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991.
992.
SynthesisofPoly(styrene┐co┐divinylbenzene)┐supportedDichloroCyanuricAcidZHONGJing-fang*,LIChen-xi,HEBing-linandWUZhi-zhong(St... 相似文献
993.
一种裂纹梁振动响应分析的近似方法 总被引:7,自引:0,他引:7
本文以线弹簧模型为基础提出了一种近似分析裂纹梁振动响应的方法.把该方法同Euler-Bernoulli梁理论、模态分析方法以及断裂力学原理等结合起来运用,导出裂纹梁振动的特征方程.作为应用实例,本文考核了简支裂纹梁和悬臂裂纹梁的固有频率响应.结果表明,本文所获得的解与现有文献中的解或实验结果取得很好的一致. 相似文献
994.
Wei-Qun Yang Wei Tang Xiao-Jun Huang Jian-Guo Song Yue-Yue Li Yu Xiong Chun-Lin Fan Zhen-Long Wu Ying Wang Wen-Cai Ye 《Molecules (Basel, Switzerland)》2021,26(19)
A phytochemical investigation on the roots of medicinal plant Eurycoma longifolia resulted in the isolation of 10 new highly oxygenated C20 quassinoids longifolactones G‒P (1–10), along with four known ones (11–14). Their chemical structures and absolute configurations were unambiguously elucidated on the basis of comprehensive spectroscopic analysis and X-ray crystallographic data. Notably, compound 1 is a rare pentacyclic C20 quassinoid featuring a densely functionalized 2,5-dioxatricyclo[5.2.2.04,8]undecane core. Compound 4 represents the first example of quassinoids containing a 14,15-epoxy functionality, and 7 features an unusual α-oriented hydroxyl group at C-14. All isolated compounds were evaluated for their anti-proliferation activities on human leukemia cells. Among the isolates, compounds 5, 12, 13, and 14 potently inhibited the in vitro proliferation of K562 and HL-60 cells with IC50 values ranging from 2.90 to 8.20 μM. 相似文献
995.
Lúcio Ricardo Leite Diniz Hatem A. Elshabrawy Marilia Trindade de Santana Souza Allana Brunna Sucupira Duarte Sabarno Datta Damio Pergentino de Sousa 《Molecules (Basel, Switzerland)》2021,26(19)
Data obtained from several intensive care units around the world have provided substantial evidence of the strong association between impairment of the renal function and in-hospital deaths of critically ill COVID-19 patients, especially those with comorbidities and requiring renal replacement therapy (RRT). Acute kidney injury (AKI) is a common renal disorder of various etiologies characterized by a sudden and sustained decrease of renal function. Studies have shown that 5–46% of COVID-19 patients develop AKI during hospital stay, and the mortality of those patients may reach up to 100% depending on various factors, such as organ failures and RRT requirement. Catechins are natural products that have multiple pharmacological activities, including anti-coronavirus and reno-protective activities against kidney injury induced by nephrotoxic agents, obstructive nephropathies and AKI accompanying metabolic and cardiovascular disorders. Therefore, in this review, we discuss the anti-SARS-CoV-2 and reno-protective effects of catechins from a mechanistic perspective. We believe that catechins may serve as promising therapeutics in COVID-19-associated AKI due to their well-recognized anti-SARS-CoV-2, and antioxidant and anti-inflammatory properties that mediate their reno-protective activities. 相似文献
996.
自然复合材料的强韧化机理和仿生复合材料的研究 总被引:12,自引:0,他引:12
本文评述了一个新的研究方向─—自然复合材料强韧化的细观机理及其仿生复合材料的研究。着重考察了木、人骨、贝壳珍珠层、昆虫外骨骼及翅等自然复合材料的研究现状,基于这些研究,部分仿生材料已被设计和制造出来并达到商用程度.复合材料在细观层次的仿生,是将对复合材料及其结构设计产生潜在冲击的重要发展方向. 相似文献
997.
张福范 《应用数学和力学(英文版)》1986,7(10):937-945
This paper is to solve the interlaminar stresses of adhesive lap joint by the energy method without considering the adhesive layer. The joint is made of two identical narrow plates. Two cases are discussed: one is for the isotropic material and the other is for orthotropic material. Because of the different materials forming the joint, the length of distribution and the magnitude of the interlaminar, stresses for the two cases will be very different.Projects supported by the Science Fund of Chines Academy of Sciences (1986–1988). 相似文献
998.
999.
R. Khattree D. P. Schmidt I. E. Schochetman 《Journal of Optimization Theory and Applications》1999,103(2):359-384
We consider an infinite-dimensional isotonic regression problem which is an extension of the suitably revised classical isotonic regression problem. Given p-summable data, for p finite and at least one, there exists an optimal estimator to our problem. For p greater than one, this estimator is unique and is the limit in the p-norm of the sequence of unique estimators in canonical finite-dimensional truncations of our problem. However, for p equal to one, our problem, as well as the finite-dimensional truncations, admit multiple optimal estimators in general. In this case, the sequence of optimal estimator sets to the truncations converges to the optimal estimator set of the infinite problem in the sense of Kuratowski. Moreover, the selection of natural best optimal estimators to the truncations converges in the 1-norm to an optimal estimator of the infinite problem. 相似文献
1000.
S. Lakshmi K. Subramanian T. Steiner B. Varghese 《Journal of chemical crystallography》1999,29(10):1141-1143
The X-ray crystal structure of the triterpenoid piscidinol-C from the leaves of Walsura piscidia is determined. The compound, which is an apotirucallane derivative, crystallizes in the orthorhombic space group C2221 with a = 18.985(4), b = 13.092(5), c = 24.690(7) Å, and D
calc = 1.209 g cm–1 for Z = 8. 相似文献