In order to let the supplier make more reasonable supply decisions,an integrated continuous replenishment policy for the vendor-managed inventory system is presented,which considers the quantity-based shipment consoli...In order to let the supplier make more reasonable supply decisions,an integrated continuous replenishment policy for the vendor-managed inventory system is presented,which considers the quantity-based shipment consolidation and stock replenishment with lead time.Then the system cost is analyzed and a mathematical model is built.Since the model is rather complex,the bounds of the optimal policy are first attained,then the problem is solved by a heuristic algorithm.Through experiments the relationship between the order lead time and the corresponding integrated policy is discussed,and the influence on the system cost is also analyzed.The results reveal that the lead time's influence on the system is more serious with the increase of the order lead time,the integrated policy with the order lead time is more reasonable and the optimal policy can minimize the total system cost.Finally,the parameter sensitivity of the model is analyzed.展开更多
To understand the responses of a freshwater ecosystem to the impoundment of the Three Gorges Reservoir （TGR）, phytoplankton was monitored in the tributaries of the TGR area. From August 2010 to July 2011, algal spec...To understand the responses of a freshwater ecosystem to the impoundment of the Three Gorges Reservoir （TGR）, phytoplankton was monitored in the tributaries of the TGR area. From August 2010 to July 2011, algal species composition, abundance, chlorophyll a and other environmental parameters were investigated in the Gaolan River, which is a tributary of Xiangxi River. Thirty-one algal genera from seven phyla were identified. Results show that the lowest concentrations of total phosphorus （TP） and total nitrogen （TN） were 0.06 mg/L and 1.08 rag/L, respectively. The values of TP and TN exceeded the threshold concentration of the eutrophic state suggested for freshwater bodies. In the Gaolan River, the succession of phytoplankton showed clear seasonal characteristics. Different dominant species were observed among seasons under the control of environment factors. In spring and summer, the dominant species were Nitzschia sp. and Aphanizomenon flos-aquae （L.） Ralfs, the limiting nutrient was NO3^--N, and the key environmental factor for phytoplankton population succession was water temperature （WT）. In autumn and winter, the dominant species were A.flos-aquae and Chlorella sp., the limiting nutrient was pO3--P, and the key environmental factors were transparency and WT. This study illustrates the influence of physical and chemical factors on phytoplankton seasonal succession in a tributary of TGR since the downstream regions of Xiangxi River and Gaolan River became reservoirs after impoundment of the Three Gorges Dam. We suggest that this activity has significantly affected water quality in the dam area.展开更多
Though collocations have drawn much attention in the field of language acquisition, difficulties with them have not been investigated in much detail. This paper reports on a corpus-based exploratory study that analyze...Though collocations have drawn much attention in the field of language acquisition, difficulties with them have not been investigated in much detail. This paper reports on a corpus-based exploratory study that analyzes the mistakes learners made when they produced English collocations. The current study shows that not only beginners but also advanced learners have difficulties in choosing the right collocates and the difficulties that learners of different levels have are more or less the same. The L1 influence on the production of L2 collocations exists at every stage of learning though it varies with the learners' L2 competence.展开更多
Objective: To assess the effects of Tai Chi (Chinese shadow boxing exercise) for improving the lower-limb muscle strength in elderly people. Methods: The PUBMED database (from 1950), EMBASE-ASP database (from 1974), C...Objective: To assess the effects of Tai Chi (Chinese shadow boxing exercise) for improving the lower-limb muscle strength in elderly people. Methods: The PUBMED database (from 1950), EMBASE-ASP database (from 1974), Cochrane Library (from 1991), Elsevier sciences database (from 1990), OVID full text database (from 1997), Springer-link database (from 1997), The National Research Register database, ISI Web of knowledge (from 1963), Chinese Medical Citation Index/Chinese Medical Current Contents (CMCI/CMCC, from 1989), China Knowledge Resource Integrated Database (CNKI, from 1915),VIP database (from 1989), and Wanfang database (from 1977) have been searched only for the English and Chinese literatures updated to 10-30-2010. Two researchers independently assessed the methodological quality of studies, extracted and checked the data one another according to the include/exclude standards. Disagreement was resolved by discussions or with the third person. The Review Manage Software 5.0 was used for Meta-analysis. Results: Eventually, 2 randomized controled studies and 2 non-randomized controled studies met the inclusion criteria, with 163 subjects involved in the present meta-analysis. The meta-analysis demonstrated that Tai Chi exercise could improve the ankle flexor/extensor muscle strength and the knee extensor/flexor muscle strength, tested with an isokinetic dynamometer. The limb muscle strength increased significantly after Tai Chi exercise (P<0.01). Conclusion: The meta-analysis favours Tai Chi exercise for improving the lower-limb muscle strength in the older people.展开更多
基金The National Key Technology R&D Program of China during the 11 th Five-Year Plan Period(No.2006BAH02A06)
文摘In order to let the supplier make more reasonable supply decisions,an integrated continuous replenishment policy for the vendor-managed inventory system is presented,which considers the quantity-based shipment consolidation and stock replenishment with lead time.Then the system cost is analyzed and a mathematical model is built.Since the model is rather complex,the bounds of the optimal policy are first attained,then the problem is solved by a heuristic algorithm.Through experiments the relationship between the order lead time and the corresponding integrated policy is discussed,and the influence on the system cost is also analyzed.The results reveal that the lead time's influence on the system is more serious with the increase of the order lead time,the integrated policy with the order lead time is more reasonable and the optimal policy can minimize the total system cost.Finally,the parameter sensitivity of the model is analyzed.
基金Supported by the National Major Programs of Water Body Pollution Control and Remediation(No.2012ZX07103003-02)the National Basic Research Program of China(973 Program)(No.2008CB418000)
文摘To understand the responses of a freshwater ecosystem to the impoundment of the Three Gorges Reservoir （TGR）, phytoplankton was monitored in the tributaries of the TGR area. From August 2010 to July 2011, algal species composition, abundance, chlorophyll a and other environmental parameters were investigated in the Gaolan River, which is a tributary of Xiangxi River. Thirty-one algal genera from seven phyla were identified. Results show that the lowest concentrations of total phosphorus （TP） and total nitrogen （TN） were 0.06 mg/L and 1.08 rag/L, respectively. The values of TP and TN exceeded the threshold concentration of the eutrophic state suggested for freshwater bodies. In the Gaolan River, the succession of phytoplankton showed clear seasonal characteristics. Different dominant species were observed among seasons under the control of environment factors. In spring and summer, the dominant species were Nitzschia sp. and Aphanizomenon flos-aquae （L.） Ralfs, the limiting nutrient was NO3^--N, and the key environmental factor for phytoplankton population succession was water temperature （WT）. In autumn and winter, the dominant species were A.flos-aquae and Chlorella sp., the limiting nutrient was pO3--P, and the key environmental factors were transparency and WT. This study illustrates the influence of physical and chemical factors on phytoplankton seasonal succession in a tributary of TGR since the downstream regions of Xiangxi River and Gaolan River became reservoirs after impoundment of the Three Gorges Dam. We suggest that this activity has significantly affected water quality in the dam area.
文摘Though collocations have drawn much attention in the field of language acquisition, difficulties with them have not been investigated in much detail. This paper reports on a corpus-based exploratory study that analyzes the mistakes learners made when they produced English collocations. The current study shows that not only beginners but also advanced learners have difficulties in choosing the right collocates and the difficulties that learners of different levels have are more or less the same. The L1 influence on the production of L2 collocations exists at every stage of learning though it varies with the learners' L2 competence.
文摘Objective: To assess the effects of Tai Chi (Chinese shadow boxing exercise) for improving the lower-limb muscle strength in elderly people. Methods: The PUBMED database (from 1950), EMBASE-ASP database (from 1974), Cochrane Library (from 1991), Elsevier sciences database (from 1990), OVID full text database (from 1997), Springer-link database (from 1997), The National Research Register database, ISI Web of knowledge (from 1963), Chinese Medical Citation Index/Chinese Medical Current Contents (CMCI/CMCC, from 1989), China Knowledge Resource Integrated Database (CNKI, from 1915),VIP database (from 1989), and Wanfang database (from 1977) have been searched only for the English and Chinese literatures updated to 10-30-2010. Two researchers independently assessed the methodological quality of studies, extracted and checked the data one another according to the include/exclude standards. Disagreement was resolved by discussions or with the third person. The Review Manage Software 5.0 was used for Meta-analysis. Results: Eventually, 2 randomized controled studies and 2 non-randomized controled studies met the inclusion criteria, with 163 subjects involved in the present meta-analysis. The meta-analysis demonstrated that Tai Chi exercise could improve the ankle flexor/extensor muscle strength and the knee extensor/flexor muscle strength, tested with an isokinetic dynamometer. The limb muscle strength increased significantly after Tai Chi exercise (P<0.01). Conclusion: The meta-analysis favours Tai Chi exercise for improving the lower-limb muscle strength in the older people.
