نتایج جستجو برای: as compered with diploid plants
تعداد نتایج: 10988316 فیلتر نتایج به سال:
cement is an essential ingredient in the concrete buildings. for production of cement considerable amount of fossil fuel and electrical energy is consumed. on the other hand for generating one tone of portland cement, nearly one ton of carbon dioxide is released. it shows that 7 percent of the total released carbon dioxide in the world relates to the cement industry. considering ecological issu...
any change in the refractive index of a laser active medium can lead to serious degradation of beam quality, laser beam modes, laser performance and variation in the intensity distribution. alteration in the refractive index of laser active medium is especially notable in high power lasers. it is clear that in the laser beam production, the pumping agent induces a great amount of heat which...
Hairy root cultures were obtained from diploid and induced tetraploid plants of Datura stramonium and analyzed by gas chromatography/mass spectrometry. Twenty alkaloids (19 for diploid and 9 for tetraploid hairy root cultures) were identified. A new tropane ester 3-tigloyloxy-6-propionyloxy-7-hydroxytropane was identified on the basis of mass spectral data. Hyoscyamine was the main alkaloid in ...
The pollen of five diploid and two tetraploid guayule (Parthenium argentatum Gray) plants was cultured on nutrient media. It was observed that guayule pollen is released as tetrads of spores which will not ger minate on the media unless they are separated into individual pollen grains. For each plant, the results of the germination tests varied with the day and the time of day of the pollen co...
Polyploidy has had a considerable impact on the evolution of many eukaryotes, especially angiosperms. Indeed, most--if not all-angiosperms have experienced at least one round of polyploidy during the course of their evolution, and many important crop plants are current polyploids. The occurrence of 2n gametes (diplogametes) in diploid populations is widely recognised as the major source of poly...
magnetic resonance imaging (mri) is a notable medical imaging technique that makes of phenomenon of nuclear magnetic resonance. because of the resolution and the technology being harmless, mri has considered as the most desirable imaging technique in clinical applications. the visual quality of mri plays an important role in accuracy of medical delineations that can be seriously degraded by exi...
T HAS recently been found that chromosome aberrations of the types I induced by various kinds of radiations occur spontaneously during the development of the pollen grains in diploid species and especially in species hybrids of Tradescantia (GILES 1940). The present studies have shown that the frequency of these aberrations is even higher in triploid Tradescantia hybrids. Furthermore, it has be...
Sexual polyploidization, as a result of 2n gamete formation, is thought to be the main process involved in the origin of polyploid plants (Bretagnolle & Thompson, 1995). These gametes, possessing the somatic rather than the gametophytic chromosome number, can be formed either during microsporogenesis (2n pollen, big pollen, diplandroidy) or megasporogenesis (2n eggs, diplogynoecy). In general, ...
the present study was conducted to investigate the effect of implicit focus on form through input flooding and the effect of noticing, explicit focus on form on linguistic accuracy. to fulfill the purpose of the study, 86 iranian pre-intermediate efl learners of one of the language institutes were chosen by means of administering ket as the homogeneity test. these learners were pretested throug...
Chromosome cytology was examined in two species of the Aster ageratoides complex, A. ageratoides Turcz. (= A. leiophyllus Franch. et Sav.) and A. lasioclada Hayata, in Taiwan. Of the 70 individuals of A. ageratoides sampled, one was found to be diploid (2n = 18) and the rest tetraploid (2n = 36, 37). The occurrence of the diploid A. ageratoides in Taiwan appears to be ancient. Eighteen individu...
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