干白葡萄酒增香酿造工艺参数优化

试验以一种酿酒葡萄为原料,利用顶空固相微萃取/气相色谱-质谱联用技术(HS-SPME/GC-MS)检测了不同可同化氮含量(200、300、400 mg/L)、酵母多糖(150、250、350 mg/L)、发酵温度(14、18、22℃)、初始pH值(3.3、3.5、3.7)和SO2添加量(40、70、100 mg/L)处理发酵酒样中的挥发性香气化合物,探讨了复合酿造因子对贵人香干白葡萄酒主要香气物质含量的影响关系。结果表明,300 mg/L的可同化氮有利于高级醇、酯类、单萜化合物的积累;酵母多糖添加量为250 mg/L时,单萜化合物质量分数达到最大值(198.54μg/L);发酵温度从14℃升高到22℃时,高级醇含量显著升高,酯类和单萜含量显著降低;提高葡萄汁初始pH有利于单萜化合物的积累,不利于高级醇、酯类的生成;添加70 mg/L的SO2时,单萜化合物质量分数最高(181.73μg/L)。正交试验极差分析表明,发酵温度和SO2添加量对高级醇含量影响较大;发酵温度与可同化氮对酯类香气物质含量的影响较大,酵母多糖和pH值对单萜类香气物质含量影响较大。各处理组间的聚类分析可知,可同化氮和酵母多糖对主要香气化合物的影响关联度较高、葡萄汁初始pH值和SO2添加量关联度较高。较低的发酵温度有利于酒样中香叶醇、异戊醇、苯乙醇、辛酸乙酯的生成,添加中等浓度的可同化氮和酵母多糖可促进乙酸异戊酯、乙酸己酯和己酸乙酯的合成,较高的初始pH值有利于芳樟醇、香茅醇和香叶醇的积累。综合分析,发酵温度18℃、初始pH值3.5、70 mg/L SO2、300 mg/L可同化氮、250 mg/L酵母多糖酿造贵人香干白葡萄酒,可有效促进酒样中主要香气化合物的合成释放。     

Trends in grain yields and soil organic C in a long‐term fertilization experiment in the China Loess Plateau

Changes in grain yields and soil organic carbon (SOC) from a 26 y dryland fertilization trial in Pingliang, Gansu, China, were recorded. Cumulative C inputs from straw and root and manure for fertilizer treatments were estimated. Mean wheat (Triticum aestivum L.) yields for the 18 y ranged from 1.72 t ha^–1 for the unfertilized plots (CK) to 4.65 t ha^–1 for the plots that received manure (M) annually with inorganic N and P fertilizers (MNP). Corn (Zea mays L.) yields for the 6 y averaged 2.43 and 5.35 t ha^–1 in the same treatments. Yields declined with year except in the CK for wheat. Wheat yields for N only declined with time by 117.8 kg ha^–1 y^–1 that was the highest decrease among all treatments, and that for NP declined by 84.7 kg ha^–1 y^–1, similar to the declines of 77.4 kg ha^–1 y^–1 for the treatment receiving straw and N annually and P every second year (SNP). Likewise, the corn yields declined highly for all treatments, and the declined amounts ranged from 108 to 258 kg ha^–1 y^–1 which was much higher than in wheat. These declined yields were mostly linked to both gradual dry weather and nutrients depletion of the soil. The N only resulted in both P and K deficiency in the soil, and soil N and K negative balances in the NP and MNP were obvious. Soil organic carbon (SOC) in the 0–20 cm soil layer increased with time except in the CK and N treatments, in which SOC remained almost stable. In the MNP and M treatments, 24.7% and 24.0% of the amount of cumulative C input from organic sources remained in the soil as SOC, but 13.7% of the C input from straw and root in the SNP, suggesting manure is more effective in building soil C than straw. Across the 26 y cropping and fertilization, annual soil‐C sequestration rates ranged from 0.014 t C ha^–1 y^–1 for the CK to 0.372 t C ha^–1 y^–1 for the MNP. We found a strong linear relationship (R² = 0.74, p = 0.025) between SOC sequestration and cumulative C input, with C conversion–to–SOC rate of 16.9%, suggesting these dryland soils have not reached an upper limit of C sequestration.     

黄土高原半干旱区保护性耕作适应性评价

在黄土高原半干旱区连续4年保护性耕作试验的基础上,利用层次分析法,对5种保护性耕作法与传统耕作法适应性(生态与经济)进行综合评价,探究适合黄土高原半干旱区的保护性农业技术体系.结果表明:在两种轮作次序(小麦/豌豆、豌豆//小麦)、两种投入方式(计秸秆和不计秸秆)下,保护性耕作法免耕秸秆覆盖(NTS)综合适应性指数(PI)均显著高于其他几种耕作方式,且PI在0.76～0.86之间,是传统耕作法(T)的2～2.5倍,NTS在该地区的适应性最强;NTS、免耕不覆盖(NT)、免耕结合地膜覆盖(NTP)3种耕作方式的PI高于传统耕作结合秸秆还田(TS)、T、传统耕作结合地膜覆盖(TP),说明NTS、NT、NTP在该区的适应性优于TS、T、TP.因此,在黄土高原半干旱区实施保护性耕作措施NTS,更能促进该区农业的持续发展.     

干旱及复水处理下坪用黑麦草和高羊茅抗旱特性比较

本试验以冷季型草坪草高羊茅(Festuca arundinacea)品种凌志（Barlexas）和黑麦草（Lolium perenne）品种首相（Premier）为供试材料,研究其在干旱胁迫和复水过程中的生长、形态指标的变化。结果表明,两种草坪草在干旱胁迫期间叶片相对含水量、叶片水势、蒸散量、土壤相对含水量、草坪质量、生长速率呈明显下降趋势,质膜透性(以相对电导率表示)、萎蔫率呈上升趋势;复水后两草种叶片相对含水量、萎蔫率、叶片水势、生长速率和凌志草坪质量恢复到对照水平,两草种质膜透性、蒸散量和首相草坪质量未恢复到对照水平。胁迫期间凌志各指标可保持较好水平,变化幅度也相对较低,复水期间凌志各指标恢复速度快,复水结束时较多指标恢复到胁迫前水平,说明高羊茅品种凌志的抗旱性及恢复能力优于黑麦草品种首相。     

亚高山草甸类草地退化评估及草地保护对策

为研究亚高山草甸类草地退化及草地保护对策,在实地测定大量样方和统计分析的基础上,选取了盖度、物种多样性指数、丰富度指数、物种数、草地质量指数、优良牧草比例等指标作为评估指标,制定了亚高山草甸类草地生态质量评估的4级指标值。选择各级别典型生态区域,对其现状和指标值进行了对比分析。结果表明,该方法反映了植被生态的量化指标,各项指标相互联系和相关,具有易获得性和实用性,符合当地生态质量现状,可以科学、客观地评估区域生态质量。超载过牧,滥采乱挖,人为破坏,生物链失衡等是造成生态退化的人为因素。控制放牧,防止滥采乱挖,建立自然生态保护区是维护该区域生态系统平衡的措施。     

干制黄花菜工业化生产工艺技术

为改进干制黄花菜传统生产方法并实现工业化生产,采用带式汽蒸生产线对黄花菜进行前处理,在干制过程中将全自动隧道式干燥生产线与工业微波生产线相结合,利用正交试验设计对干制黄花菜工业化生产工艺技术条件进行了较为详尽的研究。结果表明,在蒸汽温度95℃,汽蒸时间60s;隧道式干燥生产线装载量5.0kg/m2,热风温度85℃,风速1.5m/s;微波干燥生产线铺料厚度15mm、干燥功率16kW、干制时间90s的条件下,所生产的干制黄花菜经农业部食品质量监督检验测试中心检测其感官、理化和微生物指标均达到了《无公害食品—干制金针菜》NY5186-2002所规定的一级品标准。     

黄河首曲重大生态功能区护岸林建设问题探讨

分析了河岸防护林改变区域小气候、巩固河岸、保持水土、防风固沙、改良土壤、湿地保护、提供饲料、薪材和增加收入、提高畜牧业生产力、丰富和改善高寒区景观等作用,系统阐述了加强河岸防护林建设的重要性,针对性地提出了河岸防护林树种组成单一、体系结构不够完整、自然因素恶劣等护岸林建设问题,并提出了进一步发展建设的对策,在黄河首曲重大生态功能区的环境建设中加强黄河护岸林建设,对于黄河首曲生态环境的治理、恢复、重建和改善具有十分重要的意义。     

计算机学科中数据处理的一般过程——以线性表处理为例

本文主要以线性表为实例,讨论了在计算机学科中数据处理的三个一般过程,即分析和提炼数据结构和数据关系;依据数据结构和数据关系,找出正确处理数据的方法;在计算机上实现数据的正确处理。     

Relationships between farm characteristics and the variation of the density of hedgerows at the level of a micro-region of bocage landscape. Study case in Brittany,France

In a perspective of managing the evolution of the bocage landscape, we address the issue of the joint development of agriculture and landscape at micro-regional scales. The study aims at testing the hypothesis of a relationship between bocage structure and farm characteristics along a 10-km long gradient of decreasing density of hedgerows in Brittany (France). A sample of 69 farms is made from three study sites chosen along this gradient. Dairy production with maize, cereals and grassland predominate. Farm territories are scattered along the gradient. The production, economic levels, productivity and technical means increase from the dense to the open bocage area. There is a joint significant differentiation of the technical systems. Different levels of organization of the farming systems thus contribute to this pattern. The results suggest that the nature and organization of this joint diversity are key factors to evaluate and manage future developments.