首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   1640131篇
  免费   36656篇
  国内免费   11984篇
电工技术   41262篇
技术理论   11篇
综合类   13632篇
化学工业   290426篇
金属工艺   71145篇
机械仪表   51252篇
建筑科学   55580篇
矿业工程   15352篇
能源动力   53139篇
轻工业   126106篇
水利工程   17304篇
石油天然气   45309篇
武器工业   1226篇
无线电   208633篇
一般工业技术   301158篇
冶金工业   178610篇
原子能技术   35083篇
自动化技术   183543篇
  2022年   13623篇
  2021年   20179篇
  2020年   15363篇
  2019年   17413篇
  2018年   19418篇
  2017年   19220篇
  2016年   24809篇
  2015年   21933篇
  2014年   33974篇
  2013年   94150篇
  2012年   43622篇
  2011年   57326篇
  2010年   49967篇
  2009年   57535篇
  2008年   52394篇
  2007年   49692篇
  2006年   51967篇
  2005年   45739篇
  2004年   45281篇
  2003年   44941篇
  2002年   43755篇
  2001年   40512篇
  2000年   38851篇
  1999年   38169篇
  1998年   49861篇
  1997年   42731篇
  1996年   38120篇
  1995年   32798篇
  1994年   30487篇
  1993年   29906篇
  1992年   27199篇
  1991年   24092篇
  1990年   24271篇
  1989年   23259篇
  1988年   21781篇
  1987年   19946篇
  1986年   19335篇
  1985年   22587篇
  1984年   22676篇
  1983年   20615篇
  1982年   19445篇
  1981年   19564篇
  1980年   18125篇
  1979年   18738篇
  1978年   17914篇
  1977年   17712篇
  1976年   19010篇
  1975年   16131篇
  1974年   15692篇
  1973年   15746篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
992.
993.
994.
Journal of Mechanical Science and Technology - A multi-robot collaborative towing system fixed on floating base for high load marine work was established in this paper, and its dynamics and...  相似文献   
995.
996.
Itaconate (ITA) is an emerging powerhouse of innate immunity with therapeutic potential that is limited in its ability to be administered in a soluble form. A library of polyester materials that incorporate ITA into polymer backbones resulting in materials with inherent immunoregulatory behavior is developed. Harnessing hydrolytic degradation release from polyester backbones, ITA polymers result in the mechanism specific immunoregulatory properties on macrophage polarization in vitro. In a functional assay, the polymer-released ITA inhibits bacterial growth on acetate. Translation to an in vivo model of biomaterial associated inflammation, intraperitoneal injection of ITA polymers demonstrate a rapid resolution of inflammation in comparison to a control polymer silicone, demonstrating the value of sustained biomimetic presentation of ITA.  相似文献   
997.
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   
998.
Monolithically-integrated tandem photoanodes were fabricated on substrates consisting of epitaxial n-GaAs1-xPx (x ? 0.32) grown on n+-GaAs wafers. A p+-n junction photovoltaic (PV) cell was first formed by zinc diffusion into the n-GaAs0.68P0.32 from a deposited ZnO coating. After diffusion the ZnO serves as a transparent electrical contact to the resulting p+-GaAs0.68P0.32 surface layer. Transparent, conducting SnO2:F provides chemical and mechanical protection for the ZnO and the underlying PV cell, and it electrically connects this cell to a top BiVO4 photocatalyst layer. In some photoanodes, a WO3 thin film was interposed between the SnO2:F and BiVO4. All oxide coatings were produced by ultrasonic spray pyrolysis except WO3, which was spin coated. Unassisted (unbiased) solar water splitting was achieved, with a solar-to-hydrogen efficiency approaching 2%, without addition of any co-catalyst to the BiVO4 surface. This work can provide insights to other researchers regarding scalable, low cost approaches for the planar monolithic integration of oxide photoanode materials with PV cells to create new tandem devices.  相似文献   
999.
Beardless barb is a common fish species used in fermentation of fish paste Ka-pi-plaa. Autolytic profile of beardless barb muscle showed the maximum autolysis was at 50 °C, at both acidic and alkaline pH values. With augmentation concentration of NaCl, autolytic activity slightly decreased. Endogenous proteinases isolated from fish muscle in crude extract forms were also characterised. The acidic proteinases had optimum activity at pH 3.0 and 50°C, and they showed higher proteolytic activity than the alkaline proteinases which were optimally active at pH 9.0 and 50 °C. Proteinases in peak at pH 3.0 were inhibited by pepstatin A, but those in peak at pH 9.0 were highly inhibited by PMSF, TLCK and soybean trypsin inhibitor, suggesting that both aspartic and serine proteinases were existed in beardless barb muscle. The proteinases were stable in pH range of 2.0-5.0 but unstable at the temperatures higher than 40 °C. NaCl suppressed the proteolytic activity, ATP activated the proteinase activity, while CaCl2, MgCl2 and CoCl2 exhibited no influence on the activity. The results implied that cathepsin D is the predominant proteinase responsible for autolysis in beardless barb. The findings were useful to improve the processing and qualities of Ka-pi-plaa product using beardless barb as raw material.  相似文献   
1000.
赵玮 《今日消防》2021,6(12):121-123
近年来,科技发展持续发展,人们的生活愈加富足.城市化进程不断加快,各种市场主体层出不穷,对消防监测培训工作提出更高的要求.在如今多媒体信息智能时代,如何逐步改进防火监测工作,通过先进信息手段提高防火监测工作的实效和成果,是防火部门始终摸索和研讨的问题.文章主要研究了当前防火监测管理任务中存在的弊端,深入研究了信息时代防火监测工作的改进举措,并为现代防火监测培训工作提出一些建议.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号