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121.
122.
基于辐射的温度测量方程的构造研究 总被引:5,自引:1,他引:4
基于辐射的温度测量方程,以采用选择不同的波长,不同的温度和不同的谱色(滤色片子以技术实现)等方法进行构造,依据这些方法获得的测量数据彼此之间线性无关,从而可以将被测物体发射率函数的具体形式和温度予以确定。 相似文献
123.
EVIDENCE FOR INVOLVEMENT OF PHYTOCHROME REGULATION IN MALE STERILITY OF A MUTANT OF Oryza sativa L. 总被引:1,自引:0,他引:1
Abstract— A rice mutant ( Oryza sativa L. Nongken 58S) "Hubei photoperiod-sensitive genie male-sterile rice" ( ms mutant) has been found to be male sterile under long day cycles (LD) and fertile in short day cycles (SD). After formation of the secondary rachis-branch primodia the mutant plants under SD were interrupted in the middle of the long night phase (night break) for 10 days with 5 min pulses of red light (R) or far-red light (FR). Rates of normal pollen and seed setting of the mutant treated by R or R → FR → R declined significantly, while the rates after FR or R → FR treatments were similar to those under SD alone. The result of these induction reversion experiments is consistent with the operational criteria for the involvement of photochrome. Wild-type rice ( O. sativa L. Nongken 58) under the same treatment showed no change in fertility. Experiments on the effect of different dark intervals (20 s to 15 min) between R and FR on male sterility of the ms mutant showed that the longer the dark interval, the greater the escape of R induction from FR reversibility. Treatment with SD or LD after formation of pollen mother cells had no influence on fertility of the ms mutant plants treated previously with R or FR night breaks. 相似文献
124.
A constructive approach to the determination of an approximate solution of a boundary value problem with nonlinear boundary conditions g[z (0), z (T)]=0 is proposed. Existence of the exact solution is proved, and error estimates for the constructed approximate solution are provided.Translated from Ukrainskii Matematicheskii Zhurnal, Vol. 42, No. 7, pp. 951–957, July, 1990. 相似文献
125.
126.
Ling Tian TANG Yi WANG Xin Qi LIU Shao Wen HU Tai Wei CHU Xiang Yun WANG* College of Chemistry Molecular Engineering Peking University Beijing 《中国化学快报》2005,16(3):345-348
Benzimidazole compounds have attracted a renewed interest recently owing to theirpotential applications in high-performance composite materials, electronic chemicals,photosensitive materials, and their special potentials in biological and/or medicinalapplication1,2. Typically, aromatic compounds with near planar structures and contain-ing hydrogen-donor groups or groups, which are capable of being protonated, havespecial interactions with DNA via intercalation, hydrogen-bonding, and so on3.Me… 相似文献
127.
在深海远程正交频分复用(Orthogonal Frequency Division Multiplexing,OFDM)水声通信中,信道时延较长,导致信道频率选择性衰落严重,传统的压缩感知信道估计算法性能大幅下降。为此,本文利用深海远程信道在一定时间内具有相关性并呈较稳定簇状分布的特点,在分布式压缩感知信道估计中引入簇区域信息,进行簇约束的多数据块联合稀疏信道估计,提出一种簇约束的分布式压缩感知信道估计方法,并在深海开展了定点远程水声通信实验进行验证,实验结果表明,与传统的分布式压缩感知信道估计算法相比,本方法的能够降低50%左右的误码率。 相似文献
128.
Numerical simulation: The dynamic behavior of reinforced concrete plates under normal impact 总被引:3,自引:0,他引:3
This investigation deals with the use of the finite element method on the reinforced concrete structural dynamic response and failure behavior when subjected to the projectile impacts of different velocities, using the test conducted in [S.J. Hanchak, M.J. Forrestal, E.R. Young, J.Q. Ehrgott, Perforation of concrete slabs with 48 MPa (7 ksi) and 140 MPa (20 ksi) unconfined compressive strengths, Int. J. Impact Eng. 12 (1992) 1–7]. The Johnson–Holmquist concrete material constitutive law model is employed to simulate the large strains, high strain states and high pressures to which the concrete is subjected. The projectile impact velocity ranges from 381 m/s to 1058 m/s. Numerical simulations demonstrate that the Johnson–Holmquist concrete material constitutive model can describe the different failure modes without any predefined defects in the element mesh, and normally obtain good agreement between the numerical simulations and test results. 相似文献
129.
Dr. Xin Fang Ying Tong Di Yu Zhang Dr. Zhi Ping Xu Prof. Yang Lu Qian Qian Chen Prof. Qi Tai Zheng Prof. Dr. Xiao Jiang Hao 《Angewandte Chemie (International ed. in English)》2015,54(19):5592-5595
Perforalactone A ( 1 ), a new 20S quassinoid with a unique cagelike 2,4‐dioxaadamantane ring system and a migrated side chain, was isolated from the plant Harrisonia perforata together with two biosynthetically related new quassinoids. The structures of these natural products were elucidated by NMR spectroscopy, X‐ray diffraction analysis, computational modeling, and the CD excitation chirality method. The compounds exhibited notable biological properties, including insecticidal activity against Aphis medicaginis Koch and antagonist activity at the nicotinic acetylcholine receptor of Drosophila melanogaster. The structural features of these compounds may be related to their promising biological characteristics. Their biosynthesis and an alternative origin of quassinoid‐type natural products are also discussed. 相似文献
130.
Dale McMorrow Michon Irons Wyche Pi Tai Chou Michael Kasha 《Photochemistry and photobiology》2015,91(3):576-585
Trace quantities of hydrogen‐bonding impurities in otherwise highly purified and dried glassy hydrocarbon matrices at 77 K can modify the relative triplet state energy levels, and hence the photophysical properties of two aromatic ketones, xanthone and chromone, to the extent that the intrinsic spectroscopic properties are obscured. The intrinsic spectroscopic properties of each are revealed in multicrystalline n‐alkane Shpol'skii matrices, and also can be observed in rigorously purified and dried hydrocarbon glasses at 77 K. The extreme sensitivity to stoichiometric, and even substoichiometric quantities of hydrogen‐bonding impurities arises from the near‐degeneracy of the two lowest‐lying triplet states, and the sensitive nature of the n→π* blueshift phenomena to specific hydrogen‐bonding interactions. 相似文献