全文获取类型
收费全文 | 1579篇 |
免费 | 182篇 |
国内免费 | 111篇 |
专业分类
电工技术 | 213篇 |
综合类 | 136篇 |
化学工业 | 158篇 |
金属工艺 | 55篇 |
机械仪表 | 248篇 |
建筑科学 | 184篇 |
矿业工程 | 17篇 |
能源动力 | 81篇 |
轻工业 | 64篇 |
水利工程 | 74篇 |
石油天然气 | 6篇 |
武器工业 | 4篇 |
无线电 | 184篇 |
一般工业技术 | 92篇 |
冶金工业 | 81篇 |
原子能技术 | 10篇 |
自动化技术 | 265篇 |
出版年
2024年 | 11篇 |
2023年 | 28篇 |
2022年 | 58篇 |
2021年 | 75篇 |
2020年 | 67篇 |
2019年 | 35篇 |
2018年 | 45篇 |
2017年 | 53篇 |
2016年 | 59篇 |
2015年 | 61篇 |
2014年 | 147篇 |
2013年 | 114篇 |
2012年 | 136篇 |
2011年 | 143篇 |
2010年 | 101篇 |
2009年 | 136篇 |
2008年 | 79篇 |
2007年 | 88篇 |
2006年 | 76篇 |
2005年 | 79篇 |
2004年 | 68篇 |
2003年 | 43篇 |
2002年 | 38篇 |
2001年 | 24篇 |
2000年 | 27篇 |
1999年 | 14篇 |
1998年 | 11篇 |
1997年 | 14篇 |
1996年 | 7篇 |
1995年 | 5篇 |
1994年 | 3篇 |
1993年 | 4篇 |
1992年 | 2篇 |
1991年 | 2篇 |
1990年 | 2篇 |
1988年 | 5篇 |
1987年 | 3篇 |
1986年 | 2篇 |
1985年 | 2篇 |
1983年 | 1篇 |
1980年 | 1篇 |
1978年 | 1篇 |
1964年 | 1篇 |
1957年 | 1篇 |
排序方式: 共有1872条查询结果,搜索用时 62 毫秒
91.
连铸连轧过程中SPA-H钢板表面的氧化锈蚀 总被引:1,自引:0,他引:1
利用光学显微镜、扫描电镜、能谱和XRD衍射物相分析等手段,研究了SPA-H钢经连铸连轧后表面黄色锈斑的形成原因.结果表明,黄色锈斑的外层主要由Fe2O3、里层由FeO组成,在钢板表面呈条带状分布;而无黄色锈斑的钢板表面主要是由FeO组成.黄色锈斑是由于在轧制过程中,钢表面的高温氧化产物(FeO)破裂,在随后的冷却过程中破裂处特别是裂纹的尖端形成大量的Fe2O3所致,高温氧化产物FeO的应变速率和该氧化膜的横向生长比较高,高温氧化膜开裂后,裂纹不能自愈,较低温度时合金表面发生了线性氧化. 相似文献
92.
山区送电线路设计思路探讨 总被引:1,自引:0,他引:1
该文对110kV扶隆至东乡送电线路工程建设规模、设计的难点和特点进行了介绍,并借鉴其它送电线路设计和施工的成功经验,对山区送电线路的勘察设计从路径选择、气象条件选择、防雷设计杆型选用以及陡坡地带塔基处理提出了相应设计思路。 相似文献
93.
94.
气象数据缺测条件下参照腾发量的计算方法 总被引:55,自引:1,他引:55
利用河北雄县和望都两气象站的数据,对FAO推荐的气象数据缺测时参照腾发量的计算方法进行了检验和评价,分析了参照腾发量对各气象要素的敏感性,提出了在气象数据缺测条件下适应我国北方平原区气候条件的参照腾发量的计算方法。 相似文献
95.
96.
水泥混凝土路面是典型的板状结构,浇筑时混凝土的温度、基层温度、模板温度、环境温度、相对湿度以及风速等对混凝土的浇筑、压实、饰面以及长期路用性能影响较大.低温条件对早期混凝土质量如工作性、凝结时间和早期强度以及体积稳定性和耐久性的影响不可忽视.在总结低温条件对混凝土质量影响的基础上,认为控制混凝土的浇筑温度和浇筑后数日的养护温度对路面的长期性能至关重要.对目前通常采用的控制混凝土浇筑时温度的措施如改善配合比、提高混凝土组分温度、掺加特种外加剂和采取合理的养护措施等作了详细介绍. 相似文献
97.
98.
R. Yaari G. Katriel A. Huppert J. B. Axelsen L. Stone 《Journal of the Royal Society Interface》2013,10(84)
Seasonal influenza appears as annual oscillations in temperate regions of the world, yet little is known as to what drives these annual outbreaks and what factors are responsible for their inter-annual variability. Recent studies suggest that weather variables, such as absolute humidity, are the key drivers of annual influenza outbreaks. The rapid, punctuated, antigenic evolution of the influenza virus is another major factor. We present a new framework for modelling seasonal influenza based on a discrete-time, age-of-infection, epidemic model, which allows the calculation of the model''s likelihood function in closed form. This framework may be used to perform model inference and parameter estimation rigorously. The modelling approach allows us to fit 11 years of Israeli influenza data, with the best models fitting the data with unusually high correlations in which r > 0.9. We show that using actual weather to modulate influenza transmission rate gives better results than using the inter-annual means of the weather variables, providing strong support for the role of weather in shaping the dynamics of influenza. This conclusion remains valid even when incorporating a more realistic depiction of the decay of immunity at the population level, which allows for discrete changes in immunity from year to year. 相似文献
99.
Detailed and reliable spatiotemporal characterizations of turbine hub height wind fields over coastal and offshore regions are becoming imperative for the global wind energy industry. Contemporary wind resource assessment frameworks incorporate diverse multiscale prognostic models (commonly known as mesoscale models) to dynamically downscale global‐scale atmospheric fields to regional‐scale (i.e., spatial and temporal resolutions of a few kilometers and a few minutes, respectively). These high‐resolution model solutions aim at depicting the expected wind behavior (e.g., wind shear, wind veering and topographically induced flow accelerations) at a particular location. Coastal and offshore regions considered viable for wind power production are also known to possess complex atmospheric flow phenomena (including, but not limited to, coastal low‐level jets (LLJs), internal boundary layers and land breeze–sea breeze circulations). Unfortunately, the capabilities of the new‐generation mesoscale models in realistically capturing these diverse flow phenomena are not well documented in the literature. To partially fill this knowledge gap, in this paper, we have evaluated the performance of the Weather Research and Forecasting model, a state‐of‐the‐art mesoscale model, in simulating a series of coastal LLJs. Using observational data sources we explore the importance of coastal LLJs for offshore wind resource estimation along with the capacity to which they can be numerically simulated. We observe model solutions to demonstrate strong sensitivities with respect to planetary boundary layer parameterization and initialization conditions. These sensitivities are found to be responsible for variability in AEP estimates by a factor of two. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
100.
Noting the presumed tradeoff between diversity and performance goals in contemporary selection practice, the authors elaborate on recruiting-based methods for avoiding adverse impact while maintaining aggregate individual productivity. To extend earlier work on the primacy of applicant pool characteristics for resolving adverse impact, they illustrate the advantages of simultaneous cognitive ability– and personality-based recruiting. Results of an algebraic recruiting model support general recruiting for cognitive ability, combined with recruiting for conscientiousness within the underrepresented group. For realistic recruiting effect sizes, this type of recruiting strategy greatly increases average performance of hires and percentage of hires from the underrepresented group. Further results from a policy-capturing study provide initial guidance on how features of organizational image can attract applicants with particular job-related personalities and abilities, in addition to attracting applicants on the basis of demographic background. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献