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921.
The United States Environmental Protection Agency's Environmental Monitoring and Assessment Program (EMAP) will monitor the nation's resources by evaluating the status and trends of selected indicators of condition using a probability-based sampling design. The EMAP-Wetlands program will monitor the condition of the nation's wetlands. The EMAP classification system is an aggregation of the many subclasses of the US Fish and Wildlife Service's National Wetlands Inventory (NWI) classification system. This aggregation results in fewer wetland classes with more wetlands per class than the NWI system. Aggregation of the NWI classification was based primarily on dominant vegetation cover, flooding regimes, dominant water source, and adjacency to rivers and lakes. We evaluated the EMAP classification system and sampling design using NWI digital wetlands data for portions of Illinois, Washington, North Dakota, and South Dakata. Relative numbers of wetlands, total areas, average areas, and common versus rare classes were compared between the EMAP and NWI classification systems. As expected, the EMAP classification provided fewer wetland polygons, each with larger areas, without altering total wetland area. Summary statistics comparing sample estimates to true population parameters (represented by the NWI data) demonstrated the effectiveness of the EMAP sampling design with the exception of rare EMAP classes in the selected regions. Although simple random sampling is inadequate for both large and small wetlands, the EMAP sampling design is readily adapted to provide better estimates for these categories. Aggregating the NWI classification to the EMAP classification provides fewer wetland classes, with more wetlands per class, for EMAP's annual reports and statistical summaries. The research in this report has been funded by the United States Environmental Protection Agency (EPA) under contracts 68-C8-0006 to ManTech Environmental Technology, Inc. and 68-03-3532 to The Bionetics Corporation. Mention of trade names does not constitute endorsement or recommendation for use.  相似文献   
922.
The Environmental Auditing Roundtable (EAR) is the single largest professional organization in the world, representing over 900 members. Built on a tradition of promoting environmental auditing through openly sharing experiences in the field of safety, health, and environmental auditing, the organization in recent years has significantly expanded its influence on auditing practices both nationally and internationally by monitoring audit activities and participating in the development of audit policy, regulation, standardization, and the certification of environmental auditors. This article describes the origin and evolution of the organization from meeting the needs of the membership to addressing the needs of external national and international stakeholders.  相似文献   
923.
ABSTRACT: A study was conducted to derive a simple procedure for estimating the tributary drainage area that may potentially develop at the base of a uniformly graded, steep slope. Data were extracted from a nil development flume study in which 112 rills and their tributary drainage areas were documented. The tributary drainage area for each rill was correlated to the slope length and the slope gradient. The findings are considered applicable to planar, convex, and divergent slopes with lengths of up to 130 m. Field verification is needed to extend the applicability of the relation.  相似文献   
924.
ABSTRACT: Different allocation and delivery performance ratios are used to assess operations performance in a large scale public irrigation system in Indonesia. Results from this analysis indicate that field management practices deviate substantially from the official operating procedures. The lack of application of a single, standardized procedure for planning water allocations represents a serious constraint to effective monitoring and evaluating system performance. Underestimated and unrealistic planned allocations becomes the justification for overdiversion of water, and has the effect of undermining the resolve of managers to see to it that actual flows meet planned flows. Miscalculating planned allocations, poor matches between planned flows and actual deliveries, overdiversion and misreporting have economic consequences as well. For example, strict adherence to the standard operating rule during the second dry season of 1987 would have resulted in 19,070,000 m3 less water diverted into the irrigation system from the Brantas River or, at a conservative estimate of $1.78 per 100 m3 water, a savings of $339,500. Scope exists for making improvements in management by closer adherence to the standard delivery rule, which will also facilitate proper monitoring and evaluation.  相似文献   
925.
Many Superfund or hazardous waste sites prove to be excellent candidates for remediation using transportable incineration. Transportable incineration has been selected as the alternative of choice to remediate numerous sites throughout the United States. There are a number of firms that provide mobile and transportable incineration equipment and services. A variety of treatment systems are available, including rotary kilns, fluidized beds, and infrared incinerators. Roy F. Weston, Inc., has been instrumental in the development, design, permitting, construction, performance testing, and operation of hazardous and toxic waste thermal treatment systems. Weston owns and operates two high-temperature transportable incineration systems (TISs). The first system is Weston's seven-ton-per-hour (tph) TIS-5. The second is the TIS-20, with a design capacity of up to 30 tph. These units are typical rotary kiln incinerators, the most flexible, adaptable type of incineration unit. This article discusses Weston's use of these incinerators to remediate soils at sites contaminated with polychlorinated biphenyls (PCBs).  相似文献   
926.
ABSTRACT: Two major objectives in operating the multireservoir system of the Upper Colorado River basin are maximization of hydroelectric power production and maximization of the reliability of annual water supply. These two objectives conflict. Optimal operation of the reservoir system to achieve both is unattainable. This paper seeks the best compromise solution for an aggregated reservoir as a surrogate of the multireservoir system by using two methods: the constraint method and the method of combined stochastic and deterministic modeling. Both methods are used to derive the stationary optimal operating policy for the aggregated reservoir by using stochastic dynamic programming but with different objective functions and minimum monthly release constraints. The resulting operating policies are then used in simulated operation of the reservoir with historical inflow records to evaluate their relative effectiveness. The results show that the policy obtained from the combination method would yield more hydropower production and higher reliability of annual water supply than that from the constraint-method policy.  相似文献   
927.
ABSTRACT: Topographic maps are commonly used to define populations of lakes in regional surveys of surface water quality. To illustrate the effect of different maps on that process, we compared the lakes represented on the 1:250,000-scale maps used for the Northeast Region of the Eastern Lake Survey—Phase I (ELS-I) to the lakes on a sample of large-scale maps (1:24,000 or 1:62,500). Lake areas at or near the lower limit of representation delimited “smallest-lake” values for the compared 1:250,000-scale maps. The regional median for these values was 4.5 hectares (ha) and ranged from 0.6 to 24.8 ha. Lake representation is influenced by cartographic limitations such as map scale, age, and complexity as well as the inherent variability of waterbodies (e.g., water level fluctuations or the creation of reservoirs, beaver impoundments, and oxbows). The total number of lakes on large-scale maps increased markedly as lake area decreased. Approximately 15,700 of the estimated 29,000 lakes in the EPA's Northeast Region were 1 to 4 ha in area. Because maps affect the size distribution of lakes included in a regional survey and because lake areas are thought to modify lake chemistry, maps ultimately affect the estimates of regional surface water quality.  相似文献   
928.
929.
A relatively simple Gaussian-type diffusion simulation model for calculating urban carbon monoxide (CO) concentrations as a function of local meteorology and the distribution of traffic is described. The model can be used in two ways: (1) in the synoptic mode, in which hourly concentrations at one or many receptor points are calculated from historical or forecast traffic and meteorological data; and (2) in the climatological mode, in which concentration frequency distributions are calculated on the basis of long-term sequences of input data. For model evaluation purposes, an extensive field study involving meteorological and air-quality measurements was conducted during November-December 1970 in San Jose, Calif., which has an automated network to provide traffic data throughout the central business district. Model refinements made on the basis of the data from this experimental program include the addition of a street-canyon submodel to compensate for the important aerodynamic effects of buildings on CO concentrations at streetside receptors. The magnitude of these effects was underscored by the concentrations measured on opposite sides of the street in San Jose, which frequently differed by a factor of two or more. Evaluation of the revised model has shown that calculated and observed concentration frequency distributions for street-canyon sites are in good agreement. Hour-average predictions are well correlated with observations (correlation coefficient of about 0.6 to 0.7), and about 80 percent of the calculated values are within 3 ppm of the observed hour-average concentrations, which ranged as high as 16 ppm.  相似文献   
930.
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