全文获取类型
收费全文 | 1618篇 |
免费 | 211篇 |
国内免费 | 82篇 |
专业分类
电工技术 | 201篇 |
综合类 | 196篇 |
化学工业 | 88篇 |
金属工艺 | 20篇 |
机械仪表 | 69篇 |
建筑科学 | 147篇 |
矿业工程 | 73篇 |
能源动力 | 61篇 |
轻工业 | 19篇 |
水利工程 | 64篇 |
石油天然气 | 40篇 |
武器工业 | 52篇 |
无线电 | 107篇 |
一般工业技术 | 77篇 |
冶金工业 | 408篇 |
原子能技术 | 17篇 |
自动化技术 | 272篇 |
出版年
2024年 | 7篇 |
2023年 | 27篇 |
2022年 | 52篇 |
2021年 | 45篇 |
2020年 | 59篇 |
2019年 | 40篇 |
2018年 | 47篇 |
2017年 | 50篇 |
2016年 | 50篇 |
2015年 | 49篇 |
2014年 | 70篇 |
2013年 | 66篇 |
2012年 | 98篇 |
2011年 | 123篇 |
2010年 | 93篇 |
2009年 | 131篇 |
2008年 | 130篇 |
2007年 | 144篇 |
2006年 | 143篇 |
2005年 | 95篇 |
2004年 | 82篇 |
2003年 | 67篇 |
2002年 | 51篇 |
2001年 | 37篇 |
2000年 | 18篇 |
1999年 | 21篇 |
1998年 | 12篇 |
1997年 | 9篇 |
1996年 | 5篇 |
1995年 | 2篇 |
1994年 | 5篇 |
1993年 | 4篇 |
1992年 | 3篇 |
1991年 | 3篇 |
1990年 | 2篇 |
1987年 | 2篇 |
1972年 | 1篇 |
1966年 | 3篇 |
1965年 | 3篇 |
1964年 | 9篇 |
1963年 | 9篇 |
1962年 | 3篇 |
1961年 | 5篇 |
1960年 | 3篇 |
1959年 | 6篇 |
1958年 | 2篇 |
1957年 | 5篇 |
1956年 | 2篇 |
1955年 | 8篇 |
1954年 | 6篇 |
排序方式: 共有1911条查询结果,搜索用时 15 毫秒
91.
92.
93.
Sankaran Durairaj 《Chemical engineering science》2009,64(7):1488-1502
A detailed theoretical analysis has been carried out to study the role of ceramic supports (alumina and SiC) and pulsed microwave heating of polymer (Natural Rubber, NR, and Nylon 66) slabs due to various distributions of microwave incidences. Ceramic plates are typical representations as they withstand high temperature without any deformation. It is found that ceramic plates influence the heating processes significantly and local hot spots within samples are governed by specific type of ceramic plates for various sample thicknesses and distributions of microwave incidence (one side or both sides). Optimized pulsing of microwave incidence has been employed to minimize the thermal runaway or hot spots in order to achieve uniform temperature distribution and pulsing is introduced based on two parameters: setpoint (ΔTS) and on-off constraint (T′). Detailed spatial distributions of power and temperature are illustrated for a few representative length scales to demonstrate the role of local maxima in power and temperature on heating rate as well as thermal runaway with or without pulsing. Pulsing ratio (PR) has been defined as PR=toff/tp, where toff is power-off time and tp is the total processing time such that smaller PR denotes large processing rates. It is found that one side incidence gives smaller values of PR for both the ceramic plates whereas SiC plate may be suitable for both sides incidence with large sample thicknesses of NR samples. It is also found that larger values of setpoints also minimize PR. The setpoints along with the on-off constraint play critical role to select the heating strategy as a function of ceramic plates and types of incidence. Pulsing may not be important for smaller thicknesses of Nylon samples and SiC or alumina plates may be recommended for processing larger thicknesses of Nylon samples in presence of pulsing. Current study recommends the efficient microwave heating methodologies for polymer processing attached with ceramic plates by means of optimized pulsing for the first time. 相似文献
94.
数控机床设备的选择是一个具有多层次、多因素且定量与定性指标并存的选择问题,考虑到决策者决策的模糊性,提出一种基于模糊层次分析法( fuzzy analytic hierarchy process,FAHP)的多目标决策问题的解决方案。从质量属性、经济属性、环境属性、人机属性四个方面建立指标评价体系,根据指标权重、指标值得分和可行性方案得分确定最优方案。最后通过一个实例分析表明FAHP在数控机床设备选择中的优越性。 相似文献
95.
Safety aspects in modelling of batch and semibatch stirred tank reactors as well as a model based safety analysis have been considered. Applicability of two basic types of models – i.e. the perfectly mixed reactor model and the CFD model, both formulated for laboratory scale as well as pilot plant scale reactors – has been discussed. A formulation of the appropriate reactor model, which is adequate to the considered case study has been demonstrated and tested experimentally. Particular attention has been devoted to the formulation of robust CFD models employed to simulate a performance of the stirred tank reactors. It has been found that models for perfectly mixed reactors may have quite wide range of application, while the CFD models should be definitely used in case of fast reactions, high viscosity of the reacting mixture as well as of failure leading to stopping of the impeller. The CFD models are able to predict a dynamic behaviour of reactors at any circumstances, so they can play a significant role in safety analysis carried out for industrial scale reactors, for which experimental safety tests are expensive and dangerous. 相似文献
96.
97.
短周期电弧螺柱焊生产效率高,易于实现自动化,广泛应用于汽车工业。开发了由信号采集单元和分析软件构成的短周期螺柱焊在线分析系统。信号采集单元包含PIC18F4580单片机、电源、信号调理、外部存储器和RS485通信等电路,通过焊接状态判断、AD采样、数据存储和通信等程序,实现焊接电流和电压采集、存储和传输。分析软件采用Microsoft Visual Studio C#编写,操作界面由主窗口、焊接过程分析窗口、熔深阈值设置窗口和报警窗口等构成。DP600镀锌钢板焊接试验表明,开发的短周期螺柱焊分析系统能实时显示焊接电流和电压波形,提取焊接参数特征值,判断电弧的稳定性,熔深计算值与实测值相吻合,在线检测结论与外观目检、宏观检测和扭矩测试的结论一致。系统收集的原始数据可用于分析引起质量问题的具体原因。 相似文献
98.
化学反应失控的紧急泄放 总被引:2,自引:0,他引:2
介绍了60 年代以来化学反应失控紧急泄放的研究状况,着重从研究方法、设计模型和实验方法等方面,对现有研究成果进行了评述。 相似文献
99.
College students estimated the weight of adult women from either photographs or a live presentation by a set of models and estimated the calories in 1 of 2 actual meals. The 2 meals had the same items, but 1 had larger portion sizes than the other. The results suggest: (a) Judgments are biased toward transforming the example in question to the size and/or properties of a “standard” unit. For estimates of body weight, students assigned weights assuming a standard height, even though height information was provided in the photographs or directly present with live models. (b) There is an inclination to focus on 1 aspect or dimension of the stimulus (e.g., for female figures, their width, for meals the identity of the components as opposed to their size) and either devalue or completely ignore another parameter critical for accurate judgment (height, for the case of body weight estimations). That is, students defaulted to a normative unit size and thus treated the stimulus as a representative, categorical, and unvarying example, and focused on only 1 dimension (univariate bias) in making judgments. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
100.
Hindsight bias has been shown to be a pervasive and potentially harmful decision-making bias. A review of 4 competing cognitive reconstruction theories of hindsight bias revealed conflicting predictions about the role and effect of expectation or surprise in retrospective judgment formation. Two experiments tested these predictions examining the effects of manipulating the information presented in a text-based scenario and its congruency with the given outcome on surprise, hindsight bias, and recall. The results of Experiment 1 revealed evidence of hindsight bias after exposure to incongruent and ambivalent outcomes but not after exposure to congruent outcomes. Experiment 2 replicated the hindsight bias results and found that the ratio of outcome consistent information recalled was higher than expected in the incongruent and ambivalent conditions but equaled the ratio presented to participants in the congruent condition. The results were interpreted as supporting the general predictions of sense-making models of the hindsight bias. A refined version of this model is discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献