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二聚体水分子的10种稳定结构的MP2方法研究 被引量:2
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作者 杨忠志 于春阳 《辽宁师范大学学报(自然科学版)》 CAS 北大核心 2008年第1期67-69,共3页
二聚体水体系是液态水分子体系中氢键存在的原型,目前对它的研究大多是关于其最稳定构型,而忽略了势能面上的其它稳定结构.本文在MP2/aug-cc-pVDZ理论水平下对二聚体水分子进行均衡(CP)校正梯度优化,计算得到二聚体水分子势能面上的10... 二聚体水体系是液态水分子体系中氢键存在的原型,目前对它的研究大多是关于其最稳定构型,而忽略了势能面上的其它稳定结构.本文在MP2/aug-cc-pVDZ理论水平下对二聚体水分子进行均衡(CP)校正梯度优化,计算得到二聚体水分子势能面上的10种稳定构型,并进一步计算得到了它们的相互作用能和偶极矩等重要性质.结果表明,具有Cs对称性的构型1最稳定,其相互作用能ΔE为-4.47 kcal/mol;而具有C2h对称性的构型8最不稳定,其相互作用能ΔE仅为-1.15 kcal/mol. 展开更多
关键词 二聚体水 MP2方法 均衡校正梯度优化
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Cyclobutane Pyrimidine Dimer Accumulation in Relation to UV-B Sensitivity in Rice Cultivars 被引量:1
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作者 李韶山 王艳 +2 位作者 王小菁 宾金华 刘颂豪 《Acta Botanica Sinica》 CSCD 2000年第6期576-581,共6页
Five rice ( Oryza sativa L.) cultivars, widely planted in South China, were grown in greenhouse with or without supplemental UV_B radiation at level of 13.6 kJ·m -2 ·d -1 . After 15 day_UV_B treat... Five rice ( Oryza sativa L.) cultivars, widely planted in South China, were grown in greenhouse with or without supplemental UV_B radiation at level of 13.6 kJ·m -2 ·d -1 . After 15 day_UV_B treatment, significant intraspecific differences were observed in plant height, photosynthetic rate and total biomass. Based on the total biomass accumulation, cultivar “Tesanai” was found to be the most sensitive, and cultivar “Luhuangzhan” was the most tolerant species to UV_B radiation. UV_B induced cyclobutane pyrimidine dimer (CPD) in rice DNA were quantified by ELISA with specific monoclonal antibody. CPD accumulations in DNA extracted from 5 rice cultivars were remarkably increased by UV_B radiation, and it was confirmed that there was a strong positive correlation between CPD accumulation and the inhibition of total biomass. Photorepair was proved to be the predominant mode of CPD repair in UV_B irradiated rice. Light_dependent removal of CPD was very fast as compared with dark repair. Different levels of CPD accumulation among rice cultivars were related with different capacity of CPD photorepair. Capacity of light_dependent CPD removal may play an important role in UV_B resistance of rice. 展开更多
关键词 cyclobutane pyrimidine dimer (CPD) DNA repair RICE UV_B sensitivity
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The relationship between level of plasma D-dimer and survival time in metastatic gastric cancer patients 被引量:3
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作者 Xiaodong Jiao Jianxin Qian Guanzhen Yu Rui Li Zhan Wang Jin Wang Xiaoqiang Gu Jiejun Wang 《The Chinese-German Journal of Clinical Oncology》 CAS 2011年第8期455-458,共4页
Objective:The principal purpose of this study was to determine the relationship between level of plasma D-dimer and survival time in metastatic gastric cancer patients.Methods:We retrospectively collected the data of ... Objective:The principal purpose of this study was to determine the relationship between level of plasma D-dimer and survival time in metastatic gastric cancer patients.Methods:We retrospectively collected the data of plasma D-dimer in metastatic gastric cancer patients admitted in our Department (Department of Oncology,The Affiliated Changzheng Hospital,The Second Military Medical University,Shanghai,China) from October 2006 to October 2008 and analyzed the relationship between level of plasma D-dimer and survival time along with other clinicopathologic parameters.Results:A total of 82 patients were studied in our research,52 were males and 30 females,and the mean age was 57 years.The 48 cases had a normal plasma D-dimer level (<300μg/L) and 34 had a high plasma D-dimer level (≥300μg/L).In the normal and high plasma D-dimer level groups,the mean survival times were 10.9 (95% CI:9.8-12.2) months and 6.8(95% CI:4.4-7.6) months respectively,and the difference was statistically significant.Conclusion:Metastatic gastric cancer patients with high plasma D-dimer level had significantly shorter survival time than those with normal plasma D-dimer level.Level of plasma D-dimer can be referred as a potential predictor in metastatic gastric cancer patients. 展开更多
关键词 metastatic gastric cancer D-DIMER survival time
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Hydrothermal Synthesis and Crystal Structure of [H_4As_8V_(14)O_(42)(H_2O)]·6H_2O
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作者 崔小兵 徐吉庆 +3 位作者 李光华 施展 丁红 杨国昱 《Chinese Journal of Structural Chemistry》 SCIE CAS CSCD 北大核心 2004年第10期1138-1142,共5页
The title compound [H4As8V14O42(H2O)]6H2O 1 has been synthesized and characterized by elemental analysis, IR, and single-crystal X-ray diffraction analysis. It crystallizes in trigonal, space group R3c with a = b = 36... The title compound [H4As8V14O42(H2O)]6H2O 1 has been synthesized and characterized by elemental analysis, IR, and single-crystal X-ray diffraction analysis. It crystallizes in trigonal, space group R3c with a = b = 36.447(6), c = 21.485(5) ? V = 24717(8) 3, Z = 18, Mr = 2114.66, Dc = 2.557g/cm3, F(000) = 17928, m = 7.149 mm-1, R = 0.0792 and wR = 0.1265. The [H4As8V14O42- (H2O)] cluster consists of fourteen VO5 square pyramids linked by four As2O5 handle-like units. 展开更多
关键词 hydrothermal synthesis POLYOXOMETALATE arsenic-vanadium cluster hydrogen bond crystal structure
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Are Polymers Toxic? Case Study: Environmental Impact of a Biopolymer
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作者 Giovanna Mercado Martha Dominguez +1 位作者 Israel Herrera Rosa Maria Melgoza 《Journal of Environmental Science and Engineering(B)》 2017年第3期121-126,共6页
In this paper, the analysis of the environmental impacts of a biopolymer based on starch is presented. These impacts were calculated from a cradle to gate LCA (Life Cycle Assessment), based on UNEEN ISO 14040:2006 ... In this paper, the analysis of the environmental impacts of a biopolymer based on starch is presented. These impacts were calculated from a cradle to gate LCA (Life Cycle Assessment), based on UNEEN ISO 14040:2006 and UNEEN ISO 14044, using as functional unit 1 kg of produced biomaterial. The impact categories analyzed were global wanning, ozone depletion, acidification and eutrophication. The results indicate that the electricity causes the highest impacts in the global warming and ozone depletion categories, but compared to synthetic polymers, the emissions are low. Finally, in the case of eutrophication, the impacts are similar to other biopolymers but higher in comparison with petroleum-based polymers like HDPE (High Density Polyethylene), LDPE (Low Density Polyethylene), PP (Polypropylene), PS (Polystyrene) and PET (Polyethylene Terephthalate). 展开更多
关键词 Polymer BIOPOLYMER LCA environmental impacts.
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A hybrid carboxylate-water decamer with a discrete octameric water moiety self-assembled in a 2D copper(Ⅱ) coordination polymer 被引量:3
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作者 LUO GengGeng WU DongLiang +4 位作者 LIU Li LI DongXu ZHAO QingHua XIAO ZiJing DAI JingCao 《Science China Chemistry》 SCIE EI CAS 2012年第7期1213-1219,共7页
An octameric water moiety which consists of a chairlike water hexamer and two pendent water molecules in the 1,4-diaxial positions and shows a similar structure to the hydrocarbon (lr,4r)-1,4-dimethylcyclohexane, is... An octameric water moiety which consists of a chairlike water hexamer and two pendent water molecules in the 1,4-diaxial positions and shows a similar structure to the hydrocarbon (lr,4r)-1,4-dimethylcyclohexane, is unambiguously trapped in a 2D Cu(II) mixed-ligand coordination polymer, {[Cu2(bpp)2(HzO)2(bpda)2]'6H2O}n (1) (bpp = 1,3-bis(4-pyridyl)propane and H2bpda = 2,2'-biphenyldicarboxylic acid). The water octamer can be extended into a hybrid carboxylate-water decamer when carboxylic oxygen atoms from bpda2- are involved. Interestingly, the present hybrid decamer bears a similar structural topology to a butterfly (H2O)10 cluster. The reversible dehydration/hydration of 1 is determined by X-ray powder diffraction studies. 展开更多
关键词 water octamer hybrid carboxylate-water decamer dehydration-rehydration helical chains
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