首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   203篇
  免费   7篇
  国内免费   8篇
化学   146篇
晶体学   1篇
力学   13篇
数学   6篇
物理学   52篇
  2023年   3篇
  2022年   6篇
  2021年   7篇
  2020年   6篇
  2019年   3篇
  2018年   2篇
  2017年   3篇
  2016年   13篇
  2015年   7篇
  2014年   7篇
  2013年   13篇
  2012年   8篇
  2011年   23篇
  2010年   13篇
  2009年   10篇
  2008年   25篇
  2007年   11篇
  2006年   11篇
  2005年   5篇
  2004年   6篇
  2003年   6篇
  2002年   5篇
  2001年   5篇
  2000年   2篇
  1998年   4篇
  1997年   3篇
  1996年   3篇
  1995年   1篇
  1994年   2篇
  1993年   2篇
  1992年   2篇
  1949年   1篇
排序方式: 共有218条查询结果,搜索用时 15 毫秒
51.
Many MRI contrast agents formed with the parahydrogen-induced polarization (PHIP) technique exhibit biocompatible profiles. In the context of respiratory imaging with inhalable molecular contrast agents, the development of nonflammable contrast agents would nonetheless be highly beneficial for the biomedical translation of this sensitive, high-throughput and affordable hyperpolarization technique. To this end, we assess the hydrogenation kinetics, the polarization levels and the lifetimes of PHIP hyperpolarized products (acids, ethers and esters) at various degrees of fluorine substitution. The results highlight important trends as a function of molecular structure that are instrumental for the design of new, safe contrast agents for in vivo imaging applications of the PHIP technique, with an emphasis on the highly volatile group of ethers used as inhalable anesthetics.  相似文献   
52.
The environment-friendly bacterial strains are used for wastewater treatment due to their high degrading capability and cost-effectiveness. In the present study, we isolated, identified, characterized, and optimized culture condition ( Temperature 35 °C for both, time up to 96 h, pH 7 and 7.5 respectively) of two dye degrading bacteria from industrial effluents. Morphological, biochemical, and molecular identification confirmed those strains as Bacillus pseudomycoides and Acinetobacter haemolyticus. Spectrophotometric methods were used to investigate the dye degradation(single and mixed dye) capability of these two bacteria. These strains were the potential for degrading methylene green (MG), basic violet (BV) and acid blue (AB) dyes. In case of MG + BV, B. pseudomycoides, and A. haemolyticus showed a degradation rate of 74% and 75%, respectively. While degradation was found 75% and 82% for MG + AB combination, 73% and 73% for AB + BV combination, and 80% and 82% for MG + BV + AB combination respectively. Azoreductase enzymes from bacteria are essential for breaking down the azo bond in textile azo dyes. In molecular docking, the binding energy of three docking complexes (protein and MG, protein and BV, protein and AB) were ?6.3, ?6.6, and ?6.8 Kcal/mol, respectively. The binding stability of the docked complexes was ensured by the root mean square deviations (RMSD), solvent accessible surface area (SASA), radius of gyration (Rg) and hydrogen bond in a molecular dynamics simulation study, indicating strong and stable binding. This study revealed that both B. pseudomycoides and A. haemolyticus could decolorize single and mixed dyes efficiently. As a result, both the strains could be used in further research to apply their potentiality in large-scale dye degradation in the future.  相似文献   
53.
54.
Textile is one of the main components in the municipal waste which is to be diverted from landfill for material and energy recovery. As an initial investigation for energy recovery from textile residues, the combustion of cotton fabrics with a minor fraction of polyester was investigated in a packed bed combustor for air flow rates ranging from 117 to 1638 kg/m2 h (0.027–0.371 m/s). Tests were also carried out in order to evaluate the co-combustion of textile residues with two segregated waste materials: waste wood and cardboard.

Textile residues showed different combustion characteristics when compared to typical waste materials at low air flow rates below 819 kg/m2 h (0.186 m/s). The ignition front propagated fast along the air channels randomly formed between packed textile particles while leaving a large amount of unignited material above. This resulted in irregular behaviour of the temperature profile, ignition rate and the percentage of weight loss in the ignition propagation stage. A slow smouldering burn-out stage followed the ignition propagation stage. At air flow rates of 1200–1600 kg/m2 h (0.272–0.363 m/s), the bed had a maximum burning rate of about 240 kg/m2 h consuming most of the combustibles in the ignition propagation stage. More uniform combustion with an increased burning rate was achieved when textile residues were co-burned with cardboard that had a similar bulk density.  相似文献   

55.
In order to improve textile fabric abrasion resistance, in this work a SiOxCyHz thin film was realized by low pressure plasma chemical vapour deposition (PCVD) at room temperature, using hexamethyldisiloxane (HMDSO) as precursor compound. To test changes in the performance properties of the surface finished samples as a function of the type of the substrate, the deposition was carried out on different textile fabrics. The polymerization processes were followed by weight measurements of textile fabrics. It was found that, after PCVD, a significantly lower fabric weight loss was observed on treated samples after rubbing than on the untreated samples. The morphology, elemental composition and type of chemical bonding present in the film applied on textile fabrics were also investigated using electron scanning microscopy (SEM), energy dispersive X-ray (EDX) and infrared spectroscopy techniques (FT-IR (ATR)). The results showed a substantial enhancement of wear resistance for the surfaces modified with the presented process, while tensile and tearing strength were adversely affected.  相似文献   
56.
Water scarcity and pollution rank equal to climate change as the most urgent environmental turmoil for the 21st century. To date, the percolation of textile effluents into the waterways and aquifer systems, remain an intricate conundrum abroad the nations. With the renaissance of activated carbon, there has been a steadily growing interest in the research field. Recently, the adoption of titanium dioxide, a prestigious advanced photo-catalyst which formulates the new growing branch of activated carbon composites for enhancement of adsorption rate and discoloration capacity, has attracted stern consideration and supports worldwide. Confirming the assertion, this paper presents a state of art review of titanium dioxide/activated carbon composites technology, its fundamental background studies, and environmental implications. Moreover, its major challenges together with the future expectation are summarized and discussed. Conclusively, the expanding of activated carbons composites material represents a potentially viable and powerful tool, leading to the plausible improvement of environmental conservation.  相似文献   
57.
SPME-GC/MS在纺织品挥发性有害物质测定中的应用   总被引:5,自引:0,他引:5  
建立了纺织品挥发性有害物质的测定方法,试样剪碎后置于体积分数为5%的甲醇的饱和NaCl溶液中,(40±1)℃超声处理10min,而后采用顶空固相微萃取和色质联用技术(HS SPME GC/MS)对目标化合物进行了测定,方法给出了相应的检测限量和适用范围,对几种主要的干洗剂检测限量均低于0.005mg/kg,回收率在90.6%~108.7%之间。  相似文献   
58.
 In the present study, the determination of arsenic, lead, cadmium, chromium, cobalt, copper, nickel, mercury and zinc in various cloth samples produced in Kayseri-Turkey was performed after extraction with artificial sweat solution and decomposition with nitric acid. TXRF is shown to be suitable for the determination of 7 trace elements, down to the 0.001 (cobalt) to 0.004 (copper) mg/kg level in textile extract except for mercury and cadmium. The extractable part of the toxic metals by artificial sweat solution is relatively low. In a few extracts the concentration values of Pb and Ni have exceeded their critical values of 0.2 mg/kg for lead and 1.0 mg/kg for nickel given by ?ko-Tex and determined for babys cloths. In addition, it was observed that the element pattern of textile samples resembled ‘finger print type’, TXRF-spectra. This technique can also be used for the identification of textile sample in forensic investigation. Received April 16, 2001 Revision October 1, 2001.  相似文献   
59.
纺织品中残留氯酚的毛细管气相色谱测定法   总被引:2,自引:0,他引:2  
采用稀硫酸浸湿样品,正己烷提取,乙酸酐衍生后以毛细管气相色谱分离测定的方法对纺织品中五氯酚、三氯酚残留量进行了同时测定,探讨了提取、净化及色谱分析条件。方法回收率范围三氯酚84.8%~98.1%,五氯酚88.0%~100.2%。相对标准偏差三氯酚1.54%~2.33%,五氯酚3.48%。方法的检出限(质量分数)分别为2,4,6-三氯酚1.0×10  相似文献   
60.
固相微萃取/气相色谱-质谱检测纺织品中有机磷农药残留   总被引:3,自引:0,他引:3  
采用PDMS萃取纤维一次吸附富集纺织品中马拉硫磷、甲基对硫磷、敌敌畏、三唑磷、对硫磷、喹硫磷、二嗪磷7种有机磷农药,在气相色谱-质谱(GC-MS)进样口热解吸后进行定性定量检测。筛选了几种商品化的萃取纤维,并优化了萃取时间、萃取温度、吸附时间、盐浓度以及pH值等萃取条件。本方法操作简单、快速、环保,检出限低,可适用于生态纺织品中物质的快速检测。  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号