全文获取类型
收费全文 | 7085篇 |
免费 | 838篇 |
国内免费 | 2027篇 |
专业分类
安全科学 | 1939篇 |
废物处理 | 550篇 |
环保管理 | 810篇 |
综合类 | 4039篇 |
基础理论 | 704篇 |
环境理论 | 4篇 |
污染及防治 | 1168篇 |
评价与监测 | 447篇 |
社会与环境 | 174篇 |
灾害及防治 | 115篇 |
出版年
2024年 | 22篇 |
2023年 | 116篇 |
2022年 | 212篇 |
2021年 | 300篇 |
2020年 | 307篇 |
2019年 | 283篇 |
2018年 | 278篇 |
2017年 | 389篇 |
2016年 | 423篇 |
2015年 | 477篇 |
2014年 | 462篇 |
2013年 | 616篇 |
2012年 | 688篇 |
2011年 | 645篇 |
2010年 | 472篇 |
2009年 | 470篇 |
2008年 | 311篇 |
2007年 | 491篇 |
2006年 | 497篇 |
2005年 | 336篇 |
2004年 | 274篇 |
2003年 | 289篇 |
2002年 | 264篇 |
2001年 | 227篇 |
2000年 | 208篇 |
1999年 | 160篇 |
1998年 | 134篇 |
1997年 | 126篇 |
1996年 | 112篇 |
1995年 | 94篇 |
1994年 | 74篇 |
1993年 | 53篇 |
1992年 | 35篇 |
1991年 | 28篇 |
1990年 | 27篇 |
1989年 | 7篇 |
1988年 | 9篇 |
1987年 | 5篇 |
1986年 | 6篇 |
1985年 | 5篇 |
1983年 | 3篇 |
1980年 | 3篇 |
1979年 | 2篇 |
1977年 | 1篇 |
1975年 | 1篇 |
1974年 | 1篇 |
1973年 | 1篇 |
1972年 | 2篇 |
1971年 | 1篇 |
1970年 | 1篇 |
排序方式: 共有9950条查询结果,搜索用时 15 毫秒
81.
Jorge Rickards 《Journal of environmental radioactivity》2010,101(5):333-337
The functioning of radon diffusion chambers was studied using the Monte Carlo code RAMMX developed here. The alpha particles from radon are assumed randomly produced in the volume of the cylinder, and those from the progeny are assumed to originate randomly at the cylindrical surface. The energy spectrum, the distribution of incident angles, and the distribution of path lengths of the alpha particles on the detector were obtained. These quantities vary depending on input parameters such as initial alpha particle energy, radius and depth of the diffusion chamber, detector size and atmospheric pressure. The calculated energy spectrum for both 222Rn and 220Rn was compared with experiment, permitting the identification of each peak and its origin, and a better understanding of radon monitoring. Three aspects not considered in previous calculations are progeny alphas coming from surfaces of the monitor, taking into account the atmospheric pressure, and including the isotope 220Rn. 相似文献
82.
Benzene is a representative member of volatile organic compounds and has been widely used as an industrial solvent. Groundwater contamination of benzene may pose risks to human health and ecosystems. Detection of benzene in the groundwater using chemical analysis is expensive and time consuming. In addition, biological responses to environmental exposures are uninformative using such analysis. Therefore, the aim of this study was to employ a microorganism, Euglena gracilis (E. gracilis) as a putative model to monitor the contamination of benzene in groundwater. To this end, we examined the wild type of E. gracilis Z and its mutant form, SMZ in their growth rate, morphology, chlorophyll content, formation of reactive oxygen species (ROS) and DNA damage in response to benzene exposure. The results showed that benzene inhibited cell growth in a dose response manner up to 48 h of exposure. SMZ showed a greater sensitivity compared to Z in response to benzene exposure. The difference was more evident at lower concentrations of benzene (0.005–5 μM) where growth inhibition occurred in SMZ but not in Z cells. We found that benzene induced morphological changes, formation of lipofuscin, and decreased chlorophyll content in Z strain in a dose response manner. No significant differences were found between the two strains in ROS formation and DNA damage by benzene at concentrations affecting cell growth. Based on these results, we conclude that E. gracilis cells were sensitive to benzene-induced toxicities for certain endpoints such as cell growth rate, morphological change, depletion of chlorophyll. Therefore, it is a potentially suitable model for monitoring the contamination of benzene and its effects in the groundwater. 相似文献
83.
生物填料地下渗滤系统对生活污水的脱氮 总被引:1,自引:0,他引:1
将草甸棕壤、炉渣和活性污泥等基质按体积比13∶6∶1配制生物填料,研究了生物填料地下渗滤系统(subsurface wastewater infiltration system,SWIS)在不同的水力负荷和污染负荷条件下对校园生活污水的脱氮效果。场地实验结果表明,当BOD5负荷为12.0 g BOD5/(m2·d),表面水力负荷为0.04-0.10 m3/(m2·d)时,SWIS对NH+4-N和TN的平均去除率分别为92.4%和82.0%。当水力负荷为0.08 m3/(m2·d),BOD5负荷9.3-16.8 g BOD5/(m2·d)时,SWIS对NH+4-N和TN的平均去除率为92.7%和81.2%。SWIS中氧化还原电位(oxygen reduction potential,ORP)随进水水力负荷和BOD5负荷的增加而降低,脱氮效率下降。综合出水水质和处理效率,适宜的水力负荷和污染负荷分别为0.065 m3/(m2·d)和12.0 g BOD5/(m2·d)。在此条件下,SWIS的启动周期为25-30 d。出水水质均优于《城市污水再生利用-景观环境用水水质》(GB/T18921-2002)标准,且处理效果稳定,抗负荷冲击能力强。 相似文献
84.
The widespread occurrence of pesticide residues in different agricultural and food commodities has raised concern among the environmentalists and food chemists. In order to keep a proper track of these materials, studies on their decay profiles in the various segments of ecosystem under varying environmental conditions are needed. In view of this, the metabolites of quinalphos in water and soil under controlled conditions and in plants, namely tomato and radish in field conditions have been analysed and possible pathways suggested. In order to follow the decay of the pesticide, an HPLC procedure has been developed. Studies conducted in water at different temperatures, pH and organic content reveal that the persistence of the pesticide decreases with the increase in all the three variables. In the three different types of soils studied, the effect of pH is more or less apparent on a similar line. On an average a faster decay is observed in the case of plants than in water and soil. The decay profiles in all these cases follow first order kinetics. The metabolites were identified by GC-MS. The investigations reflect that degradation occurs through hydrolysis, S-oxidation, dealkylation and thiono-thiol rearrangement. The pathways seem to be complex and different metabolites were observed with the change in the matrix. Quinalphos oxon, O-ethyl-O-quinoxalin-2-yl phosphoric acid, 2-hydroxy quinoxaline and quinoxaline-2-thiol were observed in all the matrices. Results further indicate that the metabolites, 2-hydroxy quinoxaline and oxon, which are more toxic than parent compound, persist for a longer time. 相似文献
85.
A study has been made of the effect a reactive barrier made of pine (softwood) or oak (hardwood) wood intercalated in a sandy soil column has on the retention of linuron, alachlor and metalaxyl (pesticides with contrasting physicochemical characteristics). The leaching of pesticides has been carried out under a saturated flow regime and breakthrough curves (BTCs) have been obtained at flow rates of 1 mL min−1 (all pesticides) and 3 mL min−1 (linuron). The cumulative curves in the unmodified soil indicate a leaching of pesticides >80% of the total amount of compound added. After barrier intercalation, linuron leaching decreases significantly and a modification of the leaching kinetics of alachlor and metalaxyl has been observed. The theoretical R factors increased ∼2.6-3.3, 1.2-1.6-fold, and 1.4-1.7-fold and the concentration of the maximum peak decreased ∼6-12-fold, 2-4-fold and 1.2-2-fold for linuron, alachlor and metalaxyl, respectively. When considering the three pesticides, significant correlations have been found between the theoretical retardation factor (R) and the pore volume corresponding to the maximum peaks of the BTCs (r = 0.77; p < 0.05) or the total volume leached (r = −0.78; p < 0.05). The results reveal the efficacy of reactive wood barriers to decrease the leaching of pesticides from point sources of pollution depends on the type of wood, the hydrophobicity of the pesticide and the adopted water flow rate. Pine was more effective than oak in decreasing the leaching of hydrophobic pesticide linuron or in decreasing the maximum peak concentration of the less hydrophobic pesticides in soils. Efficacy of these wood barriers was limited for the least hydrophobic pesticide metalaxyl. 相似文献
86.
87.
88.
The bromination of five selected pharmaceuticals (metoprolol, naproxen, amoxicillin, phenacetin, and hydrochlorothiazide) was studied with these compounds individually dissolved in ultra-pure water. The apparent rate constants for the bromination reaction were determined as a function of the pH, obtaining the sequence amoxicillin > naproxen ? hydrochlorothiazide ≈ phenacetin ≈ metoprolol. A kinetic mechanism specifying the dissociation reactions and the species formed for each compound according to its pKa value and the pH allowed the intrinsic rate constants to be determined for each elementary reaction. There was fairly good agreement between the experimental and calculated values of the apparent rate constants, confirming the goodness of the proposed reaction mechanism.In a second stage, the bromination of the selected pharmaceuticals simultaneously dissolved in three water matrices (a groundwater, a surface water from a public reservoir, and a secondary effluent from a WWTP) was investigated. The pharmaceutical elimination trend agreed with the previously determined rate constants. The influence of the main operating conditions (pH, initial bromine dose, and characteristics of the water matrix) on the degradation of the pharmaceuticals was established. An elimination concentration profile for each pharmaceutical in the water matrices was proposed based on the use of the previously evaluated apparent rate constants, and the theoretical results agreed satisfactorily with experiment. Finally, chlorination experiments performed in the presence of bromide showed that low bromide concentrations slightly accelerate the oxidation of the selected pharmaceuticals during chlorine disinfection. 相似文献
89.
采用浸渍-热分解法制备了含IrOx-TiO2中间层的IrO2-SnO2电极,得到的电极具有较高的析氯电催化活性和较强的稳定性,并通过电化学氧化法对Na2SO3海水脱硫模拟液进行处理,考察了电流密度、温度、pH值和电解时间等电解工艺参数对Na2SO3去除率和化学需氧量COD的影响。结果表明,在电流密度为200 mA/cm^2,pH值为3.5,电解440 mg/L的Na2SO3海水脱硫模拟液,15 min时Na2SO3去除率可达96.5%,COD去除率可达82.6%。 相似文献
90.