全文获取类型
收费全文 | 90881篇 |
免费 | 10317篇 |
国内免费 | 6114篇 |
专业分类
电工技术 | 7507篇 |
技术理论 | 5篇 |
综合类 | 7730篇 |
化学工业 | 13215篇 |
金属工艺 | 5174篇 |
机械仪表 | 6129篇 |
建筑科学 | 7109篇 |
矿业工程 | 3259篇 |
能源动力 | 2767篇 |
轻工业 | 7160篇 |
水利工程 | 2216篇 |
石油天然气 | 4185篇 |
武器工业 | 1063篇 |
无线电 | 11276篇 |
一般工业技术 | 9617篇 |
冶金工业 | 3773篇 |
原子能技术 | 1287篇 |
自动化技术 | 13840篇 |
出版年
2024年 | 479篇 |
2023年 | 1539篇 |
2022年 | 3050篇 |
2021年 | 4317篇 |
2020年 | 3150篇 |
2019年 | 2593篇 |
2018年 | 2816篇 |
2017年 | 3177篇 |
2016年 | 2944篇 |
2015年 | 4223篇 |
2014年 | 5220篇 |
2013年 | 6231篇 |
2012年 | 7088篇 |
2011年 | 7150篇 |
2010年 | 6614篇 |
2009年 | 6182篇 |
2008年 | 5925篇 |
2007年 | 5589篇 |
2006年 | 5211篇 |
2005年 | 4231篇 |
2004年 | 3089篇 |
2003年 | 2800篇 |
2002年 | 3247篇 |
2001年 | 2724篇 |
2000年 | 1816篇 |
1999年 | 1369篇 |
1998年 | 875篇 |
1997年 | 704篇 |
1996年 | 601篇 |
1995年 | 547篇 |
1994年 | 405篇 |
1993年 | 254篇 |
1992年 | 245篇 |
1991年 | 195篇 |
1990年 | 137篇 |
1989年 | 111篇 |
1988年 | 83篇 |
1987年 | 47篇 |
1986年 | 46篇 |
1985年 | 32篇 |
1984年 | 26篇 |
1983年 | 12篇 |
1982年 | 24篇 |
1981年 | 18篇 |
1980年 | 38篇 |
1979年 | 21篇 |
1978年 | 12篇 |
1977年 | 15篇 |
1976年 | 22篇 |
1959年 | 14篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
12.
现阶段的语义解析方法大部分都基于组合语义,这类方法的核心就是词典。词典是词汇的集合,词汇定义了自然语言句子中词语到知识库本体中谓词的映射。语义解析一直面临着词典中词汇覆盖度不够的问题。针对此问题,该文在现有工作的基础上,提出了基于桥连接的词典学习方法,该方法能够在训练中自动引入新的词汇并加以学习,为了进一步提高新学习到的词汇的准确度,该文设计了新的词语—二元谓词的特征模板,并使用基于投票机制的核心词典获取方法。该文在两个公开数据集(WebQuestions和Free917)上进行了对比实验,实验结果表明,该文方法能够学习到新的词汇,提高词汇的覆盖度,进而提升语义解析系统的性能,特别是召回率。 相似文献
13.
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
14.
15.
Wang Hay Kan Chenxi Wei Dongchang Chen Tao Bo Bao‐Tian Wang Yan Zhang Yangchao Tian Jun‐Sik Lee Yijin Liu Guoying Chen 《Advanced functional materials》2019,29(17)
Lithium‐rich disordered rock‐salt oxides have attracted great interest owing to their promising performance as Li‐ion battery cathodes. While experimental and theoretical efforts are critical in advancing this class of materials, a fundamental understanding of key property changes upon Li extraction is largely missing. In the present study, single‐crystal synthesis of a new disordered rock‐salt cathode material, Li1.3Ta0.3Mn0.4O2 (LTMO), and its use as a model compound to investigate Li concentration–driven evolution of local cationic ordering, charge compensation, and chemical distribution are reported. Through the combined use of 2D and 3D X‐ray nanotomography, it is shown that Li removal accompanied by oxygen oxidation is correlated with the development of morphological defects such as particle cracking. Chemical heterogeneity, quantified by subparticle level distribution of Mn valence state, is minimal during Mn redox, which drastically increases upon the formation of cracks during oxygen redox. Density functional theory and bond valence sum mismatch calculations reveal the presence of local short‐range ordering in the pristine oxide, which gradually disappears along with the extraction of Li. The study suggests that with cycling the transformation into true cation–disordered state can be expected, which likely impacts the voltage profile and obtainable energy density of the oxide cathodes. 相似文献
16.
This paper is concerned with the problem of joint input and state estimation for linear stochastic systems with direct feedthrough. Based on the fact that each unknown input between any two time steps is always bounded, a novel improved algorithm is proposed. Compared with existing results, this algorithm can effectively enhance estimation accuracy. Moreover, the stability of the algorithm is also discussed. Finally, an illustrative example is given to demonstrate the effectiveness of the proposed approach. 相似文献
17.
煤电平均供电煤耗作为评价能源系统效率的指标已在行业内广泛应用。但该项指标无法很好地反映一个国家、地区的用电结构与用电能耗水平。为此,参照行业内普遍采用的火电厂发电煤耗和供电煤耗指标,定义“综合用电煤耗”,即用户每用1 kW?h电“消耗”的标准煤量(单位:g/(kW?h))。在此基础上,提出“综合发电煤耗”与“综合供电煤耗”的概念,形成完整的指标评价体系。对近年典型省份指标值的研究表明,该指标体系能够很好地反映供给侧国家、省区或企业的发电结构与电能生产能耗水平。这一指标体系能够为正确理解和计算用电、输电与电能替代项目的化石能源消耗量及其排放量提供依据。 相似文献
18.
19.
Correlation between instrumental texture and colour quality attributes with sensory analysis of selected cheeses as affected by fat contents
下载免费PDF全文
![点击此处可从《International Journal of Food Science & Technology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
A. Półtorak J. Wyrwisz M. Moczkowska M. Marcinkowska‐Lesiak A. Stelmasiak U. Ulanicka M. Zalewska A. Wierzbicka Da‐Wen Sun 《International Journal of Food Science & Technology》2015,50(4):999-1008
This study evaluated several physical and sensory parameters of different types of cheese available in the Polish market. The measurements of textural properties were conducted in an Instron universal testing machine, while the colour properties of cheeses were measured using a Minolta chromameter. The chemical composition was determined by means of the near‐infrared spectroscopy (NIRs). Moreover, a trained sensory panel was invited to assess the cheese texture‐related properties. Generally, cheeses with reduced fat content were characterised by higher hardness, adhesiveness, cohesiveness and elasticity. Texture‐related parameters of cheese with canola oil were comparable to that of most of full‐fat cheeses. The correlation analysis between physical and sensory attributes related to cheese textural properties indicated the potential applications of TPA, shear and penetration tests (r = 0.766, r = 0.75 and r = 0.765, respectively) for the evaluation of sensory properties related to the hardness. Meanwhile, the elasticity of cheese obtained from sensory evaluation was strongly correlated with the elasticity determined from the shear test (r = 0.722) and moderately correlated with the elasticity from penetration test (r = 0.588), indicating a need to refine the method of penetration test. In addition, cheeses exhibited higher meltability during convection heating at 230 °C than microwave heating. The values of meltability for cheese with reduced fat content were lower than those of full‐fat cheese. 相似文献
20.
主要阐述在距离台技术大楼2 km远的海盐一家门频道采、编、播系统的构建。整个系统的搭建,充分考虑了时间、空间、距离等各方面的要求,突出异地构建的特点,融合了电视台的节目录制、安全播出、计算机网络、远程控制等多方面技术。 相似文献