浅谈发展“两型农业”的途径和配套措施

发展资源节约型、环境友好型农业,既是加快经济发展方式转变,建设"两型社会"的重要基础,又是实现农业可持续发展,建设具有中国特色现代农业的必由之路。     

企业品牌羊肉消费者购买行为及影响因素分析——基于呼和浩特市城市居民的调研

基于内蒙古呼和浩特市城市居民的调研,运用Logistic模型对消费者企业品牌羊肉的购买行为进行实证分析,探讨消费者购买企业品牌羊肉的主要动因、特征及影响因素。结果表明,质量安全有保证是消费者选择购买企业品牌羊肉的主要动因,消费者对企业品牌羊肉的信任度较高,但对企业品牌的识别能力、忠诚度和溢价支付能力等偏低。消费者对羊肉质量安全隐患存在的感知、是否经常搜寻企业品牌羊肉的相关信息、对企业品牌羊肉的信任程度、企业品牌宣传的影响程度和主要购买场所5个变量正向影响消费者对企业品牌羊肉的购买行为,而年龄则对消费者企业品牌羊肉购买行为有显著的负向影响。提出企业要加强品牌羊肉产品的质量安全,强化品牌宣传,合理选择和拓展销售渠道,重视市场细分和品类创新,政府要加强对企业品牌羊肉产品的质量安全控制与监管。     

植物人工染色体：下一代基因工程的载体

 植物基因工程技术中的多基因转化及转基因安全已经成为其研究的2个重要方面。植物人工染色体可以在一条不含标记基因的附加染色体上提供稳定的多基因表达,是新一代的转基因载体。由于植物人工染色体独立于宿主染色体,为植物育种提供了便利,同时,也为研究染色质特殊区域的结构与功能提供了平台。本文就植物人工染色体的产生、研究现状及其应用前景等进行了综述和讨论。     

Great lakes eutrophication: the effect of point source control of total phosphorus

A mathematical model of the Great Lakes total phosphorus budgets indicates that a 1 milligram per liter effluent restriction for point sources would result in significant improvement in the trophic status of most of the system. However, because large areas of their drainage basins are devoted to agriculture or are urbanized, western Lake Erie, lower Green Bay, and Saginaw Bay may require non-point source controls to effect significant improvements in their trophic status.     

Spontaneous kidney tumors in the frog: rate of occurrence in isolated adults

Kidney tumors in the frog are thought to be virus-caused and naturally transmitted. The present report indicates that natural transmission between mature adults is not a factor in spontaneous tumor development and implies primary infection at earlier stages if a virus is indeed involved. Parasitism and nutritional state appear to be of little significance.     

宫腔填塞联合水囊压迫止血治疗凶险性前置胎盘30例临床观察

目的 观察宫腔填塞联合水囊压迫在凶险性前置胎盘救治中的止血效果.方法 采用宫腔填塞联合水囊压迫止血的30例凶险性前置胎盘为观察组,采取8字缝合加B-Lynch缝合术止血的26例凶险性前置胎盘作为对照组,比较两组的手术时间、产后出血量、DIC发生率和子宫切除率.结果 观察组手术时间为(60.2±15.3)min,产后出血量为(1050±358) mL;对照组的手术时间为(83.5±23.6)min,产后出血量为(2023±527) mL,两组比较差异均有统计学意义(均P＜0.01).两组的DIC发生率及子宫切除率差异无统计学意义(P＞0.05).结论 宫腔填塞联合水囊压迫止血可明显减少凶险性前置胎盘产后出血量,是一种较安全有效的止血方法.     

Dominoes and clocks: the union of two views of the cell cycle

We review the recent advances in understanding transitions within the cell cycle. These have come from both genetic and biochemical approaches. We discuss the phylogenetic conservation of the mechanisms that induce mitosis and their implications for other transitions in the cell cycle.     

财政支农与粮食增产:总量与结构分析

随着财政支农占总投入比例不断上升,相对份额波动下滑,厘清财政支农与农业发展的关系便显得尤为重要。本文基于舒尔茨农业理论和粮食产量视角,利用时间序列和面板数据,采用VAR、固定效应和SUR模型,分析了财政支农对粮食增产的影响以及增产效应。结果表明,财政支农与粮食产量在长期存在一定相关性,若农户私人资本投入和财政支农每增加1%,则中国粮食产量将分别增加0.315%和0.094%,相对农户私人资本投入,财政支农效应稍弱。在财政支农各细项费用中,农村综合改革有利于粮食保产增产,但其占财政支农比例较低;补贴补助、行政管理费用和科技投入对粮食增产都有显著的促进作用,而对于行政管理费用来说,相比扩大其规模,提高行政运行效率更加重要。因此,从粮食保产增产的角度,提出持续扩大财政支农规模、重视行政管理费用与农业补贴的投入、适当控制基础设施建设费用等政策建议。     

Self-renewal and cancer of the gut: two sides of a coin

The intestinal epithelium follows the paradigms of stem cell biology established for other self-renewing tissues. With a unique topology, it constitutes a two-dimensional structure folded into valleys and hills: the proliferative crypts and the differentiated villi. Its unprecedented self-renewal rate appears reflected in a high susceptibility to malignant transformation. The molecular mechanisms that control homeostatic self-renewal and those that underlie colorectal cancer are remarkably symmetrical. Here, we discuss the biology of the intestinal epithelium, emphasizing the roles played by Wnt, bone morphogenic protein, and Notch signaling cascades in epithelial self-renewal and cancer.     

Compound eyes: localization of two color receptors in the same ommatidium

The compound eye of the cockroach Periplaneta has receptors for ultraviolet light (maximum sensitivity at 365 nanometers) and green light (maximum sensitivity at 510 nanometers). Single photoreceptor cells in the compound eye were impaled, identified by spectral response, and marked with dye-filled microelectrodes. Using two diferent dyes, we showed that both types of receptors can be found in the same ommatidium.     

金融支持农业现代化发展实证研究?——基于湖南省宏观数据分析

提高金融支持农业现代化效率,有助于提升农业现代化发展水平,加快全面建成小康社会的步伐。基于湖南2005-2014年的相关数据,采用因子分析法和多元线性回归法,分析湖南金融支持农业现代化的促进作用,探讨湖南金融支持农业现代化的影响因素。结果表明,人均农业存款越多,越能为农业现代化的发展提供资金,金融支农效率就越高;金融从业人员数量越多,说明金融服务的覆盖面越广,有利于提高金融服务水平;而二元经济结构制约城乡协调发展,严重阻碍了农业现代化进程;农村金融机构覆盖率与金融支农呈负向显著关系,这表明仅仅依靠增加金融机构数量不能有效提高金融支农效率。因此,为提高金融支农效率和加快金融支持农业现代化发展,提出扩大金融机构和金融从业人员的覆盖面,提高农村金融服务水平;鼓励吸收农业存款,加大对农业现代化的资金供给;破除城乡二元结构的障碍,推动农业现代化发展等措施。     

Precession of the Earth as the Cause of Geomagnetism: Experiments lend support to the proposal that precessional torques drive the earth's dynamo

I have proposed that the precessional torques acting on the earth can sustain a turbulent hydromagnetic flow in the molten core. A gross balance of the Coriolis force, the Lorentz force, and the precessional force in the core fluid provided estimates of the fluid velocity and the interior magnetic field characteristic of such flow. Then these numbers and a balance of the processes responsible for the decay and regeneration of the magnetic field provided an estimate of the magnetic field external to the core. This external field is in keeping with the observations, but its value is dependent upon the speculative value for the electrical conductivity of core material. The proposal that turbulent flow due to precession can occur in the core was tested in a study of nonmagnetic laboratory flows induced by the steady precession of fluid-filled rotating spheroids. It was found that these flows exhibit both small wavelike instabilities and violent finite-amplitude instability to turbulent motion above critical values of the precession rate. The observed critical parameters indicate that a laminar flow in the core, due to the earth's precession, would have weak hydrodynamic instabilities at most, but that finite-amplitude hydromagnetic instability could lead to fully turbulent flow.