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51.
Zusammenfassung Es wird ein schneller, transistorisierter Schalter für massive Muskelreizung beschrieben. 相似文献
52.
53.
A. A. Marino Maria Reichmanis R. O. Becker Betsy Ullrich J. M. Cullen 《Cellular and molecular life sciences : CMLS》1980,36(3):309-311
Summary Electromagnetic fields arising from the electrical power system are pervasively present in the environment. To help evaluate their public-health risk we raised 3 successive generations of mice in a low-strength, 60-Hz electric field. We found that the field caused an increased mortality in each generation, and, altered body weights in the 3rd generation.This work was supported by the National Institute of Environmental Health Sciences, Department of Health, Education and Welfare, the Environmental Protection Agency, and the Veterans Administration. 相似文献
54.
55.
Regeneration of the ventricular myocardium in amphibians 总被引:3,自引:0,他引:3
56.
Stimulation of partial limb regeneration in rats 总被引:1,自引:0,他引:1
R O Becker 《Nature》1972,235(5333):109-111
57.
J L Becker J Becker J C Landureau 《Comptes rendus des séances de l'Académie des sciences. Série D, Sciences naturelles》1979,288(18):1403-1406
Hemocytes and non hemocytes in vitro cell lines from Periplaneta americana, have been tested for their ability to incorporate, in the presence of vitamin B 12, various nucleic acid precursors into their DNA. Evidence was shown for enhanced transformation of all ribonucleotides into deoxyribonucleotides in the presence of vitamin B 12. Moreover, in hemocyte cell lines, it was demonstrated that vitamin B 12 produced an activation of thymidine kinase activity. 相似文献
58.
Eyes differ markedly in the animal kingdom, and are an extreme example of the evolution of multiple anatomical solutions to light detection and image formation. A salient feature of all photoreceptor cells is the presence of a specialized compartment (disc outer segments in vertebrates, and microvillar rhabdomeres in insects), whose primary role is to accommodate the millions of light receptor molecules required for efficient photon collection. In insects, compound eyes can have very different inner architectures. Fruitflies and houseflies have an open rhabdom system, in which the seven rhabdomeres of each ommatidium are separated from each other and function as independent light guides. In contrast, bees and various mosquitoes and beetle species have a closed system, in which rhabdomeres within each ommatidium are fused to each other, thus sharing the same visual axis. To understand the transition between open and closed rhabdom systems, we isolated and characterized the role of Drosophila genes involved in rhabdomere assembly. Here we show that Spacemaker, a secreted protein expressed only in the eyes of insects with open rhabdom systems, acts together with Prominin and the cell adhesion molecule Chaoptin to choreograph the partitioning of rhabdomeres into an open system. Furthermore, the complete loss of spacemaker (spam) converts an open rhabdom system to a closed one, whereas its targeted expression to photoreceptors of a closed system markedly reorganizes the architecture of the compound eyes to resemble an open system. Our results provide a molecular atlas for the construction of microvillar assemblies and illustrate the critical effect of differences in a single structural protein in morphogenesis. 相似文献
59.
Transcriptome analysis of Sinorhizobium meliloti nodule bacteria in nifA mutant background 总被引:1,自引:0,他引:1
TIAN Zhexian ZOU Huasong LI Jian ZHANG Yuantao LIU Ying YU Guanqiao ZHU Jiabi RUBERG Silvia BECKER Anke WANG Yiping 《科学通报(英文版)》2006,51(17):2079-2086
Sinorhizobium meliloti is one genus of gram-nega- tive soil bacteria that can fix atmospheric nitrogen in root nodules of its symbiotic leguminous host plants[1]. Specific recognition and progressive differentiation ofboth bacteria and host cells are requ… 相似文献
60.
Jonathan J. Becker 《西北部美国博物学家》2011,46(4)
The Oreana local fauna (Blancan) occurs in exposures of the Glenns Ferry Formation in Owyhee County, Idaho. Fossil birds present include Phalacrocorax cf. P. idahensis, Pelecanus cf. P. halieus, an indeterminate anatid, an indeterminate falconid, two species of Otus , and a species of Colaptes larger than modern C. auratus that provides the earliest record of a colaptine woodpecker. 相似文献