山西省地质博物馆园林景观设计

当前博物馆外部空间景观设计越来越被重视,功能也越来越多样化。阐述山西省地质博物馆的园林景观设计,该设计始终围绕"地质传说"这一设计主题,运用现代材料和艺术手法通过景观构造再现,使人们从中感知地质文化,并形成集休闲、娱乐、教育等功能为一体的城市公共绿地。希望为国内博物馆的园林景观设计提供借鉴。     

河北邯郸市城市广场景观设计初探

分析城市广场建设的必要性,总结邯郸市城市广场建设现状,提出城市广场设计要以人为本、合理规划、突出主题。     

广州城市公园理水特色浅析

分析城市公园理水手法及设计趋势,选取广州城市公园中理水设计具有特色的公园作为案例赏析,归纳总结出城市公园理水特点和设计发展趋势。     

The optimal stability `window': a mechanism underlying decadal fluctuations in North Pacific salmon stocks?

While recent evidence suggests that North Pacific salmon stocks are influenced by decadal variability in atmospheric forcing of the ocean, the actual combination of physical and biological processes that determines this linkage has not been identified. This paper describes a possible scenario in which water column stability is the primary factor by which the physical environment influences phytoplankton production, the basis for production at higher trophic levels. Variation in the strength of the wintertime Aleutian Low pressure area affects water column stabilities, hence primary production, along the entire eastern boundary of the North Pacific. The `optimal stability window' explains the qualitative relationship between fish stocks and the strength of the winter Aleutian Low, as well as the observed out-of-phase variation between northern and southern salmon stocks.     

Determinism of the induction of the reproductive cycle in female Eurasian perch, Perca fluviatilis: Identification of environmental cues and permissive factors

In Eurasian perch, Perca fluviatilis, gametogenesis is induced by decrease of both temperature and photoperiod. However, a multiplicity of other factors can display non-permissive or modulating effects on the induction of the reproductive cycle. Consequently, a 9-week study was carried out to determine the environmental cues and permissive factors controlling the induction of the reproductive cycle in this species. A two-level fractional factorial design 2^8-4 was used in order to identify the influent factors from 8 environmental and nutritional ones and their 28 interactions. Tested factors were: (1) amplitude of temperature decrease, (2) time, (3) kinetics and (4) amplitude of photoperiod decrease, (5) initial nutritional state, (6) handling, (7) feeding rate and (8) light spectrum. Increase of gonadosomatic index (GSIi), proportion of female in exogenous vitellogenesis (EVP), plasma 17 β-estradiol (E₂) and cortisol levels, fat consumption and food intake were evaluated.This study showed that the amplitude of the decrease of temperature and the time of photoperiod decrease are the two main environmental cues controlling the induction of the reproductive cycle in Eurasian perch. GSIi was the highest (3.8%) when females were exposed to both low amplitude of temperature decrease and precocious decrease of photophase. It was the lowest (1.1%) when high amplitude of temperature decrease and late decrease of photophase were applied. Handling in association with temperature modulated the broodstock response. 100% of the unhandled fish held at 14 °C were at the exogenous vitellogenesis stage with mean E₂ and basal cortisol levels of 1.6 ng mL^− 1 and 9 ng mL^− 1 respectively. Handled fish and fish held at 6 °C exhibited lower vitellogenesis (40-73%) associated with lower E₂ (0.6-1.1 ng mL^− 1) and higher basal cortisol levels (37-89 ng mL^− 1). No other factor nor interaction displayed a cueing or non permissive effect on the induction of the reproductive cycle in female Eurasian perch. A first schematic model is proposed to explain the factorial determinism of the induction of the reproductive cycle.     

Are the long‐term fluctuations in Atlantic bluefin tuna (Thunnus thynnus) population related to environmental changes?

We tested whether synchronous, long‐term fluctuations in Atlantic bluefin tuna (Thunnus thynnus) trap catches, collected from the ancestral Mediterranean and Atlantic trap fishery, might be related to large‐scale environmental change. Nine time series of trap catches of more than 80 yr long were compared with long time series of three preselected environmental variables, i.e. the North Atlantic Oscillation (NAO), the Length of the Day Index (LOD, a proxy of the atmospheric circulation index) and the temperature. Spectral analyses of trap catches, LOD and temperature displayed similar spectra with peaks at low frequencies, whereas those of the NAO exhibited a broad band spectrum. Regression analyses and tests of correlation did not reveal any clear relationship between trap catches on the one hand and NAO and LOD on the other hand. In contrast, long‐term fluctuations in trap catches appear to be closely and negatively related to long‐term trends in temperature. Underlying processes that could explain such a relationship are discussed, with special focus on changes in migration patterns of the Atlantic bluefin tuna.     

紫苏叶多糖脱色工艺的研究(Ⅰ)——树脂

以紫苏叶多糖提取液为原料,脱色率和多糖损失率为指标,采用树脂脱色技术,通过正交试验法确定紫苏叶多糖的最佳脱色工艺条件。结果表明,紫苏叶多糖的最佳树脂脱色工艺条件为:树脂用量5.0%,pH6.0,温度70℃,时间60 min,紫苏叶多糖提取液脱色率达95.30%,多糖损失率为15.50%。脱色效果较为理想。     

中国东部平原农村居民点破碎化状况与成因分析

农村居民点破碎化导致中国农村地区公共服务设施与市政基础设施建设缺乏规模效益与服务效率,成为制约中国农村地区社会经济发展的重要因素。该研究采用空间分层取样法在中国东部平原地区选择了240个10 km×10 km的样点,以高分辨率遥感影像为数据基础,通过遥感影像目视解译、景观指数分析、热点分析等多种方法对中国东部平原农村居民点破碎化状况及其影响因素进行了研究,并分析了中国东部平原不同地区适宜的农村居民点数量与服务范围。结果表明：1）中国东部平原农村居民点破碎化程度表现为：长江中下游平原>东北平原>华北平原,破碎化程度最高的区域位于长江中下游平原,破碎化程度最低的区域位于华北平原与东北平原北部。2）气候、人口密度、耕作半径、土地开发时序、土地开发时期交通状况等自然、经济、社会因素在中国东部平原地区农村居民点空间分布格局形成过程中发挥着重要作用。3）中国东部平原地区每100 km2农村居民点数量不宜低于3～4个,每个村庄的服务范围不宜超过33.6～45.8 km2。4）华北平原为中国东部平原中开展农村居民点破碎化治理难度最大的区域,该区域尽量避免以整村迁并的形式开展农村居民点破碎化治理,而应以农户为单位,在农民自愿的基础上开展农村居民点迁并;长江中下游平原地区为中国东部平原农村居民点破碎化治理潜力最大的区域,该区域农村居民点布局优化应与农田布局调整协同推进,并根据不同地区耕作通勤状况合理确定中心村数量与位置,避免因农村居民点布局调整导致农民耕作不便。研究结果可为中国东部平原地区乡村空间重构过程中合理确定农村居民点数量与规模提供研究基础。     

环境友好型虾夷扇贝捕捞网具优化设计与试验

目前中国虾夷扇贝网具存在捕捞效果差、海底生境影响严重等问题,该研究基于水下视频监控技术,设计了水压板导流与随动式惊扰相结合的拖曳网架结构。采用FLUENT软件对改造后捕捞网具的水下拖曳水动力特性进行分析得出,在拖曳水深在30~50 m、拖曳速度为1.8 m/s、网口高度为350 mm时,采用22.5°～30°负迎角弧式水压板,可减轻顶部湍流对底栖鱼类的兼捕影响,且随动式惊扰装置满足作业要求,此时拖曳稳定绳长约为156.80～261.34 m、稳定角度为11.03°、稳定拖曳力为2275.83 N。通过海上捕捞对比试验得出,在拖曳速度为1.5、1.8和2.0 m/s时,改造后捕捞网具与生产用捕捞网具在捕捞量方面无显著差异（P>0.5）,在碎贝量和底栖鱼类兼捕量方面显著降低（P<0.5）。单网平均捕捞量的偏差率分别为6.30%、0.59%和5.55%,单网平均碎贝量的偏差率分别为90.63%、84.78%、85.29%,单网底栖鱼类平均兼捕量的偏差率分别为78.57%、81.25%、84.85%。且在拖曳速度为1.8 m/s时,与生产用网具相比,单网平均捕捞量偏差率最低,单网平均碎贝量的偏差率最低,底栖鱼类平均兼捕量显著减少,符合环境友好型捕捞网具设计要求。