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151.
W. M. Snyder 《Journal of the American Water Resources Association》1980,16(1):22-30
ABSTRACT: Sliding polynomials differ from other piecewise interpolation and smoothing methods in their functional continuity at the nodes. This functional continuity was used to establish optional spacing of nodes and optional boundary controls in data smoothing while still maintaining mathematically continuous rates or gradients. Cyclic as well as noncyclic data can be smoothed. Variance of the individual nodal values. derived through least-squares optimization, can be calculated using the rigorously determined weighting coefficients between data points and nodes. Such nodal variances are estimates of localized uncertainty in the data which complement the localization of smoothing through use of piecewise functions. Choice of controls in smoothing and calculation of variance have been incorporated in a computer program for user convenience. 相似文献
152.
ABSTRACT The efficiency of an inverted internal hydraulic jump as a mixing and dispersion mechanism in an aquatic environment was examined. The flow considered was a two-dimensional buoyant flow from a shallow channel over a sloping bottom into a deep reservoir. It could be seen that a rapidly varied flow associated with violent turbulent mixing occurred near the point of discharge if specific discharge conditions and downstream controls were met. Downstream from the mixing zone the flow was stably stratified. The main object of the study was to find the conditions under which a turbulent mixing zone occurred and the rate of turbulent entrainment. Energy loss and length of the mixing zone were also investigated. The independent variables were the outlet densimetric Froude number, the density differential between outfall water and receiving water, the relative depths of the upper and lower layers in the stratified flow portion, the total depth, and the slope of the transition. Theoretical calculations had to be confined to a step increase in depth, but experiments in a laboratory flume showed that results obtained with slopes of 23° and 90° were quite similar. Both theory and experiments showed, for example, that dilution (entrainment rates) up to 2:1 (2 parts heated water to one part cold water) can be achieved at very little energy expense and with downstream depths approximately 8 times the outlet depth. Theoretically, any amount of dilution can be obtained, but large depths may be required. Experimental results also indicate that the length of the mixing zone was frequently ten times the value of the outlet densimetric Froude number. 相似文献
153.
水泥土搅拌桩复合地基静载试验检测法的安全度分析 总被引:2,自引:1,他引:1
在检测水泥土搅拌桩复合地基的承载力能否达到设计要求时 ,最常用的方法是单桩静载试验法和复合地基静载试验法。工程实践中发现 ,采用这两种静载试验方法得到的检测结果存在较大差异。笔者根据水泥土搅拌桩的基本特性 ,结合工程实例 ,对这两种静载试验检测结果存在的差异及其安全度进行比较分析 ,得出单桩静载试验法结果的安全度高于复合地基试验法结果的结论 ,因此 ,提出了一些合理化建议 相似文献
154.
Main R. Hutcheson 《Journal of the American Water Resources Association》1998,34(5):1025-1033
ABSTRACT: Acute criteria are assigned to the fish and wildlife propagation beneficial use in Oklahoma's water quality standards. Dye studies are analyzed to show that these criteria can be implemented through acute regulatory mixing zones. Acute regulatory mixing zones may be defined as areas in receiving streams where acute numerical criteria may be exceeded without causing acute toxicity. Acute regulatory mixing zones are used to obtain acute waste load allocations. If effluent loading does not exceed acute waste load allocation, acute criteria exceedance is confined to the acute regulatory mixing zone and there is no acute toxicity in the receiving stream. Waste load allocations for acute and chronic criteria are compared to determine which is appropriate to develop permit limits for the dye studies. 相似文献
155.
A Multi-Channel Continuous Water Toxicity Monitoring System: Its Evaluation and Application to Water Discharged from a Power Plant 总被引:2,自引:0,他引:2
A multi-channel continuous water toxicity monitoring system was, after confirming the systems' performance, implemented to
samples of water discharged from power plants to detect and classify their toxicity using several recombinant bioluminescent
bacteria. Each channel of the system is composed of a series of two mini-bioreactors to enable a continuous operation, i.e.,
without system interruption due to highly toxic samples. A different recombinant bacterial strain was present in each channel:
DPD2540 (fabA::lux CDABE), DPD2794 (recA::luxCDABE), and TV1061 (grpE::luxCDABE), which are induced by cell membrane-, DNA-, and protein-damaging agents, respectively. GC2 (lac::luxCDABE) is a constitutive strain, whose bioluminescence is reduced by an increase in cellular toxicity. Phenol and mitomycin C (MMC)
were used for evaluating the system's performance to detect toxic chemicals. These samples were injected into the second mini-bioreactor
according to a step or bell-curve manner. The field samples used in this study were obtained from the water discharged from
two different power plants in Korea – from a nuclear power plant and a thermo-electronic power plant, and were injected into
the second mini-bioreactor to initiate the toxicity test. Each channel showed specific bioluminescent (BL) response profiles
due to the toxic compounds present in the water samples. Comparing the BL signals between the standard toxic chemical samples
and discharged water samples, the equivalent toxicity of the field water could be estimated. Finally, it was proved that this
novel continuous toxicity monitoring system can be used as an alternative tool for the quick monitoring and control of water
quality, as well as aid in the setting up of a new monitoring strategy to protect the source of tap water and in the prevention
of polluted water discharge. 相似文献
156.
157.
Tedesco M Bohlen WF Howard-Strobel MM Cohen DR Tebeau PA 《Environmental monitoring and assessment》2003,81(1-3):35-42
A network of five water quality monitoring stations has been established in Long Island Sound, measuring temperature, salinity, and dissolved oxygen since 1999. The stations are located in areas of extreme water quality degradation (western Long Island Sound) as well as in pristine areas (eastern Long Island Sound). The data from these stations are collected every 15 minutes and posted to the project web site in real time as provisional data. After subsequent quality assurance procedures, the data are archived to the project File Transfer Protocol (FSP) site for downloading by the user community. The network of stations is in part supported logistically by a number of partners, including state and local agencies, schools, and non-governmental organizations. Data from the monitoring programs of some of these partners are also published to the project website providing a more comprehensive and complete picture of the status of the Sound than can be provided independently. This repository of information is used by marine educators, resource managers, scientists, and the general public, each with a different end purpose. We use the data from two of the stations to show that these high frequency time series measurements can be used to complement and enhance other monitoring programs within the Sound, documenting in greater detail the occurrence and duration of hypoxic events. 相似文献
158.
连续流动分析在水质监测中的应用 总被引:6,自引:0,他引:6
连续流动分析技术具有分析速度快、准确度和精密度高、操作简单、通用性强、样品和试剂消耗量少等一系列优点。灵活运用连续流动分析技术可对大多数水性样品如水和废水、土壤(或固体废弃物)提取液、饮料等进行分析。本文中着重介绍了氨氮、硝酸盐氮/亚硝酸盐氮、挥发酚以及总氰化物等几个连续流动分析在水质监测中的应用实例。 相似文献
159.
2003年陕西持续性暴雨成因分析 总被引:13,自引:8,他引:13
对2003年发生在陕西的持续性暴雨分析认为: 乌山阻高与副热带高压的配置及稳定少动为这次持续性暴雨提供了有利的背景条件.贝湖低压底部分裂出小槽引导的冷空气与副高西北侧暖湿气流在高原东侧一带反复交绥是暴雨的主要成因.高低空急流耦合使高层辐散区迭加在低层辐合区的上方而产生强烈的上升运动,为深对流的发展提供了条件,促进了暴雨时中尺度系统的生成和维持. 相似文献
160.