全文获取类型
收费全文 | 188121篇 |
免费 | 18767篇 |
国内免费 | 11406篇 |
专业分类
电工技术 | 15207篇 |
技术理论 | 8篇 |
综合类 | 15211篇 |
化学工业 | 26918篇 |
金属工艺 | 11229篇 |
机械仪表 | 12584篇 |
建筑科学 | 15512篇 |
矿业工程 | 6150篇 |
能源动力 | 5627篇 |
轻工业 | 14010篇 |
水利工程 | 4514篇 |
石油天然气 | 9389篇 |
武器工业 | 2126篇 |
无线电 | 23066篇 |
一般工业技术 | 19376篇 |
冶金工业 | 7728篇 |
原子能技术 | 2089篇 |
自动化技术 | 27550篇 |
出版年
2024年 | 910篇 |
2023年 | 3045篇 |
2022年 | 6039篇 |
2021年 | 8309篇 |
2020年 | 6238篇 |
2019年 | 4887篇 |
2018年 | 5458篇 |
2017年 | 6435篇 |
2016年 | 5585篇 |
2015年 | 8263篇 |
2014年 | 10440篇 |
2013年 | 12505篇 |
2012年 | 14319篇 |
2011年 | 14987篇 |
2010年 | 13741篇 |
2009年 | 13020篇 |
2008年 | 12853篇 |
2007年 | 12165篇 |
2006年 | 11145篇 |
2005年 | 8839篇 |
2004年 | 6140篇 |
2003年 | 5270篇 |
2002年 | 5009篇 |
2001年 | 4408篇 |
2000年 | 3671篇 |
1999年 | 3070篇 |
1998年 | 2118篇 |
1997年 | 1749篇 |
1996年 | 1645篇 |
1995年 | 1351篇 |
1994年 | 1145篇 |
1993年 | 734篇 |
1992年 | 591篇 |
1991年 | 444篇 |
1990年 | 371篇 |
1989年 | 305篇 |
1988年 | 223篇 |
1987年 | 150篇 |
1986年 | 134篇 |
1985年 | 76篇 |
1984年 | 58篇 |
1983年 | 41篇 |
1982年 | 60篇 |
1981年 | 62篇 |
1980年 | 55篇 |
1979年 | 35篇 |
1978年 | 20篇 |
1977年 | 20篇 |
1976年 | 22篇 |
1951年 | 15篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
本文分析了QC小组活动与企业文化的特点与共同点,提出开展QC小组活动与企业文化建设是互相促进,互相补充的,两者可以互相结合。 相似文献
72.
This paper presents an investigation on a single-mode-multimode-single-mode fiber structure. A one-way guided-mode propagation analysis for the circular symmetry waveguide is employed to model the light propagation and the approximated formulations are derived and evaluated concerning the accuracy. Phase conjunction of the multimode interference within the fiber structure is revealed. A simple way to predict and analyze the spectral response of the structure is presented through the space to wavelength mapping with the derived approximated formulations. The prediction of spectral response is verified numerically and experimentally. 相似文献
73.
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
74.
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
75.
76.
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
77.
78.
79.
The main difficulty with EM algorithm for mixture model concerns the number of components, say g. This is the question of model selection, and the EM algorithm itself could not estimate g. On the contrary, the algorithm requires g to be specified before the remaining parameters can be estimated. To solve this problem, a new algorithm, which is called stepwise split-and-merge EM (SSMEM) algorithm, is proposed. The SSMEM algorithm alternately splits and merges components, estimating g and other parameters of components simultaneously. Also, two novel criteria are introduced to efficiently select the components for split or merge. Experimental results on simulated and real data demonstrate the effectivity of the proposed algorithm. 相似文献
80.
LaNiO3 was synthesized by sol-gel method in which lanthanum nitrate and nickel nitrate were used as start materials and citric acid was used as complex for gel formation.The precursor was dried and subsequently heated at elevated temperature to form the desired product.XRD analysis shows that pure LaNiO3 was synthesized.Electrical conductivity and electrochemical performance of the material were tested.The electrical conductivity decreases from 34.5that there are current peaks in the curve, which is the evidence of the electrochemical activity of LaNiO3. 相似文献