两种一年生植物在替代试验中的相互竞争关系

（1）用替代试验研究了燕麦（Aneva sativa）和箭舌豌豆（Vicia sativa）在混播中的竞争相互作用。为了攻混播比例对两种植物在混播条件下的行为影响，田间试验设为5个混播总密度和5种混播比例，共了5次。（2）方差分析表明，相对总生物量（RYT）和竞争平衡指数（CBI）对总密度，混播比例和生长时间的反应敏感。总密度对RYT和CBI的影响高度显著，在大多数情况下，混播比例对RYT和CBI的影响不显著。（3）本文研究的结果表明，持续时间对RYT和CBI很强的影响，在第1次测定时，RYT值接近1而BI值接近0，这一事实表明，种间无竞争或互惠作用。而在生长旺盛期，种间竞争较为剧烈。（4）本研究结果表明，箭舌豌豆的生长严惩受到燕麦的抑制作用，这说明箭舌豌豆在与燕麦混播时表现为竞争上的弱者。     

桑悬浮细胞原生质体培养的研究

采用继代培养三个月后的桑子叶悬浮细胞为材料,进行了原生质体的分离和培养。桑悬浮细胞在纤维素酶、果胶酶、半纤维素酶的混合溶液中,酶解获得产量高、活力强的原生质体。原生质体在K8p(附加6—BA、NAA、2,4—D、LH)液体培养基中,再生细胞经多次分裂,得到肉眼可见的小愈伤组织。再通过增殖继代培养,获得浅黄色、具有明显颗粒结构的愈伤组织,转至各种激素含量的MSB固体培养基中,尚未获得绿苗分化。     

佐剂对鸡补体水平影响的研究

６０只未免疫的伊莎褐雄鸡雏分成４组，于２４日龄开始用试管法以５０％溶血度为标准样检测补体。３１日时Ａ，Ｂ，Ｃ三组分别皮下注射司盘－８０＋白油，氢氧化铝胶和ＢＣＧ，Ｄ组对照；４６日龄时再次注射。从３１日龄至５６日龄每隔５天检测一次。结果表明，佐剂使鸡的补体水平普遍升高。于每次注射后第５天达到高峰，第１０天左右接近正常。其中ＢＣＧ影响现大，并于５１日龄时天对照组异显著（０．０１＜Ｐ＜０．０５）．     

茶树种植密度与排列方式对个体与群体结构的通径分析

本文用通径分析方法对茶树不同种植密度与茶树骨架形成、分枝结构、蓬面结构三大要素进行对应分析,结果表明:1)随密度上升主干粗度、一、二级分枝粗度下降;2)分枝角度随密度上升而变小;3)随密度上升,小桩数随之增加,其它因子与之呈负相关。由于密度上升后,群体结构的光合面积增大,碳水化合物积累增多,而产量上升。选用合理密度与排列组合时,可用回归方程计算。     

影响奶牛初乳产量的因素探讨

奶牛初乳是指母牛分娩后7天内所分泌的乳汁。初乳中不仅含丰富的营养物质，而且含有大量的免疫因子，因此具有促进生长发育、改善胃肠道功能、增进免疫调节、延缓衰老、抵御疾病等作用，是人类功能性保健食品的重要基料。初乳及其制品被誉为天然、完美、完全、廉价的“21世纪保健食品”。我国有奶牛和改良牛426.5万头(1998)，初乳资源十分丰富，但迄今对初乳产量及其影响因素尚未见有报道，于是对此问题我们在新疆乌鲁木齐五一奶牛场进行了初步探讨。1材料收集整理原始产奶记录和产犊记录取自该场1965年至1997年资料，全都为舍饲中国荷斯坦…     

Effect of dietary vitamin C and ammonia concentration on the cellular defense response of Macrobrachium nipponense

This study examined the effects of dietary vitamin C and ammonia concentration on the cellular defense response of Macrobrachium nipponese . The response of the cellular defense was determined by monitoring changes in reactive oxygen intermediates in hemocytes, superoxide dismutase activity, catalase activity, glutathione peroxidase activity, glutathione reductase and glutathione transferase activity in muscle. The results showed that prawns fed the basal diet had a significant increase in reactive oxygen intermediates in response to exposure to ammonia-N. When dietary vitamin C was added to the feed, there was a significant decrease in reactive oxygen intermediates in response to exposure to ammonia-N. Total superoxide dismutase and glutathione peroxidase activity of prawns fed the basal diet decreased as ammonia-N increased. This decrease in activity was significantly less pronounced in prawns that were fed the dietary vitamin C supplement. In prawns that were fed the dietary vitamin C supplement there was no significant variation in catalase reductase or gluxathione reductase activity in response to variations in ammonia-N concentration. The glutathione transference activity increased at a low concentration of ammonia-N in prawns that were fed the dietary vitamin C supplement, but there was no significant variation in the prawns fed the basal diet. Overall the results indicate that dietary vitamin C supplements enhance the capacity of M. nipponese to respond to elevations in ammonia-N. This response involved several biochemical reactions known to be involved in cellular defense.     

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。     

Molecular structure of troponin C from chicken skeletal muscle at 3-angstrom resolution

The x-ray structure of chicken skeletal muscle troponin C (TnC), the Ca2+-binding subunit of the troponin complex, shows that the protein is about 70 angstroms long with an unusual dumbbell shape. The carboxyl and amino domains are separated by a single long alpha helix of about nine turns. Only the two high-affinity Ca2+-Mg2+ sites of the COOH-domain are occupied by metal ions resulting in conformational differences between the COOH- and NH2-domains. These differences are probably important in the triggering of muscle contraction by TnC. Also the structure of TnC is relevant in understanding the function of other calcium-regulated proteins, in particular that of calmodulin because of its strong similarity in amino acid sequence.     

邓恩桉组培中影响继代增殖条件的研究

探讨抗寒树种邓恩桉组培快繁中影响其继代培养的因素。实验表明,继代培养以改良MS为基本培养基,随继代次数的增加逐渐减少细胞分裂素BA和生长素NAA的浓度。最初几次继代,BA的浓度为0.5 mg/L,NAA的浓度为0.2 mg/L。然后BA的浓度逐渐降低到0.1~0.3 mg/L,NAA的浓度逐渐降至0.05~0.1 mg/L,继代5~6次后,BA的浓度保持在0.1~0.3 mg/L,NAA的浓度保持在0.05~0.1 mg/L。继代周期随季节而不同,夏季为15~25 d,春秋季为20~35 d,冬季为40~50 d,芽的月增殖系数为3~5倍,满足工厂化育苗的要求。组培苗的玻璃化和遗传变异等异常现象很少,节间长度适中,有利于生根。     

规模猪场提高初生仔猪成活率的技术措施

初生仔猪是否健康是规模养猪生产中的首要环节,如何提高初生仔猪成活率,减少初生仔猪死亡率、弱仔率是增加猪场经济效益的关键。为帮助规模猪场尽可能减少初生仔猪死亡率所造成的损失,笔者根据多年实践将初生仔猪死亡的原因和防治对策简介如下,供参考。1初生仔猪死亡原因分析1.