全文获取类型
收费全文 | 147306篇 |
免费 | 10891篇 |
国内免费 | 5143篇 |
专业分类
电工技术 | 7379篇 |
技术理论 | 15篇 |
综合类 | 8145篇 |
化学工业 | 25220篇 |
金属工艺 | 7334篇 |
机械仪表 | 8379篇 |
建筑科学 | 10282篇 |
矿业工程 | 3836篇 |
能源动力 | 4354篇 |
轻工业 | 8894篇 |
水利工程 | 2172篇 |
石油天然气 | 7165篇 |
武器工业 | 843篇 |
无线电 | 19589篇 |
一般工业技术 | 19448篇 |
冶金工业 | 8640篇 |
原子能技术 | 1638篇 |
自动化技术 | 20007篇 |
出版年
2024年 | 466篇 |
2023年 | 2150篇 |
2022年 | 3702篇 |
2021年 | 5081篇 |
2020年 | 3884篇 |
2019年 | 3391篇 |
2018年 | 3888篇 |
2017年 | 4318篇 |
2016年 | 3805篇 |
2015年 | 4938篇 |
2014年 | 6367篇 |
2013年 | 8500篇 |
2012年 | 8654篇 |
2011年 | 9557篇 |
2010年 | 8152篇 |
2009年 | 8080篇 |
2008年 | 8127篇 |
2007年 | 7551篇 |
2006年 | 7681篇 |
2005年 | 6687篇 |
2004年 | 4832篇 |
2003年 | 4416篇 |
2002年 | 4275篇 |
2001年 | 3950篇 |
2000年 | 3717篇 |
1999年 | 4110篇 |
1998年 | 3943篇 |
1997年 | 3279篇 |
1996年 | 2904篇 |
1995年 | 2402篇 |
1994年 | 1964篇 |
1993年 | 1571篇 |
1992年 | 1229篇 |
1991年 | 971篇 |
1990年 | 844篇 |
1989年 | 715篇 |
1988年 | 562篇 |
1987年 | 451篇 |
1986年 | 328篇 |
1985年 | 310篇 |
1984年 | 219篇 |
1983年 | 155篇 |
1982年 | 160篇 |
1981年 | 122篇 |
1980年 | 130篇 |
1979年 | 85篇 |
1978年 | 90篇 |
1977年 | 90篇 |
1976年 | 123篇 |
1975年 | 60篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
131.
132.
133.
134.
User Modeling and User-Adapted Interaction - Personality plays a pivotal role at work. Many scholars have investigated the association between personality and language usage habits in the English... 相似文献
135.
Microsystem Technologies - Recently, nonlinear system identification has received increasingly more attention due to its promising applications in engineering fields. It has become a challenging... 相似文献
136.
Sustainable biocomposites have gained considerable interest as an alternative to conventional composites in recent years due to their cost-effectiveness and environmental friendliness. The aim of this study was to investigate the performance and durability behavior of biocomposites from sustainable biocarbon (BC) as compared to conventional established fillers. The poly(butylene terephthalate) (PBT) and its composites reinforced with BC, talc, and glass fiber (GF) were prepared and the durability performances was investigated. The study showed that BC/PBT biocomposites provided a lighter weight alternative to traditionally used fillers. After undergoes thermo-oxidative aging, the mechanical properties of BC/PBT biocomposite were deteriorated. The GF/PBT showed the most stable in retaining its mechanical properties in comparison to the talc/PBT and BC/PBT. The aging behavior and mechanism of the PBT composites were discussed. This study provides further insight on the durability-related properties progression of biocomposites as compared to traditional used fillers. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47722. 相似文献
137.
The Caputo and Caputo–Fabrizio derivative are applied to study a second‐grade nanofluid over a vertical plate. A comparative analysis is presented to study the unsteady free convection of a second‐grade nanofluid with a new time–space fractional heat conduction. The governing equations with mixed time–space fractional derivatives are non‐dimensionalized and solved numerically, and a comparison between the Caputo and the Caputo–Fabrizio models is made. It is found that the temperature is higher for the Caputo–Fabrizio fractional model than the Caputo model, but the higher velocity only exists near the vertical plate for the Caputo–Fabrizio model than the Caputo model. Moreover, the velocity for the Caputo model will exceed the Caputo–Fabrizio model as y evolves. 相似文献
138.
AbstractThe reabsorption characteristics of the lignite treated by low and high temperature drying process were addressed in the paper. The information about the moisture form, functional groups, effective water-filled porosities and equilibrium moisture content of the lignite before and after the drying process was investigated using Differential scanning calorimetry (DSC), Fourier transform infrared (FTIR) spectroscopy, nuclear magnetic resonance (NMR) spectroscopy and a self-made reabsorption device, respectively. The results show that the low drying temperature (140, 190, 230?°C, 10?min, N2) has little impact on the effective water-filled porosities of the resulted samples, whereas it has a great influence on the main oxygen-containing functional groups, which amount firstly decreases and then increases with the drying temperature increasing. In the case of the lignite samples dried under high-temperature (600, 700, 800?°C, 30?s, N2), the amount of the effective water-filled porosity of the sample decreases and the amount of oxygen-containing functional groups increases as the temperature increasing. The reabsorption capability of the high temperature dried sample is much lower than that of the sample treated under low drying temperature. The reabsorption characteristics of the low-temperature dried samples are affected by the amount of the oxygen-containing functional groups, while the effective water-filled porosity is main factor for the lignite samples derived from high temperature drying process. Moreover, the work gives a good evidence that the high-temperature drying process is an effective choose for lignite upgrading. 相似文献
139.
Li Zhang Huiqun Yuan Sheng-Hung Chang Anthony Lam 《The International Journal of Advanced Manufacturing Technology》2020,107(3):1081-1089
With the continuous development of the Internet of Things technology and the proposal of “Made in China 2025”, the construction of IoT applicat 相似文献
140.