全文获取类型
收费全文 | 1350篇 |
免费 | 176篇 |
国内免费 | 89篇 |
专业分类
电工技术 | 39篇 |
综合类 | 70篇 |
化学工业 | 662篇 |
金属工艺 | 55篇 |
机械仪表 | 29篇 |
建筑科学 | 48篇 |
矿业工程 | 52篇 |
能源动力 | 18篇 |
轻工业 | 167篇 |
水利工程 | 2篇 |
石油天然气 | 133篇 |
武器工业 | 2篇 |
无线电 | 41篇 |
一般工业技术 | 246篇 |
冶金工业 | 6篇 |
原子能技术 | 37篇 |
自动化技术 | 8篇 |
出版年
2024年 | 9篇 |
2023年 | 46篇 |
2022年 | 51篇 |
2021年 | 72篇 |
2020年 | 59篇 |
2019年 | 72篇 |
2018年 | 68篇 |
2017年 | 75篇 |
2016年 | 68篇 |
2015年 | 56篇 |
2014年 | 86篇 |
2013年 | 103篇 |
2012年 | 110篇 |
2011年 | 96篇 |
2010年 | 68篇 |
2009年 | 62篇 |
2008年 | 54篇 |
2007年 | 70篇 |
2006年 | 80篇 |
2005年 | 48篇 |
2004年 | 45篇 |
2003年 | 32篇 |
2002年 | 29篇 |
2001年 | 25篇 |
2000年 | 15篇 |
1999年 | 14篇 |
1998年 | 12篇 |
1997年 | 13篇 |
1996年 | 12篇 |
1995年 | 17篇 |
1994年 | 13篇 |
1993年 | 8篇 |
1992年 | 7篇 |
1991年 | 3篇 |
1990年 | 3篇 |
1989年 | 1篇 |
1988年 | 5篇 |
1986年 | 2篇 |
1985年 | 1篇 |
1984年 | 3篇 |
1983年 | 2篇 |
排序方式: 共有1615条查询结果,搜索用时 250 毫秒
71.
The interaction of the main‐chain polycations 2,2‐ionene (I2,2) and 3,3‐ionene (I3,3) with sodium dodecyl sulfate (SDS) has been investigated in aqueous solution. It was confirmed that the interaction is cooperative and a stoichiometric 1:1 complex of I2,2–SDS or I3,3–SDS with regular structure forms as a precipitate irrespective of the molar ratio of the components. It is completely different from the interaction of side‐chain polycations such as the poly[(vinyl pyridine)‐co‐styrene] copolymer cation (PVSC) with SDS, in which no cooperative effect was observed. The driving force responsible for the cooperative effect is believed to be the hydrophobic attraction between the SDS molecule already linked on the ionene chain and the next SDS molecule to be entered. It was also confirmed that the structures of the complexes are very different, ie the ionene–SDS complexes exhibit high regularity whereas the PVSC–SDS complex is irregular. © 2001 Society of Chemical Industry 相似文献
72.
采用脉冲色谱法测定了140℃时疏水多孔硅胶(HPS)上C2~5醇的吸附等温线及醇和水的Henry常数。分析得出,C2~5醇的吸附等温线在醇分压小于2.5kPa时符合Freundlich模型,醇分压小于0.3kPa时符合Langmuir单分子层模型,C2~5直链醇的Henry常数随醇的沸点和碳原子数的增加呈指数性递增,支链醇与HPS表面的作用力更强;醇的Henry常数可以分解为—CH3,—CH2—,—OH基团贡献值的加和,其对数值分别为0.68,0.60,0.46,-11.42;在气相条件下,因HPS的疏水性而使水分子不易接近HPS表面;HPS对醇-醇物系的分离是由于HPS具有基团选择性的特性。 相似文献
73.
电厂实际燃煤的煤质成分与原设计值偏差较大,通过增设DBA脱硫增效系统,使原脱硫设计系统适应实际这种高硫份煤的要求. 相似文献
74.
Jing Jin Sunil Chhatre Nigel J. Titchener‐Hooker Daniel G. Bracewell 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2010,85(2):209-215
BACKGROUND: Production of recombinant virus‐like particles (VLPs) in yeast expression systems for use as vaccines requires cell disruption and detergent‐mediated steps to liberate the product. Typically, these release high levels of cellular components such as lipids that foul chromatography columns. This study compares the impact of applying lipid‐rich and lipid‐depleted feedstocks to hydrophobic interaction chromatography columns to quantify the loss of performance caused by the presence of host lipids over a total of 40 operational cycles. RESULTS: VLP binding capacity in the lipid‐rich feed was significantly lower than for the lipid‐depleted feed, with greater than 24% of the lipids remaining in the column after each cycle. Triacylglycerol was found to be the major contaminant. The effectiveness of subsequent caustic clean‐in‐place was limited, resulting in column hydrophobicity increasing over repeated loading cycles. This improved the effective VLP binding capacity and affinity, but also made product elution more difficult, and recovery decreased by more than 70% over the 40 cycles. CONCLUSION: Host cell lipids cause major fouling problems during VLP purification. Instead of screening for better CIP conditions, priority should be given to identifying suitable upstream lipid removal strategies in order to maintain column performance and so yield more economically viable processes. Copyright © 2009 Society of Chemical Industry 相似文献
75.
In this paper nickel acetate catalyzed sodium borohydride cartridges have been prepared and hydrolyzed with water for hydrogen production. Two technological solutions have been tested to increase the overall hydrogen yield, namely a porous water diffuser and a hydrophobic membrane. The first was used to improve water diffusion inside the hydride while the second to confine water inside the cartridge. The generated hydrogen flow showed a very reproducible behavior. Hydrogen promptly evolved just after water was pumped into the cartridge. After some initial peaks, a constant hydrogen flow has been recorded for the whole reaction time. The constant flow was related to the presence of the porous diffuser. The use of a hydrophobic membrane to confine the water inside the cartridge allowed to increase the overall hydrogen yield: about 6 water molecules per mol of hydride were required to complete the reaction. The reaction product was identified by XRD as Na2B2O4*8H2O. The cartridge hydrogen gravimetric content, based on water and sodium borohydride weight, was as high as 4.64%. 相似文献
76.
BACKGROUND: Hydrophobically modified polyelectrolytes are widely used polymers due to their good water solubility, stretched configuration in water and strong hydrophobic association. The study reported here aimed at researching the double action of hydrophobic association and electrostatic effect of novel hydrophobically modified polyelectrolytes in solution. RESULTS: A series of novel hydrophobically modified polyelectrolytes were synthesized by micellar copolymerization with various feed ratios of sodium 2‐acrylamido‐2‐methylpropanesulfonate, N‐n‐dodecylamine and sodium dodecylsulfonate. Their structure was characterized using Fourier transform infrared spectroscopy, nuclear magnetic resonance and gel permeation chromatography, and the viscosities of their aqueous and salt solutions were studied. CONCLUSION: The results show that the addition of the hydrophobic comonomer results in a decrease in molecular weight (Mw). The smaller the initial number of hydrophobes in one micelle, the higher is Mw of the resulting copolymer. The viscosity of PAD‐1.73 polyelectrolyte is less sensitive to salt than those of the others. According to the zero shear viscosity and corresponding concentration, the critical cluster‐forming concentration, critical overlap concentration and critical entanglement concentration of these polymer solutions were determined. Moreover, in the dilute regime the viscosity decreases with increasing salinity, while in the semi‐dilute regime the viscosity decreases first and then increases. It is suggested that in dilute and semi‐dilute regimes, hydrophobic intramolecular association and intermolecular association dominate, respectively. Copyright © 2009 Society of Chemical Industry 相似文献
77.
考虑完全开放的微管道中液体输运不稳定,不利于生物气溶胶采样和监测的自动化集成,本文提出了用覆盖有疏水网的开放微管道来实现液体的可靠输运.通过理论分析得到了该微管道液体输运特性的估计公式,并用水作为试验介质对其输运特性进行了实验分析.分析实验显示,开放微管道中液体输运的稳定性依赖于栅网特性、液体性质和流动速度、管道尺寸和表面特性.栅网表面疏水性越好,孔径越小,微管道中液体的最大许可压强就越大,液体输运就会越稳定.对于孔径50 μm、表面涂覆有Teflon的栅网,最大许可压强可达2000 Pa.管道中的最大许可流速取决于管道尺寸和最大许可压强;对于较浅、较长的管道,最大许可流速较小.当液体流过干的疏水管道时,液体的表面张力会阻碍流动,管道截面尺寸越小,表面张力的阻碍效果越明显. 相似文献
78.
Sterling Chaffins Garry Hinch Kevin DeKam Vince Waterhous Jim Smith Milo Overbay Dan Bilich Chris Hovermale John Jones 《应用聚合物科学杂志》2012,124(6):4636-4644
The synthesis, formulation, and wafer level processing conditions of a heavily fluorinated hydrophobic photoresist was demonstrated. The synthesis is based on terminal epoxy modification of commercially available perfluoropolyethers. Structural characterization shows that terminal epoxide can open during the synthetic process, but in a simple formulation has a negligible effect on photoresolution of the photoresist. Formulation into a traditional photoresist requires careful selection of appropriate cosolvents to ensure solubility of the hydrophobic epoxy and hydrophilic photoacid generator while attaining adequate coating quality. Formulation processing conditions are presented and the chemical resistance of the resist through aggressive processing steps is demonstrated. Wafer level patterning using traditional photolithographic tools illustrates the applicability of the formulation and process conditions for traditional resist or microfluidic applications. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011 相似文献
79.
《分离科学与技术》2012,47(14):3101-3116
Abstract In this study, the performance of GAC adsorption and biofiltration systems in treating biological treated sewage effluent (BTSE) was evaluated in terms of organic removal efficiency, organic fractions, and molecular weight distribution (MW) of organic matter (OM) removed. The GAC biofilter removed 23.5% and 61% of the hydrophobic fractions and hydrophilic fractions of OM in the BTSE respectively. MW distribution studies of GAC filter and GAC adsorption revealed the following: Hydrophobic fraction of the effluent showed a peak at 345 dalton after GAC biofiltration and 256 dalton after GAC adsorption, whereas, with hydrophilic fractions, peaks at 46,178 and 345 daltons were observed after GAC biofiltration and peaks at 46,178 and 256 daltons after GAC adsorption. Transphilic fraction showed the peaks at 12,783 dalton with GAC biofiltration, and 1,463 dalton with GAC adsorption. The performance of the GAC biofilter was successfully mathematically modelled. 相似文献
80.
建筑外墙和屋面用疏水性非微珠型建筑反射隔热涂料采用纳米隔热粉和纳米辐射粉作为主要功能性填料,可用普通建筑涂料生产工艺生产,产品具有良好的隔热、疏水性,且能减少雨水的渗透,提高建筑节能的效果. 相似文献