全文获取类型
收费全文 | 1176篇 |
免费 | 75篇 |
国内免费 | 382篇 |
专业分类
安全科学 | 100篇 |
废物处理 | 48篇 |
环保管理 | 102篇 |
综合类 | 686篇 |
基础理论 | 216篇 |
污染及防治 | 297篇 |
评价与监测 | 66篇 |
社会与环境 | 57篇 |
灾害及防治 | 61篇 |
出版年
2024年 | 3篇 |
2023年 | 22篇 |
2022年 | 68篇 |
2021年 | 47篇 |
2020年 | 34篇 |
2019年 | 33篇 |
2018年 | 49篇 |
2017年 | 39篇 |
2016年 | 52篇 |
2015年 | 50篇 |
2014年 | 75篇 |
2013年 | 97篇 |
2012年 | 69篇 |
2011年 | 91篇 |
2010年 | 77篇 |
2009年 | 76篇 |
2008年 | 74篇 |
2007年 | 50篇 |
2006年 | 71篇 |
2005年 | 60篇 |
2004年 | 37篇 |
2003年 | 59篇 |
2002年 | 75篇 |
2001年 | 64篇 |
2000年 | 36篇 |
1999年 | 38篇 |
1998年 | 53篇 |
1997年 | 29篇 |
1996年 | 27篇 |
1995年 | 15篇 |
1994年 | 24篇 |
1993年 | 14篇 |
1992年 | 11篇 |
1991年 | 4篇 |
1990年 | 3篇 |
1988年 | 2篇 |
1987年 | 2篇 |
1984年 | 1篇 |
1983年 | 2篇 |
排序方式: 共有1633条查询结果,搜索用时 15 毫秒
131.
Calcium carbonate (CaCO3) application is widely used to ameliorate soil acidification. To counteract soil and bacterial community response to CaCO3 application in an acidic paddy soil in southern China, a field experiment was conducted with four different dosages of CaCO3 addition, 0, 2.25, 4.5 and 7.5?tons/ha, respectively. After one seasonal growth of rice, soil physicochemical properties, soil respiration and bacterial communities were investigated. Results showed that soil pH increased accordingly with increasing dose of CaCO3 addition, and 7.5?tons/ha addition increased soil pH to neutral condition. Moderate dose of CaCO3 application (4.5?tons/ha) significantly increased soil dissolved organic carbon (DOC) and dissolved organic nitrogen (DON) content, enhanced soil respiration, while the excessive CaCO3 application (7.5?tons/ha) decreased these soil properties. High-throughput sequencing results illustrated that moderate dose of CaCO3 application increased the richness and alpha diversity of soil bacterial community. Compared with control, the relative abundance of Anaerolineaceae family belonging to Chloroflexi phylum increased by 38.7%, 35.4% and 24.5% under 2.25, 4.5 and 7.5?tons/ha treatments, respectively. Redundancy analysis (RDA) showed that soil pH was the most important factor shaping soil bacterial community. The results of this study suggest that proper dose of CaCO3 additions to acid paddy soil in southern China could have positive effects on soil properties and bacterial community. 相似文献
132.
河北省典型污灌区农田镉污染特征及环境风险评价 总被引:6,自引:0,他引:6
以河北省石家庄市典型历史污灌区农田为研究对象,对污灌区内土壤和小麦、玉米植株内Cd的含量进行分析,评价污灌区农田Cd污染程度、潜在生态风险和潜在健康风险.结果表明,上游污灌区和中下游污灌区土壤表层Cd含量分别为ND~3.88、0.10~2.30 mg·kg~(-1),明显高于清灌区(0.13~0.23 mg·kg~(-1))及河北土壤背景值(0.094 mg·kg~(-1)),超农用地土壤污染风险筛选值(0.3 mg·kg~(-1))点位分别达42.9%和35.2%;小麦和玉米籽粒平均Cd含量均未超标,小麦籽粒富集浓度高于玉米,污灌区小麦和玉米籽粒已出现明显累积现象.潜在生态风险表明上游污灌区和中下游污灌区表层土壤基本处于轻度~中度风险,部分区域生态风险较高~极高.健康风险评价结果表明Cd通过皮肤、呼吸、经口摄入暴露途径对人体健康造成的风险在可接受范围内.研究结果为污灌区农田土壤的安全利用和管理决策依据,并为开展农田土壤修复工程提供科学参考. 相似文献
133.
Rongshan Wu Xiaoming Song Yingchen Bai Jie Chen Qian Zhao Shuo Liu Hongbing Xu Tong Wang Baihuan Feng Yi Zhang Liuju Zhong Xuemei Wang Fengchang Wu Wei Huang 《环境科学学报(英文版)》2018,30(9):67-75
With rapid economic development and urbanization in recent decades, China has experienced the worsening of ambient air quality. For better air quality management to protect human health, Chinese government revised national ambient air quality standards(NAAQS) for particulate matter(PM) in 2012(GB3095-2012). To assess the effectiveness of current NAAQS for PM on public health in Chinese population, we conducted a metaanalysis on published studies examining the mortality risk of short-term exposure to PM with aerodynamic diameters less than 10 and 2.5 μm(PM_(10) and PM_(2.5)) in China. The reported24-hour concentrations of PM_(10) and PM_(2.5) in studies ranged from 43.5 to 150.1 μg/m~3 and 37.5 to 176.7 μg/m~3. In the pooled excess, mortality risk estimates of short-term exposure to PM.In specific, per 10 μg/m~3 increase in PM_(10), we observed increases of 0.40%(95%CI: 0.33%,0.47%), 0.57%(95%CI: 0.44%, 0.70%) and 0.49%(95%CI: 0.40%, 0.58%) in total, respiratory and cardiovascular mortality, per 10 μg/m~3 increase in PM_(2.5), we observed increases of 0.51%(95%CI: 0.38%, 0.63%), 0.62%(95%CI: 0.52%, 0.73%) and 0.75%(95%CI: 0.54%, 0.95%) in total,respiratory and cardiovascular mortality. Finally, we derived 125 μg/m~3 for PM_(10) and 62.5 μg/m~3 for PM_(2.5) as 24-hour recommendation values based on the pooled estimates. Our results indicated that current Chinese NAAQS for PM could be sufficient in mitigating the excess mortality risk from short-term exposure to ambient PM. However, future research on longterm exposure cohort studies in Chinese population is also essential in revising annual averages for PM in Chinese NAAQS. 相似文献
134.
目的提高铝硅涂层的抗氧化性能。方法采用料浆法在DZ417G定向凝固镍基高温合金叶片的燃气流道表面制备铝硅防护涂层,通过扫描电子显微镜(SEM)分析不同条件下进行渗后扩散的铝硅涂层表面显微组织形貌和截面显微组织形貌。结果无保护气氛下进行渗后扩散处理的铝硅涂层,在扩散过程中就已经发生了氧化,氧化过程首先形成多孔非致密结构的θ-Al_2O_3相,随着氧化过程的进行,θ-Al_2O_3相逐渐转变成致密结构的α-Al_2O_3相,从而起到真正的抗氧化作用。结论铝硅涂层中的Al元素提前被消耗,对铝硅涂层的使用寿命存在一定影响,因而渗后扩散须保证在真空条件下或有保护气氛条件下进行,使叶片表面渗后的铝浓度达到一定的要求,从而在使用过程中可以生成致密结构的α-Al_2O_3相,起到抗氧化作用,提高叶片的使用寿命。 相似文献
135.
136.
为实现水资源的循环利用与国民经济的可持续发展,必须对工业废水进行处理。在过去的几十年中,工业废水的任意排放给水资源环境和人民的身体健康带来了巨大的危害,为了杜绝这种现象的再次出现,本文对工业废水的处理方法做了如下的探讨。 相似文献
137.
To find a simple and economical way for treating the domestic wastewater in small counties and towns, a process combining chemically enhanced primary treatment and a trickling filter (CEPT-TF, representing the physical and biological effects) was constructed and operated in laboratory conditions. The characteristic behaviors of dissolved organic matter in raw wastewater and effluents were examined during steady-state operation. Experimental results showed that the process of CEPT and TF in series was beneficial for the removal of hydrophobic and hydrophilic organics. Specially, the hydrophobic and aromatic materials could be preferentially removed in the CEPT unit, and the hydrophilic fraction in the TF. Structural changes of the organic fractions during the operation of the different units were also characterized via spectrum analysis. 相似文献
138.
139.
140.
钢渣湿法脱硫试验研究 总被引:3,自引:2,他引:3
以某厂钢渣为吸收剂,以旋流板塔为吸收器,对湿法脱硫进行了试验研究。通过分析钢渣脱硫前后的化学成分变化,以及试验脱硫率随反应过程的变化,提出了钢渣湿法脱硫的反应机理。同时,试验研究了液气比、进气SO_2浓度、浆液浓度等主要参数对脱硫率的影响,以及加添加剂的效果。试验结果表明,通过合理的设计和适当的操作,可使钢渣湿法应用于中低脱硫率(50%~70%)的场合,以取得综合治理、以废治废的效果。 相似文献