绵羊妊娠识别、建立和维持的信号系统     

巨向红  雍艳红  余四九 《家畜生态》2009,(3)

妊娠的建立和维持归因于胚体的信号和黄体对孕酮的产生,在反刍动物,胚体滋养层分泌的激素抑制子宫内膜产生前列腺素PGF2α。在发情周期的绵羊,孕酮下调子宫内膜腔上皮和子宫腺上皮孕酮受体基因的表达,并伴随着上皮雌激素受体和催产素受体的增加。在催产素的作用下,子宫开始分泌溶黄体作用的前列腺素F2α。在妊娠绵羊,孕体滋养层产生的干扰素可作用于子宫内膜而直接抑制雌激素受体基因和催产素受体基因的转录。孕酮、干扰素、胎盘催乳素和生殖激素共同组成了一个"作用网络"来调节子宫的功能分化和子宫腺的形态发生,从而维持绵羊妊娠。本文综述了绵羊妊娠识别、建立和维持的信号系统。  相似文献   

现代物业小区车辆智能化综合管理系统     

彭晓燕  谭鹤良  陈源 《湖南农业大学学报(自然科学版)》2000,27(2)

给出了一种现代物业小区车辆智能化综合管理系统，由物业管理中心的中央计算机和下层的各个小区服务器构成多级控制的网络化管理系统，怪实现进出车辆的登记识别、计时计费、等多种功能，并提出了一种能有效识别车辆特征的方法。  相似文献   

桃树废弃幼果的利用     

黄漫青  周湘元 《北京农学院学报》1999,14(3):39-42

利用春天桃树疏果时疏下来的小桃为原料，借鉴了南方蜜饯的制作特点，研制开发出３种风味独特的低糖桃脯，并介绍了它们的工艺流程和操作要点，具有良好的开发前景．  相似文献   

如何减轻果蔬储藏中侵染性病害     

李秋玉  王维坚等 《吉林粮食高等专科学校学报》1999,14(4):22-23,41

采用了辐射与低温臭氧相结合的方法，可以减轻果蔬储藏中的侵染性病害，同时，还可以延长果蔬的保鲜期。  相似文献   

老岭自然保护区的野生果树种质资源   总被引：4，自引：1，他引：3  

徐兴友 《河北林果研究》1998,13(1):79-82

青龙县老岭的野生果树种质资源比较丰富，初步查明有１２种，５０种。简要叙述了主要种的生物学特点及用途，进行了必要的讨论。  相似文献   

含N三臂类肽的合成     

马兰  赖琼钰  杨绍利 《西南林学院学报》2008,28(3):48-50

利用胺分子中氮原子成键的空间特征，接上3个含有S，N杂原子的氨基酸侧链从而合成了穴醚状含N三臂类肽，其独特的分子结构对客体识别具有重要的实践价值．  相似文献   

Changes on carbohydrates and nitrogen content in the bark tissues induced by artificial chilling and its relationship with dormancy bud break in Prunus sp.     

D. González-Rossia  C. Reig  V. Dovis  N. Gariglio  M. Agustí 《Scientia Horticulturae》2008

Stem cuttings of peach, nectarine, plum and apricot, obtained from 1-year-old shoots at leaf drop in autumn, were exposed at a constant 3.0 ± 0.1 °C to simulate different chilling accumulation treatments (0, 500, and 1000 chilling hours). A set of 10 excised shoots was forced to budbreak after chilling accumulation; a second set of 10 excised shoots was used to analyse sugars, starch, and ammonium-, nitric- and proteinaceous-nitrogen content in the bark tissues. Sorbitol, fructose and glucose were the main sugars in the bark tissues, whereas sucrose and rafinose showed the lowest quantities in all Prunus sp. studied. Sorbitol and starch concentration decreased whereas glucose and fructose concentration increased with chilling. Ammonium-nitrogen showed the more dramatic increase with medium chilling treatment, decreasing again at high chilling exposure. No modifications in proteinaceous- and nitric-nitrogen levels were observed due to chilling. Chilling treatments increasing flowering intensity showed high ammonium- and proteinaceous-nitrogen content in the bark tissues of the stem cuttings, whereas those reducing flowering intensity showed high starch and nitric-nitrogen content, in three of the four Prunus sp. studied. Ammonium-nitrogen content gives the highest correlation with flowering intensity.  相似文献   

膨大素处理对葡萄果实性状的影响   总被引：3，自引：0，他引：3  

于万春  高庆玉  戴正 《黑龙江农业科学》2008,(6)

以京亚和京秀两个葡萄品种为试材,以膨大素处理葡萄果实,结果表明:以花后15 d、浓度10 mg·kg-1的效果为最好.京亚和京秀两个品种座果率增加16.8%和10.3%;单果质量增加36.7%和28.7%;穗重增加47.9%和25.7%;果形指数减少0.036和0.048.果实中可溶性糖、有机酸和维生素C含量略有下降,增加果实的糖酸比.果实前期赤霉素含量增加,增加了果实的座果率;脱落酸含量的提高促进了代谢库细胞对同化物的吸收.  相似文献   

A new descriptive method for fruit firmness changes with various softening patterns of kiwifruit     

《Postharvest Biology and Technology》2013

We have proposed a new interpretation of fruit softening. This was accomplished by generating a hypothesis that probabilities of decay of fruit structure obey the Weibull probabilistic model that has been used in the field of reliability engineering. The elasticity of individual kiwifruit after harvest was continually and nondestructively measured until decomposition by using a laser Doppler vibrometer. The obtained decreasing pattern of elasticity of individual fruit was complex, diverse, and inhomogeneous. Nonetheless, it was satisfactorily explained by a tandem combination of 2 Weibull models involving 4 types of parameters: “shape” related to probability; “scale,” to velocity of decay; “location,” to time lag; and “mixing ratio,” to contribution of the 2 models. Averages of location, shape, and mixing ratio parameters obtained by the measurement of 33 fruit were significantly different between the 2 models, but the scale parameter was not. The results suggested that the complex softening patterns of individual kiwifruit could be described using the tandem model of Weibull distribution, and that the softening process of kiwifruit consisted of at least 2 independent decay phases that are characterized by 2 of 5 parameters: location and mixing ratio. Commencement of the first decay phase could be caused by ethylene treatment after harvest, and the second one spontaneously triggered after a certain time lag.  相似文献   

“听音辨形”——英语现场新闻听力理解的先决条件     

黄荣平 《四川畜牧兽医学院学报》2009,(3):146-151

从英语现场新闻的语音规律和语境功能的角度认识“听音辨形”的实现途径，从语音认知本质的角度尝试提高“听音辨形”的教学方法，认为英语现场新闻语音在语流中的音变规律是“听音辨形”的关键凭借，其背景声音有时候是“听音辨形”的有效辅助；由于“感知磁效”现象表明听者通过“原型音”来识别语音变体，这就意味着要从本质上提高“听音辨形”，就应拓展听者识别语音变体的能力，因而听写是从根本上提高“听音辨形”的有效方法。  相似文献