美洲矾根愈伤组织诱导及其快繁技术体系研究

以矾根(Heuchera micrantha)植株不同器官为外植体材料,MS培养基为基本培养基,探索了矾根组织培养与快繁技术体系。结果表明,选取幼芽作为外植体时快繁效率最高,最适芽诱导培养基配方为MS+2.0 mg/L 6-BA+0.5 mg/L NAA,采用4/5MS+0.2 mg/LNAA的生根培养方案较为适宜。     

Single layer centrifugation of stallion spermatozoa consistently selects the most robust spermatozoa from the rest of the ejaculate in a large sample size

Reasons for performing study: An improvement in sperm quality after single layer centrifugation (SLC) has been seen in previous studies using small sample sizes (for example, n = 10 stallions). There is a need to investigate whether this improvement is repeatable over several breeding seasons with a larger number of stallions (n ≥ 30 stallions). Objective: To make a retrospective analysis of the results of SLC performed on more than 250 sperm samples (176 ejaculates) from 31 stallions in 3 consecutive breeding seasons. Methods: Sperm quality (motility, proportion of morphologically normal spermatozoa and the proportion of spermatozoa with undamaged chromatin) was assessed before and after SLC. Results: All parameters of sperm quality examined were significantly better in sperm samples after SLC than in their unselected counterparts (P<0.001 for each parameter). The yield of spermatozoa obtained after SLC was influenced by the type of extender used and also by the concentration of spermatozoa in the original ejaculate, with fewer spermatozoa being recovered when the loading dose contained a high concentration of spermatozoa. The optimal concentration was approximately 100 × 10⁶/ml. Sperm concentration in the samples loaded on to the colloid influenced the sperm yield while the type of semen extender affected sperm quality and survival. Furthermore, the scaled‐up SLC method was found to be suitable for use with a range of ejaculates, with similar sperm kinematics being observed for standard and scaled‐up preparations. Conclusions: SLC consistently improved the quality of stallion sperm samples from a large number of ejaculates. The method could be scaled‐up, allowing larger volumes of ejaculate to be processed easily from a wide range of stallions.     

论黑龙江省勃利县地下水资源管理

阐述了黑龙江省勃利县地下水取水井管理基本现状,提出了在县级水资源管理中开展对地下水取水井的管理措施。     

高校图书馆知识管理实施模式评析——以北京大学图书馆为例

简要介绍知识管理和高校图书馆知识管理的相关内容;以北京大学图书馆为例,分析国内高校图书馆知识管理实施模式,并提出不足之处和对策。     

东临复线稳态优化运行方案

基于东临复线管道概况和基础参数,回归了各泵站不同泵组合方式的特性方程,建立了运行方案优化数学模型,包括管内油流温度、总传热系数、原油密度、比热容、粘温关系的计算方法,以及原油价格和电价格的取值依据。利用热油管道稳态通用HOPOPT软件,计算了管道在大、中、小3种输量条件下,其末站在不同进站温度时的各站开泵方案、进出站压力、进出站温度及电耗、油耗情况。通过分析优化,计算得到了最佳经济运行方案,揭示了东临复线的节能潜力与进站温度的关系。     

东沙窝沙漠区不同造林技术效果分析

通过对东沙窝沙漠区采取提前整地、压沙等方式,选用良种壮苗、蘸泥浆、覆沙、平茬复壮、纯林改混交林等综合技术进行造林试验,结果表明,试验区造林成活率、保存率普遍提高,小气候环境明显改善:植被区风速比旷野区降低了25.8%～32.6%;灌木固沙林在夏季降低气温10℃左右,降低地温6～10℃,冬季地面最高温度提高2～4℃。     

我国中小银行成长性综合评价研究

通过构建商业银行成长性评价体系，利用突变级数法对14家中小银行2007~2010年的成长性进行评价，得出中小银行具有振荡向上的成长趋势，且股份制银行整体成长性优于城市商业银行，但对于影响成长性的各因素，银行间的表现不尽相同。这表明中小银行还需调整经营管理思路来保证成长的稳健和持续。     

The Alleviating Effect of Elevated CO2 on Heat Stress Susceptibility of Two Wheat (Triticum aestivum L.) Cultivars

This study analysed the alleviating effect of elevated CO₂ on stress‐induced decreases in photosynthesis and changes in carbohydrate metabolism in two wheat cultivars (Triticum aestivum L.) of different origin. The plants were grown in ambient (400 μl l^?1) and elevated (800 μl l^?1) CO₂ with a day/night temperature of 15/10 °C. At the growth stages of tillering, booting and anthesis, the plants were subjected to heat stress of 40 °C for three continuous days. Photosynthetic parameters, maximum quantum efficiency of photosystem II (PSII) photochemistry (F_v/F_m) and contents of pigments and carbohydrates in leaves were analysed before and during the stress treatments as well as after 1 day of recovery. Heat stress reduced P_N and F_v/F_m in both wheat cultivars, but plants grown in elevated CO₂ maintained higher P_N and F_v/F_m in comparison with plants grown in ambient CO₂. Heat stress reduced leaf chlorophyll contents and increased leaf sucrose contents in both cultivars grown at ambient and elevated CO₂. The content of hexoses in the leaves increased mainly in the tolerant cultivar in response to the combination of elevated CO₂ and heat stress. The results show that heat stress tolerance in wheat is related to cultivar origin, the phenological stage of the plants and can be alleviated by elevated CO₂. This confirms the complex interrelation between environmental factors and genotypic traits that influence crop performance under various climatic stresses.     

饺子皮中常用辅料的研究进展

添加辅料是解决饺子生产中常见问题的有效手段之一。这些辅料主要包括增稠剂、乳化剂、磷酸盐、酶制剂和食品组分淀粉、蛋白质等。对饺子中常用增稠剂、乳化剂、磷酸盐、淀粉和蛋白质等的研究进展进行阐述,旨在为饺子生产中辅料的选择提供参考。     

利率服从AR( m )离散 时间风险模型的破产分布

研究当保费收入在时间区间的期初和期末给付时的两种广义的离散时间的风险模型，当保险公司的利率具有 m 阶自回归结构的情况下，将其代入上述模型通过递推和数学归纳法 ，分别得到了描述破产问题的破产前最大盈余分布，破产前盈余、破产后赤字与破产前最大盈余的联合分布以及首达某一水平 x 的时间分布的满足的微分方程，最后指出可以结合具体的例子会有比较好的实际价值.