厦门市农村土地经营权流转及农业规模化经营探析

农村土地经营权流转及农业规模化经营是现代农业的需要。该研究基于农村土地经营权流转的历史及现状,重点分析了厦门市农地流转情况及存在的问题,并提出相应的对策建议。     

天山马鹿胚胎移植技术的研究

为培育特别优秀、经济价值高的种用公鹿,选择4头天山马鹿作供体,经过CIDR+FSH+PG诱导发情、超数排卵、人工授精,采集胚胎,获得13枚可用胚胎,将其移植给经CIDR+PMSG+PG诱导同期发情的13头天山马鹿,结果7头受体马鹿受胎。     

The quality after culture in vitro or in vivo of porcine oocytes matured and fertilized in vitro and their ability to develop to term

The quality of porcine blastocysts produced in vitro is poor in comparison with those that develop in vivo. We examined the quality of in vitro‐matured and fertilized (IVM/IVF) oocytes, their abilities to develop to blastocysts under in vivo and in vitro conditions, and the potential of the embryos to develop to term after transfer. IVM/IVF oocytes were either transferred and the embryos recovered on Days 5 and 6 (100% and 87.5%, respectively) (‘ET‐vivo’ embryos), or cultured in vitro for 5 or 6 days (‘IVC’ embryos). The proportion of blastocysts differed significantly between the two groups on Day 5 (20.6% and 8.0%, respectively), but not on Day 6 (23.8% and 21.2%, respectively). The mean number of cells in ET‐vivo blastocysts on Days 5 or 6 was significantly higher (72.8 and 78.7, respectively) than that in IVC blastocysts (22.1 and 39.7, respectively). When IVM/IVF oocytes and IVC blastocysts on Day 6 were transferred, all (three and three, respectively) developed to piglets (16 and 16, respectively), without any difference in the rates of development to term (2.1% and 2.6%, respectively). These data suggest that, although blastocyst production differs between the two culture conditions, IVM/IVF oocytes possess the same ability to develop to term.     

北京市郊区农地流转对农户收入的影响

基于北京市郊区345户农户调研数据,实证分析农地流转对农户家庭收入的影响。首先,农地流入显著提高了农户家庭人均收入水平,农地流出则对农户收入水平影响不显著。农地流入概率每增加1%,家庭人均收入提高67.55元。其次,农地流入对0.6和0.8分位数家庭人均农业收入显著为正,对其他家庭收入作用不显著。农地流出对0.6和0.8分位数家庭人均农业收入和人均非农收入作用分别为显著为负和显著为正,对其他家庭人均农业收入作用不显著。因此,农村家庭存在农业剩余劳动力,且存在一定的资源错配。政府应继续鼓励北京市郊区农村农地流转,持续提高农村地区非农就业力度,提升农村农地和劳动力资源配置效率。     

涉农高校技术转移中心管理模式研究

针对农业技术的特点,农业科技成果转化有其自身的规律和特征,涉农高校技术转移管 理部门要建立推转一体化的管理模式。以安徽农业大学和江南大学的模式,有效的将横向合同 管理,公益推广体系、知识产权建设及平台搭建有机结合起来。     

Performance evaluation of venturi aeration system

The venturi aeration is an effective practice to increase the dissolved oxygen accessibility in the water bodies. This study aims to optimize the various geometrical parameters of the venturi aeration system. A non-dimensional technique was applied to find the optimum performance of various geometric parameters i.e. throat lengths (t_l), number of air holes (N), and converging and diverging angles (α and β). These experiments have been carried out using 1124 L capacity of tank having dimensions of 105 cm long, 105 cm wide and 102 cm deep. The experiments were conducted at a constant flow velocity of water (1.096 m/s) with varying throat length (t_l = 20–100 mm keeping 20 mm as interval between two consecutive length), number of air holes (N = 1–17 at an equal hole to hole distance of 5 mm between them), and converging and diverging angles (α and β = 10°, 15°, 20° and 25°). Multiple non-linear regression equations were also developed from the linear relation with the dependent variable (Non-dimensional form of standard aeration efficiency, NDSAE) and independent variables (t_l and N). With the geometrically optimized venturi aerator the optimum performance was found for t_l =100 mm, N = 17, and α and β = 15°. The maximum value of standard oxygen transfer rate (SOTR) and standard aeration efficiency (SAE) obtained was 0.0216 kgO₂/h and 0.611 kgO₂/kWh respectively. From the non-dimensional study, it was found that the NDSAE is the function Reynolds number (Re) and Froude number (Fr). The simulation equations were developed on the basis of Re and Fr for NDSAE, and subjected to 7.378 × 10⁻⁶ < Re < 3.689 × 10^-5 and 0.163 < Fr < 0.817, respectively.     

直接利用传递函数对分叉结构进行模态综合

建立了一种直接利用传递函数对分叉结构进行模态综合的方法。传统的方法一般都需要对大矩阵进行求逆运算,而此方法只涉及分叉结构结合部的传递函数矩阵的求逆,因此求逆计算量很小,特别是当直接采用传递函数的测量值进行模态综合时,就更体现出它的优越性。     

通过多基因组比较的方法在5种绿球蓝细菌中识别基因组岛(英文)

为探索水平基因转移在绿球蓝细菌基因组多样性中的作用,5个高光适应性绿球蓝细菌基因组被比较.先用BLASTP两两最佳匹配搜索和基因位置保守性的方法预测直系同源基因,并进一步计算每个基因组中所有基因在其他4种绿球蓝细菌基因组中直系同源基因的数量,从而达到识别外源基因的目的;而基因组岛是指由1个或几个连续外源基因组成的区域.结果表明:在5个绿球蓝细菌基因组中共识别出了16至52个不等的基因组岛,它们中的许多基因在病毒基因组或富含病毒的环境样本中都有同源基因.以上这些结果显示,在绿球蓝细菌中,病毒可能介导了基因的水平转移,从而导致了基因组的多样性.     

兽药磺胺二甲嘧啶在土壤中的生态行为

通过室内培养和土壤薄层层析等实验方法，研究了磺胺二甲嘧啶对土壤微生物的毒性及其在土壤中的降解、迁移特性。结果显示：在土壤磺胺二甲嘧啶浓度为1mg kg^-1时，土壤中细菌和真菌数量明显减少（p〈0．05），但随时间延长，该抑制作用变缓；磺胺二甲嘧啶在土壤中降解缓慢，持留时间久，在灭菌土和未灭菌土中的半衰期分别为223．9d和102．4d，并容易在土壤中迁移和渗漏，迁移系数R大于0．7，迁移和渗漏速度受介质pH的影响，在非中性环境下，移动和渗漏能力增强。表明磺胺二甲嘧啶是一种在土壤中不易被降解、容易迁移和渗漏到水体、对土壤微生物和水体产生危害的新型污染源。     

黄河小浪底水库蓄水前后库周土地覆被变化研究

选取黄河小浪底水库库周1993年和2000年TM遥感影像进行土地覆被变化分析,绘制出蓄水前后的土地利用现状图,计算出土地覆被变化的转移矩阵和景观结构的控制指标,分别从土地利用类型、空间景观结构特征及土地变化过程等方面进行了研究.研究结果表明:小浪底水库的施工和蓄水对库周的土地利用变化和空间景观结构的改变没有太大影响;由于林地向耕地和其它土地覆被类型转变,使得1993～2000年的模地类型由有林地向耕地转化