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991.
Guang-hui Cai 《Journal of mathematical chemistry》2008,43(1):375-385
Consider the partly linear regression model Y = xβ + g(t) + e where the explanatory x is erroneously measured, and both t and the response Y are measured exactly, the random error e is ρ−-mixing. Let be a surrogate variable observed instead of the true x in the primary survey data. Assume that in addition to the primary data set containing N observations of , which is ρ−-mixing data sets, an independent validation data containing n observations of is available. The exact observations on x may be obtained by some expensive or diffcult procedures for only a small subset of subjects enrolled in the study. In this
paper, inspired by Berberan-Santos et al. [J. Math. Chem. 37 (2005)101], a semiparametric method with the primary data is
employed to obtain the estimators of β and g(·) based on the least squares criterion with the help of validata. The proposed estimators are proved to be strongly consistent.
相似文献
992.
The great performance of a fibrous bed bioreactor (FBB) is mainly dependent on the cell adhesion and immobilization into the
fibrous matrix. Therefore, understanding the mechanism and factors controling cell adhesion in the fibrous matrix is necessary
to optimize the FBB setup and further improve the fermentability. The adhesion behavior of a strain of Clostridium tyrobutyricum isolated from an FBB was studied, which was proven to be affected by the different environmental conditions, such as growth
phase of cells, pH, ionic strength, ionic species, and composition of media. Our results also suggested that electrostatic
interactions played an important role on bacteria adhesion into the fibrous matrix. This study demonstrated that the compositions
of fermentation broth would have a significant effect on cell adhesion. Consequently, a two-stage glucose supply control strategy
was developed to improve the performance of FBB with higher viable cell density in the operation of the FBB setup. 相似文献
993.
994.
Xiao Wen Hu Zhi Min Zheng Cai Hong Xu 《中国化学快报》2007,18(11):1351-1352
Three new 1,3-bis(phenylethynyl)disilazanes were synthesized from the reaction of 1,3-dichlorodisilazanes with (phenylethy- nyl)lithium,and characterized by infrared (IR) spectra,nuclear magnetic resonance (NMR) and mass spectrometry (MS). 相似文献
995.
A HPLC method was developed and applied to analyze aristolochic acids (AA-I and AA-II) in Chinese medicinal herbs. The herb samples were extracted by using ultrasonication with the extraction efficiency of better than 82%. Extracts were then filtered and injected onto a C18 column eluting under a gradient program using methanol and water-containing 0.5% acetic acid. The method with the detection limits of 1.33 ng for AA-I and 7.29 ng for AA-II per injection was successfully applied for the analysis of traditional Chinese medicine (TCM) and related products and differentiation of Chinese medicinal herbs that have previously been misused and caused toxicological effects. The developed protocol provided an example that analysis of selected component markers could serve for health security and quality control of TCM consumption. 相似文献
996.
(η~5-C_5H_5)_4Mo_4Fe_2(μ_3-S)_5(CO)_5 have been prepared from (η~5-C_5H_5)_2Mo_2(CO)_6 and Fe_8S_2(CO)_9 under toluene reflux for 14.5 hrs.The crystal and molecular structures of (η~5-C_5H_5)_4Mo_4Fe_2(μ_3-S)_5(CO)_5 were studied by X-ray structure analysis. The Crystallographic data are as follows: monoclinic, space group P2_1/n, unit cell: a=1.0589(4), b=1.7260(4), c=1.8963(4) nm, β=101.44(2)°, V=3.3967 nm, D_c=2.06 gcm~(-3) for Z=4, X-ray data were obtained over the range of 2°<2θ<50° via the ω-2θ scan mode with MoKα radiation on an Enraf-Nonius CAD4 diffractometer. The structure was solved by direct method (MULTAN) and refined by full matrix least-squares techniques for 3993 reflections with I>2σ(I), The final R=0.081. Figure 1 illustrates the configuration of the molecule (η~5-C_5H_5)_4Mo_4Fe_2(μ_3-S)_5(CO)_5, composing of a cubane-like (FeMo_3S_4) core and a trigonal pyramid (MoFe_2S) core, which linked by sharing Fe(1) atom. 相似文献
997.
Qintong Huang Ningyue Chen Lichen Liu Karen S. Arias Sara Iborra Xianfeng Yi Chao Ma Weichi Liang Anmin Zheng Chuanqi Zhang Jibo Hu Zilin Cai Yi Liu Jiuxing Jiang Avelino Corma 《Chemical science》2020,11(44):12221
Aluminosilicate boggsite (Si/Al-BOG) has been hydrothermally synthesized without adding organic structure-directing agents (OSDAs) in the synthesis gel using the borosilicogermanium ITQ-47 (Si/B-ITQ-47) zeolite as seeds. The introduction of the costly and environmentally less benign phosphazene organic structure-directing agent is not required to grow the zeolite. Physicochemical characterization experiments show that Si/Al-BOG has good crystallinity, high surface area, tetrahedral Al3+ species, and acid sites. In order to test the catalytic performance of the zeolite, the synthesis of l,l-lactide from l-lactic acid was performed. Si/Al-BOG exhibits 88.2% conversion of l-lactic acid and 83.8% l,l-lactide selectivity, which are better than those of other zeolites studied up to now.Aluminosilicate boggsite (Si/Al-BOG) has been hydrothermally synthesized without adding organic structure-directing agents (OSDAs) in the synthesis gel using the borosilicogermanium ITQ-47 (Si/B-ITQ-47) zeolite as seeds. 相似文献
998.
Cheng-Zhu Wu Xing Fu Cai Seong Su Hong Eun-Kyoung Seo Ji-Xing Nan Jung Joon Lee 《Tetrahedron letters》2007,48(50):8861-8864
Two novel dimeric meroterpenoids, bisbakuchiols A and B, along with (S)-bakuchiol were isolated from the seeds of Psoralea corylifolia L. (Fabaceae). Bisbakuchiols A and B contain an unprecedented dimeric meroterpenoid skeleton in which two meroterpenes are linked through a dioxane bridge. All compounds were evaluated for their potential to inhibit hypoxia-inducible factor-1 (HIF-1) activation induced by hypoxia in a HIF-1-mediated reporter gene assay in AGS human gastric cancer cells. (S)-Bakuchiol inhibited hypoxic activation of HIF-1 with an IC50 value of 6.1 μM. 相似文献
999.
Höfer I Crüsemann M Radzom M Geers B Flachshaar D Cai X Zeeck A Piel J 《Chemistry & biology》2011,18(3):381-391
Hormaomycin produced by Streptomyces griseoflavus is a structurally highly modified depsipeptide that contains several unique building blocks with cyclopropyl, nitro, and chlorine moieties. Within the genus Streptomyces, it acts as a bacterial hormone that induces morphological differentiation and the production of bioactive secondary metabolites. In addition, hormaomycin is an extremely potent narrow-spectrum antibiotic. In this study, we shed light on hormaomycin biosynthesis by a combination of feeding studies, isolation of the biosynthetic nonribosomal peptide synthetase (NRPS) gene cluster, and in vivo and in vitro functional analysis of enzymes. In addition, several nonnatural hormaomycin congeners were generated by feeding-induced metabolic rerouting. The NRPS contains numerous highly repetitive regions that suggest an evolutionary scenario for this unusual bacterial hormone, providing new opportunities for evolution-inspired metabolic engineering of novel nonribosomal peptides. 相似文献
1000.
结合三维静电势参数研究二取代苯的定量结构-疏水性关系 总被引:1,自引:0,他引:1
对含有常见取代基的92个二取代苯化合物进行了结构优化和静电势及其导出参数的计算,运用多元线性回归方法对化合物的疏水常数与分子的结构参数进行了关联.结果表明,分子表面负静电势的加和ΣV-S、分子空间内最负的静电势Vmin、表面最大静电势Vs,max以及分子体积V、极性表面积APS和分子的偶极密度μ/V这六个参数,可以很好地用于表达这些化合物疏水性与分子结构间的定量关系,而不用具体考虑分子中极性基团间的相互作用.用建立起来的QSPR(quantitative structure-property relationship)关系式对111个类似化合物的疏水性进行了预测,获得了满意的结果. 相似文献