全文获取类型
收费全文 | 250819篇 |
免费 | 26816篇 |
国内免费 | 17120篇 |
专业分类
电工技术 | 24584篇 |
技术理论 | 14篇 |
综合类 | 28279篇 |
化学工业 | 19602篇 |
金属工艺 | 10227篇 |
机械仪表 | 17568篇 |
建筑科学 | 22959篇 |
矿业工程 | 9070篇 |
能源动力 | 8753篇 |
轻工业 | 9680篇 |
水利工程 | 8717篇 |
石油天然气 | 11855篇 |
武器工业 | 3261篇 |
无线电 | 24168篇 |
一般工业技术 | 24294篇 |
冶金工业 | 7726篇 |
原子能技术 | 3344篇 |
自动化技术 | 60654篇 |
出版年
2024年 | 483篇 |
2023年 | 2943篇 |
2022年 | 5772篇 |
2021年 | 7120篇 |
2020年 | 7746篇 |
2019年 | 6513篇 |
2018年 | 6033篇 |
2017年 | 7818篇 |
2016年 | 8764篇 |
2015年 | 9758篇 |
2014年 | 15814篇 |
2013年 | 14558篇 |
2012年 | 19021篇 |
2011年 | 20118篇 |
2010年 | 15515篇 |
2009年 | 15788篇 |
2008年 | 15508篇 |
2007年 | 18372篇 |
2006年 | 15964篇 |
2005年 | 13866篇 |
2004年 | 11520篇 |
2003年 | 9986篇 |
2002年 | 8132篇 |
2001年 | 6677篇 |
2000年 | 5624篇 |
1999年 | 4528篇 |
1998年 | 3553篇 |
1997年 | 3035篇 |
1996年 | 2577篇 |
1995年 | 2348篇 |
1994年 | 1938篇 |
1993年 | 1434篇 |
1992年 | 1189篇 |
1991年 | 911篇 |
1990年 | 733篇 |
1989年 | 674篇 |
1988年 | 495篇 |
1987年 | 309篇 |
1986年 | 252篇 |
1985年 | 210篇 |
1984年 | 179篇 |
1983年 | 170篇 |
1982年 | 148篇 |
1981年 | 111篇 |
1980年 | 68篇 |
1979年 | 85篇 |
1978年 | 44篇 |
1977年 | 46篇 |
1976年 | 35篇 |
1959年 | 43篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
11.
对于机械设备的故障运行问题,技术人员应当深入研究机械设备的故障规律,并研究出运行趋势的预测方法,从传感器的检测时间间隔与使用数量等方面加以深入的研究。本文介绍了机械设备运行状态的故障预测方法,并将机械设备运行状态的故障预测方法总结为三个步骤,分别是数据获取、处理与设备寿命预测,结合这些内容,提出了关于机械设备故障运行的一些方法,旨在为相关技术人员提供参考依据。 相似文献
12.
Ashish Ganvir Mohit Gupta Nitish Kumar Nicolaie Markocsan 《Ceramics International》2021,47(1):272-283
This paper investigates the influence of suspension characteristics on microstructure and performance of suspensions plasma sprayed (SPS) thermal barrier coatings (TBCs). Five suspensions were produced using various suspension characteristics, namely, type of solvent and solid load content, and the resultant suspensions were utilized to deposit five different TBCs under identical processing conditions. The produced TBCs were evaluated for their performance i.e. thermal conductivity, thermal cyclic fatigue (TCF) and thermal shock (TS) lifetime. This experimental study revealed that the differences in the microstructure of SPS TBCs produced using varied suspensions resulted in a wide-ranging overall TBC performance. All TBCs exhibited thermal conductivity lower than 1 W/(m. K) except water-ethanol mixed suspension produced TBC. The TS lifetime was also affected to a large extent where 10 wt % solid loaded ethanol and 25 wt % solid loaded water suspensions produced TBCs exhibited the highest and the lowest lifetime, respectively. On the contrary, TCF lifetime was not as significantly affected as thermal conductivity and TS lifetime, and all ethanol suspensions showed marginally better TCF lifetime than water and ethanol-water mixed suspensions deposited TBCs. 相似文献
13.
This paper analyses the perception of Artificial Intelligence (AI) by individuals in Spain and the factors associated with it. It uses data from 6308 individuals from a 2018 Spanish survey. A binary logit regression model is formulated and estimated for the attitude towards robots and AI and its possible determinants. As main results are that a gender gap is detected, and that people have a negative attitude if they are not interested in scientific discoveries and technological developments and if AI and robots are not useful at work. 相似文献
14.
15.
采用有限元模拟和实验研究了挤压钛合金弯曲管件。通过实验验证了工件的形状和尺寸精度,并通过有限元模拟分析了工艺参数对挤出过程中变形体的平均压应力分布情况和挤出弯管件的曲率半径的影响规律。结果表明:有限元模拟中,弯管件的曲率半径误差为6.03%,弯管直径误差为3.82%;在靠近定径带处,平均压应力呈非均匀分布;在焊合腔内,靠近细分流孔区域的平均压应力小于靠近粗分流孔区域的平均压应力,平均压应力的大小顺序在通过粗、细分流孔前后相反;在模具结构固定不变时,弯管件的曲率半径随挤压速度的减小而增大,不随挤压温度的变化而变化。 相似文献
16.
17.
The ways in which environmental priorities are framed are varied and influenced by political forces. One technological advance--the proliferation of government open data portals (ODPs)--has the potential to improve governance through facilitating access to data. Yet it is also known that the data hosted on ODPs may simply reflect the goals and interests of multiple levels of political power. In this article, I use traditional statistical correlation and regression techniques along with newer natural language processing and machine learning algorithms to analyze the corpus of datasets hosted on government ODPs (total: 49,066) to extract patterns that relate scales of governance and political liberalism/conservatism to the priorities and meaning attached to environmental issues. I find that state-level and municipal-level ODPs host different categories of environmental datasets, with municipal-level ODPs generally hosting more datasets pertaining to services and amenities and state-level ODPs hosting more datasets pertaining to resource protection and extraction. Stronger trends were observed for the influences of political conservatism/liberalism among state-level ODPs than for municipal-level ODPs. 相似文献
18.
19.
20.
Yu-Xuan Li Ping Li Yu-Zhe Wu Zhen-Liang Xu Ming-Ling Huang 《Ceramics International》2021,47(2):2180-2186
A novel TiO2 thin film was prepared on the ceramic hollow fiber by the sol-gel method using poly(vinylpyrrolidone) (PVP) and polyvinyl alcohol (PVA) as additives. SEM images verified the formation of TiO2 layer with various thickness using different composition of titania sols. The effect of the PVP and PVA contents on the TiO2 sol properties, the separation and the antifouling performance of the ultrafiltration membranes were investigated thoroughly. When the contents of PVP and PVA were 1.0 wt% and 0.8 wt%, respectively, the resultant membrane showed a thickness of 0.55 μm with a pure water flux of 255 L m?2 h?1. In addition, the adherent foulant bovine serum albumin was applied to evaluate the antifouling performance. During the three fouling-recovery cycles, the flux recovery ratio and the flux decay ratio maintained about 99% and 30%. The BSA flux and rejection were still 169 L m?2 h?1 and 96.9% after the cycles, indicating a superior antifouling property. 相似文献