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161.
Peter R. Waylen Matthew R. Zorn 《Journal of the American Water Resources Association》1998,34(1):149-157
ABSTRACT: A frequency analysis approach for the prediction of flow characteristics at ungaged locations is applied to a region of high annual precipitation and low topography in north and central Florida. Stationary time series of annual flows are fitted with the lognormal distribution and estimated parameters of the distribution are fitted by third order trend surfaces. These explain 65 and 74 percent of the observed variances in the mean and standard deviation, respectively. Predictions of parameters are then made for several locations previously unused in the study and they are used to estimate the return periods of various flows from the lognormal distribution. Application of the Kolmogorov-Smirnov goodness-of-fit test suggests that only one of the five test stations can be considered significantly different from the observed data, confirming the applicability of this technique. 相似文献
162.
以有机污染为主的河流治理技术研究进展 总被引:14,自引:0,他引:14
借鉴国外污染河流治理与修复的经验,并结合我国当前严重的河流污染形势,介绍了以有机污染为主的河流治理技术的研究进展。根据污染河水处理系统与河道的相对空间关系,河流治理技术可分为三类,第一类是将河水引出河道水系,引入附近的污水处理厂进行处理的异地处理法,其中截污工程是异地处理法的关键;第二类是在河道内建设处理系统,沿程进行河水净化的原位处理法,如河道内的曝气法、投菌法、生物膜法和化学法等;第三类是在河岸带上建设处理系统,将河水分流其中进行处理的旁路处理法,如建于河岸上的人工湿地处理系统、氧化塘以及多种形式的生物床或生物反应器等,旁路处理法起着人工强化河岸带的作用,是目前受污染河流治理中值得关注的一条新思路。受污染河流的具体处理方法及空间位置的选择,需要根据实际情况而定。 相似文献
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164.
PU Jiang-ping PU Pei-min HU Chun-hu QIANG Jun-ling PU Jue-xing HUA Ji-kang 《环境科学学报(英文版)》2001,13(2):198-200
IntroductionHongshengChemicalFactoryofXishanCityislocatedintheTaihuLakeBasin(TLB)ofChina.Ithasoneworkshopforproducingacidoidblackandblackbluedyeandacidbrowndye.Thefactoryreleasestwotypesofwastewaterwithvolumeeachfor10t/dduringthefirstandsecondcouplingpr… 相似文献
165.
Ulku?SahinEmail author Osman?N.?Ucan Cuma?Bayat Nam?k?Oztorun 《Environmental Modeling and Assessment》2005,10(2):135-142
Urban air pollution is a growing problem in developing countries. Some compounds especially sulphur dioxide (SO2) is considered as typical indicators of the urban air quality. Air pollution modeling and prediction have great importance in preventing the occurrence of air pollution episodes and provide sufficient time to take the necessary precautions. Recently, various stochastic image-processing algorithms such as Artificial Neural Network (ANN) are applied to environmental engineering. ANN structure employs input, hidden and output layers. Due to the complexity of the problem, as the number of input–output parameters differs, ANN model settings such as the number of neurons of these layers changes. The ability of ANN models to learn, particularly capability of handling large amounts (or sets) of data simultaneously as well as their fast response time, are invariably the characteristics desired for predictive and forecasting purposes. In this paper, ANN models have been used to predict air pollutant parameter in meteorological considerations. We have especially focused on modeling of SO2 distribution and predicting its future concentration in Istanbul, Turkey. We have obtained data sets including meteorological variables and SO2 concentrations from Istanbul-Florya meteorological station and Istanbul-Yenibosna air pollution station. We have preferred three-layer perceptron type of ANN which consists of 10, 22 and 1 neurons for input, hidden and output layers, respectively. All considered parameters are measured as daily mean. The input parameters are: SO2 concentration, pressure, temperature, humidity, wind direction, wind speed, strength of sunshine, sunshine, cloudy, rainfall and output parameter is the future prediction of SO2. To evaluate the performance of ANN model, our results are compared to classical nonlinear regression methods. The over all system finds an optimum correlation between input–output variables. Here, the correlation parameter, r is 0.999 and 0.528 for training and test data. Thus in our model, the trend of SO2 is well estimated and seasonal effects are well represented. As a result, we conclude that ANN is one of the compromising methods in estimation of environmental complex air pollution problems. 相似文献
166.
Weber AH Buckley RL Parker MJ Harvey RP Hamby DM 《Environmental monitoring and assessment》2003,83(3):255-281
The focus of this study is to develop wind data for the SavannahRiver Site (SRS) between 1955 and 1961 to be used in an assessment of estimates of atmospheric dispersion and downwindrisk at the Savannah River Site. In particular, a study of theuncertainties of radioiodine dosimetry from the late 1950sprovides the underlying motivation for developing historicalwindroses at the Savannah River Site (SRS). Wind measurement towers did not exist at the SRS until theearly 1970s. Three relatively simple methods were used to createa 1955–1961 meteorological database for the SRS for a dosereconstruction project. The winds were estimated from onsitemeasurements in the 1990s and National Weather Service (NWS)observations in the 1990s and 1950s using (1) a linear regressionmethod, (2) a similarity theory approach, and (3) a simplestatistical differences method. The criteria for determining success were based on (1) howwell the mean values and standard deviations of the predictedwind speed agree with the known SRS values from the 1990s, (2) the shape of the predicted frequency distribution functions forwind speed, and (3) how closely the predicted windroses resembledthe SRS windrose for the 1990s. The linear regression model's wind speed distribution functionwas broad, flat, and skewed too much toward higher wind speeds.The similarity theory approach produced a wind speed distributionfunction that contained excess predicted speeds in the range 0–1.54 m s-1 (0–3 kts) and had `excluded' bins caused bypredictions being made from integer values of knots in the NWSdata. The distribution function from the mean difference methodwas smooth with a shape like a Weibull distribution with a shapeparameter of 2 and appearedto resemble closely the SRS 1992–1996 distribution.The wind directions for all three methods of approach weresuccessfully based on the mean difference method. It wasdifficult to discern differences among the wind roses produced bythe three methods so the wind speed distribution functions needto be examined in order to make an informed choice for dose reconstruction. 相似文献
167.
168.
Assessment of the Extreme Rainfall Event at Nashville,TN and the Surrounding Region on May 1–3, 2010
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Barry D. Keim William D. Kappel Geoffrey A. Muhlestein Douglas M. Hultstrand Tye W. Parzybok Amanda B. Lewis Edward M. Tomlinson Alan W. Black 《Journal of the American Water Resources Association》2018,54(5):1001-1010
This paper analyzes the May 1–3, 2010 rainfall event that affected the south‐central United States, including parts of Mississippi, Tennessee, and Kentucky. The storm is evaluated in terms of its synoptic setting, along with the temporal distributions, and spatial patterns of the rainfall. In addition, the recurrence interval of the storm is assessed and the implications for hydrologic structure designs are discussed. The event was associated with an upper‐level trough and stationary frontal boundary to the west of the rainfall region, which remained quasi‐stationary for a period of 48 h. Heavy rainfall was produced by two slow‐moving mesoscale convective complexes, combined with abundant atmospheric moisture. Storm totals exceeding 330 mm occurred within a large elongated area extending from Memphis to Nashville. Isolated rainfall totals over 480 mm were reported in some areas, with NEXRAD weather radar rainfall estimates up to 501 mm. An extreme value analysis was performed for one‐ and two‐day rainfall totals at Nashville and Brownsville, Tennessee, as well as for gridded rainfall estimates for the entire region using the Storm Precipitation Analysis System. Results suggest maximum rainfall totals for some durations during the May 1–3, 2010 event exceeded the 1,000‐year rainfall values from National Oceanic and Atmospheric Administration Atlas 14 for a large portion of the region and reached up to 80% of the probable maximum precipitation values for some area sizes and durations. 相似文献
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170.
Paula Saikkonen 《Local Environment》2013,18(8):888-903
The article focuses on the administrative processes and factors that have been constructing polluted soil as an environmental problem on the local level. The main questions are how polluted soil was constructed as an environmental problem and by whom? The research material consists of documents from the municipality's administration, and the method of analysis is qualitative content analysis. Finally, it is argued that the definition of the problem radically changed in 20 years. However, there was a noticeable institutional delay between the national- and local-level decision-making and some randomness seemed to be involved in the process of understanding and defining the environmental problem. 相似文献