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151.
成分复杂的垃圾渗滤液经处理后,研究其中残留的极低浓度的酚类环境内分泌干扰物的雌激素效应及其对生态环境的毒性作用具有非常重要的实际价值.本文选择对雌激素敏感的MCF-7人类乳腺癌细胞进行体外培养,将老龄渗滤液原液、经过内部微电解(IME)和内部微电解结合芬顿试剂(IME-Fenton)处理后的渗滤液酚类提取液稀释10~107倍,采用MTT法测定MCF-7细胞的增殖和细胞划痕损伤实验评价渗滤液中酚类物质的雌激素效应,并探讨了活性炭在反应中对酚类物质的去除效果.结果表明,渗滤液中酚类提取物对MCF-7细胞增殖在浸染72 h后达到最大;与渗滤液原液相比,渗滤液经IME和IME-Fenton处理后,最大增殖效应分别下降了85%和110%,酚类提取物减缓了MCF-7细胞的迁移速度;活性炭对渗滤液中酚的吸附主要发生在反应前30 min,渗滤液经活性炭吸附后的酚类提取物稀释10~107倍仍表现出细胞毒性.渗滤液经IME-Fenton处理后降低了酚类物质进入环境引起的危害,MCF-7细胞增殖和细胞划痕也为检测浓度低至10-15g·L-1的酚类雌激素提供新方法. 相似文献
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153.
Evaluation of Satellite‐Derived Rainfall Data for Multiple Physio‐Climatic Regions in the Santiago River Basin,Mexico
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J.R. Ávila‐Carrasco H.E. Júnez‐Ferreira P.H. Gowda J.L. Steiner D.N. Moriasi P.J. Starks J. Gonzalez A.A. Villalobos C. Bautista‐Capetillo 《Journal of the American Water Resources Association》2018,54(5):1068-1086
Assessment of water resources requires reliable rainfall data, and rain gauge networks may not provide adequate spatial representation due to limited point measurements. The Tropical Rainfall Measuring Mission (TRMM) provides rainfall data at global scale, and has been used with good results. However, TRMM data are an indirect measurement of rainfall, and therefore must be validated for its proper use. In this work, a validation scheme was designed and implemented to compare the TRMM Version 7 (V7) monthly rainfall product at different time frames with data measured in two hydrologic subregions of the Santiago River Basin (SRB) in Mexico: Río Alto Santiago and Río Bajo Santiago (RBS). Additionally, three physio‐climatic regions provide an assessment of the interplay of topography, distance from coastal regions, and seasonal weather patterns on the correspondence between both datasets. The TRMM V7 rainfall product exhibited good agreement with the rain gauge data particularly for the RBS and for the whole SRB during wettest summer and autumn seasons. However, strong regional dependence was observed due to differences in climate and topography. Overall, in spite of some noted underestimations, the monthly TRMM V7 rainfall product was found to provide useful information that can be used to complement limited monitoring as is the case of RBS. An improved combined rainfall product could be generated and thus gaining the most benefits from both data sources. 相似文献
154.
在珊溪水库藻类暴发期间应急监测数据的基础上,建立pH值、高锰酸盐指数、总氮、总磷、叶绿素a数据矩阵。运用MATLAB R2015b GUI可视化界面模块,将应急监测数据样本空间分为训练样本、验证样本、测试样本,建立珊溪水库BP神经网络模型,预测了珊溪水库藻类暴发期间叶绿素a浓度。BP神经网络建模结果显示:输出数据与实测数据相关系数0.978,平均相对误差-0.19%,标准方差18.54%,模型稳定性较好,叶绿素a预测结果符合预期。BP神经网络预测模型为珊溪水库饮用水水源地环境保护提供了科学依据。 相似文献
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156.
Surface air concentrations of 7Be at a number of stations in Oceania show a distinct annual cycle. We apply a sinusoidal model to describe this cycle. The results show that peak 7Be concentrations in surface air occur during early spring at tropical latitudes and during mid-to-late summer at middle latitudes. Comparison with available 90Sr surface air data for the southern hemisphere indicates that stratosphere-to-troposphere exchange is an active atmospheric process controlling the 7Be annual cycle throughout the Oceania region. Vertical transport of air within the troposphere also seems to influence the observed annual cycle. Seasonality in rainfall is not thought to control the annual cyclic behaviour of 7Be in surface air. 相似文献
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158.
Fuel and leasable minerals mined in the United States have historically been subject to federal royalties while locatable minerals have not. In recent years there have been multiple attempts to alter this policy and subject locatable minerals to federal royalties as well; most recently the preliminary 2012 Obama budget included a gross royalty on hard-rock mining on public lands. This paper analyzes the issue of imposing such federal royalties from both a legal and economic perspective. From a legal perspective, it is argued that the state of western property rights precludes royalties on currently extant claims so revenues from a royalty would not be realized for many years. From an economic perspective, it is argued that the effect on revenue would be smaller than one might anticipate due to such a royalty crowding out state levies or encouraging vertical disintegration on the part of mining firms to avoid much of the burden of the royalty. 相似文献
159.
The formulation of most pesticides is proprietary and individual components are therefore not generally known. In a preliminary study, we identified six compounds that are often present in pesticides, of which 4-nonylphenyl-polyethylene glycol(NP-40) was found to be the most toxic. In this study, we investigated the toxicity of NP-40 and underlying mechanism in neuronal SK-N-SH cells. Exposure to NP 40 at concentrations higher than60 μmol/L for 24 hr decreased cell viability. The cytotoxicity of NP-40 was time-and concentration-dependent. Nuclear fragmentation and chromatin condensation were apparent starting at 50 μmol/L NP-40, and increased at higher concentrations. The expression of apoptotic factors including p53 and B-cell lymphoma(Bcl)-2-associated X protein was upregulated, while that of the anti-apoptotic marker Bcl-2 was downregulated at 80 μmol/L NP-40. Cytochrome c release was observed from 80 to 100 μmol/L by confocal microscopy. Caspase-9 and-3/7 activities increased according to concentration, and fluorescence-activated cell sorting analysis showed that apoptosis was induced at50 μmol/L and was increased at 80 μmol/L. Our findings indicate that NP-40 stimulates the mitochondrial-mediated apoptosis pathway and reactive oxygen species production in a concentration-dependent manner, and suggest that antioxidant administration may be an effective treatment for patients with acute NP-40 poisoning. 相似文献
160.
目的开展飞机用7B04铝合金缝隙腐蚀仿真研究,理解缝隙腐蚀机理,找出影响缝隙腐蚀的关键因素。方法分析缝隙腐蚀类型,开展缝隙腐蚀试验,建立缝隙腐蚀数学模型,选择合适的边界条件,利用有限元法进行仿真计算。结果缝隙内pH值分布计算结果与试验测量值一致,缝隙口与外部液体/大气连接时,缝隙内溶液分别呈酸性或碱性。缝隙口溶液电势较低,缝隙口附近的铝合金腐蚀较快,含Al腐蚀产物多集中在缝隙口附近。缝隙宽度在0.1~0.3 mm范围内变化不影响铝合金腐蚀速率;缝隙深度增加,缝隙口与底部溶液电势差增大,铝合金腐蚀面积增大,但铝合金最大腐蚀电流密度不变。电位升高,缝隙内铝合金的腐蚀加剧,电位提高10 m V,腐蚀24 h后缝隙内铝合金界面的腐蚀电流密度增加59倍,Al(OH)_2Cl的最大浓度为自然电位下的30倍。结论缝隙腐蚀主要受缝隙外部阴极还原反应影响,电位对铝合金缝隙腐蚀的影响最大,飞机结构中应避免高电位材料同铝合金直接接触。 相似文献