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991.
本文利用减压微色谱柱,研究了CL-7402树脂分离富集钯的性能。  相似文献   
992.
为解决田间调查时因信息沟通手段与渠道的制约而产生的苗情灾情报送迟滞这一瓶颈问题,基于Android手机平台,构建了一种作物苗情灾情快速上报系统。系统由服务器端和客户端两部分组成。服务器端主要负责苗情灾情数据的存储与下载,研究中采用HTTP文件服务器,可通过设置IP、端口及用户名、密码和共享路径等实现远程文件的上传与下载;客户端主要实现苗情灾情的采集与上传,研究中依托手机自带拍照、GPS定位、数据传输等功能,基于Android编程技术对系统的功能和界面进行了设计。系统主要功能包括苗情灾情固定与非固定地块的实时采集、汇总与远程服务端(云平台)传输。由于系统基于Android设备开发,有效降低了常规硬件部件的费用,最大限度地降低使用成本。经过2年多的初步测试使用表明,系统具有较好的稳定性及时效性,苗情灾情速报功能可满足市级管理人员的基本需求,可实现大面积苗情灾情数据的快速统计、实时上报,从而为获取实时农情数据和开展灾后救援工作提供可靠支撑。  相似文献   
993.
Simultaneous determinations of U–Pb dating and Hf isotopes on single zircon grains by excimer laser-ablation quadrupole and multiple-collector ICP-MS and petrologic and ore geochemical studies have been applied to the ore-bearing porphyry of the Jinduicheng porphyritic molybdenum deposit in East Qinling. Lithogeochemical data show that the porphyry is characteristic of high K2O, K-feldspar porphyritic calc-alkaline granitoids with 176Hf/177Hf=0.282020–0.282436 and εHf(t)=?23.7 to ?8.9, which indicates its mixed origin involving a crustal and a mantle component. The weighted average U–Pb age from single zircon grains of the porphyry is 141.5±1.5 Ma. This age coincides with the oldest molybdenite Re-Os model age as dated by others, suggesting that the period of mineralization was almost simultaneous with the porphyry emplacement, or slightly later. The porphyry intrusion and the molybdenum mineralization occurred during the transition from compression to extension in the Jurassic – Cretaceous periods. The corresponding tectonic setting was the intracontinental orogenic and extension stage after collision and orogenesis between the Southern China plate and the Northern China plate. The Jinduicheng porphyry and the deposit's geochemical data indicate that the ore-forming material originated from a mixing of lower crust and upper mantle. When the molybdenum-enriched magma intruded into the upper crust along zones of structural weakness, ore-forming fluid generated by magma crystallization of the porphyry interacted with wall rock or mingled with meteoric water to form the deposit.  相似文献   
994.
对北京市凤河营等地震台智能电源管理下的蓄电池放电数据进行处理和分析,发现蓄电池电压"平缓—快速—平缓"的下降过程可以表征蓄电池老化程度的现象,获得蓄电池小电流放电条件下每次放电过程的估算容量数据,实证蓄电池放电容量与温度之间存在正相关关系,且发现同批次蓄电池可能存在较大程度的容量差异。及时的数据处理分析,对于准确把握蓄电池工作状态、保障台站供电安全、合理安排蓄电池更新事务,可以起到积极的作用。  相似文献   
995.
以陇中黄土丘陵区魏店镇为研究对象,基于村庄详细调查数据库,在农村居民点空间布局形态分析的基础上,构建乡村“基础生活圈”和布局适宜性评价指标体系,识别农村居民点空间重构类型并提出应对策略。结果表明:① 魏店镇农村居民点受自然禀赋和交通因素的影响,呈现出“集中为主、分散为辅、散中有聚”的空间布局特征,且景观分异明显;② 10和20 min生活圈内覆盖的居民点面积和数量差异较大,相对集聚状态下的居民点更容易获得公共服务设施;③ 农村居民点布局适宜程度较好,以中、高度适宜为主,二者斑块数量达到1742个,占到所有居民点总数的85.18%;④ 运用空间错位分析的二维组合矩阵将农村居民点“基础生活圈”和布局适宜性评价相叠加,重构为集聚提升型、引导发展型和搬迁扶持型。  相似文献   
996.
十八世纪我国长江下游等地区的气候   总被引:8,自引:1,他引:8  
关于1500-1900年小冰期气候问题是历史时期气候变化研究中的一个重要课题.本文根据我国晴雨录、古代天气日记、诗文等历史文献资料来讨论小冰期中一个相对温暖时期(十八世纪)的气候.研究表明,这个时期冬季(12-2月)平均气温比现在低1.0℃(杭州、苏州)到1.5℃(南京).但其间还有10年以上时间尺度的起伏波动,在温暖时段,冬季平均气温仍比现在低0.5-1.6℃,在寒冷时段,冬季平均气温比现在低2.1-2.4℃.但十八世纪大部分时期春季反比现在暖些.对湿润状况分析表明,十八世纪长江中下游地区比现代潮湿,反映了当时大气环流与今有较大差别.杭州古风向记录(1723-1769年)分析表明,当时盛行风向与现在不同:冬季西北风频率比现在多,春秋盛行东北风时间比现在长,频率比现在多.  相似文献   
997.
宁乡式铁矿在湘西北主要分布在三个层位,存在两类矿石结构,这两类矿石结构的铁矿是由不同的成矿方式形成,因而矿石质量也是不同的,具体表现在两类矿石中P、SiO2的含量存在明显差异。通过分析对比,Fe0、Fe22层砾状、豆状类赤铁矿的质量优于鲕状赤铁矿,其中位于二户溪至西界地区的FeO层砾状、豆状赤铁矿矿石质量全区最佳,应为该区的赤铁矿下一步工作的主要方向。  相似文献   
998.
To gain new insights into the variability of particulate organic carbon (POC) fluxes and to better understand the factors controlling the POC/234Th ratios in suspended and sinking particulate matter, we investigated the relationships between POC/234Th ratios and biochemical composition (uronic acids, URA; total carbohydrates, TCHO; acid polysaccharides, APS; and POC) of suspended and sinking matter from the Gulf of Mexico in 2005 and 2006. Our data show that URA/POC in sediment traps (STs), APS/POC in the suspended particles, and turnover times of particulate 234Th in the water column and those of bacteria in STs inside eddies usually increased with depth, whereas particulate POC/234Th (10–50 μm) and the sediment-trap parameters (POC flux, POC/234Th ratio, bacterial biomass, and bacterial production) decreased with depth. However, this trend was not the case for most biological parameters (e.g., phytoplankton and bacterial biomass) or for the other parameters at the edges of eddies or at coastal-upwelling sites.In general, the following relationships were observed: 1) 234Th/POC ratios in STs were correlated with APS flux, and these ratios in the 10–50 μm suspended particles also correlated with URA/POC ratios; 2) neither URA fluxes nor URA/POC ratios were significantly related to bacterial biomass; 3) the sum of two uronic acids (G2, glucuronic, and galacturonic acid, which composed most of the URA pool) was positively related to bacterial biomass; and 4) the POC/234Th ratios in intermediate-sized particles (10–50 μm) were close to those in sinking particles but much lower than those in > 50 μm particles. The results indicate that acid polysaccharides, though a minor fraction (~ 1%) of the organic carbon, act more likely as proxy compound classes that might contain the more refractory 234Th-binding biopolymer, rather than acting as the original 234Th “scavenger” compound. Moreover, these acid polysaccharides, which might first be produced by phytoplankton and then modified by bacteria, also influence the on-and-off “piggy-back” processes of organic matter and 234Th, thus causing additional variability of the POC/234Th in particles of different sizes.  相似文献   
999.
近百年四季西太平洋副热带高压的变化   总被引:3,自引:1,他引:3  
文中设计了一种根据网格点高度值拟合副热带高压强度、西界、北界 3种指数的方法。根据这个方法 ,利用重建的 1880~ 195 0年 5 0 0hPa月平均高度序列 ,计算了 195 1年之前 70a的副热带高压指数 ,与 195 1~ 1999年的实测指数合成一个 12 0a的序列 ,研究了西太平洋副热带高压的年际与年代际变率。  相似文献   
1000.
It is critical to study how different forest management practices affect forest carbon sequestration under global climate change regime. Previous researches focused on the stand-level forest carbon sequestration with rare investigation of forest carbon stocks influ- enced by forest management practices and climate change at regional scale. In this study, a general integrative approach was used to simulate spatial and temporal variations of woody biomass and harvested biomass of forest in China during the 21st century under dif- ferent scenarios of climate and CO2 concentration changes and management tasks by coupling Integrated Terrestrial Ecosystem Carbon budget (InTEC) model with Global Forest Model (G4M). The results showed that forest management practices have more predominant effects on forest stem stocking biomass than climate and CO2 concentration change. Meanwhile, the concurrent future changes in cli- mate and CO2 concentration will enhance the amounts of stem stocking biomass in forests of China by 12%-23% during 2001-2100 relative to that with climate change only. The task for maximizing stem stocking biomass will dramatically enhance the stem stocking biomass from 2001~100, while the task for maximum average increment will result in an increment of stem stocking biomass before 2050 then decline. The difference of woody biomass responding to forest management tasks was owing to the current age structure of forests in China. Meanwhile, the sensitivity of long-term woody biomass to management practices for different forest types (coniferous forest, mixed forest and deciduous forest) under changing climate and CO2 concentration was also analyzed. In addition, longer rotation length under future climate change and rising CO2 concentration scenario will dramatically increase the woody biomass of China during 2001~100. Therefore, our estimation indicated that taking the role of forest management in the carbon cycle into the consideration at regional or national level is very important to project the forest carbon sequestration under future climate change and rising atmospheric CO2 concentration.  相似文献   
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