全文获取类型
收费全文 | 21656篇 |
免费 | 487篇 |
国内免费 | 4439篇 |
专业分类
安全科学 | 816篇 |
废物处理 | 1529篇 |
环保管理 | 2120篇 |
综合类 | 7752篇 |
基础理论 | 5001篇 |
环境理论 | 6篇 |
污染及防治 | 6053篇 |
评价与监测 | 1433篇 |
社会与环境 | 1309篇 |
灾害及防治 | 563篇 |
出版年
2024年 | 1篇 |
2023年 | 197篇 |
2022年 | 576篇 |
2021年 | 479篇 |
2020年 | 351篇 |
2019年 | 359篇 |
2018年 | 1878篇 |
2017年 | 1851篇 |
2016年 | 1663篇 |
2015年 | 812篇 |
2014年 | 977篇 |
2013年 | 1277篇 |
2012年 | 1462篇 |
2011年 | 2491篇 |
2010年 | 1516篇 |
2009年 | 1433篇 |
2008年 | 1749篇 |
2007年 | 1903篇 |
2006年 | 656篇 |
2005年 | 500篇 |
2004年 | 383篇 |
2003年 | 498篇 |
2002年 | 480篇 |
2001年 | 326篇 |
2000年 | 352篇 |
1999年 | 401篇 |
1998年 | 337篇 |
1997年 | 311篇 |
1996年 | 295篇 |
1995年 | 260篇 |
1994年 | 177篇 |
1993年 | 156篇 |
1992年 | 113篇 |
1991年 | 94篇 |
1990年 | 64篇 |
1989年 | 54篇 |
1988年 | 44篇 |
1987年 | 19篇 |
1986年 | 22篇 |
1985年 | 11篇 |
1984年 | 22篇 |
1983年 | 18篇 |
1982年 | 10篇 |
1981年 | 2篇 |
1935年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 62 毫秒
21.
Lei Jun & Zhang Xiaolei Xinjiang Institute of Ecology Geography Chinese Academy of Sciences Urumqi China Institute of Geography Science Natural Resources Research Chinese Academy of Sciences Beijing .China 《中国人口.资源与环境(英文版)》2005,3(3)
As a special basic economic region in China, Xinjiang is situated in the arid area in the Northwest China. Oasis agriculture is the basis of the national economy. The development of oasis agriculture helps to accelerate the development of economy, social and environment. After 50 years of practice, from 1949 to 2002, oasis agriculture in Xinjiang enhanced rapidly the scale of agricultural industry and had great changes in its structure. The amount of cultivated area rose from 120.97*102 ha t… 相似文献
22.
关中地区飑线天气的预测及灾害对策探讨 总被引:1,自引:0,他引:1
对1961~1990年发生在陕西省关中地区的飑线天气及其灾害进行了统计分析,并从天气形势背景方面对飑线的发生发展进行了研究和分析,同时就飑线的预测和防灾对策进行了探讨。 相似文献
23.
Zhang Yuqing Zhan Chengcheng Wang Hui Gao Ya 《Environment, Development and Sustainability》2022,24(8):9777-9808
Environment, Development and Sustainability - This study analyzes the evolution of the land use structure, demographic reconstruction, and social reconstruction of Dachangshan Island, Changhai... 相似文献
24.
Feng Jingchun Tang YunQing Xue Song Zhang Ke 《Environment, Development and Sustainability》2022,24(1):138-155
Environment, Development and Sustainability - The PPP mode of rural water environment governance was conducive to attracting social capital for giving full play to the decisive role of the market... 相似文献
25.
26.
Russian Journal of Ecology - The aim of this study is to explore the effects of the litter cover thickness and cleaning methods on seed germination and seedling growth of Pinus densata. The overall... 相似文献
27.
Zhang Xu Yang Huanhuan Sun Ruirui Cui Meihua Sun Ning Zhang Shouwen 《Environment, Development and Sustainability》2022,24(9):10997-11010
Environment, Development and Sustainability - Heavy metal pollution has attracted more attention due to the toxicity and migration characteristics, which has close relationship with soil... 相似文献
28.
Liuwei Kong Min Hu Qinwen Tan Miao Feng Yu Qu Junling An Yuanhang Zhang Xingang Liu Nianliang Cheng 《环境科学学报(英文版)》2020,32(1):49-59
To clarify the aerosol hygroscopic growth and optical properties of the Pearl River Delta(PRD)region,integrated observations were conducted in Heshan City of Guangdong Province from October 19 to November 17,2014.The concentrations and chemical compositions of PM_(2.5),aerosol optical properties and meteorological parameters were measured.The mean value of PM_(2.5) increased from less than 35(excellent) to 35-75 μg/m~3(good) and then to greater than 75 μg/m~3(pollution),corresponding to mean PM_(2.5) values of 24.9,51.2,and 93.3 μg/m~3,respectively.The aerosol scattering hygroscopic growth factor(f(RH = 80%)) values were 2.0,2.12,and 2.18 for the excellent,good,and pollution levels,respectively.The atmospheric extinction coefficient(σext)and the absorption coefficient of aerosols(σ_(ap)) increased,and the single scattering albedo(SSA)decreased from the excellent to the pollution levels.For different air mass sources,under excellent and good levels,the land air mass from northern Heshan had lower f(RH) and σ_(sp) values.In addition,the mixed aerosol from the sea and coastal cities had lower f(RH) and showed that the local sources of coastal cities have higher scattering characteristics in pollution periods. 相似文献
29.
The performance of Ce-OMS-2 catalysts was improved by tuning the fill percentage in the hydrothermal synthesis process to increase the oxygen vacancy density. The Ce-OMS-2 samples were prepared with different fill percentages by means of a hydrothermal approach (i.e. 80%, 70%, 50% and 30%). Ce-OMS-2 with 80% fill percentage (Ce-OMS-2-80%) showed ozone conversion of 97%, and a lifetime experiment carried out for more than 20?days showed that the activity of the catalyst still remained satisfactorily high (91%). For Ce-OMS-2-80%, Mn ions in the framework as well as K ions in the tunnel sites were replaced by Ce4+, while for the others only Mn ions were replaced. O2-TPD and H2-TPR measurements proved that the Ce-OMS-2-80% catalyst possessed the greatest number of mobile surface oxygen species. XPS and XAFS showed that increasing the fill percentage can reduce the AOS of Mn and augment the amount of oxygen vacancies. The active sites, which accelerate the elimination of O3, can be enriched by increasing the oxygen vacancies. These findings indicate that increasing ozone removal can be achieved by tuning the fill percentage in the hydrothermal synthesis process. 相似文献
30.
Water-uptakes of pure sodium carbonate(Na_2CO_3),pure β-alanine and internally mixedβ-alanine/Na_2CO_3 aerosol particles with different mole ratios are first monitored using attenuated total reflectance Fourier transform infrared spectroscopy(ATR-FTIR) technique.For pure Na_2CO_3 aerosol particles,combining the absorptions at 877 and 1422 cm-1 with abrupt water loss shows the efflorescence relative humidity(ERH) of 62.9%–51.9%.Upon humidifying,solid Na_2CO_3 firstly absorbs water to from Na_2CO_3·H2 O crystal at 72.0% RH and then deliquesces at 84.5% RH(DRH).As for pure β-alanine particles,the crystallization takes place in the range of 42.4%–33.2% RH and becomes droplets at ~ 88.2% RH.When β-alanine is mixed with Na_2CO_3 at various mole ratios,it shows no efflorescence of Na_2CO_3 whenβ-alanine to Na_2CO_3 mole ratio(OIR) is 2:1.For 1:1 and 1:2 β-alanine/Na_2CO_3 aerosols,the ERHs of Na_2CO_3 are 51.8%–42.3% and 57.1%–42.3%,respectively.While β-alanine crystal appears from 62.7% RH for 2:1 and 59.4% RH for both 1:1 and 1:2 particles and lasts to driest state.On hydration,the DRH is 44.7%–75.2% for Na_2CO_3 with the OIR of 1:1 and 44.7%–69.0%for 1:2 mixture,and those of β-alanine are 74.8% for 2:1 mixture and 68.9% for two others.After the first dehumidification–humidification,all the water contents decrease despite of constituent fraction.And at ~ 92% RH,the remaining water contents are 92%,89% and 82%at ~ 92% RH,corresponding to OIR of 2:1,1:1 and 1:2 mixed system,respectively. 相似文献