早稻-再生稻不同育秧方式对产量的影响

为探讨软盘抛秧和旱育秧在早稻—再生稻上的增产效果,通过田间简比试验,结果表明:早稻—再生稻应用软盘抛栽和旱育秧技术,能提高秧苗素质,插后大田分蘖力强,增加有效穗和千粒重,每667 m2全年产量分别为842.2 kg和815.2 kg,分别比水秧(旱稻—再生稻全年产量652.1 kg)增产190.1 kg和163.1 kg,纯收入增加264.1元和234.9元,值得推广。     

稻瘟病的防治技术

稻瘟病又称稻热病 ,属真菌病害 ,是水稻主要病害之一。水稻整个生育期都会发病 ,因危害稻苗、稻叶、穗颈、稻节、稻粒等 ,故称为苗瘟、叶瘟、穗颈瘟、节病、谷粒病。特别是苗瘟、叶瘟和穗颈瘟常会危害成灾 ,是水稻优质、高产的大敌。正阳县 2万ｈｍ2 水稻发病 1.12万ｈｍ2 ,一般减产 15 %～ 2 0 % ,严重的高达 40 %以上。1　症状1.1　苗瘟多由种子带菌引起 ,早稻、麦茬稻秧田发病严重。三叶期前一般形不成明显病斑 ,幼苗多变黄褐色 ,而后枯死 ;三叶期后发生在叶片上 (即苗叶瘟 ) ,病斑短纺锤形至棱形 ,或密布不规则的小斑 ,灰绿色或褐色 ,天…     

Phase Transitions and Nonplanar Conformers in Crystalline n-Alkanes

Crystals of n-alkanes show a remarkable series of solid-solid phase transitions. In the odd n-alkanes C(25), C(27), and C(29) a previously unknown transition is found by both calorimetry and infrared spectroscopy. The ubiquitous presence of nonplanar conformations of the chains is shown by infrared spectroscopy. The nonplanar conformers constitute approximately half the molecules in the highest temperature solid phase of C(29).     

番茄灰霉病菌生物防治菌的筛选试验

采用多种筛选方法，从保护地土壤和番茄病果上，分离筛选对灰霉病菌有营养竞争和抑制作用的菌株。结果表明，在分离获得的细菌165株、真菌93株、放线菌210株中，细菌、真菌以营养和空间竞争作用为主，而放线菌生长缓慢，以产生抑菌物质为主，约有20％的放线菌表现出有抑菌作用；离体叶筛选灰霉病生防菌结果表明，细菌x24、x28，真菌z45、z120与放线菌f15、f111、f163均具有较好防治效果。     

A common fold mediates vertebrate defense and bacterial attack

Proteins containing membrane attack complex/perforin (MACPF) domains play important roles in vertebrate immunity, embryonic development, and neural-cell migration. In vertebrates, the ninth component of complement and perforin form oligomeric pores that lyse bacteria and kill virus-infected cells, respectively. However, the mechanism of MACPF function is unknown. We determined the crystal structure of a bacterial MACPF protein, Plu-MACPF from Photorhabdus luminescens, to 2.0 angstrom resolution. The MACPF domain reveals structural similarity with poreforming cholesterol-dependent cytolysins (CDCs) from Gram-positive bacteria. This suggests that lytic MACPF proteins may use a CDC-like mechanism to form pores and disrupt cell membranes. Sequence similarity between bacterial and vertebrate MACPF domains suggests that the fold of the CDCs, a family of proteins important for bacterial pathogenesis, is probably used by vertebrates for defense against infection.     

1979J3: Discovery of a Previously Unknown Satellite of Jupiter

During a detailed search of Voyager 1 frames for additional observations of the satellite 1979J1, two small dark spots were observed in transit in several consecutive wide-angle frames of the Jovian atmosphere. The size, spacing, and motion of these pairs of dark spots indicated that they were the images of 1979J1 and its shadow. Subsequent analysis of images spanning 6 days, however, proved that the satellite observed in these Voyager 1 frames would have been occulted by Jupiter at the times of the Voyager 2 images of 1979J1 and was, therefore, a new satellite. It was subsequently found in transit on Voyager 2 images within 13 degrees of the Voyager 1 prediction. Its period is 7 hours 4 minutes 30 seconds +/- 3 seconds, and its mean distance is 1.793 Jupiter radii (Jupiter radius = 71,400 kilometers). The observable profile appears to be roughly circular with a diameter of 40 kilometers, and the albedo is approximately 0.05, similar to Amalthea's.     

不同NAD含量条件下培养的猪胸膜肺炎放线杆菌对小白鼠致病性和免疫保护性的影响

将在含体积分数为0.050%、0.001%的尼克酰胺腺嘌呤二核苷酸(NAD)的LB培养基中培养的血清5型猪胸膜肺炎放线杆菌(APP),分别以3×109CFU.只-1的菌量对30日龄小白鼠进行接种,观察不同NAD含量条件下培养的APP对小白鼠致病性的影响.结果表明:用0.001%NAD培养的血清5型APP对小白鼠的致病性较强,小白鼠接种APP后,多数表现肺脏严重出血;而用0.050%NAD培养的血清5型APP接种小白鼠后,只有少数小白鼠肺脏出血严重,多数表现为轻度出血.将上述条件培养的APP按常规方法制备油乳剂灭活疫苗,分别在第3周龄和第6周龄对小白鼠进行免疫接种,在2免后3周对免疫的小白鼠进行同源攻击,并对免疫前后小白鼠的抗体效价进行检测.结果表明:分别用0.050%、0.001%NAD培养的血清5型APP制备的灭活疫苗,对小白鼠的保护率差异不显著;用0.001%NAD培养的血清5型APP制备的灭活疫苗免疫小白鼠,用血清5型APP同源攻击后,发病的小白鼠肺脏出血较轻,而用0.050%NAD培养的疫苗免疫小白鼠攻毒后,发病的小白鼠肺脏出血严重.可见在不同NAD含量条件下培养的APP对小白鼠的致病性和免疫保护力不同.     

景电灌区脆弱生态环境对农业生产的影响

景电灌区生态系统脆弱，土地荒漠化严重，灾害性天气频繁发生，给农业生产带来严重危害。针对区域内的生态环境特点和自然状况，建立农林复合经营系统、调整产业结构、防止土壤次生盐渍化是改善灌区脆弱生态环境，减轻自然灾害，提高农业生产的有效措施。     

栽培稻抗旱种质资源利用浅析

我国淡水资源匮乏 ,北方稻区春旱发生的机率为60 %～ 80 % ,限制了农业生产的可持续发展 ,在水浸地和低洼地实行水稻旱作 ,是 2 1世纪农业可持续发展的重要措施之一。而发展旱稻其首要条件是拥有耐旱性较强的旱稻品种。从栽培稻的起源与演变过程以及对其遗传和生理的研究结果看 ,通过对现有水稻遗传资源的改良利用 ,可以满足这一条件[9] 。1　从进化的角度分析栽培稻抗旱种质资源栽培稻 (ＯｒｙｚａｓａｔｉｖａＬ .)已具备在水旱条件下生长的潜能。栽培稻起源于沼泽地区 ,水稻是基本型 ,在漫长的演变过程中 ,引向山地成为陆稻和旱稻。因此 …     

西农1376小麦性状表现及高产栽培技术研究

本文分析了西农１３７６品种的主要特征特性及对陕西关中灌区自然、生产条件的适应性，并依据产量试验和大田生产资料分析探讨了该品种的生产潜力及公倾产量超７．５ｔ的群体动态与产量结构以及主要高产栽培技术措施。