全文获取类型
收费全文 | 8676篇 |
免费 | 1104篇 |
国内免费 | 801篇 |
专业分类
电工技术 | 845篇 |
综合类 | 610篇 |
化学工业 | 1353篇 |
金属工艺 | 311篇 |
机械仪表 | 265篇 |
建筑科学 | 287篇 |
矿业工程 | 560篇 |
能源动力 | 329篇 |
轻工业 | 201篇 |
水利工程 | 49篇 |
石油天然气 | 327篇 |
武器工业 | 1231篇 |
无线电 | 1735篇 |
一般工业技术 | 1752篇 |
冶金工业 | 183篇 |
原子能技术 | 54篇 |
自动化技术 | 489篇 |
出版年
2024年 | 17篇 |
2023年 | 140篇 |
2022年 | 314篇 |
2021年 | 301篇 |
2020年 | 307篇 |
2019年 | 240篇 |
2018年 | 221篇 |
2017年 | 358篇 |
2016年 | 366篇 |
2015年 | 336篇 |
2014年 | 572篇 |
2013年 | 519篇 |
2012年 | 609篇 |
2011年 | 664篇 |
2010年 | 572篇 |
2009年 | 495篇 |
2008年 | 476篇 |
2007年 | 550篇 |
2006年 | 538篇 |
2005年 | 461篇 |
2004年 | 371篇 |
2003年 | 387篇 |
2002年 | 313篇 |
2001年 | 264篇 |
2000年 | 219篇 |
1999年 | 167篇 |
1998年 | 151篇 |
1997年 | 128篇 |
1996年 | 101篇 |
1995年 | 94篇 |
1994年 | 88篇 |
1993年 | 79篇 |
1992年 | 51篇 |
1991年 | 27篇 |
1990年 | 24篇 |
1989年 | 16篇 |
1988年 | 6篇 |
1987年 | 12篇 |
1986年 | 4篇 |
1983年 | 4篇 |
1982年 | 2篇 |
1981年 | 3篇 |
1979年 | 1篇 |
1978年 | 2篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1974年 | 1篇 |
1958年 | 1篇 |
1951年 | 3篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Eitan Oksenberg Calvin Fai Ivan G. Scheblykin Ernesto Joselevich Eva L. Unger Thomas Unold Charles Hages Aboma Merdasa 《Advanced functional materials》2021,31(22):2010704
Understanding energy transport in metal halide perovskites is essential to effectively guide further optimization of materials and device designs. However, difficulties to disentangle charge carrier diffusion, photon recycling, and photon transport have led to contradicting reports and uncertainty regarding which mechanism dominates. In this study, monocrystalline CsPbBr3 nanowires serve as 1D model systems to help unravel the respective contribution of energy transport processes in metal-halide perovskites. Spatially, temporally, and spectrally resolved photoluminescence (PL) microscopy reveals characteristic signatures of each transport mechanism from which a robust model describing the PL signal accounting for carrier diffusion, photon propagation, and photon recycling is developed. For the investigated CsPbBr3 nanowires, an ambipolar carrier mobility of μ = 35 cm2 V−1 s−1 is determined, and is found that charge carrier diffusion dominates the energy transport process over photon recycling. Moreover, the general applicability of the developed model is demonstrated on different perovskite compounds by applying it to data provided in previous related reports, from which clarity is gained as to why conflicting reports exist. These findings, therefore, serve as a useful tool to assist future studies aimed at characterizing energy transport mechanisms in semiconductor nanowires using PL. 相似文献
2.
3.
《International Journal of Hydrogen Energy》2022,47(13):8372-8381
The hydrogen production capabilities of the membrane reactor combining V-10 mol%Fe hydrogen permeable alloy membrane with Ru/Cs2O/Pr6O11 ammonia decomposition catalyst are studied. The ammonia conversion is improved by 1.7 times compared to the Ru/Cs2O/Pr6O11 catalyst alone by removing the produced hydrogen through the V-10mol%Fe alloy membrane during the ammonia decomposition. 79% of the hydrogen atoms contained in the ammonia gas are extracted directly as high-purity hydrogen gas. Both the Ru/Cs2O/Pr6O11 catalyst and the V-10 mol% Fe alloy membrane are highly durable, and the initial performance of the hydrogen separation rate lasts for more than 3000 h. The produced hydrogen gas conforms to ISO 14687–2:2019 Grade D for fuel cell vehicles because the ammonia and nitrogen concentrations are less than 0.1 ppm and 100 ppm, respectively. 相似文献
4.
5.
A. Nakano T. Shimazaki M. Sekiya H. Shiozawa K. Ohtsuka A. Aoyagi T. Iwakiri Z. Mikami M. Sato Y. Sugino K. Kinoshita T. Matsuoka T. Imamura Y. Takayama K. Yamamoto 《International Journal of Hydrogen Energy》2021,46(29):15649-15659
Monitoring the temperature in liquid hydrogen (LH2) storage tanks on ships is important for the safety of maritime navigation. In addition, accurate temperature measurement is also required for commercial transactions. Temperature and pressure define the density of liquid hydrogen, which is directly linked to trading interests. In this study, we developed and tested a liquid hydrogen temperature monitoring system that uses platinum resistance sensors with a nominal electrical resistance of approximately 1000 Ω at room temperature, PT-1000, for marine applications. The temperature measurements were carried out using a newly developed temperature monitoring system under different pressure conditions. The measured values are compared with a calibrated reference PT-1000 resistance thermometer. We confirm a measurement accuracy of ±50 mK in a pressure range of 0.1 MPa–0.5 MPa. 相似文献
6.
《International Journal of Hydrogen Energy》2021,46(58):29858-29888
Doped semiconductor, a newly discovered plasmonic nanomaterial, has attracted tremendous interest due to its tunable properties. In the field of photocatalysis, the perfect combination of metal-like and semiconductor properties makes it the replacement and supplement of metal plasmonic nanomaterials. This new plasmonic photocatalysis offers high conversion efficiencies and wide optical absorption range with low fabrication costs. This article reviews the recent developments and achievements by which the localized surface plasmon resonance (LSPR) in non-metal plasmonic nanomaterial for photocatalytic applications, including pure non-metal plasmonic photocatalysts and various enhancement strategies such as doping, co-catalyst, heterojunction, LSPR coupling and upconversion luminescence enhancement. It broadens the horizons for plasmonics in the study of photocatalysis and even in energy-related applications. 相似文献
7.
采用多级离子交换法对加氢精制催化剂载体进行脱钠处理,考察了铵盐种类、浸泡时间、交换温度和铵盐浓度对脱钠效果的影响。以浸泡时间、交换温度和铵盐浓度3个主要影响因素做Box-Behnken实验设计,钠含量为响应函数,建立相应数学模型。实验结果表明,脱钠效果较优的铵盐为乙酸铵。最佳工艺条件:浸泡时间为60 min、交换温度为60 ℃、铵盐质量分数为5.5%。Box-Behnken实验设计法用于加氢精制催化剂载体脱钠工艺优化是可行的,数学模型的预测值与实验观察值相符。 相似文献
8.
为获得持久抗菌的功能丝绸材料,采用硝酸、磷酸、亚硝酸钠体系将原料壳聚糖的C6位伯羟基选择性氧化为羧基制得水溶性氧化壳聚糖(OCS),使OCS的羧基与脱胶蚕丝织物(SFF)的氨基反应,得到氧化壳聚糖改性蚕丝织物(OCSMSF)。借助核磁共振仪、扫描电子显微镜、红外光谱仪、X射线衍射仪等手段表征了OCS与OCSMSF的化学结构,测试了OCSMSF的力学、吸湿、抗菌等性能。结果表明:酰胺反应已将氧化壳聚糖分子化学键合在SFF中,OCS改性蚕丝纤维的结晶度降低;在优化反应参数条件下,OCS接枝蚕丝织物的质量增加率达到9.17%,OCSMSF的强力略有减小,而吸湿性提高42.92%,OCSMSF对测试细菌的抑菌率大于94%,且抗菌耐洗涤性好,同时OCSMSF对仙人掌黄酮提取物有良好的缓释效果。 相似文献
9.
为提升采用钢带凉药工艺的乳化炸药生产线的敏化效果,在钢带上方安置了液体喷洒装置,改化学敏化剂和促进剂滴入添加工艺为喷洒添加工艺。研究表明:该工艺分别通过并联2~4个外切式二流体喷嘴,在0.01~0.05 MPa低压空气剪切下,可将含有化学敏化剂、促进剂的溶液均匀喷洒至乳化基质上,能够较快、均匀分散,提升了敏化效果,减轻了乳化基质的破坏程度,改善了产品的综合性能。 相似文献
10.