全文获取类型
收费全文 | 2391篇 |
免费 | 308篇 |
国内免费 | 57篇 |
专业分类
电工技术 | 186篇 |
综合类 | 49篇 |
化学工业 | 1014篇 |
金属工艺 | 54篇 |
机械仪表 | 16篇 |
建筑科学 | 21篇 |
矿业工程 | 13篇 |
能源动力 | 259篇 |
轻工业 | 85篇 |
水利工程 | 5篇 |
石油天然气 | 39篇 |
武器工业 | 2篇 |
无线电 | 401篇 |
一般工业技术 | 523篇 |
冶金工业 | 51篇 |
原子能技术 | 27篇 |
自动化技术 | 11篇 |
出版年
2024年 | 15篇 |
2023年 | 229篇 |
2022年 | 60篇 |
2021年 | 178篇 |
2020年 | 183篇 |
2019年 | 138篇 |
2018年 | 99篇 |
2017年 | 97篇 |
2016年 | 88篇 |
2015年 | 83篇 |
2014年 | 117篇 |
2013年 | 124篇 |
2012年 | 100篇 |
2011年 | 127篇 |
2010年 | 98篇 |
2009年 | 95篇 |
2008年 | 107篇 |
2007年 | 110篇 |
2006年 | 98篇 |
2005年 | 81篇 |
2004年 | 61篇 |
2003年 | 63篇 |
2002年 | 72篇 |
2001年 | 49篇 |
2000年 | 45篇 |
1999年 | 32篇 |
1998年 | 38篇 |
1997年 | 29篇 |
1996年 | 25篇 |
1995年 | 10篇 |
1994年 | 15篇 |
1993年 | 15篇 |
1992年 | 18篇 |
1991年 | 10篇 |
1990年 | 7篇 |
1989年 | 3篇 |
1988年 | 13篇 |
1987年 | 4篇 |
1986年 | 3篇 |
1985年 | 3篇 |
1984年 | 7篇 |
1983年 | 3篇 |
1982年 | 2篇 |
1951年 | 2篇 |
排序方式: 共有2756条查询结果,搜索用时 296 毫秒
111.
A.K. Arof M.F. Aziz M.M. Noor M.A. Careem L.R.A.K. Bandara C.A. Thotawatthage W.N.S. Rupasinghe M.A.K.L. Dissanayake 《International Journal of Hydrogen Energy》2014
This paper reports the effect of using a mixed iodide salt system with two dissimilar cations to enhance the efficiency of dye-sensitized solar cells made with polyvinylidenefluoride (PVdF) based gel electrolyte. Instead of a single iodide salt, a mixture of potassium iodide (KI) with a small K+ cation and tetrapropylammonium iodide (Pr4NI) with a bulky Pr4N+ cation were used to provide the required iodide ion conductivity. Solar cells of configuration FTO/TiO2/Dye/electrolyte/Pt/FTO were fabricated using a mesoporous TiO2 electrode sensitized with a Ruthenium dye (N719). With identical electrolyte compositions, the cells with KI and Pr4NI alone gave efficiencies of 2.37% and 2.90% respectively. The cell with the mixed iodide system, KI:Pr4NI = 16.6:83.4 (% weight ratio), however, showed an enhanced efficiency of 3.92% with a short circuit current density of 9.16 mA cm−2, open circuit voltage of 674.4 mV and a fill factor of 63.4%. 相似文献
112.
The cyclic watergas shift reactor (CWGSR) is a cyclically operated fixed bed reactor for the production of hydrogen. It is based on the alternating reduction of an iron oxide fixed bed with synthesis gas and its subsequent oxidation with steam. We show experimental data of moving reaction zones in a tubular CWGSR. Based on this data and to help further design of these reactors, we propose a dynamic, one-dimensional model of the reactor. The formulated process model was fitted to experimental data by adjusting only two parameters describing the catalytic activity and the oxygen capacity of the fixed bed. Exemplary simulation results are shown. 相似文献
113.
《Journal of Nuclear Science and Technology》2013,50(10):731-736
Chlorinated benzenes dissolved in deoxygenated alkaline 2-propanol were dechlorinated by irradiating with 60Co γ-rays to produce the lower chlorinated benzenes and chloride ion. The yield of dechlorination was found to depend on the number of chlorine atoms on the benzene ring, the G (CI?)-values being, for instance, 6,500, 480 and 2.0 for 0.07 M penta-chlorobenzene, 1, 2, 4-trichlorobenzene, and monochlorobenzene, respectively, in 0.2 M KOH-2-propanol solution. In contrast, the values of G(C1?) differed little between the isomers of trichlorobenzene. The large difference in G (CI?) according to the number of chlorine atoms can be explained by considering the redox potential of the chlorinated benzenes and the ketyl radical ion. Trichlorobenzene is dechlorinated to dichlorobenzene and then to monochlorobenzene while producing potassium chloride and acetone, and consuming hydroxide ion. In the experiment, some chlorinated benzene derivatives were observed to be generated in the course of this process—probably dichlorophenyl-2-propanol and monochlorophenyl-2-propanol, judging from observation by gaschromatograph-mass spectrometer and from the path-way of formation. The observation also indicated the presence of dichlorophenyl-2-propanol in predominant amounts in 1, 3, 5-trichlorobenzene solution, but only in a small fraction in 1, 2, 3-trichlorobenzene. 相似文献
114.
This paper describes the development and performance of a new rapid amperometric biosensor for fructose monitoring in food analysis. The biosensor is based on the activity of fructose dehydrogenase (FDH) immobilised into a carbon nanotube paste electrode according to two different procedures. The direct wiring of the FDH in a highly original osmium-polymer hydrogel was found to offer a better enzyme entrapment compared to the immobilisation of the enzyme in an albumin hydrogel. The optimised biosensor required only 5 U of FDH and kept the 80% of its initial sensitivity after 4 months. During this time, the biosensor showed a detection limit for fructose of 1 μM, a large linear range between 0.1 and 5 mM, a high sensitivity (1.95 μA cm−2 mM), good reproducibility (RSD = 2.1%) and a fast response time (4 s). 相似文献
115.
The polymerization of acrylamide (AAm) was carried out with a potassium permanganate–Titriplex VI redox initiator system with and without electrolysis. Because of the high metal‐ion concentration in general, low‐molecular‐weight polymers were obtained (weight‐average molecular weight = 2600–4000). The effect of potassium permanganate and AAm concentrations and temperature on the polymerization yield was studied and compared with results obtained under the same experimental conditions used for electrolysis. The results of Fourier transform infrared spectroscopy, atomic absorption spectrometry, and scanning electron microscopy (SEM) results are given. SEM micrographs of the polymer obtained by electrochemical methods exhibited smoother surfaces than those obtained by nonelectrolytic methods. In the absence of potassium permanganate, there was no polymerization under experimental conditions. A possible reaction mechanism is suggested. The electro‐induced system resulted in about a 50% increase in the yield. Manganese content in the electro‐induced and chemical polymerization systems were 2.7 and 8.2%, respectively, supporting the yield increase in the electro‐induced system. A graphite electrode was used and resulted in a high yield and a fibrous polymeric structure. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 1526–1534, 2001 相似文献
116.
Liang XU Yan-hang XIONG Jin-wei MENG Jia-bao WANG Zhong-sheng HUA Yong-pan TIAN Jing-lin YOU Zhuo ZHAO 《中国有色金属学会会刊》2021,31(5):1496-1505
An electrochemical study on the redox behavior of indium in the eutectic LiCl-KCl system at 450 °C was carried out with the transient techniques of cyclic voltammetry and chronopotentiometry on an inert molybdenum electrode. The reduction of In(III) was found to be a two-step process involving In(III)/In(I) and In(I)/In couples at the potentials of about ?0.4 and ?0.8 V versus Ag/AgCl, respectively. The redox mechanism was further confirmed by the theoretical evaluation of the number of transferred electrons based on cyclic voltammetry and characterizations of the precipitates generated by the potentiostatic electrolysis. The diffusion coefficients of indium ions in the eutectic LiCl-KCl melt at 450 °C were estimated by cyclic voltammetry and chronopotentiometry. The results obtained through the two methods are in fair agreement, delivering an average diffusion coefficient of approximately 1.8×10?5 cm2/s for In(III), and 1.4×10?4 cm2/s for In(I). 相似文献
117.
118.
119.
120.
Thiol Redox and pKa Properties of Mycothiol,the Predominant Low‐Molecular‐Weight Thiol Cofactor in the Actinomycetes
下载免费PDF全文
![点击此处可从《Chembiochem : a European journal of chemical biology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Dr. Sunil V. Sharma Dr. Koen Van Laer Prof. Joris Messens Dr. Chris J. Hamilton 《Chembiochem : a European journal of chemical biology》2016,17(18):1689-1692
The thiol pKa and standard redox potential of mycothiol, the major low‐molecular‐weight thiol cofactor in the actinomycetes, are reported. The measured standard redox potential reveals substantial discrepancies in one or more of the other previously measured intracellular parameters that are relevant to mycothiol redox biochemistry. 相似文献