葡萄酒香气成分的仪器分析方法评述

葡萄酒香气成分的研究对葡萄酒产品的质量评价及葡萄酒产品的真伪鉴别意义重大,而香气成分的分析结果及其区分价值取决于分析方法,尤其是香气成分的萃取方法。文章综述了近几年葡萄酒香气成分分析方法的研究进展,分析了"电子鼻"等非色谱方法分析葡萄酒香气的特点,阐述了葡萄酒香气成分气相色谱分析的不同检测器方法,比较了影响葡萄酒香气色谱分析结果的不同香气成分萃取方法,并对今后该领域的研究重点进行了展望。     

北京市生态安全格局保护紧迫性分级

以北京市为例,通过粒度反推法和景观连通性识别重要生态用地,通过邻域分析法构建生态阻力面,采用MCR模型构建北京生态安全格局,利用人工神经网络计算建设用地扩张概率,对构建的生态安全格局进行保护紧迫性分级。结果表明,北京市重要生态用地面积为6488.53 km²,主要分布在西部和东北部山区,小部分位于东南平原。一级生态用地面积为4482.48 km²,主要分布在西北和西南地区;二级生态用地面积为1338.27 km²,主要分布在西部远郊山区、西南部近郊平原和东南部平原;三级生态用地面积为669.77 km²,主要分布在中北部和东南部平原。重要生态廊道长度为2410.47 km,分布在远郊城镇以及城乡交界处。一级生态廊道长度为1477.63 km,主要分布在西北和西南远郊山区;二级生态廊道长度为390.91 km,主要分布在远郊平原的生态用地附近;三级生态廊道长度为541.93 km,主要分布在城市中心的周边地区,呈环状包围中心城区。     

Characteristic investigation of trilayered Cu/Al8011/Al1060 composite: Interface morphology,microstructure, and in-situ tensile deformation

In this work, Cu/Al8011/Al1060 trilayered composite with an ultrathin copper layer was fabricated successfully by the hybrid process of cast-rolling and hot-roll-bonding. The effects of heat treatment were investigated on the microstructure and mechanical behavior of the composite. The results showed that annealing temperatures above 300°C led to the formation of new intermetallic compounds that joined their initial counterparts. Also, the interface growth was fast above 340°C. It was found that...     

多节挤扩支盘灌注桩在高层建筑中的应用

分析了支盘的受力特点及多节挤扩支盘桩在成桩过程中的影响因素、施工要点,并对比其经济价值.结合工程实例,介绍了在高层建筑的桩基施工中采用多节挤扩支盘灌注桩的施工技术.     

基于蒙特卡洛法的硅纳米线热导率研究

声子在纳米尺度下的输运需要考虑量子效应与边界效应,通过解析方法获得其传输特性比较困难,采用蒙特卡洛方法(Monte Carlo,MC)构建了声子在体态硅与硅纳米线结构中的输运模型,简化了边界散射的选择机制与处理方法.在15～1 000 K的温度范围内,对体态硅的热导率进行了模拟,验证了MC模型对本征散射处理方法的正确性,进而模拟了等效直径为22,37与56 nm的硅纳米线在15～315 K温度范围内的热导率,37和56 nm硅纳米线热导率与实验值符合较好,22 nm硅纳米线热导率比实验值偏大.分析认为随着等效半径的减小,声子色散曲线发生改变,迟豫时间减小,声子发生边界散射的频率增加,导致热阻增大.基于以上分析,通过对边界散射迟豫时间的修正,获得了与实验值较为一致的模拟结果.     

一种新的快速FPGA布局算法

在模拟退火算法的基础上,提出了一种快速FPGA布局算法.该算法先用解析模型快速确定所有宏模块及单个逻辑模块的"理想"位置,然后通过局部扩散消除模块之间的重叠,得到一个较好的初始布局方案,最后再用低温的模拟退火进一步优化,确定各模块的最终位置.实验数据表明,以目前在学术界普遍采用的平方线网总长度为目标函数,与经典的VPR算法相比,新算法大大降低了布局所耗费的时间,而不影响最终布局方案的质量.     

太湖实测水温多时间尺度变化特征及影响因素

水温是评估湖泊生态系统状态、功能和过程的重要参数,在多时间尺度上影响着湖泊的物理、化学、生物和生态过程.基于太湖中尺度通量网避风港站点2012—2016年的水温梯度、小气候和辐射四分量的观测数据,分析了太湖水温在不同时间尺度上的变化特征,选取夏季高温和冬季冷空气过境个例分析太湖水温对天气条件变化的响应,并量化了太湖水温...     

Effects of metals and organic compounds on survival and bioaccumulation in two species of marine gammaridean amphipod,together with a summary of toxicological research on this group

The toxicity and bioaccumulation of arsenic, cadmium, copper, lead, mercury, zinc, DDT, PCB and the water-soluble fraction of diesel fuel to the gammaridean amphipods Corophium insidiosum and Elasmopus bampo were measured. At 96 h exposure C. insidiosum was more sensitive to arsenic, zinc, DDT, PCB and the water-soluble fraction of diesel fuel than E. bampo, whereas E. bampo was more sensitive to cadmium, chromium and copper than C. insidiosum. Over a 20-day period C. insidiosum accumulated greater amounts of chromium, copper, lead and zinc than E. bampo, whereas E. bampo accumulated more cadmium, DDT and PCB than C. insidiosum. The toxicity and bioaccumulation of toxicants to other species of marine gammaridean amphipods are tabulated.     

Net-shape forming of composite packages with high thermal conductivity

The continuing miniaturization of electronic devices in microelectronics and semiconductors drives the development of new packaging materials with enhanced thermal conductivity to dissipate the heat generated in electronic packages.In recent years,several promising composite materials with high thermal conductivity have been developed successfully for high performance electronic equipment to replace the traditional Kovar and Cu/W or Cu/Mo alloys,such as SiCp/Al,SICp/Cu,diamond/Al and diamond/Cu.However,thes...     

Genetic and morphometric variation of the Blackcap (Sylvia atricapilla) on the Azores Archipelago reveals a recent range expansion

ABSTRACT

The Blackcap, Sylvia atricapilla, is one of the few passerine species that breeds in all the Macaronesian archipelagos. The sedentary habits of these populations contrast with the migratory populations from the Western Europe. However, little is known for Azorean populations. We assessed the phylogeography of populations from the Azores based on sequences of two mitochondrial genes and one nuclear gene in the Z-chromosome. We also analysed differences in eight morphometric characters from a total of 282 Blackcaps from all the Azores islands. Our results suggest the occurrence of historical and/or current gene flow among birds from all the islands. Blackcaps from the Azores are close relatives of those from Madeira and Portugal, indicating a recent range expansion to the Azores in the last 0.1 million years. The analysis of morphometric data showed a high morphological diversity among and within the islands, probably related to ecological traits.