全文获取类型
收费全文 | 53076篇 |
免费 | 15572篇 |
国内免费 | 10篇 |
专业分类
电工技术 | 2081篇 |
综合类 | 403篇 |
化学工业 | 23836篇 |
金属工艺 | 559篇 |
机械仪表 | 1079篇 |
建筑科学 | 2263篇 |
矿业工程 | 167篇 |
能源动力 | 923篇 |
轻工业 | 8703篇 |
水利工程 | 395篇 |
石油天然气 | 115篇 |
无线电 | 7203篇 |
一般工业技术 | 13786篇 |
冶金工业 | 819篇 |
原子能技术 | 50篇 |
自动化技术 | 6276篇 |
出版年
2023年 | 623篇 |
2022年 | 315篇 |
2021年 | 860篇 |
2020年 | 2083篇 |
2019年 | 3704篇 |
2018年 | 3507篇 |
2017年 | 3726篇 |
2016年 | 4288篇 |
2015年 | 4517篇 |
2014年 | 4461篇 |
2013年 | 6069篇 |
2012年 | 3074篇 |
2011年 | 2578篇 |
2010年 | 3113篇 |
2009年 | 3120篇 |
2008年 | 2307篇 |
2007年 | 2074篇 |
2006年 | 1884篇 |
2005年 | 1616篇 |
2004年 | 1543篇 |
2003年 | 1505篇 |
2002年 | 1365篇 |
2001年 | 1198篇 |
2000年 | 1128篇 |
1999年 | 552篇 |
1998年 | 255篇 |
1997年 | 196篇 |
1996年 | 227篇 |
1995年 | 208篇 |
1994年 | 178篇 |
1993年 | 241篇 |
1992年 | 163篇 |
1990年 | 166篇 |
1989年 | 184篇 |
1987年 | 172篇 |
1986年 | 191篇 |
1985年 | 172篇 |
1984年 | 176篇 |
1983年 | 180篇 |
1982年 | 159篇 |
1981年 | 205篇 |
1980年 | 170篇 |
1979年 | 169篇 |
1977年 | 155篇 |
1976年 | 159篇 |
1975年 | 203篇 |
1974年 | 191篇 |
1973年 | 367篇 |
1972年 | 215篇 |
1968年 | 154篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
992.
993.
994.
Effect of Initial Annealing Temperature on Microstructural Development and Microhardness in High‐Purity Copper Processed by High‐Pressure Torsion
下载免费PDF全文
![点击此处可从《Advanced Engineering Materials》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Saleh N. Alhajeri Abdulla I. Almazrouee Khaled J. Al‐Fadhalah Terence G. Langdon 《Advanced Engineering Materials》2018,20(1)
The effect of the initial annealing temperature on the evolution of microstructure and microhardness in high purity OFHC Cu is investigated after processing by HPT. Disks of Cu are annealed for 1 h at two different annealing temperatures, 400 and 800 °C, and then processed by HPT at room temperature under a pressure of 6.0 GPa for 1/4, 1/2, 1, 5, and 10 turns. Samples are stored for 6 months after HPT processing to examine the self‐annealing effects. Electron backscattered diffraction (EBSD) measurements are recorded for each disk at three positions: center, mid‐radius, and near edge. Microhardness measurements are also recorded along the diameters of each disk. Both alloys show rapid hardening and then strain softening in the very early stages of straining due to self‐annealing with a clear delay in the onset of softening in the alloy initially annealed at 800 °C. This delay is due to the relatively larger initial grain size compared to the alloy initially annealed at 400 °C. The final microstructures consist of homogeneous fine grains having average sizes of ≈0.28 and ≈0.34 µm for the alloys initially annealed at 400 and 800 °C, respectively. A new model is proposed to describe the behavior of the hardness evolution by HPT in high purity OFHC Cu. 相似文献
995.
Mechanical Properties and Interlaminar Fracture Toughness of Glass‐Fiber‐Reinforced Epoxy Composites Embedded with Shape Memory Alloy Wires
下载免费PDF全文
![点击此处可从《Advanced Engineering Materials》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Li‐Dan Xu Ming‐Fang Shi Xiao‐Yu Sun Zhen‐Qing Wang Bin Yang 《Advanced Engineering Materials》2018,20(3)
996.
High Efficiency Poly(acrylonitrile) Electrospun Nanofiber Membranes for Airborne Nanomaterials Filtration
下载免费PDF全文
![点击此处可从《Advanced Engineering Materials》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Riyadh Al‐Attabi Ludovic F. Dumée Lingxue Kong Jürg A. Schütz Yosry Morsi 《Advanced Engineering Materials》2018,20(1)
997.
Nan Sun Quan‐Ping Zhang Hao‐Ran Sun Wen‐Bin Yang Yuan‐Lin Zhou Jiang‐Feng Song De‐Li Luo 《Advanced Engineering Materials》2018,20(2)
998.
999.
Michelle Elias Erika Nnang‐Obada Bernard Charpentier Antoine Durrbach Severine Beaudreuil 《Hemodialysis international. International Symposium on Home Hemodialysis》2018,22(1):45-49
Introduction: Adequate hemodialysis directly improves health. Puncturing an arteriovenous fistula (AVF) and the amount of blood recirculation greatly affect the quality of dialysis. Few studies have assessed the method to cannulate a fistula and its influence on efficiency of hemodialysis. Methods: This prospective pilot study included 14 patients with end‐stage renal failure receiving regular intermittent hemodialysis. Patients received three consecutive treatments with both needles directed upstream then three consecutive treatments with the venous needle directed upstream and the arterial needle directed downstream. With both techniques, the distance between the needles was kept constant at 2.5 cm. Recirculation rate and Kt/V ratio were measured during each treatment using thermodilution and a diascan Fresenius generator. Findings: The 14 patients received 84 hemodialysis sessions: i.e., 8 (57.1%) males and 6 (42.8%) females, mean age 62.3 ± 15.57 years. Results showed that mean recirculation rates and Kt/V did not significantly differ between the two techniques. Discussion: Because no significant difference was found between the two techniques, the direction of insertion of needles should be decided upon on a case‐by‐case basis depending on the anatomy of the AVF and the feasibility of the puncture. 相似文献
1000.
An overview of the numerous latest research in microfiber humidity sensors is carried out with a specific focus on measurement methods, humidity sensitive materials, probe structures, and sensing properties of different sensors. First, five mainstream measurement structures, including taper, fiber grating, coupler, resonator, and interferometer are reviewed. It is concluded that these measurement structures sense the physicochemical property variations of microfibers or sensitive films and exhibit the change of optical signal when exposed to environment. Second, the basic preparation methods, humidity‐sensing properties, and their advantages and disadvantages as humidity sensitive material are addressed. Then, the advantages and disadvantages of all the above sensing structures are also discussed and compared. Finally, the main existing problems and potential solutions of microfiber humidity sensors are pointed out. 相似文献