全文获取类型
收费全文 | 13648篇 |
免费 | 1743篇 |
国内免费 | 760篇 |
专业分类
电工技术 | 1652篇 |
综合类 | 1162篇 |
化学工业 | 1529篇 |
金属工艺 | 488篇 |
机械仪表 | 801篇 |
建筑科学 | 575篇 |
矿业工程 | 330篇 |
能源动力 | 285篇 |
轻工业 | 1560篇 |
水利工程 | 139篇 |
石油天然气 | 229篇 |
武器工业 | 81篇 |
无线电 | 3414篇 |
一般工业技术 | 1192篇 |
冶金工业 | 449篇 |
原子能技术 | 57篇 |
自动化技术 | 2208篇 |
出版年
2024年 | 46篇 |
2023年 | 162篇 |
2022年 | 325篇 |
2021年 | 351篇 |
2020年 | 437篇 |
2019年 | 403篇 |
2018年 | 382篇 |
2017年 | 589篇 |
2016年 | 631篇 |
2015年 | 645篇 |
2014年 | 996篇 |
2013年 | 843篇 |
2012年 | 1137篇 |
2011年 | 1181篇 |
2010年 | 888篇 |
2009年 | 778篇 |
2008年 | 689篇 |
2007年 | 707篇 |
2006年 | 677篇 |
2005年 | 526篇 |
2004年 | 435篇 |
2003年 | 585篇 |
2002年 | 605篇 |
2001年 | 596篇 |
2000年 | 409篇 |
1999年 | 314篇 |
1998年 | 189篇 |
1997年 | 165篇 |
1996年 | 109篇 |
1995年 | 82篇 |
1994年 | 62篇 |
1993年 | 31篇 |
1992年 | 31篇 |
1991年 | 28篇 |
1990年 | 31篇 |
1989年 | 19篇 |
1988年 | 15篇 |
1987年 | 12篇 |
1986年 | 7篇 |
1985年 | 4篇 |
1984年 | 3篇 |
1982年 | 3篇 |
1981年 | 3篇 |
1980年 | 2篇 |
1979年 | 2篇 |
1973年 | 2篇 |
1965年 | 3篇 |
1960年 | 1篇 |
1958年 | 2篇 |
1955年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 4 毫秒
71.
刘柯 《西安邮电学院学报》2009,14(5):96-99
本文主要针对目前多核处理器中核状态难以监控这一问题,分别从硬件和软件角度给出了解决方案,并通过具体的实现方法和试验说明了使用软件方法解决此问题的优越性。 相似文献
72.
This paper reports on the experimental investigation carried out to evaluate fractional dispersed phase holdup for a gas‐liquid mixture in a modified multi‐stage bubble column (with contraction and expansion disks), which has been conceived, designed and fabricated as a wet scrubber for control of air pollution; in addition it has versatile use as a gas‐liquid contactor in chemical process industries. A correlation developed for predicting fractional dispersed phase holdup has been found to be encouraging and highly significant from statistical analysis. 相似文献
73.
74.
75.
76.
本文提出一种基于神经网络的多效并流蒸发过程的模拟以及优化算法,并以一简单三效并流蒸发过程为例,详细阐述了神经网络模拟算法的具体步骤。该算法具有对初始值要求不高、收敛速度快,全局收敛性好的特点。 相似文献
77.
传统的具有功率因数校正(power factor correction,PFC)功能的DC输出LED驱动器需要在输出端用容值较大的电解电容来减小输出电流纹波。为解决电解电容的使用寿命短而造成驱动器寿命低于LED寿命的问题,采用一种新型的AC LED拓扑电路结构,理论分析了该拓扑电路结构以及参数的选取。由于该驱动器的输入电压和输出电压都是脉动的,驱动器的输入输出滤波可采用容值较小的薄膜电容,从而提高了驱动器的使用寿命。通过仿真和试验的结果表明,该拓扑电路结构是可行的,其参数的选取是正确的。 相似文献
78.
为解决多项目关键链管理问题对企业整体利益的影响,以多项目中各子项目工期总和的最小化为目标,提出"子关键链群"的概念。在单项目关键链管理的基础上,对项目间冲突资源的优先分配进行了分析研究,建立一套系统的分配规则,使得各子项目工期总和达到最小。同时,通过对项目间优先权的合理分配得出企业整体利益最大化的组合方案,实例验证,此方法可行、合理。 相似文献
79.
Yuhang Zhang Baojiu Chen Xizhen Zhang Xiangping Li Jinsu Zhang Sai Xu Xin Wang Yanqiu Zhang Li Wang Desheng Li Hai Lin 《Journal of the American Ceramic Society》2021,104(1):350-360
Lighting sources with full-color visible output are widely preferred in practical applications. In addition, modern lighting sources also tend to be intelligentized, and the intelligentization asks for smart luminescence materials. In this work, we attempt to develop novel full-color emitting material with temperature sensing and thermochromatic ability. To this end, the Cu2+ is successfully reduced to Cu+ which is incorporated into the germanate glasses. The glasses are prepared via a melt-quenching technique using graphite powders as reducing reagent. The supper-broadening of the excitation and the emission spectra of Cu+ in the germanate glasses are observed. Full-color emission is realized by introducing Tm3+ as co-dopant to provide the blue component in the spectra. The energy transfer behavior between Cu+ and Tm3+ is investigated, and it is found that these two luminescence centers are independently existent without energy transfer between them. The chromatic properties of the Cu+/Tm3+ co-doped glasses are tuned by Tm3+ concentration and excitation wavelength. The temperature sensing based on the fluorescence intensity ratio technique is demonstrated, and a constant sensitivity for the temperature detection is obtained. Moreover the thermochromatic property is also investigated, and it is found that the studied Cu+/Tm3+-doped glasses exhibit excellent thermochromatic performance. 相似文献
80.
Shuai Huang Lixin Yu Kangliang Peng Youjun Zhao Jindi Wang Mengmeng Shang 《Journal of the American Ceramic Society》2021,104(11):5848-5858
To enhance the display quality of light-emitting diodes (LEDs), it is of great significance to exploit green/yellow-emitting phosphors with narrow emission band, high quantum yield, and excellent color purity to satisfy the application. Herein, orthophosphate-based green/yellow-emitting Na3Tb(PO4)2:Ce3+/Eu2+ (NTPO:Ce3+/Eu2+) phosphors have been successfully synthesized by a facile solid-state reaction method. The absorption band of NTPO samples was extended to the near-ultraviolet region and the absorption efficiency was significantly improved owing to a highly efficient energy transfer from Ce3+/Eu2+ ion to Tb3+ ion in NTPO host certified by time-resolved PL spectra. Upon 300 nm excitation, the NTPO:Ce3+ is characterized by ultra-narrow-band green emission of Tb3+ with an absolute quantum yield of 94.5%. Unexpectedly, NTPO:Eu2+ emits bright yellow light with a color purity of 73% as a result of the blending of green light emission from Tb3+ and red light emission from Eu3+. The thermal stability has been improved by controlling the stoichiometric ratio of Na+. The prototype white LED used yellow-emitting NTPO:Eu2+ phosphor has higher color-rendering index (Ra = 83.5), lower correlated color temperature (CCT = 5206 K), and closer CIE color coordinates (0.338, 0.3187) to the standard white point at (0.333, 0.333) than that used green-emitting NTPO:Ce3+ phosphor, indicating the addition of the yellow light component improved the Ra of the trichromatic (RGB) materials. 相似文献