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101.
102.
Iloweka EM 《Environmental monitoring and assessment》2004,99(1-3):245-250
The Lower Congo is one of eleven provinces in the Democratic Republic of Congo, and is located southwest of Kinshasa Town
Province. It has an area of approximately 53.947 km2 with a population of 1 504 361 at an estimated 237 persons per km2. The Province comprises five districts, including Lukaya and Cataracts where rural poverty is severe and the population struggle
to make a living through agriculture and woodcutting. These activities result in excessive resource exploitation. The high
demand for foodstuffs and the high consumption of wood (for energy, construction and export) in Kinshasa, the capital city
of the Democratic Republic of Congo and the expanding towns of Matadi and Boma in the Lower Congo Province, are speeding the
deforestation rate and unbalancing forest ecosystems. In addition there is the stress resulting from reduced josher (the rest period for agriculture ground), plus climate change and erosion. The phenomena that that we need to address in
these two districts include deforestation, reduced josher, excessive agriculture, erosion, burning and climate change which
taken together largely explain the current soil degradation. These areas are marked by excessive post deforestation savannah
formation and extended areas of sandy soil, distributed throughout grass and shrub savannahs. This desertification, which
is rampant in Lukaya and Cataracts, risks imprisoning the rural population in a vicious cycle of poverty if adequate solutions
are not found. 相似文献
103.
J. Ernest Flack 《Journal of the American Water Resources Association》1980,16(1):139-141
ABSTRACT: Increasing costs and competition for water have resulted in pressure to manage urban water demand through conservation programs. Metering, pricing, devices, restrictions, building code changes, and horticultural practices have all been effective in reducing average residential water use. Some conservation means are specifically aimed at reducing peak demands but these usually reduce average usage as well. Combined programs of conservation can be expected to reduce urban demand by as much as 25–30 percent over the long term. Restrictions can reduce water usage on the short term even further. The success of conservation programs is as dependent on the effectiveness of public education and information dissemination as on the conservation practices themselves. 相似文献
104.
Genetic Analyses to Establish Captive Breeding Priorities for Endangered Snake River Sockeye Salmon 总被引:3,自引:0,他引:3
Shawn A. Cummings Ernest L. Brannon Karen J. Adams & Gary H. Thorgaard 《Conservation biology》1997,11(3):662-669
The plight of the Snake River sockeye salmon presents a challenging genetic puzzle for conservation biologists. Although the Snake River sockeye has been declared endangered, assessment of captive breeding strategies are complicated because a healthy non-migratory strain of O. nerka (kokanee) resides in Redfish Lake, Idaho—the same lake the anadromous fish return to for spawning. The migration of 1-year-old fish (outmigrants) from the lake each year and the observation of non-migratory fish spawning in areas previously used by the sockeye further complicate the issue. We estimated the relatedness of these strains by direct examination of their genetic similarity. Mixed DNA fingerprint analyses suggested that the outmigrants were more closely related to the anadromous sockeye than to the kokanee. Closer analysis using a probe, One-HO.8, to examine allele frequencies at a single locus revealed polymorphism in a number of O. nerka populations. Within the Redfish Lake populations this probe detected an allele present at 0.21 frequency in the kokanee (n = 43), 0.01 (n = 324) in the outmigrants, and absent among 13 anadromous fish. These results support a close genetic relationship of the outmigrants to the anadromous sockeye and the probable utility of the outmigrants in a captive breeding program to restore the anadromous strain. 相似文献
105.
Ernest M. Thiessen Daniel P. Loucks 《Journal of the American Water Resources Association》1992,28(1):163-177
ABSTRACT: Since the early 1970s, a large volume of literature has accumulated related to multiobjective water resources management problems. A relatively small portion of this specifically addresses the negotiation process required when there are multiple decision makers with conflicting objectives. This paper focuses on that process and describes a computer program designed to assist such negotiation processes. This interactive computer assisted negotiation support system is called ICANS. ICANS is designed for dynamic, multi-issue, multi-party negotiation problems. Based on information provided in confidence by each party via an interactive graphical interface, the program can help determine if there exist any possible alternatives that are equivalent or even preferred to each party's decision in the absence of a negotiated agreement. If such alternatives exist, through a series of iterations in which each party's input data, assumptions, and preferences may change, ICANS can assist the parties in their search for a mutually acceptable and preferred agreement. A simple example illustrates the data requirements and the use of ICANS in negotiation experiments. 相似文献
106.
This article describes the development, use, and learning from a Business Tailored Management System Verification (BTMSV) process. This process is designed to focus on selected Responsible Care activities or programs, and provides broad options to include specific elements to meet more targeted business unit objectives. © 1998 John Wiley & Sons, Inc. 相似文献
107.
Chihuahuan Desert kangaroo rats: nonlinear effects of population dynamics, competition, and rainfall 总被引:1,自引:0,他引:1
Using long-term data on two kangaroo rats in the Chihuahuan Desert of North America, we fitted logistic models including the exogenous effects of seasonal rainfall patterns. Our aim was to test the effects of intraspecific interactions and seasonal rainfall in explaining and predicting the numerical fluctuations of these two kangaroo rats. We found that logistic models fit both data sets quite well; Dipodomys merriami showed lower maximum per capita growth rates than Dipodomys ordii, and in both cases logistic models were nonlinear. Summer rainfall appears to be the most important exogenous effect for both rodent populations; models including this variable were able to predict independent data better than models including winter rainfall. D. merriami was also negatively affected by another kangaroo rat (Dipodomys spectabilis), consistent with previous experimental evidence. We hypothesized that summer rainfall influences the carrying capacity of the environment by affecting seed availability and the intensity of intraspecific competition. 相似文献
108.
109.
110.
Sewage sludge from four publicly-owned treatment works was sampled and characterized in terms of parameters affecting transport at the 106-mile deep ocean disposal site as part of the US Environmental Protection Agency's site monitoring programme. Samples from treatment plants in Passaic Valley, Rahway, and Elizabeth, New Jersey and New York City were characterized in terms of dynamic size distribution, suspended solids and density. the transport characteristics of sludge particles were measured using a 2 metre computer-interfaced laboratory settling column. Experiments were conducted at constant salinity (35 ppt) while varying hydrodynamic mixing, sludge type and concentration using a modified factorial experimental design. Hydrodynamic power dissipation was varied so that the vertical dispersion and rms fluid shear rate ranged between 0-6 cm2S-1 and 0-30s-1 respectively. Results indicate that at least 80% of suspended sludge particles will eventually settle under mixed conditions. the average settling velocities ranged between 0.05-4.05 × 10-3 cm s-1. Shear rates above 15 s-1 inhibited sludge settling due to aggregate breakup and boundary effects, but at a lower shear rate, differential settling and fluid shear were the dominant transport mechanisms. Sludge dilution (1/500-1/5000) had a limited effect on the settling rate. Results from this study can be used to calibrate particle transport models to determine the fate of sludge disposed at an ocean disposal site. 相似文献