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151.
152.
分析与评价一个地区森林的间接经济价值是当前生态经济学研究的重要课题。根据森林生态系统服务价值的计算方法,估算出恩施州森林生态系统间接经济价值为9.948 1×108元/年,其大小顺序依次为:保护生物多样性>固CO2释O2>育土保肥>水土保持>净化空气。评估森林间接经济价值旨在强调森林的生态功能,促进以可持续发展战略为重点的科学发展观,为核算绿色GDP奠定基础。 相似文献
153.
《Communications in Soil Science and Plant Analysis》2012,43(13):1624-1639
ABSTRACTKnowledge of the initial soil fertility status is very crucial to make the soil test-based fertilizer recommendations and therefore it is necessary to develop alternative techniques to predict the post-harvest soil test values than analyzing the soils after every crop. The study was done to develop multiple linear regression (MLR) models to predict soil available nitrogen, phosphorus and sulfur in the hybrid rice-wheat cropping sequence. The post-harvest soil test values were considered as the dependent variable and initial soil nutrients applied nutrient through fertilizer and farmyard manure and grain yield as independent variables. In general, the accuracy of prediction for the calibration and validation models using the single year and two-year data model was significant and had a coefficient of determination was ≥0.75. Although the performance of MLR model to predict post-harvest soil N, P and S after the individual crop was better than that after whole rice-wheat cropping sequence, predictions of the post-rice-wheat sequence of soil N, P and S also had acceptable levels of accuracy. Thus, the concept of the using the MLR-based models to predict the post-harvest soil test values could be used in hybrid rice-wheat cropping sequence to make the soil test-based fertilizer recommendations to the individual crops or whole cropping sequence. 相似文献
154.
《Communications in Soil Science and Plant Analysis》2012,43(6):607-618
Abstract Red pine (Pinus resinosa Ait.) seedlings were grown for 15 weeks over a range of nutrient regimes to calibrate a test procedure used for monitoring nutrient status of a common container growing medium. The test was based on a saturated aqueous extract of the growing medium, obtained by suction displacement. Seedling growth and nutrition exhibited typical responses of deficiency, sufficiency, luxury consumption and toxicity over the range of substrate fertility examined. Water extractable nutrients of the growing medium were related to yield and nutrient uptake of the seedlings. Ranges of nutrient levels associated with maximum dry matter production were selected as provisional values for optimum growth of containerized red pine seedlings. The following critical nutrient levels were considered optimum for red pine seedlings managed under similar cultural conditions: 15–65 ppm N (as NH4 +), 35–95 ppm P, 25–115 ppm K, 30–60 ppm Ca, 15–35 ppm Mg, and electrical conductivity of 1.0–2.2 dS/m. 相似文献
155.
Geffré A Concordet D Braun JP Trumel C 《Veterinary clinical pathology / American Society for Veterinary Clinical Pathology》2011,40(1):107-112
Abstract: International recommendations for determination of reference intervals have been recently updated, especially for small reference sample groups, and use of the robust method and Box–Cox transformation is now recommended. Unfortunately, these methods are not included in most software programs used for data analysis by clinical laboratories. We have created a set of macroinstructions, named Reference Value Advisor, for use in Microsoft Excel to calculate reference limits applying different methods. For any series of data, Reference Value Advisor calculates reference limits (with 90% confidence intervals [CI]) using a nonparametric method when n≥40 and by parametric and robust methods from native and Box–Cox transformed values; tests normality of distributions using the Anderson–Darling test and outliers using Tukey and Dixon–Reed tests; displays the distribution of values in dot plots and histograms and constructs Q–Q plots for visual inspection of normality; and provides minimal guidelines in the form of comments based on international recommendations. The critical steps in determination of reference intervals are correct selection of as many reference individuals as possible and analysis of specimens in controlled preanalytical and analytical conditions. Computing tools cannot compensate for flaws in selection and size of the reference sample group and handling and analysis of samples. However, if those steps are performed properly, Reference Value Advisor, available as freeware at http://www.biostat.envt.fr/spip/spip.php?article63 , permits rapid assessment and comparison of results calculated using different methods, including currently unavailable methods. This allows for selection of the most appropriate method, especially as the program provides the CI of limits. It should be useful in veterinary clinical pathology when only small reference sample groups are available. 相似文献
156.
Simone Bregaglio Marcello Donatelli Roberto ConfalonieriMarco Acutis Simone Orlandini 《Agricultural and Forest Meteorology》2011,151(9):1163-1172
Leaf wetness (LW) is one of the most important input variables of disease simulation models because of its fundamental role in the development of the infection process of many fungal pathogens. The low reliability of LW sensors and/or their rare use in standard weather stations has led to an increasing demand for reliable models that are able to estimate LW from other meteorological variables. When working on large databases in which data are interpolated in grids starting from weather stations, LW estimation is often penalized by the lack of hourly inputs (e.g., air relative humidity and air temperature), leading researchers to generate such variables from the daily values of the available weather data.Although it is possible to find several papers about models for the estimation of LW, the behavior and reliability of these models were never assessed by running them with inputs at different time resolutions aiming at large-area applications. Furthermore, only a limited number of papers have assessed the suitability of different LW models when used to provide inputs to simulate the development of the infection process of fungal pathogens. In this paper, six LW models were compared using data collected at 12 sites across the U.S. and Italy between 2002 and 2008 using an integrated, multi metric and fuzzy-based expert system developed ad hoc. The models were evaluated for their capability to estimate LW and for their impact on the simulation of the infection process for three pathogens through the use of a potential infection model. This study indicated that some empirical LW models performed better than physically based LW models. The classification and regression tree (CART) model performed better than the other models in most of the conditions tested. Finally, the estimate of LW using hourly inputs from daily data led to a decline of the LW models performances, which should still be considered acceptable. However, this estimate may require further work in data collection and model evaluation for applications at finer spatial resolutions aimed at decision support systems. 相似文献
157.
P. K. MATHUR 《华南农业大学学报》2005,26(Z1)
1The concept of connectednessThe term“connectedness”is commonlyused in animal breeding in relation to the geneticevaluations and across herd comparison of esti-mated breeding values.In this context,connect-edness is a measure or accuracy of across herd e-valuations.It can be described as a measure ofthe relationships between herds or contemporarygroups based on their effect on the accuracy ofcomparing the genetic values of animals fromoneherd or group to the other.In true statistical sense,a data set is con... 相似文献
158.
郭德兵 《信阳农业高等专科学校学报》2005,15(3):56-57
奥运离不开人文精神,人文精神推动了奥运的发展。以人为本、东西方文化交融、体育与教育相结合的奥运会,既是国际奥林匹克运动创立者的初衷,又是其和谐发展的指向。 相似文献
159.
新疆白绒山羊北疆型(不含野血)生理生化血液流变学常值研究 总被引:2,自引:0,他引:2
本研究系统测试了新疆乌苏地区北疆型(不含野血)白绒山羊公母共70只的生理生化血液流变学常值,并作了计算处理。结果表明:新疆白绒山羊北疆型(不含野血)的生理指标红细胞压积、血红蛋白较其它绒山羊高;生化指标血清总脂、血清胆固醇、钙值较其它绒山羊高;新疆白绒山羊北疆型(不含野血)的红细胞变形性较差;生产性能指标产绒量与血液生理生化血液流变学指标的相关性分析表明:HCT、RBC、血沉方程K值、P、A/G均可作为标记性状用于新疆白绒山羊北疆型(不含野血)的产绒量的间接选择,以HCT和P作为标记性状效果最佳。 相似文献
160.
ABSTRACT French bean (Phaseolus vulgaris L.) cv. ‘Anupama’ was grown in refined sand at variable levels of cobalt (Co), i.e., 0.0001 (control), 0.05, 0.10, 0.20, 0.40, and 0.50 mM, supplied as cobalt sulfate. The symptoms of excess Co (0.50 mM) appeared at day 35. In addition to growth depression, the young leaves developed chlorosis from the apex leading toward the base; the chlorosis intensified, changed to necrosis, and the infected leaves dried and withered. Under excess Co (> 0.0001 mM), the flowers produced were fewer in number, smaller, and many failed to mature, leading to lower seed yield. Excess Co (> 0.0001 mM) decreased the biomass, seed yield (number and weight), concentration of chlorophyll, Hill reaction activity, and activity of catalase, and deteriorated the quality of produce (sugars, starch, and protein nitrogen (N)), but it increased the concentration of phenols and activity of certain enzymes, i.e., peroxidase, ribonuclease, and acid phosphatase. The concentration of Co in various parts of French bean increased with an increase in Co supply and that of iron (Fe) decreased concomitantly. The values of threshold of toxicity and toxicity of Co were 26 and 72 μg g?1 in young leaves of French bean, respectively. 相似文献