辽宁沿海养殖对虾爆发性病害的病因分析

辽宁沿海养殖对虾爆发性病害的病因分析国际翔，王丽霞，李文清，刘丹孙伯伦（中国科学院沈阳应用生态研究所，沈阳１１００１５）（阳锦州水产所）９３年辽宁沿海养殖对虾发生了爆发性流行性病害，受害面积之大，损失之严重，是养虾史上前所未有的。作者对辽宁沿海６市、...

黄土丘陵区流域生物量和气体调节服务功能价值动态变化及评价

文章研究纸坊沟流域内草地、农地、林地、灌丛四种不同生态系统类型植被生产力及逐年生物量,估算各生态系统类型固定CO2和释放O2的能力,并根据生态学原理和生态经济学方法,运用碳税法、造林成本法和影子价格法,推算出各生态类型固定CO2和释放O2气体的生态、调节服务功能价值。研究表明,1985～2001年流域总生物量年均生物量和总体呈线性增加趋势。由于各种治理措施的实施和退耕还林(草)政策的正确导向,纸坊沟流域土地利用趋于合理,CO2/O2气体调节服务功能价值逐步增强,流域生态经济系统向良性演变。不同生态系统类型气体调节功能价值的估算为退耕还林(草)年限及生态补偿提供了科学决策依据。

黄土丘陵沟壑区不同植被类型的水土保持功能及养分流失效应

对黄土丘陵沟壑区安塞水土保持试验站3种草本、3种灌木、3种乔木、1种农田共计10种植被类型径流小区进行径流和侵蚀泥沙观测,并分别分析其养分含量,研究黄土丘陵区不同植被类型水土保持功能及养分流失效应。结果表明,乔、灌、草植被类型的水土保持功能相对农田较好,在径流和土壤养分流失方面相对农田较少。因此,该地区要注意建设和恢复草、灌植被,使之尽快起到水土保持作用,近而减少土壤养分流失。

纳豆的研究与应用

纳豆的研究与应用李宁（中国科学院沈阳应用生态研究所，１１００１５）纳豆是一种简单易得的有营养的优质发酵食品。它是将接种过纳豆菌（Ｂａｃｉｌｌｕｓｎａｔｔｏ）的蒸煮大豆在适当温度、湿度下发酵得到的。纳豆以其特殊的风味广受日本人的喜爱，它作为传统食物在日...

啤酒酿造中野生酵母的研究

啤酒酿造中野生酵母的研究吴文芳，张成刚，吕安国，李波（中国科学院沈阳应用生态所）金连武，蒋玲，孙喜春（辽宁铁岭市清河啤酒厂）所谓野生酵母，是指在啤酒酿造过程中出现的除培养酵母之外的所有酵母而言。威尔斯对野生酵母的定义是：任何未经严密选用与控制的酵母，...

平菇菌丝体对Cd、Pb及其复合污染的生长与富集响应

在PDA平板培养条件下,研究Cd、Pb及其复合污染对平菇菌丝体生长的影响以及平菇菌丝体对生长基质中Cd、Pb的生物富集作用.结果表明,在实验浓度范围内,菌丝生长势、菌落直径和菌丝体干重等均随着重金属浓度的增大而减弱(小)或降低.平菇菌丝体对Cd、Pb均具有生物富集作用,并且随着重金属浓度的增大菌丝体中重金属含量逐渐增大.Cd、Pb复合污染能促进平菇菌丝体对Pb的吸收,而抑制对Cd的吸收.

青海湖地区芨芨草草地土壤种子库的初步研究

选择青海湖地区的次生芨芨草草地为研究对象,以围栏内封育和围栏外自由放牧的草地做对照,研究了围栏内外土壤种子库的萌发状况、密度和数量、物种多样性,以及土壤种子库与地上植被的关系。结果表明,围栏内外土壤种子库的萌发趋势非常相似,但是萌发种子累计数量不同;围栏内外土壤种子库中萌发种子的平均密度分别为3660和2460粒·m-2,围栏内萌发种子数比围栏外提高了48.8%;围栏内外土壤种子库的物种多样性指数差异较大,围栏内外丰富度指数R1分别为17和13,R2为3.693和2.832,丰富度围栏内大于围栏外,多样性指数和丰富度指数具有相同的规律,均匀度指数围栏内外分别为0.812和0.857,则是围栏外大于围栏内。围栏内外地上植被群落组成存在显著差异,围栏内的封育草地的物种丰富度和多样性指数均大于围栏外的放牧草地,而均匀度指数则呈相反趋势。

中国首批濒危苔藓植物红色名录简报

初步报道了2004年上海中国苔藓植物多样性保护国际研讨会上通过的中国首批濒危苔藓植物红色名录。名录共计82种,其中藓类植物28科、47属、50种,苔类植物12科、26属、31种和角苔类植物1科、1属、1种。根据修订的IUCN/IAB标准,82种苔藓植物中,36种划为极危(CR),29种划为濒危(EN),17种划为易危(VU)。对中国首批濒危苔藓植物的地理分布特点、濒危原因及今后的保护行动也进行了初步讨论。

Purification and structure identification of hyaluronic acid

Polysaccharide produced by mutated strain of Streptococcus zooepidemicus was purified by the procedures including Savage method, quaternary ammonium compound precipitation, DEAE-cellulose(DE52) chromatography and Sephadex G-75 gel filtration. The structure of the purified polysaccharide has been characterized by means of chemical composition analysis, C-13 NMR spectrum, infrared spectrum and circular dichroism (CD). All the results showed that the purified polysaccharide was hyaluronic acid (HA). The single helix conformation of the purified HA was determined by Congo red experiment. The molecular weight of the HA was about 1.16x10(6)D, which was measured by viscosity method.

Context and conformation dictate function of a transcription antitermination switch

In bacteriophage, transcription elongation is regulated by the N protein, which binds a nascent mRNA hairpin ( termed boxB) and enables RNA polymerase to read through distal terminators. We have examined the structure, energetics and in vivo function of a number of N boxB complexes derived from in vitro protein selection. Trp18 fully stacks on the RNA loop in the wild-type structure, and can become partially or completely unstacked when the sequence context is changed three or four residues away, resulting in a recognition interface in which the best binding residues depend on the sequence context. Notably, in vivo antitermination activity correlates with the presence of a stacked aromatic residue at position 18, but not with N boxB binding affinity. Our work demonstrates that RNA polymerase responds to subtle conformational changes in cis-acting regulatory complexes and that approximation of components is not sufficient to generate a fully functional transcription switch.

Hydrothermal synthesis and crystal structure of sandwich-like heteropolymolybdophosphates

Sandwich-like heteropoly molybdochromophosphates of supermolecular compound [NH3(CH2)(6)NH3](2)H-3{Cr[Mo6O15(HPO4)(H2PO4)(3)](2)}. 4H(2)O has been hydrothermally synthesized and the single crystal structure has been determined by X-ray diffraction. The crystal data are has follows: triclinic, space group P (1) over bar a=12.156(2), b=12.809(3), c=13.530(3) Angstrom, alpha=102.46(3)degrees, beta=93.67(3)degrees, gamma=93.46(3)degrees, V=2046.9(7) Angstrom(3), Z=1, M-r=2768.69, D-c=2.246 g/cm(-3), F(000)=1337, mu=2.162 mm(-1). The structure has been refined to R=0.0666 and wR=0.1745 by full-matrix least-squares method. The title compound is composed of 1, 6-diaminohexane, water molecules, and {Cr[Mo6O15(HPO4)(H2PO4)(3)](2)}(7-) anion which consists of six oxygen atoms from two [Mo6P4] units with a sandwich-like transition metal atom Cr located at the center of symmetry.

卤代化合物的碳-13化学位移模拟

用人工神经网和多元回归方法对含２个碳的２１个卤代化合物的３５个化学位移进行计算机图谱模拟，结果表明，人工神经网络方法优于多元回归方法，同时此种方法处理这类问题有明显的优势。波谱模拟技术在有机化合物结构解析中是非常有用的方法。