全文获取类型
收费全文 | 5285篇 |
免费 | 544篇 |
国内免费 | 1927篇 |
专业分类
安全科学 | 538篇 |
废物处理 | 256篇 |
环保管理 | 462篇 |
综合类 | 3498篇 |
基础理论 | 864篇 |
环境理论 | 1篇 |
污染及防治 | 1217篇 |
评价与监测 | 325篇 |
社会与环境 | 340篇 |
灾害及防治 | 255篇 |
出版年
2024年 | 23篇 |
2023年 | 139篇 |
2022年 | 311篇 |
2021年 | 337篇 |
2020年 | 326篇 |
2019年 | 229篇 |
2018年 | 270篇 |
2017年 | 304篇 |
2016年 | 233篇 |
2015年 | 326篇 |
2014年 | 442篇 |
2013年 | 480篇 |
2012年 | 467篇 |
2011年 | 454篇 |
2010年 | 355篇 |
2009年 | 341篇 |
2008年 | 399篇 |
2007年 | 321篇 |
2006年 | 291篇 |
2005年 | 205篇 |
2004年 | 174篇 |
2003年 | 197篇 |
2002年 | 187篇 |
2001年 | 151篇 |
2000年 | 160篇 |
1999年 | 115篇 |
1998年 | 88篇 |
1997年 | 79篇 |
1996年 | 78篇 |
1995年 | 61篇 |
1994年 | 52篇 |
1993年 | 35篇 |
1992年 | 43篇 |
1991年 | 16篇 |
1990年 | 16篇 |
1989年 | 9篇 |
1988年 | 10篇 |
1987年 | 6篇 |
1986年 | 3篇 |
1984年 | 3篇 |
1983年 | 4篇 |
1982年 | 4篇 |
1981年 | 2篇 |
1979年 | 2篇 |
1978年 | 1篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1973年 | 1篇 |
1972年 | 2篇 |
1971年 | 1篇 |
排序方式: 共有7756条查询结果,搜索用时 897 毫秒
451.
创意产业集聚区在促进创意产业发展、优化城市空间结构等方面具有重要意义,而以满足创意阶层特征和需求的创意产业集聚区内部公共空间规划的研究相对较少。从创意阶层交往的“心理-行为-空间”这一互动视角出发,选取南京具有代表性的“创意东8区”为研究对象,通过调查问卷、深入访谈和实地观察对创意阶层的“交往心理-交往行为-交往空间”进行了研究。在此基础上,从人口交往空间、中心交往空间、节点交往空间、道路交往空间等方面提出符合创意阶层心理和行为特征,并能促进交往产生的外部交往空间规划设计建议。 相似文献
452.
建立了利用组合单标多点校正和英蓝超滤单元的离子色谱法测定地表水中F-、C1-、NO3-、S0424—4-种离子的方法,方法操作简便,灵敏度高,线性范围广,抗干扰能力强,可同时快速测定不同数量级浓度的离子,降低了配置标准品和样品前处理的复杂性,减少了因前处理带来的干扰。 相似文献
453.
We collected three ornithogenic coral sand sedimentary profiles from Jinyin Island, Jinqing Island and Guangjin Island of Yongle archipelago, South China Sea and reconstructed the deposition flux of anthropogenic Hg over the past 700 years in the study area. On the whole, the anthropogenic Hg flux is relatively low; it remained at a low level before the Industrial Revolution with a small peak at about 1450-1550 AD, which may record the enhanced metallurgy activity in Ming Dynasty of China. During the 20th century, the deposition flux of anthropogenic Hg increased rapidly, but two troughs occurred during the periods around 1940s and 1970s, corresponding to the economic depression caused by World War II, Civil War in China (1945-1949), and the Culture Revolution (1966-1976) in China. Since the 1970s the deposition flux of anthropogenic Hg has been persistently increasing, apparently the result of fast economic development in East and Southeast Asia countries around South China Sea. 相似文献
454.
Liu YH Xie R Guo YR Zhu GN Tang FB 《Journal of environmental science and health. Part. B》2012,47(5):475-483
The effectiveness of homologous and heterologous formats in a nanocolloidal gold-based immunoassay for pesticide residue determination was investigated. Parathion, one of the most toxic organophosphorus pesticides, was used as the target analyte. One-step homologous and heterologous test strips based on a nanocolloidal gold-labeled monoclonal antibody were developed for the rapid detection of parathion residues. The results showed that the heterologous format was more effective than the homologous format, being more sensitive, more specific to parathion and more tolerant of matrix interferences. The best competitive hapten was found to have a moderate heterology and the opposite electronic distribution to the immunizing hapten. The detection limits for parathion using the preferred heterologous strip were 1 μg/L in water samples and 5 μg/kg in soil and food samples. 相似文献
455.
Removal of genotoxicity in chlorinated secondary effluent of a domestic wastewater treatment plant during dechlorination 总被引:1,自引:0,他引:1
Wu QY Li Y Hu HY Ding YN Huang H Zhao FY 《Environmental science and pollution research international》2012,19(1):1-7
Purpose
Dechlorination with tetravalent sulfur is widely used in wastewater treatment processes after chlorination. Dechlorination can remove certain genotoxic disinfection by-products (DBPs). However, the reactions occurring during dechlorination of chlorinated secondary effluent and their genotoxic chemicals are still very complex, and the related genotoxicity changes remain unknown. Therefore, the effects of dechlorination on genotoxicity in secondary effluent and its fractions and typical genotoxic chemical after chlorination were evaluated. 相似文献456.
Li Y Tang J Yu X Xu X Cheng H Wang S 《Environmental science and pollution research international》2012,19(6):2329-2343
Introduction
Trends in precipitation pH and conductivity during 1992?C2009, and in ionic compositions from January 2007 to June 2009, are reported from Lushan Mountain, one of the highest mountains in mid-east China. Annual mean pH was in the range of 4.35?C5.01 and showed a statistically very significant (P?0.01) decreasing trend with time. Annual mean conductivity showed a statistically significant (P?0.05) increasing trend, although this was not the case for non-H conductivity. Increasing rainwater acidity was mainly caused by increasing amounts of acid substances entering the rain. The trends in precipitation pH and conductivity were directly associated with energy consumption.Results and discussions
Over the period of study, Lushan Mountain received more rainfall in spring and summer. The pH values varied seasonally with winter minima. The winter multiyear seasonal mean pH was 4.35. The corresponding summer value was 4.88. SO 4 2? and NO 3 ? were the main anions, and NH 4 + and Ca2+ the main cations. The anion to cation ratio was 0.8?C1.0, and that of [SO 4 2? ] to [NO 3 ? ] was 2.4-3.0, much lower than that of the 1980s. However, sulfuric acid was still the main acid present. The ratio of [NH 4 + ] to [Ca2+] was about 1.0, suggesting that these two alkaline substances provided close acid neutralizing capacity. The ratio of [Cl?] to [Na+] was about 0.67, somewhat lower than that of natural precipitation.Conclusions
Ionic composition varied seasonally and was closely correlated to the amounts of rainfall and pollution. Trajectory analyses showed that the trajectories to Lushan Mountain could be classified in six clusters and trajectories originating from the South Sea and the areas surrounding Lushan Mountain had the greatest impacts on precipitation chemistry. 相似文献457.
Changwei Hu Yuxiong Ou Dayi Zhang Hui Zhang Cheng Yan Yongjun Zhao Zheng Zheng 《Environmental science and pollution research international》2012,19(9):4168-4175
The Waigang River, a major tributary of the Qinhuai River system, has suffered from long-standing pollution because of lack of management. Restoration was commenced in April 2006 to reduce pollutants and improve water quality. Four ecological areas and ten surface carriers were constructed for the culture of plants (mainly water hyacinth (Eichhornia crassipes) and ryegrass (Lolium perenne L.)) for phytoremediation. Chemical oxygen demand (COD), total suspended solids (TSS), total phosphorus, total nitrogen (TN), ammonia?Cnitrogen (NH3?CN), water transparency, and variations in phytoplankton population were investigated to evaluate the effects of restoration. Over 36?months, TSS, COD, TN, and NH3?CN levels decreased by 91.1, 55.3, 91.5, and 86.5?%, respectively. Transparency increased from 25?cm in 2006 to 165?cm in 2009. Improvements in water quality significantly enhanced the diversity of phytoplankton, which were harmed by pollution stress. Our results show that the water hyacinth and ryegrass cultured in the ecological areas and the surface carriers can be used to restore other heavily polluted rivers with conditions similar to those of the Waigang River, especially in the initial stages of restoration. 相似文献
458.
Liang B Yao Q Cheng H Gao S Kong F Cui D Guo Y Ren N Wang A 《Environmental science and pollution research international》2012,19(5):1385-1391
Purpose
With the aim of enhanced degradation of azo dye alizarin yellow R (AY) and further removal of the low-strength recalcitrant matter (LsRM) of the secondary effluent as much as possible, our research focused on the combination of aerobic bio-contact oxidation (ABO) with iron/carbon microelectrolysis (ICME) process.Materials and methods
The combined ABO (with effective volume of 2.4?l) and ICME (with effectively volume of 0.4?l) process were studied with relatively short hydraulic retention time (HRT) of 4 or 6?h.Results
At the HRT of 6?h with the reflux ratio of 1 and 2, the AY degradation efficiency in the final effluent was >96.5%, and the total organic carbon (TOC) removal efficiency were 69.86% and 79.44%, respectively. At the HRT of 4?h and the reflux ratio of 2, TOC removal efficiency and AY degradation efficiency were 73.94% and 94.89%, respectively. The ICME process obviously enhanced the total AY removal and the generated micromolecule acids and aldehydes then that wastewater backflow to the ABO where they were further biodegraded.Conclusion
The present research might provide the potential options for the advanced treatment azo dyes wastewater with short HRT and acceptable running costs. 相似文献459.
在比较了不同基质脱氮效率的基础上,认为基质作为人工湿地的重要组成部分,在为植物和微生物提供生长介质的同时,也能通过沉淀、过滤和吸附等作用直接去除污染物质,其中基质的类型、级配等因素会影响基质作用的发挥;不同基质对脱氮性能存在较大差异,沸石和蛭石是目前研究中脱氮效率较高的两种基质。在归纳了脱氮机制和影响因素的基础上,认为不同基质由于脱氮机制不同,脱氮性能和脱氮效率也存在较大差异;人工湿地基质所有理化性状都可能影响到它对污水的脱氮效率。最后,对今后的相关研究方向进行了展望。 相似文献
460.
将磷钨酸、甲醛气体负载于介孔分子筛SBA-15中制备脱氮吸附剂,其中SBA-15、磷钨酸、甲醛的质量比为10∶7∶3.以喹啉、吲哚和咔唑为目标氮化物,二甲苯及二甲苯和十二烷的混合液为溶剂配制模拟含氮油,考察了反应温度、氮化物类型对脱氮反应速率的影响以及磷钨酸、甲醛的脱氮机制.结果表明,磷钨酸可以有效脱除碱性氮化物和低浓度非碱性氮化物,甲醛能强化吸附剂对非碱性氮化物的选择性.在70℃、脱氮吸附剂与高浓度模拟含氮油质量比为2.0∶30.0的条件下,模拟含氮油中的氮化物在90 min内可以被深度脱除.磷钨酸对碱性氮化物的脱除机制为磷钨酸和碱性氮化物间的配合作用和酸碱反应,磷钨酸对非碱性氮化物的脱除机制为氮化物和甲醛在酸催化下缩合反应生成聚合物.反应吸附剂再生回用后的脱氮能力随氮化物碱性的增强而减弱. 相似文献