全文获取类型
收费全文 | 89076篇 |
免费 | 1443篇 |
国内免费 | 515篇 |
学科分类
工业技术 | 91034篇 |
出版年
2023年 | 104篇 |
2022年 | 144篇 |
2021年 | 237篇 |
2020年 | 197篇 |
2019年 | 189篇 |
2018年 | 14626篇 |
2017年 | 13540篇 |
2016年 | 10154篇 |
2015年 | 823篇 |
2014年 | 463篇 |
2013年 | 652篇 |
2012年 | 3471篇 |
2011年 | 9802篇 |
2010年 | 8600篇 |
2009年 | 5864篇 |
2008年 | 7048篇 |
2007年 | 7997篇 |
2006年 | 348篇 |
2005年 | 1402篇 |
2004年 | 1254篇 |
2003年 | 1315篇 |
2002年 | 739篇 |
2001年 | 242篇 |
2000年 | 286篇 |
1999年 | 120篇 |
1998年 | 146篇 |
1997年 | 94篇 |
1996年 | 100篇 |
1995年 | 72篇 |
1994年 | 68篇 |
1993年 | 49篇 |
1992年 | 32篇 |
1991年 | 37篇 |
1988年 | 24篇 |
1984年 | 24篇 |
1969年 | 24篇 |
1968年 | 45篇 |
1967年 | 34篇 |
1966年 | 42篇 |
1965年 | 46篇 |
1963年 | 31篇 |
1962年 | 22篇 |
1961年 | 19篇 |
1960年 | 30篇 |
1959年 | 35篇 |
1958年 | 37篇 |
1957年 | 37篇 |
1956年 | 34篇 |
1955年 | 65篇 |
1954年 | 68篇 |
排序方式: 共有10000条查询结果,搜索用时 765 毫秒
1.
Aziz Boutouil Ilhame Elazhary Hicham Ben El Ayouchia Hafid Anane Mohammadine El Haddad 《Journal of Adhesion Science and Technology》2020,34(5):549-578
Abstract4-[4-(1H-imidazol-1-yl)methyl)-1H-1,2,3-triazol-1-yl]methylbenzophenone (ITBP) and 4[4-(1H-1,2,4-triazol-1-yl)methyl)-1H-1,2,3-triazol-1-yl]methylbenzophenone (TTBP) are synthesized as new heterocyclic compounds of the triazole derivative family and tested successfully as potential inhibitors for MS in 1?M H2SO4 corrosive medium by using gravimetric analysis, electrochemical impedance spectroscopy, potentiodynamic polarization, and energy dispersive X-ray spectroscopy (EDX). Polarization curves show that the tested inhibitors are mixed-type inhibitors. Scanning electron microscopy (SEM) affirmed the existence of an adsorbed film on the steel surface. Monte Carlo simulations were in excellent agreement with the experimental tests. Abbreviation: PDP: Potentiodynamic Polarization; EIS: Electrochemical impedance spectroscopy; DFT: Density functional theory; MC: Monte Carlo 相似文献
2.
3.
4.
Yingcai Bi Menglu Lan Jiaxin Li Shupeng Lai Ben M. Chen 《Asian journal of control》2019,21(4):1732-1744
Micro Aerial Vehicles (MAVs) have great potentials to be applied for indoor search and rescue missions. In this paper, we propose a modular lightweight design of an autonomous MAV with integrated hardware and software. The MAV is equipped with the 2D laser scanner, camera, mission computer and flight controller, running all the computation onboard in real time. The onboard perception system includes a laser‐based SLAM module and a custom‐designed visual detection module. A dual Kalman filter design provides robust state estimation by multiple sensor fusion. Specifically, the fusion module provides robust altitude measurement in the circumstance of surface changing. In addition, indoor‐outdoor transition is explicitly handled by the fusion module. In order to efficiently navigate through obstacles and adapt to multiple tasks, a task tree‐based mission planning method is seamlessly integrated with path planning and control modules. The MAV is capable of searching and rescuing victims from unknown indoor environments effectively. It was validated by our award‐winning performance at the 2017 International Micro Air Vehicle Competition (IMAV 2017), held in Toulouse, France. The performance video is available on https://youtu.be/8H19ppS_VXM . 相似文献
5.
The Journal of Supercomputing - Data center network virtualization is being considered as a promising technology to provide a performance guarantee for cloud computing applications. One important... 相似文献
6.
Mobile software applications have to cope with a particular environment that involves small size, limited resources, high autonomy requirements, competitive business models and many other challenges. To provide development guidelines that respond to these needs, several practices have been introduced; however, it is not clear how these guidelines may contribute to solve the issues present in the mobile domain. Furthermore, the rapid evolution of the mobile ecosystem challenges many of the premises upon which the proposed practices were designed. In this paper, we present a survey of the literature on software assurance practices for mobile applications, with the objective of describing them and assessing their contribution and success. We identified, organized and reviewed a body of research that spans in three levels: software development processes, software product assurance practices, and software implementation practices. By carrying out this literature survey, we reviewed the different approaches that researchers on Software Engineering have provided to address the needs that raise in the mobile software development arena. Moreover, we review the evolution of these practices, identifying how the constant changes and modernization of the mobile execution environment has impacted the methods proposed in the literature. Finally, we introduced discussion on the application of these practices in a real productive setting, opening an area for further research that may determine if practitioners have followed the proposed assurance paradigms. 相似文献
7.
This paper presents an integrated passive damping approach in hybrid metal-CFRP parts for structural applications. In this concept a viscoelastic material is embedded in the joint zone of the hybrid component. To examine the connection strength single-lap-joint specimens were produced and tested and the influence of the used material combinations, different surface structures, and different process parameters i.e. the moment of cross-linking were evaluated. Afterwards, the metal-CFRP hybrids were tested in quasi-static tests to assess their connection strength and failure behaviour. Dynamic cyclic tensile tests with step-wise increased loading conditions were performed to determine the specimens damping behaviour and to estimate their fatigue performance. Finally, these results are compared to a state of the art metal-CFRP hybrid with rivets connecting both materials. 相似文献
8.
In this paper, we consider the classical finite mixture model, which is an effective tool for modeling lifetime distributions for random samples from heterogeneous populations. We discuss new results on stochastic comparison for two finite mixtures when each of them is drawn from one of the following semiparametric families, i.e., proportional hazards, accelerated lifetime and proportional reversed hazards. 相似文献
9.
10.