全文获取类型
收费全文 | 2052篇 |
免费 | 362篇 |
国内免费 | 1712篇 |
专业分类
安全科学 | 180篇 |
废物处理 | 253篇 |
环保管理 | 126篇 |
综合类 | 2281篇 |
基础理论 | 513篇 |
污染及防治 | 716篇 |
评价与监测 | 36篇 |
社会与环境 | 19篇 |
灾害及防治 | 2篇 |
出版年
2024年 | 6篇 |
2023年 | 36篇 |
2022年 | 89篇 |
2021年 | 124篇 |
2020年 | 96篇 |
2019年 | 135篇 |
2018年 | 124篇 |
2017年 | 140篇 |
2016年 | 161篇 |
2015年 | 232篇 |
2014年 | 204篇 |
2013年 | 414篇 |
2012年 | 380篇 |
2011年 | 271篇 |
2010年 | 225篇 |
2009年 | 234篇 |
2008年 | 140篇 |
2007年 | 189篇 |
2006年 | 196篇 |
2005年 | 105篇 |
2004年 | 93篇 |
2003年 | 98篇 |
2002年 | 71篇 |
2001年 | 64篇 |
2000年 | 45篇 |
1999年 | 42篇 |
1998年 | 42篇 |
1997年 | 33篇 |
1996年 | 36篇 |
1995年 | 19篇 |
1994年 | 16篇 |
1993年 | 17篇 |
1992年 | 13篇 |
1991年 | 8篇 |
1990年 | 7篇 |
1989年 | 8篇 |
1988年 | 4篇 |
1987年 | 3篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1974年 | 2篇 |
1971年 | 1篇 |
1969年 | 1篇 |
排序方式: 共有4126条查询结果,搜索用时 15 毫秒
901.
几种粘土矿物和粘土对溶液中磷的吸附效果 总被引:2,自引:0,他引:2
通过磷等温吸附与饱和吸附后释放试验,研究了高岭土、蒙脱土、凹凸棒土、蛭石和沸石对溶液中磷的吸附效果及其影响因素。结果表明,蛭石磷理论饱和吸附量最大,为3473mg·kg-1,其他依次为凹凸棒土、黄褐土、蒙脱土、下蜀黄土和沸石,高岭土磷理论饱和吸附量最低,为554mg·kg-1。影响粘土矿物和粘土磷理论饱和吸附量的主要因素是钙含量和胶体氧化铁及氧化铝的含量,pH值、阳离子交换量和比表面对磷理论饱和吸附量影响不大,粘土矿物和粘土吸附磷的机制主要为化学吸附。粘土矿物和粘土磷饱和吸附后释放试验表明其磷释放量很低。 相似文献
902.
Christel Faes Marc Aerts Helena Geys Geert Molenberghs Lieven Declerck 《Environmental and Ecological Statistics》2004,11(3):305-322
Developmental toxicity studies are widely used to investigate the potential risk of environmental hazards. In dose–response experiments, subjects are randomly allocated to groups receiving various dose levels. Tests for trend are then often applied to assess possible dose effects. Recent techniques for risk assessment in this area are based on fitting dose–response models. The complexity of such studies implies a number of non-trivial challenges for model development and the construction of dose-related trend tests, including the hierarchical structure of the data, litter effects inducing extra variation, the functional form of the dose–response curve, the adverse event at dam or at fetus level, the inference paradigm, etc. The purpose of this paper is to propose a Bayesian trend test based on a non-linear power model for the dose effect and using an appropriate model for clustered binary data. Our work is motivated by the analysis of developmental toxicity studies, in which the offspring of exposed and control rodents are examined for defects. Simulations show the performance of the method over a number of samples generated under typical experimental conditions. 相似文献
903.
表面活性剂对柴油在土壤中吸附的影响 总被引:2,自引:0,他引:2
通过静态吸附实验,研究土壤对十二烷基苯磺酸钠(LAS)和十六烷基三甲基溴化铵(CTAB)的吸附行为,探讨表面活性剂对柴油吸附的影响.结果表明,土壤对LAS和CTAB的吸附等温线均为非线性,其吸附能力的大小顺序为:轻壤土>轻粘土>中壤土>砂壤土>重壤土>紧砂土.同一土壤中,CTAB的吸附量大于LAS的吸附量.LAS和CTAB均利于柴油在土壤表面的解吸,且LAS的解吸效果更好.柴油的吸附量随LAS浓度的升高而降低.当CTAB的浓度小于临界胶束浓度CMC时,吸附量随CTAB浓度的升高而升高,当CTAB的浓度等于或大于临界胶束浓度(CMC)时,吸附量随CTAB浓度的升高而降低. 相似文献
904.
生物吸附剂-海黍子吸附镍 总被引:4,自引:0,他引:4
采用生物吸附剂-海黍子对重金属镍离子进行吸附,做了动力学实验,得到了海黍子吸附镍的动力学方程。研究了溶液的pH值,初始Ni^2 浓度等因素对Ni^2 的吸附特性的影响,得到最佳pH值4~6及最大吸附量0.8283mmo1/g,并用Langmuir和Freundlich方程对吸附等温线进行了拟合,用Langmuir方程拟合相关系数R^2达0.999以上。 相似文献
905.
麦饭石对Pb2+离子吸附的动力学研究 总被引:12,自引:0,他引:12
本文研究了水溶液中麦饭石对Pb^2+离子去除的反应动力学,考察了MFS粒度、溶液PH值和铅离子的初始浓度对吸附反应的影响。结果表明,MFS对Pb^2离子具有较强的吸附性能,PH值是影响吸附的主要因素,Pb^2+离子吸附的最初速率与浓度符合一级反应动力学;吸附过程符合Langmuir吸附等温式;离子交换和表面络合反应是主要吸附形式。 相似文献
906.
907.
Binary matrices originating from presence/absence data on species (rows) distributed over sites (columns) have been a subject of much controversy in ecological biogeography. Under the null hypothesis that every matrix is equally likely, the distributions of some test statistics measuring co-occurrences between species are sought, conditional on the row and column totals being fixed at the values observed for some particular matrix. Many ad hoc methods have been proposed in the literature, but at least some of them do not provide uniform random samples of matrices. In particular, some swap algorithms have not accounted for the number of neighbors each matrix has in the universe of matrices with a set of fixed row and column sums. We provide a Monte-Carlo method using random walks on graphs that gives correct estimates for the distributions of statistics. We exemplify its use with one statistic. 相似文献
908.
Gerda Claeskens Marc Aerts Geert Molenberghs Louise Ryan 《Environmental and Ecological Statistics》2002,9(4):357-377
We investigate several methods commonly used to obtain a benchmark dose and show that those based on full likelihood or profile likelihood methods might have severe shortcomings. We propose two new profile likelihood-based approaches which overcome these problems. Another contribution is the extension of the benchmark dose determination to non full likelihood models, such as quasi-likelihood, generalized estimating equations, which are widely used in settings such as developmental toxicity where clustered data are encountered. This widening of the scope of application is possible by the use of (robust) score statistics. Benchmark dose methods are applied to a data set from a developmental toxicity study. 相似文献
909.
研究了茜素络合剂-微分吸附计时电位法(AC-ASV)测定土壤溶液中铝形态的最佳条件,着重探讨了共存离子,特别是土壤溶液中的无机离子和有机阴离子对测定铝的影响,建立了测定土壤溶液中铝形态方法。用该法可测定总反应性铝、总单核铝[Ala]和稳定性单核铝[Ali],由总反应性铝减去总单核铝求得酸溶性铝[Als],由总单核铝[Ala]减去稳定单核铝求得不稳定单核铝[Alo],与标准的Driscoll方法(阳离子树脂交换分离-8-羟基喹啉-原子吸收法)进行了比较。结果表明:茜素络合剂(AC)-微分吸附计时电位法灵敏度较高,铁的干扰较少。该法适合于测定含铁量比较高的土壤溶液中的铝形态。 相似文献
910.
The adsorption of antibiotic tetracycline onto silica particles was investigated. The effects of pH, electrolyte concentration
and temperature on the adsorption equilibrium were examined and the data correlated with a dual site adsorption model. Adsorption
of tetracycline onto approximately 9% of the adsorption sites was found to be irreversible, whereas the rest exhibited Langmuir
behaviour. Increasing pH of the solution had a strong negative effect on the adsorbed amounts. Adsorption decreased also with
increasing ionic strength and temperature. The enthalpy and entropy of adsorption were found to be approximately −16 and −25 J/mol,
respectively. 相似文献