全文获取类型
收费全文 | 7804篇 |
免费 | 515篇 |
国内免费 | 10篇 |
专业分类
电工技术 | 59篇 |
综合类 | 18篇 |
化学工业 | 1915篇 |
金属工艺 | 184篇 |
机械仪表 | 156篇 |
建筑科学 | 330篇 |
矿业工程 | 27篇 |
能源动力 | 233篇 |
轻工业 | 714篇 |
水利工程 | 112篇 |
石油天然气 | 21篇 |
无线电 | 463篇 |
一般工业技术 | 1690篇 |
冶金工业 | 1207篇 |
原子能技术 | 21篇 |
自动化技术 | 1179篇 |
出版年
2024年 | 12篇 |
2023年 | 64篇 |
2022年 | 139篇 |
2021年 | 208篇 |
2020年 | 168篇 |
2019年 | 201篇 |
2018年 | 220篇 |
2017年 | 208篇 |
2016年 | 244篇 |
2015年 | 187篇 |
2014年 | 315篇 |
2013年 | 565篇 |
2012年 | 468篇 |
2011年 | 674篇 |
2010年 | 453篇 |
2009年 | 423篇 |
2008年 | 475篇 |
2007年 | 438篇 |
2006年 | 366篇 |
2005年 | 326篇 |
2004年 | 267篇 |
2003年 | 251篇 |
2002年 | 229篇 |
2001年 | 114篇 |
2000年 | 102篇 |
1999年 | 101篇 |
1998年 | 91篇 |
1997年 | 91篇 |
1996年 | 76篇 |
1995年 | 84篇 |
1994年 | 81篇 |
1993年 | 56篇 |
1992年 | 67篇 |
1991年 | 27篇 |
1990年 | 31篇 |
1989年 | 42篇 |
1988年 | 42篇 |
1987年 | 40篇 |
1986年 | 35篇 |
1985年 | 54篇 |
1984年 | 45篇 |
1983年 | 41篇 |
1982年 | 40篇 |
1981年 | 25篇 |
1980年 | 28篇 |
1979年 | 20篇 |
1978年 | 21篇 |
1977年 | 18篇 |
1976年 | 17篇 |
1975年 | 11篇 |
排序方式: 共有8329条查询结果,搜索用时 15 毫秒
1.
Carolyn A. Grimley Stephen Funni Christopher Green Elizabeth C. Dickey 《Journal of the European Ceramic Society》2021,41(4):2807-2817
In flash sintering experiments, the thermal history of the sample is key to understanding the mechanisms underlying densification rate and final properties. By combining robust temperature measurements with current-ramp-rate control, this study examined the effects of the thermal profile on the flash sintering of yttria-stabilized zirconia, with experiments ranging from a few seconds to several hours. The final density was maximized at slower heating rates, although processes slower than a certain threshold led to grain growth. The amount of grain growth observed was comparable to a similar conventional thermal process. The bulk electrical conductivity correlated with the maximum temperature and cooling rate. The only property that exhibited behavior that could not be attributed to solely the thermal profile was the grain boundary conductivity, which was consistently higher than conventional in flash sintered samples. These results suggest that, during flash sintering, athermal electric field effects are relegated to the grain boundary. 相似文献
2.
3.
4.
5.
6.
7.
Joshua C. Price Simon J. Levett Valentin Radu David A. Simpson Aina Mogas Barcons Christopher F. Adams Melissa L. Mather 《Small (Weinheim an der Bergstrasse, Germany)》2019,15(22)
Fluorescent nanodiamonds (fNDs) containing nitrogen vacancy (NV) centers are promising candidates for quantum sensing in biological environments. This work describes the fabrication and implementation of electrospun poly lactic‐co‐glycolic acid (PLGA) nanofibers embedded with fNDs for optical quantum sensing in an environment, which recapitulates the nanoscale architecture and topography of the cell niche. A protocol that produces uniformly dispersed fNDs within electrospun nanofibers is demonstrated and the resulting fibers are characterized using fluorescent microscopy and scanning electron microscopy (SEM). Optically detected magnetic resonance (ODMR) and longitudinal spin relaxometry results for fNDs and embedded fNDs are compared. A new approach for fast detection of time varying magnetic fields external to the fND embedded nanofibers is demonstrated. ODMR spectra are successfully acquired from a culture of live differentiated neural stem cells functioning as a connected neural network grown on fND embedded nanofibers. This work advances the current state of the art in quantum sensing by providing a versatile sensing platform that can be tailored to produce physiological‐like cell niches to replicate biologically relevant growth environments and fast measurement protocols for the detection of co‐ordinated endogenous signals from clinically relevant populations of electrically active neuronal circuits. 相似文献
8.
Kazdin Alan E.; Bass Debra; Siegel Todd; Thomas Christopher 《Canadian Metallurgical Quarterly》1989,57(4):522
112 children (aged 7-13 yrs) were randomly assigned to one of three treatments: problem-solving skills training (PSST), problem-solving skills training with in vivo practice (PSST-P), which included therapeutically planned activities to extend training to settings outside of treatment, or client-centered relationship therapy (RT). PSST and PSST-P children showed significantly greater reductions in antisocial behavior and overall behavior problems, and greater increases in prosocial behavior than RT children. These effects were evident on measures obtained immediately after treatment and at a 1-year follow-up, and on measures of child performance at home and at school. PSST-P children showed greater changes than PSST children on measures of functioning at school at posttreatment, but these differences were no longer evident at follow-up. Children in both PSST conditions showed significant reductions in deviant behavior and improvements in prosocial behavior from pretreatment to follow-up, whereas RT children tended to remain at their pretreatment level of functioning. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
9.
Jacob Hooker David Hinks Gerardo Montero Christopher Conlee 《Coloration Technology》2002,118(6):273-276
The synthesis of azo dyes via a conventional aqueous-based diazotisation and coupling reaction requires the use of relatively high concentrations of mineral acids, which leads to high electrolyte concentrations in wastewater. Reported in this paper is an environmentally benign one-pot method for the synthesis of a nonionic azo dye, N,N -diethyl- N -{4-[( E )-(4-nitrophenyl)diazenyl]phenyl}amine, in supercritical carbon dioxide without using a mineral acid. The product yield increased significantly with temperature, with 91% theoretical yield afforded at 80 °C. The pressure of the system had little influence on product yield. 相似文献
10.
Structural engineers use design codes formulated to consider uncertainty for both reinforced concrete and structural steel
design. For a simple one-bay structural steel frame, we survey typical uncertainties and compute an interval solution for
displacements and forces. The naive solutions have large over-estimations, so we explore the Mullen-Muhanna assembly strategy,
scaling, and constraint propagation to achieve tight enclosures of the true ranges for displacements and forces in a fraction
of the CPU time typically used for simulations. That we compute tight enclosures, even for large parameter uncertainties used
in practice, suggests the promise of interval methods for much larger structures. 相似文献