virus lineages that have codiverged with their hosts. Recently
completed nucleotide sequences of six nonsolanaceous tobamoviruses allowed
assessment of the codivergence hypothesis and support a third subgroup
within tobamoviruses. The genomic sequences of 12 tobamoviruses and the
partial sequences of 11 others have been analyzed. Comparisons of the
predicted protein sequences revealed three clusters of tobamoviruses,
corresponding to those infecting solanaceous species (subgroup 1), those
infecting cucurbits and legumes (subgroup 2), and those infecting
crucifers. The orchid-infecting odontoglossum ringspot tobamovirus was
associated with subgroup 1 genomes by its coat and movement protein
sequences, but with the crucifer-pathogenic tobamoviruses by the remainder
of its genome, suggesting that it is the progeny of a recombinant. For four
of five genomic regions, subgroup 1 and 3 genomes were equidistant from a
subgroup 2 genome chosen for comparison, suggesting uniform rates of
evolution. A phylogenetic tree of plant families based on the tobamoviruses
they harbor was congruent with that based on rubisco sequences but had a
different root, suggesting that codivergence was tempered by rare events of
viruses of one family colonizing another family. The proposed subgroup 3
viruses probably have an origin of virion assembly in the movement protein
gene, a large (25-codon) overlap of movement and coat protein open reading
frames, and a comparably shorter genome. Codon-position- dependent base
compositions and codon prevalences suggested that the coat protein frame of
the overlap region was ancestral. Bootstrapped parsimony analysis of the
nucleotides in the overlap region and of the sequences translated from the
-1 frame (the subgroup 3 movement protein frame) of this region produced
trees inconsistent with those deduced from other regions. The results are
consistent with a model in which a no or short overlap organization was
ancestral. Despite encoding of subgroup 2 and 3 movement protein C-termini
by nonhomologous nucleotides, weak similarities between their amino acid
sequences suggested convergent sequence evolution.
相似文献
96.
97.
Gang Li Tianming Liu Ashley Tarokh Jingxin Nie Lei Guo Andrew Mara Scott Holley Stephen TC Wong 《BMC cell biology》2007,8(1):40
Background
Reliable segmentation of cell nuclei from three dimensional (3D) microscopic images is an important task in many biological studies. We present a novel, fully automated method for the segmentation of cell nuclei from 3D microscopic images. It was designed specifically to segment nuclei in images where the nuclei are closely juxtaposed or touching each other. The segmentation approach has three stages: 1) a gradient diffusion procedure, 2) gradient flow tracking and grouping, and 3) local adaptive thresholding. 相似文献98.
Background
Automated identification of cell cycle phases of individual live cells in a large population captured via automated fluorescence microscopy technique is important for cancer drug discovery and cell cycle studies. Time-lapse fluorescence microscopy images provide an important method to study the cell cycle process under different conditions of perturbation. Existing methods are limited in dealing with such time-lapse data sets while manual analysis is not feasible. This paper presents statistical data analysis and statistical pattern recognition to perform this task. 相似文献99.
I. B. Campbell E. W. Collington H. Finch R. Hayes P. Lumley K. Mills N. B. Pike G. M. Robertson I. S. Watts 《Bioorganic & medicinal chemistry letters》1991,1(12):699-704
A series of compounds which possess both thromboxane receptor antagonist and synthase inhibitory activity has been generated by incorporating any arylsulphonamide group into the synthase inhibitors CV4151 and R68070. 相似文献
100.
I. B. Campbell E. W. Collington H. Finch R. Hayes P. Lumley K. Mills G. M. Robertson K. Wharton I. S. Watts 《Bioorganic & medicinal chemistry letters》1991,1(12):695-698
Incorporation of a pyridine miety into amino-prostanoids, previously shown to be thromboxane receptor antagonists, has provided a series of compounds which also show potent thromboxane synthase inhibitory activity. GR 83783, an npropyl-substituted pyridine demonstrates these properties both in vitro and in vivo. 相似文献