全文获取类型
收费全文 | 1312篇 |
免费 | 95篇 |
国内免费 | 413篇 |
专业分类
安全科学 | 92篇 |
废物处理 | 92篇 |
环保管理 | 93篇 |
综合类 | 754篇 |
基础理论 | 207篇 |
环境理论 | 1篇 |
污染及防治 | 433篇 |
评价与监测 | 55篇 |
社会与环境 | 54篇 |
灾害及防治 | 39篇 |
出版年
2024年 | 1篇 |
2023年 | 27篇 |
2022年 | 96篇 |
2021年 | 81篇 |
2020年 | 65篇 |
2019年 | 42篇 |
2018年 | 46篇 |
2017年 | 77篇 |
2016年 | 63篇 |
2015年 | 75篇 |
2014年 | 122篇 |
2013年 | 154篇 |
2012年 | 122篇 |
2011年 | 118篇 |
2010年 | 102篇 |
2009年 | 73篇 |
2008年 | 88篇 |
2007年 | 63篇 |
2006年 | 58篇 |
2005年 | 34篇 |
2004年 | 31篇 |
2003年 | 32篇 |
2002年 | 32篇 |
2001年 | 30篇 |
2000年 | 33篇 |
1999年 | 29篇 |
1998年 | 21篇 |
1997年 | 22篇 |
1996年 | 17篇 |
1995年 | 16篇 |
1994年 | 13篇 |
1993年 | 17篇 |
1992年 | 5篇 |
1991年 | 4篇 |
1990年 | 4篇 |
1989年 | 2篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1985年 | 2篇 |
1973年 | 1篇 |
排序方式: 共有1820条查询结果,搜索用时 234 毫秒
571.
Yan Zhang Meng Wang Shunyu Kang Tingting Pan Hua Deng Wenpo Shan Hong He 《环境科学学报(英文版)》2021,33(6):17-26
The control of ethyl acetate emissions from fermentation and extraction processes in the pharmaceutical industry is of great importance to the environment. We have developed three Mn2O3 catalysts by using different Mn precursors (MnCl2, Mn(CH3COO)2, MnSO4), named as Mn2O3-Cl, -Ac, -SO4. The tested catalytic activity results showed a sequence with Mn precursors as: Mn2O3-Cl > Mn2O3-Ac > Mn2O3-SO4. The Mn2O3-Cl catalyst reached a complete ethyl acetate conversion at 212℃ (75℃ lower than that of Mn2O3-SO4), and this high activity 100% could be maintained high at 212℃ for at least 100 hr. The characterization data about the physical properties of catalysts did not show an obvious correlation between the structure and morphology of Mn2O3 catalysts and catalytic performance, neither was the surface area the determining factor for catalytic activity in the ethyl acetate oxidation. Here we firstly found there is a close linear relationship between the catalytic activity and the amount of lattice oxygen species in the ethyl acetate oxidation, indicating that lattice oxygen species were essential for excellent catalytic activity. Through H2 temperature-programmed reduction (H2-TPR) results, we found that the lowest initial reduction temperature over the Mn2O3-Cl had stronger oxygen mobility, thus more oxygen species participated in the oxidation reaction, resulting in the highest catalytic performance. With convenient preparation, high efficiency, and stability, Mn2O3 prepared with MnCl2 will be a promising catalyst for removing ethyl acetate in practical application. 相似文献
572.
Yujing Zhang Jie Li Jianjun Li Xiaole Pan Wei Wang Lili Zhu Zixi Wang Xueshun Chen Wenyi Yang Zifa Wang 《环境科学学报(英文版)》2022,34(4):514-525
Spatiotemporal variations of ozone (O3) taken from the Copernicus Atmosphere Monitoring Service (CAMS) and the second Modern-Era Retrospective Analysis for Research and Applications (MERRA-2) were intercompared and evaluated with ground and ozone-sonde observations over China in 2018 and 2019. Intercomparison of the surface ozone from CAMS and MERRA-2 reanalysis showed significant negative bias (CAMS minus MERRA-2, same below) at Tibetan Plateau of up to 80 µg/m3, and the average R2 was about 0.6 across China. Evaluated with the ground observations from China National Environmental Monitoring Center (CNEMC), we found that CAMS and MERRA-2 reanalysis were capable of capturing the key patterns of monthly and diurnal variations of surface ozone over China except for the western region, and MERRA-2 overestimated the observations compared to CAMS. Vertically, the CAMS profiles overestimated the ozone-sonde from the World Ozone and Ultraviolet Radiation Data Center (WOUDC) above 200 hPa with the magnitude reaching up to 150 µg/m3, while little bias was found between the reanalysis and observations below 200 hPa. Intercomparison drawn from the vertical distribution between CAMS and MERRA-2 reanalysis showed that the negative bias appeared throughout the troposphere over China, while the positive bias emerged in the upper troposphere and lower stratosphere (UTLS) with high order of magnitude exceeding 100 µg/m3, indicating large uncertainties at higher altitudes. In summary, we concluded that CAMS reanalysis showed better agreement with the observations in contrast to MERRA-2, and the large discrepancy especially at higher altitudes between these two reanalysis datasets could not be ignored. 相似文献
573.
生态护岸是目前河、湖治理与修复过程中削减面源氮营养盐的重要措施之一。而筛选高效、低耗的生态护岸基质材料是其关键环节。通过优化复配矿化垃圾、沸石和砾石,研制一种基于矿化垃圾的新型强化脱氮生态护岸基质材料,并从其透水和持水性、抗剪、抗压和抗冲刷性、生态安全性、植被相容性和氮削减特性等方面对该材料进行了性能评定。结果表明:该新型基质材料的透水(渗透系数为1.31~2.55 cm/min)、持水(持水度为5.87%~8.02%)、抗剪(抗剪强度大于60 kPa)、抗压(抗压强度大于380 kPa)以及抗冲刷的性能均满足生态护岸基质材料的要求;发光细菌毒理实验证实其生态安全性;该材料适于护岸植被芦苇、鸢尾和麦冬的生长;具有优良的氮削减性能(氨氮和总氮的削减率分别为95%和70%)。静态经济评价表明,该材料具有明显的成本优势。该新型材料的研制对于生态护岸脱氮功能拓展以及解决河湖治理中面临的"氮超标"问题具有现实意义。 相似文献
574.
17α-Ethynylestradiol(EE2) in natural waters may cause adverse effects on organisms due to its high estrogenic potency. Laboratory studies were performed to study the effects of a local humic acid(LHA), fulvic acid(LFA) and Aldrich humic acid(AHA) on the photochemical behavior and estrogenic potency of EE2. Here photolytic experiments demonstrated that pure aqueous EE2 could undergo direct and self-sensitized photodegradation at a global rate of 0.0068 hr~(-1).Photodegradation rate of EE2 in 5.0 mg/L dissolved humic substances(DHS) was determined to be 0.0274, 0.0296 and 0.0254 hr~(-1) for LHA, LFA and AHA, respectively. Reactive oxygen species(ROS) and triplet dissolved humic substances(~3DHS*) scavenging experiments indicated that the promotion effect of DHS on EE2 photodegradation was mainly aroused by the reactions of HOU(35%–50%),~1O_2(10%) andDHS*(22%–34%). However, the photodegradation of EE2 could also be inhibited when DHS exceeded the threshold of 10 mg/L. Three hydroxylation products of EE2 were identified using GC–MS and their formation pathways were also proposed. In vitro estrogenicity tests showed that EE2 was transformed into chemicals without estrogenic potency. These findings could extend our knowledge on the photochemical behaviors of steroid estrogens in sunlit natural waters. 相似文献
575.
为考察江苏省南部地区重点排放源对南京市秋季细颗粒物(PM_(2.5))的贡献率及O_3生成敏感性,采用强力法针对特定排放源及污染物设置不同的排放情景,利用化学传输模拟系统Models-3/Community Multi-scale Air Quality(CMAQ)分析模拟区域内不同情景下地表PM_(2.5)及O_3浓度变化。2012年10月,电厂、钢铁和水泥的污染物排放对南京市PM_(2.5)浓度的平均贡献率分别为6.0%、25.5%和15.9%,对国控站点的贡献率分别为7.2%、17.7%和16.2%。钢铁对下风向区域的地表PM_(2.5)浓度的影响显著高于电厂及水泥部门的排放。从不同情境下模拟O_3地表浓度变化结果看出,南京市城区及下风向区域的O_3浓度随VOC排放削减降低,随NO_x排放削减升高,因而判定南京市秋季O_3生成属于VOC控制区。 相似文献
576.
577.
578.
地形、树种和土壤属性对喀斯特山区土壤胞外酶活性的影响 总被引:6,自引:2,他引:4
土壤胞外酶在生态系统生物地球化学循环过程中扮演着重要角色,然而关于土壤胞外酶活性的主控因子研究还不够深入,特别是在偏碱性的钙质土壤区域相关研究尤其缺乏.本研究以典型喀斯特山区(木论国家级自然保护区)的林地为研究对象,采集不同地形条件(不同坡位和坡向)、不同树种(厚壳桂和伞花木)下的表层土壤(0~15 cm),测定了与碳、氮、磷循环相关的6种水解酶的活性及相关土壤理化性质.研究运用方差分解,并结合多响应置换过程以及冗余分析技术分析了地形、树种和土壤理化性质对土壤酶活性的影响.结果表明,坡位对土壤酶活性有显著影响.树种和坡向对土壤酶活性的影响不显著.方差分解结果表明,地形、树种和土壤理化性质共同解释了土壤酶活性变化的55.3%,其中土壤因子是影响酶活性改变的主要因子,解释了44.2%的变异.而冗余分析的结果进一步表明在土壤因子中,pH、总氮和无机氮是影响土壤酶活性变化的主要指标.研究首次量化了喀斯特地区小尺度内地形、树种及土壤理化性质对土壤酶活性变化的影响.研究也说明了在喀斯特山区小尺度内土壤酶活性的变化可由土壤理化性质来表征. 相似文献
579.
580.
非常规突发事件应急指挥组织结构研究 总被引:2,自引:1,他引:1
针对目前我国非常规突发事件应急响应过程中存在组织成员职责不明、关系不顺,难以实现快速联动和协同配合的问题,依据我国应急管理规章制度,以开放理性系统视角分析应急指挥组织结构(ECOS)的特点,基于组织理论提出契合行政级别的、具有闭环反馈的ECOS。以2010年夏三峡区域遭遇长江流域全流域性洪水为背景,基于提出的组织结构对三峡水库防洪应急指挥组织进行规范设置。研究结果表明,ECOS中各级政府应急部门采用官僚结构,现场指挥部采用项目小组结构,会商小组采用任务小组结构,整体构成矩阵结构。在稳定、理性、规范、高效的基础上,更具弹性和灵活性。这种刚性和柔性复合的、有层次和权威的、开放和权变的ECOS更适合我国国情以应对非常规突发事件。 相似文献