首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   2456篇
  免费   157篇
  国内免费   356篇
安全科学   311篇
废物处理   87篇
环保管理   410篇
综合类   1255篇
基础理论   222篇
环境理论   1篇
污染及防治   247篇
评价与监测   155篇
社会与环境   259篇
灾害及防治   22篇
  2024年   9篇
  2023年   46篇
  2022年   89篇
  2021年   112篇
  2020年   131篇
  2019年   90篇
  2018年   70篇
  2017年   95篇
  2016年   112篇
  2015年   109篇
  2014年   125篇
  2013年   188篇
  2012年   171篇
  2011年   209篇
  2010年   124篇
  2009年   160篇
  2008年   129篇
  2007年   140篇
  2006年   130篇
  2005年   111篇
  2004年   72篇
  2003年   91篇
  2002年   69篇
  2001年   63篇
  2000年   53篇
  1999年   53篇
  1998年   41篇
  1997年   36篇
  1996年   33篇
  1995年   21篇
  1994年   25篇
  1993年   16篇
  1992年   11篇
  1991年   2篇
  1990年   8篇
  1989年   3篇
  1988年   2篇
  1987年   4篇
  1986年   2篇
  1985年   1篇
  1984年   1篇
  1983年   2篇
  1982年   1篇
  1981年   1篇
  1979年   3篇
  1978年   2篇
  1973年   1篇
  1970年   1篇
  1968年   1篇
排序方式: 共有2969条查询结果,搜索用时 15 毫秒
171.
山西潞安集团充分发挥自身煤炭资源和区位发展优势,以煤的深度转化为主线,着力探索实践煤基合成油项目,延伸发展煤基多联产产业化,产出了煤基合成油,建成了煤油循环经济园区,走出一条“高碳能源,低碳利用”的循环经济之路。对潞安集团煤油循环经济园区进行全面的研究和介绍,以期为煤炭工业可持续发展提供一种全新的视角和思路。  相似文献   
172.
在脱硫脱硝喷淋装置上采用氨法-络合法处理工业烟气。考察了吸收液pH、Fe(Ⅱ)EDTA浓度、初始烟气浓度、液气比对烟气同时脱硫脱硝效果的影响。实验结果表明:吸收液的酸碱度通过影响Fe(Ⅱ)与EDTA的络合形式进而影响NO去除率;SO_2去除率主要受吸收液pH和初始SO_2质量浓度的影响;当吸收液pH大于8、吸收液Fe(Ⅱ)EDTA浓度大于0.100 mol/L、初始SO_2质量浓度小于1 500 mg/m3、初始NO质量浓度为1 200 mg/m3时,SO_2去除率均在95%以上,NO去除率为54%;当液气比由1 L/m3增大至4 L/m3时,有效脱硫时间和有效脱硝时间分别增长了7 min和4 min。  相似文献   
173.
Few studies have evaluated how effectively environmental contamination may reduce genetic diversity of a population. Here, we chose a laboratory approach in order to test if tributyltin (TBT) exposure at environmentally relevant concentrations leads to reduced genetic variation in the midge Chironomus riparius. Two TBT-exposed and two unexposed experimental populations were reared simultaneously in the laboratory for 12 generations. We recorded several life-history traits in each generation and monitored genetic variation over time using five variable microsatellite markers. TBT-exposed strains showed increased larval mortality (treatments: 43.8%; controls: 27.8%), slightly reduced reproductive output, and delayed larval development. Reduction of genetic variation was strongest and only significant in the TBT-exposed strains (treatments: −45.9%, controls: −24.4% of initial heterozygosity) after 12 generations. Our findings document that chemical pollution may lead to a rapid decrease in genetic diversity, which has important implications for conservation strategies and ecological management in polluted environments.  相似文献   
174.
Lignocellulosic materials are good precursors for the production of activated carbon. In this work, coffee residue has been used as raw material in the preparation of powder activated carbon by the method of chemical activation with zinc chloride for the sorption of Pb(II) from dilute aqueous solutions.The influence of impregnation ratio (ZnCl2/coffee residue) on the physical and chemical properties of the prepared carbons was studied in order to optimize this parameter. The optimum experimental condition for preparing predominantly microporous activated carbons with high pore surface area (890 m2/g) and micropore volume (0.772 cm3/g) is an impregnation ratio of 100%. The developed activated carbon shows substantial capability to sorb lead(II) ions from aqueous solutions and for relative impregnation ratios of 75 and 100%, the maximum uptake is practically the same. Thus, 75% represents the optimal impregnation ratio.Batch experiments were conducted to study the effects of the main parameters such as contact time, initial concentration of Pb(II), solution pH, ionic strength and temperature. The maximum uptake of lead(II) at 25 °C was about 63 mg/g of adsorbent at pH 5.8, initial Pb(II) concentration of 10 mg/L, agitation speed of 200 rpm and ionic strength of 0.005 M. The kinetic data were fitted to the models of pseudo-first order and pseudo-second order, and follow closely the pseudo-second order model. Equilibrium sorption isotherms of Pb(II) were analyzed by the Langmuir, Freundlich and Temkin isotherm models. The Freundlich model gives a better fit than the others.Results from this study suggest that activated carbon produced from coffee residue is an effective adsorbent for the removal of lead from aqueous solutions and that ZnCl2 is a suitable activating agent for the preparation of high-porosity carbons.  相似文献   
175.
Long-term consumption of water containing excessive fluoride can lead to fluorosis of the teeth and bones. Electrocoagulation (EC) is an electrochemical technique, in which a variety of unwanted dissolved particles and suspended matter can be effectively removed from an aqueous solution by electrolysis. Continuous flow experiments with monopolar aluminium electrodes for fluoride removal were undertaken to investigate the effects of the different parameters such as: current density (12.5-50A/m(2)), flow rate (150-400 mL/min), initial pH (4-8), and initial fluoride concentration (5-25mg/L). The highest treatment efficiency was obtained for the largest current and the removal efficiency was found to be dependent on the current density, the flow rate and the initial fluoride concentration when the final pH ranged between 6 and 8. The composition of the sludge produced was analysed using the X-ray diffraction (XRD) spectrum. The strong presence of the aluminium hydroxide [Al(OH)(3)] in the above pH range, which maximizes the formation of aluminium fluoride hydroxide complex [Al(n)F(m)(OH)(3n-m)], is the main reason for defluoridation by electrocoagulation. The results obtained showed that the continuous flow electrocoagulation technology is an effective process for defluoridation of potable water supplies and could also be utilized for the defluoridation of industrial wastewater.  相似文献   
176.
The hydrolysis/precipitation behaviors of Al3+, Al13 and Al30 under conditions typical for flocculation in water treatment were investigated by studying the particulates' size development, charge characteristics, chemical species and speciation transformation of coagulant hydrolysis precipitates. The optimal pH conditions for hydrolysis precipitates formation for AlCl3, PACAl13 and PACAl30 were 6.5–7.5, 8.5–9.5, and 7.5–9.5, respectively. The precipitates' formation rate increased with the increase in dosage, and the relative rates were AlCl3 ? PACAl30 > PACAl13. The precipitates' size increased when the dosage increased from 50 μM to 200 μM, but it decreased when the dosage increased to 800 μM. The Zeta potential of coagulant hydrolysis precipitates decreased with the increase in pH for the three coagulants. The iso-electric points of the freshly formed precipitates for AlCl3, PACAl13 and PACAl30 were 7.3, 9.6 and 9.2, respectively. The Zeta potentials of AlCl3 hydrolysis precipitates were lower than those of PACAl13 and PACAl30 when pH > 5.0. The Zeta potential of PACAl30 hydrolysis precipitates was higher than that of PACAl13 at the acidic side, but lower at the alkaline side. The dosage had no obvious effect on the Zeta potential of hydrolysis precipitates under fixed pH conditions. The increase in Zeta potential with the increase in dosage under uncontrolled pH conditions was due to the pH depression caused by coagulant addition. Al–Ferron research indicated that the hydrolysis precipitates of AlCl3 were composed of amorphous Al(OH)3 precipitates, but those of PACAl13 and PACAl30 were composed of aggregates of Al13 and Al30, respectively. Al3+ was the most un-stable species in coagulants, and its hydrolysis was remarkably influenced by solution pH. Al13 and Al30 species were very stable, and solution pH and aging had little effect on the chemical species of their hydrolysis products. The research method involving coagulant hydrolysis precipitates based on Al–Ferron reaction kinetics was studied in detail. The Al species classification based on complex reaction kinetic of hydrolysis precipitates and Ferron reagent was different from that measured in a conventional coagulant assay using the Al–Ferron method. The chemical composition of Ala, Alb and Alc depended on coagulant and solution pH. The Alb measured in the current case was different from Keggin Al13, and the high Alb content in the AlCl3 hydrolysis precipitates could not used as testimony that most of the Al3+ was converted to highly charged Al13 species during AlCl3 coagulation.  相似文献   
177.
Forecasting the outbreak of moorland wildfires in the English Peak District   总被引:1,自引:0,他引:1  
Warmer, drier summers brought by climate change increase the potential risk of wildfires on the moorland of the Peak District of northern England. Fires are costly to fight, damage the ecosystem, harm water catchments, cause erosion scars and disrupt transport. Fires release carbon dioxide to the atmosphere. Accurate forecasts of the timing of fires help deployment of fire fighting resources.  相似文献   
178.
Effects of acute γ-irradiation were investigated in the aquatic microcosm consisting of green algae (Chlorella sp. and Scenedesmus sp.) and a blue–green alga (Tolypothrix sp.) as producers; an oligochaete (Aeolosoma hemprichi), rotifers (Lecane sp. and Philodina sp.) and a ciliate protozoan (Cyclidium glaucoma) as consumers; and more than four species of bacteria as decomposers. At 100 Gy, populations were not affected in any taxa. At 500–5000 Gy, one or three taxa died out and populations of two or three taxa decreased over time, while that of Tolypothrix sp. increased. This Tolypothrix sp. increase was likely an indirect effect due to interspecies interactions. The principal response curve analysis revealed that the main trend of the effects was a dose-dependent population decrease. For a better understanding of radiation risks in aquatic microbial communities, effect doses of γ-rays compared with copper, herbicides and detergents were evaluated using the radiochemoecological conceptual model and the effect index for microcosm.  相似文献   
179.
The establishment and development of the industrial symbiosis of eco-industrial park are affected by several factors. Based on the formed industrial symbiosis supporting system chart, this article analyzes the microcosmic supporting system and macroscopic supporting system. In the microcosmic supporting system, it elaborates five aspects including key enterprises, service intermediaries in the park, symbiotic enterprises, competitors and the public in detail. Then it describes the macroscopic supporting system from four aspects of governmental participation, technological innovation, educational promotion and cultural support. Finally, combining with the current construction status of the ecoindustrial park in China, it proposes the countermeasures and suggestions to build the supporting system for the eco-industrial park and provides theoretical support for the faster and better construction of the eco-industrial park in China.  相似文献   
180.
To estimate the response of conifers to long-term industrial air pollution at the pigment system level, the dynamics of photosynthetic pigments have been studied in needles of Scots pine (Pinus sylvestris L.) and Siberian spruce (Picea obovata Ledeb.) growing at different distances from the emission source (a pulp and paper mill). It has been shown that the pigment apparatus of spruce. The results show that in spruce, unlike in pine, the pigment apparatus remains unchanged under the effect of weak pollution. Long-term exposure at high levels of industrial emission results in suppression of chlorophyll and carotenoid syntheses in pine but stimulates pigment production in spruce. An increase in the contents of pigments in the needles of conifers growing in the impact zone of the pulp and paper mill reflects a compensatory mechanism of adaptation of their pigment system to long-term stress exposure.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号