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排序方式: 共有641条查询结果,搜索用时 15 毫秒
71.
Deelstra Janna T.; Peeters Maria C. W.; Schaufeli Wilmar B.; Stroebe Wolfgang; Zijlstra Fred R. H.; van Doornen Lorenz P. 《Canadian Metallurgical Quarterly》2003,88(2):324
Although the role of social support in promoting employees' health and well-being has been studied extensively, the evidence is inconsistent, sometimes even suggesting that social support might have negative effects. The authors examined some psychological processes that might explain such effects. On the basis of the threat-to-self-esteem model, the authors tested the hypothesis that receiving imposed support elicits negative reactions, which are moderated by someone's need for support. The authors distinguished 3 different reactions: (a) self-related, (b) interaction-related, and (c) physiological. The results of an experiment with 48 temporary administrative workers generally confirmed the hypothesis. Imposed support elicited negative reactions, except when there was an unsolvable problem, but even then the effect of imposed support was not positive but neutral. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
72.
Hendrik Schbe 《Quality and Reliability Engineering International》1990,6(5):341-344
In the following paper we present a new model for crack propagation. The new model is able to involve sudden growth of crack length (jumps) and is a generalization of the well-known Paris–Erdogen law. We obtain the lifetime distribution and the residual lifetime distributions. 相似文献
73.
Rudy Van Cauwenbergh Peter Hendrix H. Robberecht Hendrik Deelstra 《Zeitschrift für Lebensmitteluntersuchung und -Forschung A》1997,205(1):1-4
For the first time daily dietary molybdenum intake in Belgium has been evaluated by duplicate portion sampling, heating in
a microwave oven for destruction and atomic absorption spectrometric determination of this element. The mean intake value
(87±11 μg/day) is lower than levels found for most other countries and is situated at the lower end of the recommended range
for a safe and adequate daily dietary intake.
Received: 14 October 1996 相似文献
74.
Hilde Grove Hendrik W. Brinks Ole M. Lvvik Richard H. Heyn Bjrn C. Hauback 《Journal of Alloys and Compounds》2008,460(1-2):64-68
LiMgAlH6 is the intermediate phase when LiMg(AlH4)3 is heated. It contains 9.4 wt.% hydrogen, of which 4.8 wt.% is released during the decomposition step to MgH2 and LiH. Deuterated LiMgAlD6 was prepared by heat-treating LiMg(AlD4)3 at 130 °C. Powder neutron and synchrotron X-ray diffraction patterns were measured and the structure was refined using the Rietveld technique on both patterns simultaneously. LiMgAlD6 crystallizes in the trigonal space group P321 with a = 7.9856(4) Å and c = 4.3789(3) Å. The structure consists of isolated AlD6 octahedra connected through octahedrally coordinated Mg- and Li-atoms. 相似文献
75.
76.
H. Robberecht D. Vanden Berghe H. Deelstra R. Van Grieken 《The Science of the total environment》1982,25(1):61-69
Data obtained by atomic absorption spectroscopy showed a selenium concentration of only 0.11 ppm as an average value for the most representative agricultural soils in Belgium. The selenium content in rye-grass grown on different soil types was between 0.05 and 0.11 ppm, and positively correlated with the soil selenium level.Addition of selenium in the form of selenite to the different soil types resulted in an increased selenium uptake by the plant. The ultimate concentration in the plant depended on the structural and chemical composition of the soil. Twelve other elements were determined in the soils by energy-dispersive X-ray fluorescence; none showed a strong correlation with the soil selenium content or with the selenium uptake by ryegrass. 相似文献
77.
The two best known coal composition charts are Seyler's plot of mass percent hydrogen versus mass percent carbon, which has been much used for coal classification, and van Krevelen's plot of atomic H/C ratio versus O/C ratio, which has proved useful in the study of coalification. For the more general problem of the study of conversion of coal to other materials it is suggested that a ternary carbon/ hydrogen/oxygen diagram be used. In particular it is advocated that the compositions be plotted as bond-equivalent percentages, i.e. with each element given a weighting appropriate to its power of combining with the other elements. The construction and use of the diagram are demonstrated, taking as an example the problem of the conversion of brown coal to oil. 相似文献
78.
Klaas B. Klaassen Jacques C.L. van Peppen Hendrik J. Jansen 《Microelectronics Reliability》1978,17(1):35-40
When applying redundancy, the system designer may find himself facing the dilemma of weighing the better life prospects of passive redundant hardware against the lower system complexity in the case of active redundant hardware. This dilemma is analyzed here by comparing the MTTF and the reliability obtained with active, stand-by and passive redundancy. The analysis makes use of Markov diagrams and a generalized reliability model that embraces all three types of redundancy and covers all types of failure which can occur in practice. 相似文献
79.
Lemay SG van den Broek DM Storm AJ Krapf D Smeets RM Heering HA Dekker C 《Analytical chemistry》2005,77(6):1911-1915
We report a new technique for fabricating electrodes for electrochemical applications with lateral dimensions in the range 15-200 nm and a reproducible, well-defined geometry. This technique allows determining the electrode size by electron microscopy prior to electrochemical measurements and without contamination of the metal electrode. We measured the diffusion-limited current with stepped-current voltammetry and showed that its dependence on electrode size can be quantitatively understood if the known geometry of the electrodes is explicitly taken into account. 相似文献
80.