全文获取类型
收费全文 | 412073篇 |
免费 | 20379篇 |
国内免费 | 11884篇 |
专业分类
电工技术 | 19061篇 |
技术理论 | 4篇 |
综合类 | 14496篇 |
化学工业 | 58831篇 |
金属工艺 | 21205篇 |
机械仪表 | 18526篇 |
建筑科学 | 20499篇 |
矿业工程 | 6143篇 |
能源动力 | 11362篇 |
轻工业 | 37050篇 |
水利工程 | 6065篇 |
石油天然气 | 9669篇 |
武器工业 | 2011篇 |
无线电 | 51507篇 |
一般工业技术 | 61517篇 |
冶金工业 | 56757篇 |
原子能技术 | 5779篇 |
自动化技术 | 43854篇 |
出版年
2023年 | 3172篇 |
2022年 | 6396篇 |
2021年 | 9188篇 |
2020年 | 6770篇 |
2019年 | 5848篇 |
2018年 | 7225篇 |
2017年 | 8097篇 |
2016年 | 7495篇 |
2015年 | 9521篇 |
2014年 | 12739篇 |
2013年 | 22104篇 |
2012年 | 18680篇 |
2011年 | 21529篇 |
2010年 | 19052篇 |
2009年 | 18974篇 |
2008年 | 19408篇 |
2007年 | 18849篇 |
2006年 | 17175篇 |
2005年 | 14452篇 |
2004年 | 11772篇 |
2003年 | 10935篇 |
2002年 | 10730篇 |
2001年 | 10333篇 |
2000年 | 8939篇 |
1999年 | 8916篇 |
1998年 | 18128篇 |
1997年 | 12884篇 |
1996年 | 10144篇 |
1995年 | 7718篇 |
1994年 | 6751篇 |
1993年 | 6245篇 |
1992年 | 4467篇 |
1991年 | 4298篇 |
1990年 | 3822篇 |
1989年 | 3709篇 |
1988年 | 3580篇 |
1987年 | 3000篇 |
1986年 | 2927篇 |
1985年 | 3451篇 |
1984年 | 3085篇 |
1983年 | 2766篇 |
1982年 | 2574篇 |
1981年 | 2605篇 |
1980年 | 2470篇 |
1979年 | 2293篇 |
1978年 | 2241篇 |
1977年 | 2816篇 |
1976年 | 4178篇 |
1975年 | 1907篇 |
1974年 | 1801篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
101.
The ennoblement of corrosion potential (Ecorr) of passive metal immersed in seawater was investigated with electrochemical technology and epifluorescence microscopy. The in situ observation showed that the bacteria number increased on the metal surface according to an exponential law which was in the same way with the ennoblement of Ecorr. At the same time, the anodic polarization current of high‐Mo stainless steel decreased in the initial days. According to the mix‐potential theory and the characteristics of polarization curves of high‐Mo steel in natural seawater, the ennoblement of corrosion potential may be induced by the decrease of the passive current density. 相似文献
102.
This paper presents a valve-regulated lead acid (VRLA) battery reserve life estimation scheme. The scheme is adaptive in both type and frequency of involvement. The scheme is based on capacity trending with the support of a number of state-of-health (SOH) indicators. These SOH indicators include accumulated thermal stress, float voltage, and indicators acquired from the start-of-discharge (coup de fouet) region. An implementation test case is given, indicating that the scheme is capable of providing an accurate estimation of reserve life long before the end of life. Furthermore, the estimation accuracy improves as the end of battery life approaches. 相似文献
103.
Jānis Bārzdiņš Rūsiņš Freivalds Carl H. Smith 《Journal of Computer and System Sciences》2008,74(4):527-545
We study learning of predicate logics formulas from “elementary facts,” i.e. from the values of the predicates in the given model. Several models of learning are considered, but most of our attention is paid to learning with belief levels. We propose an axiom system which describes what we consider to be a human scientist's natural behavior when trying to explore these elementary facts. It is proved that no such system can be complete. However we believe that our axiom system is “practically” complete. Theorems presented in the paper in some sense confirm our hypothesis. 相似文献
104.
H.J. Bolink E. Coronado D. Repetto M. Sessolo E.M. Barea J. Bisquert G. Garcia‐Belmonte J. Prochazka L. Kavan 《Advanced functional materials》2008,18(1):145-150
A new type of bottom‐emission electroluminescent device is described in which a metal oxide is used as the electron‐injecting contact. The preparation of such a device is simple. It consists of the deposition of a thin layer of a metal oxide on top of an indium tin oxide covered glass substrate, followed by the solution processing of the light‐emitting layer and subsequently the deposition of a high‐workfunction (air‐stable) metal anode. This architecture allows for a low‐cost electroluminescent device because no rigorous encapsulation is required. Electroluminescence with a high brightness reaching 5700 cd m–2 is observed at voltages as low as 8 V, demonstrating the potential of this new approach to organic light‐emitting diode (OLED) devices. Unfortunately the device efficiency is rather low because of the high current density flowing through the device. We show that the device only operates after the insertion of an additional hole‐injection layer in between the light‐emitting polymer (LEP) and the metal anode. A simple model that explains the experimental results and provides avenues for further optimization of these devices is described. It is based on the idea that the barrier for electron injection is lowered by the formation of a space–charge field over the metal‐oxide–LEP interface due to the build up of holes in the LEP layer close to this interface. 相似文献
105.
Wei Li Zhang Wei Pan Bin Luo Xi Hua Zou Meng Yao Wang 《Photonics Technology Letters, IEEE》2008,20(9):712-714
A theoretical construction of one-to-many (OTM) and many-to-one (MTO) chaos synchronization communications using semiconductor lasers is presented. One center laser provides strong injections (strong link) to other side lasers, and the side lasers also provide weak injections (weak link) to the center one. Simulation results show that the side lasers synchronize with the center laser through injection-locking. In addition, messages transmitted via the strong links or the weak links experience strong chaos pass filtering, enabling us to realize OTM and MTO communications. 相似文献
106.
Xin Sun Qiang Lu Moroz V. Takeuchi H. Gebara G. Wetzel J. Shuji Ikeda Changhwan Shin Tsu-Jae King Liu 《Electron Device Letters, IEEE》2008,29(5):491-493
A tri-gate bulk MOSFET design utilizing a low-aspect-ratio channel is proposed to provide an evolutionary pathway for CMOS scaling to the end of the roadmap. 3-D device simulations indicate that this design offers the advantages of a multi-gate FET (reduced variability in performance and improved scalability) together with the advantages of a conventional planar MOSFET (low substrate cost and capability for dynamic threshold-voltage control). 相似文献
107.
108.
魏巍 《重庆科技学院学报(社会科学版)》2008,(12)
缺乏有力的监督和制约机制是我国行政判决执行难的重要原因之一.主张赋予检察机关时行政诉讼执行环节实施法律监督的权利.从而有效防止执行程序违法.抑制怠于执行和拖延执行现象的发生.阐述了由检察机关实施监督的法理依据,介绍了检察监督的方式. 相似文献
109.
110.
Rajoo R. Lim S.S. Wong E.H. Hnin W.Y. Seah S.K.W. Tay A.A.O. Iyer M. Tummala R.R. 《Advanced Packaging, IEEE Transactions on》2008,31(2):377-385
A wafer level packaging technique has been developed with an inherent advantage of good solder joint co-planarity suitable for wafer level testing. A suitable weak metallization scheme has also been established for the detachment process. During the fabrication process, the compliancy of the solder joint is enhanced through stretching to achieve a small shape factor. Thermal cycling reliability of these hourglass-shaped, stretch solder interconnections has been found to be considerably better than that of the conventional spherical-shaped solder bumps. 相似文献