全文获取类型
收费全文 | 38194篇 |
免费 | 5378篇 |
国内免费 | 1412篇 |
专业分类
电工技术 | 1013篇 |
综合类 | 2282篇 |
化学工业 | 5897篇 |
金属工艺 | 4658篇 |
机械仪表 | 2008篇 |
建筑科学 | 1544篇 |
矿业工程 | 9929篇 |
能源动力 | 1341篇 |
轻工业 | 1147篇 |
水利工程 | 370篇 |
石油天然气 | 779篇 |
武器工业 | 266篇 |
无线电 | 2386篇 |
一般工业技术 | 5014篇 |
冶金工业 | 4090篇 |
原子能技术 | 332篇 |
自动化技术 | 1928篇 |
出版年
2024年 | 57篇 |
2023年 | 906篇 |
2022年 | 1075篇 |
2021年 | 1531篇 |
2020年 | 1839篇 |
2019年 | 1346篇 |
2018年 | 1130篇 |
2017年 | 1291篇 |
2016年 | 1326篇 |
2015年 | 1498篇 |
2014年 | 2420篇 |
2013年 | 2507篇 |
2012年 | 3241篇 |
2011年 | 3003篇 |
2010年 | 2153篇 |
2009年 | 2086篇 |
2008年 | 1958篇 |
2007年 | 2227篇 |
2006年 | 2060篇 |
2005年 | 1859篇 |
2004年 | 1468篇 |
2003年 | 1543篇 |
2002年 | 1111篇 |
2001年 | 969篇 |
2000年 | 895篇 |
1999年 | 656篇 |
1998年 | 569篇 |
1997年 | 436篇 |
1996年 | 390篇 |
1995年 | 316篇 |
1994年 | 276篇 |
1993年 | 202篇 |
1992年 | 151篇 |
1991年 | 115篇 |
1990年 | 94篇 |
1989年 | 88篇 |
1988年 | 45篇 |
1987年 | 27篇 |
1986年 | 21篇 |
1985年 | 23篇 |
1984年 | 19篇 |
1983年 | 21篇 |
1982年 | 11篇 |
1981年 | 4篇 |
1980年 | 3篇 |
1979年 | 2篇 |
1978年 | 2篇 |
1977年 | 4篇 |
1975年 | 4篇 |
1951年 | 5篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
91.
"三违"行为是导致煤矿生产安全事故发生的主要因素,本文在对企业及工人等各个方面开展调查的基础上,分析煤矿企业"三违"现状、产生原因,提出反"三违"的措施建议,可指导煤矿规范操作行为,有效防范事故发生。 相似文献
92.
马晓楠 ' target='_blank'> 吕振福 ' target='_blank'> 武秋杰 ' target='_blank'> 李作敏 ' target='_blank'> 丁国峰 ' target='_blank'> 《中州煤炭》2020,(11):103-106
我国铅锌矿产资源丰富,生产能力、消费量、出口量居世界前列,是我国的优势矿种。以10个铅锌矿能源资源基地为研究对象,对基地分布、矿山数量、产能结构、开发利用指标、矿业固废循环利用指标等进行了分析研究。研究表明,2018年,我国铅锌矿大型资源基地的矿业集中度和铅锌矿的综合利用率均高于全国平均水平。 相似文献
93.
干扰噪声直接影响局部放电法有效检测矿用高压电缆故障。基于局部放电法,综合采用理论计算、仿真实验、现场试验的方法,对比分析了短时傅里叶变换和傅里叶分析去噪法的原理和优缺点,提出了一种矿用高压电缆的局部放电去噪算法——小波阈值去噪法,同时,选择了合理的阈值函数和去噪流程。基于此,采用白噪声和连续周期信号作为高压电缆的干扰噪声,进行了模拟仿真实验。结果表明,小波阈值去噪法可有效抑制白噪声,其中,Db2小波性能和去噪效果最好;同时,现场试验结果显示,去噪后信噪比得到了显著增加,验证了小波阈值去噪法的合理性和可靠性。 相似文献
94.
95.
Yifei Li Akshay Singh Kate Reidy Seong Soon Jo Frances M. Ross Rafael Jaramillo 《Advanced functional materials》2020,30(36)
The synthesis of large‐area TiS2 thin films is reported at temperatures as low as 500 °C using a scalable two‐step method of metal film deposition followed by sulfurization in an H2S gas furnace. It is demonstrated that the lowest‐achievable sulfurization temperature depends strongly on the oxygen background during sulfurization. This dependence arises because Ti? O bonds present a substantial kinetic and thermodynamic barrier to TiS2 formation. Lowering the sulfurization temperature is important to make smooth films, and to enable integration of TiS2 and related transition metal dichalcogenides—including metastable phases and alloys—into device technology. 相似文献
96.
Jiale Feng Lupeng Yang Alexander S. Romanov Jirawit Ratanapreechachai Antti‐Pekka M. Reponen Saul T. E. Jones Mikko Linnolahti Timothy J. H. Hele Anna Khler Heinz Bssler Manfred Bochmann Dan Credgington 《Advanced functional materials》2020,30(9)
Carbene‐metal‐amides (CMAs) are a promising family of donor–bridge–acceptor molecular charge‐transfer (CT) emitters for organic light‐emitting diodes. A universal approach is demonstrated to tune the energy of their CT emission. A blueshift of up to 210 meV is achievable in solid state via dilution in a polar host matrix. The origin of this shift has two components: constraint of thermally‐activated triplet diffusion, and electrostatic interactions between guest and polar host. This allows the emission of mid‐green CMA archetypes to be tuned to sky blue without chemical modifications. Monte‐Carlo simulations based on a Marcus‐type transfer integral successfully reproduce the concentration‐ and temperature‐dependent triplet diffusion process, revealing a substantial shift in the ensemble density of states in polar hosts. In gold‐bridged CMAs, this shift does not lead to a significant change in luminescence lifetime, thermal activation energy, reorganization energy, or intersystem crossing rate. These discoveries offer new insight into coupling between the singlet and triplet manifolds in CMA materials, revealing a dominant interaction between states of CT character. The same approach is employed using materials which have been chemically modified to alter the energy of their CT state directly, shifting the emission of sky‐blue chromophores into the practical blue range. 相似文献
97.
98.
《Ceramics International》2021,47(23):33280-33285
This study investigated carbon nanotube filtration technology using catalyst particles supported on silicalite-1–biomorphic carbon materials (BCMs). Aqueous solutions of Mn(II), Cu(II), Cr(III), Cd(II), and Pb(II) were used to test the efficiency of heavy metal ions removal. Carbon nanotubes (CNTs) were synthesized and grown on BCMs by the chemical vapor deposition method catalyzed with the catalyst (Co, Fe, and Ni). The synthesized CNTs with Co– and Fe– nanoparticles were typically multi-walled carbon nanotubes, and they showed good crystallinity (ID/IG = 1.05) and yield of (11.10 and 8.86) %. The removal efficiency of Mn(II), Cu(II), Cr(III), Cd(II), and Pb(II) ions using Co-catalyzed CNT filter was 97.57%, 98.01%, 97.89%, 97.42%, and 99.99%, respectively. 相似文献
99.
Wonjun Choi Sungjae Hong Yeonsu Jeong Yongjae Cho Hyung Gon Shin Ji Hoon Park Yeonjin Yi Seongil Im 《Advanced functional materials》2021,31(9):2009436
Among many of 2D semiconductor-based devices, type III PN junction diodes are given special attentions due to their unique function, negative differential resistance (NDR). However, it has been found uneasy to achieve well-matched type III PN junctions from 2D–2D van der Waals heterojunctions. Here, the authors present other alternatives of type III heterojunctions, using 2D p-MoTe2/organic n-type dipyrazino[2,3-f:2′,3′-h]quinoxaline-2,3,6,7,10,11-hexacarbonitrile (HAT-CN) and 2D p-WSe2/n-MoOx systems. Those junction diodes appear to well-demonstrate static and dynamic NDR behavior via resonant tunneling and electron–hole recombination. Extended to an inverter circuit, p-MoTe2/n-HAT-CN diode enables multilevel inverter characteristics as monolithically integrated with p-MoTe2 channel field effect transistor. The same NDR diode shows dynamic LC oscillation behavior under a constant DC voltage, connected to an external inductor. From p-WSe2/n-MoOx oxide diode, similar NDR behavior to those of p-MoTe2/n-HAT-CN is again observed along with LC oscillations. The authors attribute these visible oscillation results to high peak-to-valley current ratios of their organic or oxide/2D heterojunction diodes. 相似文献
100.
Development of metal dichalcogenides based air and water stable opto-electronic devices is a bottleneck in their commercial implementation. Here we address this issue by the direct catalyst-free deposition of fluorographene (FG) protective layer over monolayer MoS2 (MS), where such an atomic interface is found to be providing enormous photoresponse and chemical stability to the device. Electric field modulated (ionic liquid (IL) electrolyte based top-gated) photodetectors are developed with MS only and FG-MS heterostructure, where the MS photodetector has the responsivity of ~1.3 A/W (with VGS = 0 V while unstable with IL gating) while that of FG-MS is ~2000 A/W (with VGS = 0 V and ~8000 A/W with VGS = 1.5 V, and the detectivity ~1013). This giant photoresponse of the FG-MS is validated with the help of ultrafast transient absorption spectroscopy assisted charge carrier dynamics studies at different temperatures. The broad optical response (350–850 nm) of the FG-MS is found to be intact not only in IL based gating but also after exposing in water for a month or heat treated in air at 200 °C. Interfacing and capping with FG, developed via the direct growth method, are found to be ideal for realizing high shelf-life and good responsivity photodetectors and solar cells of several other monolayer TMDs too, while available for wafer-scale manufacture. 相似文献