全文获取类型
收费全文 | 5740篇 |
免费 | 419篇 |
国内免费 | 283篇 |
专业分类
电工技术 | 67篇 |
综合类 | 173篇 |
化学工业 | 1574篇 |
金属工艺 | 348篇 |
机械仪表 | 275篇 |
建筑科学 | 21篇 |
矿业工程 | 36篇 |
能源动力 | 175篇 |
轻工业 | 399篇 |
水利工程 | 10篇 |
石油天然气 | 76篇 |
武器工业 | 11篇 |
无线电 | 1419篇 |
一般工业技术 | 1543篇 |
冶金工业 | 76篇 |
原子能技术 | 109篇 |
自动化技术 | 130篇 |
出版年
2024年 | 21篇 |
2023年 | 150篇 |
2022年 | 155篇 |
2021年 | 186篇 |
2020年 | 192篇 |
2019年 | 197篇 |
2018年 | 191篇 |
2017年 | 217篇 |
2016年 | 229篇 |
2015年 | 180篇 |
2014年 | 294篇 |
2013年 | 350篇 |
2012年 | 317篇 |
2011年 | 495篇 |
2010年 | 290篇 |
2009年 | 359篇 |
2008年 | 287篇 |
2007年 | 295篇 |
2006年 | 302篇 |
2005年 | 226篇 |
2004年 | 237篇 |
2003年 | 198篇 |
2002年 | 185篇 |
2001年 | 143篇 |
2000年 | 99篇 |
1999年 | 77篇 |
1998年 | 72篇 |
1997年 | 62篇 |
1996年 | 62篇 |
1995年 | 73篇 |
1994年 | 67篇 |
1993年 | 46篇 |
1992年 | 43篇 |
1991年 | 32篇 |
1990年 | 32篇 |
1989年 | 28篇 |
1988年 | 13篇 |
1987年 | 6篇 |
1986年 | 6篇 |
1985年 | 4篇 |
1984年 | 6篇 |
1983年 | 2篇 |
1982年 | 7篇 |
1981年 | 2篇 |
1980年 | 3篇 |
1978年 | 1篇 |
1973年 | 2篇 |
1951年 | 1篇 |
排序方式: 共有6442条查询结果,搜索用时 0 毫秒
1.
We demonstrate that alkali-halide salts, particularly potassium bromide, can reduce the photothermal emission (PTE) from single walled carbon nanotubes (SWNT). PTE is a prominent spectral feature in Raman spectroscopy when a near infrared laser is used to analyze a dark colored sample. We subsequently show that trapping salts inside SWNT and coating SWNT with the salt has a more pronounced impact on not only reducing PTE, but also enhancing the intensity of the Raman spectral features. The effect, which we have called nanotube enhanced Raman spectroscopy (NERS), has differences and similarities to the widely studied surface enhanced Raman spectroscopy (SERS). 相似文献
2.
G. Martinez 《Journal of Low Temperature Physics》2003,133(1-2):61-95
High magnetic fields are one of the most powerful tools available to scientists for the study, modification and control of matter. This includes the knowledge on correlations effects, interaction mechanisms, structural information and understanding of mesoscopic effects. In this context, a review of recent scientific achievements at the Grenoble High Magnetic Laboratory is given to illustrate, on specific examples, the power of the Magnetic Field probe. 相似文献
3.
Absorption spectra of several types of diesel fuel are studied experimentally. Index of refraction of these fuels is calculated using subtractive Kramers-Krönig analysis. The ageing process of fuels is simulated by prolonged boiling. Radiative properties of diesel fuel droplets are calculated using the Mie theory and a simplified approach, based on approximations of absorption and scattering efficiency factors. It is pointed out that the accuracy of the simplified approach is sufficient for practical applications in the visible and infrared ranges, for various types of diesel fuel, and for droplet radii in the range from 5 to 50 μm. The monodisperse approximation is shown to be applicable for the analysis of infrared radiative properties of realistic polydisperse diesel fuel sprays. 相似文献
4.
5.
6.
The structural properties and hydrogen bonding of undoped and phosphorous doped polycrystalline silicon produced by step-by-step laser dehydrogenation and crystallization technique were investigated using Raman spectroscopy and hydrogen effusion measurements. At low laser fluences, EL, a two-layer system is created. This is accompanied by the change in hydrogen bonding. The intensity of the Si–H vibration mode at 2000 decreases faster than the one at 2100 cm−1. This is even more pronounced in phosphorous-doped specimens. The laser crystallization results in an increase of the hydrogen binding energy by approximately 0.2–0.3 eV compared to the amorphous starting materials. 相似文献
7.
WANGYu-tian LIUZhan-wei HOUPei-guo SHANWei 《半导体光子学与技术》2004,10(3):199-202
The distributed optical fiber sensing technology is overviewed, which is based on Raman scattering light theory. Basic operation principle, structure, system characteristics and signal processing are discussed. This structure and method of the signal processing possess of certain spatial resolution, hence will ensure the practicability of system. 相似文献
8.
9.
Herbert S. Bennett 《Journal of research of the National Institute of Standards and Technology》2007,112(4):209-221
In this paper, we present the theory for calculating Raman line shapes as functions of the Fermi energy and finite temperatures in zinc blende, n-type GaAs for donor densities between 1016 cm−3 and 1019 cm−3. Compared to other theories, this theory is unique in two respects: 1) the many-body effects are treated self-consistently and 2) the theory is valid at room temperature for arbitrary values of the ratio R = (Q2/α), where Q is the magnitude of the normalized wave vector and α is the normalized frequency used in the Raman measurements. These calculations solve the charge neutrality equation self-consistently for a two-band model of GaAs at 300 K that includes the effects of high carrier concentrations and dopant densities on the perturbed densities of states used to calculate the Fermi energy as a function of temperature. The results are then applied to obtain the carrier concentrations from Fermi energies in the context of line shapes in Raman spectra due to the coupling between longitudinal optical phonons and plasmons. Raman measurements have been proposed as a non-destructive method for wafer acceptance tests of carrier density in semiconductor epilayers. The interpretation of Raman spectra to determine the majority electron density in n-type semiconductors requires an interdisciplinary effort involving experiments, theory, and computer-based simulations and visualizations of the theoretical calculations. 相似文献
10.