全文获取类型
收费全文 | 2260篇 |
免费 | 204篇 |
国内免费 | 735篇 |
专业分类
安全科学 | 221篇 |
废物处理 | 103篇 |
环保管理 | 151篇 |
综合类 | 1453篇 |
基础理论 | 370篇 |
污染及防治 | 564篇 |
评价与监测 | 136篇 |
社会与环境 | 104篇 |
灾害及防治 | 97篇 |
出版年
2024年 | 7篇 |
2023年 | 44篇 |
2022年 | 141篇 |
2021年 | 103篇 |
2020年 | 106篇 |
2019年 | 70篇 |
2018年 | 80篇 |
2017年 | 123篇 |
2016年 | 114篇 |
2015年 | 118篇 |
2014年 | 177篇 |
2013年 | 221篇 |
2012年 | 218篇 |
2011年 | 204篇 |
2010年 | 157篇 |
2009年 | 149篇 |
2008年 | 193篇 |
2007年 | 144篇 |
2006年 | 139篇 |
2005年 | 82篇 |
2004年 | 66篇 |
2003年 | 62篇 |
2002年 | 56篇 |
2001年 | 53篇 |
2000年 | 53篇 |
1999年 | 47篇 |
1998年 | 45篇 |
1997年 | 46篇 |
1996年 | 30篇 |
1995年 | 35篇 |
1994年 | 21篇 |
1993年 | 24篇 |
1992年 | 24篇 |
1991年 | 12篇 |
1990年 | 8篇 |
1989年 | 5篇 |
1988年 | 8篇 |
1987年 | 4篇 |
1986年 | 1篇 |
1985年 | 5篇 |
1984年 | 1篇 |
1983年 | 2篇 |
1982年 | 1篇 |
排序方式: 共有3199条查询结果,搜索用时 286 毫秒
91.
92.
93.
Electrochemical and spectroscopic characteristics of dissolved organic matter in a forest soil profile 总被引:2,自引:0,他引:2
Dissolved organic matter (DOM) represents one of the most mobile and reactive organic compounds in ecosystem and plays an important role in the fate and transport of soil organic pollutants, nutrient cycling and more importantly global climate change. Electrochemical methods were first employed to evaluate DOM redox properties, and spectroscopic approaches were utilized to obtain information concerning its composition and structure. DOM was extracted from a forest soil profile with five horizons. Differential pulse voltammetry indicated that there were more redox-active moieties in the DOM from upper horizons than in that from lower horizons. Cyclic voltammetry further showed that these moieties were reversible in electron transfer. Chronoamperometry was employed to quantify the electron transfer capacity of DOM, including electron acceptor capacity and electron donor capacity, both of which decreased sharply with increasing depth. FT-IR, UV-Vis and fluorescence spectra results suggested that DOM from the upper horizons was enriched with aromatic and humic structures while that from the lower horizons was rich in aliphatic carbon, which supported the findings obtained by electrochemical approaches. Electrochemical approaches combined with spectroscopic methods were applied to evaluate the characteristics of DOM extracted along a forest soil profile. The electrochemical properties of DOM, which can be rapidly and simply obtained, provide insight into the migration and transformation of DOM along a soil profile and will aid in better understanding of the biogeochemical role of DOM in natural environments. 相似文献
94.
通过对采煤塌陷地复垦的潜力调查、分析和评价研究,可以进一步了解塌陷地复垦的潜力空间分布情况、等级状况,提出切实可行的采煤塌陷地复垦建议和对策。本文结合徐州市铜山区实际情况,选取影响采煤塌陷地复垦潜力的地形及水文条件、土壤条件和社会经济条件作为潜力评价因子,采用模糊综合评价法进行铜山区采煤塌陷地复垦潜力评价,依据评价结果把该塌陷区分为四个潜力区,针对不同潜力区塌陷地提出相应的复垦模式。 相似文献
95.
Jingzhou Zhao Hang Li Hongseok Choi Wayne Cai Jeffrey A. Abell Xiaochun Li 《Journal of Manufacturing Processes》2013,15(1):136-140
Real-time monitoring and control of temperature in ultrasonic joining of battery tabs and coupons are important for the quality improvement and cost reduction of battery assembly. However, there have always been difficulties in accurate and real-time measurement of temperature by conventional sensors for practical implementation. In this study, an innovative method is developed to provide an enabling technology for the in situ transient temperature monitoring, which could provide reliable feedback signals for potential control of ultrasonic joining processes. Micro thin film thermocouples (TFTCs) were fabricated on thin silicon substrates, which were then inserted in the welding anvil as a permanent feature so that the sensors were always located about 100 μm directly under the welding spot during joining of multilayer Ni-coated Cu thin sheets for battery assembly. Good repeatability was demonstrated while a temperature rise of up to 650 °C was obtained due to the closeness of the sensors to the welding spot. The inserts with thin film sensors remained functional after welding experiments. This method has a great potential for in situ transient temperature monitoring, and thus the control of ultrasonic joining processes to realize a practical smart joining system. 相似文献
96.
基于遥感监测的黄海绿潮漂移路径及分布面积特征分析 总被引:1,自引:0,他引:1
本文利用2008~2012年的多源卫星遥感序列图像,动态监测各年绿潮发生的漂移路径、影响海域面积,得到各年绿潮漂移趋势、分布面积和最大分布面积出现时间。根据监测结果,划分出影响绿潮漂移路径的关键区域,并分析了2008、2009和2010年关键区域内各年绿潮漂移方向和面积变化情况。 相似文献
97.
98.
99.
100.
绿色化学又称环境友好化学,它是在化学产品的设计、制造和应用过程中运用一套原理和理论来减少或者消除对有害物质的生产和利用的一门学科。绿色化学工艺的目标是用化学的技术和手段去减少或消除那些对人类健康有害的原料、产物、副产物、溶剂和试剂等的产生或应用。催化技术是绿色化学工艺研究及应用的重要手段,简要介绍了绿色化学与催化的关系、催化剂的研究进展及典型实例,并列举了几种新型绿色催化剂,详细分析了其环境友好特性。 相似文献