全文获取类型
收费全文 | 7829篇 |
免费 | 831篇 |
国内免费 | 490篇 |
学科分类
工业技术 | 9150篇 |
出版年
2024年 | 21篇 |
2023年 | 78篇 |
2022年 | 160篇 |
2021年 | 219篇 |
2020年 | 254篇 |
2019年 | 206篇 |
2018年 | 184篇 |
2017年 | 302篇 |
2016年 | 304篇 |
2015年 | 312篇 |
2014年 | 466篇 |
2013年 | 542篇 |
2012年 | 549篇 |
2011年 | 601篇 |
2010年 | 431篇 |
2009年 | 519篇 |
2008年 | 444篇 |
2007年 | 504篇 |
2006年 | 438篇 |
2005年 | 382篇 |
2004年 | 313篇 |
2003年 | 351篇 |
2002年 | 210篇 |
2001年 | 209篇 |
2000年 | 208篇 |
1999年 | 174篇 |
1998年 | 117篇 |
1997年 | 91篇 |
1996年 | 84篇 |
1995年 | 99篇 |
1994年 | 78篇 |
1993年 | 64篇 |
1992年 | 47篇 |
1991年 | 24篇 |
1990年 | 39篇 |
1989年 | 26篇 |
1988年 | 21篇 |
1987年 | 11篇 |
1986年 | 6篇 |
1985年 | 11篇 |
1984年 | 9篇 |
1983年 | 7篇 |
1982年 | 9篇 |
1981年 | 3篇 |
1980年 | 2篇 |
1979年 | 2篇 |
1978年 | 2篇 |
1975年 | 3篇 |
1959年 | 2篇 |
1951年 | 1篇 |
排序方式: 共有9150条查询结果,搜索用时 17 毫秒
1.
Many models of spoken word recognition posit the existence of lexical and sublexical representations, with excitatory and inhibitory mechanisms used to affect the activation levels of such representations. Bottom-up evidence provides excitatory input, and inhibition from phonetically similar representations leads to lexical competition. In such a system, long words should produce stronger lexical activation than short words, for 2 reasons: Long words provide more bottom-up evidence than short words, and short words are subject to greater inhibition due to the existence of more similar words. Four experiments provide evidence for this view. In addition, reaction-time-based partitioning of the data shows that long words generate greater activation that is available both earlier and for a longer time than is the case for short words. As a result, lexical influences on phoneme identification are extremely robust for long words but are quite fragile and condition-dependent for short words. Models of word recognition must consider words of all lengths to capture the true dynamics of lexical activation. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
2.
3.
本文报导了最近研制成功的用于提高国产氩离子激光器相干长度的相干扩展器。利用这种基于F-P理论的相干扩展器可以使国产氩离子激光器的相干长度由不足5cm一下提高到m的量级,功率损耗在25%~40%之间,有着很好的应用前景。 相似文献
4.
A Novel Segmentation and Feedback Model for Resolving Contention in Optical Burst Switching 总被引:2,自引:0,他引:2
A novel segmentation and feedback model (SFM) applied to resolve contention is proposed. Simulation and performance analyses show that the SFM effectively avoids contentions in optical burst switching (OBS). The long delay time of deflection routing and the immature technology of wavelength converters and optical buffers are not deployed in the SFM. The SFM does not only realize fast switching but also allows preemption by higher priority bursts. 相似文献
5.
6.
7.
本文通过对某液压挖掘机工作装置实验样本长度的研究,详细讨论了样本长度的确定方法,重点分析了趋势曲线拟合法,提出了样本长度精度区间分析的方法,并在处理大量实验数据的基础上,从载荷分布及寿命估算的角度做了实际的验证.编制了应用程序,使样本长度确定至寿命估算整个过程程序化. 相似文献
8.
L. O. Aizenberg E. A. Khvoles 《Power Technology and Engineering (formerly Hydrotechnical Construction)》2007,41(6):379-382
Problems with the construction of transmission lines above a forest are examined. Construction of lines above standing timber
makes it possible to shorten the length of the route, eliminate the clearing of a continuous swath along the line, and reduce
the volume of in-service work. To implement this solution, it is necessary to introduce changes and supplements to existing
regulatory technical documents.
__________
Translated from élektricheskie Stantsii, No. 10, October 2007, pp. 48–51. 相似文献
9.
10.
The syntheses of polyenynes as model compounds for poly(diacetylene)s (PDAs) are described. Variation of properties (UV–VIS, Raman, NMR and bond geometries) as a function of the chain length was investigated. After extrapolation to infinite chain length these data were compared to those for PDAs. From UV–VIS spectra a value of λ = 551 nm (2.25 eV) was calculated corresponding to the electronic transition of a single polyenyne chain. This energy is located at the low energy end of a yellow PDA solution spectrum. From Raman scattering v(C?C) = 2108–2128 cm?1 and v(C?C) = 1505–1532 cm?1 were calculated after extrapolation. Similarly sp-C13C NMR data yielded a shift of δ = 100 ppm. These data are almost identical to data known for yellow PDA solutions. Bond geometries are almost identical to those of poly(diacetylene)s and theoretical data. 相似文献