全文获取类型
收费全文 | 14878篇 |
免费 | 1603篇 |
国内免费 | 901篇 |
专业分类
电工技术 | 1087篇 |
综合类 | 1297篇 |
化学工业 | 2707篇 |
金属工艺 | 749篇 |
机械仪表 | 892篇 |
建筑科学 | 1004篇 |
矿业工程 | 397篇 |
能源动力 | 674篇 |
轻工业 | 1389篇 |
水利工程 | 348篇 |
石油天然气 | 474篇 |
武器工业 | 99篇 |
无线电 | 1786篇 |
一般工业技术 | 1668篇 |
冶金工业 | 590篇 |
原子能技术 | 218篇 |
自动化技术 | 2003篇 |
出版年
2024年 | 43篇 |
2023年 | 165篇 |
2022年 | 374篇 |
2021年 | 495篇 |
2020年 | 366篇 |
2019年 | 383篇 |
2018年 | 390篇 |
2017年 | 421篇 |
2016年 | 438篇 |
2015年 | 622篇 |
2014年 | 763篇 |
2013年 | 933篇 |
2012年 | 1043篇 |
2011年 | 1042篇 |
2010年 | 993篇 |
2009年 | 911篇 |
2008年 | 915篇 |
2007年 | 884篇 |
2006年 | 822篇 |
2005年 | 675篇 |
2004年 | 637篇 |
2003年 | 734篇 |
2002年 | 1009篇 |
2001年 | 826篇 |
2000年 | 442篇 |
1999年 | 301篇 |
1998年 | 124篇 |
1997年 | 143篇 |
1996年 | 115篇 |
1995年 | 86篇 |
1994年 | 40篇 |
1993年 | 51篇 |
1992年 | 34篇 |
1991年 | 28篇 |
1990年 | 19篇 |
1989年 | 28篇 |
1988年 | 13篇 |
1987年 | 11篇 |
1986年 | 6篇 |
1985年 | 11篇 |
1983年 | 3篇 |
1982年 | 8篇 |
1981年 | 5篇 |
1980年 | 5篇 |
1978年 | 2篇 |
1977年 | 4篇 |
1972年 | 2篇 |
1966年 | 2篇 |
1959年 | 3篇 |
1951年 | 3篇 |
排序方式: 共有10000条查询结果,搜索用时 9 毫秒
21.
Learning and memory of novel spatial configurations aids behaviors such as visual search through an implicit process called contextual cuing (M. M. Chun & Y. Jiang, 1998). The present study provides rigorous tests of the implicit nature of contextual cuing. Experiment 1 used a recognition test that closely matched the learning task, confirming that memory traces of predictive spatial context were not accessible to conscious retrieval. Experiment 2 gave explicit instructions to encode visual context during learning, but learning was not improved and conscious memory remained undetectable. Experiment 3 illustrates that memory traces for spatial context may persist for at least 1 week, suggesting a long-term component of contextual cuing. These experiments indicate that the learning and memory of spatial context in the contextual cuing task are indeed implicit. The results have implications for understanding the neural substrate of spatial contextual learning, which may depend on an intact medial temporal lobe system that includes the hippocampus (M. M. Chun & E. A. Phelps, 1999). (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
22.
23.
24.
25.
卡通是大众所钟爱的一种艺术形式,在这样一个文化多元而开放的时代,人们推崇的卡通形象无论从造型、个性与角色背景方面都呈现出显著的"草根化"趋势,而这种趋势已成为推动卡通文化流动和发展的原动力之一。 相似文献
26.
Chun‐Wei Liu Chi‐Hung Lee Shih‐Chieh Lin 《Journal of the Society for Information Display》2012,20(12):646-652
This study proposes a roll‐to‐roll process‐based sub‐wavelength grating, which is attached on a light bar to turn the side‐lit red/green/blue (620, 520, and 450 nm) incident rays into a uniformly and normally output white light with high illuminance from the light bar's surface. On the basis of the rigorous coupling wave analysis, the relationship between the first‐order transmission/reflection efficiency and the pitch of the gratings with different shapes was analyzed. The optimal design can effectively reduce the coupling length and enhance the white color balance for display applications. 相似文献
27.
Register allocation for write activity minimization on non-volatile main memory for embedded systems
Yazhi Huang Author VitaeTiantian Liu Author Vitae Chun Jason XueAuthor Vitae 《Journal of Systems Architecture》2012,58(1):13-23
Non-volatile memories are good candidates for DRAM replacement as main memory in embedded systems and they have many desirable characteristics. Nevertheless, the disadvantages of non-volatile memory co-exist with its advantages. First, the lifetime of some of the non-volatile memories is limited by the number of erase operations. Second, read and write operations have asymmetric speed or power consumption in non-volatile memory. This paper focuses on the embedded systems using non-volatile memory as main memory. We propose register allocation technique with re-computation to reduce the number of store instructions. When non-volatile memory is applied as the main memory, reducing store instructions will reduce write activities on non-volatile memory. To re-compute the spills effectively during register allocation, a novel potential spill selection strategy is proposed. During this process, live range splitting is utilized to split certain long live ranges such that they are more likely to be assigned into registers. In addition, techniques for re-computation overhead reduction is proposed on systems with multiple functional units. With the proposed approach, the lifetime of non-volatile memory is extended accordingly. The experimental results demonstrate that the proposed technique can efficiently reduce the number of store instructions on systems with non-volatile memory by 33% on average. 相似文献
28.
Insulator-based dielectrophoresis (iDEP) has been successfully used for on-chip manipulations of biological samples. Despite
its effectiveness, iDEP typically requires high DC voltages to achieve sufficient electric field; this is mainly due to the
coupled phenomena among linear electrokinetics: electroosmosis (EO) and electrophoresis (EP) and nonlinear electrokinetics:
dielectrophoresis (DEP). This paper presents a microfluidic technique using DC-offset AC electric field for electrokinetic
concentration of particles and cells by repulsive iDEP. This technique introduces AC electric field for producing iDEP which
is decoupled from electroosmosis (EO) and electrophoresis (EP). The repulsive iDEP is generated in a PDMS tapered contraction
channel that induces non-uniform electric field. The benefits of introducing AC electric field component are threefold: (i)
it contributes to DEP force acting on particles, (ii) it suppresses EO flow and (iii) it does not cause any EP motion. As
a result, the required DC field component that is mainly used to transport particles on the basis of EO and EP can be significantly
reduced. Experimental results supported by numerical simulations showed that the total DC-offset AC electric field strength
required to concentrate 15-μm particles is significantly reduced up to 85.9% as compared to using sole DC electric field.
Parametric experimental studies showed that the higher buffer concentration, larger particle size and higher ratio of AC-to-DC
electric field are favorable for particle concentration. In addition, the proposed technique was demonstrated for concentration
of yeast cells. 相似文献
29.
30.