全文获取类型
收费全文 | 388篇 |
免费 | 43篇 |
国内免费 | 16篇 |
专业分类
电工技术 | 15篇 |
综合类 | 10篇 |
化学工业 | 70篇 |
金属工艺 | 61篇 |
机械仪表 | 48篇 |
建筑科学 | 4篇 |
矿业工程 | 5篇 |
能源动力 | 21篇 |
轻工业 | 16篇 |
水利工程 | 3篇 |
石油天然气 | 33篇 |
武器工业 | 5篇 |
无线电 | 42篇 |
一般工业技术 | 51篇 |
冶金工业 | 11篇 |
原子能技术 | 16篇 |
自动化技术 | 36篇 |
出版年
2024年 | 1篇 |
2023年 | 7篇 |
2022年 | 24篇 |
2021年 | 22篇 |
2020年 | 21篇 |
2019年 | 7篇 |
2018年 | 10篇 |
2017年 | 14篇 |
2016年 | 10篇 |
2015年 | 15篇 |
2014年 | 14篇 |
2013年 | 17篇 |
2012年 | 20篇 |
2011年 | 15篇 |
2010年 | 19篇 |
2009年 | 14篇 |
2008年 | 20篇 |
2007年 | 19篇 |
2006年 | 21篇 |
2005年 | 15篇 |
2004年 | 17篇 |
2003年 | 5篇 |
2002年 | 9篇 |
2001年 | 13篇 |
2000年 | 17篇 |
1999年 | 17篇 |
1998年 | 10篇 |
1997年 | 5篇 |
1996年 | 14篇 |
1995年 | 5篇 |
1994年 | 10篇 |
1993年 | 6篇 |
1992年 | 1篇 |
1991年 | 4篇 |
1990年 | 2篇 |
1989年 | 2篇 |
1986年 | 1篇 |
1985年 | 3篇 |
1984年 | 1篇 |
排序方式: 共有447条查询结果,搜索用时 78 毫秒
21.
22.
A numerical integral method that efficiently provides the solution of the point kinetics equations by using the better basis function (BBF) for the approximation of the neutron density in one time step integrations is described and investigated. The approach is based on an exact analytic integration of the neutron density equation, where the stiffness of the equations is overcome by the fully implicit formulation. The procedure is tested by using a variety of reactivity functions, including step reactivity insertion, ramp input and oscillatory reactivity changes. The solution of the better basis function method is compared to other analytical and numerical solutions of the point reactor kinetics equations. The results show that selecting a better basis function can improve the efficiency and accuracy of this integral method. The better basis function method can be used in real time forecasting for power reactors in order to prevent reactivity accidents. 相似文献
23.
基于电化学原理发展起来的电化学测试技术,如极化曲线分析法,交流阻抗分析法,电化学噪声分析法和Kelvin探针技术等,是研究腐蚀的重要手段,近些年有了很大的进展。掌握这些技术的原理及应用领域的进步,将有助于对腐蚀与防护技术的深入研究和开发。 相似文献
24.
25.
The irradiation damages in the electron beam lithography(EBL)to Al-gate MOS capacitors in the ranges of 10—30keV and 10~(-6)—10~(-3)C·cm~(-2) and the effects of annealing on damages at low temperature(<500℃)are given.The research on damages caused by high electron energy(30keV) and ultra-high dosages(10~(-4)—10~(-3) C·cm~(-2))is important and useful to the EBL.The resolution can be improved by high electron energy.Both the EBL with vapor-development and without development are all operated at ultra-high dosages.After irradiations,the concentrations of inter- face states can increase by about one to two orders of magnitude and the flat-band voltages by about a few to more than ten volts.Under constant exposure dosages,the fiat-band voltages are independent of the changes of electron energies in certain energy ranges.Under constant electron energies the concentrations of interface states are independent of the changes of exposure dosages in certain dosage ranges.After annealing,the flat-band voltages can recover the values before the irradiations for energies and dosages in the ranges of 10—30keV and 1×10~(-6)—6×10~(-3)C·cm~(-2) respectively.The interface state concentrations due to the damages of ultra dosages can not be removed completely. 相似文献
26.
In this article, we first propose a novel Trefftz energy method (TEM) for the numerical analysis of heat transfer in arbitrary plane domains. The TEM introduces the Trefftz energy bases in the complete linear space to approximate the numerical solution of the mixed boundary value problem in the heat transfer over an arbitrary plane domain. The Trefftz energy bases not only satisfy the Laplace equation but also preserve the energy, whose performance is better than the original Trefftz bases. Three benchmark numerical examples are tested to demonstrate the efficiency and accuracy of the proposed TEM. Although the multiple-scale Trefftz method can treat these problems with high accuracy, the TEM can further raise the accuracy with one order. Therefore, the present scheme is a competitive alternative to existing methods for solving heat transfer problems in arbitrary plane domains. 相似文献
27.
研究了两种线性与非线性传热条件下的不可逆卡诺循环。循环中不可逆传热服从吸热Q1∝T^-m,放热Q2∝T^m,其中m=-1,1。而工质内部一切因非平衡引起的不可塑性,根据实际工程所采用的方法以内效率ηi来表示。由此求得循环的功率P与效率η的优化关系,并讨论了这一关系的一些应用,所得结果可为实际热机设计提供更丰富的理论依据。 相似文献
28.
Julia Dittrich Susen Becker Max Hecht Uta Ceglarek 《Proteomics. Clinical applications》2015,9(1-2):5-16
The simultaneous quantification of protein concentrations via proteotypic peptides in human blood by liquid chromatography coupled to quadrupole MS/MS is an important field of bioanalytical research with a high potential for routine diagnostic applications. This review summarizes currently available sample preparation procedures and trends for absolute protein quantification in blood using LC-MS/MS. It discusses approaches of transferring established qualitative protocols to a quantitative analysis regarding their reliability and reproducibility. Techniques used to enhance method sensitivity such as the depletion of high-abundant proteins or the immunoaffinity enrichment of proteins and peptides are described. Furthermore, workflows for (i) protein denaturation, (ii) disulfide bridge reduction and (iii) thiol alkylation as well as (iv) enzymatic digestion for absolute protein quantification are presented. The main focus is on the tryptic digestion as a bottleneck of protein quantification via proteotypic peptides. Conclusively, requirements for a high-throughput application are discussed. 相似文献
29.
30.
水力射孔射流压裂工艺在长庆油田的应用 总被引:7,自引:1,他引:6
水力射孔射流压裂集水力喷砂射孔和射流加砂压裂于一体,是一项重大革新型的增产工艺。该工艺采用水力喷射专用工具,首先依靠高速射流作用实现套管射孔,并在射流状态下直接进行压裂作业,既可用于水平井多段压裂改造,也可用于直井单段或多段压裂改造。现场应用表明,对于水平井,该工艺可缩短施工周期、降低施工费用、提高作业安全性;对于直井,除具有传统压裂的作用之外,可在近井地带产生高导流缝穴,有利于增产和稳产。该工艺具有施工高效性、经济性、安全性以及明显的增产能力,对于低渗透油气田的开发意义较大。 相似文献