葡萄糖氧化酶基因在棉花中的高效转化——转化与抗性愈伤组织的诱导和筛选

试验探讨了利用农杆菌介导法把葡萄糖氧化酶基因（ＧＯ基因）转化到棉花中影响转化和抗性愈伤组织诱导的一些因素。结果表明,５～７ｄ 苗龄的无菌苗是做转化的最佳时期,以３Ｄ＋ ２Ｌ处理的无菌苗效果好。下胚轴的形态学部位对转化的影响差异不大。菌株的活力状态是影响转化出愈率的主要因素之一。以菌株的培养时间为依据简便有效。试验还发现,培养基的固化程度不同,出愈率有很大差异,固化程度高,异常愈伤组织增多,正常愈伤组织的出愈率降低。这可能与其活性氧平衡被打破对细胞造成伤害有关。对坑性愈伤组织的筛选次数也做了讨论。     

A review of tree fodder production and utilization within smallholder agroforestry systems in Kenya

Although the biological advantages in terms of animal production and improved soil fertility of the use of herbaceous legumes have been well demonstrated in Kenya and elsewhere, adoption by small-scale farmers has often been disappointing. This has led to increased research into the use of both indigenous and exotic fodder trees. In common with conventional pasture legumes, tree fodders contain high levels of crude protein and minerals and many show high levels of digestibility. They are readily accepted by livestock and presumably because of their deep-root systems, they continue to produce well into the dry season. Antinutritive factors can be a problem, however, and polyphenolics, toxic amino acids, cyanogenic glycosides and alkaloids are found in many tree species. There are abundant niches on small farms where fodder trees can be grown without affecting crop production. Although detailed management recommendations are lacking, guidelines exist with regard to appropriate cutting heights and harvesting frequencies. In the Embu region, it has been estimated that three kg of fresh fodder of Calliandra calothyrsus has the same effect on milk production as one kg of commercial dairy meal. Up to about 500 trees (250 m of hedgerow) will produce enough fodder to supplement one dairy cow for a complete lactation. The tree fodder can either replace the concentrate without loss of yield, or it can complement it to produce more milk. It is being enthusiastically adopted by small-scale farmers, many of whom are starting to produce their own seed. Other tree species are now being studied in order to avoid over-reliance on a single fodder species. This revised version was published online in August 2006 with corrections to the Cover Date.     

Control of retention in paper-making by colloid titration and zeta potential techniques

The concentration influence of some commercial polyethylenimines, used as retention agents, on the retention efficiency during the sheet formation is studied in this paper. The conditions of an industrial wire end have been simulated by means of a dynamic jar of exclusive design. Measurements of the zeta potential have been taken to quantify the surface charge of particles and the colloid titration ratio (quotient between the cationic demand and the anionic demand of pulp slurries) has been evaluated. Both techniques have proved convenient to monitor the retention level; therefore, they are efficient methods to control the retention level in the sheet formation. The univocal relation existing between zeta potential and the logarithm of the colloid titration ratio has been demonstrated. Finally, the variation of the level of turbulence has proved the importance of the hydrodynamics factors in the retention.     

气象生态因子对稻米品质影响的研究进展

从稻米的碾米品质、外观品质、蒸煮食味品质和营养品质４个方面,论述了气象生态因子对其影响的生态生理特征的研究进展,并对目前有关研究中存在的不足做了简要评述。     

利用投影寻踪回归技术进行草地产量预报的研究

本文利用1991～1992年在新疆阜康县不同类型草地上观测的牧草产量、环境因子和卫星遥感资料运用投影寻踪回归(PPR)技术,探讨了草地产量预报的原理与方法,建立了产量预报综合模型,其预报精度达到83.5%以上,并克服传统预报方法的一些不足,科学地提示其内在关系,进而对影响产量预报精度和产量形成的因素进行分析与实验验证。因而研究结果表明利用PPR技术基本实现了科学预报草地产量的目的。     

气候要素对松材线虫病疫情的影响研究

引入典范对应分析方法,研究了气候要素对松材线虫病疫情的影响。结果表明,不同的气象因子对松材线虫病的影响大小不同,并且在不同的松材线虫病侵染阶段也有差异。年平均风速以及与其相关的年蒸发量和相对湿度是影响定海区松材线虫病发病面积的最主要因素;年平均气温是影响定海区松材线虫病发病密度最主要的因素;冬春季降水过多会导致松材线虫病疫情严重,而6月份降水量越大,松材线虫病疫情越轻;相对湿度也是松材线虫病疫情的一个较重要影响因素,主要表现在3-5月份,与疫情轻重程度呈正相关。     

影响猪肉质因素的探讨

利用６０头杂交组合试验猪从遗传和环境两方面探讨影响肉质的因素,结果表明,７５－８５Ｖ,２４００－３０００ＨＺ的电击昏明显优于２２０Ｖ、５０ＨＺ,且对肉质无显著影响,肌肉温度若高于４０℃,则对了长肌的ＰＨ值有显著影响;遗传材料不同,肌肉品质各异,因此,规范化的宰前处理和屠宰条件是正确评判肉质的前提,遗传材料是影响肉质的主要因素。     

迎春5号杨生长评价与经营密度

迎春５号杨是牡丹江林区１９９２年从中国林科院引起的黑小杨混合系中选育出的优良无性系,该品种具有生长迅速,材质优良,抗性等优良特性,１５年生林分平均胸径达３０．１ｃｍ平均树高达２０．１ｍ,单株材积０．５１４９ｍ＾３,显著超过了小黑杨等参试品种,根据树冠面积与胸径相关关系选择数学模型进行拟合,得到ｙ＝ａ＋ｂｘ＋ｃｘ＾２＋ｄｘ＾３为最佳模型,以此编制迎春５号杨经营密度表。     

昆明地区梅花鹿养殖评价

5模拟鹿场经济效益分析5．1鹿场建设的指导思想和原则（1）肉、茸兼用是鹿场设计时的一个主导思想．在存栏梅花鹿中既要有相当数量公鹿,保持产茸量,又要有一定数量母鹿,以繁殖补充每年肉用应的消耗量．（2）提高鹿产品的综合加工能力是鹿场规划的基本原则．综合利用能提高养殖场的经济效益,鉴于昆明地区目前尚无专门的鹿产品加工厂,兴建一加工厂不仅可以加工自己的产品,而且可以面向其它养殖场．（3）鹿场规划生产年限应落在生产稳定期之后．鹿场建设大致可分为3个时期．第1期为育成期,建场的前4年基本上为幼鹿的育成阶段,该期的经…     

环境因子有效性与春小麦生育期模型的建立

研究指出：在影响春小麦生育期的众多环境因子中,温度是主导因子,其他环境因子的作用表现在对温度有效性的影响上。求出了各阶段的环境因子有效性系数,该系数能够综合定量地衡量环境因子对生育期的影响程度。提出了当量积温为环境因子有效性系数与活动积温乘积的概念。认为在环境因子不能满足的情况下,春小麦完成发育要求一定的当量积温。因春小麦不同生育阶段要求不同的环境条件,采用逐步订正法建立了生育期动态预报模型。该模