全文获取类型
收费全文 | 188226篇 |
免费 | 15941篇 |
国内免费 | 8436篇 |
专业分类
电工技术 | 11466篇 |
技术理论 | 13篇 |
综合类 | 11657篇 |
化学工业 | 31121篇 |
金属工艺 | 10050篇 |
机械仪表 | 11416篇 |
建筑科学 | 14241篇 |
矿业工程 | 5449篇 |
能源动力 | 5506篇 |
轻工业 | 13115篇 |
水利工程 | 3344篇 |
石油天然气 | 10746篇 |
武器工业 | 1404篇 |
无线电 | 22029篇 |
一般工业技术 | 23145篇 |
冶金工业 | 10663篇 |
原子能技术 | 2048篇 |
自动化技术 | 25190篇 |
出版年
2024年 | 904篇 |
2023年 | 3457篇 |
2022年 | 6435篇 |
2021年 | 8638篇 |
2020年 | 6495篇 |
2019年 | 5184篇 |
2018年 | 5894篇 |
2017年 | 6560篇 |
2016年 | 5894篇 |
2015年 | 7740篇 |
2014年 | 9634篇 |
2013年 | 11855篇 |
2012年 | 12620篇 |
2011年 | 13386篇 |
2010年 | 11350篇 |
2009年 | 10774篇 |
2008年 | 10325篇 |
2007年 | 9571篇 |
2006年 | 9726篇 |
2005年 | 8319篇 |
2004年 | 5618篇 |
2003年 | 4761篇 |
2002年 | 4249篇 |
2001年 | 3772篇 |
2000年 | 3706篇 |
1999年 | 4324篇 |
1998年 | 3611篇 |
1997年 | 3082篇 |
1996年 | 2895篇 |
1995年 | 2379篇 |
1994年 | 1931篇 |
1993年 | 1424篇 |
1992年 | 1181篇 |
1991年 | 869篇 |
1990年 | 657篇 |
1989年 | 574篇 |
1988年 | 470篇 |
1987年 | 353篇 |
1986年 | 307篇 |
1985年 | 233篇 |
1984年 | 219篇 |
1983年 | 183篇 |
1982年 | 148篇 |
1981年 | 144篇 |
1980年 | 122篇 |
1979年 | 86篇 |
1978年 | 100篇 |
1977年 | 76篇 |
1976年 | 74篇 |
1975年 | 61篇 |
排序方式: 共有10000条查询结果,搜索用时 8 毫秒
51.
52.
Gang Chen Zhonghua Yang Chor Ping Low 《Industrial Informatics, IEEE Transactions on》2006,2(4):269-280
In this paper, we address agent coordination from a dynamic systems perspective and propose a dynamic coordination model, which is inspired by biological metabolic systems. A new coordination mechanism through dynamic local adjustment (CDLA) is presented, and coordination is achieved when every agent utilizes explicitly the global system dynamics and performs iteratively a dynamic local adjustment procedure. The CDLA mechanism is investigated in an example multiagent shop floor system. The results show that the example manufacturing process is well-coordinated and the coordination approach is practically applicable and effective 相似文献
53.
54.
One hypothesis for the transcontinental and intra-Great Lakes basin transfer of round gobies (Neogobius melanostomus) has been that round gobies were pumped into the ballast water of ships. During June 2005 in Lake Erie, we obtained evidence of a vertical migration of round goby larvae, when we collected 167 round goby larvae in surface ichthyoplankton net tows at night and zero during day. These results complemented similar findings from the Muskegon River estuary of Lake Michigan during 2003 and 2004, documenting diel vertical migration for the first time in larval round gobies. We suggest vertical migration behavior may have allowed larval round gobies to be transported to and within the Great Lakes via ballast water and dispersed in the Great Lakes via advection of 6.5–8.5-mm long larvae at the surface. Based on our results, if ballast water was only taken on near the surface during daylight hours from May through September when larval round gobies were present, it would have mitigated the spread of round gobies throughout the Great Lakes. 相似文献
55.
A segmentation-based fine-grained peer sharing technique for delivering large media files in content distribution networks 总被引:1,自引:0,他引:1
Zongming Fei Mengkun Yang 《Multimedia, IEEE Transactions on》2006,8(4):821-829
Delivering large media files over the Internet is a challenging task because it has some unique features that are different from delivering conventional Web documents. In this paper, we propose a fine-grained peer sharing technique for dealing with the problem in the context of content distribution networks. The key difference of the technique from conventional peer-to-peer systems is that the unit of peer sharing is not a complete media file, but at a finer granularity. By doing so, we improve the flexibility of replica servers for handling client requests. We analyze the storage requirement at replica servers and design a scheduling algorithm to coordinate the delivery process from multiple replica servers to a client. Our simulations show that the fine-grained peer sharing approach can reduce the initial latency of clients and the rejection rate of the system significantly over a simple peer sharing method. 相似文献
56.
Yu Yang Hugo Bender Kai Arstila Bart Swinnen Bert Verlinden Ingrid De Wolf 《Microelectronics Reliability》2008,48(8-9):1517-1520
Focused ion beam (FIB) and nano-probing were applied for failure analysis of three-dimensional stacked circuits with copper through-silicon-vias between the stacked chips. The failure analysis was done after high temperature storage and thermal cycling tests. Passive voltage contrast in FIB allowed to pinpoint the open sites. FIB cross-sections showed the presence of opens at the bottom of the copper vias. The failure cause was suspected to be an interlayer particle, which was confirmed by optical profilometry. Nano-probing was used on another sample to pinpoint the failure location through the measurement of the local resistance within the daisy chains. The failure was traced out to be related with surface contamination. 相似文献
57.
La doping effects on intergrowth Bi2WO6–Bi3TiNbO9 ferroelectric ceramics were studied by X-ray diffraction, electron probe microanalysis and dielectric spectroscopy. It was found that the La3+ distribution, ferroelectric phase transition and dielectric relaxation behavior are apparently affected by La doping. With increasing La3+ content, the site of dopant ion varies, the grain growth of Bi5TiNbWO15 is restrained, the Curie temperature is reduced and broadened. Furthermore, two dielectric relaxation loss peaks were observed both in temperature and frequency spectra. The calculated relaxation parameters revealed the oxygen vacancy related to the relaxation process. 相似文献
58.
59.
Hyun-Chul Kim Author VitaeDaijin KimAuthor Vitae Sung Yang Bang Author Vitae 《Pattern recognition》2003,36(5):1095-1105
Linear discriminant analysis (LDA) is a data discrimination technique that seeks transformation to maximize the ratio of the between-class scatter and the within-class scatter. While it has been successfully applied to several applications, it has two limitations, both concerning the underfitting problem. First, it fails to discriminate data with complex distributions since all data in each class are assumed to be distributed in the Gaussian manner. Second, it can lose class-wise information, since it produces only one transformation over the entire range of classes. We propose three extensions of LDA to overcome the above problems. The first extension overcomes the first problem by modelling the within-class scatter using a PCA mixture model that can represent more complex distribution. The second extension overcomes the second problem by taking different transformation for each class in order to provide class-wise features. The third extension combines these two modifications by representing each class in terms of the PCA mixture model and taking different transformation for each mixture component. It is shown that all our proposed extensions of LDA outperform LDA concerning classification errors for synthetic data classification, hand-written digit recognition, and alphabet recognition. 相似文献
60.
Jiashi Yang 《International Journal of Fracture》2004,127(1):L111-L116
An anti-plane, semi-infinite crack in polarized ceramics is analyzed using the theory of elastic dielectrics with electric
field gradient. The effects of electric field gradient on electromechanical fields around the crack is examined. 相似文献