入世后国有大中型种子企业发展的思考

发展农业生产、提高农产品效益的最有效最经济的途径是种子.故此我们需要从战略的高度来关注种子公司的发展.那么,在我国加入WTO(世贸组织)之后,我国的种子公司如何面对新的机遇与挑战,如何在国际竞争中立于不败之地,如何发展和壮大中国的种子产业,值得深思.     

建筑物的机械排烟

本文作者从实际经验出发,详细阐述了建筑物的机械排烟原理及设计施工,管理中的各项注意事项。     

Propagation techniques on root turion sprout browse ofPopulus davidiana Dode

The root segments selected from dominant trees ofPopulus davidiana Dode were taken as reproductive material and were buried in different depths to carry out the reproduction of root turion sprout. The affecting factors of gemination rate, survival rate, and height growth for cutting wood of root sprout were comparatively analyzed. The results showed that the best suitable substrate for burying root is pearlite, with a germination rate of 15.16%. 3–4-cm root segments has the highest rate of germination (12.4%). The mixture of sand and soil (2∶1) is the best cutting substrate, with a survival rate of 81.3%, while as to height growth of cutting wood, the mixture of turfy and soil (1∶1) is the best. The cutting woods selected from different positions of stem show difference in height growth. The cutting wood from top stem is higher obviously than those from middle or low stem. Biography: XING Ya-juan (1969-), female, assistant researcher in Forest Research Institute of Heilongjiang Province, Harbin 150040, P. R. China. Responsible editor: Song Funan     

The immunohistochemical detection of Mycoplasma bovis and bovine viral diarrhea virus in tissues of feedlot cattle with chronic, unresponsive respiratory disease and/or arthritis.

The purpose of this study was to determine the frequency of selected pathogens in the tissues of a group of feedlot cattle with chronic disease (most often respiratory disease and/or arthritis). Samples of lung and joint tissues from 49 feedlot animals that had failed to respond to antibiotic therapy were tested by immunohistochemical staining for the antigens of Mycoplasma bovis, Haemophilus somnus, Pasteurella (Mannheimia) hemolytica, and bovine viral diarrhea virus (BVDV). Mycoplasma bovis was demonstrated in over 80% of cases, including in 45% of joints and 71% of lungs tested. Mycoplasma bovis was the only bacterial pathogen identified in the joints. Haemophilus somnus and Pasteurella (Mannheimia) haemolytica were found in 14% and 23% of cases, respectively, and were confined to the lungs in all instances. Infection with BVDV was demonstrated in over 40% of cases. Mycoplasma bovis and BVDV were the most common pathogens persisting in the tissues of these animals that had failed to respond to antibiotic therapy.     

枣品种选择试验研究

1997～1999年对收集引进的22个枣品种进行生长和结果情况调查及物候期定点预测，以大荔圆枣为对照，从丰产性、品质、抗性（抗裂果）、单果重、结果整齐度5个方面进行综合评比，筛选出适宜我省发展的不同用途的枣树优良品种12个，为黄土高原红枣产业化发展提供了品种依据。     

饥饿、季节及性别对大鲵肌肉、肝脏生化成分的影响

季节会影响到大鲵肌肉的脂肪及钙的含量,肝脏的脂肪、钙及游离氨基酸的含量,饥饿对肌肉的酸化成分不产生影响,但饥饿程度的增加,会对肝脏脂肪无氮浸出物及游离氨基酸产生影响;繁殖前雌性大鲵的肌肉肝脏的肪肪含量均高于雄性的。     

饲用木聚糖酶的研究进展

木聚糖酶是一类可将木聚糖降解成低聚糖和木糖的复合酶系。对木聚糖酶的研究早在上世纪60年代就已开始，已经从不同来源的微生物中分离到大量的不同类型不同功能的木聚糖酶。研究得较为清楚的有里氏木霉、黑曲霉和浅青紫链霉菌等等。最近10几年，随着生物技术的不断发展和进步．特别是基因工程技术和蛋白质工程技术的广泛应用，对木聚糖酶的了解更加深入，已经分离出多种木聚糖酶基因，并已进行工业生产。木聚糖酶在饲料工业、制浆造纸工业、食品工业和能源工业中都显示出广阔的应用前景，已经引起了广泛关注。     

关于我国海水网箱养鱼发展现状与危机分析及可持续发展的探讨

我国海水网箱养鱼发展现状是以个体联合体生产经营为主体的低技术水平的数量规模化，众多传统港湾已形成了大范围的严重超负荷养殖状态，其对环境巨大的污染力引发鱼病猖獗和频受赤潮侵袭，已面临严峻的养殖环境危机。本文综合分析了我国海水网箱养鱼的发展现状与负面效应及其现状危机，并初步进行了危机根源和可持续发展的讨论分析。     

Enhancement of sulfide auto-oxidation by metal ion in artificial seawater and a seawater which is a possible source of aoshio

SUMMARY: Aoshio is hypoxic milky blue-green seawater observed in some eutrophic bays. Previous studies have shown that colloidal sulfur causes the coloration and that the source of aoshio water is attributed to coastal anoxic bottom water. Occurrences of aoshio have been reported in limited areas of coastal seawater, although hypoxic transparent water seems rather universal. Promotion in auto-oxidation of sulfide by metal ions in seawater was investigated to explain the occurrences of aoshio. Artificial seawater containing 10 μM metal ion was assayed for the sulfide oxidation rate. The velocity constant which represents the oxidation rate within the initial 30 min and the amount of reacted sulfide in 2 h were determined by oxygen monitoring and sulfide quantification, respectively. Fe²⁺ and Cu²⁺ enhanced the initial 30 min reaction. Fe²⁺, Fe³⁺ and Ni²⁺ increased the amount of reacted sulfide in 2 h, forming whitish turbid water. Seawater from a suspected source of aoshio water was also assayed for the auto-oxidation rate of sulfide. The oxidation rate in water from 12 m depth was 13–19 times higher than the artificial seawater without an addition of heavy metal ions. More than 15% of the oxidation rate in 12 m deep seawater was explained by dissolved iron in the seawater.     

比格犬人工感染埃立克体病的临床研究

为了表述比格犬感染埃立克体（Ehrlichia)后的临床表现，用已确证为Ｅ．platys和Ｅ．canis混合感染的犬血对５条比格犬进行了人工感染，并对临床和血液学变化进行了观察。埃立克体病的潜伏期为６－２９天，其后的临床表现为急性发热、眼结膜苍白、厌食、精神沉郁、体重严重减轻、腹泻带血、多处有淤血斑点出现、６－４５天内全部死亡。血液学变化显示血红蛋白和白细胞明显减少（Ｐ＜０．０１，Ｐ＜０．０５）。由此可见，比格犬对２种埃立克体（Ｅ.canis和Ｅ．platys）混合感染的性很高，严重的临床表现与美国学者普遍认为的亚临床状态相左，这可能是中国Ｇzh981株（Ｅ．platys)和Ｇzh982株（Ｅ．casnis)与国外株在毒力上的差异所致。