全文获取类型
收费全文 | 6090篇 |
免费 | 227篇 |
国内免费 | 6篇 |
专业分类
电工技术 | 139篇 |
综合类 | 9篇 |
化学工业 | 1486篇 |
金属工艺 | 118篇 |
机械仪表 | 128篇 |
建筑科学 | 327篇 |
矿业工程 | 22篇 |
能源动力 | 163篇 |
轻工业 | 717篇 |
水利工程 | 70篇 |
石油天然气 | 17篇 |
无线电 | 417篇 |
一般工业技术 | 857篇 |
冶金工业 | 907篇 |
原子能技术 | 97篇 |
自动化技术 | 849篇 |
出版年
2023年 | 50篇 |
2022年 | 106篇 |
2021年 | 172篇 |
2020年 | 109篇 |
2019年 | 133篇 |
2018年 | 109篇 |
2017年 | 120篇 |
2016年 | 135篇 |
2015年 | 120篇 |
2014年 | 201篇 |
2013年 | 329篇 |
2012年 | 264篇 |
2011年 | 332篇 |
2010年 | 201篇 |
2009年 | 219篇 |
2008年 | 245篇 |
2007年 | 211篇 |
2006年 | 202篇 |
2005年 | 156篇 |
2004年 | 140篇 |
2003年 | 139篇 |
2002年 | 128篇 |
2001年 | 80篇 |
2000年 | 75篇 |
1999年 | 91篇 |
1998年 | 157篇 |
1997年 | 126篇 |
1996年 | 95篇 |
1995年 | 91篇 |
1994年 | 80篇 |
1993年 | 76篇 |
1992年 | 53篇 |
1991年 | 50篇 |
1990年 | 67篇 |
1989年 | 60篇 |
1988年 | 54篇 |
1987年 | 61篇 |
1986年 | 52篇 |
1985年 | 67篇 |
1984年 | 62篇 |
1983年 | 64篇 |
1982年 | 53篇 |
1981年 | 45篇 |
1979年 | 48篇 |
1978年 | 61篇 |
1977年 | 61篇 |
1976年 | 69篇 |
1975年 | 55篇 |
1974年 | 52篇 |
1973年 | 59篇 |
排序方式: 共有6323条查询结果,搜索用时 15 毫秒
101.
Oligobutadiene-based prepolymers and polyurethanes (PU) were prepared from hydroxyl terminated polybutadiene (HTPB), three diisocyanates (aromatic, alicyclic and aliphatic) and two chain extenders (containing hydroxyl or amino groups). The free NCO content in the prepolymers varied systematically and the characteristic of these products were interpreted in terms of NCO group reactivity, propagation reactions and HTPB functionality. The mechanical properties of the polyurethane elastomers derived from the prepolymers were discussed in terms of hard and soft segment structures. 相似文献
102.
Nuclear magnetic resonance spectroscopy has been used to study the dissociation and reaction of N,N′-(2-propyloximino)-4,4′-methylenebis(phenylcarbamate), as a crosslinking agent for polymers containing labile hydrogens. The crosslinking of poly(acrylic acid), polyacrylamide, and poly(vinyl alcohol) was found to result upon heating each to 150°C for 10 min with this component at 2–10 wt %. 相似文献
103.
Walter J. Thomas Mohamed A. El-Sawy Edward W. Palmer 《Chemical Engineering Communications》1982,16(1):53-78
Two published theoretical models are examined and applied to experimental results for absorption and desorption. The system used was CO2/H2O and studies were made for liquid film flow down inclined planes. Experimental results give “Reduced” values of mass ransfer rates.
Interferometric studies give interfacial concentration, penetration and film depths, and take-up of carbon dioxide. In the case of desorption the interferograms are distorted by “deflections.”
All the experimental values for absorption and desorption differ from those calculated from theoretical models.
Desorption is not a mirror image of absorption, and it is approximately 75% of the transfer rate of absorption over a wide operating range.
A comparison is made of the behaviour of static pools and flowing liquid films. 相似文献
Interferometric studies give interfacial concentration, penetration and film depths, and take-up of carbon dioxide. In the case of desorption the interferograms are distorted by “deflections.”
All the experimental values for absorption and desorption differ from those calculated from theoretical models.
Desorption is not a mirror image of absorption, and it is approximately 75% of the transfer rate of absorption over a wide operating range.
A comparison is made of the behaviour of static pools and flowing liquid films. 相似文献
104.
Flor R. Siperstein Carlos Avendaño Jordan J. Ortiz Alejandro Gil-Villegas 《American Institute of Chemical Engineers》2021,67(3):e17186
The isosteric heat of adsorption is an important thermodynamic property used to characterize and optimize adsorption processes. In this work, analytic expressions for isosteric heats of adsorption are derived for a collection of commonly used isotherm models and a two-dimensional molecular equation of state based on the SAFT-VR approach. The use of these expressions is presented with an example of adsorption of nitrous oxide, N2O, on biochar, which is a waste biomass charcoal that exhibits high adsorption potential. The results show that accurate fitting of the adsorption isotherms leads to consistent results obtained with different approaches; however, the predicted isosteric heat of adsorption exhibits strong variations in the regions where experimental data is insufficient such in the region of low pressure/low coverage. Convergence on the prediction of the isosteric heat of adsorption by the different models is only observed in the region where no extrapolation of experimental data is needed. 相似文献
105.
106.
Alejandro Ávila-Ortega José Pablo Avalos-Hernández Rudy Trejo-Tzab Andrés Iván Oliva Juan Antonio Juárez-Moreno 《应用聚合物科学杂志》2021,138(30):50737
Among several oil/water emulsion separation technologies, the utilization of nanoparticle-decorated membranes with diverse functionalities has received considerable attention in recent years, particularly if the antifouling capacity can be improved. In this article, we propose a new membrane based on surface-hydrolyzed polyacrylonitrile electrospun membranes and/or decorated with amine-functionalized Si-MCM-41 nanoparticles to be used as oil/water emulsion separation treatment and to determine their antifouling ability. X-Ray photoelectron spectrometry, attenuated total reflectance Fourier transform infrared spectroscopy, and toluidine blue O assay, scanning electron microscopy, contact angle measurements for oil under water and thermogravimetry were used for characterizing the membranes and an assay of permeability was developed to quantify the diffusion of oil molecules across the electrospun membrane. The electrospun and/or decorated membranes showed an underwater oleophobic wettability, which can separate oil-in-water emulsions with 87% separation efficiency, results of fouling experiments, evaluated in terms of rejection and flux recovery ratio, exhibited good antifouling ability, but the membrane decoration process did not lead to superior outcomes compared with undecorated membranes. 相似文献
107.
We present a model of spatial navigation based on the non-convergent dynamics of brain activity. The system includes a hippocampal module that processes global spatial information and a cortical module that deals with local sensory information. We test the model using several spatial navigation paradigms: goal finding, shortcutting and detouring. Computer simulations show that the performance of the agent qualitatively matches that of animals and related models. This new approach provides a novel interpretation of how the brain accomplishes spatial navigation. 相似文献
108.
109.
110.