山东省乡村聚落景观空间布局模式分析

结合山东省乡村聚落的实际情况,依据人工干扰程度的不同,将乡村聚落分为城市边缘区乡村聚落、平原型乡村聚落及山地型乡村聚落。将聚落景观空间概括为点、线、面3个要素。依据不同类型的乡村聚落,将聚落景观空间三要素进行布局,以找到适合的模式。     

中国乡村的“空心村”现象原因分析

改革开放促进了中国农村社会经济的发展,同时出现了“空心村”问题。“空心村”现象出现有其深刻的原因,学术界主要归纳为国家政策城乡差异化、经济转型与民工潮涌动,本文则认为,其深层次则是应该是住宅商品化进程、明代以来民宅选址所考虑的因素发生重大变化等的结果,这其实这是一种正常的社会现象,是1840年以来传统社会向现代社会转型的继续,即人们先是摆脱宗族和地缘聚居模式,向现代个性特征模式转变;是传统的着眼于安全考虑的聚居型向现代方便、舒适型,便于商品化发展的转变,是对中国乡村社会的传统村落格局进行重新构建。通过分析“空心村”问题产生的原因,指出政府要通过系列改革行动有机地改变空心村所带来的负面效应,有针对性地拿出解决问题的对策。     

Assessment of spat collector ropes in Galician mussel farming

The large amount of mussel seed required to support the present mussel farming production levels in Galicia (NW Spain) forces the development of new designs in artificial spat collectors for continual improvement of mussel seed gathering. In the present study, we have assessed both settlement and recruitment of Mytilus galloprovincialis on four different collector ropes in the Ría de Ares-Betanzos (Galicia). Besides the traditional collector ropes (lacing without loops and non-filamentous structure; NF-NL), three new rope designs with different lacing and structures were evaluated; ropes with a filamentous loop complement (F-L), ropes with a non-filamentous loop complement (NF-L) and filamentous ropes without loops (F-NL). Ropes with loops showed higher settlement densities (53,925 ± 4625 and 42,433 ± 5525 indiv./m for F-L and NF-L, respectively) than ropes without loops (26,475 ± 3875 and 13,033 ± 1136 indiv./m for F-NL and NF-NL, respectively). This may be explained by the increase in available surface area provided by the loops. Several studies recognized the importance of filamentous substrata for mussel spat settlement, which may help to explain greater settlement densities on filamentous structures between ropes with the same lacing. In recruitment evaluation, ropes with filamentous loops showed the highest densities expressed in indiv./m (5493 ± 587) as was the case of settlement. However, when density was expressed in kg/m, the ropes with non-filamentous loops had a higher yield (8.48 ± 0.22 kg/m), that could be a result of differences in adjusted shell length between ropes. Intra-specific competition and predation were identified as important factors affecting post-settlement mortality. The latter factors could also influence population length distribution. Ropes with rigid loops (NF-L) may supply refuges for spat from predators and therefore, enhance the recruitment of larger individuals, although other factors like size selective settlement could play a significant role in this result.     

后浇带施工技术在水电站底板中的应用

根据后浇带在内蒙古河套灌区总干渠第2分水枢纽水电站底板中的应用情况,对后浇带的设计及施工工艺作了论述与分析.采用后浇带处理电站底板大体积混凝土,增强厂房整体性,减小施工期间混凝土水化热产生的约束应力,解决了运行期间稳定问题,达到了预期目的,取得了良好效果,进而提高了建筑物的施工质量.     

工艺条件设置与随堂考核在药物化学实验教学中的应用

为改进目前药物化学实验内容工艺单一,枯燥及成绩考核不便量化等困境,在以往教学实践的基础上,把工艺条件设置及随堂考核制度应用于课堂教学中,以在有限的时间及空间内拓宽实验内容,加深学生对合成工艺重要性的认识,并调动学生学习的主动性和积极性。     

农民工定居转移的影响因素

在对农民工迁居城市的影响因素和农民工放弃永久性迁居城市的解释进行综述,把定居方式选择（migration）作为因变量,把性别（sex）、年龄（age）、相对月总收入（income）、教育程度（edu）、工作经验（exp）、社会关系（relation）、社会保险（security）设定为自变量,采用2009中国农业大学国家大学生创新性实验计划调查所得的数据,利用Logistic二元选择模型构建相关的计量经济模型测算各影响因素对定居方式选择的影响程度。结果表明,教育水平、个人能力、社会关系与社会保障是决定农民工举家永久迁居城市的主要影响因素,人力资本与社会保障对于提高农民工收入、改善其生活质量具有重要意义。     

Chemical cues promote settlement in larvae of the green-lipped mussel, Perna canaliculus

The large (70,000 tonnes) mussel aquaculture industry for the endemic New Zealand green-lipped mussel, Perna canaliculus Gmelin, currently relies almost entirely (80%) on wild caught seed that is often harvested attached to great quantities of floating algae. Natural vagaries in catches of wild mussel seed frequently result in shortages of mussel seed that, at times, have severely affected commercial aquaculture production. Both field and laboratory experiments were used to establish that chemical cues derived from algae significantly increase settlement of mussel larvae on artificial substrates. This is the first time an algal chemical cue has been implicated in the settlement behavior of P. canaliculus larvae. These results have potential commercial implications for improving mussel seed supply through inducing higher or more reliable levels of mussel settlement for aquaculture seed collection.     

Larval rearing of calico scallops, Argopecten gibbus, in a flow-through system

A flow-through (FT) culture system is described for calico scallop, Argopecten gibbus, larvae. Its performance was assessed by larval survival rate, shell growth, settlement rate and post-larval shell growth for the duration of larval life (13 days). Comparisons were made with larvae reared in standard static system (S). Effect of increased larval density on FT performance was also investigated. With comparable larval densities, survival rate of Day 2 larvae to pediveliger stage was similar in both larval rearing systems. Shell growth for FT-reared larvae was comparable or significantly higher than in the static system (P < 0.01). Settlement rate of pediveligers was comparable for both systems, averaging 30.7%, and no significant difference was seen in shell growth of FT- and static-reared pediveligers. Increased initial larval density did not affect survival rate in FT, but did negatively affect larval shell growth, settlement rate and post-larval shell growth yielding lower growth and minimal settlement rate (10.9 ± 2.8%) compared to the static system. This FT system was successful as larval rearing system, optimising space allocation in the hatchery, reducing labour, and eliminating the use of antibiotics. Optimising initial larval density within the system needs to be investigated in association with food ration.     

“客居姑爷”：一种婚姻居住模式现象初探——基于对辽东双村的考察

“客居姑爷”一种有别于从夫居、从妻居和“两头走”的流动婚姻居住模式,在一些地方流行开来.“客居姑爷”以其客居的身份而不同于“上门女婿”,在家庭财产分配、赡养义务和村庄资源的分配上也其独特的内涵.在理解“客居姑爷”婚居现象产生的社会机制基础上,本文也关注了其现象所带来的社会意义.