我国海钓基地建设推进路径的探讨

在当前我国海钓产业兴起之时,基地建设已被列入沿海资源型旅游城市开发利用海钓资源的实事项目之一,如何从理论与实践上解决破坏性建设与重复建设的问题成为当务之急。本文试图从基地建设的产业基础条件研究着手,通过对基地生态、环境影响要素条件的评价,结合具体实证规划研究成果,在国内业界首次提出了海钓基地建设推进路径的全新观点。认为,建立岛礁生物资源保护的长效机制是完善和保障产业基础的最主要途径;实施海洋游钓资源生态补偿制度,是实现基地建设可持续发展的基本对策。     

Development of the expressed immunoglobulin μ chain repertoire during maturation of mice B cells

In the bone marrow and spleen, the developing B cell populations undergo both negative and positive selections to shape their B cell receptor repertoire. To gain insight into the shift of the immunoglobulin heavy (IgH) chain repertoire during B cell development, we undertook large scale Ig μ chain repertoire analysis of pre-B, immature B and spleen B cell populations. We found that the majority of V_H gene segments, V_H families, J_H and D gene segments, were observed to have significantly different usage frequencies when three B cell populations were compared, but the usage profile of the V_H, D, and J_H genes between different B cell populations showed high correlations. In both productive and nonproductive rearrangements, the length of CDRH3 shortened significantly on average when B cells entered the periphery. However, the CDRH3 length distribution of nonproductive rearrangements did not follow a Gaussian distribution, but decreased successively in the order 3n-2, 3n-1 and 3n, suggesting a direct correlation between mRNA stability and CDRH3 length patterns of nonproductive rearrangements. Further analysis of the individual components comprising CDRH3 of productive rearrangements indicated that the decrease in CDRH3 length was largely due to the reduction of N addition at the 5′ and 3′ junctions. Moreover, with development, the amino acid content of CDRH3 progressed toward fewer positively charged and nonpolar residues but more polar residues. All these data indicated that the expressed Ig μ chain repertoire, especially the repertoire of CDRH3, was fine-tuned when B cells passed through several checkpoints of selection during the process of maturation.     

南朝拟古诗的新变

南朝时期,拟古诗创作非常兴盛,并且发生了一些新变。这些新变主要表现为3个方面：江淹的突破、＂永明体＂和宫体诗的倾向、古意诗的发展与军旅边塞诗的出现。这些新变促使诗歌的艺术格局日趋成熟,也扩大了拟古诗的内涵和承载,对诗歌的发展起到重要的作用。     

降雨条件下黏性土坡微结构动态环境能场分析

【目的】研究降雨条件下黏性土坡位移场、应变场、微结构动态环境能场的变化及对土坡稳定性的影响。【方法】通过室内土坡模型试验,用读数显微镜观测降雨前后土坡内45个测点的位移,特意选择并全程观测斜坡面(1个)、坡脚(2个)、坡底(1个)的4个测点的位移,研究侧向位移和竖向位移随时间的变化,利用反分析方法分析土坡的位移场与应变场的变化,从宏观、中观、微观角度上分析黏性土坡微结构动态环境能场及外部环境条件变化与其内在介质环境变化之间的关系。【结果】降雨条件下坡顶和坡脚处土体的损伤程度较大,最大竖向位移发生在坡脚处;用常规方法分析土坡变形时会低估瞬时变形而夸大固结变形;由斜坡面、坡脚和坡底的蠕变曲线可见,降雨初期的瞬时竖向位移和侧向位移增长较快,但随着降雨时间的延长,土坡微结构受到损伤,竖向位移和侧向位移的增长变慢,最后趋于稳定。【结论】降雨引发的土坡滑移大多数是瞬时的,土坡的蠕变既是土体损伤的过程,也是土坡微结构能量耗散的过程。因降雨劈裂力的作用,在坡顶及斜坡面上会出现裂缝,而斜坡面和坡脚是最容易诱发险情的部位。     

职业技能鉴定中的题库建设和命题技术研究

以化学检验工职业技能鉴定为例,对职业技能鉴定题库建设和试题编码、命题格式和命题要求等命题技术进行了系统的分析研究,提出了在合理制定鉴定要素细目表编码基础上,根据职业技能鉴定要素表命题,按照理论知识鉴定要素细目表和技能操作鉴定要素细目表中的代码进行全代码编码的编码方法,十分便于电脑随机抽取组合试卷。     

基于Shapley值的组合预测方法在福建省农业总产值预测中的应用

提出了基于Shapley值的农业总产值的组合预测方法。算例结果表明,该方法可有效提高农业总产值的预测精度。     

辽宁省果树生产发展的优势条件

辽宁省是我国水果生产大省之一,历史悠久、种类众多,虽然在多年的栽培历史过程中出现过曲折与沉浮,但总的来说还是在不断地发展和进步。现从辽宁省环境条件、区位特点、消费市场、地方经济、技术基础、特色产业等方面概括了辽宁省果树生产的优势条件,以期能够成为辽宁果业发展的原动力。     

经济、技术、生态：现代农业的三大支柱

In the beginning of the 21st century thedevelopment of the agricultural sector in most of themodem industrialized countries continues to followthe main directions that have already been laiddown, but in doing so it is influenced and challengedat the same time by a number of factors in a wideropment, besides the ongoing integration in society,are the agricultural sector's strive for an equal de-velopment in economic and social terms and the im-pact of the ongoing technological development. Itwill be affected by an accelerating globalisation andliberalisation of agricultural production and trade.This seems to give the big multinational chains afree hand for a unilateral optimization of economicprogress, facilitated by technological progress andrapidly transferable knowledge. The increasinghowever, leads to a balanced strategy, in which notonly economy (profit) but also ecology (planet) andthe norms and values of technology and societyto be a generally new three dimensional frameworkfor further development in all branches' of industry,including agriculture. It will have big consequencesfor operating and that goes for the Dutch agricultur-al sector too. This new framework which can beused as a tool for guidance in organizing and devel-oping agricultural science and technology, is elabo-rated in this contribution.     

Global distribution of rice weeds – A review

This review provides an overview on the most common rice weed species of the world. It shows that a few generalists have established in rice independent from sites, crop management systems, and local climatic conditions. Cosmopolitan weeds are even constant elements where rice cultivation started just a century ago. Local differences may be explained by cultivation methods, growing seasons, or special weed management. Some general changes in weed spectra have been observed globally in recent years. Weedy rice (Oryza sativa L.) and herbicide resistance have become general global problems within the last decades. Some global key weed genera such as Echinochloa, Cyperus, Scirpus, or Fimbristylis species are, however, still dominating rice fields despite the decade long use of well performing herbicides. On the other side, general species shifts as a result of resistance have not been observed yet. Leptochloa species started to become major problems in Asia in the end of the last century and now in Europe also. Several modern herbicides allow the control of perennial weeds, such as Cyperus rotundus L. or Eleocharis kuroguwai Ohwi which makes them no longer serious threats. Some genera in rice such as Echinochloa and Oryza (weedy rice) are characterized by an enormous germplasm variability which makes species definitions difficult. The fact that weeds in rice have to adapt to wet or aquatic conditions reduces the biodiversity range in comparison to other arable crops. Water management has a considerable impact on weed spectra. The increase of rice acreages with reduced irrigation may end up in higher weed infestations. Long term results of weed surveys in rice as they exist for other crops are, however, not available. This makes predictions on biodiversity changes in this crop quite difficult.     

西北地区“农二代”生存困境与对策

基于西北地区"农二代"在普通高等教育后存在更为严重的就业困难、职业技术教育整体来说并不完善、进城打工容易成为在城市生存却又融不进城市生活的"边缘人"、回乡务农和创业面临诸多障碍、"卖地换钱"带来巨大隐患的生存困境,建议政府从工作素质、投资帮扶、普法教育、农村政策、民生问题等方面进行改革,通过加大投入、政策支持、教育引导的举措帮助普通"农二代"摆脱生存困境。