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31.
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介绍了小隐孢子虫卵囊的特点及其对人体的危害,分析了pH、混凝剂种类与投加量、电导率和天然有机物含量等对小隐孢子虫卵囊的Zeta电位的影响,总结了混凝-沉淀-过滤和直接过滤对小隐孢子虫卵囊的去除效果,探讨了水温、水质、混凝剂种类与投加量、滤料层组成和滤速等对去除效果的影响。 相似文献
33.
Pesavento M Biesuz R Profumo A Soldi T 《Environmental science and pollution research international》2003,10(5):317-320
SCOPE: The detection and investigation of metal ions bound in strong complexes in natural waters is a difficult task, due to low concentration of the metal ions themselves, and also of the strong ligands, which, moreover, are often not of a well-defined composition. Here, a method is proposed for the investigation of the speciation of metal ions in natural waters. OBJECTIVE AND METHOD: It is based on the sorption of metal ions on strongly sorbing ion exchange resins, i.e. complexing resins. For this reason the method is called Resin Titration. It has been shown in previous investigations that the concentration of metal ion totally sorbed by a particular resin, and its reaction coefficient in the solution phase in the presence of the resin, can be determined from the sorption data using a simple relationship. Here, a data treatment (the Ruzic linearization method) is proposed for also determining the concentration of the ligands responsible for the complex in equilibrium with the resin. RESULTS: The method was applied to data obtained by Resin Titration of a freshwater and a seawater. Copper(II) and aluminium(III) were considered, using Chelex 100 as a titrant, due to its strong sorbing properties towards these metal ions. The results were: the total metal concentration in equilibrium with the resin, the side reaction coefficients, and the concentration of ligands. In all these cases the ligands forming very strong complexes were found to be at concentration lower than that of the metals. CONCLUSION: The Ruzic linearization method allows the determination of the concentration of the ligands forming very strong complexes in equilibrium with Chelex 100. The reaction coefficient was better determined by the calculation method previously proposed for RT. The ligands responsible for the strong complexes were found to be at low concentration, often lower than that of the metal ions considered. The metal in the original sample is partly bound to these ligands, since the complexes are very strong. Only a part of the metal is linked to weaker ligands, or free. 相似文献
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Hollert H Dürr M Holtey-Weber R Islinger M Brack W Färber H Erdinger L Braunbeck T 《Environmental science and pollution research international》2005,12(6):347-360
Goal, Scope and Background In order to evaluate the estrogenic activity of sediments and XAD water extracts of selected sites of the catchment area
of the River Neckar, a river system in Southern Germany, an integrative assessment approach was used to assess the ecological
hazard potential of endocrine-disrupting compounds in sediment and water.
Methods The approach is based on estrogen receptor-mediated vitellogenin synthesis induced in isolated hepatocytes of rainbow trout
and quantified in a non-radioactive dot blot/RNAse protection-assay in parallel to comprehensive chemical analyses of estrogenic
substances.
Results and Discussion Numerous investigated extracts revealed an estrogen activity comparable to that of the positive control (1 nM 17?-estradiol
corresponding to 270 ng/L in the test medium). Based on a concentration factor of 30 in the extracts and a recovery of XAD
resins of approximately 80 %, 17?-estradiol equivalent concentrations between 20 and 26.7 ng/L could be calculated downstream
of a sewage treatment plant (< 0.1 ng/L for a reference site). A comparison of the bioassay-derived Bio-TEQs (toxicity equivalents)
and the Chem-TEQs revealed a high correlation with a Pearson coefficient of 0.85, indicating that the same ranking of the
samples could be obtained with respect to the endocrine disrupting potential with both chemical and bioanalytical analysis.
However, the TEQ concentrations computed from chemical analyses were significantly lower than the bioassay-derived TEQ concentrations.
In fact, in none of the samples, more than 14 % of the vitellogenin-inducing potency could be attributed to the substances
(steroids, alkylphenols, bisphenol A, diethylstilbestrol) analyzed.
A comparison of the endocrine disrupting potential of sediments extracted by the solvents acetone and methanol revealed lower
biological effects for acetone-extracted samples. Possible reasons may be a masking of endocrine effects in acetone extracts
by cytotoxicity, a low extraction efficiency of the solvent acetone, or anti-estrogen potencies of some extracted sediment
compounds.
Using a mass balance approach, the contribution of the compounds analyzed chemically (Chem-TEQs) to the total endocrine activity
(Bio-TEQs) was calculated. Based on the very low detection limits, particularly of the steroids with their high TEF factors,
results revealed that a calculation of the Chem-TEQs is associated with considerable scale inaccuracy: Whereas only 7-15 %
of the biological effectiveness (Bio-TEQs) could be explained by endocrine substances identified above the detection limits,
the assumption of concentrations slightly below the given detection limits would result in a significant over estimation (137-197
%) of the Bio-TEQs. Even the interassay variation of the dot blot assay with different fish donors for primary hepatocyte
(factor 2 - 2.5) is relatively low, when compared to the large range of the Chem-TEQ concentrations (factor 20) obtained when
applying different modes of calculation.
Conclusions and Outlook Overall, only a minor portion of the endocrine activity detected by bioassays could be linked to compounds identified by
chemical analysis. In vitro assays for assessment of endocrine activities are useful as sensitive integrating methods that
provide quantitative estimates of the total activity of particular receptor-mediated responses. Although discrepancies may
also result from different bioanalytical approaches, it is overall likely that bioanalytical and not chemical analytical approaches
give the correct estimate of endocrine disrupting potencies in environmental samples. As a conclusion, assessment of endocrine
disruption based on chemical analysis alone does not appear sufficient and further research into the spectrum of substances
with potential endocrine activity as well as into additive or even synergistic effects in complex environmental samples is
urgently needed. 相似文献
38.
自然资源是可持续发展的基础。完善自然资源资产审计制度,是保护自然资源、践行生态文明的要求。自然资源资产审计的前提是自然资源的确权和量化,是自然资源与自然资源资产在审计上的“融合”。作为自然资源资产审计的依据,相关制度应该对自然资源的确权、计量和有效利用作出合理安排,才能有效抑制资源滥用冲动。但立足于自然资源资产审计实践,综合运用文献研究、个案调查、跨学科研究等方法,分析现行的自然资源制度,没有发现可操作性的自然资源产权制度、计量制度和评价制度,已有制度存在权责不匹配、责任界定不清晰、公众参与有困难、审计指标不健全;制度系统呈现存量不足、增量困难、实践不力,不能适应新时代要求和自然资源合理利用需要。因此,可以从制度存量、增量和协同三条路径实施制度供给侧改革;在完善制度存量方面,可以在经济责任审计规定中嵌入自然资源资产审计内容,完善自然资源资产评价标准、责任制度和审计结果运用办法等;在提高制度增量方面,完善自然资源资产的权利制度、计量制度、信息公开制度和公众参与制度等;同时,通过适时修订审计法、制定自然资源资产法,强化制度协调,以突破自然资源资产的制度瓶颈,方便审计算好“生态账”、把好“生态关”。在自然资源资产制度改革过程中,需要借助决策层和专家力量,摆脱部门立法局限,强化制度协调;同时,制度改革也是一个不断优化的过程,要兼顾公众、个人、政府及其职能部门等多方利益,才能有效满足资源节约型和环境友好型社会的需要。 相似文献
39.
完善的自然资源资产负债表编制体系,能为国家和各级政府摸清“家底”,进行宏观经济管理、资源配置等工作提供重要的数据信息。党的十八届三中全会提出探索编制自然资源资产负债表之后,与此相关的理论研究迅速增加,但针对自然资源资产负债表编制和运用的理论与实践仍存在一些模糊认识;诸如自然资源负债等难以确定的问题。着眼于此,本文对我国自然资源资产负债表的编制现状进行了认真的思考,总结出自然资源资产负债表编制和运用的六个关键问题,即对国际规范SEEA2012和SNA2008的认识问题,对以县级单位为起点的编制主体的认识问题,对单式和复式表格根本区别的认识问题,对实物量和价值量转换难点的认识问题,对自然资源资产负债表信息渠道与平台建设的认识问题,对自然资源资产负债表编制中各部门权责关系的认识问题。以此为基础,本文从国际做法和国内实践两个角度进行了分析,并提出了本文观点:编制和运用自然资源资产负债表,应全面理解、充分借鉴SEEA2012和SNA2008的国际规范;确立以县级及以下政府层级为起点的编制主体;转变为“从单式到复式”的编表思路,坚持使用复式表格;迈出实物量向价值量转化的重要一步,重视价值量核算;建设自然资源数据收集的信息渠道与平台;处理好自然资源资产负债表编制中各部门间的权责关系。本文研究有利于推进自然资源资产负债表编制与运用工作,发挥自然资源资产负债表在我国的生态文明建设中的重要作用。 相似文献
40.
浙江省农业自然资源合理利用战略研究 总被引:1,自引:1,他引:1
陈庆根 《长江流域资源与环境》1998,7(2):159-163
针对浙江省自然资源利用程度高,资源环境压力大,资源浪费和污染等严重问题,根据浙江省资源构成特点,从资源,环境与经济协调发展的观点提出减少非农建设占用耕地,完善基本农田保护工作,绝不以牺牲现有耕地为调整农业产业结构。与此同时,积极开发后备土地资源,补充现有耕地面积;对于水资源必须依法治,管并重,节约与开源相结合,合理利用水资源,着重开发山,海资源和改善农业生态环境等战略措施。 相似文献