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971.
长柄串珠藻生理生态特性的研究 总被引:2,自引:0,他引:2
孙存华刘晓峰刘贤德郭晓薇郭东城徐金平刘晓燕华栋 《资源科学》2001,23(3):93-96
长柄串珠藻是一种要求水温较低且恒定并适应光强较弱的小型淡水红藻,生存于Ph7.5,夏天水温为17°C ,冬天水温为14°C ,全年水温波动不大,钙含量较高而其它营养盐分含量较低的泉水中。奇光合作用的最适水温为15°C ,光合作用的适宜强光为30μmol/m2.s-50μmol/m2.s,最适光强度为35μmol/m2.s-45μmol/m2.s,40μmol/m2.s光合速率最高峰,为其饱和光强。长柄串珠藻的光补偿点随温度的升高而升高,5°C、10°C、15°C、20°C和25°C的光补偿点分别为4.5μmol/m2.s、5μmol/m2.s、5.6μmol/m2.s、6μmol/m2.s和7μmol/m2.s。呼吸速率在光合速率增大时也升高,且与水温正相关 相似文献
972.
Erik J. de Vries 《Research Policy》2006,35(7):1037-1051
Three approaches of studying innovation in services are recognized: the assimilation, demarcation and synthesis approach. The synthesis approach attempts to arrive at a theory relevant for service and manufacturing. Gallouj and Weinstein [Gallouj, F., Weinstein, O., 1997. Innovation in services. Research Policy 26, 537-556] were one of the first to take this approach. This article contributes to the synthesis approach by revising their theory to enable reasoning about recent innovation trends in networks of organizations and in the distribution of services. The theory revision is based on several case studies. Implications for the study of innovation are discussed in terms of results from recent demarcation studies. 相似文献
973.
974.
当科学与宗教在古希腊神示所狭路相逢,它们的关系比学者们原先预想的要融洽得多. 举世闻名的阿波罗神殿,座落在希腊德尔斐风景如画的山区,是古希腊最重要的宗教场所,因为法力无边的德尔斐神示所就在这座神殿里.在重男轻女的古希腊异乎寻常的是,Pythia必须是女性,而且职位的继承与家族的显赫无关. 相似文献
975.
流程重组的多维性:中国企业变革的特点 总被引:2,自引:0,他引:2
“流程重组”作为一种激进地改变企业、提高企业竞争力的方式得到社会的广泛关注。但是,从实施的效果以及人们对哈默思想的理解看,与哈默等的设想有较大的距离。流程重组这一出自美国的概念在与中国的企业管理实践相结合时有较多的不尽人意之处,根据我们对江苏省近十家企业和企业集团重组实践的考察,企业的变革与重组在中国企业中具有并不局限于“流程”的丰富内涵,将流程重组概念发展为包含制度、信息、知识等内容的多维重组过程将更能反映中国企业变革的特点。 相似文献
976.
Vicente P. Guerrero-Bote Felipe Zapico-Alonso María Eugenia Espinosa-Calvo Rocío Gmez Crisstomo Flix de Moya-Anegn 《Information processing & management》2006,42(6):1484
The Pathfinder algorithm is widely used to prune social networks. The pruning maintains the geodesic distances between nodes. It has shown itself to be very useful in the analysis of, amongst others, citations in BIS (bibliometrics, informetrics, and scientometrics). It has even been proposed for the online display of the search results in an information retrieval system. However, its great time and space complexity limits its use in real-time applications and in networks of any considerable size.The present work describes an improved algorithm with considerably reduced time and space complexity. Its lower execution costs thus increase its applicability both in real time and to large networks. 相似文献
977.
This paper uses a unique data set of Mexican researchers to explore the determinants of research output and impact. Our findings confirm a quadratic relationship between age and the number of published papers. However, publishing peaks when researchers are approximately 53 years old, 5 or 10 years later than what prior studies have shown. Overall, the results suggest that age does not have a substantial influence on research output and impact. We also find that reputation matters for the number of citations but not publications. Results also show important heterogeneity across areas of knowledge. Interpretations of other aspects, such as gender, country of PhD, and cohort effect, among others, are also discussed. 相似文献
978.
Elefthrios Sapsalis Bruno van Pottelsberghe de la Potterie Ran Navon 《Research Policy》2006,35(10):1631-1645
This paper compares corporate and academic patents and tests whether they have similar value distributions and share common determinants of value. The empirical results based on an in-depth analysis of 400 biotech patents applied for by Belgian universities and firms lead to the following observations: (i) academic and corporate patent value distributions have similar levels of ‘skewness’; (ii) the identification of the institutional origin of knowledge allows for an improved understanding of the value determinants and (iii) there is a need to stimulate star scientists to codify their tacit knowledge into valuable patents. 相似文献
979.
A connectionist method for autotuning the free parameter of a fractional-order hold (FROH) circuit in order to improve the performance of the digitally controlled systems is proposed. Such a technique employs multilayer perceptrons to approximate the mapping between the sampling period/continuous-time parameters of the estimated plant and the optimal value of the FROH adjustable gain. In this way, adaptive discretization systems to improve the stability properties of the resulting discrete-time zeros are implemented. Simulation results are presented in order to illustrate the properties of the complete system applied to two actual digitally controlled printing devices (HP 7090A and low-cost computer printer). 相似文献
980.
Evaristo Jiménez-Contreras Félix de Moya AnegónEmilio Delgado López-Cózar 《Research Policy》2003,32(1):123-142
This article outlines the evolution of international scientific production in Spain over the last 25 years, a period characterised by steady growth in research production. The following stages in this process are identified in accordance with some of the factors that predominated at different times. From 1974 to 1982 production increased due to causes endogenous to the scientific system itself, as scientists brought their work into line with the patterns which characterised research in other industrialised countries. From 1982 to 1991 the prioritisation of R&D by government administrative bodies represented a constant stimulus, implemented through a set of legal measures, investments and the creation of posts for new researchers. From 1989 to the present the creation of the Comisión Nacional de Evaluación de la Actividad Investigadora (National Commission for the Evaluation of Research Activity, CNEAI) and the research incentive system have provided a further stimulus, which has led to the maintenance of, and an increase in, the rate of research production in spite of the net decrease in the monetary value of research grants awarded during the last period analysed. Other special characteristics of Spanish research, such as its dependence on the public sector and its essentially academic nature, are discussed. 相似文献