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71.
In the almost 40?years since we wrote Evaluative bibliometrics enormous advances have been made in data availability and analytic technique. The journal impact factor of the 1960s has clearly not kept up with the state of the art. However, for both old and new indicators, basic validity and relevance issues remain, such as by what standard can we validate our results, and what external use can appropriately be made of them? As funding support becomes more difficult, we should not lose sight of the necessity to again demonstrate the importance of our research, and must keep in mind that it is the relevance of our results that count, not the elegance of our mathematics.  相似文献   
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73.
Human salmonellosis is an important food-borne disease and S. Typhimurium is the most common serotype attributed to pork products. Under a farm-to-fork strategy, reducing the levels of Salmonella-positive pigs entering the slaughterhouse is an important goal. A framework model was developed, where the effect of dynamic (infection characteristics) and non-dynamic (cleanness and disinfection, biosecurity measures, etc.) factors were considered. Four baseline scenarios were created, corresponding to different levels associated with national Salmonella monitoring programs, and sensitivity analyses were run for the non-dynamic factors. Moreover, the option of vaccination was incorporated into the model, in order to provide with a tool for the formulation of an optimum vaccination strategy depending on the characteristics of the vaccine.  相似文献   
74.
温压是一种可将增高密度与选择高使用性能材料相结合的技术。增高密度有助于提高零件的力学性能,以及整体使用性能。将密度增高与高使用性能相结合,可使制造的零件的使用性能超过相应的铸锻材料产品,同时可制成具有最终形的零件,从而显著减低生产成本。因此,自动变速器的涡轮毂就成为了温压的一个理想对象。这篇论文将评述,将用于高扭矩自动变速器的常规锻件切削加工的涡轮毂转换为用一次压制/一次烧结制造的粉末冶金涡轮毂。粉末冶金涡轮毂使用的材料是FD-0405。在试验室对这种扩散合金化材料进行了评价,和报告了几个密度水平的力学性能。温压可使高应力的内花键区全面达到高密度。为了证明粉末冶金零件的适用性,进行了广泛的力学与零件的特定试验。  相似文献   
75.
Successful spinal cord repair is thought to be promoted with hierarchically structured scaffolds. These should combine aligned porosity with additional linear features on the micrometer scale to guide axons across multiple length scales. Such scaffolds are generated through the carefully controlled directional solidification of an aqueous biopolymer solution, followed by lyophilization. Under specific freezing conditions this yields a highly regular and aligned lamellar architecture. This architecture exhibits uniform ridges of controlled height and width on the lamellar surface. These ridges run parallel to the pore axis, serving as secondary guidance features. The ridges are capable of linearly aligning 62.4% of chick dorsal root ganglia neurites to within ±10° of the ridge direction. Notably, neurites sprouting perpendicular to the ridge are guided into alignment with these microridged features.  相似文献   
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77.
We explore the theoretical foundations on how firm and IT characteristics explain the market value variations in e-commerce initiatives by examining the announcements of 946 e-commerce initiatives in the public media. Our approach combines the Event study methodology and Decision tree induction to examine the main and interaction effects of IT and firm characteristics on Cumulative Abnormal Returns (CAR). In particular, we generate complex interaction models that can guide e-commerce investment decisions so managers can know, for example, which combination of IT and firm characteristics are more likely to be viewed positively by investors. The selected study variables as well as explanation of the proposed framework are informed by innovation, resource-based view, transaction cost economics and complementarity theories. We have inductively developed a set of propositions that can be deductively tested to assess the validity of our proposed theoretical framework. Hence our study provides an initial roadmap for theory development on e-commerce and CAR.  相似文献   
78.
The adsorption of Aspilia africana extract and subsequent corrosion inhibition of aluminium alloy AA3003 in hydrochloric acid solutions have been investigated using gravimetric and electrochemical techniques. Inhibition efficiency increased with extract concentration and temperature rise. Polarization studies revealed that the extract essentially inhibited the cathodic reaction. An adsorption mechanism involving physisorption and chemisorption of extract constituents at low and high temperatures, respectively, has been proposed from the trend of adsorption-free energies. Quantum chemical computations and molecular dynamics simulations described the individual contributions of some extract constituents to the observed inhibiting effect.  相似文献   
79.
The building blocks of complex biological systems are single cells. Fundamental insights gained from single-cell analysis promise to provide the framework for understanding normal biological systems development as well as the limits on systems/cellular ability to respond to disease. The interplay of cells to create functional systems is not well understood. Until recently, the study of single cells has concentrated primarily on morphological and physiological characterization. With the application of new highly sensitive molecular and genomic technologies, the quantitative biochemistry of single cells is now accessible.  相似文献   
80.
Novel organic/ultrathin low work function metal bilayer cathode buffers for small molecule organic solar cells are proposed. Ultrathin low work function metal layers possess a high built-in electric field for effective carrier extraction and a high cathode reflectivity for maximum absorption in the photoactive layers. This leads to a significant increase of short circuit current density and fill factor of cells. By integrating this bilayer cathode buffer with DTDCTB:C60 small molecular heterojunction, the device exhibits a high power conversion efficiency of up to 5.28%, which is an improvement of 22% compared to a device with a traditional single organic layer buffer.  相似文献   
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