全文获取类型
收费全文 | 116406篇 |
免费 | 10481篇 |
国内免费 | 5772篇 |
专业分类
电工技术 | 6437篇 |
技术理论 | 11篇 |
综合类 | 7897篇 |
化学工业 | 19293篇 |
金属工艺 | 6501篇 |
机械仪表 | 7442篇 |
建筑科学 | 9286篇 |
矿业工程 | 3239篇 |
能源动力 | 3170篇 |
轻工业 | 9446篇 |
水利工程 | 2198篇 |
石油天然气 | 6203篇 |
武器工业 | 994篇 |
无线电 | 13644篇 |
一般工业技术 | 14248篇 |
冶金工业 | 5222篇 |
原子能技术 | 1347篇 |
自动化技术 | 16081篇 |
出版年
2024年 | 246篇 |
2023年 | 1786篇 |
2022年 | 2894篇 |
2021年 | 4332篇 |
2020年 | 3426篇 |
2019年 | 3015篇 |
2018年 | 3347篇 |
2017年 | 3703篇 |
2016年 | 3440篇 |
2015年 | 4677篇 |
2014年 | 5836篇 |
2013年 | 7070篇 |
2012年 | 7984篇 |
2011年 | 8625篇 |
2010年 | 7688篇 |
2009年 | 7383篇 |
2008年 | 7176篇 |
2007年 | 6945篇 |
2006年 | 6856篇 |
2005年 | 5816篇 |
2004年 | 4092篇 |
2003年 | 3378篇 |
2002年 | 3227篇 |
2001年 | 2848篇 |
2000年 | 2584篇 |
1999年 | 2627篇 |
1998年 | 2179篇 |
1997年 | 1783篇 |
1996年 | 1645篇 |
1995年 | 1276篇 |
1994年 | 1187篇 |
1993年 | 849篇 |
1992年 | 644篇 |
1991年 | 515篇 |
1990年 | 383篇 |
1989年 | 310篇 |
1988年 | 263篇 |
1987年 | 165篇 |
1986年 | 122篇 |
1985年 | 81篇 |
1984年 | 43篇 |
1983年 | 39篇 |
1982年 | 55篇 |
1981年 | 23篇 |
1980年 | 19篇 |
1979年 | 16篇 |
1978年 | 10篇 |
1977年 | 10篇 |
1976年 | 14篇 |
1975年 | 9篇 |
排序方式: 共有10000条查询结果,搜索用时 359 毫秒
61.
62.
Journal of Computer Science and Technology - DOACROSS loops are significant parts in many important scientific and engineering applications, which are generally exploited pipeline/wave-front... 相似文献
63.
Wei-Li Xie Xiao-Dong Zhang Wen-Hui Liu Qi Xie Guang-Wu Wen Xiao-Xiao Huang Jian-Dong Zhu Fei-Xiang Ma 《稀有金属(英文版)》2019,(3)
SiC nano wires were fabricated on the silicon substrate dipped with a layer of Ni catalyst at 900 ℃ by gas pressure annealing processing. The morphologies and crystal structures were determined by scanning electron microscopy(SEM), transmission electron microscopy(TEM)and X-ray diffraction(XRD). The results show that the assynthesized nanowires are β-SiC single crystalline with diameter range of 50-100 nm, and length of tens of micron by directly annealing at 900 ℃. The SiC nano wires grow along the [111] direction with highly uniform morphology. And the possible growth mechanism of SiC nano wires is proposed.The present work provides an efficient strategy for the production of high-quality SiC nano wires. 相似文献
64.
Qiang Liu Xinyu Mao Xiaoying Li Penghui Chen Xin Liu Ziyu Liu Danyang Zhu Haohong Chen Tengfei Xie Jiang Li 《Journal of the American Ceramic Society》2021,104(10):4927-4931
0.5 at.% Cr:ZnGa2O4 precursor was synthesized by the co-precipitation method with nitrates as raw materials, using ammonium carbonate as the precipitant. Low-agglomerated Cr:ZnGa2O4 powders with an average particle size of 43 nm were obtained by calcining the precursor at 900℃ for 4 h. Using the powders as starting materials, 0.5 at.% Cr:ZnGa2O4 ceramics with an average grain size of about 515 nm were prepared by presintering at 1150℃ for 5 h in air and HIP post-treatment at 1100℃ for 3 h under 200 MPa Ar. The in-line transmittance of 0.5 at.% Cr:ZnGa2O4 ceramics with a thickness of 1.3 mm reaches 59.5% at the wavelength of 700 nm. The Cr:ZnGa2O4 ceramics can be effectively excited by visible light and produce persistent luminescence at 700 nm. For Cr:ZnGa2O4 transparent ceramics, the brightness of afterglow was larger than 0.32 mcd/m2 after 30 min, which is far superior to that of Cr:ZnGa2O4 persistent luminescence powders. 相似文献
65.
66.
为了提高花粉浓度预报的准确率,解决现有花粉浓度预报准确率不高的问题,提出了一种基于粒子群优化(PSO)算法和支持向量机(SVM)的花粉浓度预报模型。首先,综合考虑气温、气温日较差、相对湿度、降水量、风力、日照时数等多种气象要素,选择与花粉浓度相关性较强的气象要素构成特征向量;其次,利用特征向量与花粉浓度数据建立SVM预测模型,并使用PSO算法找出最优参数;然后利用最优参数优化花粉浓度预测模型;最后,使用优化后的模型对花粉未来24 h浓度进行预测,并与未优化的SVM、多元线性回归法(MLR)、反向神经网络(BPNN)作对比。此外使用优化后的模型对某市南郊观象台和密云两个站点进行逐日花粉浓度预测。实验结果表明,相比其他预报方法,所提方法能有效提高花粉浓度未来24 h预测精度,并具有较高的泛化能力。 相似文献
67.
Metallurgical and Materials Transactions B - To investigate the closure behavior of internal porosity (also referred to as internal void) in continuous casting bloom during heavy reduction (HR) and... 相似文献
68.
69.
Deep Integration of Innovation and Entrepreneurship (InE) Education in Chinese University Classrooms
Recently, InE has been regarded as a popular education strategy in Chinese universities. However, problems have been exposed in the adoption of InE, for example, in InE courses and competitions. The purpose of this paper is to provide a possible solution to the problems, which is to organize effective InE courses by integrating InE with Inter-Course-level Problem-Based Learning (ICPBL). A detailed case is demonstrated by an ICPBL elective course design with deep integration of InE in the teaching, learning, and assessments. This paper contributes to a new curriculum design for promoting InE education in practically for Chinese universities. 相似文献
70.
The Journal of Supercomputing - Cyber physical system (CPS) is consisting of two interdependent networks, i.e., a cyber network embedding into a physical network. Although interdependence makes the... 相似文献