全文获取类型
收费全文 | 53574篇 |
免费 | 6173篇 |
国内免费 | 2553篇 |
专业分类
电工技术 | 3766篇 |
技术理论 | 3篇 |
综合类 | 3602篇 |
化学工业 | 6339篇 |
金属工艺 | 3182篇 |
机械仪表 | 3153篇 |
建筑科学 | 4405篇 |
矿业工程 | 2308篇 |
能源动力 | 3802篇 |
轻工业 | 4624篇 |
水利工程 | 2070篇 |
石油天然气 | 2912篇 |
武器工业 | 505篇 |
无线电 | 4210篇 |
一般工业技术 | 6259篇 |
冶金工业 | 2957篇 |
原子能技术 | 852篇 |
自动化技术 | 7351篇 |
出版年
2024年 | 475篇 |
2023年 | 1963篇 |
2022年 | 2220篇 |
2021年 | 2751篇 |
2020年 | 2901篇 |
2019年 | 2390篇 |
2018年 | 2188篇 |
2017年 | 2550篇 |
2016年 | 2757篇 |
2015年 | 2844篇 |
2014年 | 3900篇 |
2013年 | 5074篇 |
2012年 | 3434篇 |
2011年 | 3342篇 |
2010年 | 2667篇 |
2009年 | 2615篇 |
2008年 | 2185篇 |
2007年 | 2339篇 |
2006年 | 2159篇 |
2005年 | 1883篇 |
2004年 | 1625篇 |
2003年 | 1423篇 |
2002年 | 1142篇 |
2001年 | 940篇 |
2000年 | 834篇 |
1999年 | 685篇 |
1998年 | 498篇 |
1997年 | 407篇 |
1996年 | 355篇 |
1995年 | 299篇 |
1994年 | 274篇 |
1993年 | 208篇 |
1992年 | 163篇 |
1991年 | 130篇 |
1990年 | 127篇 |
1989年 | 97篇 |
1988年 | 66篇 |
1987年 | 58篇 |
1986年 | 33篇 |
1985年 | 36篇 |
1984年 | 42篇 |
1983年 | 20篇 |
1982年 | 22篇 |
1981年 | 16篇 |
1980年 | 20篇 |
1979年 | 9篇 |
1977年 | 11篇 |
1976年 | 13篇 |
1964年 | 15篇 |
1959年 | 12篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
11.
《International Journal of Industrial Ergonomics》2014,44(5):747-752
The purpose of this study is to validate an analytical method in assessing demanded mental workloads for physical therapists, and to discuss its possible ergonomics implications on the design of healthcare working systems in which physical therapists are considered as the users. A task analysis was first used to understand the operation steps of three identified physical therapies. Then, the McCracken–Aldrich technique was applied to assign ratings of mental workload demanded for performing each step of the therapies. Finally, the assigned ratings were validated by the analysis of correlation with the answers of the NASA-TLX questionnaire collected from seventeen physical therapists in the rehabilitation center of a university-affiliated hospital. Results showed that the proposed McCracken–Aldrich technique was suitable as an analysis tool for predicting metal workloads of physical therapists. Some possible implications about the information provision and user interface design for reducing therapists' mental workloads on current therapy operations were discussed.Relevance to industryResults of this paper are expected to contribute the research and development in healthcare industry on its system design and workflow analysis. 相似文献
12.
A novel sol–gel method based on V2O5·nH2O hydro-gel was developed to synthesize nanocrystalline Li3V2(PO4)3/carbon composite material. In this route, V2O5·nH2O hydro-gel, NH4H2PO4, Li2CO3 and high-surface-area carbon were used as starting materials to prepare precursor, and the Li3V2(PO4)3/carbon was obtained by sintering precursor at 750 °C for 4 h in flowing argon. The sol–gel synthesis ensures homogeneity of the precursors and improved reactivity. The sample was characterized by XRD, SEM and TEM. X-ray diffraction results show Li3V2(PO4)3 sample is monoclinic structure with the space group of P21/n. The TEM image indicates that the Li3V2(PO4)3 particles modified by conductive carbon are about 70 nm in diameter. The Li3V2(PO4)3/carbon system showed that the discharge capacities in the first and 50th cycle are about 155.3 and 143.6 mAh/g, respectively, in the range of 3.0–4.8 V. The sol–gel method is fit for the preparation of Li3V2(PO4)3/carbon composite material which may offer some favorable properties for commercial application. 相似文献
13.
Xiaoxiang Hu Changhua Hu Zhaoqiang Wang Huijun Gao 《International journal of systems science》2014,45(8):1740-1756
By utilising Takagi–Sugeno (T–S) fuzzy set approach, this paper addresses the robust H∞ dynamic output feedback control for the non-linear longitudinal model of flexible air-breathing hypersonic vehicles (FAHVs). The flight control of FAHVs is highly challenging due to the unique dynamic characteristics, and the intricate couplings between the engine and fight dynamics and external disturbance. Because of the dynamics’ enormous complexity, currently, only the longitudinal dynamics models of FAHVs have been used for controller design. In this work, T–S fuzzy modelling technique is utilised to approach the non-linear dynamics of FAHVs, then a fuzzy model is developed for the output tracking problem of FAHVs. The fuzzy model contains parameter uncertainties and disturbance, which can approach the non-linear dynamics of FAHVs more exactly. The flexible models of FAHVs are difficult to measure because of the complex dynamics and the strong couplings, thus a full-order dynamic output feedback controller is designed for the fuzzy model. A robust H∞ controller is designed for the obtained closed-loop system. By utilising the Lyapunov functional approach, sufficient solvability conditions for such controllers are established in terms of linear matrix inequalities. Finally, the effectiveness of the proposed T–S fuzzy dynamic output feedback control method is demonstrated by numerical simulations. 相似文献
14.
Visualization of pathlines is common and highly relevant for the analysis of unsteady flow. However, pathlines can intersect, leading to visual clutter and perceptual issues. This makes it intrinsically difficult to provide expressive visualizations of the entire domain by an arrangement of multiple pathlines, in contrast to well‐established streamline placement techniques. We present an approach to reduce these problems. It is inspired by glyph‐based visualization and small multiples: we partition the domain into cells, each corresponding to a downscaled version of the entire domain. Inside these cells, a single downscaled pathline is drawn. On the overview scale, our pathline glyphs lead to emergent visual patterns that provide insight into time‐dependent flow behavior. Zooming‐in allows us to analyze individual pathlines in detail and compare neighboring lines. The overall approach is complemented with a context‐preserving zoom lens and interactive pathline‐based exploration. While we primarily target the visualization of 2D flow, we also address the extension to 3D. Our evaluation includes several examples, comparison to other flow visualization techniques, and a user study with domain experts. 相似文献
15.
罗琳 《包头钢铁学院学报》2009,28(4):374-376,385
面对社会对职业技术的日益重视,职业技术学校的发展也有了日新月异的变化.试图通过对鹤壁职业技术学院新校区的规划设计与分析,探讨当代教育理念与模式下高等职业技术教育的办学特色和校园文化对规划及建筑设计的影响,从而总结适应职业技术教育的设计理念和方法,塑造具有自身特色和体现城市风貌的职业技术学院. 相似文献
16.
LIU JunFeng & FENG YuJie State Key Laboratory of Urban Water Resource Environment Harbin Institute of Technology Harbin China 《中国科学E辑(英文版)》2009,(6)
SnO2 electrodes have many advantages in the degradation of toxic or bio-refractory organic wastewater,and SnO2 is a kind of anode material which has the potential to be widely used.Electrocatalytic effi-ciency and service life of Ti\SnO2 electrodes are key factors that can influence its applications.In order to enhance the electrocatalytic characteristics of Ti\SnO2 electrodes,a type of electrocatalytic electrode with nanocoating was prepared by direct current(DC)electrodeposition method and thermal oxidati... 相似文献
17.
冯洁茹 《空军雷达学院学报》2008,22(1):75-78
从真实性的角度出发,利用Bachman的任务特征框架分析了NETEM阅读理解部分对考生交际语言能力的测试.分析表明,NETEM在输入材料方面有较高的真实性,任务涉及的语言能力的真实性也有很大的提高.但从输入与回答之间的关系看,个别题目未能体现交际语言能力的特点,仍有待改进. 相似文献
18.
19.
采用介质阻挡放电(DBD)降解常压下流动态的邻二甲苯模拟废气,系统地考察了放电极值电压,气体的初始质量浓度、停留时间以及相对湿度等工艺参数对邻二甲苯降解的影响,并初步探讨了邻二甲苯的降解产物.实验研究结果表明:在7.0kV的放电极间电压下,邻二甲苯的初始质量浓度为1 500mg/m3,停留时间为9s,其去除率可达到80%以上.降解产物主要为CO2、H2O以及苯甲酸、苯乙酸、苯乙醛等有机物,并且经降解后产物的生物可生化性得到提高,因而为后续的等离子-生物法联合处理VOCs提供了依据. 相似文献
20.
王佳娣 《湖南纺织高等专科学校学报》2014,(3):36-38
明末清初,西方来华传教士将翻译作为“学术传教”的一种手段,将大量的西方宗教和科技著作译介入中国,同时将中国古代典籍和文献著作等输出至西方,形成了“西学东渐”和“东学西传”并存的局面。客观上,这是中西方政治、经济和文化的发展的必然结果;主观上,这与传教士自身的人格魅力和知识素养有着紧密的联系。 相似文献