世界水产品绿色养殖比较研究及对中国启示

当前全球渔业捕捞量已接近顶峰局势,水产养殖发展面临巨大环境压力,水产品绿色养殖能满足消费者对优质蛋白需求的同时,还能有效缓解生态问题,保证食品质量安全。水产品养殖绿色发展已成为世界各国的共识,渔业发达国家在一定程度上已形成较完善的绿色水产养殖体系。文章基于全球水产业发展现状和趋势,通过研究欧盟、美国和日本水产品绿色养殖的相关经验,最后结合中国水产养殖业发展现状,提出在建立严格认证标准的基础上,国内政府应加强对“绿色水产品”消费的正确引导;借鉴别国对渔业可持续发展的政策和管理制度;注重关键科学技术的研发,做到产学结合;保障资金的有效投入等相关政策建议。     

"4D"数据在生态环境监测与评价中的应用

本文在阐述由DLG、DRG、DEM和DOM组成的4D产品的信息特征的基础上,深入分析了"4D"数据在生态环境监测与评价中的功能,包括生态环境的快速动态监测、三维生态景观的直观分析和表达、DLM与DCM相结合的生态模拟、多时空尺度的生态环境分析与评价等.并以云南省生态环境监测与评价为例,研究了其在生态环境监测与评价中的技术流程,并通过案例分析,生成了系列生态环境地图.     

使用MODIS陆地产品LST和NDVI监测中国中、西部干旱

利用中分辨率成像光谱仪AQUA-MODIS卫星资料反演的地表温度LST和归一化差值植被指数NDVI,在中国中、西部地区应用植被温度混合状态指数VTCI方法,遥感监测干旱的空间分布状况。同时结合该地区有代表性的气象站逐月降水资料与VTCI指数进行相关分析,来验证此方法的适用性。结果表明,VTCI指数不仅与当月的降水量,也与其前期2至6个月的累积降水量有较好的线性相关性,显示VTCI方法不仅是较为有效的近实时大范围干旱监测方法,对于干旱的缓慢发展过程也有一定指示作用。     

动机、成本、风险：家长视角下研学旅游产品价值感知研究

以中小学生自然教育研学旅游作为具体情境,基于539份家长问卷数据阐释研学旅游动机与价值感知之间的关系,并通过成本感知和风险感知探讨其内在机制和边界条件。结果表明,家长感知的研学旅游动机越强烈,越容易感知到研学旅游产品所传递的价值,验证了研学旅游情境下动机对价值感知的积极影响,也形成了对动机与价值之间关系研究的理论补充。并且,这一动机除了直接作用于价值感知外,还会通过成本感知的部分中介作用影响价值感知,揭示了中国家长对于教育价值的重视会削弱其对“利失”的感知。此外,进一步验证了风险感知的积极影响,即家长感知研学旅游的不确定性水平越高,动机对价值感知的积极影响越明显,且会抑制成本感知对价值感知的负向作用,但风险感知水平达到一定高度时,其对成本感知与价值感知间的抑制作用将不显著。因此,面向需求设计打造产品,突出产品价值、加大宣传营销力度、把控活动安全、合理制定价格,获取家长群体的认同接受,将是研学旅游进一步拓展市场的重要考量。     

国家气象中心数值预报业务的进展

在最近的１５年中，国家气象中心的数值预报业务高速度发展，预报模式从北半球模式发展为全球谱模式，并配套建立了资料同化系统和用于降水预报的有限区预报模式，暴雨和台风预报模式正在研制中。目前数值预报时效已延至７天，Ｔ６３９３丙上时的预报水平已优于的数值预报产品的应用技术在不断改进，最高（低）气温下两天ＭＯＳ预报精度已接近预报员制作的综合预报结果。     

Intermediate and deep earthquakes in Spain

Recent improvements in the seismological networks on the Ibero-Maghrebian region have permitted estimation of hypocentral location and focal mechanisms for earthquakes which occurred at South Spain, Alboran Sea and northern Morocco of deep and intermediate depth, with magnitudes between 3.5 and 4.5. Intermediate depth shocks, range from 60 to 100 km, with greater concentration located between Granada and Málaga. Fault-plane solutions of 5 intermediate shocks have been determined; they present a vertical plane in NE-SW or E-W direction. Seismic moments of about 10¹⁵ Nm and dimensions of about 1 km have been determined from digital records of Spanish stations.P-wave forms are complex. This may be explained by the crustal structure near the station, discontinuities in the upper mantle and inhomogeneities near the source. Deep activity at about 650 km has only 3 shocks since 1954 (1954, 1973, 1990). Shocks are located at a very small region. Fault-plane solutions show a consistent direction of the pressure axis dipping 45° in E direction. For the 1990 shock seismic moment is 10¹⁶ Nm and dimensions 2.6 km. TheP-waves are of simpler form with a single pulse. The intermediate and deep activities are not connected and no activity has been detected between 100 and 650 km. The intermediate shocks may be explained in terms of a recent subduction from Africa under Iberia in SE direction. The very deep activity must be related to a sunk detached block of lithospheric material still sufficiently cold and rigid to generate earthquakes.     

Multifacetted study of a cretaceous coal with algal affinities—II. Composition of liquefaction products

Two hydrogen-rich lithobodies of highly alipathic character from a coal occurring in southwest Utah, have been studied. Bituminite (>50%), vitrinite (25–30%) and liptodetrinite (7–12%) are the principal macerals. The hexane-soluble products of hydrogenating the lithotypes at 400° with tetralin and hydrogen have been analyzed by GC-MS. Products identified include homologous series of alkylated naphthalenes, phenols, furans, cyclohexenones and hydroxy-pyridines. In the case of furans, the alkyl groups extend beyond C₃₀. Materials released by Soxhlet extraction with pyridine consist chiefly of homologous series of fatty acids and their methyl esters and of methyl alkyl ketones, which were not found in the hydrogenation products. The long alkyl chains in these substances can account for about 75% of the alkanes found in the hydrogenation products but not in the extracts. Most of the compounds mentioned in the foregoing are thought to be physically held or trapped in the coal, rather than chemically combined in its macromolecular network. Except for the fatty acids, the origins of these substances are difficult to identify.     

Pyrolysis of immature Torbanite and of the resistant biopolymer (PRB A) isolated from extant alga Botryococcus braunii. Mechanism of formation and structure of torbanite

Immature Torbanite and the resistant biopolymer (PRB A) isolated from extant B. braunii were previously compared using bulk spectroscopic methods. In the present work, analysis of 400°C pyrolysis products and pyrolysis residues provided further information on their structure and possible relationships. It appears that such polymers are based upon unbranched, saturated, cross-linked hydrocarbon chains up to C₃₁. In addition to these bridging structures, a substantial part of the alkyl chains is singly bound, as esters of unbranched, saturated or cis unsaturated, even fatty acids. These esters are sterically protected, against chemical degradations, by the network of the bioand geopolymer.Quantitative and qualitative observations derived from 400°C pyrolysis confirm that the chemical structure of PRB A and immature Torbanite are closely related. The pyrolysis residues show a similar evolution and numerous common features are noted, with respect to the nature and the distribution of the major constituents of the pyrolysates (hydrocarbons and fatty acids). Accordingly, Botryococcus provides what seems to be the first example of a close structural relationship between a biopolymer produced in large amounts by an extant alga and the geopolymer of an immature kerogen. The essential role of PRB A in Torbanite formation is ascertained. Moreover, it is found that the resistant biopolymer does not undergo important structural changes during the first stages of diagenesis. Thus, owing to steric protection, the esters of immature Torbanite show a distribution quite close to the one of PRB A esters, with exclusively even constituents and a large contribution of unsaturated acids.Recent observations pointed to the possible genesis of some algal kerogens principally by selective preservation of resistant macromolecules. Such a type of formation is clearly predominant in Torbanite, where the bulk of the fossil organic matter corresponds to a selectively preserved and weakly altered, resistant biopolymer, while incorporation of lipids into the kerogen structure during diagenesis seems to play a minor role.     

地球数字产品的空间数学基础

在分析当前地球数字产品空间数学基础局限性的基础上,将地图投影概念由传统的曲面到平面的变换扩展为曲面到曲面的变换,提出一套适合于大型GIS和地球数字产品的“地图投影”模型的实用模型,该模型的视图采用等距离切圆柱投影,度量空间是椭球面几何系统,符合计算机环境下GIS视图与度量空间分离的特性。鉴于全球多分辨率连续可视化,精密可视化量算,三维、多维地球数据统一,标准的空间定位框架和只有在统一的空间系统内全球资源、生态环境数据才能进行精确的地理分析等四个方面的需要,从地图投影进到本模型将是方向和技术趋势。