全文获取类型
收费全文 | 1280篇 |
免费 | 86篇 |
国内免费 | 340篇 |
专业分类
安全科学 | 111篇 |
废物处理 | 41篇 |
环保管理 | 101篇 |
综合类 | 640篇 |
基础理论 | 281篇 |
污染及防治 | 280篇 |
评价与监测 | 137篇 |
社会与环境 | 80篇 |
灾害及防治 | 35篇 |
出版年
2024年 | 5篇 |
2023年 | 22篇 |
2022年 | 73篇 |
2021年 | 41篇 |
2020年 | 54篇 |
2019年 | 36篇 |
2018年 | 36篇 |
2017年 | 60篇 |
2016年 | 56篇 |
2015年 | 66篇 |
2014年 | 80篇 |
2013年 | 92篇 |
2012年 | 99篇 |
2011年 | 129篇 |
2010年 | 81篇 |
2009年 | 88篇 |
2008年 | 81篇 |
2007年 | 56篇 |
2006年 | 67篇 |
2005年 | 50篇 |
2004年 | 77篇 |
2003年 | 93篇 |
2002年 | 72篇 |
2001年 | 38篇 |
2000年 | 32篇 |
1999年 | 24篇 |
1998年 | 12篇 |
1997年 | 25篇 |
1996年 | 13篇 |
1995年 | 8篇 |
1994年 | 11篇 |
1993年 | 8篇 |
1992年 | 7篇 |
1991年 | 2篇 |
1990年 | 5篇 |
1989年 | 4篇 |
1988年 | 2篇 |
1983年 | 1篇 |
排序方式: 共有1706条查询结果,搜索用时 15 毫秒
931.
黄孢原毛平革菌(Phanerochaete chrysosporium)对Pb~(2+)的生物吸附特性及吸附机理 总被引:2,自引:2,他引:0
研究了非活性黄孢原毛平革菌(Phanerochaete chrysosporium)菌丝球对Pb2+的吸附特性及吸附机理.结果表明,菌丝球对Pb2+的吸附是单分子层吸附,Langmuir模型比Freundlich模型更适合于描述Pb2+在菌丝球上的吸附平衡.菌丝球吸附Pb2+的过程可以分为初始的快速吸附和随后的缓慢吸收2个阶段,并可以用二级动力学模型来描述.在菌丝球吸附Pb2+的过程中虽然存在粒内扩散,但它不是吸附过程的限速步骤.Pb2+的生物吸附过程是放热过程,其吸附活化能为-35.78kJ/mol,Pb2+的吸附热与化学反应热相近,为-44.45 kJ/mol.该生物吸附至少存在2种机理:菌体表面一些含氧基团对Pb2+的络合作用;Pb2+与细胞表面H+的离子交换. 相似文献
932.
Changes of main secondary metabolites in leaves of Ginkgo biloba in response
to ozone fumigation 总被引:1,自引:0,他引:1
HE Xingyuan HUANG Wei CHEN Wei DONG Tian LIU Changbing CHEN Zhenju XU Sheng RUAN Yanan 《环境科学学报(英文版)》2009,21(2):199-203
To investigate the effect of elevated O3 on the accumulation of main secondary metabolites in leaves of Ginkgo biloba L., four-year-old trees were exposed in open-top chambers with ambient air and the air with twice ambient O3 concentration in Shenyang in 2006.Elevated O3 increased the concentrations of terpenes, but decreased the concentrations of phenolics in G.biloba leaves.The results showed that secondary compounds from G.biloba leaves responded to the elevated O3 exposure in a different way when compared to previous studies which showed elevated O3 increased the concentrations of phenolics but had no effect on the terpenes in leaves of other deciduous trees.Furthermore, reduced synthesis of phenolics may decrease the resistance of G.biloba to O3 and other environmental factors.On the other hand, the induced synthesis of terpenes may enhance the antioxidant abilities in G.biloba leaves at the end of O3 fumigation. 相似文献
933.
934.
935.
A 700-year paleoecological record of boreal ecosystem responses to climatic variation from Alaska 总被引:1,自引:0,他引:1
Tinner W Bigler C Gedye S Gregory-Eaves I Jones RT Kaltenrieder P Krähenbühl U Hu FS 《Ecology》2008,89(3):729-743
Recent observations and model simulations have highlighted the sensitivity of the forest-tundra ecotone to climatic forcing. In contrast, paleoecological studies have not provided evidence of tree-line fluctuations in response to Holocene climatic changes in Alaska, suggesting that the forest-tundra boundary in certain areas may be relatively stable at multicentennial to millennial time scales. We conducted a multiproxy study of sediment cores from an Alaskan lake near the altitudinal limits of key boreal-forest species. Paleoecological data were compared with independent climatic reconstructions to assess ecosystem responses of the forest tundra boundary to Little Ice Age (LIA) climatic fluctuations. Pollen, diatom, charcoal, macrofossil, and magnetic analyses provide the first continuous record of vegetation fire-climate interactions at decadal to centennial time scales during the past 700 years from southern Alaska. Boreal-forest diebacks characterized by declines of Picea mariana, P. glauca, and tree Betula occurred during the LIA (AD 1500-1800), whereas shrubs (Alnus viridis, Betula glandulosa/nana) and herbaceous taxa (Epilobium, Aconitum) expanded. Marked increases in charcoal abundance and changes in magnetic properties suggest increases in fire importance and soil erosion during the same period. In addition, the conspicuous reduction or disappearance of certain aquatic (e.g., Isoetes, Nuphar, Pediastrum) and wetland (Sphagnum) plants and major shifts in diatom assemblages suggest pronounced lake-level fluctuations and rapid ecosystem reorganization in response to LIA climatic deterioration. Our results imply that temperature shifts of 1-2 degrees C, when accompanied by major changes in moisture balance, can greatly alter high-altitudinal terrestrial, wetland, and aquatic ecosystems, including conversion between boreal-forest tree line and tundra. The climatic and ecosystem variations in our study area appear to be coherent with changes in solar irradiance, suggesting that changes in solar activity contributed to the environmental instability of the past 700 years. 相似文献
936.
937.
Xue Qiqi Zou Minghui Guo Junjie Teng Qiao Zhang Qiqi Sheng Lingwei Xu Sijia Fang Can Yao Ning Li Yuanyuan Zhao Jinhong 《Environmental science and pollution research international》2023,30(2):3045-3055
Environmental Science and Pollution Research - Dust in the home environment is thought to be a potential trigger for increasing allergic diseases, such as allergic rash, rhinitis, asthma, and other... 相似文献
938.
Dongqi Wen Wenjuan Zhai Sheng Xiang Zhice Hu Tongchuan Wei 《Journal of the Air & Waste Management Association (1995)》2017,67(11):1229-1239
Determination of the effect of vehicle emissions on air quality near roadways is important because vehicles are a major source of air pollution. A near-roadway monitoring program was undertaken in Chicago between August 4 and October 30, 2014, to measure ultrafine particles, carbon dioxide, carbon monoxide, traffic volume and speed, and wind direction and speed. The objective of this study was to develop a method to relate short-term changes in traffic mode of operation to air quality near roadways using data averaged over 5-min intervals to provide a better understanding of the processes controlling air pollution concentrations near roadways. Three different types of data analysis are provided to demonstrate the type of results that can be obtained from a near-roadway sampling program based on 5-min measurements: (1) development of vehicle emission factors (EFs) for ultrafine particles as a function of vehicle mode of operation, (2) comparison of measured and modeled CO2 concentrations, and (3) application of dispersion models to determine concentrations near roadways. EFs for ultrafine particles are developed that are a function of traffic volume and mode of operation (free flow and congestion) for light-duty vehicles (LDVs) under real-world conditions. Two air quality models—CALINE4 (California Line Source Dispersion Model, version 4) and AERMOD (American Meteorological Society/U.S. Environmental Protection Agency Regulatory Model)—are used to predict the ultrafine particulate concentrations near roadways for comparison with measured concentrations. When using CALINE4 to predict air quality levels in the mixing cell, changes in surface roughness and stability class have no effect on the predicted concentrations. However, when using AERMOD to predict air quality in the mixing cell, changes in surface roughness have a significant impact on the predicted concentrations.
Implications: The paper provides emission factors (EFs) that are a function of traffic volume and mode of operation (free flow and congestion) for LDVs under real-world conditions. The good agreement between monitoring and modeling results indicates that high-resolution, simultaneous measurements of air quality and meteorological and traffic conditions can be used to determine real-world, fleet-wide vehicle EFs as a function of vehicle mode of operation under actual driving conditions. 相似文献
939.
Effects of temperature parameters on thermal-optical analysis of organic and elemental carbon in aerosol 总被引:1,自引:0,他引:1
Thermal-optical analysis (TOA) is a popular method to determine aerosol elemental carbon (EC) and organic carbon (OC) collected on quartz fiber filter. However, temperature protocol adopted in TOA has great effects on OC and EC results. The purpose of this study is to investigate and quantify the effects of maximum temperature (T(max)) and residence time (RT) for each step in helium stage on ECOC measurements. Fourteen typical source samples and 20 ambient samples were collected and six temperature programs were designed for this study. It was found that EC value decreases regularly as T(max ) ascends, i.e., EC results from T(max) of 650 degrees C, 750 degrees C and 850 degrees C are 0.89 +/- 0.06, 0.76 +/- 0.10, 0.62 +/- 0.13 times EC value from T( max) of 550 degrees C, respectively, and the magnitude of EC drop (EC(d), percent) is significantly correlated with OC abundance in total carbon (R(OC/TC)), expressed as EC(d) = 66.8R(OC/TC)-14.4 (r = 0.87); pyrolized OC(POC) values are also sensitive to T(max), but there are various trends for samples with different OC constituents. On average of the samples studied here, prolonged RT reduces EC values by only 3%, almost negligible compared to the effect of T(max), and reduces POC by 9%, much less than that by previous report. 相似文献
940.