共查询到20条相似文献，搜索用时 703 毫秒
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Laser beams can be used as long-range spectroscopic probes of the chemical composition and physical state of the atmosphere. The spectroscopic, optical, and laser requirements for atmospheric laser remote sensing are reviewed, and the sensitivity and limitations of the technique are described. A sampling of recent measurements includes the detection of urban air pollution and toxic chemicals in the atmosphere, the measurement of global circulation of volcanic ash in the upper atmosphere, and the observation of wind shear near airports. 相似文献
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准确快速的土壤重金属检测方法能为土壤重金属污染防治提供基础条件。直接固体进样技术因具有能简化样品前处理、缩短分析时间、减少有害化学试剂使用等特点,已被广泛用于农业土壤环境样品中各类金属元素含量的测定。鉴于此,本文首先概述了电热蒸发、激光烧蚀、等离子体进样、中子活化技术等典型土壤固体样品导入技术。其次,根据检测器的不同对固体进样技术进行了分类,并对其工作原理、国内外最新研究进展及标准现状进行了总结。本文进一步从样品的称样量及目数选择、校准方法、基体干扰和消除技术方面对土壤直接固体进样技术存在的问题进行了概述。最后,从土壤固体进样技术的自动化程度、精度提高、成本节约等方面对其未来发展方向进行了展望。 相似文献
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Preliminary experiments indicate that tunable Pb(1-x)Sn(x)Te diode lasers will be useful in the identification and sensitive detection of most of the atmospheric pollutant gases. For point-sampling applications, concentrations in the parts-per-billion range should be measurable with very high specificity. For long-range atmospheric transmission techniques, the improved resolution capability and tunability of these diode lasers make them attractive replacements for spectrometers and fixed-frequency laser sources where operation at cryogenic temperatures is not a serious impediment. By using these lasers as tunable local oscillators in the infrared heterodyne configuration, remote passive detection of gases present in smokestack effluent appears possible. Finally, pulsed operation at temperatures available with simple cryogenic coolers permits immediate application to the fast detection of gases present in automobile exhaust and in chemical processing plants. 相似文献
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The separation of atmospheric constituents by gravity has been proposed theoretically for almost two centuries. However, turbulent mixing has prevented the detection of this phenomenon in the lower atmosphere. By using precise measurements of the Ar/N2 ratio of air samples taken under strong nocturnal inversions, we have detected such separation in near-surface layers. The effect is shown to be consistent with combined influence of thermal and gravimetric separation, with the thermal contribution being more important. 相似文献
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我国农业面源污染情况复杂,提高对污染物的监测手段和检测能力对污染防控至关重要。污染物的实验室检测是污染监测的重要一环,能科学的反应农业面源污染的总量和来源,从而调整监测和防治方案。本文从农业面源污染的特点出发,梳理了农业面源污染的监测情况及污染物指标,详细归纳了pH、总氮（TN）、可溶氮、氨态氮（NH4+-N）、硝态氮（NO3--N）、总磷（TP）、可溶磷、含水率、有机质、全钾、有效磷、有效钾、化学需氧量（COD）、重金属、农药残留、多环芳烃（苯并[a]芘）等污染物的实验室检测方法和注意事项,为实验室开展农业面源污染物检测提供理论参考。 相似文献
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Dyer P 《Science (New York, N.Y.)》1992,256(5058):820-822
Although measurement of the solar neutrino flux via the (7)Li(v(e),e(-))(7)Be reaction was proposed many years ago, no experiment has been implemented since it has been difficult to identify a sensitive (7)Be detection technique. Here it is proposed that the (7)Be atom be incorporated into a volatile molecule, placed in a buffer-gas-filled cell, and then extracted by photodissociation; after excitation by a tunable laser, bursts of photons would be detected. The absorption spectrum of the molecular candidate diethylberyllium has been measured between 186 and 270 nanometers in a spectrophotometer to determine the required photodissociation laser wavelength and intensity. 相似文献
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阐述了在胶南自然条件下生产无公害绿茶的主要技术，从环境选择、地力改善、肥料施用、病虫害管理等方面进行了详细的论述，为江北无公害绿茶生产提供了良好的借鉴。 相似文献
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我国水环境中持久性有机污染物污染的现状及研究进展 总被引：2，自引：0，他引：2
持久性有机污染物(POPs)因其对环境和人类健康的严重危害而成为倍受关注的全球性环境问题.对持久性有机污染物的特点、种类及近年来我国水环境中POPS的污染现状、检测技术和消除处理技术的研究进展进行了综述. 相似文献
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采用同时蒸馏萃取法(SDE)分别提取2月份采摘的峨眉含笑、南亚含笑、毛果含笑叶片的挥发油,运用毛细管气相色谱-质谱联用法结合计算机检索分析其化学组成。结果表明,峨眉含笑、南亚含笑、毛果含笑叶片经SDE提取所得挥发油共分离鉴定出42种挥发性化合物,其中峨眉含笑28种、毛果含笑20种、南亚含笑29种,分别占挥发性物质总含量的83.54%、88.15%和92.58%。3种挥发油化学组成各有异同,3种植物共有的化合物有α-愈创木烯、匙叶桉油醇、c-木罗烯、绿叶烯、马兜铃烯、α-胡椒烯、1(10),4-杜松二烯、反式-去氢白菖烯、tau-杜松醇、tau-木罗醇和α-杜松醇等11种。这3种植物挥发油中富含大量在香料和医药行业有重要用途的高生物活性化合物。从组分多度相似百分率的分析结果看,峨眉含笑与毛果含笑的组分多度相似百分率为41.33%,处于极近似水平,挥发性化学成分的组成关系较密切,而南亚含笑与毛果含笑以及与峨眉含笑的组分多度相似百分率分别为30.19%和29.73%,处于较近似水平,组成关系相对较疏远。 相似文献
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Inelastic electron tunneling spectroscopy is a useful technique for the study of vibrational modes of molecules adsorbed on the surface of oxide layers in a metal-insulator-metal tunnel junction. The technique involves studying the effects of adsorbed molecules on the tunneling spectrum of such junctions. The data give useful information about the structure, bonding, and orientation of adsorbed molecules. One of the major advantages of inelastic electron tunneling spectroscopy is its sensitivity. It is capable of detecting on the order of 10(10) molecules (a fraction of a monolayer) on a 1-square-millimeter junction. It has been successfully used in studies of catalysis, biology, trace impurity detection, and electronic excitations. Because of its high sensitivity, this technique shows great promise in the area of solid-state electronic chemical sensing. 相似文献
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Nitric oxide is detected by a new technique in which tunable infrared radiation from a spin-flip Raman laser is used to measure the absorption spectrumn of a gas sample by optoacoustic spectroscopy. This technique is sensitive enough to detect a concentration of 0.01 part per million of nitric oxide pollution in air samples. 相似文献
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为建立快速、准确的赤潮藻鉴定和定量检测方法,以红色裸甲藻(Gymnodinium sanguineum)作为研究对象,将快速检测手段一实时荧光定量PCR(RFQ-PCR)技术应用于赤潮藻的种类鉴定中.首先以红色裸甲藻18S rDNA序列为靶区域.设计出适合用于RFQ-PCR技术的红色裸甲藻引物和TaqMan探针,并通过引物PCR验证确定其种特异性;进而应用实时荧光定量PCR方法建立红色裸甲藻快速检测方法.与显微镜计数方法比较,两者所获结果无显著性差异,且该方法的检测限远低于红色裸甲藻爆发赤潮时的藻密度,因此该方法可有效地应用于红色裸甲藻的检测,从而为红色裸甲藻赤潮的预警预测奠定基础. 相似文献
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结合酶底物法检测粪大肠菌群的相关研究,运用酶底物在线监测系统对上海市某河段进行检测,用标准方法-多管发酵法进行同步检测,讨论在线酶底物法在地表水中检测粪大肠菌群的适用性。结果表明,2种方法的测定数据显著相关,没有统计学差异（P＞0.05）。相对于多管发酵法,在线酶底物法特异性强,检测时间短,自动进样,自动检测,二次污染少,可以实现地表水、饮用水等重要水源地的实时监测需求,对地表水的污染程度监控和卫生学质量评价具有重要作用。 相似文献
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由于工业、农业、废水处理、建筑和采矿等一系列人为活动造成土壤的污染程度日益严重,致使土壤不能用于粮食等作物生产.如何深入治理重金属污染土壤已成为当今研究的热点.由于传统的治理重金属污染技术非常昂贵,并存在二次污染的风险,促使研究者寻求新的治理技术.而植物修复技术以其价廉、清洁、不破坏环境、不会造成二次污染等特性逐步引起了学术界和政府部门的广泛重视.近年来,工业大麻以其优良的修复特性和利用价值已成为修复重金属污染土壤的候选植物之一.在此重点论述了重金属对工业大麻的影响及其在大麻不同部位的分布;工业大麻对重金属的吸收能力以及工业大麻对重金属污染土壤修复的优良特性,最后对工业大麻修复重金属污染土壤技术存在的不足等进行归纳总结,以便为工业大麻对重金属污染治理研究及耐重金属或超富集工业大麻品种的选育和栽培技术研究提供指导. 相似文献
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居住区受区外交通噪声污染影响分析及防治对策的研究——以天津“第六城”居住区为例 总被引：1，自引：0，他引：1
交通的发展使噪声污染加剧，改善和保障住宅声环境意义重大。本文通过天津“第六城”居民住宅区的设计实例，提出建筑设计和小区规划中减少交通噪声影响的有关措施：包括在居住区的规划中，对不敏感的建筑物和利用绿化隔离带形成小区周边的声屏障，加强住宅建筑设计中隔声构造处理等方面提出了具体的技术措施。对其他居住区开发建设具有借鉴意义。 相似文献