全文获取类型
收费全文 | 327645篇 |
免费 | 25037篇 |
国内免费 | 13195篇 |
专业分类
电工技术 | 19951篇 |
技术理论 | 52篇 |
综合类 | 30242篇 |
化学工业 | 43589篇 |
金属工艺 | 13786篇 |
机械仪表 | 17016篇 |
建筑科学 | 43910篇 |
矿业工程 | 18541篇 |
能源动力 | 10498篇 |
轻工业 | 27259篇 |
水利工程 | 13047篇 |
石油天然气 | 19277篇 |
武器工业 | 4266篇 |
无线电 | 23681篇 |
一般工业技术 | 22226篇 |
冶金工业 | 16608篇 |
原子能技术 | 2010篇 |
自动化技术 | 39918篇 |
出版年
2024年 | 1285篇 |
2023年 | 3793篇 |
2022年 | 7497篇 |
2021年 | 9835篇 |
2020年 | 9783篇 |
2019年 | 6903篇 |
2018年 | 6482篇 |
2017年 | 8393篇 |
2016年 | 10050篇 |
2015年 | 10999篇 |
2014年 | 22520篇 |
2013年 | 18492篇 |
2012年 | 23489篇 |
2011年 | 25498篇 |
2010年 | 19423篇 |
2009年 | 19768篇 |
2008年 | 17815篇 |
2007年 | 22130篇 |
2006年 | 20429篇 |
2005年 | 18092篇 |
2004年 | 15359篇 |
2003年 | 13662篇 |
2002年 | 11026篇 |
2001年 | 9237篇 |
2000年 | 7537篇 |
1999年 | 5852篇 |
1998年 | 4139篇 |
1997年 | 3430篇 |
1996年 | 2784篇 |
1995年 | 2317篇 |
1994年 | 1851篇 |
1993年 | 1311篇 |
1992年 | 1037篇 |
1991年 | 727篇 |
1990年 | 585篇 |
1989年 | 529篇 |
1988年 | 326篇 |
1987年 | 237篇 |
1986年 | 205篇 |
1985年 | 215篇 |
1984年 | 155篇 |
1983年 | 127篇 |
1982年 | 75篇 |
1981年 | 87篇 |
1980年 | 94篇 |
1979年 | 43篇 |
1978年 | 24篇 |
1977年 | 26篇 |
1964年 | 18篇 |
1959年 | 29篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
1.
2.
Wenshu Chen Jiajun Gu Yongping Du Fang Song Fanxing Bu Jinghan Li Yang Yuan Ruichun Luo Qinglei Liu Di Zhang 《Advanced functional materials》2020,30(25)
Large‐scale production of hydrogen from water‐alkali electrolyzers is impeded by the sluggish kinetics of hydrogen evolution reaction (HER) electrocatalysts. The hybridization of an acid‐active HER catalyst with a cocatalyst at the nanoscale helps boost HER kinetics in alkaline media. Here, it is demonstrated that 1T–MoS2 nanosheet edges (instead of basal planes) decorated by metal hydroxides form highly active / heterostructures, which significantly enhance HER performance in alkaline media. Featured with rich / sites, the fabricated 1T–MoS2 QS/Ni(OH)2 hybrid (quantum sized 1T–MoS2 sheets decorated with Ni(OH)2 via interface engineering) only requires overpotentials of 57 and 112 mV to drive HER current densities of 10 and 100 mA cm?2, respectively, and has a low Tafel slope of 30 mV dec?1 in 1 m KOH. So far, this is the best performance for MoS2‐based electrocatalysts and the 1T–MoS2 QS/Ni(OH)2 hybrid is among the best‐performing non‐Pt alkaline HER electrocatalysts known. The HER process is durable for 100 h at current densities up to 500 mA cm?2. This work not only provides an active, cost‐effective, and robust alkaline HER electrocatalyst, but also demonstrates a design strategy for preparing high‐performance catalysts based on edge‐rich 2D quantum sheets for other catalytic reactions. 相似文献
3.
现今国内的数字集群网络发展存在局限性、差异性,还远没有达到“网”状分布的程度,因此,共网数字集群发展空间巨大、前景广阔。通过列举共网数字集群系统在龙嘉国际机场和长春雷锋车队的成功应用案例,探讨了我国共网数字集群系统应用的可行性和必要性。 相似文献
4.
A small handful of recent studies have addressed a phenomenon known as “phantom vibration syndrome”. This refers to when phone users perceive their device to vibrate, indicating that a call or text is incoming, when in fact the phone did not vibrate at all. Though these studies show that most users do not find phantom vibration hallucinations to be very bothersome, they also find that a large majority of users experience this phenomenon. This paper explores what the striking prevalence of phantom vibration syndrome means for our contemporary relationships with technology. I begin with a review of the theories purporting to explain these data, which largely rely on particular understandings of the brain. Next I develop an alternative theory of phantom vibration syndrome based on insights from the philosophical tradition of phenomenology. This account considers the ways users develop bodily and perceptual habits regarding how the phone is understood and used. By critically contrasting these different theories, we can refine our questions about what the high prevalence of phantom vibration syndrome implies about our contemporary technological situation. 相似文献
5.
Rectangular section control technology(RSCT)was introduced to achieve high-precision profile control during silicon steel rolling.The RSCT principle and method were designed,and the whole RSCT control strategy was developed.Specifically,RSCT included roll contour design,rolling technology optimization,and control strategy development,aiming at both hot strip mills(HSMs)and cold strip mills(CSMs).Firstly,through the high-performance variable crown(HVC)work roll optimization design in the upper-stream stands and the limited shifting technology for schedule-free rolling in the downstream stands of HSMs,a hot strip with a stable crown and limited wedge,local spot,and single wave was obtained,which was suitable for cold rolling.Secondly,an approximately rectangular section was obtained by edge varying contact(EVC)work roll contour design,edge-drop setting control,and closed loop control in the upper-stream stands of CSMs.Moreover,complex-mode flatness control was realized by coordinating multiple shape-control methods in the downstream stands of CSMs.In addition,the RSCT approach was applied in several silicon-steel production plants,where an outstanding performance and remarkable economic benefits were observed. 相似文献
6.
《Food Control》2015
The aim of the study was to investigate annual and regional differences in the level of aflatoxin B1 (AFB1) in grains and dairy cattle feed. Maize (n = 972), wheat (n = 201), barley (n = 147), oat (n = 136), grain mixtures (n = 168), and dairy cattle feed (n = 325) were sampled from 2009 to 2013 on different farms and in different farm factories situated in four Croatian regions. The samples were analysed for AFB1 using the validated ELISA immunoassay. AFB1 was determined in 16.4% of all investigated samples, among which maize was proven to be the most contaminated, with 21.7% of the samples recovered during 2013 harbouring AFB1 in concentrations over the permissible ones. Levels higher than permitted were observed in 17.9% and 12.3% of grain mixtures and dairy cattle feed, respectively, whereas concentrations of AFB1 determined in other crops throughout the investigated period met the stipulated requirements. The results revealed the AFB1 occurrence to be significantly (p < 0.05) dependent on the cultivation region, with the highest levels generally found in maize harvested in 2013 and consequently in grain mixtures and cattle feed that can most likely be associated with climatic conditions as the most critical factor for mould formation, and thus also AFB1 production. 相似文献
7.
为检查工程质量,查找输水系统可能存在的问题并消除隐患,保障电站安全运行,福建仙游抽水蓄能电站在投产发电前,要对输水发电系统进行充水试验与放空排水试验,在试验过程中监测输水系统的应力、应变与渗漏水情况。本文以尾水系统为例,介绍了试验所应具备的工程条件、工作程序及技术要求、试验成果分析和存在问题处理等。试验表明,仙游抽水蓄能电站尾水系统设计合理,施工质量优良,结构可靠,可供同类工程参考与借鉴。 相似文献
8.
9.
文章通过对黑龙江省高效节水现状,存在问题的分析,结合黑龙江省高效节水发展的支撑能力,阐述黑龙江省节水增粮目标、任务及总体布局,为黑龙江省2012—2015年节水增粮实施提供依据。 相似文献
10.