载畜率对荒漠草原植物群落影响的研究

对不同载畜率下短花针茅荒漠草原植物群落特征进行比较,结果表明:不同植物种群的盖度对载畜率的响应不同,无芒隐子草盖度在轻度放牧区最大,栉叶蒿盖度在7月份、8月份分别以中度放牧区和轻度放牧区最大;短花针茅、冷蒿、阿氏旋花、细叶葱、木地肤随载畜率增大高度下降明显,猪毛菜高度在四个载畜率下差异均不显著;随着载畜率的增大,植物群落生物量呈下降趋势,且重度放牧与不放牧、轻度放牧有显著差异;随着载畜率的增大,建群种、优势种地位改变不明显,但一年生的猪毛菜重要值增大,在重度放牧区达到最大并占据优势地位;Shannon-wiener指数、Simpson指数、Pielou均匀度指数均以轻度放牧区最大,Shannon-wiener指数、Simpson指数均为轻度放牧>中度放牧>重度放牧>不放牧,且不放牧与轻度放牧差异显著。     

Cow-level evaluation of a kinetics ELISA with multiple cutoff values to detect fecal shedding of Mycobacterium avium subspecies paratuberculosis in New York State dairy cows

In control programs for Mycobacterium avium subsp. paratuberculosis (Map), the infection status of the cows in a herd is often obtained by testing (a sample of) the herd with an ELISA that may lack some sensitivity and specificity but that is fast and inexpensive. In New York State (NYS), an unabsorbed kinetics ELISA (KELA) has been used extensively for Map control. The objective of this study was to determine the relative sensitivity and specificity of the KELA for detection of fecal shedding of Map for the NYS dairy cow population, taking into account possible confounders such as different antigen batches and Map prevalence in a herd.

The data for the study consisted of all serum samples from NYS dairy cows with concurrent fecal culture results submitted to the NY Animal Health Diagnostic Laboratory (NYAHDL) between 1991 and 1996 (n = 10,562). The data represented cows with different levels of fecal shedding from herds with different within-herd Map prevalence, including herds that were whole herd fecal culture negative on repeated testing.

The cutoff values were based on the predictive value for fecal shedding obtained with a multiple logistic regression model that included variables for the three antigen batches and the Map prevalence in the herd. The KELA could not distinguish between non-shedders and low shedders (≤30 total colony forming units (TCFU)) and thus the predictive value of the KELA to detect moderate to heavy fecal shedders (>30 TCFU) was modeled. The three cutoff values of 65, 135 and 170 were based on low (<0.2), moderate (<0.80) and high (>0.95) probabilities for moderate to heavy fecal shedding. The sensitivity and specificity values relative to culture were 67% and 95.2%, 31% and 99.7%, and 11% and 99.9% for the three cutoff values, respectively. Cutoff values for the KELA decreased for herds with increasing within-herd Map prevalence. For the best positive predictive value of a KELA for moderate to heavy fecal shedding, the cutoff values should be determined based on the apparent within-herd prevalence in a herd.     

广西野生饲用植物资源考察

通过对广西野生饲用植物资源历时5年的考察,基本上摸清了野生饲用植物的种类分布及组成,了解了野生饲用植物的特点和营养价值,并提出了进一步开发利用本地饲草用植物资源的建议。对指导当前大力发展种草养畜,合理利用本地资源将具有现实意义。     

不同阶段矮小型褐壳蛋鸡血液生理生化指标测定

试验测定20、40、60周龄矮小型褐壳蛋鸡血液生理指标、血清生化指标,每一周龄公、母鸡各9只,样本量为54只。将数据进行t检验及多重比较分析,结果表明,在此3个时间点上,指标RBC、HGB、MPV、PDW、LYMF%、TP和CHO呈现上升趋势,指标HCT、MCV、RDW%、WBC、LYMF值是先下降后上升,而MCH、MCHC、PCT、PLT、MID、MID%、GRAN、GRAN%、AST、ALB、TG、GLU和ALT值是先上升后下降。同时,不同周龄鸡之间在血液生理生化指标上表现出不同项目差异显著(P0.05)。20、40及60周龄矮小型褐壳蛋鸡雌、雄间均存在显著差异(P0.05)的血液生理生化指标有RBC、HCT、HGB、WBC、LYMF和AST,这表明矮小型褐壳蛋鸡的生理和生化指标随周龄不同,在雌、雄之间的差异随之发生变化。     

Economic evaluation of financial and non-financial costs and benefits in agroforestry development and the value of sustainability

Financial appraisal of agroforestry is not different in kind from appraisals applied to pure forestry. Existing techniques for valuing non-market effects may also be applied. Effects on hydrological and carbon fluxes might be less favourable than those of pure forests. In the confusing field of biodiversity valuation too, only limited and specific claims can be made for agroforestry. Amenity valuation techniques developed for trees and woodlands encounter additional problems of interpretation in an agroforestry context. Agroforestry may offer a quantifiable value in short-term sustainability, and might meet recent economic definitions of long-term sustainable development, without encountering the full dangers to future generations embodied in conversion of natural to human capital.     

玉米不同抗旱杂交组合的研究

通过田间抗旱鉴定试验,采用模糊函数法对不同玉米杂交组合的抗旱性进行综合评价,并进一步通过品比试验研究各组合的丰产性,结果表明：411×18599、苏11×449、79-1E×S7913、交51×411、5311×449、5311×S1-1、18599×1125、交51×5311、411×S1-1、S1-1×449和79-1E×449等组合的抗旱性和丰产性表现较好,抗旱性在Ⅲ级中抗以上,产量达80907.70 kg/hm2,是抗旱高产杂交组合,可以在生产上加以应用。     

青海微孔草经济价值及开发利用前景

微孔草是一种野生珍稀油料植物。本文通过对青海微孔草生物学特性及分布、生态学特性及经济价值的分析,指出微孔草富含r-亚麻酸,具有较高的营养价值和保健价值,并对微孔草的开发利用前景进行了分析。     

当前我国青少年主流价值观的建构

当前我国青少年主流价值观的建构应通过课堂教育、典型感化、参与社会实践活动等途径，教育和引导他们树立社会主义的主流价值观。     

山东省濒危药用鸟类分布与保护

山东省共有濒危药用鸟类25种;科学研究及临床证实,药用鸟类具有较高的药用价值;阐述了山东省药用鸟类资源分布和利用现状,并提出一些保护和合理开发的建议。     

森林社会效益价值评价研究综述

对森林社会效益的认识可以追溯到18世纪的德国,主要是由于对森林美学的研究而引起的,其评价研究始于20世纪40年代.对森林社会效益,目前国内外还没有形成一个明确的、权威的定义,多数定义主要是对森林社会效益内容的描述、列举,还缺乏一个明确的、本质性的界定,还需要从经济学、生态学、环境经济学、林学和社会学等角度进行探索、研究.对评价内容也没有形成统一的认识,也处在认识、研究之中.比较认同的评价内容是森林提供的就业机会、森林游憩和森林的科学、文化、历史价值.森林社会效益的价值评价方法的研究,更是一个复杂的系统工程,目前,对森林提供的就业机会主要采用投入产出法、指数法评价;对森林游憩价值主要采用旅行费用法等评价;对森林科学、文化、历史价值主要采用指标评价法、条件价值法和综合模型评价法等评价.