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981.
本文介绍广西计算中心和广西区防疫站合作研制的冷库温度自动记录录仪,文中着重介绍其软硬件设计和主要功能。该记录仪性能/价格比优于国外同类产品,可以用来代替进口产品。  相似文献   
982.
A Fabry-Perot interferometer, funded by the Meridian Project in China, was deployed at the Xinglong station (40.2°N,117.4°E) of the National Astronomical Observatories in Hebei Province, China. The instrument has been operating since April 2010, measuring mesospheric and thermospheric winds. The first observational data of winds at three heights in the mesosphere and thermosphere were analyzed, demonstrating the capacity of this instrument to aid basic scientific research. The wavelengths of three airglow emissions were OH892.0, OI 557.7, and OI 630.0 nm, which corresponded to heights of 87, 98, and 250 km, respectively. Three 38-day data sets of horizontal winds, from April 5, 2010 to May 12, 2010, show clear day-to-day variations at the same height. The minimum and maximum meridional winds at heights of 87, 98, and 250 km were –16.5 to 8.7 m/s, –24.4 to 15.9 m/s, and –43.6 to 1.5 m/s. Measurements of zonal winds were –5.4 to 7.6 m/s, 2.3 to 23.0 m/s, and –22.6 to 49.3 m/s. The average data from the observations was consistent with the data from HWM93. The wind data at heights of 87 and 98 km suggest a semi-diurnal oscillation, clearly consistent with HWM93 results. Conversely there was a clear discrepancy between the observations and the model at 250 km. In general, this Fabry-Perot interferometer is a useful ground-based instrument for measuring mesospheric and thermospheric winds at middle latitudes.  相似文献   
983.
Expression vector pBPC102, which carries winged bean lysine-rich protein (wblrp) gene and dihydropicolinate synthase (DHDPS) gene, was transferred into hexaploid winter wheat cv. Jinghua No.l, Jing411, You899 and Yangnongl5 explants of immature inflorescence and immature embryos by particle bombardment. More than 100 transgenic plants were obtained under the selection of s-(2-aminoethyl)-L-cysteine (AEC). Confirmed transgenic plants of To and TI generation by PCR and PCR-Southern blotting analyses showed successful integration of wblrp gene into wheat genome. Analysis of transgenic plant lines of T2 by Northern dot-blotting showed good expression of wblrp gene in offspring seed. The content of free lysine in leaves, contents of bound lysine and total proteins in seeds of T2 transgenie wheat lines were determined and analyzed. Among 34 tested transgenic lines, levels of free lysine content in leaves of 9 transgenic lines are 2~3times higher than un-trans-formed wild-type cultivars. Among 17 analyzed transgenic lines, bound lysine content of 4 transgenic lines is more than 10% higher than that of wild-type cultivars. Our research suggests that introducing wblrp gene into wheat is an effective way to improve its nutrition quality.  相似文献   
984.
IEEE802.11规范包括MAC子层和物理层(PHY)两个协议层,支持结点的移动通信。很多切换机制的改进算法都以减少切换时间为目的,而随着无线传输的QoS要求和网络通信的速率不断提高,负载对AP切换的影响也日益显著。详细讨论了现有的基于负载的AP切换机制,并对各自的性能进行了分析比较,认为在高负载环境下,采用中心结构的切换机制会比基础结构的切换机制更具优势。  相似文献   
985.
Hypocrellins, as a kind of novel phototherapeutic agents, have several advantages over the clinically used hematoporphyrin derivatives, including high-excited triplet state yield, high phototoxicity, low dark toxicity, and rapid metabolism. However, they exhibit little absorption in the photodynamic window (600--900 nm) and are not water soluble, which limits their application in photodynamic therapy. Sulfonated and metal-ioned hypocrellins have been designed and synthesized to improve their water solubility.Unfortunately, the water-soluble derivatives obtained exhibit lower photodynamic activity than the parent hypocrellins.Thiolated and aminated hypocrellins have also been designed and synthesized to enlarge their photoresponse. Among them,the aminated hypocrellins possess the highest photodynamic activity. We recently have further designed and synthesized some amphiphilic aminated hypocrellin derivatives. Thus,not only the photoresponse but also the water solubility is enhanced. The experiments in vitro and in vivo on the derivatives are under way at present.  相似文献   
986.
金属有机聚合物一般通过金属有机化合物单体聚合来制备,但由于单体制备困难、性能不稳定,其发展受到限制.本文提出了用低压直流电弧等离子喷射法将有机单体和金属直接合成金属有机聚合物薄膜的方法,成功地制备了铜与丙烯腈、丙炔腈的金属有机聚合物薄膜.红外光谱和电子能谱的分析结果表明:聚合物薄膜中含有环状共轭结构,铜与聚合物以共价键、配位键结合.用改进的四探针法进行测量,铜与丙炔腈聚合物薄膜的电阻率在10~0~10~3Ω·cm范围内,铜与丙烯腈聚合物薄膜的电阻率在10~6~10~7Ω·cm范围内。  相似文献   
987.
As的用法在国内外的语法书及文章中已有阐述.但看法不很一致.有的只讲用法,不讲语法 功能,有的不是由浅入深,由表及里,使初学者难以理解.根据个人的教学经验,本文从副词到连 接词、关系代词、关系副词、介词,从As演变展开叙述,俾能有助于教学研究。  相似文献   
988.
以高性能单片机为核心,结合大规模可编程逻辑器件和在系统编程技术,设计了脉动真空灭菌控制系统的硬件和软件;采用模糊信息融合方法,设计了自适应模糊控制策略;针对包裹类灭菌物品,对系统进行了仿真试验研究,研究结果表明系统具有较好的控制效果和较强的抗干扰能力。  相似文献   
989.
The microstructure and mechanical properties of Ti-3.5Al-5Mo-6V-3Cr-2Sn-0.5Fe high strength titanium alloy sheets prepared by unidirectional cold rolling and two-step cross cold rolling were investigated. Results showed that the β phase grains were refined significantly by cold rolling followed by solution treatment for a short time.Compared to unidirectional cold rolling, the short time solution treatment after two-step cross rolling could significantly reduce the non-uniformity of the microstructure of the alloy sheets. After aging treatment at 550 ℃,the anisotropy of the mechanical properties still existed in the unidirectional rolled sheets, and the tensile strength was highest along the rolling direction. After solution and aging treatment, the anisotropy of the mechanical properties of the two-step cross rolling process sheet was not obvious than unidirectional cold rolling,and alloy had good strength and plasticity matching.  相似文献   
990.
高压旋喷技术近几年开始应用于污染土壤修复,对所注入药剂的迁移扩散规律尚不明确,导致工程实践中缺乏可靠依据,同时为克服常规试验测试手段的不足,使用透明土材料开展了污染土修复药剂迁移的室内试验和数值模拟。在考虑分子扩散、机械弥散、对流等耦合情况下,建立了探究药剂在土壤中迁移特性的对流-弥散模型。研究结果表明:透明土试验技术能够直观地显示药剂迁移过程,可以应用于污染土修复药剂迁移特性的研究。在不同土壤压力条件下,存在最佳泥饼高度;相同土壤压力,泥饼高度越高,同一位置处浓度最大值越小;泥饼高度的选取关系到高压旋喷参数的设定,对修复效果及效率有重要影响。药剂的迁移以竖向迁移为主,水平向迁移不明显,因此为保证药剂以较高的浓度迁移至泥饼边缘,应使药剂在泥饼间隙水平方向上分布有较高且均匀的初始浓度。  相似文献   
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