全文获取类型
收费全文 | 5233篇 |
免费 | 252篇 |
出版年
2023年 | 39篇 |
2020年 | 109篇 |
2019年 | 111篇 |
2018年 | 188篇 |
2017年 | 193篇 |
2016年 | 217篇 |
2015年 | 138篇 |
2014年 | 138篇 |
2013年 | 1523篇 |
2012年 | 167篇 |
2011年 | 196篇 |
2010年 | 178篇 |
2009年 | 147篇 |
2008年 | 119篇 |
2007年 | 113篇 |
2006年 | 123篇 |
2005年 | 81篇 |
2004年 | 59篇 |
2003年 | 65篇 |
2002年 | 71篇 |
2001年 | 76篇 |
2000年 | 67篇 |
1999年 | 81篇 |
1998年 | 62篇 |
1997年 | 44篇 |
1996年 | 36篇 |
1995年 | 49篇 |
1994年 | 35篇 |
1993年 | 50篇 |
1992年 | 33篇 |
1991年 | 43篇 |
1990年 | 47篇 |
1989年 | 42篇 |
1988年 | 33篇 |
1987年 | 44篇 |
1986年 | 47篇 |
1985年 | 47篇 |
1984年 | 52篇 |
1983年 | 47篇 |
1982年 | 41篇 |
1981年 | 47篇 |
1980年 | 42篇 |
1979年 | 39篇 |
1978年 | 36篇 |
1977年 | 36篇 |
1975年 | 27篇 |
1974年 | 27篇 |
1973年 | 29篇 |
1972年 | 29篇 |
1970年 | 27篇 |
排序方式: 共有5485条查询结果,搜索用时 15 毫秒
21.
ABSTRACT. The dynamic relationship between sectoral value added and regional economic growth is analyzed using a stochastic intersectoral model estimated by ordinary least squares and linear systems techniques. A state-space portion of the model identifies the time element of sedoral value added. Dynamic multipliers, tracing the temporal path of regional growth, are calculated for the state of Georgia over the period 1963–1986. This application shows that the impacts of sectoral shocks can follow cyclical as well as monotonic patterns and that the direction and magnitude of the impact may change over time. 相似文献
22.
Spatial compactness has been proposed as a suitable criterion for assessing whether electoral boundaries reflect partisan interests. Although several different measures of spatial compactness have been developed, only limited efforts have been made to compare and evaluate them in the context of electoral redistricting. This paper assesses alternative spatial compactness measures and applies conceptually appealing measures to the provincial ridings proposed by British Columbia's Royal Commission on Electoral Boundaries (1988). 相似文献
23.
Three rare Himyaritic coins found in the territory of the ancient Hadramawt kingdom are published for the first time. Two of the coins bear the name of the king,'Amdan Bayyin, while the third has the name of Tha'ran Ya'ub. 相似文献
24.
25.
26.
An attempt has been made to relate steatite artifacts to the source of rock from which they were manufactured, using the distribution patterns of rare earth elements. Radiochemical- and instrumental-neutron activation analyses of Shetland steatites suggest that the use of rare earth elements in artifact provenancing may be unreliable. Concentrations of rare earth elements in many Shetland steatites are too low to be measured reliably by a cost effective method. The relative importance of primary igneous and secondary metasomatic processes in controlling steatite rare earth element geochemistry is discussed and geological arguments against the existence of unique rare earth ‘fingerprints’ for steatite are presented. 相似文献
27.
28.
29.
'Ali Perwāz SR 《Indian journal of history of science》1986,21(4):297-314
30.