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141.
142.
遵照分类检索“以类索文,触类全貌,类目编排,严谨科学”的基本原则及本数据库独具专题综合性的特殊要求,以中国图管分类法为基础,优选有关1~4级类目、类号,显明简要的类目注释.并制定一套划分文献的规则,依类揭示本库所收录的节水农业文献信息,满足有关用户以类索文的需要。 相似文献
143.
基于芯样的沥青路面抗剪性能评价指标 总被引:1,自引:0,他引:1
以沥青路面的取芯芯样为研究对象,采用动载单轴贯入试验方法,通过有限元理论分析和对比试验确定了试验条件和参数,确定以一定作用次数下的贯入深度作为指标,能够较好地评价沥青路面的抗剪切性能. 相似文献
144.
文章从全区人工造林更新实绩核查的实际出发 ,论述了全区造林核查数据处理软件的研制方法和过程 ,并详细介绍了软件的功能及使用效果。该软件的研制和使用对全区造林核查管理工作具有十分重要的价值。 相似文献
145.
文章介绍了当前业界信息安全管理常用的ASSET、COBRA和Callio Secura 17799 3种软件的基本情况,然后从发行公司、运行平台、操作过程、功能等方面进行了比较,最后对这三种软件的使用对象提出了些建议。 相似文献
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Standard for Bamboo and its International Trend 总被引:1,自引:0,他引:1
WANG Zhaohui JIANG Zehui SUN QixiangResearch Institute of Wood Industry Chinese Academy of Forestry Beijing P.R. China 《中国林业科技(英文版)》2004,3(2):55-65
1 INTRODUCTIONNational forestry ecological engineering, as afundamental affair for environmental protectioncontains combating desertification, soil and waterconservation. Two measures might be taken to preventsoil and water losses. One measure is to enlarge theforest area and to stop cutting or to decrease cuttingforest so as to make forest coverage keep rising at astable speed, forest resources should be examined byremote sensing technology. The other is to control thecirculation of wood… 相似文献
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149.
We evaluate a source of error observed in standard ichthyoplankton bongo tows in which volumes of water filtered did not result in increased catches of red-fish. Our analyses demonstrate that, under conditions where redfish larvae are distributed in surface waters in a two-layered system, current differentials between surface and subsurface layers resulted in biased, standardized estimates of larval abundances as a result of filtering varying amounts of subsurface waters. Analysis of standard survey results on Flemish Cap demonstrated that this source of bias was limited to the May-June period, after waters became stratified and before redfish passed from the larvae to pelagic juvenile stage. Correcting for this source of sampling bias wIII result in more accurate absolute estimates of ichthyoplankton abundance, and we estimate that variation (CV) for replicate samples may be reduced by 10%. 相似文献
150.
Asma Ali Abahussain Abdelhadi Abdelwahab Mohamed Ahmed Ali Salih Ahmad Al Safe Nader Abdul Hamed Mosa Yahya Othman 《农业科学与技术》2014,(2):112-122
Monitoring and assessment of agricultural land degradation is of vital importance for better land and water management planning and reclamation. It requires setting baseline information and basic analysis at specific time and space. About 33 geo-referenced soil sampling spots were selected in two agricultural production locations in the Kingdom of Bahrain to assess the status and preliminary causes of land degradation. Soil samples were taken from 13 sites in Diraz location while 19 samples were taken from Budayyi location. The samples were taken to 90 cm depth at 30 cm intervals. Standard procedures were followed to determine soil physiochemical properties. In addition, field observations on farm condition, distance from the sea, method of irrigation and irrigation water source were taken. Some of the soil samples were deliberately taken from outside the irrigated basins among trees compared with samples taken from inside the actively growing area for comparison. The results indicated that the salinity level was significantly (P 〈 0.001) higher at the 0-30 cm soil depth compared with 30-60 cm or 60-90 cm depths in both locations. The distance from the sea did not show clear correlation with surface soil salinity in Budayyi area compared with Diraz. Both locations showed significantly higher salinity levels on samples taken outside the actively growing areas compared with those taken from within. The effect is more prominent at the 0-30 cm depth. The observed variability on salinity levels may be attributed to farm management practices and deteriorating quality of ground water. Thus, agricultural land degradation in Bahrain cannot be attributed to ground water deterioration alone. The use of tertiary treated sewage water (TSE) may ease the pressure on ground water, but the pH of the TSE should be carefully monitored and managed with proper studies on leaching requirements to avoid further salinity complications. 相似文献