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排序方式: 共有254条查询结果,搜索用时 15 毫秒
81.
Guodong Xu Yubao Sun Rupesh Rohan Yunfeng Zhang Weiwei Cai Hansong Cheng 《Journal of Materials Science》2014,49(17):6111-6117
Lithium poly(pyromellitic acid borate) (PPAB) was synthesized via polymerization of lithium tetramethanolatoborate and silylated pyromellitic acid. The synthesized material was characterized by Fourier transformation infrared spectroscopy, 11B nuclear magnetic resonance, scanning electron microscopy, and thermogravimetric analysis. And electrochemical characterizations were carried out on the blended PPAB/PVDF-HFP membrane. The PPAB-based composite membrane exhibits high lithium ionic conductivity, a broad electrochemical window and a high lithium-ion transference number. The battery cells assembled with the PPAB/PVDF-HFP/EC:PC composite membrane as the electrolyte perform reasonably well not only at elevated temperature but also at room temperature with good cyclability and discharge capacity, making the material suitable for applications in lithium-ion batteries. 相似文献
82.
A. K. Raina J. A. Klun M. Schwarz A. Day B. A. Leonhardt L. W. Douglass 《Journal of chemical ecology》1986,12(1):229-237
Ten C16 chain-length compounds were identified from heptane extracts of ovipositors of female melonworm,Diaphania hyalinata (L.). The major constituents of the extracts were (E)-11-hexadecenal and (E,E)-10,12-hexadecadienal [(E,E)-10,12–16:Ald] and the alcohols and acetates of these olefins were found in trace amounts (<2%). Extracts also contained traces of (E,Z)- and (Z,Z)-10,12-16:Ald, hexadecanal, and 1-hexadecanol. Analysis of the behavioral responses of males to synthetic mixtures of these compounds and responses to ovipositor extracts in a flight tunnel showed that a synthetic mixture of the 10 compounds elicited a behavioral repertoire from males that was indistinguishable from that elicited by ovipositor extract. Flight tunnel studies also indicated that six of the 10 compounds probably represent the essential components of the female's sex pheromone.Supported in part by USDA Cooperative Agreement No. 58-32U4-1-299. Scientific Article No. A-4073, Contribution No. 7058 of the Maryland Agricultural Experiment Station. Mention of a commercial product in this paper does not constitute a recommendation by the U.S. Department of Agriculture. 相似文献
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85.
P Malhotra A Abrol V Kaur S Dhar A Singh S Kaul RK Raina 《Canadian Metallurgical Quarterly》1996,94(9):334-337
A study of prevalence of tuberculosis in Kishtwar tehsil of Jammu region was conducted from June 1991 to May 1992. A total of one thousand two hundred ninety-eight rural as well as urban population suffering from various types of lung diseases was studied for prevalence of tuberculosis and a sizeable number (98) of patients were found to be positive of various types of tuberculosis, viz, pulmonary tuberculosis, tuberculous pleural effusion and miliary tuberculosis. Of the population studied 7.55% were found to be positive for tuberculosis and among them 88.76% patients were anaemic and the commonest type of anaemia was normocytic normochromic and normocytic hypochromic. The ESR was raised in almost of all the patients. Of the population, 80.61% were seen to be positive on skiagram chest and 58.16% were found to be positive on other diagnostic tests like Mantoux's tests, sputum for acid-fast bacilli, etc. Mantoux's test was positive in 27.55% cases and sputum was positive in 30.61% cases. All the cases studied were subjected to special investigations. The changes in parameters are consistent with the diagnosis of tuberculosis. Large family size, poverty, excessive smoking, illiteracy, etc, are the major contributing factors. 相似文献
86.
Rakesh Ranjan Niraj Kumar Rupesh Kumar Pandey M.K. Tiwari 《The International Journal of Advanced Manufacturing Technology》2005,26(7-8):861-869
Feature recognition systems are now widely identified as a cornerstone for conceiving an automated process planning system.
Various techniques have been reported in the literature, but a few of them acquired a status of generic methodology. A flexible
and robust approach is demanded for recognising a wide variety of features, e.g., non-interacting, interacting circular and
slanting features. This research aims to exploit the concept of the ray - firing technique, in which a 2D surface pattern
for each feature is generated and information is extracted from these patterns to correlate it with the corresponding machining
features. The system first defines a virtual surface and then probing rays are dropped from each point of this surface to
the 2.5D features of the B-rep solid model. According to the length of rays between the bottom face of the 2.5D machining
features and the virtual surface, 2D feature patterns are formed for each machining feature. Finally, features are recognised
using an algorithm described in this article. Different types of examples have been considered to demonstrate the effectiveness
of the proposed approach. 相似文献
87.
Attenuation measurements on an Earth space path are presented using a passive microwave radiometer operating at 19.4 GHz in the emission mode. Attenuation measured under clear weather showed variation between 0.2 to 1.1 dB, whereas for cloud conditions attenuation as high as 1.0 dB have been recorded. Attenuation measurements for rain events have been correlated with rainfall rate using a fast-response 10 seconds opto-electronic rain gauge. The values of attenuation versus rainfall rate varied between A (dB)=0.01+0.18 R(mm/h) at the minimum and A (dB)=0.01+0.25 R(mm/h) at the maximum, showing considerable variability in the values of attenuation from year to year. The attenuation statistics for different seasons have also been computed and they show considerable changes from season to season-the largest attenuation in excess of 10 dB recorded in July-August-September, whereas minimum attenuation in excess of 2 dB recorded in December-March for nearly two years of data. Comparison of measurements made over New Delhi with those reported elsewhere show that for 0.02% of time attenuation values lie between those of Slough, England, and Crawford Hill, NJ. The concept of effective path length has been discussed based on the relationship between effective path length and the rain rate 相似文献
88.
Sarabjit Singh O. P. Thakur Chandra Prakash K. K. Raina 《Ferroelectrics Letters Section》2004,31(5):141-148
Structural and thermal properties of PCT ceramics are studied by the substitution of Ta in the titanium site. Samples with compositional formula Pb0.76Ca0.24Mn0.02Ti0.98-5x/4TaxO3 with the variation in x from 0 to 0.04 in steps of 0.01, were prepared by the conventional dry ceramic method. Single-phase formation was confirmed from the X-ray analysis and all the samples show tetragonal structure. Lattice parameters 'c' and 'a' were found to decrease and increase with substitutional parameter x, respectively. Tetragonality (c/a) decreases with increasing Ta content. Dilatometric study was done to analyze the shrinkage behaviour of green and sintered samples. 相似文献
89.
Aganagic M. Awobamise B. Raina G. McCartney A.I. 《Power Systems, IEEE Transactions on》1997,12(3):1229-1236
This paper presents a new model of the generation contingency constrained economic dispatch problem and proposes a method for its solution. The operating policy of Northern Ireland Electricity was the basis for the formulation, and software was implemented to support it. Since the Northern Ireland Electricity power system operates in relative isolation, the operating security criteria are rather stringent. In particular, it is required that loss of generation of any generating unit in the system must be covered by fast, 3 or 30 second generation reserves on other units in the system. The fast response unit reserve capabilities are represented by concave curves. The solution method is based a nonlinear version of Dantzig-Wolfe decomposition principle. Numerical results are presented 相似文献
90.
DsbA and DsbC are involved in protein disulfide bond formation in the periplasm of Gram-negative bacteria. The two proteins are thought to fulfill different functions in vivo, DsbA as a catalyst of disulfide bond formation and DsbC as a catalyst of disulfide bond rearrangement. To explore the basis of this catalytic complementarity, the reaction mechanism of DsbC has been examined using unstructured model peptides that contain only one or two cysteine residues as substrates. The reactions between the various forms of the peptide and DsbC occur at rates up to 10(6)-fold faster than those that involve glutathione and DsbC, and they were constrained to occur at only one sulfur atom of disulfide bonds involving the peptide. Mixed disulfide complexes of DsbC and the peptide were 10(4)-fold more stable than the corresponding mixed disulfides with glutathione. These observations suggest that noncovalent binding interactions occur between the peptide and DsbC, which contribute to the very rapid kinetics of substrate utilization. The interactions between DsbC and the peptide appear to be more substantial than those between DsbA and the same peptide. The differences in the reaction of the peptide at the active sites of DsbA and DsbC provide insight into why DsbC is the better catalyst of disulfide bond rearrangement and how the active site chemistry of these structurally related proteins has been adapted to fulfill complementary functions. 相似文献