中国生猪耗粮系数时空演变特征

当代中国,生猪饲料粮的生产与消费已经逐渐成为影响我国粮食安全保障的重要问题。耗粮系数是合理测算饲料粮需求量的核心,厘清其时空演变特征对准确测算饲料粮数量具有重要意义。通过着重测算2000—2018年中国不同规模饲养生猪耗粮系数,探讨其时空演变特征及可能原因,得到以下主要结论：（1）近年来我国生猪耗粮系数呈现出明显的上升趋势,由2000年的2.39上升至2018年的2.76,年均增长0.023。（2）不同规模饲养生猪耗粮系数的差距逐渐缩小,主要受到饲养过程中使用的精饲料占比变化趋同的影响。（3）大规模饲养生猪的粮食转化效率和时间效率均高于其他规模。（4）散养生猪的耗粮系数在空间上呈现“南北高,中部低”,其他规模则呈现“北高南低,中部高东西低”的格局。从提高粮食利用效率的角度,我国生猪养殖宜继续推动大规模饲养。     

Comparison of macroinvertebrate community structure in urban (Shenzhen City) streams with typical habitat characteristics北大核心CSCD

2020年12月在深圳市城市区域典型生境特征溪流——城市山区源头溪流金龟河、国家地质公园保护区入海溪流杨梅坑河与黑臭水体治理后溪流石溪河,开展底栖动物多样性与生境质量状况取样,通过多元统计分析探明各溪流底栖动物群落结构差异及其主要环境影响因子.结果表明:(1)金龟河底质异质性(SI)最高;杨梅坑河水质最好且流态异质性(Fr)最优,石溪河水质最差且底质异质性(Fr)最低.(2)共采集鉴定大型底栖动物118个分类单元,隶属于3门6纲14目87科.水生昆虫均占绝对优势,其中金龟河67属(81.7%),杨梅坑河62属(95.4%),石溪河12属(52.2%).金龟河中底栖动物Shannon-Wiener多样性指数、改进的Shannon-Wiener多样性指数、Pielou均匀度均高于杨梅坑河与石溪河.(3)金龟河的主要功能摄食类群是滤食者(45.5%),杨梅坑河(38.3%)与石溪河(58.7%)的主要功能摄食类群均为收集者.(4)冗余分析(RDA)结果显示,氨氮、海拔、湿宽、水温、溶氧、底质异质性(SI)、电导率和流态异质性(Fr)为影响深圳市溪流的大型底栖动物群落结构的主要环境因子.研究表明:(1)深圳市的山区溪流可作为深圳市生物多样性保护的重点区域.(2)在城市溪流生态系统中,水环境化学因子并非为主要影响因子,生境多样性发挥了重要作用.(图6表3参43)     

UV-B辐射增强对褶皱臂尾轮虫摄食的影响

运用生态毒理学方法,研究了UV-B辐射条件下褶皱臂尾轮虫(Brachinonus plicatilis)对6株海洋微藻:小球藻(Chlorella sp.、绿色巴夫藻(Pauloua uiridis)、扁藻(Tetraselmis chuii)、球等鞭金藻8701(Isochrysis galbana Park 8701)、牟氏角毛藻(Chaetoceros muelleri Lermumerman)和小新月菱形藻(Nitzschia clostertum)的摄食.结果表明:UV-B辐射增强对褶皱臂尾轮虫的摄食有显著的抑制作用.与对照组相比,褶皱臂尾轮虫对每一种饵料单胞藻的滤水率和摄食率都表现出,随UV-B辐射剂量的增大而显著减小(P＜0.5).而且对每一种饵料单胞藻的滤水率和摄食率是不相同的,这说明褶皱臂尾轮虫对饵料单胞藻是有选择性的.     

Emissions of volatile hydrocarbons from floating roof tanks and their local dispersion: Considerations for normal operation and in case of damage

This work investigates the release and dispersion of volatile organic hydrocarbons, which may escape from external floating roof tanks (EFRT) during normal operation or in case of damage. The dispersion will be described using CFD simulations in close range of the EFRT where hazardous areas are assigned. The aim of this work is to investigate which events can lead to emissions in dangerous quantities and to estimate the corresponding likelihood with regard to explosion protection. An emission in hazardous amount is present if the lower explosion limit has been exceeded and if the extent of this emission is not too low. It is discussed in particular whether the used zoning of potentially explosive areas is conservative or over-conservative.     

环境补偿制度——解决环境问题的经济手段之一

为了保护环境，使环境资源可持续利用，应该建立环境补偿制度。环境补偿制度是解决环境问题的有效手段之一。从环境补偿的概念出发，对环境补偿制度的理论基础进行了探讨，为我国建立环境补偿制度提供依据。     

应用OCMA-220型油分仪测定水样中油含量在实际工作中的几个问题

ＯＣＭＡ－２２０型油分仪应用非散红外光谱法测定水样中油的含量，测定结果较稳定，准确度较高，在环境监测中应用广泛。实际操作中，水样中悬浮料粒子较多且萃取层与ＣＣＬ４层为乳化状态时，必须经滤纸过滤和无水Ｎａ２ＳＯ４脱水处理，才能进行测定。但经滤纸过滤和无水Ｎａ２ＳＯ４脱水处理后，空白值分别在５ｐｐｍ和１６ｐｐｍ以上，如果样品油含量较低时，产生的系统误差，将导致分析结果准确度降低。     

大熊猫人工育幼研究

１９９４年，成都大熊猫繁育研究基地的雌性大熊猫“成成”产下１胎２仔，因母兽病及奶头特大，１仔人工喂养，另１仔由母兽喂养，母兽喂养的１仔仅存活了５７ｈ０３ｍｉｎ人工喂养的１仔存活至今已达２ａ有余，１９９５年，雌性大熊猫“冰冰”又产１胎２仔，其中１仔照１９９４年的方法人工喂养，幼仔生长发育正常，活泼健壮，母兽喂养的仔仅存活了２５ｈ，本文对人工喂养大熊猫初生幼幼存活的饲喂方法，以及幼仔的生长发育规律等进     

Attraction,deterrence or intoxication of bees (Apis mellifera) by plant allelochemicals

The influence of 63 dietary allelochemicals (alkaloids, terpenes, glycosides,etc.) on the feeding behaviour of bees (Apis mellifera) was tested in terms of deterrency and attraction. For 39 compounds a deterrent (mostly alkaloids, coumarins and saponins) and for 3 compounds an attractive response (mostly terpenes) was obtained in choice tests, which allowed the calculation of respective ED₅₀-values. Under no-choice conditions, 17 out of 29 allelochemicals caused mortality at concentrations between 0.003 and 0.6%. Especially toxic were alkaloids, saponins, cardiac glycosides and cyanogenic glycosides. These data show that bees which are confronted with plant allelochemicals in nectar and pollen, are not especially adapted (i.e. insensitive) to the plants' defence chemistry. GLC and GLS-MS data are given on the alkaloid composition of nectar and pollen ofBrugmansia aurea, Atropa belladonna andLupinus polyphyllus.     

邻苯二甲酸二丁酯对大型蚤(Daphnia magna)的毒性作用研究

本研究选用大型蚤(Daphnia magna)作为实验生物,研究了邻苯二甲酸二丁酯(DBP)对其急性毒性作用和慢性毒性作用,同时还研究了环境因素(温度、硬度、腐殖酸)对DBP24h-EC(50)的影响.结果表明DBP对大型蚤的24h-EC_(50)为10.35mg·1~(-1),温度、硬度和腐殖酸对DBP24h-EC_(50)均有一定影响.DBP对大型蚤的捕食行为产生抑制,EC_(50)在 6—7mg·1~(-1)之间.慢性毒性实验结果表明DBP对大型蚤的生长繁殖产生一定影响,低浓度DBP对大型蚤生长繁殖有一定的刺激作用,高浓度DBP对大型蚤生长繁殖存在抑制作用,BDP的最大允许安全浓度为1—2mg·1~(-1).     

To breed or not to breed—food competition and other factors involved in female breeding decisions in the pair-living nocturnal fork-marked lemur (<Emphasis Type="Italic">Phaner furcifer</Emphasis>)

Differential access to food resources is thought to be the main determinant of differences in female reproductive success but is poorly studied in both pair-living and nocturnal primates. The modes of food competition within and between families were investigated following the principles proposed by the ecological model using 3 years of field data from seven fork-marked lemur (Phaner furcifer) families. The major food resources were identified from year-round feeding observations and the strength and mode of competition were inferred from differences in physical condition. The most important food resource of fork-marked lemurs were tree exudates which occurred in small, defendable food patches, characterized by fast depletion and rapid renewal. These characteristics led to strong within-group contest and scramble competition, which were found to yield a positive dominance effect and a negative group-size effect on female net energy gain. Differential physical condition, however, did not translate directly into differential reproductive success. Low female fertility was best predicted by large family size associated with delayed dispersal by previous offspring. Although there is no obvious benefit from full-grown offspring in their territory, adults tolerate delayed natal dispersal, probably because dispersal poses extraordinary costs for the offspring. These costs are likely to accrue from decreased foraging efficiency in unfamiliar habitats because exudate feeding requires very rigid feeding itineraries. In conclusion, the presented evidence for group-size effects on reproductive success in pair-living females opens a new area for research on the costs and benefits of delayed dispersal and female reproductive decisions.This revised version was published in September 2003 with corrections to the Authors Present address.An erratum to this article can be found at Communicated by E.H.M. Sterck