全文获取类型
收费全文 | 1553篇 |
免费 | 54篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 33篇 |
化学工业 | 197篇 |
金属工艺 | 18篇 |
机械仪表 | 28篇 |
建筑科学 | 30篇 |
矿业工程 | 5篇 |
能源动力 | 51篇 |
轻工业 | 153篇 |
水利工程 | 4篇 |
无线电 | 135篇 |
一般工业技术 | 170篇 |
冶金工业 | 605篇 |
原子能技术 | 13篇 |
自动化技术 | 166篇 |
出版年
2023年 | 8篇 |
2022年 | 14篇 |
2021年 | 20篇 |
2020年 | 19篇 |
2019年 | 25篇 |
2018年 | 30篇 |
2017年 | 39篇 |
2016年 | 21篇 |
2015年 | 20篇 |
2014年 | 30篇 |
2013年 | 65篇 |
2012年 | 45篇 |
2011年 | 34篇 |
2010年 | 44篇 |
2009年 | 54篇 |
2008年 | 51篇 |
2007年 | 46篇 |
2006年 | 46篇 |
2005年 | 36篇 |
2004年 | 36篇 |
2003年 | 31篇 |
2002年 | 33篇 |
2001年 | 35篇 |
2000年 | 25篇 |
1999年 | 41篇 |
1998年 | 179篇 |
1997年 | 131篇 |
1996年 | 102篇 |
1995年 | 46篇 |
1994年 | 53篇 |
1993年 | 40篇 |
1992年 | 19篇 |
1991年 | 23篇 |
1990年 | 20篇 |
1989年 | 15篇 |
1988年 | 11篇 |
1987年 | 7篇 |
1986年 | 7篇 |
1985年 | 9篇 |
1984年 | 2篇 |
1983年 | 7篇 |
1982年 | 11篇 |
1981年 | 4篇 |
1980年 | 7篇 |
1979年 | 2篇 |
1978年 | 2篇 |
1977年 | 17篇 |
1976年 | 40篇 |
1975年 | 2篇 |
1973年 | 2篇 |
排序方式: 共有1608条查询结果,搜索用时 15 毫秒
61.
R. Polvorosa L.N. Lpez de Lacalle A. J. Snchez Egea A. Fernandez M. Esparta I. Zamakona 《The International Journal of Advanced Manufacturing Technology》2020,106(9):3799-3808
In aerospace industry, tapping is the prime choice for hole threading in jet aero-engine turbine components. Taps are not usually resharpened, unlike other 相似文献
62.
Pineapple Wines Obtained from Saccharification of Its Waste with Three Strains of Saccharomyces cerevisiae
下载免费PDF全文
![点击此处可从《Journal of Food Processing and Preservation》网站下载免费的PDF全文](/ch/ext_images/free.gif)
63.
G. Fernandez J. Moon 《Tunnelling and Underground Space Technology incorporating Trenchless Technology Research》2010,25(5):560-566
Field observations indicate that current engineering practice does not consistently estimate ground water flows into unlined rock excavated tunnels due to various factors that analytical solutions do not take into account. These factors include significant geological features, groundwater drawdown, inadequate estimates of hydraulic conductivity from packer tests, and stress-induced rock-mass permeability reduction in the vicinity of tunnel (lining-like zone). A key variable that is not properly accommodated in current practice, is the hydro-mechanical interaction within the joints in the surrounding rock mass. The significance of this variable is discussed in the 1st part of the paper which presents an analytical solution assessing ground water inflow rate into a tunnel using a mathematical derivation that takes into account the excavation-induced rock permeability reduction in the vicinity of a tunnel based on hydro-mechanical coupling effect. In the 2nd part of the paper, results from numerical analysis are presented to verify the proposed analytical solution for estimating ground water inflow rate into a tunnel. Further studies are currently underway to identify other key variables and their impact on the behavior of unlined tunnels and hydrological flow regime in the surrounding fractured rock mass using a distinct element method program which can fully consider hydro-mechanical coupled behavior of joints. 相似文献
64.
Johnnatan Rodriguez Fernandez Antonio J. Ramirez 《Metallurgical and Materials Transactions A》2017,48(3):1092-1102
Microstructure evolution during friction stir welding (FSW) of mild steel and Ni-based alloy 625 was studied. Regarding the Ni-based alloy, the welding process led to grain refinement caused by discontinuous and continuous dynamic recrystallization, where bulging of the pre-existing grains and subgrain rotation were the primary mechanisms of recrystallization. In the steel, discontinuous dynamic recrystallization was identified as the recovery process experienced by the austenite. Simple shear textures were observed in the regions affected by the deformation of both materials. Although the allotropic transformation obscured the deformation history, the thermo-mechanically affected zone was identified in the steel by simple shear texture components. A new methodology for the study of texture evolution based on rotations of the slip systems using pole figures is presented as an approximation to describe the texture evolution in FSW. 相似文献
65.
J. P. Anais N. Razzouq M. Carvalho C. Fernandez A. Astier 《Drug development and industrial pharmacy》2013,39(2):216-223
We studied different methods of preparing α-tocopherol acetate (ATA) nanoparticles, which are to be used in targeting the lungs as aerosols in order to prevent cigarette smoke toxicity. Poly-(lactide) nanoparticles were prepared using nanoprecipitation and solvent evaporation techniques, which produced, respectively, too small and too large nanoparticles to be aerosolized. The emulsification-diffusion method produced 2 months stable nanoparticles with a size between (500–700 nm). Increasing ATA concentration (1–7 mg/mL) induced a decrease in the association rate (97–93%) and in the adsorbed ATA rate (7–4.5%), which was associated with variations of Zeta potentials (?27.5 to ?24.3 mV) and decrease in polymeric wall thickness and density. 相似文献
66.
L. Ramajo M. Castro J. F. Fernandez F. Rubio-Marcos 《Journal of Materials Science: Materials in Electronics》2017,28(7):5128-5134
The development of (K0.44Na0.52Li0.04)(Nb0.86Ta0.10Sb0.04)O3-based (KNL-NTS) ceramics is attracting great interest because of environmental concerns. Most of the efforts have been concentrated on improving the electrical properties. However, it is desirable to develop ceramics with good electrical response and high mechanical properties. Therefore, the evaluation of the mechanical properties is substantial and little studied. The aim of this work is to study the mechanical properties of KNL-NTS lead free ceramics doped with Zr evaluating the effects that can give rise to improved mechanical properties. Our results show that the crystalline phase, size and shape of grains in the ceramics are affected by the doping amount. We found that the microstructure does have a close relationship to the mechanical response, more specifically; a uniform and fine grain microstructure is suitable to lead high mechanical strength. Based on these results, the chemical modifications with Zr4+ ions have a significantly positive influence on hardness, strength and fracture toughness values of KNL-NTS ceramics. 相似文献
67.
A. Brandolin C. Sarmoria A. Ltpez‐Rodríguez K. S. Whiteley B. Del Amo Fernandez 《Polymer Engineering and Science》2001,41(8):1413-1426
We develop a mathematical model able to describe the complete molecular weight distributions of polyethylene and elhylene‐vinyl acetate copolymers obtained in high pressure autoclave reactors. We apply probability generating function definitions to the mass balances of radical and polymer species in the reacting medium. We use three different definitions of probability generating functions, each one directly applicable either to the number, weight or chromatographic distributions. These probability generating functions are numerically inverted to obtain the corresponding calculated molecular weight distribution. The capabilities of two different inversion methods are compared. Predictions are compared with experimental data obtained in an industrial reactor; good agreement is obtained. The approach presented here is applicable to other types of polymerization reactors and post‐polymerization processes. 相似文献
68.
69.
Equilibrium Moisture Content (EMC) data for medium rough rice grain, Lido variety were obtained by equilibrating rice samples at different Equilibrium Relative Humidities (ERH) and Temperatures. The employed models to fit the data were GAB, modified Chung-Pfost, modified Halsey, Modified Henderson, and modified Oswin. The data were evaluated using the standard error of moisture content, mean relative standard error (%P) of the model and the correlation coefficient r2. The GAB model by indirect regression described the EMC the best, however its parameters lacked of physical meaning. The modified Chung-Pfost and modified Henderson equations presented a similar fit of the EMCERH relationships. The modified Chung-Pfost equation had lower residual values than the modified Henderson equation and was considered the best model to explain the EMC-ERH relationships. 相似文献
70.
Volatile fatty acids production from cheese whey: influence of pH,solid retention time and organic loading rate
下载免费PDF全文
![点击此处可从《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》网站下载免费的PDF全文](/ch/ext_images/free.gif)