全文获取类型
收费全文 | 647篇 |
免费 | 21篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 3篇 |
综合类 | 1篇 |
化学工业 | 181篇 |
金属工艺 | 34篇 |
机械仪表 | 9篇 |
建筑科学 | 24篇 |
能源动力 | 12篇 |
轻工业 | 23篇 |
水利工程 | 3篇 |
无线电 | 51篇 |
一般工业技术 | 112篇 |
冶金工业 | 110篇 |
原子能技术 | 4篇 |
自动化技术 | 103篇 |
出版年
2023年 | 24篇 |
2022年 | 31篇 |
2021年 | 25篇 |
2020年 | 11篇 |
2019年 | 15篇 |
2018年 | 23篇 |
2017年 | 13篇 |
2016年 | 13篇 |
2015年 | 14篇 |
2014年 | 21篇 |
2013年 | 27篇 |
2012年 | 26篇 |
2011年 | 26篇 |
2010年 | 20篇 |
2009年 | 15篇 |
2008年 | 24篇 |
2007年 | 21篇 |
2006年 | 26篇 |
2005年 | 14篇 |
2004年 | 14篇 |
2003年 | 13篇 |
2002年 | 15篇 |
2001年 | 19篇 |
2000年 | 10篇 |
1999年 | 7篇 |
1998年 | 37篇 |
1997年 | 16篇 |
1996年 | 19篇 |
1995年 | 9篇 |
1994年 | 9篇 |
1993年 | 5篇 |
1992年 | 4篇 |
1991年 | 6篇 |
1990年 | 4篇 |
1989年 | 8篇 |
1988年 | 4篇 |
1987年 | 5篇 |
1985年 | 5篇 |
1984年 | 4篇 |
1983年 | 7篇 |
1982年 | 11篇 |
1981年 | 8篇 |
1980年 | 13篇 |
1979年 | 5篇 |
1978年 | 5篇 |
1977年 | 7篇 |
1976年 | 2篇 |
1973年 | 4篇 |
1972年 | 2篇 |
1966年 | 1篇 |
排序方式: 共有670条查询结果,搜索用时 921 毫秒
31.
32.
Christian Schroeder Thomas M. Grupp Bernhard Fritz Christoph Schilling Yan Chevalier Sandra Utzschneider Volkmar Jansson 《Journal of materials science. Materials in medicine》2013,24(5):1319-1325
The reduced intraoperative visibility of minimally invasive implanted unicondylar knee arthroplasty makes it difficult to remove bone and cement debris, which have been reported on the surface of damaged and retrieved bearings. Therefore, the aim of this study was to analyze the influence of bone and cement particles on the wear rate of unicompartmental knee prostheses in vitro. Fixed bearing unicompartmental knee prostheses were tested using a knee-wear-simulator according to the ISO standard 14243-1:2002(E) for 5.0 million cycles. Afterwards bone debris (particle size 671 ± 262 μm) were added to the test fluid in a concentration of 5 g/l for 1.5 million cycles, followed by 1.5 million cycles blended with cement debris (particle size 644 ± 186 μm) in the same concentration. Wear rate, knee-kinematics and wear-pattern were analyzed. The wear rate reached 12.5 ± 1.0 mm3/million cycles in the running-in and decreased during the steady state phase to 4.4 ± 0.91 mm3/million cycles. Bone particles resulted in a wear rate of 3.0 ± 1.27 mm3/million cycles with no influence on the wear rate compared to the steady state phase. Cement particles, however, lead to a significantly higher wear rate (25.0 ± 16.93 mm3/million cycles) compared to the steady state phase. The careful removal of extruded cement debris during implantation may help in reducing wear rate. Bone debris are suggested to have less critical influence on the prostheses wear rate. 相似文献
33.
Soran Shwan Louise Olsson Magnus Skoglundh Jonas Jansson 《American Institute of Chemical Engineers》2015,61(1):215-223
The focus of this work is to investigate whether a previously developed microkinetic deactivation model for hydrothermally treated Fe‐BEA as NH3‐SCR catalyst can be applied to describe chemical deactivation of Fe‐BEA due to phosphorous exposure. The model describes the experiments well for Fe‐BEA before and after phosphorous exposure by decreasing the site density, representing deactivation of sites due to formation of metaphosphates blocking the active iron sites, while the kinetic parameters are kept constant. Furthermore, the results show that the activity for low‐temperature selective catalytic reduction (SCR) is very sensitive to loss of active monomeric iron species due to phosphorous poisoning compared to high‐temperature SCR. Finally, the ammonia inhibition simulations show that exposure to phosphorous may affect the internal transport of ammonia between ammonia storage sites buffering the active iron sites, which results in a lower SCR performance during transient conditions. © 2014 American Institute of Chemical Engineers AIChE J, 61: 215–223, 2015 相似文献
34.
Méndez Susana Arenas María Ángeles Niklas Andrea González Rodolfo Conde Ana Sertucha Jon de Damborenea Juan José 《Oxidation of Metals》2019,91(1-2):225-242
Oxidation of Metals - The use of high silicon ductile irons is increasing as they offer some advantages with respect to conventional pearlitic–ferritic grades such as high elongation at... 相似文献
35.
M.-L. Skytt G. Frnert J.-F. Jansson U. W. Gedde 《Polymer Engineering and Science》1996,36(13):1737-1744
A rotational parallel plate rheometer that enables simultaneous measurement of the transient or steady-state rheological properties and infrared dichroism was designed and constructed to study orientation in molten polymers. Measurements can be carried out at shear rates between 0.05 and 300 s−1 and at temperatures between 20 and 300°C. Both shear stress and axial normal force together with dichroism are continuously measured during shear flow. Infrared dichroism data for polypropylene showed excellent agreement with data obtained with a FTIR-instrument. The Hermans orientation function for molten poly(dimethyl siloxane) at steady state showed a strong shear-rate dependence in the region 0.1−20 s−1. Rheological data for molten poly(dimethyl siloxane) agrees with data obtained from a conventional rheometer. 相似文献
36.
Amyloses from selected corn starches were used to measure the glucoses involved in the branching points. The number of glucose α 1,6 glycosidically linked were determined by two different methods: 1) The enzymatic one measures directly quantiatively and specifically the glucoses α, 1,6 linked. 2) The other, a chemical one that measures the different n-methylated glucoses involved in the terminal, α 1,4 linked and α1,6 linked positions. The results obtained through both methodologies clearly indicate a good correlation. Amylose is not linear. It has very small proportion of branches and they are α1,6 glycosidically linked. 相似文献
37.
Gaëtan Compère Jean‐François Remacle Johan Jansson Johan Hoffman 《International journal for numerical methods in engineering》2010,82(7):843-867
In this paper, we identify and propose solutions for several issues encountered when designing a mesh adaptation package, such as mesh‐to‐mesh projections and mesh database design, and we describe an algorithm to integrate a mesh adaptation procedure in a physics solver. The open‐source MAdLib package is presented as an example of such a mesh adaptation library. A new technique combining global node repositioning and mesh optimization in order to perform arbitrarily large deformations is also proposed. We then present several test cases to evaluate the performances of the proposed techniques and to show their applicability to fluid–structure interaction problems with arbitrarily large deformations. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
38.
Niklas Björklund Fredrik S. Pettersson Daniel Tobjörk Ronald Österbacka 《Synthetic Metals》2011,161(9-10):743-747
In this paper we present a method of using blends of two silanes with different functional groups to precisely tune the turn-on-voltage to 0 V. In addition, we show how the transistor behaviour of an amorphous polymer low-voltage transistor is affected by modification of the Al2O3 dielectric with self-assembled monolayers of molecules with different functional groups. Controlling the turn-on voltage is essential for any practical applications, especially for low-voltage transistors. This method opens new doors to designing stable, low-voltage organic circuitry in a reproducible manner. 相似文献
39.
40.
In this work, a sensitivity analysis has been performed on a finite element model of glass-lubricated extrusion of stainless steel tubes. Fifteen model parameters, including ram speed, billet and tool temperatures, friction coefficients and heat transfer coefficients, were considered. The aim of the study was to determine the parameters that are most important for the response of the extrusion force. The relationship between the model parameters and the responses was analyzed by a calculation of two different regression models: one linear polynomial model and one model that includes interaction terms. Additional simulations were then carried out to validate the regression models. The results show that the initial billet temperature is the factor that has the strongest impact on the extrusion force within the parameter ranges studied in this work. The goodness of prediction and goodness of fit are very good for both regression models. 相似文献