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71.
China has taken a foreign direct investment‐based approach toward increasing its capital and knowledge base, and developing into an innovative economy. However, little quantitative evidence exists about the factors that drive innovations of foreign‐invested enterprises (FIEs) there. This paper uses survey data from high‐technology firms in Shanghai to discuss factors affecting their innovativeness. It takes the concepts of absorptive capacity, export orientation, and innovation‐related cooperation as a starting point. It highlights how the interplay of strategies and resources affects innovativeness and heterogeneity of FIEs. The most innovative FIEs are endowed with a strong human capital base and R&D activities, which at the same time target export markets and whose cooperative partners involve firms other than their parent company. The results underline the necessity to differentiate between the different types of FIEs when examining their innovativeness.  相似文献   
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Pericarp color in wheat is an important trait related to nutrients and health benefits. Identification of molecular markers closely linked to the grain color genes will help utilize pericarp trait in wheat breeding. Genetic studies involving F1, F2, and F3 populations from the cross Jizi 439 (purple grain)/Gao8901 (white grain) showed that the purple grain color was controlled by two genes. By using the bulked segregant analysis (BSA) approach, two DNA pools were established from the dark purple-grain and white-grain plants respectively. Among the 230 pairs of microsatellite primers used in this study, two markers showed polymorphism in DNA pools, parents, F1 and F2 populations. Linkage analysis indicated that the two markers Xgwm47 and Xgwm155 were linked with two purple pigment genes. One of the purple pigment genes is located on chromosome 2AS and is 34.7cM away from the marker Xgwm47, whereas another gene is mapped on 3AL with 14.7cM away from marker Xgwm155.  相似文献   
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76.
Living in poverty is associated with high levels of protracted stress associated with health problems. Economic and food insecurity are particularly poignant aspects of poverty and condition the work of securing basic daily needs of families. Recent studies suggest that levels of stress increase as family food needs rise. This paper presents new findings which clarify the relationship of food provisioning to stress levels, by examining actual food provisioning strategies and food insecurity among the Northern Cheyenne Indians of southeastern Montana. Results clearly show that stress varies by types of food acquisition strategies. Contrary to our expectations, more complex strategies, including relatively unpredictable and cumbersome food provisioning activities, are not linked to higher stress levels in our analysis. Controlling for food security levels, households using a combination of local programs and informal subsistence sources are the least stressed, despite the demands of managing a large number of food sources. Households primarily using Food Stamps are the most likely to experience high levels of stress. Interviews with Food Stamp recipients show that potential sources of stress include inadequate allocations of Food Stamps, difficulty achieving and maintaining eligibility, challenges to complying with paperwork and appointment requirements, as well as personal obstacles and community barriers to making food stamps last. Analyses indicate that contradictions between local cultural norms for food provisioning and the realities of food insecurity in this context promote strategies emphasizing greater independence from federal food programs.  相似文献   
77.
To select a reliable and sensitive method for discriminating strains of Porphyra haitanensis, the nucleotide sequence of the internal transcribed spacer 1 to internal transcribed spacer 2 regions (ITS-5.8S) of nuclear ribosomal DNA and the intergenic spacer region of RUBISCO were compared in five wild and five cultivated Porphyra haitanensis strains. Based on molecular analyses, sequences of ITS-5.8S (about 1,210 bp) could be divided into three regions: ITS1, 5.8S, and ITS2. The ITS1 and ITS2 sequences of each strain differed, even between individuals collected from the same site. In contrast, 5.8S rDNA and RUBISCO spacer sequences were identical among the ten P. haitanensis strains, although differences were found among different Porphyra species. Phylogenetic analysis also supported these conclusions. These sequence features of highly conserved regions and diversified regions that occurred repeatedly in ITS-5.8S could be useful in discriminating germplasm of P. haitanensis strains or Porphyra species. In contrast, the RUBISCO spacer is only suitable for identifying Porphyra species. New coupled primers were designed to amplify only the 5.8S rDNA and ITS2 region of Porphyra. The sequences of these amplified fragments can be readily used to identify germplasm or to perform phylogenetic analysis of Porphyra spp.  相似文献   
78.
A study was conducted to investigate the effects of skid trail slope and traffic levels on soil disturbances at two soil depths (0–10 and 10–20 cm). The treatments were set at four traffic levels (2, 7, 12 and 20), two slope classes (<20% and >20%) and two soil depths (0–10 and 10–20 cm). Results show that skidder traffic, longitudinal slope and soil depth have significant effect on soil bulk density in skid trail. Comparison of average soil bulk density in different traffic levels shows that there are significant differences in average bulk density between different traffic levels and control (p<0.05). The average bulk densities in different slopes and soil depths are significantly increased with increase in traffic levels, maximized at 12 passes (p<0.05), but there are no significant differences between 12 and 20 passes. The interaction effects between traffic and soil depth are significant (F 0.05,3=0.109, p<0.001). For all traffic treatments, there are significant differences in soil moisture content between the two slope classes and the two depths (p<0.001). However, the interaction effects between traffic levels and slope classes are not significant (p >0.05), although skidder traffic and slope affected soil moisture content.  相似文献   
79.
Since 1900, soil organic matter (SOM) in farmlands worldwide has declined drastically as a result of carbon turnover and cropping systems. Over the past 17 years, research trials were established to evaluate the efficacy of different commercial humates products on potato production. Data from humic acid (HA) trials showed that different cropping systems responded differently to different products in relation to yield and quality. Important qualifying factors included: source; concentration; processing; chelating or complexing capacity of the humic acid products; functional groups (Carboxyl; Phenol; Hydroxyl; Ketone; Ester; Ether; Amine), rotation and soil quality factors; consistency of the product in enhancing yield and quality of potato crops; mineralization effect; and influence on fertilizer use efficiency. Properties of humic substances, major constituents of soil organic matter, include chelation, mineralization, buffer effect, clay mineral-organic interaction, and cation exchange. Humates increase phosphorus availability by complexing ions into stable compounds, allowing the phosphorus ion to remain exchangeable for plants’ uptake. Collectively, the consistent use of good quality products in our replicated research plots in different years resulted in a yield increase from 11.4% to the maximum of 22.3%. Over the past decade, there has been a major increase in the quality of research and development of organic and humic acid products by some well-established manufacturers. Our experimentations with these commercial products showed an increase in the yield and quality of crops.  相似文献   
80.
The hollowness of crosslinked hollow phenolic fibers was regulated successfully from 9 % to 80 % by adjusting the curing temperature of the partially crosslinked fibers. The partially crosslinked fibers was studied in detail by mass gained, tensile strength, solvent dissolution, SEM, IR, and TG analysis, and the prepared hollow phenolic fibers with different degrees of hollowness were characterized with SEM, tensile strength, TG-DSC and TG-MS. The results show that the factor determining the hollowness is the crosslinked extent of the partially crosslinked fibers and the hollow fibers with different degrees of hollowness have similar crosslinkage, mechanical properties and thermal stability.  相似文献   
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