全文获取类型
收费全文 | 1273篇 |
免费 | 339篇 |
国内免费 | 327篇 |
专业分类
安全科学 | 103篇 |
废物处理 | 27篇 |
环保管理 | 81篇 |
综合类 | 651篇 |
基础理论 | 819篇 |
污染及防治 | 163篇 |
评价与监测 | 64篇 |
社会与环境 | 12篇 |
灾害及防治 | 19篇 |
出版年
2024年 | 1篇 |
2023年 | 15篇 |
2022年 | 29篇 |
2021年 | 30篇 |
2020年 | 28篇 |
2019年 | 36篇 |
2018年 | 112篇 |
2017年 | 86篇 |
2016年 | 96篇 |
2015年 | 103篇 |
2014年 | 127篇 |
2013年 | 158篇 |
2012年 | 130篇 |
2011年 | 136篇 |
2010年 | 107篇 |
2009年 | 88篇 |
2008年 | 73篇 |
2007年 | 63篇 |
2006年 | 50篇 |
2005年 | 47篇 |
2004年 | 47篇 |
2003年 | 43篇 |
2002年 | 32篇 |
2001年 | 33篇 |
2000年 | 61篇 |
1999年 | 27篇 |
1998年 | 20篇 |
1997年 | 19篇 |
1996年 | 21篇 |
1995年 | 18篇 |
1994年 | 16篇 |
1993年 | 16篇 |
1992年 | 19篇 |
1991年 | 6篇 |
1990年 | 3篇 |
1989年 | 9篇 |
1988年 | 6篇 |
1987年 | 5篇 |
1985年 | 3篇 |
1984年 | 3篇 |
1983年 | 6篇 |
1982年 | 3篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1978年 | 2篇 |
1975年 | 1篇 |
1974年 | 1篇 |
1971年 | 1篇 |
排序方式: 共有1939条查询结果,搜索用时 404 毫秒
701.
提出化工园区的危险量并探讨其含义。选择基础危险量计算模型及安全评估指标,建立化工园区企业基础危险量计算模型。通过对影响化工园区企业安全的因素进行筛选,建立企业危险量影响因素体系。在此基础上,运用改进G1法和模糊综合评价法确定各因素的权重和隶属度,对化工园区企业基础危险量模型进行改进,提出化工园区企业危险量和园区总体危险量的计算模型。实现了化工园区危险程度的量化,进而辅助化工园区的安全管理和安全规划。 相似文献
702.
基于G_1法的飞行疲劳综合评价指标体系研究 总被引:2,自引:1,他引:1
为综合控制并评价飞行疲劳风险,通过对疲劳影响因素的深入分析,运用层次分析法(AHP)确定疲劳风险评价指标,依据G1法编制专家调查问卷,采用专家独立调查方法对指标进行判断,根据G1法确定各指标权重,建立飞行疲劳综合评价指标体系,实现对疲劳风险的量化综合评价。结果表明:运用G1法能有效地综合利用影响疲劳的各种信息评价飞行员的疲劳状况,该指标体系与现有控制飞行疲劳风险的影响因素吻合较好,可以作为进一步实现疲劳风险量化的基础。 相似文献
703.
1-((cyano-1-methylethyl) azo) formamide (CABN) is an azo compound that exhibits high thermal sensitivity and self-reactivity. Because of incorrect operation, incompatible substances and other dangerous conditions, thermal explosion accidents may occur during the manufacturing, storage, and transportation of CABN. The pyrolysis characteristics of CABN and its mixture for various heating rates were assessed using differential scanning calorimetry. The results showed that incompatible substances increased the risk of CABN. Moreover, the thermal runaway of CABN under an adiabatic condition was studied using an adiabatic rate calorimeter to obtain the parameters under adiabatic condition. Based on the experimental data, the kinetic parameters of CABN and its mixtures were obtained. In addition, a thermal decomposition kinetic model of CABN was created using Thermal Safety Series. All experiments have shown that the conditions and parameters of CABN must be strictly controlled. 相似文献
704.
Engineered silica nanoparticles (SiO2-NPs) find widespread application and may lead to exposure of humans and the environment. Here we compare the effects of SiO2-NPs and SiO2-NPs doped with silver (SiO2-Ag-NPs) on survival and cellular function of human liver cells (Huh7) and Pimephales promelas (fathead minnow) fibroblast cells (FMH). In Huh7 cells we investigate effects on the endoplasmatic reticulum (ER), including ER stress, and interactions of nanoparticles (NPs) with metabolizing enzymes and efflux transporters. The NPs formed agglomerates/aggregates in cell culture media as revealed by SEM and TEM. SiO2 and SiO2-1% Ag-NPs were taken up into cells as demonstrated by agglomerates occurring in vesicular-like structures or freely dispersed in the cytosol. Cytotoxicity was more pronounced in Huh7 than in FMH cells, and increased with silver content in silver-doped NPs. Dissolved silver was the most significant factor for cytotoxicity. At toxic and non-cytotoxic concentrations SiO2-NPs and SiO2-1% Ag-NPs induced perturbations in the function of ER. In Huh7 cells NPs induced the unfolded protein response (UPR), or ER stress response, as demonstrated in induced expression of BiP and splicing of XBP1 mRNA, two selective markers of ER stress. Additionally, SiO2-1% Ag-NPs and AgNO3 induced reactive oxygen species. Pre-treatment of Huh7 cells with SiO2-1% Ag-NPs followed by exposure to the inducer benzo(a)pyrene caused a significant reduced induction of CYP1A activity. NPs did not alter the activity of ABC transporters. These data demonstrate for the first time that SiO2-NPs and SiO2-1% Ag-NPs result in perturbations of the ER leading to the ER stress response. This represents a novel and significant cellular signalling pathway contributing to the cytotoxicity of NPs. 相似文献
705.
706.
This article critically examines the nature and quality of governance in community representation and civil society engagement in the context of trans-national large-scale mining, drawing on experiences in the Anosy Region of south-east Madagascar. An exploration of functional relationships between government, mining business and civil society stakeholders reveals an equivocal legitimacy of certain civil society representatives, created by state manipulation, which contributes to community disempowerment. The appointment of local government officials, rather than election, creates a hierarchy of upward dependencies and a culture where the majority of officials express similar views and political alliances. As a consequence, community resistance is suppressed. 相似文献
707.
García-Esquinas E Pérez-Gómez B Fernández MA Pérez-Meixeira AM Gil E de Paz C Iriso A Sanz JC Astray J Cisneros M de Santos A Asensio A García-Sagredo JM García JF Vioque J Pollán M López-Abente G González MJ Martínez M Bohigas PA Pastor R Aragonés N 《Chemosphere》2011,85(2):268-276
Background
Although breastfeeding is the ideal way of nurturing infants, it can be a source of exposure to toxicants. This study reports the concentration of Hg, Pb and Cd in breast milk from a sample of women drawn from the general population of the Madrid Region, and explores the association between metal levels and socio-demographic factors, lifestyle habits, diet and environmental exposures, including tobacco smoke, exposure at home and occupational exposures.Methods
Breast milk was obtained from 100 women (20 mL) at around the third week postpartum. Pb, Cd and Hg levels were determined using Atomic Absorption Spectrometry. Metal levels were log-transformed due to non-normal distribution. Their association with the variables collected by questionnaire was assessed using linear regression models. Separate models were fitted for Hg, Pb and Cd, using univariate linear regression in a first step. Secondly, multivariate linear regression models were adjusted introducing potential confounders specific for each metal. Finally, a test for trend was performed in order to evaluate possible dose-response relationships between metal levels and changes in variables categories.Results
Geometric mean Hg, Pb and Cd content in milk were 0.53 μg L−1, 15.56 μg L−1, and 1.31 μg L−1, respectively. Decreases in Hg levels in older women and in those with a previous history of pregnancies and lactations suggested clearance of this metal over lifetime, though differences were not statistically significant, probably due to limited sample size. Lead concentrations increased with greater exposure to motor vehicle traffic and higher potato consumption. Increased Cd levels were associated with type of lactation and tended to increase with tobacco smoking.Conclusions
Surveillance for the presence of heavy metals in human milk is needed. Smoking and dietary habits are the main factors linked to heavy metal levels in breast milk. Our results reinforce the need to strengthen national food safety programs and to further promote avoidance of unhealthy behaviors such as smoking during pregnancy. 相似文献708.
巯基功能化13X分子筛对Pb(Ⅱ)的吸附 总被引:1,自引:0,他引:1
用3-巯丙基三甲氧基硅烷(MPTMS)对13X分子筛表面进行修饰,采用XRD和FT—JR测试方法对功能化前后的分子筛结构进行表征,结果表明,功能化后分子筛在保持原有结构同时表面还接枝了对Ph^2+离子有吸附能力的巯基基团。吸附实验表明,巯基功能化分子筛对水中Ph^2+离子比原分子筛具有更强的吸附去除效果,饱和吸附容量和去除率提高近一倍。SH-13X对Ph^2+离子的等温吸附符合Langmuir模型,最大吸附容量为47.01mg/g,吸附强度b为2.26。动力学分析表明SH-13X对Ph^2+离子的吸附过程更符合准二级动力学模型,而且粒内扩散不是该吸附过程的主要吸附机制。溶液中的Ph“与嫁接在分子筛表面及孔口位置的-SH功能团形成配位络合物而去除。 相似文献
709.
710.
Varank G Demir A Yetilmezsoy K Bilgili MS Top S Sekman E 《Waste management (New York, N.Y.)》2011,31(11):2263-2274
One-dimensional (1D) advection–dispersion transport modeling was conducted as a conceptual approach for the estimation of the transport parameters of fourteen different phenolic compounds (phenol, 2-CP, 2-MP, 3-MP, 4-MP, 2-NP, 4-NP, 2,4-DNP, 2,4-DCP, 2,6-DCP, 2,4,5-TCP, 2,4,6-TCP, 2,3,4,6-TeCP, PCP) and three different inorganic contaminants (Cu, Zn, Fe) migrating downward through the several liner systems. Four identical pilot-scale landfill reactors (0.25 m3) with different composite liners (R1: 0.10 + 0.10 m of compacted clay liner (CCL), Le = 0.20 m, ke = 1 × 10−8 m/s, R2: 0.002-m-thick damaged high-density polyethylene (HDPE) geomembrane overlying 0.10 + 0.10 m of CCL, Le = 0.20 m, ke = 1 × 10−8 m/s, R3: 0.002-m-thick damaged HDPE geomembrane overlying a 0.02-m-thick bentonite layer encapsulated between 0.10 + 0.10 m CCL, Le = 0.22 m, ke = 1 × 10−8 m/s, R4: 0.002-m-thick damaged HDPE geomembrane overlying a 0.02-m-thick zeolite layer encapsulated between 0.10 + 0.10 m CCL, Le = 0.22 m, ke = 4.24 × 10−7 m/s) were simultaneously run for a period of about 540 days to investigate the nature of diffusive and advective transport of the selected organic and inorganic contaminants. The results of 1D transport model showed that the highest molecular diffusion coefficients, ranging from 4.77 × 10−10 to 10.67 × 10−10 m2/s, were estimated for phenol (R4), 2-MP (R1), 2,4-DNP (R2), 2,4-DCP (R1), 2,6-DCP (R2), 2,4,5-TCP (R2) and 2,3,4,6-TeCP (R1). For all reactors, dispersion coefficients of Cu, ranging from 3.47 × 10−6 m2/s to 5.37 × 10−2 m2/s, was determined to be higher than others obtained for Zn and Fe. Average molecular diffusion coefficients of phenolic compounds were estimated to be about 5.64 × 10−10 m2/s, 5.37 × 10−10 m2/s, 2.69 × 10−10 m2/s and 3.29 × 10−10 m2/s for R1, R2, R3 and R4 systems, respectively. The findings of this study clearly indicated that about 35–50% of transport of phenolic compounds to the groundwater is believed to be prevented with the use of zeolite and bentonite materials in landfill liner systems. 相似文献