清塘净对鱼类等水生生物急性致毒的研究

清塘净对鱼类等水生生物毒性强，毒力降解速度较快，是好的清塘药物。对黄鳝等水生生物９６ｈ的ＬＣ５０及安全质量浓度分别为：黄鳝２．４１ｍｇ／Ｌ和０．２４１ｍｇ／Ｌ；鲤鱼苗０．３８ｍｇ／Ｌ和０．０３８ｍｇ／Ｌ；草鱼苗０．４１ｍｇ／Ｌ和０．０４１ｍｇ／Ｌ；大型蚤０．５２ｍｇ／Ｌ和０．０５２ｍｇ／Ｌ；湖螺２．３３ｍｇ／Ｌ和０．２３３ｍｇ／Ｌ；泥鳅３．０４ｍｇ／Ｌ和０．３０４ｍｇ／Ｌ。     

Development of an assay to determine the bioavailability of potassium in feedstuffs for the young pig

A series of four trials was conducted to verify the published requirement of .26% total K in the diet and to identify response variables useful in an assay of the bioavailability of K in feedstuffs for the young pig. Purified diets were supplemented with K at four levels as KC2H3O2 in three trials and as KHCO3 in the fourth trial. In the first three trials, the requirement was estimated by least-squares analysis of a linear-plateau response of average daily gain. Additional measures in each trial were taken for linear response to dietary K levels. The three estimates of K requirement obtained were .30, .33 and .26% total K in the diet. These three estimates were not found to be inconsistent with the published value of .26% total K in the diet. Various urinary and hematological measures also were examined during the four trials for linear response to dietary K levels. Plasma K was the only hematological response to show a significant linear relationship to dietary K levels. Urinary K concentrations and daily excretion showed a highly significant linear response to dietary K levels. Based on these results, a K bioavailability assay using urinary K measures as the primary response variable and plasma K as the secondary response variable seems the most promising.     

On the fracture morphology in wood

Summary Structural changes in spruce and aspen wood samples subjected to axial compression were examined by means of the scanning electron microscope. For comparison, macroscopic model experiments were carried out on tube-shaped samples made of paper so as to represent segments of fibriform xylem cells. The results show that there are fracture patterns characteristic of wood in general and others characteristic of the species of wood. The phenomena characteristic of wood in general are prevalent at the cellular level and in the fracture behaviour of the cell wall layers and perforations. The characteristics of the various species of wood dominate at the level of the growth rings and are decisively influenced by the composition and arrangement of the tissues. The model experiments show that the failure morphology of the individual cells of the xylem may be explained to some extent by their geometry.     

Characterization of proanthocyanidin in hot water extract isolated from <Emphasis Type="Italic">Pinus radiata</Emphasis> bark

Proanthocyanidins (PAs) in the hot water extract prepared from Pinus radiata bark were isolated by a Sephadex LH-20 chromatography. The PAs were characterized using UV/Visible, FT-IR and ¹³C nuclear magnetic resonance (NMR) spectroscopic techniques, matrix-assisted laser desorption/ionization time of flight (MALDI-TOF) mass spectrometry (MS), and gel permeation chromatography (GPC) analysis. Bate-Smith acidic alcoholysis and FT-IR spectrum of the PAs indicated the predominant presence of the procyanidin (PC) structure. The ¹³C NMR spectrum revealed that the PAs comprise PC (94%) together with a small amount of prodelphinidin (PD, 6%), and also that they contain the higher trans configuration rather than the cis configuration of C2–C3. The MALDI-TOF MS results obviously proved the presence of PD units, but the maximum degree of polymerization (DP) was limited to octamer. The average molar mass (Mw, Mn), polydispersity (Mw/Mn), and DP of the pine bark PAs were 3,800 (Mw), 1,200 (Mn), 3.2, and 13, respectively.     

Chemical Characterization of Rain and Fog Water in the Cervenohorske Sedlo (Hruby Jesenik Mountains, Czech Republic)

Field study at the Cervenohorske sedlo (1,013 m a.s.l.) (Hruby Jesenik Mountains, the Czech Republic, Central Europe) during 1999–2002 has been conducted in order to analyse the chemistry of rain/snow water using bulk and throughfall collector and fog/cloud water using modified passive Grunow collector. Fog water input to coniferous forest (Picea abies) was quantified using canopy balance method. For all samples pH, and the concentrations of $ {\text{NH}}^{{\text{ + }}}_{{\text{4}}} $ , Ca²⁺, K⁺, Mg²⁺, Na⁺, Cl^?, $ {\text{NO}}^{{\text{ - }}}_{{\text{3}}} $ , and $ {\text{SO}}^{{{\text{2 - }}}}_{{\text{4}}} $ were measured. The volume-weighted mean pH value varied from 4.92 to 5.43 in open bulk precipitation, from 4.30 to 4.71 in throughfall and from 4.66 to 5.23 in fog water. The fog droplets generally contain higher ion concentrations than rainwater. The related enrichment factors lie between 1.1 and 10.7 for the relevant species. The fog samples exhibit higher concentrations of $ {\text{NO}}^{{\text{ - }}}_{{\text{3}}} $ and $ {\text{NH}}^{{\text{ + }}}_{{\text{4}}} $ as compared to the bulk samples during 2000–2002. $ {\text{NO}}^{{\text{ - }}}_{{\text{3}}} $ are 5.7–10.7 times more concentrated in fog water and $ {\text{NH}}^{{\text{ + }}}_{{\text{4}}} $ are 3.4–7.2 times more concentrated in fog water. These differences may result from the height and characteristics of formation of the droplets. Based on canopy balance method, the annual fog water inputs were estimated to be 22 and 19% of rain and snow annual amounts in 1999 and 2000, respectively. For $ {\text{NO}}^{{\text{ - }}}_{{\text{3}}} $ , $ {\text{NH}}^{{\text{ + }}}_{{\text{4}}} $ , and $ {\text{SO}}^{{{\text{2 - }}}}_{{\text{4}}} $ , the contribution of fog deposition in total (bulk + fog) deposition is estimated as 54, 47, and 42%, respectively.     

池塘培育草鱼种关键技术

1999年6月9月，使用池塘3口（面积1．21hm^2)培育草鱼种。经87d，总产10571kg,其中草鱼种6249kg，出塘率92．5％，饵料系数1．57；鲢、鳙鱼种4322kg，出塘率71．3％。总产值7．35万元，利润4．15万元。同时对草鱼夏花至秋片不同生长阶段蛋白质需求量，以及颗粒饲料粒径与鱼口裂大小关系等进行了试验。     

Improvement of foreign gene expression in transgenic rice ( Oryza sativa L. ) by matrix attachment regions (MARs)

Matrix attachment regions or matrix associated regions (MARs) were special DNA sequences in chromatin of eukaryotic cells that tightly associated with the nuclear matrix or scaffold in vitro after a combination of nuclease digestion and extraction. They were also called scaffold attachment regions (SARs) .     

Extending the postharvest life of carnations with nitric oxide—comparison of fumigation and in vivo delivery

The ability of nitric oxide (NO) to extend the postharvest life at 20 °C of carnations (Dianthus caryophyllus L. cv. White-Sim) was investigated using delivery by gas-based fumigation and in vivo release via a solution containing the NO donor compound 2,2′-(hydroxynitrosohydrazino)-bisethanamine (DETA/NO). Treatment with NO gas in air at 1 and 5 μl l⁻¹ produced about a 30% increase in postharvest life while DETA/NO applied in solution at 10 mg l⁻¹ extended postharvest life by about 50% when dissolved in water. For flowers, use of solid delivery appears to offer a more convenient and more effective method of NO treatment than gaseous fumigation to extend postharvest life.     

鲜食糯玉米农艺性状与鲜穗产量的灰色关联度分析

以正在参加黄淮海国家糯玉米区域试验的19个新品种为材料，利用灰色关联度分析方法，对11个农艺性状与鲜穗产量进行了关联度分析。结果表明，糯玉米农艺性状与产量关联度的大小依次为穗粗﹥穗行数﹥穗长﹥株高﹥收获期﹥行粒数﹥轴粗﹥穗位高﹥鲜百粒重﹥鲜出籽率﹥秃尖长。穗粗、穗行数、穗长、株高是影响糯玉米鲜穗产量的主要因素，而鲜穗百粒重、鲜出籽率、秃尖长度对产量影响则较小。但影响鲜穗产量的主要因素在不同产量水平品种中存在一定差异