全文获取类型
收费全文 | 42162篇 |
免费 | 2512篇 |
国内免费 | 45篇 |
专业分类
电工技术 | 346篇 |
综合类 | 33篇 |
化学工业 | 8936篇 |
金属工艺 | 818篇 |
机械仪表 | 855篇 |
建筑科学 | 1285篇 |
矿业工程 | 88篇 |
能源动力 | 969篇 |
轻工业 | 6916篇 |
水利工程 | 394篇 |
石油天然气 | 151篇 |
武器工业 | 6篇 |
无线电 | 1703篇 |
一般工业技术 | 6993篇 |
冶金工业 | 8997篇 |
原子能技术 | 189篇 |
自动化技术 | 6040篇 |
出版年
2024年 | 69篇 |
2023年 | 335篇 |
2022年 | 600篇 |
2021年 | 1168篇 |
2020年 | 837篇 |
2019年 | 992篇 |
2018年 | 1664篇 |
2017年 | 1607篇 |
2016年 | 1687篇 |
2015年 | 1262篇 |
2014年 | 1559篇 |
2013年 | 3084篇 |
2012年 | 2461篇 |
2011年 | 2445篇 |
2010年 | 1915篇 |
2009年 | 1782篇 |
2008年 | 1700篇 |
2007年 | 1581篇 |
2006年 | 1125篇 |
2005年 | 976篇 |
2004年 | 870篇 |
2003年 | 770篇 |
2002年 | 753篇 |
2001年 | 569篇 |
2000年 | 539篇 |
1999年 | 568篇 |
1998年 | 2796篇 |
1997年 | 1895篇 |
1996年 | 1219篇 |
1995年 | 734篇 |
1994年 | 571篇 |
1993年 | 646篇 |
1992年 | 243篇 |
1991年 | 250篇 |
1990年 | 192篇 |
1989年 | 189篇 |
1988年 | 190篇 |
1987年 | 167篇 |
1986年 | 151篇 |
1985年 | 174篇 |
1984年 | 148篇 |
1983年 | 120篇 |
1982年 | 156篇 |
1981年 | 177篇 |
1980年 | 178篇 |
1979年 | 90篇 |
1978年 | 96篇 |
1977年 | 308篇 |
1976年 | 663篇 |
1973年 | 79篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
141.
This paper reports the results of current fundamental research at the Department of Process Engineering, University of Miskolc on the processing of clean coal from Mecsek bituminous coal, Southern Hungary. The theoretical possibility of the separation of different petrographic components was proven experimentally and their liberation degree was determined based on the petrographic composition, flotation kinetic study of isolated components (groups of components), scanning electron microscopy and microprobe analyses. The mill with stirred ball media was chosen for the ultra-fine liberation of the coal components. It was revealed that along with the liberation of coal components, their surface oxidation and spontaneous agglomeration, entrapping the mineral impurities take place in ultra-fine grinding. This paper discusses the interfacial phenomena occurring in the ultra-fine grinding process and their influence on the flotation. The concept for the advanced preparation of clean coal was developed, tested and proved. The main steps of this concept are the ultra-fine liberation in the stirred-media mill, the de-agglomeration of flocs spontaneously formed during the ultra-fine grinding and the induced (hydrophobic) flocculation with the following two-step flotation in a flotation column. 相似文献
142.
Tams Insperger Gbor Stpn 《International journal for numerical methods in engineering》2004,61(1):117-141
An updated version of the semi‐discretization method is presented for periodic systems with a single discrete time delay. The delayed term is approximated as a weighted sum of two neighbouring discrete delayed state values and the transition matrix over a single period is determined. Stability charts are constructed for the damped and delayed Mathieu equation for different time‐period/time‐delay ratios. The convergence of the method is investigated by examples. Stability charts are constructed for 1 and 2 degree of freedom milling models. The codes of the algorithm are also attached in the appendix. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
143.
144.
145.
146.
This paper presents an analysis of the data collected in the ambient vibration test of the International Guadiana cable-stayed Bridge, which links Portugal and Spain, based on different output-only identification techniques: peak-picking, frequency domain decomposition, covariance-driven stochastic subspace identification, and data-driven stochastic subspace identification. The purpose of the analysis is to compare the performance of the four techniques and evaluate their efficiency in dealing with specific challenges involved in the modal identification of the tested cable-stayed bridge, namely the existence of closely spaced modes, the perturbation produced by the local vibration of stay-cables, and the variation of modal damping coefficients with wind velocity. The identified natural frequencies and mode shapes are compared with the corresponding modal parameters provided by a previously developed numerical model. Additionally, the variability of some modal damping coefficients is related with the variation of the wind characteristics and associated with a component of aerodynamic damping. 相似文献
147.
Mariana Ušáková Jozef Lukáč Rastislav Dosoudil Vladimír Jančárik Anna Grusková Elemír Ušák Jozef Sláma Jan Šubrt 《Journal of Materials Science: Materials in Electronics》2007,18(12):1183-1189
The paper is devoted to the preparation of NiZn ferrite with small substitutions of copper by means of ceramic technology.
The influence of small Cu substitution on the microstructural and magnetic properties of NiZn ferrites have been analysed
by means of various experimental methods and interpreted from the point of view of preparation technology optimisation and
possible applications of such materials. A strong correlation between the substituent content and resulting properties has
been observed, thus allowing preparation of material with the properties tailored for any particular application. 相似文献
148.
Here we are presenting the case of a 70-years-old woman who has hepatic cirrhosis anti-HCV and insulin-dependent diabetes mellitus, without relevant epidemiologic ascendants or previous transfusions and HBV, HIV negatives. On admission to our hospital she showed signs of autoimmune hemolytic anaemia (AHA) which was confirmed by positive direct Coombs test and an improvement in blood test after corticoid treatment. Having discarded other possible causes such as drugs infectious diseases or essential mixed cryoglobulinemia (CME), we put forward the possible association between AHA and infection by HCV, where AHA was an extrahepatic immunological manifestation of HCV. This fact has never been brought to light in previous medical literature. 相似文献
149.
The authors describe the illness of a Czech soldier who while serving in the UNPROFOR forces in an area with the endemic occurrence of hantaviruses became infected with this agent and developed haemorrhagic fever with renal syndrome. The severe clinical course which called for seven haemodialyzation procedures led to the patient's recovery. The authors describe the course of the disease and epidemiological circumstances. 相似文献
150.