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951.
Aquaporins are implicated in a wide variety of plant physiological processes, although the mechanisms involved in their regulation are not fully understood. To gain further insight into the regulatory factors involved in this process, we used a yeast two-hybrid system to screen for potential binding partners to the Arabidopsis tonoplast intrinsic protein (TIP) AtTIP1;1. This was the first protein identified to be associated with high water permeability in vacuolar membranes from Arabidopsis thaliana. Using ... 相似文献
952.
953.
Two letters from William Burnside have recently been found in the Nachlass of Robert Fricke that contain instances of the Burnside Problem prior to its first publication. We present these letters
as a whole to the public for the first time. We draw a picture of these two mathematicians and describe their activities leading
to their correspondence. We thus gain an insight into their respective motivations, reactions, and attitudes, which may sharpen
the current understanding of professional and social interactions of the mathematical community at the turn of the twentieth
century.
Dedicated to Heiko Harborth on the occasion of his seventieth birthday. 相似文献
954.
Sergio Porté Agrin Moeini Irene Reche Naeem Shafqat Udo Oppermann Jaume Farrés Xavier Parés 《Cellular and molecular life sciences : CMLS》2011,68(6):1065-1077
Human ζ-crystallin is a Zn2+-lacking medium-chain dehydrogenase/reductase (MDR) included in the quinone oxidoreductase (QOR) family because of its activity
with quinones. In the present work a novel enzymatic activity was characterized: the double bond α,β-hydrogenation of medium-chain
2-alkenals and 3-alkenones. The enzyme is especially active with lipid peroxidation products such as 4-hydroxyhexenal, and
a role in their detoxification is discussed. This specificity is novel in the QOR family, and it is similar to that described
in the distantly related alkenal/one reductase family. Moreover, we report the X-ray structure of ζ-crystallin, which represents
the first structure solved for a tetrameric Zn2+-lacking MDR, and which allowed the identification of the active-site lining residues. Docking simulations suggest a role
for Tyr53 and Tyr59 in catalysis. The kinetics of Tyr53Phe and Tyr59Phe mutants support the implication of Tyr53 in binding/catalysis
of alkenal/one substrates, while Tyr59 is involved in the recognition of 4-OH-alkenals. 相似文献
955.
The effects of Cl-concentration,temperature,pH,flow velocity,soluble oxygen content of seawater and anodic current on the potential of high purity zinc and Zn-Al-Cd reference electrodes were investigated. The results show that the investigated metal materials are liable to establish stable potential and act as reference electrodes in seawater,diluted seawater and urban tap water. Cl-concentration,temperature,seawater flow velocity and anodic current have an obvious effect on zinc potentials. However,seawate... 相似文献
956.
GaN thin films grown on sapphire were implanted by Eu~3+ with three different fluences (5.0×10~14 , 2.5×10~15 and 5.0×10~15cm~-2 ). The photoluminescence (PL) spectra show that, after annealing, the samples exhibit strong emission at around 622.0 nm under 325 nm laser excitation. The intensity of this emission increases by one order of magnitude after annealing at from 600 ℃ to 900 ℃. Moreover, it increases less than 2 times when the fluence increases from 5×10~14 cm~-2 to 5×10~15 cm~-2 for the sample annealing at 900 ℃. The PL emission peaks around 622 nm of samples annealing at 900 ℃ can be well clarified by Gaussian fitting into 620.2, 622.0 and 625.0 nm, which are due to the Eu~3+ related with defects, Eu~3+ occupied at substitutional positions of Ga, and that located at interstitial sites, respectively. It shows that the different microenvironments and positions of Eu~3+ are responsible for these peaks, and especially the defects introduced by implantation play an important role in the behavior of the PL because they set up an energy transmission bridge from exotic photons to Eu~3+ . 相似文献
957.
To better understand variation of Holocene Chinese mandiblular morphology, a study was conducted on 23 metric traits of Neolithic (n=54), Bronze-Iron Ages (n=184) and modern (n=92) adult male mandibles from northern China. Results indicate that the linear characters of these Chinese mandibles evolved in the past 7000 years. From the Neolithic to Bronze-Iron Ages to present day, the overall size of mandibles decreased. The linear characters of the mandiblular features varied between different time periods. The decrease of thickness and height of the mandibular corpus primarily occurred during the Neolithic to Bronze-Iron Ages. The decrease in main size was during the Bronze-Iron Ages to present day. It is possible that mandibles became thinner before the overall size decreased. Comparisons also indicate that the bottom part of the face may have decreased more greatly in breadth than the upper portion. The decrease in mandible size may be associated with changes in climate and diet, and with changes in the craniums size. 相似文献
958.
要牢固树立安全生产第一的方针,以专业安全知识为内容,用行政奖励、法律、法规为手段,全面增强施工人员的安全意识,不断提高施工人员的自我安全防范能力,明确自己安全生产责、权、利的关系,以达到施工安全效益最佳的目的. 相似文献
959.
蔡圣义 《温州大学学报(自然科学版)》2001,22(6):4-7
对大多数排序问题来说,机器集往往是事先给定的,而且在算法进行过程中,机器集是不变的。Imreh和Noga第一次提出了在排序中考虑机器费用的模型。他们研究了所谓的List Model problem,并给出了竞争比为(1+5的平方根)/2≈1.618的在线算法,同时证明了该模型的任意在线算法的竞争比至少是4/3。本文研究List Model problem的一个半在线情形,我们假设工件的最大加工时间预先知道,我们将给出一个竞争比为19/12≈1.583的半在线算法,同时证明对该问题的这一半在线情形,任意半在线算法的竞争比至少是4/3。这表明部分信息有利于设计更好的算法。 相似文献
960.
通过合理利用锻造毛坯的性能,研究了如何控制环形锻件各向性能的方法,并借助于铝合金锻件的试验,验证了这种方法的可行性。 相似文献