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采用考虑相对论修正的内收缩多参考组态相互作用方法(MRCI+DK),结合Dunning系列的相关一致基,对BrF分子基态的势能曲线进行了计算。并对得到的势能曲线进行拟合,得到BrF分子基态的光谱常数D_e,R_e,ω_e,B_e,α_e和ω_eχ_e,与实验结果比较发现,它们与实验值符合的非常好。通过求解双原子分子核运动径向Schr?dinger方程,找到了转动量子数J=0时BrF分子基态的全部43个振动态。且计算了每一个振动态的振动能级和惯性转动常数;并求出了前20个振动态的经典转折点和离心畸变常数,得到的结果与已有的实验结果较为一致。本文得到的BrF分子基态的光谱常数和分子常数更精确和完整,为进一步的光谱实验研究提供可靠的参考。 相似文献
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Web2.0的研究与应用综述 总被引：26，自引：0，他引：26
近年来，web2．0的产生与发展对图书情报服务、电子政务、企业知识管理与服务等方面产生了深远的影响。本文归纳了web2．0的产生背景、概念及特征；通过文献统计与分析，从Web2．0的理论基础、Web2．0与公共信息服务、web2．0与企业知识管理、Web2．0与网络创业、Web2．0与教育五个方面对Web2．0的理论研究与应用进行了综述，并对Web2．0的发展进行了展望。 相似文献
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测定了石油亚砜萃淋树脂的吸附性能，其饱和吸附容量Ｑ＝９０ｍｇＡｕ／ｇ树脂，金的吸附反应速率常数Ｋ＝１．０２×１０￣（－３）ｓ￣（－１），热焓△Ｈ＝－６．７０ｋＪ／ｍｏｌ，自由能变化△Ｇ￣（２９８）＝－２０．５９ｋＪ／ｍｏｌ，熵变△Ｓ＝４６．６Ｊ／ｍｏｌ·Ｋ．树脂吸附金的反应符合Ｆｒｅｕｎｄｌｉｃｈ等温吸附式．探讨了树胎吸附金的反应机理．用酸性硫脲或亚硫酸钠溶液均能定量洗脱吸附在树脂上的Ａｕ（Ⅲ），树脂可再生使用． 相似文献
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《科技通报》2017,(4)
采用多参考组态相互作用方法(MRCI)结合Dunning等的相关一致基,计算了Li I分子基态的势能曲线和光谱常数(Re,ωeand De)。为获得更准确的结果,计算中还考虑了相对论修正对Li I分子基态的平衡键长、谐振频率和离解能影响。在二阶Douglas-Kroll哈密顿近似下计算得到势能曲线并将其拟合为Murrell-Sorbie解析势能函数形式,并进一步计算得到Li I分子基态的其它光谱常数(ωeχe,αe,Be和D0)。比较发现它们与实验值符合的非常好。通过求解核运动径向Schr?dinger方程,找到了Li I分子基态的全部振动态。还计算了前20个振动态的振动能级、经典转折点、惯性转动常数和离心畸变常数。 相似文献
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用pH电位滴定法测定了铂（Ⅱ）与核苷酸NTP（腺苷5'－三磷酸和尿苷5'－三磷酸）和另一芳环系列配体ArL形成的三元混配配合物Pt(ArL)(NTP)^n-(ArL=Phen,Bpy和Trp;n=2或3）在水溶液中的稳定常数（I＝0．1mol/L,KNO3；25℃）。用△lgKpt比较了二元和三元混配配合物的稳定性差异，认为三元混配配合物稳定性的增加可归因于π－酸－π－碱之间的合作效应和分子内容环配体的堆积作用。 相似文献
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光学活性肌醇及其甲基衍生物的旋光度计算 总被引：1，自引：0，他引：1
根据作者提出的螺旋理论规律~[1]，可以计算光学活性肌醇的族光方向和旋光度大小，肌醇分子内存在的36个二面角螺旋族光度的代数和再乘以常数2．0就是该肌醇的摩尔族光度。 相似文献
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本文系统地研究了甲硝唑在汞电极上的电极过程，证明了该电极过程为一含有吸附作用的不可逆的扩散控制过程，电子转移数为４，不可逆系数ａ＝０．７１４．建立了甲硝唑的单扫示波极谱测定法，在０．２０ｍｏｌ／Ｌ的ＮａＣｌ溶液中，于－０．７１Ｖ（ｖｓＳＣＥ）处的峰高与浓度［（０．０２─８０）ｍｇ／Ｌ］间存在良好的线性关系，检测限为２．４μｇ／Ｌ，ＲＳＤ＝２．０％（ｎ＝８），并考察了人体内常见微量物质对的影响。 相似文献
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猪心线粒体F_1—ATP酶分子组成中约有97个酪氨酸残基,其中相当一部份是暴露的,有约10个左右的色氨酸残基埋藏于分子内部的疏水区。采用不同链长以及不同分支链的甲、乙、正丙、异丙和叔丁五种醇作用于猪心线粒体F_1—ATP酶,观察此酶水解活性变化的同时观察其内源荧光的变化以及用ANS荧光探针观察其疏水区的变化。实验结果指出,当F_1受不同浓度(5％—20％)甲醇作用后其水解活性呈激活状态。这时F_1的内源酪氨酸的荧光增强,这可能是由于F_1分子中酪氨酸残基的暴露有所增加或由于分子二、三、四级的结构有所变化,这后者的构象变化减弱了酪氨酸荧光的猝灭所致。至于对ANS荧光的影响则呈下降现象。当F_1受乙醇、正丙醇、异丙醇或叔丁醇作用后水解活性呈抑制作用时F_1分子中内源色氨酸荧光大为增加。这意味着色氨酸的暴露疏水区的扩大,ANS疏水荧光探针监测的结果与此一致,也是疏水区的扩大。文中对F_1激活与抑制时两种不同构象作了初步介释。 相似文献
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The traditional Bayesian qualitative account of evidential support(TB) takes assertions of the form ‘E evidentially supportsH’ to affirm the existence of a two-place relation ofevidential support between E and H. The analysans given forthis relation is C(H,E) =def Pr(H|E) > Pr(H). Now it is wellknown that when a hypothesis H entails evidence E, not onlyis it the case that C(H,E), but it is also the case that C(H&X,E)for any arbitrary X. There is a widespread feeling that thisis a problematic result for TB. Indeed, there are a number ofcases in which many feel it is false to assert ‘E evidentiallysupports H&X’, despite H entailing E. This is known,by those who share that feeling, as the ‘tacking problem’for Bayesian confirmation theory. After outlining a generalizationof the problem, I argue that the Bayesian response has so farbeen unsatisfactory. I then argue the following: (i) There exists,either instead of, or in addition to, a two-place relation ofconfirmation, a three-place, ‘contrastive’ relationof confirmation, holding between an item of evidence E and twocompeting hypotheses H1 and H2. (ii) The correct analysans ofthe relation is a particular probabilistic inequality, abbreviatedC(H1, H2, E). (iii) Those who take the putative counterexamplesto TB discussed to indeed be counterexamples are interpretingthe relevant utterances as implicitly contrastive, contrastingthe relevant hypothesis H1 with a particular competitor H2.(iv) The probabilistic structure of these cases is such thatC(H1, H2, E). This solves my generalization of the tacking problem.I then conclude with some thoughts about the relationship betweenthe traditional Bayesian account of evidential support and myproposed account of the three-place relation of confirmation.
- 1 The ‘tacking problem’ and the traditional Bayesianresponse
- 2 Contrastive support
- 3 Concluding comments
- 2 Contrastive support
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Vaishali N. Thorat Adinath N. Suryakar Pradeep Nailk Bipin M. Tiwale 《Indian journal of clinical biochemistry : IJCB》2009,24(1):105-107
The aim of this study was to monitor serum nitric oxide levels at various times, intraoperatively and following liver transplantation
in humans. Nitric oxide production was assessed by cadmium reduction method in 15 patients undergoing liver transplantation.
We observed strong correlation between nitric oxide production and allograft rejection. Sustained rise in nitric oxide level
after transplantation might provide an indication of acute allograft rejection. Therefore measurement of nitric oxide, a stable
end product appears to be an excellent marker that can help in the development of strategies intended to improve graft viability
and patient’s survival. 相似文献
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Nitric oxide (NO) a free radical having both cytoprotective as well as tumor promoting agent is formed from l-arginine by converting it to l-citrulline via nitric oxide synthase enzymes. The reaction product of nitric oxide with superoxide generates potent oxidizing
agent, peroxynitrite which is the main mediator of tissue and cellular injury. Peroxynitrite is reactive towards many biomolecules
which includes amino acids, nucleic acid bases; metal containing compounds, etc. NO metabolites may play a key role in mediating
many of the genotoxic/carcinogenic effects as DNA damage, protein or lipid modification, etc. The basic reactions of nitric
oxide can be divided as direct effect of the radical where it alone plays a role in either damaging or protecting the cell
milieu and an indirect effect in which the byproducts of nitric oxide formed by convergence of two independent radical generating
pathways play the role in biological reactions which mainly involve oxidative and nitrosative stress. Nitric oxide is also
capable of directly interacting with mitochondria through inhibition of respiration or by permeability transition. Reaction
of nitric oxide with metal ions include its direct interaction with the metals or with oxo complexes thereby reducing them
to lower valent state. Excessive production of nitric oxide can be studied by inhibiting the synthetic pathway of nitric oxide
using both selective or specific nitric oxide synthase inhibitor or non-selective nitric oxide synthase inhibitor with respect
to isoforms of nitric oxide. 相似文献
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S. D. Walwadkar A. N. Suryakar R. V. Katkam K. M. Kumbar R. D. Ankush 《Indian journal of clinical biochemistry : IJCB》2006,21(2):134-137
Generation of reactive oxygen species is an important factor in the development and maintenance of rheumatoid arthritis (RA)
in humans. This study was undertaken to investigate interplay among oxidants, antioxidants and pathogenesis of Rheumatoid
arthritis. Serum levels of lipid peroxides, nitric oxide, vitamin E and ratio of calcium/phosphorus in RA patients were determined
and compared with normal healthy controls. Significant increases in lipid peroxides (p<0.001) and nitric oxide (p<0.001) levels
were found in patients presenting with RA as compared to controls. Whereas significant decrease in vitamin E (P<0.001) and
calcium/phosphorus ratio (p<0.001) were found in Rheumatoid arthritis patients as compared to controls. Positive correlation
was found between lipid peroxides and nitric oxide as well as between vitamin E and calcium. While lipid peroxides and nitric
oxide were correlated negatively with vitamin E. whereas negative correlation was observed between MDA and Calcium/Phosphorus
ratio in patients with rheumatoid arthritis. Our findings suggest that there is a close association between bone loss and
oxidative threat in patients presenting with Rheumatoid arthritis. 相似文献
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以企业国际化的网络理论研究为基础,通过广州146家国际化企业的问卷调查所获数据,对我国企业外部关系网络与国际化绩效的关系进行实证研究。结果表明企业外部关系网络水平与企业国际化绩效存在显著正相关关系,但关系网络的不同维度对国际化绩效的作用呈现差异,其中关系维度的影响最为显著,其余依次为结构维度和认知维度。我国企业应构建坚实宽广的国际关系网络,建立合作伙伴间的识别机制、信任机制和互动互惠机制等途径提升企业国际关系网络各维度水平以促进企业成功国际化。 相似文献
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目的:鞋与足的匹配度是影响鞋穿着舒适度的最主要因素,为了便于人们日常生活选鞋购鞋,设计实现一种简单易行的方式,以尽可能准确反映人实际穿着的鞋码。方法:利用文献资料法和实验法测量足形态,资料表明计算鞋码时需在足长的基础上加以考虑足宽、性别、鞋型等因素。结果:利用《中华人民共和国国家标准GB/T3293》设计出一种简易鞋码计算公式:S=x+(y-[(x-a)×0.26+b])/0.26注:①x=足长(mm);②y=足宽(mm);③a=鞋中间号;④b=中间号标准鞋宽,b值取决于不同类型的鞋,参考《中华人民共和国国家标准GB/T3293》;⑤s=鞋尺寸(mm)。结论:该公式方法简单易行,计算鞋码结果与实际情况匹配度较高,具有可行性。 相似文献
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Increased oxidative stress is a widely accepted participant in the development and progression of diabetes and its complications.
The present study has been undertaken to evaluate oxidative stress in type 2 diabetes mellitus and effect of vitamin E supplementation
on oxidative stress. In all 120 subjects were enrolled in the present study, 40 subjects are age and sex matched controls.
Test group comprised of clinically diagnosed (n = 80) type 2 diabetic patients. Biochemical parameters like serum MDA, nitric oxide, superoxide dismutase, erythrocyte reduced
glutathione and platelet aggregation were analyzed in control and diabetic group. Test group is further categorized as Group
I (n = 40) diabetics were treated by only hypoglycemic drugs and Group II (n = 40) diabetics were treated by hypoglycemic drugs with vitamin E supplementation. All above biochemical parameters were
again reassessed after 3 months follow-up in both group and its values were compared with its respective baseline levels.
The study shows, reduction of oxidative stress, improvement in antioxidant enzymes and endothelial dysfunction in group II,
those were on treatment of hypoglycemic drugs along with vitamin E supplementation. Hence the present study may conclude that
vitamin E supplementation along with hypoglycemic drugs may be beneficial to type 2 DM patients to minimize vascular complications. 相似文献
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简述堆积型铝土矿采场动态数据的计算方法及管理应用。实践证明,采场动态数据的合理管理对提高矿量计算和品位分析工作效率效果显著,有利于更准确的进行矿产资源的决策规划。 相似文献