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381.
382.
针对传统的温度检测系统对于通信基站测温点少、检测实时性和准确性较低的问题。设计了一种基于DS18B20温度传感器关联性模型的温度检测系统,通过建立不同位置测温值的关联模型,实现对温度异变信号的声光报警和自动处理等功能。该系统以DS18B20温度传感器为核心,设计了温度检测电路、数据关联电路、声光报警电路、继电器控制散热电路等模块。运行证明:本系统相对于传统的温度检测方法,系统的精确性和实时性都有明显改善,为通信基站的安全运行提供了可靠保障。 相似文献
383.
M. Qasim H. Fredrickson P. Honea J. Furey J. Leszczynski S. Okovytyy 《SAR and QSAR in environmental research》2013,24(5):495-515
Highest occupied and lowest unoccupied molecular orbital energies, formation energies, bond lengths and FTIR spectra all suggest competing CL-20 degradation mechanisms. This second of two studies investigates recalcitrant, toxic, aromatic CL-20 intermediates that absorb from 370 to 430?nm. Our earlier study (Struct. Chem., 15, 2004) revealed that these intermediates were formed at high OH? concentrations via the chemically preferred pathway of breaking the C–C bond between the two cyclopentanes, thereby eliminating nitro groups, forming conjugated π bonds, and resulting in a pyrazine three-ring aromatic intermediate. In attempting to find and make dominant a more benign CL-20 transformation pathway, this current research validates hydroxylation results from both studies and examines CL-20 transformations via photo-induced free radical reactions. This article discusses CL-20 competing modes of degradation revealed through: computational calculation; UV/VIS and SF spectroscopy following alkaline hydrolysis; and photochemical irradiation to degrade CL-20 and its byproducts at their respective wavelengths of maximum absorption. 相似文献
384.
A Beckmann Rearrangement/Friedel-Crafts strategy was utilized to prepare 5-amidotetralones in high yield. 相似文献
385.
Aibrohim Dramae Sutichai Nithithanasilp Wilunda Choowong Pranee Rachtawee Samran Prabpai Palangpon Kongsaeree Pattama Pittayakhajonwut 《Tetrahedron》2013
Two new natural products, samroiyotmycins A (1) and B (2), along with two naturally new novclobiocin 101 (3) and 4-hydroxy-3-(3-methylbut-2-enyl)benzamide (5), and five known substances including neoantimycin, clorobiocin (4), 29-O-methylabierixin, daidzein, and 1-(3-indolyl)-2,3-dihydroxypropan-1-one have been isolated from Streptomyces sp. BCC33756. Their chemical structures were determined based on NMR spectral information and the relative stereochemistry of compound 1 was determined by X-ray crystallographic data. Both samroiyotmycins A and B exhibited antimalarial activity against Plasmodium falciparum K1—multi-drug resistant strain, with IC50 values of 3.65 and 3.16 μg/mL, respectively. Compound 1 was inactive against both cancerous (MCF-7, KB) and non-cancerous (Vero) cells, while compound 2 displayed cytotoxicity against Vero cell with IC50 value of 29.57 μg/mL. 相似文献
386.
研究六硝基六氮杂异伍兹烷(CL-20)晶体不同晶型在不同温度下的反应机理, 对于深入认识含能材料在极端条件下的冲击起爆、冲击点火和爆轰过程等具有重要意义. 基于反应力场, 研究水分子在纯α相CL-20及其水合物的晶体结构中数量随时间的变换, 分析水分子对两种体系的初始分解和第二阶段的分解路径的影响. 计算结果表明: CL-20 分子的初始分解路径与水分子无关, 第二阶段的分解反应与水分子有关. 在低温(T<1500 K)下, 水分子对两种体系没有影响, 二者的初始分解路径均为N-NO2键生成NO2自由基; 在1500 K≤T≤2500 K时, 水分子作为反应物或与NO2、、OH自由基等组成催化体系, 生成O2、H2O2等产物, 加速水合物体系在高温下的第二阶段反应, 使得高温下水合物体系的化学反应速率和反应生成的NO2自由基的数量比纯CL-20体系的化学反应速率和反应生成的NO2自由基的数量大; 在T>2500 K时, 水分子的催化反应抑制CL-20初始分解反应, 使得在3000 K时纯CL-20体系的反应速率大于水合物体系中CL-20的反应速率. 相似文献
387.
We improve the range of exponents for the restriction problem for the 3-d paraboloid over finite fields. The key new ingredient is a variant of the Bourgain–Katz–Tao finite field incidence theorem derived from sum-product estimates. In prime order fields, we give an explicit relationship between the exponent in this incidence theorem and restriction estimates for the paraboloid. 相似文献
388.
It is known that an n-dimensional convex body, which is typical in the sense of Baire category, shows a simple, but highly non-intuitive curvature behaviour: at almost all of its boundary points, in the sense of measure, all curvatures are zero, but there is also a dense and uncountable set of boundary points at which all curvatures are infinite. The purpose of this paper is to find a counterpart to this phenomenon for typical convex bodies of given constant width. Such bodies cannot have zero curvatures. A main result says that for a typical n-dimensional convex body of constant width 1 (without loss of generality), at almost all boundary points, in the sense of measure, all curvatures are equal to 1. (In contrast, note that a ball of width 1 has radius 1/2, hence all its curvatures are equal to 2.) Since the property of constant width is linear with respect to Minkowski addition, the proof requires recourse to a linear curvature notion, which is provided by the tangential radii of curvature. 相似文献
389.
We consider both divergence and non-divergence parabolic equations on a half space in weighted Sobolev spaces. All the leading coefficients are assumed to be only measurable in the time and one spatial variable except one coefficient, which is assumed to be only measurable either in the time or the spatial variable. As functions of the other variables the coefficients have small bounded mean oscillation (BMO) semi-norms. The lower-order coefficients are allowed to blow up near the boundary with a certain optimal growth condition. As a corollary, we also obtain the corresponding results for elliptic equations. 相似文献
390.