全文获取类型
收费全文 | 8267篇 |
免费 | 1411篇 |
国内免费 | 2999篇 |
专业分类
安全科学 | 1402篇 |
废物处理 | 177篇 |
环保管理 | 759篇 |
综合类 | 6792篇 |
基础理论 | 1164篇 |
污染及防治 | 762篇 |
评价与监测 | 495篇 |
社会与环境 | 656篇 |
灾害及防治 | 470篇 |
出版年
2024年 | 97篇 |
2023年 | 226篇 |
2022年 | 559篇 |
2021年 | 614篇 |
2020年 | 669篇 |
2019年 | 444篇 |
2018年 | 473篇 |
2017年 | 593篇 |
2016年 | 484篇 |
2015年 | 536篇 |
2014年 | 520篇 |
2013年 | 678篇 |
2012年 | 821篇 |
2011年 | 776篇 |
2010年 | 757篇 |
2009年 | 695篇 |
2008年 | 627篇 |
2007年 | 656篇 |
2006年 | 667篇 |
2005年 | 479篇 |
2004年 | 315篇 |
2003年 | 228篇 |
2002年 | 215篇 |
2001年 | 164篇 |
2000年 | 157篇 |
1999年 | 102篇 |
1998年 | 33篇 |
1997年 | 24篇 |
1996年 | 20篇 |
1995年 | 13篇 |
1994年 | 15篇 |
1993年 | 6篇 |
1992年 | 11篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1988年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
661.
以长江中游城市群的36个城市为例,构建了经济发展、城市化、社会保障、生态环境综合评价指标体系,运用耦合度模型评估了36个城市2011~2013年的耦合度,并利用GIS技术分析系统的得分与耦合度的空间分布特征。结果表明:长江中游城市群的36个城市的经济发展、城市化和社会保障水平的空间分布比较相似,三者间存在显著的正相关关系。但是,存在显著性的地区差异。36个城市生态环境得分均值很高,城市之间差异很小。从耦合度的空间分布来看,长江中游城市群明显存在3个高耦合度的聚集区域,即长株潭城市圈,武汉-南昌(含鄂州、黄石和九江)城市带和鄂北4市,即十堰、襄阳、宜昌和荆门。最后,36个城市之间耦合度的差异呈现逐年缩小的趋势。 相似文献
662.
针对新能源并网容量不断增加,大规模新能源接入电网时无功电压控制困难的问题,通过研究在新能源大出力方式下系统电压水平、电压波动及严重故障时电压失稳情况,提出了动态无功补偿、低压无功补偿配置方案。研究结果表明提出的无功配置方案适用于宁夏电网新能源场站和新能源汇集站的动态无功补偿,已纳入宁夏“十三五”电网滚动规划,对于保障宁夏电网安全稳定运行具有重要意义。 相似文献
663.
针对宁夏电网结构及运行特性发生的变化及日益严重的短路电流超标问题,本文基于宁夏电网“十三五”规划,提出将宁夏电网分为4个区域的供电分区方案。从电力电量平衡、短路电流水平、安全稳定等方面进行分析,并结合短路电流和动态电压稳定裕度指标对分区方案进行最大供电能力研究。结果表明:分区方案合理、有效,可为宁夏“十三五”电网规划提供了技术支持和决策参考。 相似文献
664.
665.
垃圾渗滤液中典型内分泌干扰物质(EDCs)细胞毒性分析 总被引:1,自引:0,他引:1
垃圾渗滤液的人类健康风险评估日益受到人们重视,也成为研究热点。本文采用一种新型高级氧化技术UV-Fenton处理渗滤液,并用人体乳腺癌细胞(MCF-7)评估处理过程中渗滤液原液以及渗滤液中典型内分泌干扰物质(EDCs)的细胞毒性,对垃圾渗滤液中EDCs的细胞毒性和变化规律进行了研究。结果表明渗滤液中的邻苯二甲酸二丁酯(DBP)、双酚A(BPA)、壬基酚(NP)是产生细胞毒性的主要物质,其毒性大小为DBPBPANP。在同样的氧化降解过程中显示出不同毒性变化规律,通过GC-MS分析,结果显示UV-Fenton过程中产生了大量的中间产物,这也是引起毒性变化的主要原因。实验结果也说明垃圾渗滤液细胞毒性可以通过UV-Fenton过程有效去除。 相似文献
666.
The hexadecyltrimethylammonium bromide (HDTMAB) immobilized hollow mesoporous silica spheres were prepared for the efficient removal of perfluorooctane sulfonate (PFOS) from aqueous solution. Besides the traditional sorption behavior including sorption kinetics as well as effect of solution pH and temperature, the effect of increasing volume which simulated the natural river where the rate of solute and solvent was relatively constant and solution volume was always changing was investigated. The result indicated that the residual PFOS concentrations in aqueous phase decreased with increasing solution pH and ionic strength, whereas they increased with increasing temperature. The HDTMAB immobilized material still maintained high efficiency after increasing volume, that is, the removal kept more than 99% after the treatment when the initial PFOS concentration was 1 mg L?1. The uptake behavior and morphology of spheres which was characterized by transmission electron microscopy (TEM) revealed that the additional HDTMAB and mesoporous shell were responsible for the enhanced sorption of PFOS. It was concluded that electrostatic interaction and Ca-bridge role played an important role in the sorption of PFOS on the mesoporous SiO2 hollow spheres, whereas, hydrophobic interaction contributed to the nice sorption performance of PFOS on the HDTMAB immobilized sorbent. 相似文献
667.
青萍(Lemna minor L.)对氮磷的吸收特征 总被引:1,自引:0,他引:1
以西部地区优势浮萍品种青萍为实验对象,研究了青萍对不同浓度硝态氮和磷酸盐的吸收特征。结果表明,硝态氮浓度在1~10 mg/L范围内,青萍对硝态氮有较好的吸收效果,M-M方程可以较好地描述硝态氮浓度与青萍对硝态氮的吸收速率之间的关系,通过M-M方程拟合得到青萍对硝态氮的最大吸收速率为0.1167 mg/(g FW.h),亲和力常数为6.9274。磷酸盐浓度在0.1~1.0 mg/L范围内,青萍对磷酸盐也有较好的吸收效果,二次多项式回归可以较好地描述青萍吸收速率与磷酸盐浓度的关系,回归方程得到青萍对磷酸盐的最大吸收速率为0.0193 mg/(g FW.h),对应磷酸盐浓度为0.6 mg/L。 相似文献
668.
669.
Pentachlorobenzene (PeCB) in simulated flue gas was destructed by a commercial V2O5-WO3/TiO2 catalyst in this study. The effects of reaction temperature, oxygen concentration, space velocity and some co-existing pollutants on PeCB conversion were investigated. Furthermore, a possible mechanism for the oxidation of PeCB over the vanadium oxide on the catalysts was proposed. Results show that the increase of gas hourly space velocity (GHSV) and the decrease of operating temperature both resulted in the decrease of PeCB removal over the catalyst, while the effect of the oxygen content in the range of 5-20% (v/v) on PeCB conversion was negligible. PeCB decomposition could be obviously affected by the denitration reactions under the conditions because of the positive effect of NO but negative effect of NH3. The introduction of SO2 caused the catalyst poisoning, probably due to the sulfur-containing species formed and deposited on the catalyst surface. The PeCB molecules were first adsorbed on the catalyst surface, and then oxidized into the non-aromatic acyclic intermediates, low chlorinated aromatics and maleic anhydride. 相似文献
670.
In recent years, increasing attention has been paid to the trace-level contamination of pharmaceuticals in the water environment all over the world. Considering a large number of pharmaceuticals used, it is crucial to establish a priority list of pharmaceuticals that should be monitored and/or treated first. In the present study, we developed a ranking system based on the pharmaceutical consumption, removal performance in the wastewater treatment plants (WWTPs) and potential ecological effects, and applied to the situation of China. 39 pharmaceuticals, which had available consumption data and also been reported previously in the WWTPs of China, were selected as candidate pharmaceuticals. Among them, seventeen pharmaceuticals were considered as priority pharmaceuticals, out of which, erythromycin, diclofenac acid and ibuprofen, had the high priority. Compared with other literatures, we found that some pharmaceuticals given concerns to globally should also be included in the priority list in China; while some pharmaceuticals, not mentioned in other literatures, such as cefalexin, ketoconazole, should be also given prior consideration in China. Among all the therapeutic classes, antibiotics, which were grossly abused in China, contributed the most to the priority pharmaceuticals. However, priority antibiotics accounted for only 32% of candidate antibiotics, while 71% and 100% of the candidate anti-inflammatory and antilipidemic respectively were identified as the priority pharmaceuticals, indicating that antibiotics might be overanxiously considered in the previous studies on their behaviors in the WWTPs of China. 相似文献