我国城市边缘区发展阶段划分研究

城市边缘区是城市研究中的热点之一。该文在阐述了阶段划分方法论的意义及其对边缘区研究的必要性的基础上,提出了1949年以来我国城市边缘区发展阶段的划分方案,将整个发展过程划分为6个阶段,并分别阐述了各个阶段的发展特征。     

单胃动物消化道内源氨基酸排泄量测定方法学研究进展

综述迄今所提出的内源氨基酸排泄量测定方法的基本原理及其优缺点。并将这些方法划分为３类,第１类是非正常生理条件下的测定方法,包括绝食法（ＦＡＳ）、无氮日粮（ＮＦＤ）法、ＮＦＤ＋合成氨基酸（ＡＡｓ）、ＮＦＤ＋静脉注射ＡＡｓ以及回归法（ＲＥＧ）;第２类是接近生理条件下的测定方法,包括同位素标记内源氮法、同位素标记外源氮法、静脉１次注射小剂量［３Ｈ］Ｌｅｕ法、胍基化蛋白法、酶解酪蛋白／超滤法;第３类是体外／体内消化率差值法。     

齿轮箱传动在泵站中应用分析与选择方法

对齿轮箱传动在国内外低扬程泵站工程中的应用情况进行了综述和初步分析，提出的不同类型的齿轮箱可运用于不同功能和规模的泵站。根据低扬程泵站工程的特点，提出了选用齿轮箱传动的可靠性、高效性、经济性和运行维护便利性等基本原则，并参照国外的经验提出了齿轮箱选择的方法，可供泵站设计时参考。     

~(60)Coγ射线诱变阿维拉霉素筛选高产菌株及培养基优化

用60Coγ射线对绿色产色链霉菌A-05菌株进行了诱变处理,以正突变率为标准确定诱变的适宜剂量为350 Gy。诱变后得到5株较高产突变菌株,其中H-15菌株经连续传代6次,遗传性状稳定,阿维拉霉素发酵单位达到68.5mg/L。采用响应面分析法对菌株H-15生产阿维拉霉素的发酵培养基碳氮源进行了优化设计。在所试验的碳氮源中,可溶性淀粉、核糖分别作为唯一碳源时,阿维拉霉素发酵单位较高,分别达82.67和79.45mg/L,乳糖、果糖、葡萄糖分别作为唯一碳源时菌株的效价较低;3%的豆粕粉和2%的大豆蛋白胨作为氮源时阿维拉霉素发酵单位分别为77.6和62.7mg/L。采用双碳源双氮源更有利于菌株提高阿维拉霉素的发酵单位,响应面分析结果表明,可溶性淀粉、核糖和大豆蛋白胨对阿维拉霉素发酵单位影响较显著。优化后的碳氮源组成为:可溶性淀粉20.12g/L,D-核糖7.81g/L,豆粕粉25.23g/L,大豆蛋白胨5.06g/L。优化后的模型计算出阿维拉霉素发酵单位由原来的71.63mg/L提高到101.48mg/L。     

论农学研究的发展

较为详细地论述了中国传统农学和西方近代农学的哲学基础、方法论及它们各自的不足。中国传统农学思想的阐释借鉴了中国古代哲学的概念和范畴,以朴素的系统、整体观察为特征。西方近代农学则以还原论为基础,以实验、分析方法为特征。系统科学是20世纪兴起的联系社会科学与自然科学的一门横断性学科,是探索整体、演化及其复杂性的科学。现代农学研究应引入系统科学的哲理观和方法论,对于融合中国传统农学与西方近代农学、发展现代农学有重要意义。     

On the relationship between feminism and farm women

Much international research haspointed out that farm women in a Westernagricultural context have not identified withthe ideas and politics of feminism. This issuehas troubled feminist scholars in the field,since much research has documented thesubordinate position of farm women. However,concerning the question of why farm women have notadopted feminism, assumptions ofprogress can be read: gender equality and emancipationof women will eventually take place once theagricultural sector has reached a higher stageof development; concerning universalism: thereexists a common women's identity and experienceof male oppression that forms the basis foridentity politics. The question may beidentified as a researcher question embeddedwithin the assumptions of the feminist researchcommunity, which struggles with establishing asubject-subject relationship between theresearcher and the researched. As such, it is thebasis for the production of partial, situatedknowledge and must be recognized as such.     

Technique for normalizing intensity histograms of images when the approximate size of the target is known: Detection of feces on apples using fluorescence imaging

A challenge in machine vision is to develop algorithms for detecting a substance with an amorphous shape when measured responses of both the substance and the underlying target have similar characteristics. The challenge is exacerbated when responses for targets are highly variable both across and within discrete target units. An example of this problem is the detection of fecal contamination on apples. Feces on apples can be detected using differential fluorescence responses of contaminated and uncontaminated apple surfaces to UV excitation. However, responses of both feces and apples are due to the presence of chlorophyll-related compounds, and the response of apples varies within and between apples due to natural variation in the distribution of these compounds. We present a technique for normalizing the variability of intensity responses among targets based on a priori knowledge of the image dimensions and the approximate target size. Using this information, a linear equation is derived based on the approximate median intensities of the background and of the target. The median intensities are estimated by calculating a cumulative intensity histogram and using a priori estimates of the percentage of the area in the image occupied by the background and by a generic target. The image is scaled for uniform intensity power using this linear transformation. The benefits of using this technique are demonstrated using hyperspectral fluorescence responses to UV excitation of 48 Golden Delicious and 48 Red Delicious apples artificially contaminated with dilutions of cow feces. Results show that the uniform power transformation normalizes the intensity distributions of apple images and increases the contrast between contaminated and uncontaminated areas on apple surfaces; the coefficients of variation for the average intensities of uncontaminated apple surfaces at 668 nm for Golden and Red Delicious apples were reduced from 39 and 55%, respectively, to 5% for both varieties.     

Extractable and dissolved soil organic nitrogen - A quantitative assessment

Extractable Organic N (EON) or Dissolved Organic Nitrogen (DON) pools are often analyzed to predict N mineralisation, N leaching, and to evaluate agricultural (nutrient) management practices. Size and characteristics of both pools, however, are strongly influenced by methodology. Quantifying the influence of methodology can increase the accuracy of soil tests to predict N mineralisation, improve model simulations, and can help to quantify the contribution of the EON and DON pools to soil N cycling. We estimated the relative impact of methodological, management, and environmental factors on EON and DON, using a meta-analysis approach based on 127 studies. Our results indicate that the EON and DON pools are neither similar in size nor controlled by the same factors. The influence of factors controlling EON generally decreased in the order of methodology (Δ10-2400%), followed by environment (Δ11-270%) and management (Δ16-77%). DON concentrations were primarily controlled by management factors: different land use and fertilisation caused a variation of 37-118%. Seasonal variations in DON concentrations were generally smaller than variations in EON, suggesting that high mineralisation and sorption rates buffer DON. The large range in EON as affected by different methodology emphasizes the importance of using appropriate and standardized methods for the determination of EON. The determination of DON can be useful to estimate leaching losses. EON, however, can be used to assess the impact of soil management practices on the turnover rate of labile soil organic matter pools.     

Application of Box-Behnken Design for Optimization of Different Pretreatment Conditions for Cellulase Production

Effects of dilute acid and acid steam pretreatments were inspected for cellulose production of Eucalyptus leaves through Box-Behenken design,a three variable factors for response surface methodology by Bacillus subtilus K~(-1)8.Maximum cellulose production performed in 250 mL erlenmeyer flask with submerged fermentation attained at 50℃,p H 5,140 r·min~(-1) for 24 h.Results showed the efficient cellulose production from acid steam pretreatment(being autoclaved at 15 Psi for 15 min)than acid pretreatment.The optimum condition for maximum carboxymethyl cellulas(CMCase)was 1.811 IU·mL~(-1)·min~(-1)(0.8%acid conc.,10 g biomass loading,6 h reaction time)and filter paper activity(FPase)was 2.255 IU·mL~(-1)·min~(-1)(1%acid conc.,10 g biomass loading,8 h reaction time).Whereas,the acid steam maximum CMCase activity recorded was 2.585 IU·mL~(-1)·min~(-1)(0.8%acid conc.,15 g substrate loading and 8 h reaction time)and the highest FPase activity was 2.055 IU·mL~(-1)·min~(-1)(0.8%conc.,10 g biomass,6 h reaction time then autoclaved).Results revealed that acid pretreated Eucalyptus leaves were better lignocellulosic biomass for cellulose production by submerged fermentation.     

持久性有机污染物的根际修复及其研究方法

根际是具有特殊性质的土壤微生态环境,对土壤中持久性有机污染物的行为及生物修复具有重要作用。本文从微生物降解、植物过程、非生物降解、土壤吸附、挥发、淋溶等方面归纳了有机污染物根际修复的研究进展,并从细胞培养、添加根系分泌物或根系残留物、挥发污染物收集和残留态污染物测定等方面综述了有机污染物根际行为的研究方法及其优缺点。