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481.
 从理论上推导了材料中空洞分布函数,阐明两种材料,Fe和Ta样品,受不同飞片速度冲击后,其空洞分布的相似性。从文献[5]中又发现,脆性材料的裂纹分布也具有同样的相似性,这说明理论分布函数可能具有普遍性。最后提出了这种性质的广阔应用前景。  相似文献   
482.
塑料镜片材料的发展动向   总被引:1,自引:0,他引:1  
概述光学塑料的基本材料,讨论塑料镜片材料的主要品种及其应用,并着重分析影响塑料镜片材料性能的主要因素及其发展趋势。  相似文献   
483.
多孔硅研究进展   总被引:1,自引:0,他引:1  
综述多孔硅的形成规律,介绍其各种物理、化学特性和形成机制等,并以多孔硅电致光发射器件的研制为主,讨论它的应用技术。  相似文献   
484.
Ablikim M  Bai JZ  Ban Y  Cai X  Chen HF  Chen HS  Chen HX  Chen JC  Chen J  Chen YB  Chu YP  Dai YS  Diao LY  Deng ZY  Dong QF  Du SX  Fang J  Fang SS  Fu CD  Gao CS  Gao YN  Gu SD  Gu YT  Guo YN  Guo ZJ  Harris FA  He KL  He M  Heng YK  Hou J  Hu HM  Hu JH  Hu T  Huang GS  Huang XT  Ji XB  Jiang XS  Jiang XY  Jiao JB  Jin DP  Jin S  Lai YF  Li G  Li HB  Li J  Li RY  Li SM  Li WD  Li WG  Li XL  Li XN  Li XQ  Liang YF  Liao HB  Liu BJ  Liu CX  Liu F  Liu F  Liu HH  Liu HM  Liu J  Liu JB  Liu JP  Liu JL  Liu RG  Liu ZA  Lou YC  Lu F  Lu GR  Lu JG  Luo CL  Ma FC 《Physical review letters》2007,99(1):011802
Using 14 x 10(6) psi(2S) events accumulated at the BESII detector, we report first measurements of branching fractions or upper limits for psi(2S) decays into gammapp, gamma2(pi+pi-), gammaKS0K+pi-+c.c., gammaK+K-pi+pi-, gammaK*0K-pi++c.c., gammaK*0K*0, gammapi+pi-pp, gamma2(K+K-), gamma3(pi+pi-), and gamma2(pi+pi-)K+K- with the invariant mass of hadrons below 2.9 GeV/c2. We also report branching fractions of psi(2S) decays into 2(pi+pi-)pi0, omegapi+pi-, omegaf2(1270), b1+/-pi-/+, and pi02(pi+pi-)K+K-.  相似文献   
485.
Encapsulation of platinum anticancer drugs by apoferritin   总被引:1,自引:0,他引:1  
Apoferritin derived from the native protein ferritin was employed to encapsulate anticancer drugs cisplatin and carboplatin.  相似文献   
486.
TiO(2)-based photocatalysis has been widely used to decompose various organic pollutants for the purpose of environmental protection. Such a "green" photochemical process can ultimately degrade organic compounds into CO(2) and H(2)O under ambient conditions. We demonstrate here its extended application on the engineering of single- or few-layer graphene. Using a patterned TiO(2) photomask, we have achieved various photochemical tailorings of graphene, including ribbon cutting, arbitrary patterning on any substrate, layer-by-layer thinning, and localized graphene to graphene oxide conversion. UV-visible spectroscopic studies indicate that the photogenerated, highly reactive ·OH radicals work as sharp chemical scissors. Being a solution-free, cost-effective, scalable, and easy handling technique, the presented photocatalytic patterning and modification approach allows for the versatile design and fabrication of graphene-based devices and circuits, compatible with current microelectronic technology, as demonstrated by this fabricated all-carbon field effect transistor (FET) array.  相似文献   
487.
MicroRNA (miRNA) is the negative regulator of gene expression, also known as guide strand of transient miRNA:miRNA* duplex. It is critical in maintaining the normal physiological processes such as development, differentiation, and apoptosis in many organisms. With increasing miRNA data, it is desirable to design methods to identify guide strand based on machine learning algorithms. In this study, the random forest models based on local sequence-structure features were proposed to identify miRNA in four species. The accuracies achieved were 86.51% for Homo sapiens, 81.66% for Ornithorhynchus anatinus, 82.33% for Mus musculus and 85.71% for Schmidtea mediterranea, respectively. Furthermore, the important analysis of feature elements was carried out by using the conditional feature importance strategy. The analysis results revealed that most of the significant elements were related to guanine-cytosine (GC) base pair. We believed that our method could be beneficial to annotate the function of miRNA and help the further understanding of the RNA interference mechanism.  相似文献   
488.
Calixarenes and their derivatives may be a promising material for enzyme immobilization owing to their particular configuration, unique molecule recognition function and aggregation properties. In this paper, p-tert-butylthiacalix[4]arene tetra-amine (TC4TA) was first used as enzyme immobilization material. This attractive material was exploited for the mild immobilization of glucose oxidase (GOD) to develop glucose amperometric biosensor. GOD was strongly adsorbed on the TC4TA modified electrode to form TC4TA/GOD composite membrane. The adsorption mechanism was driven from the covalent bond between amino-group of TC4TA and carboxyl group of GOD and molecule recognition function of TC4TA. Amperometric detection of glucose was evaluated by holding the modified electrode at 0.60 V (versus SCE) to oxidize the hydrogen peroxide generated by the enzymatic reaction. The sensor (TC4TA/GOD) showed a relative fast response (response time was about 5 s), low detection limit (20 μM, S/N = 3), and high sensitivity (ca. 10.2 mA M−1 cm−2) with a linear range of 0.08–10 mM of glucose, as well as a good operational and storage stability. In addition, optimization of the biosensor construction, the effects of the applied potential as well as common interfering compounds on the amperometric response of the sensor were investigated and discussed herein.  相似文献   
489.
Crystallization is commonly used in a separation and purification process in the production of a wide range of materials in various industries. In industry, crystallization usually starts with heterogeneous nucleation on a foreign surface. The complicated mechanism of heterogeneous nucleation is not well understood; however, we hypothesize that there might be a possible correlation between binding affinity to a surface and enhancement of nucleation. Recent studies show that amorphous polymers can be used to control crystallization, selectively produce pharmaceutical polymorphs, and discover novel pharmaceutical polymorphs. To investigate the possible correlation between the binding affinity of one molecule to key binding sites (local binding) and heterogeneous nucleation activity as well as the possibility of using this binding affinity to help guide the selection of polymers that promote heterogeneous nucleation, we computed the free energy of binding of aspirin to four nonporous cross-linked polymers in an ethanol-water 38 v% mixture. These cross-linked polymers are poly(4-acryloylmorpholine) (PAM), poly(2-carboxyethyl acrylate) (PCEA), poly(4-hydroxylbutyl acrylate) (PHBA), and polystyrene (PS); all of them were cross-linked with divinylbenzene (DVB). These systems were used because their heterogeneous nucleation activities are available in literature, and the ranking is PAM > PCEA > PHBA ≈ PS. We generated three independent surfaces for each polymer and computed the free energy of binding of aspirin to the best binding site that we found on each surface. The average free energies of binding to the best sites of PAM, PCEA, PHBA, and PS are -20.4 ± 1.0, -16.7 ± 1.0, -14.4 ± 1.1, and -13.6 ± 1.1 kcal/mol, respectively. We found that the trend of the magnitudes of the average free energies of binding to the best sites is PAM > PCEA > PHBA ≈ PS. This trend is very similar to that of heterogeneous nucleation activity. Our results suggest the importance of the free energy of binding to key sites (local binding) and the possibility of using this quantity to help guide the selection of polymers that promote heterogeneous nucleation.  相似文献   
490.
In this paper, by using the Fourier localization technique and Bony's paraproduct decomposition, we give a regularity criterion of the weak solution to 3D viscous Boussinesq equations in Besov spaces. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   
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