几种农药对桑椹小粒性菌核病的防治效果试验

桑椹菌核病是果用桑树的重要病害,为高效、安全控制该病对桑果生产的危害,进行了大田农药防治筛选试验。结果表明,70%甲基托布津可湿性粉剂500倍液、50%多菌灵-硫磺粉剂500倍液和1 000倍液对桑椹小粒性菌核病具有较好的防治效果,且对桑叶和桑椹无明显药害;70%甲基托布津粉剂1 000倍液、25%吡唑醚菌酯乳油1 500倍和3 000倍液以及40%嘧霉胺粉剂1 000倍液也有一定的防治效果。     

电机护环钢在硝酸盐溶液中应力腐蚀开裂的控制过程研究

本文在文献［１］基础上，运用金相，电化学方法研究了５０Ｍｎ１８Ｃｒ４电机护环钢依照ＱＨＪ－７９试验标准在硝酸盐介质中应力腐蚀开裂（即ＳＣＣ）的性质，结果指出，此体系中ＳＣＣ的控制过程为阳极溶解。     

Statistical tools for determining appropriate selection of regression models for analysis of environmental fate datasets

BACKGROUND: In the NAFTA regulatory community, a currently consistent methodology used to estimate dissipation times for environmental fate data is not applied. RESULTS: This work demonstrates through a case study that the inappropriate use of pseudo-first-order regression models can result in inaccurate estimates of soil degradation rates, and it proposes some statistical tools that can be used to identify an appropriate statistical model to fit a particular environmental fate dataset. Diagnostic procedures have been proposed to identify the appropriate scale, and statistical testing procedures have been proposed to select the appropriate model within that scale. CONCLUSION: Results from this work demonstrate that, unless the proposed diagnostic and statistical procedures are used, inaccurate estimates of dissipation times may result.     

Chemically and genetically immunocompromised mice are not more susceptible than immunocompetent mice to infection with Cryptosporidium muris

The prevailing paradigm is that immunosuppressed individuals are more susceptible to infection and are at higher risk of infection from Cryptosporidium oocysts if present in drinking water. To test this hypothesis, three immune conditions were examined: genetically immunocompromised T cell deficient CD-1 nude mice, B and T cell deficient Fox Chase CB-17/IcrClB SCID mice, and chemically immunosuppressed C57Bl/6 mice. Chemical immunosuppression was induced with a single subcutaneous injection of methylprednisolone acetate (MPA) at 600 mg/kg. The MPA immunosuppressed C57Bl/6 mice were characterized by a sustained decrease in circulating CD3, CD4 and CD8 T-lymphocytes of greater than 80% and a similar decrease in B-lymphocytes. A sharp rise in circulating mature segmented neutrophils followed MPA injection, dropping sharply after 10-14 days, mirroring the decrease in lymphocytes. The cessation of oocyst production after MPA was not accompanied by a radical rise in circulating CD3 or CD4 T-lymphocytes, but rather a rise in CD8 T-lymphocytes. The ID50 for the MPA immunosuppressed C57Bl/6 mice was 122 oocysts, whereas the ID50 for the C57Bl/6 immunocompetent group was 44. The genetically immunocompromised mice showed similar differences. The ID50 for CD-1 nude mice was 166 oocysts compared to 64 in CD-1 immunocompetent mice. For Fox Chase CB-17/IcrClB SCID and the immunocompetent CB-17 mice, the ID50's were 83 and 60 oocysts, respectively. These results suggest that the lack of an immune response does not increase the ability of C. muris to establish a productive infection and produce oocysts.     

镉对海湾扇贝的急性毒性研究

利用水生生物毒性试验方法,分5个浓度进行镉对日照海域海湾扇贝的急性毒性实验,以期对日照海域海湾扇贝养殖提供理论依据。利用概率单位和浓度对数作线性回归,得出镉对海湾扇贝(Argopectenirradiams)在24、48、96h的半致死量LC50,其值分别为5.85、4.52和3.45mg/L。并计算出镉对海湾扇贝的安全质量浓度为0.0345mg/L。实验证明,Cd对海湾扇贝是剧毒性的毒物,海湾扇贝发育越往后期,它对Cd的耐受性就越大。     

几种常用消毒剂对细鳞鱼鱼种急性毒性试验

试验结果表明:消毒剂对细鳞鱼鱼种的毒性依次为硫酸铜>食盐>福尔马林。硫酸铜对细鳞鱼鱼种24h的LC_(50)为1.07 mg/L,食盐24h和48h的LC_(50)为13.06 mg/L、11.64 mg/L,福尔马林24h和48h的LC_(50)为20.71mg/L、17.13mg/L。     

聚维酮碘对海湾扇贝等贝类幼虫的毒性试验研究

测定了聚维酮碘(PVP—I)对虾夷扇贝、海湾扇贝、牡蛎的壳预期幼虫以及牡蛎的眼点期幼虫的24h半致死浓度分别为：32．5mg／L，31．7mg／L，44．4mg／L；安全浓度分别为：3．25mg／L，3．17mg／L，4．48mg／L，4．44mg／L。     

猪轮状病毒四川株的分离鉴定及增殖规律

为了解猪轮状病毒（PoRV）在MARC-145细胞系上的培养特性及增殖规律,本试验利用MARC-145细胞,从四川仔猪腹泻样品中分离到1株PoRV,并通过PCR检测、病毒理化实验与微量中和实验证实,命名为SC-R株。用含不同浓度胰酶营养液培养SC-R株48h后,分别收集病毒液进行定量分析;同时,以SC-R分离株感染MARC-145细胞,在感染后不同时间分别收集感染病毒液,利用PoRV荧光定量检测方法对不同样品中病毒RNA进行定量分析,绘制PoRV生长曲线。结果表明,用含3％胰酶营养液培养的细胞液中PoRV的RNA含量明显高于其他组;-步生长曲线显示细胞外病毒RNA含量呈“s型”曲线增长,感染后0～8h为潜伏期,病毒RNA含量维持在较低水平;8～36h为突破期,病毒RNA含量呈对数增长;感染48h增长速度减缓,维持在较高水平,逐步进入稳定期。胰酶可增加PoRV对细胞的感染性,3％是本试验最为适用的胰酶浓度;PoRV感染MARC-145后在细胞内增殖并逐步释到细胞外。     

昆虫病原线虫JLSY 003的鉴定及其生物学特性测定

经28S rDNA和ITS序列分析,从吉林省松原市土样中分离到的昆虫病原线虫JLSY 003为Oscheius myriophila品系。本研究以大蜡螟末龄幼虫为寄主,测定该线虫的生物学特性。结果表明,JLSY 003浓度为80 IJs/larva时具有较高的侵染力,致死中时间LT₅₀为15.409 h,侵染24、48 h时,致死中浓度LC₅₀分别为46.067、25.297 IJs/larva。JLSY 003高温耐受性强且繁殖力高,36 ℃、8 h时线虫死亡率为19.27%,产量为1.873×10⁵ IJs/larva,4.695×10⁵ IJs/g。结果表明该线虫具有较高的致病力、耐热性和繁殖力。     

基于卷积神经网络的农作物叶片病害诊断

农作物病害诊断对于及时发现并采取防控措施具有重要意义。本研究针对苹果、玉米、番茄、葡萄等典型农作物的常见叶片病害问题,使用了两种目前使用最广泛的卷积神经网络——VGG16及Resnet50,对典型农作物叶片病害进行识别。使用AI Challenger比赛的农作物叶片病害数据集图像,并对这些图像进行预处理,构建了47285张图片的数据集。分析两种卷积神经网络的性能,实验结果表明:VGG16及Resnet50分别达到了82.57%和86.34%的准确率,且Resnet50收敛速度更快,更适合农作物叶片病害的诊断识别。