全文获取类型
收费全文 | 1206篇 |
免费 | 153篇 |
国内免费 | 296篇 |
专业分类
安全科学 | 262篇 |
废物处理 | 35篇 |
环保管理 | 220篇 |
综合类 | 691篇 |
基础理论 | 159篇 |
环境理论 | 7篇 |
污染及防治 | 76篇 |
评价与监测 | 60篇 |
社会与环境 | 77篇 |
灾害及防治 | 68篇 |
出版年
2024年 | 8篇 |
2023年 | 47篇 |
2022年 | 73篇 |
2021年 | 63篇 |
2020年 | 89篇 |
2019年 | 63篇 |
2018年 | 55篇 |
2017年 | 67篇 |
2016年 | 80篇 |
2015年 | 63篇 |
2014年 | 70篇 |
2013年 | 93篇 |
2012年 | 108篇 |
2011年 | 99篇 |
2010年 | 72篇 |
2009年 | 62篇 |
2008年 | 51篇 |
2007年 | 74篇 |
2006年 | 58篇 |
2005年 | 44篇 |
2004年 | 48篇 |
2003年 | 45篇 |
2002年 | 25篇 |
2001年 | 29篇 |
2000年 | 17篇 |
1999年 | 11篇 |
1998年 | 16篇 |
1997年 | 11篇 |
1996年 | 14篇 |
1995年 | 9篇 |
1994年 | 11篇 |
1993年 | 7篇 |
1992年 | 7篇 |
1991年 | 6篇 |
1990年 | 3篇 |
1989年 | 6篇 |
1988年 | 5篇 |
1987年 | 4篇 |
1986年 | 5篇 |
1985年 | 5篇 |
1984年 | 2篇 |
1983年 | 4篇 |
1982年 | 4篇 |
1981年 | 6篇 |
1980年 | 3篇 |
1979年 | 4篇 |
1973年 | 1篇 |
1972年 | 1篇 |
1971年 | 3篇 |
1970年 | 2篇 |
排序方式: 共有1655条查询结果,搜索用时 265 毫秒
921.
社会技术转型的多层视角(MLP)是转型理论的最新进展,它认为转型是由三个层面——微观层的技术利基,中观层的社会技术体制和宏观层的大环境——相互作用引起的一个非线性的演化过程。该思路通过分析技术和社会因素之间的互动关系,寻求理解社会技术体制的长期变化。本文以MLP为分析思路,研究我国电力系统现行体制已经发生的动态变化;并从短期,中期和长期三个时间维度,对我国低碳电力系统转型路径提出一个概念性的分析框架。短期的转变路径,延续和发展现有体制结构和治理模式,通过体制内行为主体有意识地调整创新活动和发展的方向,来解决体制内部矛盾和压力,实现政府2020年的减排目标和可再生能源目标。中期的重构路径,基本实现电源结构实质性改变,火力发电比例逐步下降,可再生能源发电对其主导地位形成冲击和挑战,电力系统呈现百花齐放百家争鸣之势态。长期的重置路径通过新的低碳能源技术创新的质的突破和飞跃,实现高煤高碳的电力体系由新的低碳体制取代这一长期目标。本文从理论和方法上丰富了目前我国低碳转型的讨论,对政策制定者和相关的行为主体也可提供一种有益的参考。 相似文献
922.
Xiao-Song He Bei-Dou Xi Xiang Li Hong-Wei Pan Da An Shuo-Guo Bai Dan Li Dong-Yu Cui 《Chemosphere》2013
The present several humification indexes cannot provide the whole fluorescence information on organic matter composition and the evaluation results from them are inconsistent sometimes. In this study, fluorescence excitation–emission matrix spectra coupled with parallel factor analysis and fluorescence regional integration analysis were utilized to investigate organic matter humification, and the projection pursuit cluster (PPC) model was applied to form a suitable index for overcoming the difficulties in multi-index evaluation. The result showed that the ratio between the volume of humic- and fulvic-like fluorescence region and the volume of protein-like fluorescence region not only revealed the heterogeneity of organic matter, but also provided more accurate information on organic matter humification. In addition, the results showed that the PPC model could be used to characterize integrally the humification, and the projected characteristic value calculated from the PPC model could be used as the integrated humification evaluation index. 相似文献
923.
Yan Zhang Jun W. Liu Wen J. Zheng Lei Wang Hong Y. Zhang Guo Z. Fang 《Journal of environmental science and health. Part. B》2013,48(2):127-133
In this study, an enzyme-linked immunosorbent assay (ELISA) was optimized and applied to the determination of endosulfan residues in 20 different kinds of food commodities including vegetables, dry fruits, tea and meat. The limit of detection (IC15) was 0.8 μg kg?1 and the sensitivity (IC50) was 5.3 μg kg?1. Three simple extraction methods were developed, including shaking on the rotary shaker at 250 r min?1 overnight, shaking on the rotary shaker for 1 h and thoroughly mixing for 2 min. Methanol was used as the extraction solvent in this study. The extracts were diluted in 0.5% fish skin gelatin (FG) in phosphate-buffered saline (PBS) at various dilutions in order to remove the matrix interference. For cabbage (purple and green), asparagus, Japanese green, Chinese cabbage, scallion, garland chrysanthemum, spinach and garlic, the extracts were diluted 10-fold; for carrots and tea, the extracts were diluted 15-fold and 900-fold, respectively. The extracts of celery, adzuki beans and chestnuts, were diluted 20-fold to avoid the matrix interference; ginger, vegetable soybean and peanut extracts were diluted 100-fold; mutton and chicken extracts were diluted 10-fold and for eel, the dilution was 40-fold. Average recoveries were 63.13–125.61%. Validation was conducted by gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS). The results of this study will be useful to the wide application of an ELISA for the rapid determination of pesticides in food samples. 相似文献
924.
925.
Dongli Wang Paramjit Behniwal Ruifang Fan Ho Sai Simon Ip Jianwen She 《Journal of environmental science and health. Part. B》2013,48(3):177-182
Urinary dialkyl phosphate metabolites (DAPs) are used as biomarkers to evaluate human exposure to organophosphate pesticides. The objective was to evaluate potential artifacts in urinary DAPs analysis during sample preparation and method calibration. Diluted urine pools were commonly used to prepare calibration standards to minimize the effects due to the complexity of urine matrix. Matrix effects on measurements of DAPs were evaluated by spiking known amount of standards into distilled water, synthetic urine and diluted urine pool. Different matrices resulted in similar concentrations detected for all target compounds, except dimethylphosphate (DMP) with the deviation of measurement as large as eight times the spiked amount. In this study, we also found that urinary particles, which usually appeared after thawing frozen human urine samples, could affect the measurements of DAPs, especially DMP and diethylthiophosphate (DETP). Results of DAPs measurements in three types of sample matrices, i.e. urine without particles, urine with particles and particles only were compared. DETP could be subject to large error during this preparation step. The use of deuterated and 13C12-labeled DAPs as internal standards is also evaluated. Overall, these issues can cause misidentification and inaccuracies, which may significantly affect the data quality. 相似文献
926.
为了提高吸附剂对乙烯气体的吸附量,对常见的MCM-41分子筛进行了过渡金属离子改性研究。通过镍离子交换实验,确定了改性条件,改性后的样品对乙烯的吸附行为发生改变。使用镍离子改性后的MCM-41在常温常压下对乙烯的最大吸附量为可达416cm3/g,约为商用颗粒活性炭的6倍,远高于其他文献的报道。吸附质的检测结果说明乙烯在其吸附过程中发生多聚反应,高碳数的直链烯烃为最终产物。CO原位红外吸附的引人证实经过热处理后,一价镍能在镍离子改性后的MCM-41样品中形成并成为乙烯聚合反应的活性中心。 相似文献
927.
生物强化组合工艺处理河水的三维荧光及生物多样性分析 总被引:2,自引:0,他引:2
通过对受污染地表水进行生物滤池-臭氧预氧化-生物活性炭滤池工艺处理,考察生物强化条件下该项工艺对河水中主要污染物的净化效果,并采用EEM光谱技术进行了溶解性有机物变化和去除规律分析,利用PCR-DGGE技术进行各单元中微生物多样性对比分析。结果表明,生物强化组合工艺系统出水水质主要指标已达到/接近地表水环境质量标准(GB 3838-2002)Ⅳ类限值,生物强化滤池填料中微生物多样性指数和物种数均高于其他工艺单元。受污染河水DOM中主要的荧光物质有类芳香族蛋白质(荧光峰A、B和E)及类腐殖酸(荧光峰C)及类富里酸(荧光峰D),其中,A峰、B峰与E峰的中心位置分别位于225/340 nm、275/336 nm和225/298 nm,各特征荧光峰强度发生明显改变表明,污水中溶解性有机物的含量随系统处理过程而变化。 相似文献
928.
餐厨垃圾连续堆肥处理系统中试研究 总被引:1,自引:0,他引:1
餐厨垃圾是影响城市环境重要的污染源,其处理尤其是就地堆肥处理近年来受到重视.为了利用园林绿化基质作为餐厨垃圾堆肥的水分调节材料,按照1:1体积比进行连续堆肥,研究添加园林绿化基质对餐厨垃圾堆肥过程中理化指标的影响,为餐厨垃圾无害化处理提供科学依据和技术指导.结果表明,物料堆肥升温启动迅速,第3天就达到50℃,高温持续10 d以上,达到无害化要求;堆肥最终减容率达到53%以上,减量化效果明显;物料总氮和总磷含量呈升高趋势,总有机质含量降低,肥料营养元素含量在6%以上,符合有机肥国家标准(NY525-2002).总的来说,园林绿化基质作为调理剂与餐厨垃圾联合堆肥方法可行,减量化效果好,品质符合标准. 相似文献
929.
930.
我国自然灾害类应急预案评价方法研究(Ⅱ):责任矩阵评价 总被引:4,自引:2,他引:2
在突发事件应急过程中,由于分工不明、责任不清导致的部门间或者责任人之间的推诿扯皮等现象影响应急行动的高效有序开展,甚至会导致应急行动失败。因此,在应急预案中各应急部门(人员)责任分配是否适当是应急能否成功的关键。为解决该问题,笔者引入项目管理中的责任矩阵方法(Responsibility Matrix)。首先,根据应急的特点,定义直接责任(R)、支持(S)、建议(A)、约束(P)4种责任类型,确定了责任划分的原则;然后,总结出我国自然灾害类应急预案主要包含41种角色类型,并在该基础上建立了应急程序和应急人员间的责任矩阵及评价准则;进而采用上述方法分析一个实际的地震应急预案,对该应急预案的责任矩阵进行评价,最终确定其需要加强和完善的方面,为制定或修订应急预案提供参考。 相似文献