全文获取类型
收费全文 | 3023篇 |
免费 | 279篇 |
国内免费 | 154篇 |
专业分类
电工技术 | 113篇 |
综合类 | 190篇 |
化学工业 | 561篇 |
金属工艺 | 186篇 |
机械仪表 | 195篇 |
建筑科学 | 233篇 |
矿业工程 | 87篇 |
能源动力 | 90篇 |
轻工业 | 249篇 |
水利工程 | 54篇 |
石油天然气 | 268篇 |
武器工业 | 31篇 |
无线电 | 249篇 |
一般工业技术 | 368篇 |
冶金工业 | 152篇 |
原子能技术 | 18篇 |
自动化技术 | 412篇 |
出版年
2024年 | 13篇 |
2023年 | 42篇 |
2022年 | 95篇 |
2021年 | 108篇 |
2020年 | 91篇 |
2019年 | 93篇 |
2018年 | 92篇 |
2017年 | 85篇 |
2016年 | 97篇 |
2015年 | 114篇 |
2014年 | 130篇 |
2013年 | 165篇 |
2012年 | 194篇 |
2011年 | 188篇 |
2010年 | 180篇 |
2009年 | 175篇 |
2008年 | 176篇 |
2007年 | 162篇 |
2006年 | 174篇 |
2005年 | 155篇 |
2004年 | 110篇 |
2003年 | 107篇 |
2002年 | 99篇 |
2001年 | 98篇 |
2000年 | 94篇 |
1999年 | 74篇 |
1998年 | 62篇 |
1997年 | 62篇 |
1996年 | 42篇 |
1995年 | 45篇 |
1994年 | 33篇 |
1993年 | 23篇 |
1992年 | 28篇 |
1991年 | 6篇 |
1990年 | 8篇 |
1989年 | 8篇 |
1988年 | 5篇 |
1987年 | 7篇 |
1986年 | 5篇 |
1985年 | 3篇 |
1984年 | 2篇 |
1982年 | 2篇 |
1981年 | 2篇 |
1968年 | 1篇 |
1967年 | 1篇 |
排序方式: 共有3456条查询结果,搜索用时 15 毫秒
91.
This paper presents an experimental investigation into slope failure during water-level drawdown using transparent soil. The internal characteristics of slope failure are not well-known due to the limitations of the techniques used in the experiments conducted to date. In this study, transparent soil is used to visualize the process of slope failure. We developed a water-level control system to implement simulation of the drawdown of the water level at various speeds and used a charge-coupled device camera to capture images during the entire slope failure process. Particle image velocimetry was used to measure the displacement of the sand particles and identify the sliding zones. The flow paths of the fluid inside the slope were illuminated using an organic dye. The results show that the slope failure process can be divided into two stages: surface and overall sliding. The overall sliding of the slope is caused by the gradual development of partial instability, and the failure mode is a cyclic failure. The slope angle is different above and below the water level during the process of sliding. In our experiments, the slope angle is about 20° above the water level, which is the same as the final stable slope angle, and about 35° below the water level, which is the same as the initial slope angle. This means that the drawdown influences the angle above the water level but has little influence on the angle below the water level. The results of this paper provide a better understanding of the physical behavior and failure mode of soil slopes caused by drawdowns near the coast. 相似文献
92.
Yu-Lei Sui Yu-Feng Guo Andrew Yakovlevich Travyanov Tao Jiang Feng Chen Guan-Zhou Qiu 《稀有金属(英文版)》2016,35(12):954-960
Reduction roasting with sodium sulfate followed by magnetic separation was investigated to utilize vanadium tailings with total iron grade of 54.90 wt% and TiO_2 content of 17.40 wt%. The results show that after reduction roasting–magnetic separation with sodium sulfate dosage of 2 wt% at roasting temperature of 1150 °C for roasting time of 120 min, metallic iron concentrate with total iron grade of 90.20 wt%, iron recovery rate of 97.56 % and TiO_2 content of 4.85 wt% is obtained and high-titanium slag with TiO_2 content of 57.31 wt% and TiO_2 recovery rate of 80.27 % is also obtained. The results show that sodium sulfate has a catalytic effect on the reduction of tailings in the novel process by thermodynamics, scanning electron microscopy(SEM) and X-ray diffraction(XRD) and reacts with silica and alumina in the tailings to form sodium silicate and sodium aluminosilicate. Migration of elements and chemical reactions destroy the crystal structures of minerals and promote the reduction of vanadium tailings, resulting in that iron grains grow to large size so that metallic iron concentrate with high total iron grade and low TiO_2 content is obtained. 相似文献
93.
94.
Haifeng Zhang Peng Zhang Qi Sui Kai Zhao Hong Zhou Luquan Ren 《Journal of Materials Engineering and Performance》2017,26(4):1614-1625
In this study, in effort to improve the sliding wear resistance of gray cast iron under wet lubrication conditions, specimens with different bionic units were manufactured and modified according to bionic theory. Inspired by the structure and appearance of biological wear-resistant skin, two kinds of bionic units were processed by laser on the specimen surfaces. We investigated the wear resistance properties of the samples via indentation method and then observed the wear surface morphology of specimens and the stress distributions. The results indicated that coupling the bionic units enhanced the wear resistance of the cast iron considerably compared to the other samples. We also determined the mechanism of wear resistance improvement according to the results. 相似文献
95.
本文从建立复合养老模式的必要性入手,分析养老职能社会化和养老模式多元化的趋势以及目前社区养老存在的不足,提出适应未来常态化养老需求的复合型养老模式的概念,并在此基础上论述其特征、构建原则和三种不同角度的基本构建模式。 相似文献
96.
论述了润滑油系统中清除异物所需的冲洗设备和冲洗材料,并讨论了冲洗方法和冲洗验收标准,以便为确保压缩机安全开车做好供油准备。 相似文献
97.
Crack-free Sm-doped Bi2Ti2O7 (Sm:BTO) thin films with strong (111) orientation have been prepared on Pt (111) substrates using a chemical solution deposition (CSD) method. The structural properties and crystallizations were studied by X-ray diffraction. The surface morphology and quality were examined using atomic force microscopy (AFM). The insulating and dielectric properties were also evaluated at room temperature. The results demonstrate that the Sm:BTO films exhibit improved electrical performances as compared to the pure Bi2Ti2O7 thin films and suggest a strong potential for utilization in microelectronics devices. 相似文献
98.
Influence of fiber surface treatment on mechanical performance of Xanthoceras sorbifolia bunge husk fibers/PP composites
下载免费PDF全文
![点击此处可从《应用聚合物科学杂志》网站下载免费的PDF全文](/ch/ext_images/free.gif)
The PP Composites containing Xanthoceras sorbifolia Bunge husks fibers with different surface treatments were prepared. The mechanical properties such as tensile properties and impact properties of the composites were investigated. It is revealed that the composites with fibers treated by alkali and the following treatments of silane coupling agents KH570, titanate coupling agent JN‐9A, acetic anhydride, MAPP, or bleach, all performed higher in tensile properties than that with untreated fibers, while lower in impact properties. Meanwhile, all treated fibers performed better thermal stability than untreated fibers. The fibers treated by alkali followed by KH570 treatment were added into PP with different contents. It is found that as the fiber content increases, the elastic modulus and impact strength of the composites increase sharply at first followed by a decrease, while the tensile strength decrease initially and increase with a peak at 10%, then decrease continuously. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41217. 相似文献
99.
The flame‐retardant properties and mechanisms of poly(ethylene terephthalate)/hexakis (para‐allyloxyphenoxy) cyclotriphosphazene systems
下载免费PDF全文
![点击此处可从《应用聚合物科学杂志》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Jiawei Li Feng Pan Xiandong Zeng Hong Xu Linping Zhang Yi Zhong Xiaofeng Sui Zhiping Mao 《应用聚合物科学杂志》2015,132(44)
Para‐allyl ether phenol derivative of cyclophosphazene (PACP) was prepared and used as a filler to modify the flame‐retardant properties of poly(ethylene terephthalate) (PET) by melting‐blending. The mechanism of flame‐retardant was discussed and the influences of flame‐retardant contents to the mechanical properties were studied. The results revealed that the incorporation of only 5 phpp PACP (0.37 wt % phosphorus containing) into PET matrix can distinctly increase the flame retardancy of PET/PACP composition, and it has a little effect on the mechanical properties of PET. The high flame‐retardant performance of PET/PACP composite was attributed to the combination of condensed‐phase flame retardant and gas‐phase flame retardant. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42711. 相似文献
100.