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401.
ZHU Jun ZHANG Yun CHEN Hao CHE Yun-Xia ZHENG Ji-Min ② 《结构化学》2006,25(8):1011-1013
1 INTRODUCTION Nonlinear optics (NLO) is at the forefront of cur- rent researches because of its importance in provi- ding the key functions of frequency shifting, optical modulation, optical switching, optical logic and op- tical memory for the emerging … 相似文献
402.
高聚物微流控芯片具有制备简单、成本低、可批量生产等突出优点而有望成为一次性器件,近年来在国内外引起了同行们的兴趣.但是,高聚物表面的憎水性、对有机分子的强吸附性、电渗流的不稳定性等又成为高聚物芯片在微流控分析领域得以广泛应用的障碍.表面改性是改善高聚物芯片分析特性的有效途径. 相似文献
403.
An efficient, amine- and phosphine-free palladium(II)-catalyzed homocoupling of terminal alkynes has been developed. In the presence of PdCl2, CuI, Me3NO, and NaOAc, homocoupling of various terminal alkynes underwent smoothly to afford the corresponding diynes in moderate to high yields without any phosphine ligands. In contrast, the presence of a phosphine ligand (PPh3) disfavored this palladium-catalyzed homocoupling procedure. Bases, solvents, and CuI have fundamental influence on the palladium-catalyzed homocoupling of terminal alkynes. 相似文献
404.
季铵盐Gemini表面活性剂C12-s-C12·2Br(s=2,3,4,6)与丙醇、丁醇、戊醇、己醇混合水溶液的In(cmc)随温度升高而逐渐增大.计算所得热力学数据表明,C12-s-C12·2Br与醇混合胶团化过程服从熵驱动机理,也出现了焓/熵补偿现象.随着温度上升,熵驱动力增大,在指定温度时,醇分子烷烃链上碳原子数n增大使△Gm0值减小,胶团结构更加稳定;而增加s使值增大,胶团稳定性下降. 相似文献
405.
Lee MS Yang DY Cheng CL Liang YJ Yang LL Cheng FC 《Journal of chromatography. A》2003,985(1-2):387-394
The aim of this study was to evaluate dynamic changes in energy-related metabolites in the cortex of gerbils subjected to focal cerebral ischemia after pretreatment with Ginkgo biloba extract. Focal cerebral ischemia was induced by occlusion of the right common carotid artery and the right middle cerebral artery for 60 min in anesthetized gerbils. A microdialysis probe was inserted into the cortex to monitor extracellular lactate. pyruvate and ascorbate during ischemia and reperfusion. The present study demonstrated a dynamic decrease in pyruvate (25% of baseline) and increases in lactate (160% of baseline) and asorbate (300% of baseline) and a 5-fold increase in the lactate:pyruvate (L:P) ratio during cerebral ischemia in the control group. However. pyruvate levels were preserved and ascorbate levels were enhanced with a chronic pretreatment of Ginkgo biloba extract for 8 days (i.p., 100 mg kg(-1) day(-1)). Preservation of pyruvate and enhancement of ascorbate observed in this study may be associated with the neuroprotective effects of Ginkgo biloba extract. 相似文献
406.
Three new hetero‐bischelated rhodium (III) complexes of cis‐[Rh(PA)(L)Cl2]Cl (where PA = phenylpyridin‐2‐ylmethylene‐amine; L = 2,2′‐bipyridine, 2,2′‐dipyridylamine and 1,10‐phenanthroline) have been successfully prepared and characterized. Each complex shows high intensity bands in the UV region, and these are assigned to spin‐allowed π‐π* transitions. The medium‐intensity absorption band profile in the lower energy region can be explained by convolution of spin‐allowed CT and d‐d* transitions. The emission spectra at low temperature (77 K) of these complexes in EtOH/MeOH (4:1 v/v) are virtually identical. They all exhibit a broad, symmetric, and structureless red emission with a microsecond lifetime and hence are assigned as the d‐d* phosphorescence. 相似文献
407.
乙酰化淀粉/DL-丙交酯接枝共聚物的合成及降解性能研究 总被引:7,自引:0,他引:7
用醋酸乙烯酯和玉米淀粉反应制备出了不同取代度乙酰化淀粉,再用乙酰化淀粉同DL-丙交酯接枝共聚合成乙酰化淀粉/DL-丙交酯接枝共聚物。研究了原料配比,淀粉取代度对接枝反应单体转化率(C%),接枝率(G%)接枝效率(GE%)和接枝支链数均分子量(Mn)的影响,结果表明在给定的试验条件下接枝共聚反应的C%,G%,GE%和Mn可分别达到40%,225%,80%和1.4万。接枝共聚物在磷酸缓冲溶液和户外土壤掩埋降解实验表明,在160天内样品失重率分别为71%和60%,表明合成的乙酰化淀粉/DL-丙交酯接枝共聚物具有很好的降解性能。 相似文献
408.
In this study, local least squares (LLS) and principal component analysis (PCA) were applied to deal with the disturbances in a data set of chromatographic fingerprints after necessary data transformations. It has been demonstrated that PCA with standard normal variate (SNV) transformation of data led to meaningful classification of 33 different Erigeron breviscapus herbal samples. The result was also corroborated by variance squares discriminant method. The quality of herbal objects was further evaluated, and the causes of this fact have been explained from a chemical point of view. At the same time, it implied an idea for qualitative evaluation of the herbal objects with a common class pattern of chromatographic fingerprints. 相似文献
409.
Zhang H Loh KP Sow CH Gu H Su X Huang C Chen ZK 《Langmuir : the ACS journal of surfaces and colloids》2004,20(16):6914-6920
We have synthesized edge-oriented MoS2 nanosheets by the evaporation of a single source precursor based on Mo(IV)-tetrakis(diethylaminodithiocarbomato). The surface chemistry of the MoS2 nanosheets has been studied in order to evaluate the chemical reactivities of the basal planes and edges. By irradiating the MoS2 nanosheet with a scanning infrared laser, micron-scale lithographical structures can be created due to laser-induced oxidation of MoS2 to form nanocrystalline MoO3. Preferential reactivities of the MoS2 basal edges in an electrochemical environment and during vapor phase deposition have been demonstrated. Functionalization of the basal plane with 1-pyrene acetic acid allows the immobilization of DNA and immunoglobins on the MoS2 basal plane. 相似文献
410.
Qing‐Lun Wang Mao Liang Dai‐Zheng Liao Shi‐Ping Yan Zong‐Hui Jiang Peng Cheng 《无机化学与普通化学杂志》2004,630(4):613-616
A unique neodymium(III) complex, {[Nd(BTC)(H2O)4] · H2O}n (BTC = 1, 3, 5‐benzenetricarboxylate), was obtained from the reaction between Nd(ClO4)3 · xH2O and Na3BTC. Coordination bonds, hydrogen bonds, and π‐π stacking form a supramolecular structure with a novel, two‐dimensional framework. The temperature‐dependent magnetic susceptibilities were analyzed by the Curie‐Weiss law; the following values were found C = 1.32, θ = —18.3 K, respectively. 相似文献