全文获取类型
收费全文 | 133301篇 |
免费 | 10643篇 |
国内免费 | 5928篇 |
专业分类
电工技术 | 7492篇 |
技术理论 | 13篇 |
综合类 | 9730篇 |
化学工业 | 22043篇 |
金属工艺 | 7791篇 |
机械仪表 | 8718篇 |
建筑科学 | 11005篇 |
矿业工程 | 3771篇 |
能源动力 | 3789篇 |
轻工业 | 9247篇 |
水利工程 | 2540篇 |
石油天然气 | 7252篇 |
武器工业 | 1218篇 |
无线电 | 14685篇 |
一般工业技术 | 15504篇 |
冶金工业 | 6097篇 |
原子能技术 | 1445篇 |
自动化技术 | 17532篇 |
出版年
2024年 | 187篇 |
2023年 | 1655篇 |
2022年 | 2766篇 |
2021年 | 4363篇 |
2020年 | 3464篇 |
2019年 | 3043篇 |
2018年 | 3350篇 |
2017年 | 3772篇 |
2016年 | 3489篇 |
2015年 | 5021篇 |
2014年 | 6235篇 |
2013年 | 7569篇 |
2012年 | 8631篇 |
2011年 | 9260篇 |
2010年 | 8483篇 |
2009年 | 8280篇 |
2008年 | 8003篇 |
2007年 | 7894篇 |
2006年 | 8160篇 |
2005年 | 6900篇 |
2004年 | 4969篇 |
2003年 | 4376篇 |
2002年 | 4561篇 |
2001年 | 4064篇 |
2000年 | 3295篇 |
1999年 | 3408篇 |
1998年 | 2757篇 |
1997年 | 2261篇 |
1996年 | 2107篇 |
1995年 | 1671篇 |
1994年 | 1483篇 |
1993年 | 1081篇 |
1992年 | 818篇 |
1991年 | 642篇 |
1990年 | 465篇 |
1989年 | 395篇 |
1988年 | 334篇 |
1987年 | 188篇 |
1986年 | 126篇 |
1985年 | 105篇 |
1984年 | 49篇 |
1983年 | 48篇 |
1982年 | 54篇 |
1981年 | 32篇 |
1980年 | 32篇 |
1979年 | 11篇 |
1976年 | 3篇 |
1959年 | 3篇 |
1958年 | 2篇 |
1951年 | 4篇 |
排序方式: 共有10000条查询结果,搜索用时 234 毫秒
31.
Bin Feng Xin Jiang Guisheng Zou Wengan Wang Tianming Sun Heng Yang Guanlei Zhao Mingye Dong Yu Xiao Hongwei Zhu Lei Liu 《Advanced functional materials》2021,31(29):2102359
The realization of liquid metal-based wearable systems will be a milestone toward high-performance, integrated electronic skin. However, despite the revolutionary progress achieved in many other components of electronic skin, liquid metal-based flexible sensors still suffer from poor sensitivity due to the insufficient resistance change of liquid metal to deformation. Herein, a nacre-inspired architecture composed of a biphasic pattern (liquid metal with Cr/Cu underlayer) as “bricks” and strain-sensitive Ag film as “mortar” is developed, which breaks the long-standing sensitivity bottleneck of liquid metal-based electronic skin. With 2 orders of magnitude of sensitivity amplification while maintaining wide (>85%) working range, for the first time, liquid metal-based strain sensors rival the state-of-art counterparts. This liquid metal composite features spatially regulated cracking behavior. On the one hand, hard Cr cells locally modulate the strain distribution, which avoids premature cut-through cracks and prolongs the defect propagation in the adjacent Ag film. On the other hand, the separated liquid metal cells prevent unfavorable continuous liquid-metal paths and create crack-free regions during strain. Demonstrated in diverse scenarios, the proposed design concept may spark more applications of ultrasensitive liquid metal-based electronic skins, and reveals a pathway for sensor development via crack engineering. 相似文献
32.
Nan Wu Xiaodong Li Mu Zhang Yi Ren Qi Zhu Haijun Peng Hongqiang Ru Xudong Sun 《Journal of the European Ceramic Society》2021,41(4):2898-2907
Refining ceramic microstructures to the nanometric range to minimize light scattering provides an interesting methodology for developing novel optical ceramic materials. In this work, we reported the fabrication and properties of a new nanocomposite optical ceramic of Gd2O3-MgO. The citric acid sol-gel combustion method was adopted to fabricate Gd2O3-MgO nanocomposites with fine-grain sizes, dense microstructures and homogeneous phase domains. Nanopowders with low agglomeration and improved sinterability can be obtained by elaborating Φ values. Further refining of the microstructure of the nanocomposites was achieved by elaborating the hot-pressing conditions. The sample sintered at 65 MPa and 1300 °C showed a quite high hardness value of 14.3 ± 0.2 GPa, a high transmittance of 80.3 %–84.7 % over the 3?6 μm wavelength range, due mainly to its extremely fine-grain size of Gd2O3 and MgO (93 and 78 nm, respectively) and high density. 相似文献
33.
隐患采空区是目前影响露天开采矿山安全生产的主要危害源之一。随着台阶开采的不断剥离,露天开采境界内各台阶与地下空区群的隔离层厚度越来越薄,随时有可能发生采空区顶板坍塌事故。考虑到露天矿采空区地质赋存条件和围岩稳固性等特征,以弓长岭露天铁矿浅层采空区为工程背景,运用现场监测和数值模拟相结合的手段综合分析了浅层采空区的稳定性。将液体静力水准地表沉降监测系统的监测数据与FLAC数值模拟结果对比,调整蠕变参数使得数值模拟的蠕变速率与现场监测结果一致,而后据此进行未来结果的预测。最终根据地表沉降数据确定的蠕变参数取值为A=1.0×10^-12、m=1.75、n=0.35。研究表明:静力水准测点地表最大沉降位移为-9.8 mm,蠕变计算结果顶板最大垂直位移约20.4 mm,应力最大值约25 MPa,综合分析显示该采空区较稳定。上述研究提供了一种基于采空区现场监测数据的数值模拟蠕变分析方法,可为类似矿山采空区稳定性分析提供借鉴。 相似文献
34.
CO2捕集作为温室气体排放控制的有效手段已成为重要研究课题。作为新兴捕集技术之一,低温CO2捕集因产品纯度高、无附加污染等优势受到关注。然而,该技术能耗和捕集率对于气体中CO2浓度十分敏感,对于高CO2浓度气体可获得较高的CO2捕集率和较低能耗水平。基于此,本文提出了耦合膜分离的新型CO2低温捕集系统,通过膜材料选择渗透性实现待捕集气体CO2浓度主动调控,并在最优浓度下进行CO2低温捕集。首先基于不同传统低温捕集系统特点,对比分析了不同耦合系统模式,从而确定了最优耦合系统结构。针对最优耦合系统进行了运行参数优化,并分别基于实现系统捕集能耗最低与捕集率最高的目标,获得了膜渗透侧CO2浓度与进气CO2浓度间的关系式,为该耦合系统中膜组件选型提供指导。研究表明,本文提出的耦合系统捕集能耗为1.92MJ/kgCO2,相比于传统单一低温系统捕集能耗可降低16.5%。 相似文献
36.
Chuntao Lan Haiyang Zou Longfei Wang Meng Zhang Shuang Pan Ying Ma Yiping Qiu Zhong Lin Wang Zhiqun Lin 《Advanced materials (Deerfield Beach, Fla.)》2020,32(47):2005481
Despite recent rapid advances in metal halide perovskites for use in optoelectronics, the fundamental understanding of the electrical-poling-induced ion migration, accounting for many unusual attributes and thus performance in perovskite-based devices, remain comparatively elusive. Herein, the electrical-poling-promoted polarization potential is reported for rendering hybrid organic–inorganic perovskite photodetectors with high photocurrent and fast response time, displaying a tenfold enhancement in the photocurrent and a twofold decrease in the response time after an external electric field poling. First, a robust meniscus-assisted solution-printing strategy is employed to facilitate the oriented perovskite crystals over a large area. Subsequently, the electrical poling invokes the ion migration within perovskite crystals, thus inducing a polarization potential, as substantiated by the surface potential change assessed by Kelvin probe force microscopy. Such electrical-poling-induced polarization potential is responsible for the markedly enhanced photocurrent and largely shortened response time. This work presents new insights into the electrical-poling-triggered ion migration and, in turn, polarization potential as well as into the implication of the latter for optoelectronic devices with greater performance. As such, the utilization of ion-migration-produced polarization potential may represent an important endeavor toward a wide range of high-performance perovskite-based photodetectors, solar cells, transistors, scintillators, etc. 相似文献
37.
Yan Jing Zhu Rongying Wu Fan Zhao Ziyin Ye Huan Hou Mengying Liu Yong Yin Lichen 《Nano Research》2020,13(10):2706-2715
Nano Research - Insufficient intratumoral penetration greatly hurdles the anticancer performance of nanomedicine. To realize highly efficient tumor penetration in a precisely and spatiotemporally... 相似文献
38.
39.
40.