全文获取类型
收费全文 | 95553篇 |
免费 | 10664篇 |
国内免费 | 7122篇 |
专业分类
电工技术 | 8358篇 |
技术理论 | 4篇 |
综合类 | 8852篇 |
化学工业 | 11830篇 |
金属工艺 | 6582篇 |
机械仪表 | 7102篇 |
建筑科学 | 7555篇 |
矿业工程 | 3376篇 |
能源动力 | 2651篇 |
轻工业 | 8627篇 |
水利工程 | 3285篇 |
石油天然气 | 4230篇 |
武器工业 | 1331篇 |
无线电 | 10868篇 |
一般工业技术 | 8872篇 |
冶金工业 | 3843篇 |
原子能技术 | 1561篇 |
自动化技术 | 14412篇 |
出版年
2024年 | 539篇 |
2023年 | 1505篇 |
2022年 | 3388篇 |
2021年 | 4437篇 |
2020年 | 3330篇 |
2019年 | 2451篇 |
2018年 | 2765篇 |
2017年 | 3262篇 |
2016年 | 2822篇 |
2015年 | 4511篇 |
2014年 | 5590篇 |
2013年 | 6506篇 |
2012年 | 7818篇 |
2011年 | 8290篇 |
2010年 | 7723篇 |
2009年 | 7227篇 |
2008年 | 7508篇 |
2007年 | 7282篇 |
2006年 | 6161篇 |
2005年 | 4995篇 |
2004年 | 3573篇 |
2003年 | 2381篇 |
2002年 | 2298篇 |
2001年 | 2066篇 |
2000年 | 1655篇 |
1999年 | 919篇 |
1998年 | 505篇 |
1997年 | 361篇 |
1996年 | 305篇 |
1995年 | 281篇 |
1994年 | 213篇 |
1993年 | 148篇 |
1992年 | 127篇 |
1991年 | 78篇 |
1990年 | 62篇 |
1989年 | 52篇 |
1988年 | 33篇 |
1987年 | 27篇 |
1986年 | 20篇 |
1985年 | 14篇 |
1984年 | 8篇 |
1983年 | 6篇 |
1982年 | 8篇 |
1981年 | 19篇 |
1980年 | 29篇 |
1979年 | 17篇 |
1976年 | 1篇 |
1974年 | 1篇 |
1959年 | 12篇 |
1951年 | 9篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
Bin Zhang Meng Zhang Yu Li Huansheng Cheng Jianming Zheng 《Ceramics International》2019,45(3):3081-3087
Proton induced X-ray emission (PIXE) technique and factor analysis were used to study the recovery of making-technology of Chinese Longquan celadon made in the late Southern Song Dynasty (1127–1279 CE). Based on factor analysis, for the raw material for body and the recipe for glaze, there is a close but slightly different relationship between these Longquan celadons unearthed from the core area of Dayao and the non-core area, despite all the Longquan celadons belong to the high-calcium-glaze system. The chemical compositions of most of the tentative body and glaze samples are very close to those of Longquan celadons unearthed from the core area of Dayao and the non-core area. This study can provide a guidance for recovery of making-technology of Longquan celandon. 相似文献
32.
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
33.
34.
35.
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
36.
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
37.
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
38.
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
39.
针对基于规则和统计的传统中文简历解析方法效率低、成本高、泛化能力差的缺点,提出一种基于特征融合的中文简历解析方法,即级联Word2Vec生成的词向量和用BLSTM(Bidirectional Long Short-Term Memory)建模字序列生成的词向量,然后再结合BLSTM和CRF(Conditional Random Fields)对中文简历进行解析(BLSTM-CRF)。为了提高中文简历解析的效率,级联包含字序列信息的词向量和用Word2Vec生成的词向量,融合成一个新的词向量表示;再由BLSTM强大的学习能力融合词的上下文信息,输出所有可能标签序列的分值给CRF层;再由CRF引入标签之间约束关系求解最优序列。利用梯度下降算法训练神经网络,使用预先训练的词向量和Dropout优化神经网络,最终完成对中文简历的解析工作。实验结果表明,所提的特征融合方法优于传统的简历解析方法。 相似文献
40.
2A12铝合金化学铣切加工工艺探讨 总被引:1,自引:0,他引:1
为了精确加工2Al2铝合金,探讨了化铣时间和温度对其化铣速率及表面粗糙度的影响,采用现代技术对化铣工件的力学性能进行了测试与分析.结果表明:延长非化铣部位保护胶固化时间并使保护部位向非加工面位移3~5 mm可很好地解决未化铣区域的腐蚀问题;随化铣时间的延长,化铣速率降低,且化铣温度与化铣速率呈现正相关性;化铣表面的粗糙度随化铣时间的延长而增加,随化铣温度的升高呈先减小后增加的趋势;化铣后材料的抗拉强度和屈服强度均有所提高. 相似文献