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1.
The occurrence and frequency of 2n pollen in 2x, 4x,and 6x wild,tuber-bearing Solanum species from Mexico,and Central and South America 总被引:1,自引:0,他引:1
K. Watanabe S. J. Peloquin 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1991,82(5):621-626
Summary The occurrence of 2n pollen-producing plants was investigated in 187 plant introductions (PIs) of 38 wild species of tuber-bearing Solanum. These 2x, 4x, and 6x species are from Mexico, and Central and South America. The determination of 2n pollen-producing plants was conducted using acetocarmine glycerol. Plants with more than 1% large-size pollen were regarded as 2n pollen-producing plants. 2n pollen-producing plants were identified in the following species: 10 out of 12 Mexican 2x species, seven of nine South American 2x species, seven of seven Mexican and Central American 4x species, five of five South American 4x species, and five of five Mexican 6x species. The frequency of 2n pollen-producing plants varied among species at the same ploidy level, but the range of frequency, generally between 2 and 10% among species, was similar over different ploidy levels. The general occurrence of 2n pollen in both 2x and polyploid species, which are evolutionarily related, is evidence that the mode of polyploidization in tuber-bearing Solanums is sexual polyploidization. Furthermore, the frequencies of 2n pollen-producing plants in autogamous disomic polyploid species were not markably different from those of their related diploid species. It is thought that the frequent occurrence of 2n gametes with autogamy tends to disturb the fertility and consequently reduce fitness of polyploids. Thus, we propose that the breeding behavior of polyploids and the occurrence of 2n gametes may be genetically balanced in order to conserve high fitness in polyploid species in tuberbearing Solanum.Paper No. 3114 from the Laboratory of Genetics. Research supported by the College of Agriculture and Life Sciences; International Potato Center; USDA, SEA, CGRO 84-CRCR-1-1389; and Frito Lay, Inc. 相似文献
2.
E. L. Camadro S. J. Peloquin 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1980,56(1-2):11-15
Summary A group of wild, tuber-bearing species from Northwest Argentina, belonging to the series Tuberosa, Solarium spegazzini Bitt. (spg, 2n=2x=24), S. gourlayi Hawkes (grl, 2n=2x=24 and 2n=4x=48) and S. oplocense Hawkes (opl, 2n=6x=72), and Cuneolata, S. infundibuliforme Phil (ifd, 2n=2x=24), is being used to investigate the mode of origin of polyploids in the genus Solanum. 2n gametes have been detected in the diploid species ifd and spg and in a diploid race of grl, using cytological and breeding approaches. Twenty-two introductions of spg, 8 of grl and 26 of ifd have been tested for 2n pollen; 59%, 63% and 54% of them, respectively, had at least one 2n pollen producing plant. These introductions comprised 238, 76 and 235 plant respectively, of which 20, 16, and 32 plant produced 5% or more 2n pollen. The mechanism of 2n pollen formation was determined in several plant of 2x spg, 2x grl and 2x ifd. All of them were found to form diplandroids via parallel spindles. This mechanism, which gives meiotic products genetically equivalent to first division restitution gametes, is under control of the Mendelian recessive ps. The results suggest that the allele ps is widely distributed in natural populations of the three diploids, and that its frequency is very high. These species are seen as valuable material for population genetic studies, and for the eventual incorporation into a breeding scheme involving sexual polyploidization via 2n gametes. 相似文献
3.
Rosenthal IM Zhang M Williams KN Peloquin CA Tyagi S Vernon AA Bishai WR Chaisson RE Grosset JH Nuermberger EL 《PLoS medicine》2007,4(12):e344
Background
Availability of an ultra-short-course drug regimen capable of curing patients with tuberculosis in 2 to 3 mo would significantly improve global control efforts. Because immediate prospects for novel treatment-shortening drugs remain uncertain, we examined whether better use of existing drugs could shorten the duration of treatment. Rifapentine is a long-lived rifamycin derivative currently recommended only in once-weekly continuation-phase regimens. Moxifloxacin is an 8-methoxyfluoroquinolone currently used in second-line regimens.Methods and Findings
Using a well-established mouse model with a high bacterial burden and human-equivalent drug dosing, we compared the efficacy of rifapentine- and moxifloxacin-containing regimens with that of the standard daily short-course regimen based on rifampin, isoniazid, and pyrazinamide. Bactericidal activity was assessed by lung colony-forming unit counts, and sterilizing activity was assessed by the proportion of mice with culture-positive relapse after 2, 3, 4, and 6 mo of treatment. Here, we demonstrate that replacing rifampin with rifapentine and isoniazid with moxifloxacin dramatically increased the activity of the standard daily regimen. After just 2 mo of treatment, mice receiving rifapentine- and moxifloxacin-containing regimens were found to have negative lung cultures, while those given the standard regimen still harbored 3.17 log10 colony-forming units in the lungs (p < 0.01). No relapse was observed after just 3 mo of treatment with daily and thrice-weekly administered rifapentine- and moxifloxacin-containing regimens, whereas the standard daily regimen required 6 mo to prevent relapse in all mice.Conclusions
Rifapentine should no longer be viewed solely as a rifamycin for once-weekly administration. Our results suggest that treatment regimens based on daily and thrice-weekly administration of rifapentine and moxifloxacin may permit shortening the current 6 mo duration of treatment to 3 mo or less. Such regimens warrant urgent clinical investigation. 相似文献4.
Electron paramagnetic resonance (EPR) spectroscopy has often played a crucial role in characterizing the various cofactors and processes of photosynthesis, and photosystem II and its oxygen evolving chemistry is no exception. Until recently, the application of EPR spectroscopy to the characterization of the oxygen evolving complex (OEC) has been limited to the S2-state of the Kok cycle. However, in the past few years, continuous wave-EPR signals have been obtained for both the S0- and S1-state as well as for the S2 (radical)(Z)-state of a number of inhibited systems. Furthermore, the pulsed EPR technique of electron spin echo electron nuclear double resonance spectroscopy has been used to directly probe the 55Mn nuclei of the manganese cluster. In this review, we discuss how the EPR data obtained from each of these states of the OEC Kok cycle are being used to provide insight into the physical and electronic structure of the manganese cluster and its interaction with the key tyrosine, Y(Z). 相似文献
5.
Meiotic mutants in potato. Valuable variants 总被引:5,自引:0,他引:5
6.
We discovered Zeocin™ is an effective antibiotic against Enterobacter agglomerans and Klebsiella pneumoniae strains isolated from the walnut husk fly (Rhagoletis completa Cresson: Family Tephritidae) and that bleomycin resistance can be used as a selective marker in transforming plasmids. We
transformed Ent. agglomerans and K. pneumoniae strains originally isolated from their close association with R. completa gut to produce enhanced green fluorescent protein, a variant of green fluorescent protein in the first demonstration of genetic
transformation of internal extracellular bacteria isolated from a tephritid pest. We report methods for plasmid-mediated transformation
of these bacteria, the expression of fluorescent marker protein from the transforming plasmids, and the stability of the transforming
plasmid in the bacteria. We also discuss applications of this technology in the study of pest biology and control implementation.
Received: 5 November 1999 / Accepted: 15 December 1999 相似文献
7.
Britt RD Campbell KA Peloquin JM Gilchrist ML Aznar CP Dicus MM Robblee J Messinger J 《Biochimica et biophysica acta》2004,1655(1-3):158-171
The pulsed electron paramagnetic resonance (EPR) methods of electron spin echo envelope modulation (ESEEM) and electron spin echo-electron nuclear double resonance (ESE-ENDOR) are used to investigate the structure of the Photosystem II oxygen-evolving complex (OEC), including the paramagnetic manganese cluster and its immediate surroundings. Recent unpublished results from the pulsed EPR laboratory at UC-Davis are discussed, along with aspects of recent publications, with a focus on substrate and cofactor interactions. New data on the proximity of exchangeable deuterons around the Mn cluster poised in the S(0)-state are presented and interpreted. These pulsed EPR results are used in an evaluation of several recently proposed mechanisms for PSII water oxidation. We strongly favor mechanistic models where the substrate waters bind within the OEC early in the S-state cycle. Models in which the O-O bond is formed by a nucleophilic attack by a Ca(2+)-bound water on a strong S(4)-state electrophile provide a good match to the pulsed EPR data. 相似文献
8.
am Ende CW Knudson SE Liu N Childs J Sullivan TJ Boyne M Xu H Gegina Y Knudson DL Johnson F Peloquin CA Slayden RA Tonge PJ 《Bioorganic & medicinal chemistry letters》2008,18(10):3029-3033
Previous structure-based design studies resulted in the discovery of alkyl substituted diphenyl ether inhibitors of InhA, the enoyl reductase from Mycobacterium tuberculosis. Compounds such as 5-hexyl-2-phenoxyphenol 19 are nM inhibitors of InhA and inhibit the growth of both sensitive and isoniazid-resistant strains of Mycobacterium tuberculosis with MIC(90) values of 1-2 microg/mL. However, despite their promising in vitro activity, these compounds have ClogP values of over 5. In efforts to reduce the lipophilicity of the compounds, and potentially enhance compound bioavailability, a series of B ring analogues of 19 were synthesized that contained either heterocylic nitrogen rings or phenyl rings having amino, nitro, amide, or piperazine functionalities. Compounds 3c, 3e, and 14a show comparable MIC(90) values to that of 19, but have improved ClogP values. 相似文献
9.
Acute myeloid leukemia (AML) is a heterogeneous clonal disorder of myeloid precursors arrested in their maturation, creating a diverse disease entity with a wide range of responses to historically standard treatment approaches. While signifi cant progress has been made in characterizing and individualizing the disease at diagnosis to optimally inform those affected, progress in treatment to reduce relapse and induce remission has been limited thus far. In addition to a brief summary of the factors that shape prognostication at diagnosis, this review attempts to expand on the current therapies under investigation that have shown promise in treating AML, including hypomethylating agents, gemtuzumab ozogamicin, FLT3 tyrosine kinase inhibitors, antisense oligonucleotides, and other novel therapies, including aurora kinases, mTOR and PI3 kinase inhibitors, PIM kinase inhibitors, HDAC inhibitors, and IDH targeted therapies. With these, and undoubtedly many others in the future, it is the hope that by combining more accurate prognostication with more effective therapies, patients will begin to have a different, and more complete, outlook on their disease that allows for safer and more successful treatment strategies. 相似文献
10.
George L. Drusano Michael Neely Michael Van Guilder Alan Schumitzky David Brown Steven Fikes Charles Peloquin Arnold Louie 《PloS one》2014,9(7)