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排序方式: 共有26条查询结果,搜索用时 265 毫秒
1.
In this paper it is shown that the unweighted arithmetic average is the theoretically consistent scheme to aggregate composite indicators, derived from the benefit-of-the-doubt model, across decision-making units.  相似文献   
2.
In this note we derive alternative weighting schemes that complement those of Färe and Zelenyuk (2003) for consistent aggregation of Farrell efficiencies when the technology exhibits (global) constant returns to scale.  相似文献   
3.
The endohedral fullerene Y3N@C80 exhibits luminescence with reasonable quantum yield and extraordinary long lifetime. By variable‐temperature steady‐state and time‐resolved luminescence spectroscopy, it is demonstrated that above 60 K the Y3N@C80 exhibits thermally activated delayed fluorescence with maximum emission at 120 K and a negligible prompt fluorescence. Below 60 K, a phosphorescence with a lifetime of 192±1 ms is observed. Spin distribution and dynamics in the triplet excited state is investigated with X‐ and W‐band EPR and ENDOR spectroscopies and DFT computations. Finally, electroluminescence of the Y3N@C80/PFO film is demonstrated opening the possibility for red‐emitting fullerene‐based organic light‐emitting diodes (OLEDs).  相似文献   
4.
Three-dimensional studies on bicomponent extrusion   总被引:1,自引:0,他引:1  
The present work is concerned with the mathematical modelling and numerical simulation of three-dimensional (3-D) bicomponent extrusion. The objective is to provide an understanding of the flow phenomena involved and to investigate their impact on the free surface shape and interface configuration of the extruded article. A finite element algorithm for the 3-D numerical simulation of bicomponent stratified free surface flows is described. The presence of multiple free surfaces (layer interface and external free surfaces) requires special free surface update schemes. The pressure and viscous stress discontinuity due to viscosity mismatch at the interface between the two stratified components is handled with both a double node (u–v–w–P 1 –P 2 –h 1 –h 2) formulation and a penalty function (u–v–w–P–h 1 –h 2) formulation.The experimentally observed tendency of the less viscous layer to encapsulate the more viscous layer in stratified bicomponent flows of side-by-side configuration is established with the aid of a fully 3-D analysis in agreement with experimental evidence. The direction and degree of encapsulation depend directly on the viscosity ratio of the two melts. For shear thinning melts exhibiting a viscosity crossover point, it is demonstrated that interface curvature reversal may occur if the shearing level is such that the crossover point is exceeded. Extrudate bending and distortion of the bicomponent system because of the viscosity mismatch is shown. For flows in a sheath-core configuration it is shown that the viscosity ratio may have a severe effect on the swelling ratio of the bicomponent system.Modelling of the die section showed that the boundary condition imposed at the fluid/fluid/wall contact point is critical to the accuracy of the overall solution.  相似文献   
5.
We prove a density version of the Halpern–Läuchli Theorem. This settles in the affirmative a conjecture of R. Laver.  相似文献   
6.
The occurrence of N‐glycans with a bisecting GlcNAc modification on glycoproteins has many implications in developmental and immune biology. However, these particular N‐glycans are difficult to obtain either from nature or through synthesis. We have developed a flexible and general method for synthesizing bisected N‐glycans of the complex type by employing modular TFAc‐protected donors for all antennae. The TFAc‐protected N‐glycans are suitable for the late introduction of a bisecting GlcNAc. This integrated strategy permits for the first time the use of a single approach for multiantennary N‐glycans as well as their bisected derivatives via imidates, with unprecedented yields even in a one‐pot double glycosylation. With this new method, rare N‐glycans of the bisected type can be obtained readily, thereby providing defined tools to decipher the biological roles of bisecting GlcNAc modifications.  相似文献   
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In modern biology, the correct identification of cell types is required for the developmental study of tissues and organs and the production of functional cells for cell therapies and disease modeling. For decades, cell types have been defined on the basis of morphological and physiological markers and, more recently, immunological markers and molecular properties. Recent advances in single-cell RNA sequencing have opened new doors for the characterization of cells at the individual and spatiotemporal levels on the basis of their RNA profiles, vastly transforming our understanding of cell types. The objective of this review is to survey the current progress in the field of cell-type identification, starting with the Human Cell Atlas project, which aims to sequence every cell in the human body, to molecular marker databases for individual cell types and other sources that address cell-type identification for regenerative medicine based on cell data guidelines.Subject terms: Stem-cell research, Differentiation, Translational research, Classification and taxonomy, Stem-cell differentiation  相似文献   
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10.
This paper presents new web-based educational software (webNetPro) for Linear Network Programming. It includes many algorithms for Network Optimization problems, such as shortest path problems, minimum spanning tree problems, maximum flow problems and other search algorithms. Therefore, webNetPro can assist the teaching process of courses such as Graph Theory or Network Optimization, Algorithms or Data Structures. Since the Matlab web server is part of the underlying infrastructure, the end user need not use Matlab directly. The approach exploits transparently the benefits of the Matlab programming environment through a straightforward web interface. Furthermore, webNetPro is platform independent. Thus, it can be viewed as a powerful supplement to traditional instruction techniques and can be used without significant difficulties in distance education. Benefits and drawbacks are thoroughly described in order to support the significance of this tool in distance learning.  相似文献   
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