全文获取类型
收费全文 | 211085篇 |
免费 | 24567篇 |
国内免费 | 15981篇 |
专业分类
电工技术 | 18964篇 |
技术理论 | 4篇 |
综合类 | 22019篇 |
化学工业 | 25886篇 |
金属工艺 | 14395篇 |
机械仪表 | 15490篇 |
建筑科学 | 16280篇 |
矿业工程 | 8847篇 |
能源动力 | 5576篇 |
轻工业 | 23436篇 |
水利工程 | 6768篇 |
石油天然气 | 8408篇 |
武器工业 | 3287篇 |
无线电 | 22701篇 |
一般工业技术 | 17510篇 |
冶金工业 | 8454篇 |
原子能技术 | 3399篇 |
自动化技术 | 30209篇 |
出版年
2024年 | 1328篇 |
2023年 | 3520篇 |
2022年 | 8174篇 |
2021年 | 10567篇 |
2020年 | 7857篇 |
2019年 | 5337篇 |
2018年 | 5967篇 |
2017年 | 7177篇 |
2016年 | 6149篇 |
2015年 | 9915篇 |
2014年 | 12350篇 |
2013年 | 14252篇 |
2012年 | 17436篇 |
2011年 | 18364篇 |
2010年 | 17323篇 |
2009年 | 16631篇 |
2008年 | 17082篇 |
2007年 | 16220篇 |
2006年 | 13938篇 |
2005年 | 11112篇 |
2004年 | 8048篇 |
2003年 | 5359篇 |
2002年 | 4952篇 |
2001年 | 4387篇 |
2000年 | 3552篇 |
1999年 | 1498篇 |
1998年 | 607篇 |
1997年 | 452篇 |
1996年 | 376篇 |
1995年 | 339篇 |
1994年 | 254篇 |
1993年 | 203篇 |
1992年 | 160篇 |
1991年 | 110篇 |
1990年 | 113篇 |
1989年 | 92篇 |
1988年 | 61篇 |
1987年 | 57篇 |
1986年 | 40篇 |
1985年 | 23篇 |
1984年 | 21篇 |
1983年 | 23篇 |
1982年 | 16篇 |
1981年 | 27篇 |
1980年 | 55篇 |
1979年 | 39篇 |
1977年 | 1篇 |
1974年 | 1篇 |
1959年 | 34篇 |
1951年 | 34篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
51.
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
52.
赵莉芳 《硫磷设计与粉体工程》2015,(2):24-27,11
根据以往的工程设计经验,从实用的角度出发,针对灰库设计中在工艺布置、设备选型及楼面标高的确定、设备及仪表检修等需要考虑的几个细节问题上,进行了总结整理以共同探讨。 相似文献
53.
54.
ZHAO Pengfei TIAN Yuming LIU Aiping KONG Xiangchen CHAI Yuesheng LI Zhangang BAI Pinbo 《中国耐火材料》2015,(2):36-41
Based on the needs of the market,a new 52 MPa medium-density and high-strength ceramic proppant was prepared by adopting third grade bauxite and clay as raw materials and using the solid phase sintering method,and the effect of the firing temperature on the microstructure,phase composition and mechanical properties of the ceramic proppant was studied. The broken resistance mechanism of this ceramic proppant was also discussed. The results show that the main phases of the prepared ceramic proppant are mullite and corundum; the broken rates are 3. 92% and 7. 21% under 52 MPa and69 MPa,respectively. 相似文献
55.
56.
Yong Pan Chen Zhu Wen Bin Zeng Pei Fu Chi Chen Bao Ming Xu Zhong Feng Gao 《Chembiochem : a European journal of chemical biology》2021,22(24):3431-3436
Rapid and sensitive point-of-care testing (POCT) is an extremely critical mission in practical applications, especially for rigorous military medicine, home health care, and in the third world. Here, we report a visual POCT method for adenosine triphosphate (ATP) detection based on Taylor rising in the corner of quadratic geometries between two rod surfaces. We discuss the principle of Taylor rising, demonstrating that it is significantly influenced by contact angle, surface tension, and density of the sample, which are controlled by ATP-dependent rolling circle amplification (RCA). In the presence of ATP, RCA reaction effectively suppresses Taylor-rising behavior, due to the increased contact angle, density, and decreased surface tension. Without addition of ATP, untriggered RCA reaction is favorable for Taylor rising, resulting in a significant height. With this proposed method, visual sensitive detection of ATP without the aid of other instruments is realized with only a 5 μL droplet, which has good selectivity and a low detection limit (17 nM). Importantly, this visual method provides a promising POCT tool for user-friendly molecular diagnostics. 相似文献
57.
探讨了采用Hazelett生产线,从原料到合格铝液各道工序的操作要求;特别是采用电解铝液,对每道工序操作时间和铝液质量控制提出严格要求。通过实际生产,对现有熔炼炉配置、设备台数、精炼设备配置作了详细阐述,对每道工序要达到的铝液净化参数提出严格要求,经过6次净化提纯,基本满足Hazelett铸机要求,并对熔炼设备配置的不足提出合理化建议。 相似文献
58.
Hao Li Pengcheng Zhang Shengquan Yu Hongyu Yang Bin Tang Fuhai Li Shuren Zhang 《Ceramics International》2019,45(9):11639-11647
Mg2(Ti1-xSnx)O4 (x?=?0–1) ceramics were prepared through conventional solid-state method. This paper focused on the dependence of microwave dielectric properties on crystal structural characteristics via crystal structure refinement, Raman spectra study and complex chemical bond theory. XRD spectrums delineated the phase information of a spinel structure, and structural characteristic of these compositions were achieved with the help of Rietveld refinements. Raman spectrums were used to depict the correlations between vibrational phonon modes and dielectric properties. The variation of permittivity is ascribed to the Mg2(Ti1-xSnx)O4 average bond covalency. The relationship among the B-site octahedral bond energy, tetrahedral bond energy and temperature coefficient are discussed by defining on the change rate of bond energy and the contribution rate of octahedral bond energy. The quality factor is affected by systematic total lattice energy, and the research of XPS patterns illustrated that oxygen vacancies can be effectively restrained in rich oxygen sintering process. Obviously, the microwave dielectric properties of Mg2(Ti1-xSnx)O4 compounds were obtained (= 12.18, ?=?170,130?GHz, ?=??53.1?ppm/°C, x?=?0.2). 相似文献
59.
Machine Intelligence Research - This paper proposes an image encryption algorithm LQBPNN (logistic quantum and back propagation neural network) based on chaotic sequences incorporating quantum... 相似文献
60.
Shuang Shao Yong Liu Chun-Shui Xu Ying-Xuan Xu Bin Wu Xiao-Shu Zeng Xian-Feng Lu Xiang-Jie Yang 《金属学报(英文版)》2015,(1):7-14
The microstructure and mechanical properties of Mg–6Zn–1Y and Mg–6Zn–3Y(wt%) alloys under different cooling rates were investigated. The results show that the second dendrite arm spacing(SDAS) of Mg–6Zn–1Y and Mg–6Zn–3Y is reduced by 32 and 30% with increasing cooling rates(Rc) from 10.2 to 23 K/s, which can be predicted using a empirical model of SDAS=68 R 0:45:45cand SDAS=73 R 0c, respectively. The compressive strength of both alloys increases with increasing the cooling rate, which is attributed to the increase of volume fraction(Vf) of secondary phases under high cooling rate. The interaction of the cooling rate and component with SDAS has been theoretically analyzed using interdependence theory. 相似文献