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排序方式: 共有6821条查询结果,搜索用时 15 毫秒
1.
2.
An evaluation of the Spanish CSIC performance in Biotechnology, as compared with those of the French CNRS and the Italian
CNR, has been carried out to determine the balance between the generation of scientific knowledge and the transfer of technology.
This study shows a high scientific productivity mostly in journals with moderate impact factor, a low generation of patents
and an insufficient transfer of knowledge to the Spanish companies. Other indicators confirm the existence of competitive
human resources in biotechnological research producing scientific knowledge of interest for the development of patents and
that cooperates successfully at European level. 相似文献
3.
The effects of cooking temperature, time and temperature of brine-salting, and temperature of ripening on the behavior of Enterobacteriaceae in Manchego cheese were studied. Fifty lots of cheese from raw ewe's milk manufactured and ripened under different conditions were investigated throughout a 60-day ripening period. Differences in pH values due to temperature-dependent whey retention accounted for the effect of cooking temperature on coliform and fecal coliform counts. Temperature of brine-salting had no effect on Enterobacteriaceae counts, but a significant effect of salting time on Enterobacteriaceae and fecal coliform counts was detected. Ripening temperature was the manufacturing variable with greatest influence (P<.01) on Enterobacteriaceae and coliform counts during the whole curing period. 相似文献
4.
5.
Renato Cataluña Rosângela da Silva Eliana Weber de Menezes Ricardo Boeira Ivanov 《Fuel》2008,87(15-16):3362-3368
Oxygenated fuels increase fuel consumption due to their low enthalpy of combustion; however, their high antiknock index renders them suitable for use in engines with a high compression rate, increasing their thermal yield. This study evaluated the performance of biorenewable oxygenated fuels (ethanol and isoamyl alcohol) and partially renewable fuels (ETBE: ethyl tert-butyl ether, TAEE: tert-amyl ethyl ether and di-TAE: di-tert-amyl ether) with high degree of purity and in mixtures with automotive gasoline, based on tests with Otto cycle engines. Among the oxygenated fuels evaluated here, di-TAE was found to present the best characteristics of performance, both individually and in mixtures with gasoline. 相似文献
6.
The nonisothermal crystallization kinetics of a metallocene-made isotactic polypropylene (m-iPP) and its compounds with 0.1 wt % and 0.3 wt % of a sorbitol derivative [1,3:2,4-bis(3,4-dimethylbenzylidene)sorbitol (DMDBS); an α nucleator] were investigated by differential scanning calorimetry at different cooling rates from the melt. The nucleation efficiency was proved by a significant increase in the crystallization temperatures (accompanied by a slight augmentation of the degree of crystallinity and a decrease in the crystal sizes). This increase in the crystallization temperatures led to higher amounts of fractional content in the γ polymorph, even though DMDBS was supposed to be a nucleator for the α form. The Avrami and Ozawa methods effectively described only the early stage of crystallization, whereas a combined Avrami–Ozawa method was valid for the whole crystallization process. The values of the exponent for this method decreased for nucleated samples in the later stage of crystallization, especially in the case of m-iPP with 0.3 wt % DMDBS added (m-iPP03). The activation energy of the process and the surface free energy were also estimated. The production of considerable proportions of the γ polymorph in m-iPP03 corresponded to higher values of the activation energy and lower values of the surface free energy. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 相似文献
7.
The Humanitarian Engineering initiative, sponsored by the William and Flora Hewlett Foundation, at the Colorado School of Mines, is creating a program that will support engineering students in understanding their responsibility for solving community development problems that exist throughout the world. As part of this effort, data has been collected on faculty and student attitudes using the ‘Community Service Attitudes Scale,” developed and validated by Shiarella, McCarthy, and Tucker. During the fall 2004, 78 students and 34 faculty members responded to this instrument. Statistically significant differences were found between the attitudes of students and faculty, males and females, and among different age groupings with respect to service activities. A general finding was that faculty displayed better attitudes toward community service than the students. 相似文献
8.
This article presents the first application of the Finite Calculus (FIC) in a Ritz-FEM variational framework. FIC provides a steplength parametrization of mesh dimensions, which is used to modify the shape functions. This approach is applied to the FEM discretization of the steady-state, one-dimensional, diffusion–absorption and Helmholtz equations. Parametrized linear shape functions are directly inserted into a FIC functional. The resulting Ritz-FIC equations are symmetric and carry a element-level free parameter coming from the function modification process. Both constant- and variable-coefficient cases are studied. It is shown that the parameter can be used to produce nodally exact solutions for the constant coefficient case. The optimal value is found by matching the finite-order modified differential equation (FOMoDE) of the Ritz-FIC equations with the original field equation. The inclusion of the Ritz-FIC models in the context of templates is examined. This inclusion shows that there is an infinite number of nodally exact models for the constant coefficient case. The ingredients of these methods (FIC, Ritz, MoDE and templates) can be extended to multiple dimensions 相似文献
9.
José Luis Montañez-Soto Salvador Alegret Juan Alfredo Salazar-Montoya Emma Gloria Ramos-Ramírez 《European Food Research and Technology》2006,223(3):379-386
In this work a novel amperometric biosensor for fructose determination in solutions was developed. The device was constructed by the incorporation of a tetrathiofulvalene-tetracyanoquinodimethane organic conducting salt and fructose dehydrogenase enzyme, include in a polymeric matrix of epoxy resin and graphite powder. Because of the electrocatalytic function of the salt, the direct transfer of the electron between the reduced prosthetic group (PQQH2) of the enzyme and the transducing material, was verified at a low working potential (150 mV vs. Ag/AgCl), where the interfering reactions were minimized. The response time at 90% of the steady state value was less than 20 s. The current response was directly proportional to the D-fructose concentration from 0.01 to 0.3 mmol/l with a detection limit of 0.005 mmol/l (signal/noise of 3) and a sensitivity of 1.9985 μA/mmol. The biosensor sensitivity diminishes when its surface is not polished between successive determinations, and remains constant (rsd=1.85, n=10) when the surface is polished between determinations. The effects of temperature and pH on the biosensor response were studied and analyzed; also the properties of the enzyme (Km
ap, I
max, Q10) were determinate in this work. The biosensor was used to determine fructose in high fructose syrups and there were not significant differences between these results and those obtained by HPLC (p≤0.05). During 4 months, in intermittent determinations the biosensor kept 100% of its original sensitivity and after 18 months stored at 4°C, it only lost 32% of its sensitivity. The simplicity, low working potential, high stability and good performance of this biosensor shows a great potential for its use in the fructose determination. 相似文献
10.
Robin M. Giblin-Davis Jorge E. Peña A. C. Oehlschlager Alice L. Perez 《Journal of chemical ecology》1996,22(8):1389-1410
Response of adults of the West Indian sugarcane weevil,Metamasius hemipterus sericeus, to various semiochemical treatments and physical trap designs was studied in southern Florida in field-grown banana and Canary Island date palms. Ethyl acetate released alone at 860–1007 mg/day was as effective for the capture ofM. h. sericeus as a combination of ethyl acetate (844–919 mg/day), ethyl propionate (348–362 mg/day), and ethyl butyrate (117–137 mg/day) and in one trial was more effective than fermenting sugarcane (250 g), ethyl propionate alone (353–384 mg/day), ethyl butyrate alone (123–174 mg/day), or no treatment. Ethyl acetate released alone at 675–683 mg/day was as attractive as 250 g of fermenting sugarcane or the racemic blend of the male-produced aggregation pheromones [(±)-5-methyl-nonan-4-ol and (±)-2-methyl-heptan-4-ol (8:1 ratio) “metalure”] at 3 mg/day. Weevil counts increased with binary combinations of ethyl acetate, sugarcane, and/or metalure over these treatments alone and the ternary combination was two to three times more effective than any of the binary treatments. Attraction to ethyl acetate released alone at 777 mg/day with metalure was greater than to the hydrolysis products of ethyl acetate (ethanol and/or acetic acid each released at about 6–8 mg/day) with metalure. Weevil counts from traps baited with 250 g of sugarcane and metalure increased with increasing dose of ethyl acetate to about 400 mg/day and then appeared to plateau. Ethyl acetate (about 700 mg/day) and metalure increased weevil counts in traps with increasing amounts of sugarcane (0–2 kg). Molasses (45 g) + water (158 ml) substitutes for sugarcane were about as effective for capturingM. h. sericeus as 250 g of fermenting sugarcane [all treatments with ethyl acetate (847 mg/day) and metalure]. Early experiments used a lethal pitfall trap. We demonstrated that several alternative trap designs were more effective than the lethal pitfall trap for capturing weevils. Color and height (on ground vs. 1 m on pole) did not affect trap efficacy when baited with the ternary combination of ethyl acetate (672–825 mg/day), sugarcane (250 g), and metalure. 相似文献