热处理木材吸湿性及尺寸稳定性研究

以毛白杨(Populus tomentosa)、云杉(Picea asperata)和樟子松(Pinus sylvestris)为试验材料,通过蒸汽法进行热处理后,与未处理材相比,毛白杨的吸湿率降低28.8%~41.9%;弦向吸湿膨胀率降低20.9%~51.7%。云杉吸湿率降低19.5%~31.4%;弦向吸湿膨胀率降低22.2%~50.8%。樟子松吸湿率降低27.7%~34.4%;弦向吸湿膨胀率降低22.8%~50.0%。结果表明,热处理能够极大地降低木材的吸湿性,同时提高木材的尺寸稳定性,解决了室外用木材的吸水性强及尺寸不稳定性。     

Chemical modification of the photoluminescence quenching of porous silicon

The photoluminescence of porous silicon can be quenched by adsorbates, and the degree of quenching can be tuned by chemical derivatization of the porous silicon surface. Thus, as-prepared porous silicon has a hydrophobic, hydrogen-terminated surface, and the photoluminescence is strongly quenched by ethanol and weakly quenched by water. Mild chemical oxidation (iodine followed by hydrolysis) produces a hydrophilic porous silicon surface. Photoluminescence from this hydrophilic material is quenched to a lesser extent by ethanol and to a greater extent by water, relative to the original surface. This demonstrates that the visible luminescence from porous silicon is highly surface-sensitive, and the surface interactions can be tuned by specific chemical transformations.     

舟山港船舶溢油事故风险评估研究

国内海上油运的迅速发展将导致船舶溢油事故风险逐年增大,科学的船舶溢油事故风险评估作为船舶溢油事故防控工作的重要方面也越来越受到重视。通过对我国以往船舶溢油事故的综合分析,借助国内外溢油事故数据和科学的评估方法,对舟山港的溢油事故发生概率和溢油量进行了预测和评估。得出的结论和建议将为船舶溢油事故应急能力建设提供参考和初步依据。     

两种土壤中钙镁磷钾向根系的运移机理

 于人工气候室盆栽试验研究了黄绵土和垆土中钙镁磷钾向根系运移中质流和扩散的相对重要性。结果表明，小麦、玉米和大豆根-土系统Ca、Mg的运移以质流为主，质流养分量为作物吸收量的数倍至数十倍；P、K的运移以扩散为主，扩散对吸收量的贡献率P通常为90%以上，且此贡献率基本不受作物种类、生育期及土壤水分、大气蒸发力等环境条件的影响；苗期扩散K占吸收量的90%以上，但在土壤含水量高的小麦生长盛期，其扩散贡献率可降低到70%左右，说明作物钾供应质流时常也有较大的作用。     

高CO_2浓度条件下农田土壤有机质的化学稳定性研究

大气CO2浓度升高显著增加作物生物量,从而使进入土壤的有机碳增加,这势必会影响土壤碳的稳定和积累。采取利用化学方法获得的具有不同化学稳定性的有机物,间接地研究大气CO2浓度升高以后通过直接影响秸秆生物量和化学成分对土壤碳变化的影响。结果显示,相对于对照处理:高CO2浓度处理使土壤经Na2S2O8化学氧化后的抗氧化部分,在LN、NN和HN水平下,分别增加16.4%、21.7%和降低3.8%;使土壤经硫酸水解后的第一组分分别降低2.2%,增加9.5%和7.5%,第二组分分别增加4.7%、17.6%和降低4.9%,第三组分分别增加7.3%,降低4.2%和2.6%。表明土壤有机质的化学稳定性有所增加,可能与高CO2浓度条件下向土壤输入的有机质量及化学组成有关,且受N水平的影响较大。     

基于CA模型的珠江三角洲基塘景观破碎化分析及其模拟

在对珠江三角洲传统基塘区2000、2006、2011年基塘景观破碎化特征分析的基础上,运用LogisticCA模型开展了传统基塘区2020年的基塘景观的模拟研究。结果表明,2000~2011年,传统基塘区基塘面积减少了46.65%,斑块数量由139个增加到1 072个,平均斑块面积减少了97.12%,反映了斑块由集中成片发展成为破碎的状态;形状指数增加了36.23%,在人类活动的干预下,基塘斑块形状趋于复杂化;边缘密度减少了88.57%,反映了单位面积上斑块数量增多了;平均最近邻近距离变化幅度最大,减少了99.75%,说明相同类型的斑块之间的距离变近,呈团聚分布。根据2020年模拟结果 ,基塘面积减少53.38%,基塘斑块数量增加为2 045个,平均斑块面积减少82.33%,形状指数增加22.12%,边缘密度增加80.74%,平均最近邻近距离减少86.00%,基塘破碎化的程度有所减缓。研究结果可为传统基塘区生态服务功能的延续、农业生态系统的恢复和区域生态经济的可持续发展提供参考。     

滨海沙地木麻黄基干林带不同更新方式综合评价研究

运用密切值法,于2002年对滨海沙地木麻黄基干林带5种更新方式进行综合评价,结果表明．间隔带状采伐更新方式优于林下套种更新方式,间隔带状采伐更新其生态、社会、经济及综合效益均高于林下套种更新方式。在间隔带状采伐更新中,以窄采伐带为优。林下套种更新方式中,林带渐伐后林下更新方式其生态、社会、经济及综合效益均比直接在林下套种更新方式高。对于只能进行林下套种更新的木麻黄基干林带．根据林带郁闭度作适当渐伐调整并选用适应于沿海沙地生长具有一定耐荫性的树种在林下套种,可使其综合效益得到明显提高。     

枣树专用叶面肥施肥技术及其肥效

采用正交试验设计对枣树专用叶面施肥技术及其肥效进行了研究。对不同时期果吊比和单果重分析结果表明,花明喷施枣树专用叶面肥可显著提高红枣座果率,喷肥1次较对照（喷水）果吊比提高59.3%;幼果期喷施具有保果、促进幼果生长发育之功效,喷肥1次较对照果吊比提高19.2%,单果重增加12.7%;膨个期喷施可促进枣果膨大,喷肥1次较对照单果重增加6.4%。单株产值多重比较分析结果表明,枣树专用叶面肥的最佳施肥方案为花期1次,幼果期1次,膨个期2次。最佳施肥方案与对照相比,单株产量提高53.6%,单株产值提高64.3%。     

新疆水资源短缺原因分析

根据新疆水资源分布特征及利用状况，分析了新疆水资源短缺的5种基本类型（资源性，工程性，设施性，管理性和污染性），以及水资源短缺的原因，认为新疆水资源短缺是自然因素与人为因素共同作用的结果。解决资源性缺水的根本出路是大规模和大跨度的调水工程。疆内跨流域调水，流域内控制性调蓄工程与灌区改造和配套工程的建设是解决工程性与设施性缺水的重点，管理性缺水要从流域水资源统一调配，科学管理着手，并注重治理污染性缺水的加重和蔓延。     

Dopamine: mediator of brain polysome disaggregation after L-dopa

The disaggregation of brain polysomes which is produced by giving large doses of (L)-dopa to rats is not reproduced by administering its metabolite, 3-O-methyldopa, by giving D-dopa, which also depletes the brain of S-adenosylmethionine but is not converted to catecholamines, or by giving the L-dopa after a decarboxylase inhibitor. Polysome disaggregation is potentiated by the prior administration of a monoamine oxidase inhibitor, indicating that formation of a catecholamine is an obligatory requirement. These observations suggest that the mechanism by which L-dopa disaggregates brain polysomes involves its conversion to dopamine within the majority of brain cells.     

拟南芥atcwinv1基因T-DNA插入纯合突变体PCR鉴定及表型观察

以拟南芥atcwinvl 基因T-DNA插入纯合突变体和野生型植株为材料,比较研究了2种基因型植株在营养期和生殖期的形态差异.结果表明:拟南芥atcwinvl 基因T-DNA插入纯合突变体(简称突变体)较野生型萌发率平均下降5.88个百分点;突变体在44 d抽薹,较野生型延后4d;分支数平均4支,较野生型下降20.84...     

西瓜、水稻根分泌物及酚酸类物质对西瓜专化型尖孢镰刀菌的影响#br#

 【目的】探讨西瓜、水稻根分泌物及其中的酚酸类物质对西瓜专化型尖孢镰刀菌(Fusarium oxysporum f. sp. niveum,FON)的影响,阐释西瓜枯萎病的发生和西瓜/旱作水稻间作系统改善西瓜连作枯萎病的机理。【方法】营养液培养法收集西瓜根分泌物(REW)和水稻根分泌物(RER),研究其对FON生长的影响;HPLC法分离鉴定REW和RER中的酚酸类物质,并通过外源添加法研究该类物质对FON生长的影响。【结果】REW能显著促进FON孢子萌发和产孢,与对照相比,1.0 mL和5.0 mL 的REW对FON孢子萌发的促进率分别为46.9%和59.2%;在0.1 mL至2.0 mL范围内,REW对FON产孢的促进率从10.8 %逐渐增加到84.6 %;而RER能显著抑制FON孢子萌发和产孢,1.0 mL和5.0 mL RER对FON孢子萌发抑制率分别为14.3 %和6.1 %;并在0.1 mL至2.0 mL范围内,对该菌产孢的抑制率由4.6%增至37.5%。在REW和RER中同时检测到水杨酸、对羟基苯甲酸和邻苯二甲酸,而阿魏酸和香豆酸分别单独存在于REW和RER中;且RER中以香豆酸含量最高(占总量的37.9%);其酚酸总量是REW的1.4倍。综合FON孢子萌发、产孢能力和菌丝生长三项测定指标,香豆酸的抑菌效果最显著,抑制率分别为9.1%—70.5%、24.1%—100.0%和2.5%—47.5%,其次是水杨酸;而阿魏酸、对羟基苯甲酸、邻苯二甲酸对FON孢子萌发、产孢有不同程度的促进作用,以阿魏酸最为突出,浓度为40—160 mg•L-1时促进率分别为28.6%—114.3%和17.7%—54.8%。【结论】西瓜根分泌物对FON有刺激作用而水稻根分泌物对FON却具有抑制作用,这为阐释西瓜/旱作水稻间作系统改善西瓜连作枯萎病提供了理论依据。     

不同沟麦种植方式小气候效应的研究

本文利用晴天实测资料,对沟麦和畦麦的小气候效应进行了研究。结果表明：沟麦与畦麦相比较,①沟麦对光合有效辐射的吸收率上层（６０～８０ｃｍ）减小７％～１４％,下层（０～４０ｃｍ）增加３％左右;②动力速度增加１５％～３１％,湍流交换系数增加３％～１４％,里查逊数减小１３％～６３％;③ＣＯ２通量增加９％～１６％,０～２０ｃｍ土层的土壤湿度增加０２％～２％。     

水稻恶苗病菌对使百克、多菌灵的抗性遗传研究

采用使百克、多菌灵对病原菌直接进行诱变,获得相应的抗性菌株,对其抗性遗传规律进行研究.结果表明,安徽省水稻恶苗病菌对多菌灵已产生了中等程度的抗药性,对使百克的抗性较低.通过多菌灵、使百克诱变均都能产生抗性菌株,但就抗性增长速度而言,多菌灵远高于使百克.产生抗性的突变菌株后代表现说明,多菌灵的抗性突变菌株遗传较稳定.单剂诱变的抗性菌株致病性高于复配剂诱变菌株和敏感菌株.     

沼液配方肥对香蕉产量、品质及香蕉园土壤质量的影响

笔者以香蕉(Musa nana Lour.)为材料,进行沼液配方肥的肥效试验并研究沼液配方肥对香蕉产量、果实品质和试验地土壤性质的影响。结果表明:施用沼液配方肥可以提高香蕉产量、果实品质,改善海南砖红壤,提高酸性土壤p H、增加土壤养分含量。与施用常规化肥相比,施用沼液配方肥的香蕉果指长增长5.59%、果指围增粗11.01%、每梳个数增加3.21%、单株产量提高了4.09%,香蕉果实蛋白质增加10.67%、可溶性含糖量6.66%、维生素C增加3.32%,不同土层土壤有机质增加2.98%~3.93%、碱解氮增加2.25%~17.07%、有效磷增加5.59%~18.64%、速效钾增加25.20%~39.20%。对香蕉施用沼液配方肥不仅提高作物其产量和果实品质,而且可改善种植地土壤的状况。试验结果可为沼液配方肥深度研发、推广及其海南土壤性质改良提供依据。     

Hemagglutination by fava bean extract inhibited by simple sugars

Hemagglutination by extract of fava bean was inhibited by 5-percent d-glucose, d-fructose, or maltose, but not by 5-percent d-galactose or lactose. Failure to inhibit seems to reflect the presence of a hydroxyl group at the carbon No. 4 position. Hemagglutination was enhanced by dextran of high molecular weight, but not by dextran of low molecular weight. The finding supports the hypothesis that large molecular size explains the enhancement by gum acacia of hemagglutination by fava bean.     

Protecting brains, not simply stimulating minds

Curricular enhancements in early childhood education that are guided by the science of learning must be augmented by protective interventions informed by the biology of adversity. The same neuroplasticity that leaves emotional regulation, behavioral adaptation, and executive functioning skills vulnerable to early disruption by stressful environments also enables their successful development through focused interventions during sensitive periods in their maturation. The early childhood field should therefore combine cognitive-linguistic enrichment with greater attention to preventing, reducing, or mitigating the consequences of significant adversity on the developing brain. Guided by this enhanced theory of change, scientists, practitioners, and policy-makers must work together to design, implement, and evaluate innovative strategies to produce substantially greater impacts than those achieved by existing programs.     

抑制稗草生长的木霉菌REMI转化子构建与功能初探

创制新的木霉菌突变株,为筛选新的抑草类化合物奠定基础。通过REMI插入突变技术,以Trichoderma atrovirideT23为出发菌,进行了REMI转化子构建。对得到的转化子进行了PCR检测,分别利用抗潮霉素和氨苄青霉素基因为引物进行特异性扩增,并对发酵产物细分为分生孢子、超声波PBS法破碎孢子和发酵液,分别对稗草生长的生物活性进行测试。获得了18个转化子,通过继代培养和PCR扩增,证明线性pV2质粒DNA已成功插入木霉菌基因组。从REMI创制的木霉菌突变株库中,筛选出8株有抑草活性转化子(TaA2、TaB3T、aB7、TaE2、TaE8T、aH8、TaJ6和TaJ9),其发酵液具有抑制稗草的活性,并对水稻生长安全。经测试发酵产物对稗草生长的生物活性,获得了具有抑草活性及稳定性均理想的转化子TaB3。REMI方法所创造的转化子可较高效地筛选出具有抑草功能的突变体。     

Ethanol inhibits NMDA-activated ion current in hippocampal neurons

The ion current induced by the glutamate receptor agonist N-methyl-D-aspartate (NMDA) in voltage-clamped hippocampal neurons was inhibited by ethanol (EtOH). Inhibition increased in a concentration-dependent manner over the range 5 to 50 mM, a range that also produces intoxication. The amplitude of the NMDA-activated current was reduced 61 percent by 50 mM EtOH; in contrast, this concentration of EtOH reduced the amplitude of current activated by the glutamate receptor agonists kainate and quisqualate by only 18 and 15 percent, respectively. The potency for inhibition of the NMDA-activated current by several alcohols is linearly related to their intoxicating potency, suggesting that alcohol-induced inhibition of responses to NMDA receptor activation may contribute to the neural and cognitive impairments associated with intoxication.     

Escape of intracellular Shigella from autophagy

The degradation of undesirable cellular components or organelles, including invading microbes, by autophagy is crucial for cell survival. Here, Shigella, an invasive bacteria, was found to be able to escape autophagy by secreting IcsB by means of the type III secretion system. Mutant bacteria lacking IcsB were trapped by autophagy during multiplication within the host cells. IcsB did not directly inhibit autophagy. Rather, Shigella VirG, a protein required for intracellular actin-based motility, induced autophagy by binding to the autophagy protein, Atg5. In nonmutant Shigella, this binding is competitively inhibited by IcsB binding to VirG.