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1.
Abstract

The growing amount of rubber waste, such as that from tires and cables, has resulted in serious environmental problems. Since rubber waste is not easily biodegradable even after a long period of landfill treatment, material and energy recovery is the preferable alternative to disposal. The potential offered by waste tire pyrolysis for solving both energy and waste treatment problems is widely recognized. Pyrolysis is one method of inducing thermal decomposition without using any oxidizing agent, or using such a limited supply of the agent that oxidization does not proceed to an appreciable extent. The latter may be described as autothermal pyrolysis and will be studied in the present work.

The main objective of this research was to study the operating parameters of autothermal pyrolysis of scrap tires in a laboratory-scale fluidized bed reactor with a 100-cm bed height (10 cm I.D.) and a 100-cm freeboard (25 cm I.D.). Scrap tires were pyrolyzed in a limited oxygen supply, so that the heat for pyrolysis of the scrap tires was provided by combustion of some portion of the scrap tires. The operating parameters evaluated included the effect on the pyrolysis oil products and their relative proportions of (1) the air factor (O.O7–O35); (2) the pyrolysis temperature (370–570 °C); and (3) the catalyst added (zeolite and calcium carbonate). The results show that: (1) the composition of the liquid hydrocarbon obtained is affected significantly by the air factor; (2) the higher operating temperature caused a higher yield of gasoline and diesel; (3) the yield of gasoline increased due to the catalyst zeolite added, and the yield of diesel increased due to the addition of the catalyst calcium carbonate; (4) the principal constituents of gasoline included dipentene and diprene.  相似文献   
2.
Identification and quantification of dissolved oxygen (DO) profiles of river is one of the primary concerns for water resources managers. In this research, an artificial neural network (ANN) was developed to simulate the DO concentrations in the Heihe River, Northwestern China. A three-layer back-propagation ANN was used with the Bayesian regularization training algorithm. The input variables of the neural network were pH, electrical conductivity, chloride (Cl?), calcium (Ca2+), total alkalinity, total hardness, nitrate nitrogen (NO3-N), and ammonical nitrogen (NH4-N). The ANN structure with 14 hidden neurons obtained the best selection. By making comparison between the results of the ANN model and the measured data on the basis of correlation coefficient (r) and root mean square error (RMSE), a good model-fitting DO values indicated the effectiveness of neural network model. It is found that the coefficient of correlation (r) values for the training, validation, and test sets were 0.9654, 0.9841, and 0.9680, respectively, and the respective values of RMSE for the training, validation, and test sets were 0.4272, 0.3667, and 0.4570, respectively. Sensitivity analysis was used to determine the influence of input variables on the dependent variable. The most effective inputs were determined as pH, NO3-N, NH4-N, and Ca2+. Cl? was found to be least effective variables on the proposed model. The identified ANN model can be used to simulate the water quality parameters.  相似文献   
3.
Circular economy (CE), with its basic principle of Reduce, Reuse, and Recycle, has been determined as the key strategy for the national development plan by the Chinese government. Given the economy-wide material flow analysis (EW-MFA) that leaves the inner flow of resource reutilisation unidentified, the reutilisation-extended EW-MFA is first introduced to evaluate and analyse the material input, solid waste generation, and reutilisation simultaneously. The total amount of comprehensive reutilisation (CR) is divided into three sub-flows, namely, reutilisation, recycle, and reuse. Thus, this model is used to investigate the resource CR in China from 2000 to 2010. China’s total amount of CR and its sub-flows, as well as the CR rate, remain to have a general upward trend. By the year 2010, about 60% of the overall solid waste generation had already been reutilised, and more than 20% of the total resource requirement was reutilised resource. Moreover, the growth patterns of the CR sub flows show different characteristics.Interpretations of resource reutilisation-related laws and regulations of CE and the corresponding policy suggestions are proposed based on the results.  相似文献   
4.
Residues from the imported wastes dismantling process create a great burden on the ambient environment. To develop appropriate strategies for the disposal of such residues, their characteristics were studied through background value analysis and toxicity leaching tests. Our results showed that the heavy metals concentrations in residues were high, particularly those of Cu (7180 mg kg?1), Zn (2783 mg kg?1), and Pb (1954 mg kg?1). Toxicity leaching tests revealed a high metal releasing risk of such residues if they are disposed of in a landfill. However, the residues of imported wastes were also found to have some intrinsic metal recycling value.  相似文献   
5.
"两型"社会的建设为低碳经济的发展、实施提出了明确的方向,也为企业的可持续发展指明了道路。文章在分析借鉴国际大石油公司低碳发展实践经验的基础上,对我国低碳经济发展现状、石油企业面对低碳发展环境的机遇和挑战进行了系统分析,并对我国石油企业低碳发展的总体思路、模式设计提出了建议。  相似文献   
6.
用喷雾干燥和表面吸附固定化两种工艺对石油降解菌剂进行固态菌研制。结果表明:在对菌浓度为9.7×109 cfu/mL的500mL发酵液添加40g轻质碳酸钠后进行喷雾干燥,在进风温度为120℃,进样量为12mL/min的条件下,得到粉剂产品56g,含水量为4.6%,菌密度为10.05×109 cfu/g,产品得率为11.6%;在对菌浓度为9.7×109 cfu/mL的500mL发酵液添加1 500g麸皮进行吸附固定化处理,得到粉剂产品1 438.6g,水分含量为7.9%,菌密度为5.7×108 cfu/g,产品得率为16.9%。考虑到喷雾工艺设备投资大,能耗多等不利因素,因此建议使用吸附固定化技术作为石油降解固态菌剂的下游处理技术。  相似文献   
7.
研究了一种石油降解菌群的固定化方法,其中菌群包括假单胞菌、芽孢杆菌和微球菌。以硅藻土/活性炭作为降解菌群的固定化载体,对最佳固定化条件进行研究,结果表明:降解菌群的最佳固定化时间16h,温度37℃,硅藻土/活性炭加入量0.1g/mL,pH值7.5,120r/min振荡16h,降解菌群固定化率达97.1%。固定化菌群用于油基钻屑中油降解,降解14d,可使钻屑中TPH含量由30 000mg/kg降至10 450mg/kg,平均油去除率达65%。  相似文献   
8.
Reconstructions of historical cropland area and spatial distribution are necessary for studying human effects on the environment due to agricultural development. To understand the current status of reconstructions of cropland area and its spatial distribution in the mid-eleventh century in the traditional agricultural area of China, we compared three available datasets: the historic cropland inventories-based HE dataset, the population-based History Database of the Global Environment (HYDE) dataset, and the PJ dataset. The results indicate that the HYDE and PJ datasets estimated the regional mean cropland area fraction (a ratio of cropland area to total land area, hereafter, CAF) for the study area to be 0.12 and 0.09, respectively, both of which were lower than the HE estimation of 0.18. Moreover, both the HYDE and PJ datasets have a poor ability to capture the spatial distribution of the historical CAF. The HYDE dataset overestimated the cropland area in North China and underestimated the cropland area in the Yangtze River reach. The HYDE dataset also overestimated the cropland area along the great rivers in North China. The PJ dataset underestimated the cropland area in the old agricultural area and overestimated the cropland area in the relatively new agricultural area. These incorrect spatial distributions from the HYDE and PJ datasets mainly resulted from the underestimation of the historical population and an incorrect approach for the spatial allocation of cropland within China. The incorrect approach was mainly derived from a poor understanding of the historic spatial distribution of cropland. Using the expert knowledge of local historians may be an effective method to reduce the uncertainties in the global historic cropland reconstruction.  相似文献   
9.
Organochlorine pesticides (OCPs) were analyzed in 26 surface sediment samples from the Liaohe River basin, and the distributions of and potential environmental risks posed by OCPs in the basin were evaluated. Eighteen OCPs listed in the Stockholm Convention were determined using isotope-dilution gas chromatography–high resolution mass spectrometry. This is the first study of hexachlorobenzene (HCB) in the Liaohe River basin sediments. The total OCP concentrations were 0.39–68.06 ng g?1 dry weight. The total α-, β-, γ-, and δ-hexachlorocyclohexane (HCH), the total dichlorodiphenyltrichloroethane (DDT – p,p′-dichlorodiphenyldichloroethane (DDD), p,p′-dichlorodiphenyldichloroethylene (DDE), o,p'-DDT, and p,p′-DDT), and the HCB concentrations in the sediment samples were 0.1–28.48 ng g?1 (mean 4.01 ng g?1), 0.08–6.52 ng g?1 (mean 3.07 ng g?1), and 0.18–24.8 ng g?1 (mean 4.38 ng g?1), respectively. The HCB concentrations were higher than the concentrations of the other OCPs, and the HCHs and HCB together were the dominant OCPs. β-HCH was the most abundant HCH isomer. The concentrations of DDTs and other OCPs were relatively low, and the (DDE+DDD)/DDT ratios (>0.5) and DDD/DDE ratios (<1) indicated that no recent DDT inputs had occurred in the Liaohe River system. The main sources of HCHs were probably the historical production and agricultural use of HCH in the study area. The DDT and HCH concentrations were generally below or similar to the concentrations that have been found in other parts of the world. An ecotoxicological evaluation indicated that HCHs in surface sediments pose slight risks to human and ecological health in the Liaohe River basin.  相似文献   
10.
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