全文获取类型
收费全文 | 180篇 |
免费 | 1篇 |
国内免费 | 2篇 |
专业分类
化学 | 121篇 |
力学 | 5篇 |
数学 | 15篇 |
物理学 | 42篇 |
出版年
2023年 | 5篇 |
2021年 | 4篇 |
2020年 | 4篇 |
2019年 | 4篇 |
2018年 | 2篇 |
2017年 | 3篇 |
2016年 | 4篇 |
2015年 | 6篇 |
2014年 | 6篇 |
2013年 | 11篇 |
2012年 | 7篇 |
2011年 | 18篇 |
2010年 | 10篇 |
2009年 | 16篇 |
2008年 | 20篇 |
2007年 | 13篇 |
2006年 | 20篇 |
2005年 | 6篇 |
2004年 | 5篇 |
2003年 | 2篇 |
2002年 | 4篇 |
2001年 | 4篇 |
2000年 | 3篇 |
1995年 | 1篇 |
1993年 | 1篇 |
1992年 | 1篇 |
1990年 | 1篇 |
1987年 | 1篇 |
1981年 | 1篇 |
排序方式: 共有183条查询结果,搜索用时 31 毫秒
81.
Hydrogen fluoride analyzer for gases and aerosols 总被引:1,自引:0,他引:1
Many fire suppression agents are currently used, and the replacement candidates for these agents contain fluorine atoms. When these agents are used to extinguish a fire, large quantities of hydrogen fluoride gas can be produced from the thermal degradation of fluorinated organic compounds. A real-time analyzer has been developed to measure exposure levels of hydrogen fluoride gas and aerosols during fire suppression tests. A vacuum pump pulls air through a continuous denuder, where the toxic gas and aerosols are extracted from the air into an aqueous trapping solution. The trapping solution then passes through a flow cell, where a fluoride ion-selective electrode measures the fluoride ion concentration. A solenoid pump moves the trapping solution and calibration standards through the analyzer. Once calibrated, the analyzer can generate a concentration profile of hydrogen fluoride versus time. This hydrogen fluoride analyzer is portable and can be calibrated in about 5 min. It provides rapid response to hydrogen fluoride gas and aerosols, over a detection range from 1 to 5000 mg/m3. 相似文献
82.
Dr. Sailin Liu Dr. Jitraporn Vongsvivut Yanyan Wang Ruizhi Zhang Dr. Fuhua Yang Dr. Shilin Zhang Prof. Kenneth Davey Dr. Jianfeng Mao Prof. Zaiping Guo 《Angewandte Chemie (International ed. in English)》2023,62(4):e202215600
Zinc metal battery (ZMB) is promising as the next generation of energy storage system, but challenges relating to dendrites and corrosion of the zinc anode are restricting its practical application. Here, to stabilize Zn anode, we report a controlled electrolytic method for a monolithic solid-electrolyte interphase (SEI) via a high dipole moment solvent dimethyl methylphosphonate (DMMP). The DMMP-based electrolytes can generate a homogeneous and robust phosphate SEI (Zn3(PO4)2 and ZnP2O6). Benefiting from the protecting impact of this in situ monolithic SEI, the zinc electrode exhibits long-term cycling of 4700 h and a high Coulombic efficiency 99.89 % in Zn|Zn and Zn|Cu cell, respectively. The full V2O5|Zn battery with DMMP-H2O hybrid electrolyte exhibits a high capacity retention of 82.2 % following 4000 cycles under 5 A g−1. The first success in constructing the monolithic phosphate SEI will open a new avenue in electrolyte design for highly reversible and stable Zn metal anodes. 相似文献
83.
《Analytical letters》2012,45(14):2257-2266
Fire accelerants such as gasoline, kerosene, and diesel have commonly been used in arson cases. Improved analytical methods involving the extraction of fire accelerants are necessary to increase sample yield and to reduce the number of uncertain findings. In this study, an analytical method based on headspace single drop microextraction (HS-SDME) followed by gas chromatography–flame ionization detection (GC-FID) has been developed for the analysis of simulated fire debris samples. Curtain fabric was used as the sample matrix. The optimized conditions were 2.5 μL benzyl alcohol microdrop exposed for 20 min to the headspace of a 10 mL aqueous sample containing accelerants placed in 15-mL sample vial and stirred at 1500 rpm. The extraction method was compared with the solvent extraction method using n-hexane for the determination of fire accelerants. The HS-SDME process is driven by the concentration difference of analytes between the aqueous phases containing the analyte and the organic phase constituting the microdrop of a solvent. The limit of detection of HS-SDME for kerosene was 1.5 μL. Overall, the HS-SDME coupled with GC-FID proved to be rapid, simple and sensitive and a good alternative method for the analysis of accelerants in fire debris samples. 相似文献
84.
The thermal and fire properties of PMMA modified with various loadings of melamine or zinc aluminum undecenoate LDH were evaluated using TGA, DTA and cone calorimetry. The additives were characterized by X-ray diffraction, TGA, FT-IR and elemental analysis. While the two additives are very effective with this polymer, a higher loading of melamine (30%) is required to reach a good reduction in PHRR (47%) relative to the pure polymer, while with the LDH, 10% loading is enough to obtain a similar reduction. The combinations of these additives in PMMA reveal that the time to PHRR and the amount of smoke produced are the key differences, with melamine increasing the first parameter and leading to less smoke production relative to LDH-rich PMMA systems at similar total additive loadings. Analysis of the residue shows that melamine is completely lost during combustion while the LDH forms ZnO and ZnAl2O4. 相似文献
85.
Marta Sacristán Anna A. Stec Marina Galià Virginia Cádiz 《Polymer Degradation and Stability》2010,95(7):1269-1190
The fire retardance and thermal stability of soybean-based copolymers reactively modified by copolymerization with trimethylsilylstyrene (SiST) and tris-(4-vinylphenylboroxine) (BST) have been compared with those prepared with equivalent amounts of the additive 1,3-diphenyl-1,1,3,3-tetramethyldisiloxane (SiAD) and tris-(phenylboroxine) (BAD) and with the heteroatom-free soybean-based copolymers. The best results are obtained for the boron-containing copolymers. The reactive or additive approach is a significant factor in terms of the level of fire retardance achieved. 相似文献
86.
This series investigates silicone composites with enhanced thermal behaviour for cable applications. Calcium and aluminium-based fillers introduced into silicone formulations were classified according to three categories: non-hydrated fillers such as CaCO3 (precipitated calcium carbonate and natural calcite) and wollastonite, water-releasing fillers such as calcium hydroxide, ATH, boehmite, and hydroxyl-functionalized fillers including alumina and mica. The fillers were first characterized in detail, and the thermal stability of their blends with silicone was recorded by thermogravimetric analyses. A discussion on various aspects of the filler morphology (size, microstructure, release profile with temperature) on the silicone stability is finally given. 相似文献
87.
B. Swoboda S. Buonomo E. Leroy J.M. Lopez Cuesta 《Polymer Degradation and Stability》2008,93(5):910-917
Flame retardant recycled PET blends containing PC and triphenyl phosphite (TPP) have been designed using the following sequential processing strategy: PET and PC are first melt blended with a transesterification catalyst, allowing the compatibilisation of the blend, before adding TPP. The presence of this last component was shown to stop the transesterification reaction between PET and PC, avoiding chain breaking. In addition, TPP acts as a chain extender of PET, allowing the average chain length to be increased. The optimized blends obtained present “V-0” UL94 rating due to a better thermal stability leading to low flammability and to the development of an important, stable and covering char layer, resulting in self-extinguishability and very low Heat Release Rates during combustion. 相似文献
88.
采用SEM、XRD、TGA等分析方法对高抗冲聚苯乙烯/有机蒙脱土(HIPS/OMMT)纳米复合材料在燃烧过程中形成的炭渣残余物结构特征进行了研究,包括炭层断面形态,片层结构及炭渣热稳定性等.结果表明复合材料在热释放速率峰值之后,形成了具有阻燃作用的炭层结构,其特征是在炭层表面形成了一层比较薄但密实的皮层,皮层之下是较厚的一层蜂窝层,这种"皮-窝"结构赋予炭层良好的阻隔热的作用,减缓了热分解过程.XRD分析还表明原有插层结构经过燃烧已破坏,在皮-窝炭层中都已消失,结合SEM观察结果,蒙脱土片层多以剥离的单片层无规分布,皮层和窝层中聚合物已基本烧蚀,只剩下片状的蒙脱土聚集在一起形成了一种纳米尺寸的网状结构并包含了一定量的分解温度很高的碳质物质,不仅形成了稳定的保护层,而且碳质物质的生成也降低了材料分解挥发速率.窝层含有大量尺寸较大的空穴结构,隔气效果不如皮层,但显著地增大了炭层的体积,整体上能起到较大的隔热作用.二者共同构筑的皮-窝炭层结构在复合材料的燃烧过程中起到了阻燃的作用. 相似文献
89.
90.
Emilia Villani Percy Igei Kaneshiro Paulo Eigi Miyagi 《Nonlinear Analysis: Theory, Methods & Applications》2006
This paper approaches the problem of analysing control strategies for Fire Safety Systems. The components of Fire Safety Systems present behaviours of different nature and therefore the use of a hybrid modelling formalism is necessary. Petri net is used to model the discrete dynamics. Algebraic and differential equations are used for the continuous one. In order to realistically evaluate the performance of Fire Safety Systems, failures and other uncertainties, such as people’s behaviour, should be included in the model. Due to the model complexity, results are obtained by Monte Carlo simulation. 相似文献