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331.
The advent of nuclear reactors ushered in an era of increasing number of sources of ionizing radiations. However, the potential
of ionizing radiations to cause harmful effects was recognized soon after the discovery of x-rays and radioactivityi.e. long before the building of nuclear reactors. Therefore, protection against ionizing radiations has been of paramount concern
and has guided the development of atomic energy and related fields. The advances in technology in general resulted in an increase
in accidents causing injury and death. It was realised that even medicines, food additives and a host of other substances
of daily use had injurious side effects. Smoking was found to be extremely harmful. From these emerged the concepts of quantitative
and relative risks. This article discusses briefly the concept of riskvis-a-vis ionizing radiations and approaches to protection against them. 相似文献
332.
J. Spiliotis 《Applied Mathematics and Optimization》1997,35(3):265-282
The complex parabolic type Monge-Ampère equation we are dealing with is of the form
inB × (0,T),u=ϕ on Γ, whereB is the unit ball in ℂ
d
,d>1, and Γ is the parabolic boundary ofB × (0,T). Solutionu is proved unique in the class
. 相似文献
333.
Oscillation for systems of nonlinear neutral type parabolic partial functional differential equations 总被引:14,自引:0,他引:14
YANGJUN GUANXINPING 《高校应用数学学报(英文版)》1997,12(2):165-178
This paper discusses the oscillation of solutions for systems of nonlinear neutral type parabolic partial fuctional differential equations of the form 相似文献
334.
Itaru SatoKousuke Kadowaki Hiroki UrabeJong Hwa Jung Yoshiyuki OnoSeiji Shinkai Kenso Soai 《Tetrahedron letters》2003,44(4):721-724
Highly enantiomerically enriched (up to 96-97% ee) 5-pyrimidyl alkanol was obtained by the addition of diisopropylzinc to pyrimidine-5-carbaldehyde in the presence of the artificially designed chiral inorganic material, right- and left-handed helical silica. 相似文献
335.
Chiral lactate-derived allyltrichlorostannanes reacted with chiral α-methyl β-alkoxy and syn and anti α-methyl-β-alkoxy aldehydes to give the corresponding homoallylic alcohols with moderate to high 1,4-syn-diastereoselectivities. 相似文献
336.
设计了以淬发方式产生强流电子的4 MeV 直线感应加速器的基于局域网的分布式控制系统。介绍了应用FP2000分布式I/O系统和可编程序电源的硬件体系结构,阐述了在Labwindows/CVI平台上基于DataSocket服务器作为数据传输媒介的分布式系统实现方法。对系统开发中出现的DataSocket服务器数据丢失,因数据项数量庞大而带来应用程序的结构和逻辑关系难于把握两点不足,提出了对数据项进行抽象和综合,应用数据字典描述数据项,充分考虑可靠性和快速响应之间的关系,合理使用数据项的属性等有效的实现办法。 相似文献
337.
We consider two-dimensional Ising models bounded by general parabolic curves and study their transfer matrices and associated quantum spin chains. We derive their eigenvalue spectra numerically and analytically, both at the critical point and in its vicinity. From this we find how the geometrical form of the system is reflected in the spectrum and how it influences the critical behaviour near the tip. 相似文献
338.
339.
Zhen QIAO Xue Yan SHI Qing Hua BIAN Shi Cong HOU Min WANG* Shandong Pesticide Research Institute Jinan College of Sciences China Agricultural University Beijing 《中国化学快报》2004,15(9)
Bis(oxazoline) ligands1 have been successfully used in a variety of metal-catalyzed asymmetric reactions, such as cyclopropanation, allylic oxidation reactions, etc; Chiral ferrocene derivatives2 have also been proved as effective ligands in numerous asymmetric reactions, for example, chiral ferrocenylphosphines exhibited high enantioselectivity for the reduction of olefins, Heck reactions and Aldol reactions of aldehydes. These results stimulated us to study the behaviour the bis(oxazoline) … 相似文献
340.
制备了Fe/Si O2/PDMS颗粒填充固相萃取柱,并建立了固相萃取/在线热解吸-气相色谱联用测定水样中痕量苯系物的分析方法。采用电磁感应加热技术在线热解吸固相萃取柱富集的苯系物,并直接引入气相色谱进样口进行分离定量。各苯系物在0.1~20 ng/L范围内线性关系良好,其相关系数(r)为0.999 2~0.999 6,对1 ng/L各苯系物测定的相对标准偏差(RSD,n=11)为2.0%~4.4%,检出限为0.03~0.05 ng/L。 相似文献