全文获取类型
收费全文 | 83705篇 |
免费 | 690篇 |
国内免费 | 427篇 |
专业分类
化学 | 28527篇 |
晶体学 | 829篇 |
力学 | 6825篇 |
数学 | 32499篇 |
物理学 | 16142篇 |
出版年
2022年 | 66篇 |
2021年 | 132篇 |
2020年 | 101篇 |
2019年 | 114篇 |
2018年 | 10509篇 |
2017年 | 10324篇 |
2016年 | 6244篇 |
2015年 | 1028篇 |
2014年 | 512篇 |
2013年 | 687篇 |
2012年 | 4182篇 |
2011年 | 10960篇 |
2010年 | 5919篇 |
2009年 | 6264篇 |
2008年 | 6959篇 |
2007年 | 9068篇 |
2006年 | 562篇 |
2005年 | 1592篇 |
2004年 | 1803篇 |
2003年 | 2202篇 |
2002年 | 1221篇 |
2001年 | 352篇 |
2000年 | 388篇 |
1999年 | 225篇 |
1998年 | 244篇 |
1997年 | 194篇 |
1996年 | 256篇 |
1995年 | 166篇 |
1994年 | 124篇 |
1993年 | 125篇 |
1992年 | 85篇 |
1991年 | 88篇 |
1990年 | 87篇 |
1989年 | 96篇 |
1988年 | 88篇 |
1987年 | 80篇 |
1986年 | 76篇 |
1985年 | 88篇 |
1984年 | 71篇 |
1983年 | 58篇 |
1982年 | 67篇 |
1981年 | 64篇 |
1980年 | 66篇 |
1979年 | 73篇 |
1978年 | 52篇 |
1977年 | 42篇 |
1973年 | 52篇 |
1914年 | 46篇 |
1912年 | 41篇 |
1909年 | 41篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
Zenon Moszner 《Aequationes Mathematicae》2018,92(4):617-625
We give the form of the output function in Ginsburg’s machine in which the input and output dictionaries are abelian groups and the transition function is of a special form. 相似文献
22.
23.
24.
25.
26.
The structure, chemical composition, and magnetic properties of electrochemically deposited nanocrystalline Co-Ni-Fe films
were investigated using a number of techniques. A high saturation magnetic induction up to B
s
= 21 kG was attained. An enhancement of the saturation magnetization compared to the ideal anticipated one was revealed,
which correlated with the nonlinear behavior of the structural phase composition and lattice parameters with the change of
the composition.
The text was submitted by the authors in English. 相似文献
27.
28.
Laser welding is one of the most precise welding processes in joining sheet metals. In laser welding, performing real time evaluation of the welding quality is very important to enhance the efficiency of the welding process. In this study, the plasma and spatter, which are generated during laser welding, are measured using UV and IR photodiodes. The factors that influence weld quality are classified into five categories; optimal heat input, slightly low heat input, low heat input, partial joining due to gap mismatch, and nozzle deviation. The data number deviated from reference signals and their standard deviations were also considered to evaluate the qualities. A system was also formulated to perform real time evaluations of the weld quality using a fuzzy multi-feature pattern recognition with the measured signals. 相似文献
29.
A forecasting model is developed for the number of daily applications for loans at a financial services telephone call centre. The purpose of the forecasts and the associated prediction intervals is to provide effective staffing policies within the call centre. The model building process is constrained by the availability of only 2 years and 7 months of data. The distinctive feature of the data is that demand is driven in the main by advertising. The analysis given focuses on applications stimulated by press advertising. Unlike previous analyses of broadly similar data, where ARIMA models were used, a model with a dynamic level, multiplicative calendar effects and a multiplicative advertising response is developed and shown to be effective. 相似文献
30.
Chee Sing Yap 《The Journal of the Operational Research Society》1989,40(7):649-658
This paper describes three case studies which investigated issues relating to the implementation and management of advanced information technology. The benefits derived from information technology were found to vary from one organization to another. These studies provide further evidence to support earlier research findings that senior management has an important role to play in the effective exploitation of information technology, and that the investment approach taken by an organization has a significant effect on the development of computer-based information systems. The effectiveness of a system depends not only on applying the appropriate technology, but also on how successfully technical and behavioural issues are resolved. 相似文献