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   1753篇
  免费   18篇
  国内免费   43篇
安全科学   31篇
废物处理   117篇
环保管理   182篇
综合类   158篇
基础理论   323篇
环境理论   2篇
污染及防治   576篇
评价与监测   314篇
社会与环境   107篇
灾害及防治   4篇
  2023年   63篇
  2022年   175篇
  2021年   118篇
  2020年   25篇
  2019年   46篇
  2018年   86篇
  2017年   92篇
  2016年   112篇
  2015年   46篇
  2014年   82篇
  2013年   188篇
  2012年   88篇
  2011年   96篇
  2010年   79篇
  2009年   63篇
  2008年   78篇
  2007年   61篇
  2006年   72篇
  2005年   40篇
  2004年   27篇
  2003年   21篇
  2002年   31篇
  2001年   11篇
  2000年   8篇
  1999年   8篇
  1998年   4篇
  1996年   7篇
  1994年   5篇
  1993年   4篇
  1992年   3篇
  1991年   2篇
  1989年   5篇
  1988年   3篇
  1985年   3篇
  1984年   3篇
  1983年   5篇
  1982年   6篇
  1980年   2篇
  1979年   3篇
  1978年   4篇
  1969年   2篇
  1965年   3篇
  1964年   2篇
  1962年   2篇
  1961年   5篇
  1960年   2篇
  1958年   3篇
  1957年   3篇
  1956年   3篇
  1955年   4篇
排序方式: 共有1814条查询结果,搜索用时 31 毫秒
41.
The phototransformation of Oryzalin was studied under UV light (λmax ≥ 290 nm) and sunlight (λmax ≥ 250 nm) in aqueous isopropanol and acetonitrile solution in absence and presence of TiO2 as sensitizer. The rate of photodegradation of Oryzalin in different solvent system followed first-order kinetics, and calculated half-lives were found to be in the range of 23.52-53.75 h for UV light and 41.23-61.43 h for sunlight. From this study, total 12 photoproducts were identified and characterized on the basis of column chromatography and Q-Tof micromass spectral data. The plausible mechanism of phototransformation involved was hydrolysis, breaking of sulfonic bond, and loss of amino and sulfonic acid group.  相似文献   
42.
Environmental toxicants viz lead or cadmium and phthalate esters (di(2-ethylhexyl) phthalate [DEHP], dibutyl phthalate [DBP], and diethyl phthalate [DEP]) widely found in different environmental strata are linked to deteriorating male reproductive health. The objective was to assess the relationships between the seminal lead, cadmium, and phthalate (DEHP, DBP, DEP) concentrations at environmental level and serum hormone levels and semen quality in non-occupationally exposed men and specify the effect of individual and combined exposure of toxicants on semen quality. A study of 60 male partners of couples attending the Andrology Laboratory of the Reproductive Biology Department, All India Institute of Medical Sciences (AIIMS), New Delhi, India for semen analysis to assess their inability to achieve a pregnancy was selected for the study. The results of univariate and stepwise multiple regression analysis in the unadjusted model showed a significant correlation between lead or cadmium and phthalates DEHP/DBP/DEP and sperm motility, sperm concentration, and DNA damage. After adjusting for potential confounders, an association with lead or DEHP was only observed. The present data shows that lead (Pb) or cadmium (Cd) or phthalates might independently contribute to decline in semen quality and induce DNA damage. Phthalates might influence reproductive hormone testosterone. These findings are significant in light of the fact that men are exposed to a volley of chemicals; however, due to the small sample size, our finding needs to be confirmed in a larger population.  相似文献   
43.
The present study attempts to analyze the biosorption trend of biosorbent Caulerpa fastigiata (macroalgae) biomass for removal of toxic heavy metal ion Pb (II) from solution as a function of initial metal ion concentration, pH, temperature, sorbent dosage, and biomass particle size. The sorption data fitted with various isotherm models and Freundlich model was the best one with correlation coefficient of 0.999. Kinetic study results revealed that the sorption data on Pb (II) with correlation coefficient of 0.999 can best be represented by pseudo-second-order. The biosorption capacity (q e ) of Pb (II) is 16.11?±?0.32 mg g?1 on C. fastigiata biomass. Thermodynamic studies showed that the process is exothermic (ΔH° negative). Free energy change (ΔG°) with negative sign reflected the feasibility and spontaneous nature of the process. The SEM studies showed Pb (II) biosorption on selective grains of the biosorbent. The FTIR spectra indicated bands corresponding to –OH, COO?, –CH, C?=?C, C?=?S, and –C–C– groups were involved in the biosorption process. The XRD pattern of the C. fastigiata was found to be mostly amorphous in nature.  相似文献   
44.
The use of sustainable, green and biodegradable natural wastes for Cr(VI) detoxification from the contaminated wastewater is considered as a challenging issue. The present research is aimed to assess the effectiveness of seven different natural biomaterials, such as jackfruit leaf, mango leaf, onion peel, garlic peel, bamboo leaf, acid treated rubber leaf and coconut shell powder, for Cr(VI) eradication from aqueous solution by biosorption process. Characterizations were conducted using SEM, BET and FTIR spectroscopy. The effects of operating parameters, viz., pH, initial Cr(VI) ion concentration, adsorbent dosages, contact time and temperature on metal removal efficiency, were studied. The biosorption mechanism was described by the pseudo-second-order model and Langmuir isotherm model. The biosorption process was exothermic, spontaneous and chemical (except garlic peel) in nature. The sequence of adsorption capacity was mango leaf > jackfruit leaf > acid treated rubber leaf > onion peel > bamboo leaf > garlic peel > coconut shell with maximum Langmuir adsorption capacity of 35.7 mg g?1 for mango leaf. The treated effluent can be reused. Desorption study suggested effective reuse of the adsorbents up to three cycles, and safe disposal method of the used adsorbents suggested biodegradability and sustainability of the process by reapplication of the spent adsorbent and ultimately leading towards zero wastages. The performances of the adsorbents were verified with wastewater from electroplating industry. The scale-up study reported for industrial applications. ANN modelling using multilayer perception with gradient descent (GD) and Levenberg-Marquart (LM) algorithm had been successfully used for prediction of Cr(VI) removal efficiency. The study explores the undiscovered potential of the natural waste materials for sustainable existence of small and medium sector industries, especially in the third world countries by protecting the environment by eco-innovation.  相似文献   
45.
This paper considers a two-echelon closed-loop supply chain consisting of a manufacturer and a remanufacturer at the upper echelon and a retailer at the lower echelon. The retailer faces a constant demand from customers, which is satisfied through recovered and new products received from the remanufacturer and the manufacturer, respectively. The manufacturer produces the product with finite rate, whereas the recovery of returned product is instantaneous at the remanufacturer. We develop three models to determine the optimal production-inventory policy of the players for minimizing the joint total cost of the system. In the first model, the retailer receives the product in batches from the manufacturer and the remanufacture simultaneously, whereas in the second and third models, the batches are received alternatively. In the third model, however, the procurement of raw material at the manufacturer is also considered. Numerical illustration is presented to examine the impact of certain key parameters.  相似文献   
46.
The environmentally sustainable disposal and recycling of ever increasing volumes of electronic waste has become a global waste management issue. The addition of up to 25% polymeric waste PCBs (printed circuit boards) as fillers in polypropylene (PP) composites was partially successful: while the tensile modulus, flexural strength and flexural modulus of composites were enhanced, the tensile and impact strengths were found to decrease. As a lowering of impact strength can significantly limit the application of PP based composites, it is necessary to incorporate impact modifying polymers such as rubbery particles in the mix. We report on a novel investigation on the simultaneous utilization of electronic and automotive rubber waste as fillers in PP composites. These composites were prepared by using 25 wt.% polymeric PCB powder, up to 9% of ethylene propylene rubber (EPR), and PP: balance. The influence of EPR on the structural, thermal, mechanical and rheological properties of PP/PCB/ EPR composites was investigated. While the addition of EPR caused the nucleation of the β crystalline phase of PP, the onset temperature for thermal degradation was found to decrease by 8%. The tensile modulus and strength decreased by 16% and 19%, respectively; and the elongation at break increased by ~71%. The impact strength showed a maximum increase of ~18% at 7 wt.%–9 wt.% EPR content. Various rheological properties were found to be well within the range of processing limits. This novel eco-friendly approach could help utilize significant amounts of polymeric electronic and automotive waste for fabricating valuable polymer composites.
  相似文献   
47.
Biodiesel provides a feasible solution to the twin crisis of energy security and environmental concerns prevalent today, and it can be extracted from conventional oil crops as well as microalgae. However, lipid productivity in case of microalgae is much higher and has several advantages as compared with crop plants, so it is a better feedstock for biodiesel. In case of Chlorella pyrenoidosa, the heterotrophic cultured cells were found to be better in terms of lipid production, and ultimately biodiesel production, but the bottleneck is that in this mode glucose is used to feed the cells, which amounts to almost 80% of the total cost of biodiesel production. The purpose of this study is to evaluate and highlight the feasibility of using the industrially cheap cane molasses as a carbon source in place of glucose for a large-scale, low-cost lipid production of Chlorella pyrenoidosa. When treated molasses was used as a carbon source instead of glucose, the biomass sharply increases from 0.89 to 1.22 g L–1. On the other hand, the total lipid content increases from 0.27 to 0.66 g g–1. The specific growth rate and yield was higher in treated molasses as compared with that in glucose-supplemented. A mathematical model was also developed based on logistic, Luedeking–Piret, and Luedeking-Piret-like equations. Model predictions were in satisfactory agreement with the measured data, and the mode of lipid production was growth-associated.  相似文献   
48.
Degradation of flubendiamide as affected by microbial population count in two Indian soils (red and alluvial) varying in physicochemical properties was studied under sterile and non-sterile conditions. Recovery of flubendiamide in soil was in the range of 94.7–95.9 % at 0.5 and 1.0 μg g?1, respectively. The DT50 of flubendiamide at the level of 10 μg g?1 in red soil under sterile and non-sterile conditions was found to be 140.3 and 93.7 days, respectively, and in alluvial soil under sterile and non-sterile condition was 181.1 and 158.4 days, respectively. Residues of flubendiamide dissipated faster in red soil (non-sterile followed by sterile) as compared to alluvial (non-sterile soil followed by sterile soil). A wide difference in half-life of red and alluvial soil under sterile and non-sterile conditions indicated that the variation in physicochemical properties of red and alluvial soil as well as the presence of microbes play a great role for degradation of flubendiamide. The results revealed that slower-degrading alluvial soil possessed microbes with degradative capacity. The degradation rate in this soil was significantly reduced by some of its physicochemical characteristics, despite sterile and non-sterile conditions, which was faster in red soil.  相似文献   
49.
The mortality rate of herpetofauna due to road accidents in one of the busiest tarmacked metalled roads of Durgapur, an industrial town of West Bengal, India was studied. Road survey for 27 days covering a total distance of 94.5 km was conducted. Within this span of time and the total stretch of road, 354 amphibians belonging to 6 species and 133 reptiles belonging to 11 species were observed to be killed in road-accidents. Among amphibians, Duttaphrynus melanostictus and amongst the reptiles Hemidactylus spp. were killed in highest numbers. The stretch of road under survey passed through different habitat patches like’s agricultural land, human habitation, dumping area, fragmented forest and wetland. On an average, 18 herpetofauna was noted to be killed daily. It was difficult to identify the species as the key characters were missing in the remains in a few cases of road casualties. High road mortality of herpetofauna would surely affect the balance of adjoining ecosystems as well as may be crucial for the local herpetofaunal population attributes.  相似文献   
50.
Environmental Science and Pollution Research - Phytoremediation coupled with crop rotation (PCC) is a feasible strategy for remediation of contaminated soil without interrupting crop production....  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