全文获取类型
收费全文 | 517330篇 |
免费 | 37658篇 |
国内免费 | 19188篇 |
专业分类
电工技术 | 28387篇 |
技术理论 | 71篇 |
综合类 | 30185篇 |
化学工业 | 87373篇 |
金属工艺 | 27461篇 |
机械仪表 | 32078篇 |
建筑科学 | 41325篇 |
矿业工程 | 15467篇 |
能源动力 | 14789篇 |
轻工业 | 29789篇 |
水利工程 | 8366篇 |
石油天然气 | 32676篇 |
武器工业 | 3797篇 |
无线电 | 59131篇 |
一般工业技术 | 62207篇 |
冶金工业 | 28602篇 |
原子能技术 | 4986篇 |
自动化技术 | 67486篇 |
出版年
2024年 | 1967篇 |
2023年 | 7512篇 |
2022年 | 13372篇 |
2021年 | 18776篇 |
2020年 | 14359篇 |
2019年 | 11852篇 |
2018年 | 13598篇 |
2017年 | 15424篇 |
2016年 | 13948篇 |
2015年 | 18379篇 |
2014年 | 24129篇 |
2013年 | 30091篇 |
2012年 | 30843篇 |
2011年 | 34806篇 |
2010年 | 29693篇 |
2009年 | 28782篇 |
2008年 | 27899篇 |
2007年 | 26979篇 |
2006年 | 28256篇 |
2005年 | 25178篇 |
2004年 | 16486篇 |
2003年 | 14594篇 |
2002年 | 13095篇 |
2001年 | 12003篇 |
2000年 | 12690篇 |
1999年 | 15050篇 |
1998年 | 13251篇 |
1997年 | 10978篇 |
1996年 | 10218篇 |
1995年 | 8573篇 |
1994年 | 7084篇 |
1993年 | 5207篇 |
1992年 | 4135篇 |
1991年 | 3191篇 |
1990年 | 2520篇 |
1989年 | 2108篇 |
1988年 | 1688篇 |
1987年 | 1182篇 |
1986年 | 916篇 |
1985年 | 689篇 |
1984年 | 462篇 |
1983年 | 409篇 |
1982年 | 373篇 |
1981年 | 286篇 |
1980年 | 263篇 |
1979年 | 168篇 |
1978年 | 104篇 |
1977年 | 109篇 |
1976年 | 143篇 |
1975年 | 62篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
Fluorescence‐Activated Cell Sorters: Standing Surface Acoustic Wave (SSAW)‐Based Fluorescence‐Activated Cell Sorter (Small 40/2018) 下载免费PDF全文
3.
World Wide Web - Infectious diseases such as Influenza and Ebola pose a serious threat to everyone but certain demographics and cohorts face a higher risk of infection than others. This research... 相似文献
4.
Wesley P. Chan Hiroto Mizohana Xiangyu Chen Yasuto Shiigi Yoshiyuki Yamanoue Masaki Nagatsuka Masayuki Inaba 《野外机器人技术杂志》2019,36(1):17-33
The use of field robots can greatly decrease the amount of time, effort, and associated risk compared to if human workers were to carryout certain tasks such as disaster response. However, transportability and reliability remain two main issues for most current robot systems. To address the issue of transportability, we have developed a lightweight modularizable platform named AeroArm. To address the issue of reliability, we utilize a multimodal sensing approach, combining the use of multiple sensors and sensor types, and the use of different detection algorithms, as well as active continuous closed‐loop feedback to accurately estimate the state of the robot with respect to the environment. We used Challenge 2 of the 2017 Mohammed Bin Zayed International Robotics Competition as an example outdoor manipulation task, demonstrating the capabilities of our robot system and approach in achieving reliable performance in the fields, and ranked fifth place internationally in the competition. 相似文献
5.
World Wide Web - The wide spread use of positioning and photographing devices gives rise to a deluge of traffic trajectory data (e.g., vehicle passage records and taxi trajectory data), with each... 相似文献
6.
7.
8.
9.
Within the framework of the effective-mass approximation and the dipole approximation, considering the three-dimensional confinement of the electron and hole and the strong built-in electric field(BEF) in strained wurtzite Zn O/Mg0:25Zn0:75O quantum dots(QDs), the optical properties of ionized donor-bound excitons(D+, X)are investigated theoretically using a variational method. The computations are performed in the case of finite band offset. Numerical results indicate that the optical properties of(D+, X) complexes sensitively depend on the donor position, the QD size and the BEF. The binding energy of(D+, X) complexes is larger when the donor is located in the vicinity of the left interface of the QDs, and it decreases with increasing QD size. The oscillator strength reduces with an increase in the dot height and increases with an increase in the dot radius. Furthermore, when the QD size decreases, the absorption peak intensity shows a marked increment, and the absorption coefficient peak has a blueshift. The strong BEF causes a redshift of the absorption coefficient peak and causes the absorption peak intensity to decrease remarkably. The physical reasons for these relationships have been analyzed in depth. 相似文献
10.
Magnetic Resonance Materials in Physics, Biology and Medicine - To investigate the value of using diffusion-weighted imaging (DWI) and intravoxel incoherent motion DWI (IVIM-DWI) to assess the... 相似文献