间苯二酚改性酚醛树脂胶黏剂的研究

采用间苯二酚改性酚醛树脂胶黏剂,结果表明,P/R摩尔比对间苯二酚-苯酚-甲醛树脂胶合木的剪切强度影响不大,剥离率与P/R摩尔比呈线性关系.间苯二酚-苯酚-甲醛树脂胶合木的剪切强度≥6MPa,剥离率＜10％.     

无纺布增强装饰薄木的柔韧性研究

选用不同配比的聚乙酸乙烯酯乳液和脲醛树脂胶,制备无纺布增强装饰薄木,分析影响其柔韧性的主要工艺参数。结果表明,采用聚乙酸乙烯酯乳液胶,在涂胶量30g/m2、热压温度115℃、热压时间150s的条件下,无纺布增强装饰薄木的柔韧性最优,且横向抗拉强度显著提高,达到薄木自身强度的5～8倍,满足木制品异形贴面要求。     

金属氧化物催化下制备快速固化苯酚-尿素-甲醛树脂的性能

采用4种二价金属氧化物作为催化剂,探讨催化剂类别、加入阶段、加入量、甲醛添加量、氢氧化钠添加量等5个因素,对合成苯酚-尿素-甲醛(PUF)树脂性能的影响。结果表明:5个因素对PUF树脂凝胶时间、试件的胶合强度均有影响;与对照PUF树脂相比,采用优化工艺合成PUF树脂的热压时间和凝胶时间均明显缩短。     

Regional and Temporal Variations of Leptospira Seropositivity in Dogs in the United States, 2000–2010

Background

Previous studies have reported a seasonal increased risk for leptospirosis, but there is no consistent seasonality reported across regions in the United States.

Objectives

To evaluate and compare seasonal patterns in seropositivity for leptospirosis in dogs for 4 US regions (northeast [NE], midwest [MW], south‐central [SC], and California‐southern west coast [CS]).

Animals

Forty four thousand nine hundred and sixteen canine serum samples submitted to a commercial laboratory for microscopic agglutination tests (MAT) from 2000 through 2010.

Methods

In this retrospective study, positive cases were defined as MAT titers ≥1 : 3,200 for at least one of 7 tested serovars. Four geographic regions were defined, and MAT results were included in regional analyses based on hospital zipcode. A seasonal‐trend decomposition method for times series was utilized for the analysis. Monthly variation in the seropositive rate was evaluated using a seasonal cycle subseries plot and logistic regression.

Results

Two thousand and twelve of 44,916 (4.48%) samples were seropositive. Compared to seropositive rates for February, significantly higher monthly rates occurred during the 2nd half of the year in the MW (OR 3.92–6.35) and NE (OR 2.03–4.80) regions, and only in January (OR 2.34) and December (OR 1.74) in the SC region. Monthly seropositive rates indicative of seasonality were observed earlier in the calendar year for both CS and SC regions.

Conclusions and Clinical Importance

Seasonal patterns for seropositivity to leptospires differed by geographic region. Although risk of infection in dogs can occur year round, knowledge of seasonal trends can assist veterinarians in formulating differential diagnoses and evaluation of exposure risk.     

嘉陵江三江汇合区段的沙量平衡及控制三峡水库泥沙措施探讨

根据嘉陵江，涪江和渠江３个水文站的沙量平衡计算表明，该区间河段的输沙模数明显增大。利用邻近地区输移比值，估算子该区段流流域的侵蚀模数，参照重庆市采用的土壤侵蚀模数综合值分析。认为川东平行岭谷区的重庆市用中等侵蚀程度评估水土流失程度过于保守。著者根据区间流域产沙量分析，并参照国家标准，认为重庆市用强度过于保守。著者根据区间流域产沙量分析，并参照国家标准，认为重庆市用强度侵蚀来评价土壤侵蚀是适宜的。文     

纳米材料改性环氧树脂结构胶粘接强度的研究

采用纳米二氧化硅、纳米碳酸钙和有机蒙脱土3种纳米材料对环氧树脂结构胶进行改性,改性后环氧树脂结构胶的粘接强度得到显著提高.实验表明:含5%纳米二氧化硅、20%纳米碳酸钙和10%蒙脱土时,环氧树脂结构胶的钢钢抗剪强度比基体分别提高了23.2%,39.3%和63.0%.纳米二氧化硅和纳米碳酸钙的组合产生叠合效应使结构胶的钢钢抗剪强度在25℃下固化达29.3 MPa.XRD衍射实验表明,有机蒙脱土和环氧树脂能进行插层复合,其晶面间距从2.4 nm撑开至8.8 nm以上.SEM实验表明3种纳米材料在基体中能诱发大量银纹,是结构胶粘接强度得到提高的主要原因.     

陇中黄土高原丘陵区建设水土保持型生态农业的经验及建议

介绍了陇中黄土高原丘陵区建设水土保持型生态农业的意义及经验,提出该区水土保持性生态农业可持续发展的建议是:必须坚持因地制宜的原则;必须以水资源的承载能力为出发点;充分发挥生态系统的自我修复功能;注重发展灌木林.     

郑州西南绕城高速公路不同时期生态系统服务价值研究

根据黄土沟壑地带高速公路建设不同时期生态系统特征和生态服务功能的内涵,选择了水土保持、固定CO2、释放O2、滞尘、吸收有害气体、营养元素循环等指标,采用物质量和价值量相结合的评价方法,使用市场价值法、影子工程法、生产成本法、机会成本法研究了郑州西南绕城高速公路不同时期生态系统服务功能经济价值。结果表明:研究区建设前农业生态系统服务功能价值平均每年为424.2万元,建设期间为197.5万元,生态防护后为484.6万元。生态防护前后生态服务价值的差异极为显著,防护后生态服务价值超过原农业生态系统价值。