نتایج جستجو برای: sulfur s t
تعداد نتایج: 1332969 فیلتر نتایج به سال:
The bonding of sulfur to surfaces of gold is an important subject in several areas of chemistry, physics, and materials science. Synchrotron-based high-resolution photoemission and first-principles density-functional (DF) slab calculations were used to study the interaction of sulfur with a well-defined Au(111) surface and polycrystalline gold. Our experimental and theoretical results show a co...
Thioctic acid labeled with sulfur-35 has been p repa red and i t s metabol ism b y algae has been studied. It i s converted by the algae into a number of f o r m s , all of which upon hydrolysis yield either the disulfide o r i t s sulfoxide. One of these constituted the major portion of the labeled ma te r i a l in the chlorop1;~sts . Aerobic metabolism for some minutes i s required to produce...
به ازای اعداد صحیح نامنفی r،s،t یک [r,s,t] –رنگ آمیزی گراف g=(v(g),e(g))، نگاشتی است مثل c ازاجتماع v(g) ?e (g) به مجموعه رنگ های {k-1 ،...،1،0} به طوری که : 1.برای هر دو راس مجاور vi وr vj ? | c(vi)-c(vj) | .2برای هر دو یال مجاور ei وej s ? | c(ei)-c(ej) | .3برای همه ی جفت راس ها و یال های هم وقوع t ? | c(vi)-c(ej) | عدد رنگی [r,s,t] ، r,s,t(g)? ،گراف g عبارتست از کوچک ترین عدد k به طوری...
رنگ آمیزی یکی از زمینه های مهم در نظریه گراف است. رنگ آمیزی های متعددی برای گراف ها وجود دارد، به عنوان مثال می توان به رنگ آمیزی های رأسی، یالی و کلی اشاره نمود. در سال 2002، هاکمن و دیگران مفهوم [r,s,t]- رنگ آمیزی را معرفی کردند. گراف (g=(v,e با مجموعه رأس های g و مجموعه یال های e و اعداد صحیح نامنفی r,s,t را در نظر بگیرید. یک [r,s,t]- رنگ آمیزی با k رنگ یک نگاشت مانند c از (v(g)?e(g به مجموع...
in order to evaluate the effect of increasing soil soluble phosphorus (p) and its effect on nitrogen (n) and p uptake, p uptake efficiency and p harvest index of black seed (nigella sativa l.) in a calcareous soil; a field experiment was conducted as factorial layout based on a randomized complete block design with three replications at research station, faculty of agriculture, ferdowsi univers...
Hydrophilic sulfur sols prepared from sodium thiosulfate and concentrated sulfuric acid and purified by repeated NaCl precipitation and peptization in water have been studied by chemical analysis, vibrational spectroscopy, ion-pair chromatography and reversed-phase HPLC. The composition of the sol is Na1 6 4S2 8 .606 • 5.9In S„ • 1.0 NaCl. The elemental sulfur S„ (n = 6 1 4 ; mainly S8) account...
Isotopic compositions of sulfur and concentrations of sulfur and carbon have been measured for sedimentary rocks across terrestrial Cretaceous-Tertiary (K-T) boundary successions that originated from flood-plain and backswamp environments. Organic carbon contents are relatively constant below the boundary (26 cm for the Dogie Creek section and 9 cm for the Brownie Butte section), but change abr...
An unprecedented [4Fe-4S] iron-sulfur cluster was found in RumA, the enzyme that methylates U1939 in Escherichia coli 23 S ribosomal RNA (Agarwalla, S., Kealey, J. T., Santi, D. V., and Stroud, R. M. (2002) J. Biol. Chem. 277, 8835–8840; Lee, T. T., Agarwalla, S., and Stroud, R. M. (2004) Structure 12, 397–407). Methyltransferase reactions do not involve a redox step. To understand the structur...
An unprecedented [4Fe-4S] iron-sulfur cluster was found in RumA, the enzyme that methylates U1939 in Escherichia coli 23 S ribosomal RNA (Agarwalla, S., Kealey, J. T., Santi, D. V., and Stroud, R. M. (2002) J. Biol. Chem. 277, 8835-8840; Lee, T. T., Agarwalla, S., and Stroud, R. M. (2004) Structure 12, 397-407). Methyltransferase reactions do not involve a redox step. To understand the structur...
Soils in many parts of the world are contaminated with heavy metals, leading to multiple, deleterious effects on plants and threats to world food production efficiency. Cadmium (Cd) is one such metal, being toxic at relatively low concentrations as it is readily absorbed and translocated in plants. Sulfur-rich compounds are critical to the impact of Cd toxicity, enabling plants to increase thei...
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