国内外农村住宅建设比较

农村住宅建设是新农村建设的重要组成部分，在农村经济、社会、生态和文化发展等方面发挥着重要作用。从生态住宅建设角度出发，借鉴国外农村住宅建设经验，依据我国农村住宅建设现状，通过国内外农村住宅建设对比分析，总结国外农村生态住宅建设对我国的启示。      

Effects of Culture Area,Stocking Density,and Shrimp and Fish Polyculture on the Cost Efficiency of Hard Clam,Meretrix meretrix,Culture: A Case Study of Hard Clam Farms in Yunlin,Taiwan

Using the hard clam farms in Yunlin, Taiwan as examples, this study analyzes the effects of culture area, stocking density, and shrimp and fish polyculture on the cost efficiency (CE) of hard clam farming. A data envelopment analysis (DEA) is used to estimate the farms' technical efficiency (TE), allocative efficiency (AE), and CE values. The findings show that the mean TE, AE, and CE values of hard clam farms are 0.74, 0.57, and 0.43, respectively. The TE value is higher than the AE value, which indicates that cost inefficiency is mainly attributable to poor AE. Tobit regression results suggest that there are positive relationships between CE and both culture area and operator experience. Hard clam stocking density and age of the operators have negative effects on CE. Hard clam culture areas larger than 2 ha and a stocking density of 1.1–1.2 million hard clams per hectare have higher CEs than smaller culture areas and smaller or larger stocking densities. The use of sand shrimp, white shrimp, kuruma shrimp, and grass shrimp for polyculture and the use of milkfish and silver sea bream for polyculture are both associated with high CEs.     

红皮云杉嫩枝扦插繁殖技术的研究

本文描述了红皮云杉嫩枝扦插繁殖技术。通过试验筛选出１种适合于红皮云杉嫩枝扦插的基质（插壤），２种使生根率达９８％且根系发育良好的生根剂。同时，提出了把握扦播时机，合理运用生根剂浓度及处理时间的方法和技术措施。     

Perspectives of disease threat in large-scale Pinus radiata monoculture - the New Zealand experience

Large scale P. radiata monoculture has been in existence in New Zealand for over 60 years. During this time a number of damaging diseases (e. g. Sirex-Amylostereum, Dothistroma, Armillaria, Cydaneusma needle cast. Sphaeropsis die-back etc.) have occurred but the impact was by no means devastating as these diseases are either controllable or in some the losses were deemed acceptable. As a large proportion of the biomass produced before age 10–12 is waste-thinned, the acceptable level of disease loss is thereby very high. The practice of clear felling and short rotation reduces some of the disease risks common in other forest systems. Outlook for future disease threat is discussed with respect to current trends toward clonal forestry and the possible arrival of additional exotic pathogens.     

农业机械化工程研究生创新能力的研究

研究生教育作为我国教育结构中的高层次的教育,有责任而且有义务为国家培养高水平、高素质,且具备高层次创新能力的人才,教育体系应加强创新教育,逐步提高研究生的创新能力.在了解了农业机械化工程学科现状与进展后,提出了农业机械化工程学科研究生创新能力培养的建议:进行创新性学习,提高创新意识和创新思维;学校改进教学课程体系;多参...     

秈粳稻杂交育种研究

作者研究了秈粳杂种的生育特性及结实性等经济性状的遗传变异,认为以出穗期为主要指标进行选择,结合其他性状的变异动态,逐步确立优良系统,有助于提高选择的效率,和建立较为合理的杂交育种程序与方法。     

A cell-based screening identifies compounds from the stem of Momordica charantia that overcome insulin resistance and activate AMP-activated protein kinase

Treatment of insulin resistance is a critical strategy in the prevention and management of type 2 diabetes. The crude extracts from all parts of Momordica charantia L. have been reported by many studies for the effective treatment of diabetes and related complications. However, the exact ingredients responsible for the hypoglycemic effect and the underlying mechanism of their actions have not been well characterized because of the lack of a proper assay and screening system. A new cell-based, nonradioactive, and nonfluorescent screening method was demonstrated in this study to screen for natural products from the stem of M. charantia, aiming to identify hypoglycemic components that can overcome cellular insulin resistance. The results suggest triterpenoids being potential hypoglycemic components of the plant and the mechanism underlying their action involving AMP-activated protein kinase.     

Quantifying growth in maricultured corals using photogrammetry

In coral mariculture, growth is one of the most common ways to track success. However, numerous methods of monitoring coral growth make comparative studies challenging. A literature review of 39 studies from 1982 to 2017 indicated that the most predominant non‐invasive methods used were linear and areal measurement and these were evaluated for their accuracy using nursery‐reared corals. The monthly change in linear and areal growth rates of six coral species (n = 215), Pocillopora acuta, Hydnophora rigida, Merulina ampliata, Podabacia crustacea, Echinopora lamellosa and Platygyra sinensis were measured via photogrammetry. We tested whether the planar area of coral colonies can be estimated using three geometric formulas of linear measurements. Based on the literature review, the six types of measurement methods were namely linear, volume, weight, area, count of polyps/branches and calcification, in decreasing order of application. Our results showed that the change in area calculated by geometric mean diameter (GMD) formulas provided the most accurate estimation among the three formulas and was strongly correlated with planar area (R² ≥ .60; p < .05) for all coral species, except E. lamellosa and Pl. sinensis. However, our findings suggest that it is not ideal to use geometric formulas to estimate the change in area. Instead, we posit that areal photogrammetry represents the simplest yet accurate non‐invasive method for rapid monitoring of extensive areas of corals in situ. Lastly, we discuss the recommendations and limitations for areal photogrammetry.     

Effects of dietary docosahexaenoic acid sources,microalgae meal and oil,on growth,fatty acid composition and docosahexaenoic acid retention of orange‐spotted grouper,Epinephelus coioides

This study evaluated the effects of Aurantiochytrium spp. microalgae meal and oil as dietary docosahexaenoic acid (DHA) sources on the growth, fatty acid composition and DHA retention of orange‐spotted grouper, Epinephelus coioides. Dietary fish oil was replaced with microalgae meal or oil to provide an equal amount of DHA as a fish oil‐containing basal diet. In total, three experimental diets were fed to triplicate groups of fish (initial wt: 8.48 ± 0.06 g) in a recirculating system for 8 weeks. The weight gain and feed efficiency of the fish did not differ significantly among the experimental diets. The fatty acid composition of the whole body of the fish generally reflected the composition of their diet. The concentration of eicosapentaenoic acid in the whole body was higher in the fish fed the fish meal control diet than in those fed the two experimental diets The fish fed the control diet and those fed the diet containing microalgae oil exhibited higher DHA concentrations than did the fish fed the diet containing microalgae meal. The whole‐body DHA retention was the highest in the fish fed the diet with microalgae oil, followed by the fish fed the control diet. The lowest whole‐body DHA retention was observed in the fish fed the diet containing microalgae meal. The results suggested that the oil from Aurantiochytrium spp. microalgae can be used as DHA source for the grouper. DHA utilization by the fish was higher when the diet was supplemented with microalgae oil than with dry microalgae meal.     

现代居住区绿化景观设计基本原则

现代居民区生态景观营造越来越受人们关注。文章阐述了居住区绿化的构成要素、发展趋势及基本原则,可供居住区园林设计者参考。