全文获取类型
收费全文 | 447篇 |
免费 | 53篇 |
国内免费 | 116篇 |
专业分类
安全科学 | 175篇 |
废物处理 | 3篇 |
环保管理 | 33篇 |
综合类 | 282篇 |
基础理论 | 37篇 |
污染及防治 | 29篇 |
评价与监测 | 38篇 |
社会与环境 | 1篇 |
灾害及防治 | 18篇 |
出版年
2024年 | 5篇 |
2023年 | 17篇 |
2022年 | 22篇 |
2021年 | 28篇 |
2020年 | 14篇 |
2019年 | 22篇 |
2018年 | 14篇 |
2017年 | 20篇 |
2016年 | 13篇 |
2015年 | 22篇 |
2014年 | 70篇 |
2013年 | 29篇 |
2012年 | 34篇 |
2011年 | 53篇 |
2010年 | 13篇 |
2009年 | 19篇 |
2008年 | 21篇 |
2007年 | 30篇 |
2006年 | 25篇 |
2005年 | 25篇 |
2004年 | 10篇 |
2003年 | 19篇 |
2002年 | 9篇 |
2001年 | 9篇 |
2000年 | 4篇 |
1999年 | 7篇 |
1998年 | 9篇 |
1997年 | 7篇 |
1996年 | 6篇 |
1995年 | 7篇 |
1994年 | 6篇 |
1993年 | 5篇 |
1992年 | 3篇 |
1991年 | 3篇 |
1990年 | 3篇 |
1989年 | 9篇 |
1988年 | 3篇 |
1987年 | 1篇 |
排序方式: 共有616条查询结果,搜索用时 437 毫秒
581.
582.
583.
朱季元 《特种设备安全技术》2007,(3):59-60
1 现有X射线成像的处理手段
射线成像检测有两种方式:一种是以胶片形式存贮的离线检测.例如:在锅炉压力容器检测中大量使用的X光照片。拍摄好的底片图像放在扫描仪中.通过图像扫描仪把底片图像扫描数字化成为数字图像,送入到计算机内,由计算机对数字图像进行调整、滤波、增强、压缩和识别等处理.改善图像的清晰度,通过人机对话对底片图像缺陷进行评估. 相似文献
584.
《中国安防产品信息》2006,(2):33-33
市场经济的快速发展,促进了市场产品的多元化和丰富性,充分的满足了消费者的需求。但同时,仿造、假冒产品也大量的出现,严重影响了消费者和用户的利益。尤其是那些关乎国计民生的特殊产品和物品,如铁路物资、医药产品及设备、枪支弹药等军用物资、液化气瓶等工业压力容器,一旦出现产品仿冒和不合格现象,将给社会和个人带来不可估量的损失。这些特殊物品的生产、流通、使用及维修,需要有安全、有效的防伪及追踪保障措施。 相似文献
585.
586.
垂序商陆叶细胞壁结合锰机制研究 总被引:1,自引:0,他引:1
垂序商陆是一种典型的锰超积累植物,细胞壁在其累积解毒锰的过程中起了一定的作用.通过细胞壁吸附实验,研究不同p H和不同锰浓度对细胞壁吸附锰的影响,并采用傅立叶红外光谱及同步辐射X-射线吸收光谱技术探讨了其吸附机制.结果表明,垂序商陆叶细胞壁吸附锰的最适p H值为5~6;其吸附行为可用Langmuir模型较好地描述(R2=0.978 5),并计算得其最大吸附量为62.50μmol·g-1.细胞壁上的羟基(—OH)和羰基(—CO)是结合锰的主要位点;锰周围第一配层为氧原子,其配位数为6.3,Mn—O键长为0.216 nm,细胞壁与锰主要以内配层模式相结合. 相似文献
587.
Arsenic (As) pollutants generated by human activities in karst areas flow into subterranean streams and contaminate groundwater easily because of the unique hydrogeological characteristics of karst areas. To elucidate the reaction mechanisms of arsenic in karst subterranean streams, physical-chemical analysis was conducted by an inductively coupled plasma mass spectrometer and an X-ray fluorescence spectrometer. The results show that inorganic species account for most of the total arsenic, whereas organic arsenic is not detected or occurs in infinitesimal amounts. As(III) accounts for 51.0% ± 9.9% of the total inorganic arsenic. Arsenic attenuation occurs and the attenuation rates of total As, As(III) and As(V) in the Lihu subterranean stream are 51%, 36% and 59%, respectively. To fully explain the main geochemical factors influencing arsenic attenuation, SPSS 13.0 and CANOCO 4.5 bundled with CanoDraw for Windows were used for simple statistical analysis and redundancy analysis (RDA). Eight main factors, i.e., sediment iron (SFe), sediment aluminum (SAI), sediment calcium (SCa), sediment organic matter (SOM), sediment manganese (SMn), water calcium (WCa^2+), water magnesium (WMg^2+), and water bicarbonate ion (WILCOX) were extracted from thirteen indicators. Their impacts on arsenic content rank as: SFe〉SCa〉WCa^2+〉SAl〉wHCO3^-〉SMn〉SOM〉WMg^2+. Of these factors, SFe, SAl, SCa, SOM, SMn, WMg^2+ and WCa&2+ promote arsenic attenuation, whereas WHCO3^- inhibits it. Further investigation revealed that the redox potential (Eh) and pH are adverse to arsenic removal. The dramatic distinction between karst and non-karst terrain is that calcium and bicarbonate are the primary factors influencing arsenic migration in karst areas due to the high calcium concentration and alkalinity of karst water. 相似文献
588.
Chemical looping combustion (CLC) of coal has gained increasing attention as a novel combustion technology for its advantages in CO2 capture. Sulfur evolution from coal causes great harm from either the CLC operational or environmental perspective. In this research, a combined MnFe2O4 oxygen carrier (OC) was synthesized and its reaction with a typical Chinese high sulfur coal, Liuzhi (LZ) bituminous coal, was performed in a thermogravimetric analyzer (TGA)-Fourier transform infrared (FT-IR) spectrometer. Evolution of sulfur species during reaction of LZ coal with MnFeaO40C was systematically investigated through experimental means combined with thermodynamic simulation. TGA-FTIR analysis of the LZ reaction with MnFe2O4 indicated MnFe2O4 exhibited the desired superior reactivity compared to the single reference oxides Mn304 or Fe203, and SO2 produced was mainly related to oxidization of H2S by MnFe2O4. Experimental analysis of the LZ coal reaction with MnFe2O4, including X-ray diffraction and X-ray photoelectron spectroscopy analysis, verified that the main reduced counterparts of MnFe2O4 were Fe304 and MnO, in good agreement with the related thermodynamic simulation. The obtained MnO was beneficial to stabilize the reduced MnFe2O4 and avoid serious sintering, although the oxygen in MnO was not fully utilized. Meanwhile, most sulfur present in LZ coal was converted to solid MnS during LZ reaction with MnFe2O4, which was further oxidized to MnSO4. Finally, the formation of both MnS and such manganese silicates as Mn2SiO4 and MnSiO3 should be addressed to ensure the full regeneration of the reduced MnFe2O4. 相似文献
589.
Caiyun Yan Ku-Fan Chen Chia-Hsiang Lai Shiau-Wu Lai Qing Chang Yen-Ping Peng 《环境科学学报(英文版)》2014,26(7):1505-1512
Microwave-induced nitrogen-doped titanate nanotubes(NTNTs) were characterized by transmission electron microscopy(TEM), X-ray diffraction(XRD), X-ray photoelectron spectroscopy(XPS), Fourier transform infrared spectroscopy(FT-IR), Zeta potential analysis,specific surface area(SBET), and UV-Visible spectroscopy. TEM results indicate that NTNTs retain a tubular structure with a crystalline multiwall and have a length of several hundred nanometers after nitrogen doping. XRD findings demonstrate that the crystalline structure of NTNTs was dominated by anatase, which is favored for photocatalytic application. The Ti-O-N linkage observed in the XPS N 1s spectrum is mainly responsible for narrowing the band gap and eventually enhancing the visible light photoactivity. FT-IR results demonstrated the existence of H3O+, which could be excited by photo-generated holes to form hydroxyl radicals and degrade environmental pollutants. After sintering at 350°C, the UV-Vis absorbance edges of NTNTs significantly shift to the visible-light region, which indicates N atom doping into the nanotubes. Photocatalytic degradation of Rhodamine B(RhB) via NTNTs show good efficiency, with pseudo first-order kinetic model rate constants of 3.7 × 10-3, 2.4 × 10-3and 8.0 × 10-4sec-1at pH 3, 7, and 11, respectively. 相似文献
590.