全文获取类型
收费全文 | 2915篇 |
免费 | 149篇 |
国内免费 | 28篇 |
专业分类
电工技术 | 57篇 |
综合类 | 10篇 |
化学工业 | 684篇 |
金属工艺 | 67篇 |
机械仪表 | 95篇 |
建筑科学 | 115篇 |
矿业工程 | 7篇 |
能源动力 | 203篇 |
轻工业 | 266篇 |
水利工程 | 37篇 |
石油天然气 | 28篇 |
无线电 | 318篇 |
一般工业技术 | 535篇 |
冶金工业 | 160篇 |
原子能技术 | 56篇 |
自动化技术 | 454篇 |
出版年
2024年 | 12篇 |
2023年 | 57篇 |
2022年 | 134篇 |
2021年 | 174篇 |
2020年 | 147篇 |
2019年 | 152篇 |
2018年 | 164篇 |
2017年 | 168篇 |
2016年 | 178篇 |
2015年 | 82篇 |
2014年 | 150篇 |
2013年 | 248篇 |
2012年 | 186篇 |
2011年 | 218篇 |
2010年 | 152篇 |
2009年 | 136篇 |
2008年 | 117篇 |
2007年 | 87篇 |
2006年 | 46篇 |
2005年 | 33篇 |
2004年 | 28篇 |
2003年 | 28篇 |
2002年 | 30篇 |
2001年 | 29篇 |
2000年 | 20篇 |
1999年 | 19篇 |
1998年 | 39篇 |
1997年 | 31篇 |
1996年 | 32篇 |
1995年 | 27篇 |
1994年 | 21篇 |
1993年 | 10篇 |
1992年 | 14篇 |
1991年 | 9篇 |
1990年 | 14篇 |
1989年 | 11篇 |
1988年 | 14篇 |
1987年 | 5篇 |
1986年 | 7篇 |
1985年 | 13篇 |
1984年 | 7篇 |
1983年 | 10篇 |
1982年 | 6篇 |
1981年 | 4篇 |
1980年 | 3篇 |
1979年 | 3篇 |
1978年 | 4篇 |
1977年 | 6篇 |
1976年 | 4篇 |
1970年 | 1篇 |
排序方式: 共有3092条查询结果,搜索用时 15 毫秒
1.
2.
Murat Ozdemir & Hasan Sadikoglu 《International Journal of Food Science & Technology》1998,33(5):439-444
The effects of addition of κ-carrageenan to solutions containing 40% (w/w) sugar substitute on the rheological properties of these systems were investigated at 25 °C using a rotational viscometer at rotational speeds of 6, 12, 30, and 60 rev min−1 . The flow behaviour of the solutions was adequately described by the power law model with or without yield stress. The consistency index ( K ) and the flow behaviour index ( n ) were determined from shear stress vs. shear rate data. The flow parameters of the solutions depended on the carrageenan concentration. The apparent viscosities of the systems decreased with increasing shear rate, indicating pseudoplastic behaviour. The final carrageenan concentration was found to be an effective factor controlling the degree of sliminess of the model food systems studied. 相似文献
3.
The interaction of different metal oxides such as Co3O4, NiO, Al2O3, Cr2O3, Fe2O3 and SiO2 with Na2SO4 at a temperature of 1100 and 1200 K in flowing oxygen has been studied. The thermogravimetric studies for each system were
carried out as a function of Na2SO4 in the mixture. The presence of different constituents in the reaction products were identified by X-ray diffraction analysis
and the morphologies of the reaction products were characterized using metallography and scanning electron microscopy (SEM).
The formation of products was also investigated by thermodynamic computation of free energies of the reactions and the study
of relevant equilibrium phase diagrams. The soluble species in the aqueous solutions of the reaction products were determined
quantitatively using atomic absorption spectrophotometry.
The high temperature interaction products usually contain a 3-phase structure namely, Na2O·M2O
x
, M2O
x
and metal sulphide and/or metal sulphate. The formation of Na2O·M2O
x
depends upon the solid state solubility of metal oxide in the molten salt at high temperatures. Under limited solubility
conditions Na2O·M2O
x
is invariably formed, but as soon as this condition is relaxed the oxide. M2O
x
, precipitates and forms a separate phase. 相似文献
4.
Habibeh Haddad Dabaghi Abdolmajid Bayandori Moghaddam Mahmood Kazemzad Rassoul Dinarvand Fezze Aryanasab Mohammad Reza Nabid 《Journal of Applied Electrochemistry》2008,38(3):409-413
Electrochemical treatment processes can significantly contribute to the protection of the environment through the minimization
of waste and toxic materials in effluents. From a pharmaceutical point of view and due to the existing resemblance between
the electrochemical and biological reactions, it can be assumed that the oxidation mechanisms on the electrode and in the
body share similar principles. In this paper, the application of electrochemical studies in the design of an environmentally
friendly method was delineated for the new hydrocaffeic acid (HCA, 3,4-dihydroxy hydrocinnamic acid) derivatives synthesis
at carbon electrodes in an undivided cell. In this cell, the EC mechanism reaction was involved, comprising two steps alternatively;
(1) electrochemical oxidation and (2) chemical reaction. In particular, the electro-organic reactions of HCA, an important
biological molecule, were studied in a water–acetonitrile (90:10 v/v) mixture in the presence of benzenesulfinic acid (3) and p-toluenesulfinic acid (4). The research included the use of a variety of experimental techniques, such as cyclic voltammetry, controlled-potential
electrolysis and product spectroscopic identification. 相似文献
5.
Khalid Mahmood Zia Mehdi Barikani Ijaz Ahmad Bhatti Mohammad Zuber Haq Nawaz Bhatti 《应用聚合物科学杂志》2008,109(3):1840-1849
A series of polyurethane (PU) elastomers was prepared by the reaction of poly(?‐caprolactone) and 4,4′‐diphenylmethane diisocyanate, which was extended with a series of chain extenders (CEs) having 2–10 methylene units in their structure. The completion of the reaction was confirmed by Fourier transform infrared spectroscopy. The chemical structures of the synthesized PU samples were characterized with Fourier transform infrared, 1H‐NMR, and 13C‐NMR spectroscopy, and the thermal properties were determined by thermogravimetric analysis, DSC, and dynamic mechanical thermal analysis techniques. The mechanical properties were also studied and are discussed. The thermogravimetric analysis and DSC analysis showed that CE length had a considerable effect on the thermal properties of the prepared samples. The dynamic mechanical thermal analysis and damping peaks were also affected by the number of methylene units in the CE length. The elastomer extended with 1,2‐ethane diol exhibited optimum thermal properties, whereas the elastomer based on 1,10‐decane diol displayed the worst thermal properties. Tensile strength and elongation at break decreased with increasing CE length, whereas hardness showed the opposite trend. The glass‐transition temperature moved toward lower temperatures with increasing CE length. The decrease in the glass‐transition temperature and tensile properties were interpreted in terms of decreasing hard segments and increasing chain flexibility. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 相似文献
6.
We analyze nonlinear coupling of polarized solitons in the presence of initial frequency chirp on the basis of a theoretical model described by a coupled nonlinear Schrödinger equations. We also obtain a threshold condition for the bound state of two polarizations and show analytically that the threshold amplitude for soliton trapping can be controlled by varying the chirp parameter. 相似文献
7.
8.
Steady laminar binary mixed convection flow along a vertical circular cone under the combined buoyancy effects of thermal and species diffusion is studied analytically. The analysis is confined to mass diffusion processes with low concentration levels. In the analysis the surface of the cone is assumed to be at a uniform temperature and uniform concentration. Numerical results for the local Sherwood number, local Nusselt number and local friction factor are presented. Representative temperature, concentration and velocity profiles are also shown. The analysis covers the diffusion of common gases and vapours into air. Considerations are given to the situations where the buoyancy forces assist and oppose the forced convection flow for various possible combinations of the thermal and species diffusion processes. 相似文献
9.
Hasan Abbasi Nozari Hamed Dehghan Banadaki Mohammad Mokhtare Somayeh Hekmati Vahed 《浙江大学学报:C卷英文版》2012,(9):701
This study deals with the neuro-fuzzy (NF) modelling of a real industrial winding process in which the acquired NF model can be exploited to improve control performance and achieve a robust fault-tolerant system. A new simulator model is proposed for a winding process using non-linear identification based on a recurrent local linear neuro-fuzzy (RLLNF) network trained by local linear model tree (LOLIMOT), which is an incremental tree-based learning algorithm. The proposed NF models are compared with other known intelligent identifiers, namely multilayer perceptron (MLP) and radial basis function (RBF). Comparison of our proposed non-linear models and associated models obtained through the least square error (LSE) technique (the optimal modelling method for linear systems) confirms that the winding process is a non-linear system. Experimental results show the effectiveness of our proposed NF modelling approach. 相似文献
10.
Din Salah Ud Shao Junming Kumar Jay Mawuli Cobbinah Bernard Mahmud S. M. Hasan Zhang Wei Yang Qinli 《Knowledge and Information Systems》2021,63(9):2231-2276
Knowledge and Information Systems - Developing effective and efficient data stream classifiers is challenging for the machine learning community because of the dynamic nature of data streams. As a... 相似文献