全文获取类型
| 收费全文 | 197篇 |
| 免费 | 23篇 |
| 国内免费 | 8篇 |
专业分类
| 电工技术 | 66篇 |
| 综合类 | 12篇 |
| 化学工业 | 54篇 |
| 金属工艺 | 1篇 |
| 机械仪表 | 3篇 |
| 建筑科学 | 8篇 |
| 矿业工程 | 1篇 |
| 能源动力 | 11篇 |
| 轻工业 | 29篇 |
| 水利工程 | 3篇 |
| 石油天然气 | 1篇 |
| 武器工业 | 1篇 |
| 无线电 | 12篇 |
| 一般工业技术 | 10篇 |
| 冶金工业 | 1篇 |
| 原子能技术 | 4篇 |
| 自动化技术 | 11篇 |
出版年
| 2024年 | 3篇 |
| 2023年 | 9篇 |
| 2022年 | 7篇 |
| 2021年 | 11篇 |
| 2020年 | 8篇 |
| 2019年 | 4篇 |
| 2018年 | 6篇 |
| 2017年 | 7篇 |
| 2016年 | 8篇 |
| 2015年 | 11篇 |
| 2014年 | 24篇 |
| 2013年 | 25篇 |
| 2012年 | 13篇 |
| 2011年 | 22篇 |
| 2010年 | 12篇 |
| 2009年 | 14篇 |
| 2008年 | 9篇 |
| 2007年 | 8篇 |
| 2006年 | 4篇 |
| 2005年 | 10篇 |
| 2004年 | 4篇 |
| 2003年 | 1篇 |
| 2001年 | 4篇 |
| 2000年 | 1篇 |
| 1999年 | 2篇 |
| 1997年 | 1篇 |
排序方式： 共有228条查询结果，搜索用时 15 毫秒
61.
根据源色域是否基于图像可以将色域映射分成两类,设备到设备和图像到设备。图像到设备的方法考虑到了图像色域是设备色域的一个有限子集,这样就能够避免图像的色域被过度压缩从而可以更好地保护颜色的色貌。在一个基于图像的色域映射算法中图像色域的几何精确度是很重要的因素。本文针对图像色域的构建,提出了一种精确度较高的基于旋转球算法(Ball-Pivoting Algorithm)的图像色域的三维可视化的方法。首先我们用一个通常的分析转换方法将要输出的图像从RGB空间转换到CIEL*a*b*颜色空间,然后我们将CIEL*a*b*颜色空间离散化,再将图像的像素点量化到离散空间的网格点。最后基于旋转球算法实现图像色域的网格点重构。实验结果表明提出的方法能够在不失精确度的同时保持较快的速度,这对于开发基于图像的实时色域映射算法有重要意义。 相似文献
62.
Liujun Yang Junwei Yuan Guan Wang Qiang Cao Cheng Zhang Miaomiao Li Junxia Shao Yan Xu Hua Li Jianmei Lu 《Advanced functional materials》2023,33(28):2300954
This study proposes the construction of porous nanomaterial (HOFs@Fe3+) which anchors non-noble metal ions Fe3+ onto nanoscale rod-like hydrogen-bonded organic frameworks (HOFs) by electrostatic and coordination interactions. The high specific surface area and the abundance of hydrogen-bond adsorption active sites in pore structure of HOFs@Fe3+ facilitate strong interactions with the double OH in bisphenol A (BPA), resulting in the highest saturation adsorption of BPA that has been reported so far (452 mg g-1). In addition, the ordered conjugate stacking framework structure and hydrogen bond of HOFs@Fe3+ and the variable valence properties of Fe3+ create new pathways for efficient separation of photogenerated carriers. The results show that HOFs@Fe3+ can completely adsorb and photodegrade 50 ppm BPA within 20 min, owing to the abundant hydrogen bond that acts both as adsorption sites to accelerate the mass transfer process and as catalytic sites to ensure adsorption and photodegradation can be matched synergistically. Meanwhile, the efficiency of photocatalytic H2 production by HOFs@Fe3+ reaches 21.55 mmol g-1 h-1 with non-noble metal Fe3+ as co-catalyst. This tri-functional material with high adsorption capacity, high photodegradation efficiency, and high photocatalytic H2 production activity can be successfully used to solve the long-standing conflict between environment and energy. 相似文献
63.
《Food Control》2013,33(2):549-551
Fresh produce, and in particular minimally processed leafy green vegetables, have been recognized as a source of transmission for foodborne pathogens of animal origin. In South-East Asian and other cultures the leaves of the banana plant (Musa sp.) are widely used as food wrappings or as serving plates because of their waxy surfaces and represent a largely uninvestigated leafy green product. This study was undertaken to quantify the attachment of two strains of each of the three bacterial foodborne pathogens Staphylococcus aureus, Salmonella enterica and Escherichia coli to the top side and underside of banana leaf surfaces. All bacteria tested attached to banana leaves at levels in the range of 3.5–4.5 cfu/cm2. Differences in attachment to leaves between strains were apparent. Most notably both Salmonella strains attached to the top side of leaf surfaces in significantly (p < 0.05) lower numbers than two (one E. coli and one S. aureus) of the other four strains. Furthermore, the two S. aureus strains attached to the undersides of leaves in significantly (p < 0.05) lower numbers than to the top side of leaves. Despite the waxy nature of the banana leaf surfaces the bacteria tested were capable of attaching to them in numbers equivalent to the attachment of bacterial pathogens to other leafy green produce. 相似文献
64.
为解决多种电力系统分析软件不能与PSS/E交互使用的问题,本文利用PSS/E软件开发电力系统元件的自定义模型。首先,选取BPA软件中的一种带PID控制器的电子液压型调速器模型作为参考,并据此建立基于PSS/E的调速器自定义模型。然后,利用单机无穷大系统,在BPA和PSS/E中分别作仿真分析,以检验调速器自定义模型的性能。仿真曲线和误差量化分析表明调速器自定义模型能够正常工作且与源模型的性能非常接近,利用PSS/E的模型自定义功能可以实现电力系统其他仿真软件与PSS/E的交互使用。 相似文献
65.
双酚A(BPA)的内分泌干扰作用以及对人体产生的不良影响,使双酚S(BPS)作为替代品在食品包装材料中应用更加广泛。BPS在大规模应用之前,并没有对其安全性进行充分研究。本文以3T3-L1前脂肪细胞为体外模型,探究BPS对3T3-L1前细胞分化的影响及作用途径,评价BPS安全性的同时,也为肥胖等慢性代谢疾病的预防提供参考。研究结果表明:BPS能促进3T3-L1前脂肪细胞生长,当浓度超过400μmol/L时,才能显著抑制细胞的增殖;BPS能显著诱导分化的3T3-L1细胞内脂质的积累,并呈现非剂量依赖关系;与模型组相比,BPA上调PPARγ、C/EBR和aP2基因的表达,而BPS只作用PPARγ基因的过表达,BPS和BPA都能使GLUT4基因的表达显著下降(p0.01)。总之BPS和BPA作用脂肪细胞分化的途径不完全一样,可能是在多种转录因子的共同作用下完成的。 相似文献
66.
We show that checking weak bisimulation equivalence of two context-free processes (also called BPA-processes) is EXPTIME-hard, even under the condition that the processes are normed. Furthermore, checking weak regularity (finiteness up to weak bisimilarity) for context-free processes is EXPTIME-hard as well. Adding a finite control of the minimal non-trivial size of 2 to the BPA process already makes weak bisimilarity undecidable. 相似文献
67.
68.
《Food additives & contaminants. Part A, Chemistry, analysis, control, exposure & risk assessment》2013,30(2):319-329
Bisphenol A (BPA) is a high-production-volume chemical that is widely used in polycarbonate plastics and epoxy food-can coatings. Following several studies that have reported adverse effects of BPA over the past decade, other bisphenol analogues, such as bisphenol F (BPF), bisphenol S (BPS), bisphenol AF (BPAF), and bisphenol B (BPB), have been gradually developed as substitutes for BPA in several applications. Nevertheless, few studies have reported on the occurrence of compounds other than BPA in foodstuffs. In this study, 289 food samples (13 categories: cereals and cereal products, meat and meat products, fish and seafood, eggs, milk and milk products, bean products, fruits, vegetables, cookies/snacks, beverages, cooking oils, condiments, and others), collected from nine cities in China, were analysed for eight bisphenol analogues using high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). BPA and BPF were found widely in foodstuffs at concentrations ranging from below the limit of quantitation (LOQ) to 299 ng g–1 (mean = 4.94 ng g–1) and from below the LOQ to 623 ng g–1 (mean = 2.50 ng g–1), fresh weight, respectively. The highest total concentrations of bisphenols (∑BPs: sum of eight bisphenols) were found in the category of vegetables that included canned products (mean = 27.0 ng g–1), followed by fish and seafood (16.5 ng g–1) and beverages (15.6 ng g–1). ∑BP concentrations (mean = 2–3 ng g–1) in milk and milk products, cooking oils, and eggs were low. Food samples sold in metallic cans contained higher mean ∑BP concentrations (56.9 ng g–1) in comparison with those packaged in glass (0.43 ng g–1), paper (11.9 ng g–1), or plastic (6.40 ng g–1). The daily dietary intakes of bisphenols were estimated, based on the mean concentrations measured and daily consumption rates of foods, to be 646 and 664 ng kg–1 bw day–1 for men and women, respectively. 相似文献
69.
《Food additives & contaminants. Part A, Chemistry, analysis, control, exposure & risk assessment》2013,30(11):2256-2269
ABSTRACTIn this study a sensitive analytical method based on liquid chromatography-electrospray tandem mass spectrometry (LC-MS/MS) was developed for the simultaneous analysis of bisphenol A (BPA), bisphenol AF (BPAF), bisphenol B (BPB), bisphenol E (BPE), bisphenol F (BPF) and bisphenol S in different paper and board products, including virgin fibre samples and recycled samples. Analytes were extracted from the paper matrix using a simple solvent extraction and chromatographic separation was performed on a C18 core-shell (100 mm x 2.1 mm i.d.; 1.7 µm particle size) column. The developed method showed good linearity (R2 > 0.9921) for all analytes. Absolute recoveries ranged from 71 to 115% and precision in terms of reproducibility and repeatability (intra- and inter-day) yielded in relative standard deviations (RSDs) of less than 15.0% and 17.4%, respectively. The limit of detection (LOD) and limit of quantification (LOQ) for the different analytes ranged from 0.29 to 0.40 µg kg?1 paper and from 1.09 to 1.32 µg kg?1 paper, being in the same range for all analytes. Quantitation of the analytes was performed using the internal standard procedure, with concentrations of < LOQ to 9599 µg kg?1 for the different analytes. Furthermore, a calculation of the maximum migration, assuming the ‘worst case’ scenario of 100% migration was performed. 相似文献
70.
Jun Yang Shulin Hu Anqi Liao Yetian Weng Shuli Liang Ying Lin 《Food Science & Nutrition》2022,10(6):1841-1853
Current chemical analysis approaches for contaminants have failed to reveal their biotoxicity. Moreover, conventional bioassays are time consuming and exhibit poor repeatability. In this study, we performed the acute toxicity detection of various contaminants (chromium (Cr), cadmium (Cd), lead (Pb), arsenic (As), mercury (Hg), tin (Sn), nickel (Ni), and bisphenol A (BPA)) with four bioluminescent bacteria (Vibrio qinghaiensis Q67, V. fischeri, Photobacterium phosphoreum T3, and P. phosphoreum 502) using a rapid, flexible, and low-cost bioassay. We found that the temperature affected the bacterial luminescence, and freeze-dried cells exhibited sensitive toxic responses to contaminants. Indeed, the optimized protectants containing 12% (w/v) trehalose, 4% sucrose, and 2% sorbitol displayed better luminescence and toxic sensitivity. Furthermore, freeze-dried powders of these strains were prepared and subjected to acute toxicity detection. The results showed that all contaminants exhibited acute toxicity toward Q67, but the other strains did not show obvious response to nickel and tin. The relative half-maximal effective concentration (EC50) values of BPA, Cr, Cd, Pb, As, Hg, Ni, and Sn to Q67 were 0.674, 1.313, 11.137, 5.921, 4.674, 0.911, 5.941, and 54.077 mg/L, respectively. In addition, the EC50 values of contaminants toward different strains were suggested to be statistically significant. Freeze-dried Q67 exhibited toxic responses to more contaminants than the other bioluminescent strains; therefore, Q67 was selected to be more suitable than the other strains for single and mixture toxicity detection tests. Compared with other strains, Q67 was more appropriate for the rapid screening of the mixture toxicity of contaminants in samples as a nonspecific screening sensor before the use of standard analysis approaches. 相似文献