全文获取类型
收费全文 | 147395篇 |
免费 | 14771篇 |
国内免费 | 7967篇 |
专业分类
电工技术 | 10131篇 |
技术理论 | 7篇 |
综合类 | 10969篇 |
化学工业 | 22955篇 |
金属工艺 | 8786篇 |
机械仪表 | 9658篇 |
建筑科学 | 11705篇 |
矿业工程 | 4632篇 |
能源动力 | 4036篇 |
轻工业 | 11111篇 |
水利工程 | 3261篇 |
石油天然气 | 7459篇 |
武器工业 | 1312篇 |
无线电 | 17166篇 |
一般工业技术 | 16462篇 |
冶金工业 | 6491篇 |
原子能技术 | 1904篇 |
自动化技术 | 22088篇 |
出版年
2024年 | 727篇 |
2023年 | 2341篇 |
2022年 | 4675篇 |
2021年 | 6267篇 |
2020年 | 4816篇 |
2019年 | 4025篇 |
2018年 | 4317篇 |
2017年 | 4941篇 |
2016年 | 4496篇 |
2015年 | 6512篇 |
2014年 | 7901篇 |
2013年 | 9527篇 |
2012年 | 10509篇 |
2011年 | 11214篇 |
2010年 | 10222篇 |
2009年 | 9916篇 |
2008年 | 9482篇 |
2007年 | 9077篇 |
2006年 | 8591篇 |
2005年 | 7156篇 |
2004年 | 4901篇 |
2003年 | 4209篇 |
2002年 | 4064篇 |
2001年 | 3451篇 |
2000年 | 2922篇 |
1999年 | 2858篇 |
1998年 | 2020篇 |
1997年 | 1657篇 |
1996年 | 1491篇 |
1995年 | 1212篇 |
1994年 | 997篇 |
1993年 | 741篇 |
1992年 | 601篇 |
1991年 | 444篇 |
1990年 | 385篇 |
1989年 | 286篇 |
1988年 | 263篇 |
1987年 | 160篇 |
1986年 | 143篇 |
1985年 | 87篇 |
1984年 | 93篇 |
1983年 | 48篇 |
1982年 | 56篇 |
1981年 | 33篇 |
1980年 | 60篇 |
1979年 | 39篇 |
1978年 | 29篇 |
1976年 | 19篇 |
1974年 | 19篇 |
1951年 | 19篇 |
排序方式: 共有10000条查询结果,搜索用时 6 毫秒
1.
Feng Wenran Li Zhen Chen Yingying Chen Jinyang Lang Haoze Wan Jianghong Gao Yan Dong Haitao 《Journal of Materials Science》2022,57(3):1881-1889
Journal of Materials Science - Although chalcogenide materials continue to generate considerable interest due to great potentials for various optoelectronic devices, annealing for a long time in... 相似文献
2.
本文将完全互补码(Complete Complementary Code, CCC)应用于多输入多输出(Multiple Input Multiple Output, MIMO)雷达目标探测中,针对具有非零多普勒的多目标检测问题,提出一种基于广义普洛黑-修-莫尔斯(Generalized Prouhet-Thue-Morse, GPTM)序列和二项式系数加权的信号处理方法。该方法分别在发射端和接收端进行处理,在发射端采用GPTM序列设计方法调整脉冲的发射顺序,以降低由多普勒引起的距离旁瓣;在接收端通过二项式设计(Binomial Design, BD)方法为各接收脉冲加上不同权重,扩大目标多普勒附近的清洁区。为综合上述两次处理的优势,将两次处理得到的距离多普勒谱进行逐点最小化处理,得到最终的距离多普勒谱,然后进行有序恒虚警检测。仿真结果表明,本文所提的信号处理方法具有良好的旁瓣抑制效果和多普勒分辨率,能够有效检测出非零多普勒目标。 相似文献
4.
Yarn-dyed fabric is often woven from warp and weft yarns in the same color depth to ensure a uniform color appearance. The difference in color depth between warp and weft tends to result in the uneven color of the yarn-dyed fabric. This article aims to establish a color tolerance for yarn-dyed fabric that can be woven with a qualified color appearance but from the warp and weft yarns in different color depths. A total of 27 yarn-dyed fabric samples in three color series (red, yellow, and blue) were evaluated by using the yarn-dyed fabric from warp and weft yarns in the same color depth of 2% (on weight of fabric, owf) as the standard. Visual assessment and instrumental measurement of color were carried out to establish the color tolerance ellipse that was defined as CMC (Color Measurement Committee) color differences (2:1) of no more than 1.00. It was found that the color strengths (K/S) and color differences (ΔECMC(2:1)) of these fabric samples for each color series had linear relationships with the color depths of warp and weft yarns. The color tolerance ellipses indicated that, even though the warp and weft yarns had an apparent color difference, they could be woven in fabrics with relatively uniform color appearance and meet the requirements for yarn-dyed fabric. This work provided valuable insight into the production of qualified yarn-dyed fabrics from unqualified dyed yarns. 相似文献
5.
Photoresponsive biomaterials are experiencing a transition from in vitro models to in vivo demonstrations that point toward clinical translation. Dynamic hydrogels for cell encapsulation, light-responsive carriers for controlled drug delivery, and nanomaterials containing photosensitizers for photodynamic therapy are relevant examples. Nonetheless, the step to the clinic largely depends on their combination with technologies to bring light into the body. This review highlights the challenge of photoactivation in vivo, and presents strategies for light management that can be adopted for this purpose. The authors’ focus is on technologies that are materials-driven, particularly upconversion nanoparticles that assist in “direct path” light delivery through tissue, and optical waveguides that “clear the path” between external light source and in vivo target. The authors’ intention is to assist the photoresponsive biomaterials community transition toward medical technologies by presenting light delivery concepts that can be integrated with the photoresponsive targets. The authors also aim to stimulate further innovation in materials-based light delivery platforms by highlighting needs and opportunities for in vivo photoactivation of biomaterials. 相似文献
6.
为了适应煤矿产能的提升和开采规模的不断加大,南岭矿对现有机电运输设备进行了重新的选型和升级.实际应用表明,优化后的井下运输设备的运输能力能够很好地满足矿井的安全高效生产. 相似文献
7.
Tao Feng Mingde Tong Shuotian Yao Hejun Li Shifeng Wen Hongjiao Lin 《Journal of the European Ceramic Society》2021,41(1):158-166
Composites based on hafnium carbide and reinforced with continuous naked carbon fiber with and without PyC interface were prepared at low temperature by precursor infiltration and pyrolysis and chemical vapor deposition method. The microstructure, mechanical property, cyclic ablation and fiber bundle push-in tests of the composites were investigated. The results show that after three times ablation cycles, the bending strength of samples without PyC interface decreased by 63.6 %; the bending strength of samples with PyC interface only decreased by 37.8 %. The force displacement curve of the samples with PyC interface presented a well pseudoplastic deformation state. The mechanical behavior difference of two kinds of composites was due to crucial function of PyC interface phase including protection of fiber and weakening of fiber/matrix interface. 相似文献
8.
Shilin Du Yichen Dong Feiqiang Guo Beile Tian Songbo Mao Lin Qian Chengyun Xin 《International Journal of Hydrogen Energy》2021,46(27):14138-14147
The potential of using high metals containing coal gangue and lignite to prepare high-activity coal char-based catalysts is investigated for effective biomass tar decomposition. Loose structure and rough surface are formed for these char-based catalysts with heterogeneous distribution of a large number of inorganic particles. In the biomass tar decomposition, the performance of the coal char-based catalysts is significantly influenced by the content of the metals in the raw materials and coal gangue char (GC) with the ash content as high as 50.80% exhibits the highest activity in this work. A high biomass tar conversion efficiency of 93.5% is achieved at 800 °C along with a significant increase in the fuel gas product. During the five-time consecutive tests, the catalytic performance of GC increases a little at the second or third times reuse and remains relatively stable, showing the remarkable stability of the catalyst in biomass tar decomposition applications. 相似文献
9.
Fenqi Du Dongmei Yang Yue Sun Yang Jiao Feng Teng Haibo Fan 《Ceramics International》2021,47(4):4963-4971
Ultrawide band gap semiconductor materials have attracted considerable attention in recent years owing to their great potential in the photocatalytic field. In this study, Zn-doped Ga2O3 nanofibers with various concentrations were synthesized via electrospinning; they exhibited a superior photocatalytic degradation performance of rhodamine B dye compared to that of undoped Ga2O3 nanofibers. The Zn dopant replaced Ga sites via replacement doping, which could increase the concentration of oxygen vacancies and lead to enhanced photocatalytic properties. When the Zn concentration increased, a Ga2O3/ZnGa2O4 hybrid structure formed, which could further enhance the photocatalytic performance. The separation of photogenerated carriers due to Zn doping and heterojunctions were the primary causes of the enhanced photocatalytic performance. This study provides experimental data for the fabrication of high-performance photocatalysts based on Ga2O3 nanomaterials. 相似文献
10.