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排序方式: 共有93条查询结果,搜索用时 281 毫秒
61.
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正六月阳光,热辣,闪亮。作物和花草承其德泽,生出灼灼光华。这繁茂的炽烈,闭着眼睛都有炫彩的亮,这就是夏日阳光的王者风范。六月阳光,带来了色彩浓郁到极致的旺盛,六月里诞生的我,感念这火辣阳光赋予的顽强生命力,但还是忍不住悄悄说一点阳光的坏,准确地说,是数落一下赤橙黄绿蓝靛紫的明媚光芒之外, 相似文献
63.
夜间行车,由于自然光线差,照明不佳,导致观察困难、判断时间增长、错漏增多,加上人体机能水平降低,操作可靠性下降,因此发生事故的危险性也随之增大。据统计,某省1995年发生的1169宗重大以上交通事故中,夜间有594宗,占重大以上交通事故总量的50.8%。此外,尽管夜间的交通流量比白天少得多,仅占白天的10%-20%,发生事故的概率却比白天高5~10倍。据美国、前苏联等国家统计,夜间交通事故占交通事故总量的46%~54%(死亡近60%)。因此,充分认识夜间行车特点及其困难,采取相应的安全对策,是一个需溪深入探讨和总结的重要课题。 相似文献
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光污染已经成为继水污染、大气污染、噪声污染、固体废物污染之后的第5大污染,是21世纪直接影响人类健康的又一环境杀手!
城市中,光污染随处可见:建筑物的玻璃幕墙等反射的太阳光线,夜幕下的广告灯、霓虹灯、路灯,舞厅、夜总会的彩色光源……光污染直接威胁着环境及人类的健康,使人们视力下降、大脑中枢神经受干扰、生物钟紊乱。同时,影响动植物的正常繁殖、生长。 相似文献
66.
Kamaraj M. Ranjith K. S. Rajeshwari Sivaraj Rajendra Kumar R. T. Hasna Abdul Salam 《环境科学学报(英文版)》2014,26(11):2362-2368
Photocatalytic degradation of Bisphenol A (BPA), a representative endocrine disruptor chemical, was carried out under irradiation of sunlight in the presence of CexZn1-xO nanophotocatalyst. Cerium (Ce) ions were successfully incorporated into the bulk lattice of ZnO by simple co-precipitation process. The CexZn1-xO composite nanostructures exhibited higher photocatalytic efficiency than pure ZnO in the degradation of BPA under sunlight irradiation and nearly complete mineralization of BPA was achieved. The degradation rate was strongly dependent on factors such as the size and structure of catalyst, doping material concentration, BPA concentration, catalyst load, irradiation time and pH levels. This work suggested that the CexZn1-xO assisted photocatalytic degradation is a versatile, economic, environmentally benign and efficient method for BPA removal in the aqueous environment. 相似文献
67.
Ashok Kumar Chakraborty Md Emran Hossain Md Masudur Rhaman K M A Sobahan 《环境科学学报(英文版)》2014,26(2):458-465
A nanoheterojunction composite photocatalyst Bi2O3/TiO2working under visible-light(λ 420 nm) was prepared by combining two semiconductors Bi2O3 and TiO2 varying the Bi2O3/TiO2molar ratio. Maleic acid was employed as an organic binder to unite Bi2O3 and TiO2 nanoparticles. The SEM, TEM, XRD and diffuse reflectance spectra were utilized to characterize the prepared Bi2O3/TiO2nanoheterojunction. The nanocomposite exhibited unusual high photocatalytic activity in decomposing 2-propanol in gas phase and phenol in aqueous phase and, evolution of CO2 under visible light irradiation while the end members exhibited low photocatalytic activity. The composite was optimized to 5 mol% Bi2O3/TiO2. The remarkable high photocatalytic efficiency originates from the unique relative energy band position of Bi2O3 and TiO2 as well as the absorption of visible light by Bi2O3. 相似文献
68.
Zhiqiao He Liyong Zhan Fangyue Hong Shuang Song Zhengying Lin Jianmeng Chen Mantong Jin 《环境科学学报(英文版)》2011,23(1):166-170
I-doped titanium dioxide nanospheres (I-TNSs) were synthesized via a two-step hydrothermal synthesis route, their potential for the
e cient utilization of visible light was evaluated. The prepared anatase-phase I-TNSs had a bimodal porous size distribution with a
Brunauer-Emmett-Teller surface area of 76 m2/g, a crystallite size of approximately 14 nm calculated from X-ray di raction data, and
a remarkable absorption in the visible light region at wavelengths > 400 nm. The photocatalytic activity of the samples was evaluated
by decoloration of Methyl Orange in aqueous solution under visible light irradiation in comparison to the iodine-doped TiO2 (I-TiO2).
The I-TNSs showed higher photocatalytic e ciency compared with I-TiO2 after irradiation for 180 min even though the latter had a
much greater surface area (115 m2/g). It was concluded that the surface area was not the predominant factor determining photocatalytic
activity, and that the good crystallization and bimodal porous nanosphere structure were favourable for photocatalysis. 相似文献
69.
70.
视频监控作为安防行业的主要业务,已经历经了多年的发展与变迁。视频监控技术在人员搜索和车辆管控及违章取证等方面,为公安部门提供了大量的帮助与支持,目前应用场景已十分广泛,包括平安城市、雪亮工程、酒店、车站、广场、住宅小区等等。目前视频监控成像依然受限于环境光线,在白天可以提供清晰、色彩还原度高的影像,然而在低光照的夜间环境下成像质量大幅下降,而夜间由于环境光线不足或者全无光。 相似文献