全文获取类型
收费全文 | 211311篇 |
免费 | 1764篇 |
国内免费 | 500篇 |
专业分类
化学 | 110840篇 |
晶体学 | 3431篇 |
力学 | 10471篇 |
综合类 | 10篇 |
数学 | 23167篇 |
物理学 | 65656篇 |
出版年
2021年 | 2072篇 |
2020年 | 2146篇 |
2019年 | 2702篇 |
2018年 | 3755篇 |
2017年 | 3737篇 |
2016年 | 5021篇 |
2015年 | 2518篇 |
2014年 | 4505篇 |
2013年 | 9066篇 |
2012年 | 7347篇 |
2011年 | 8695篇 |
2010年 | 6750篇 |
2009年 | 6868篇 |
2008年 | 8124篇 |
2007年 | 8161篇 |
2006年 | 7291篇 |
2005年 | 6395篇 |
2004年 | 6083篇 |
2003年 | 5540篇 |
2002年 | 5496篇 |
2001年 | 5737篇 |
2000年 | 4222篇 |
1999年 | 3215篇 |
1998年 | 2776篇 |
1997年 | 2860篇 |
1996年 | 2650篇 |
1995年 | 2290篇 |
1994年 | 2401篇 |
1993年 | 2308篇 |
1992年 | 2593篇 |
1991年 | 2699篇 |
1990年 | 2632篇 |
1989年 | 2665篇 |
1988年 | 2589篇 |
1987年 | 2606篇 |
1986年 | 2483篇 |
1985年 | 3137篇 |
1984年 | 3204篇 |
1983年 | 2663篇 |
1982年 | 2652篇 |
1981年 | 2618篇 |
1980年 | 2425篇 |
1979年 | 2770篇 |
1978年 | 2755篇 |
1977年 | 2928篇 |
1976年 | 2930篇 |
1975年 | 2715篇 |
1974年 | 2632篇 |
1973年 | 2767篇 |
1972年 | 2103篇 |
排序方式: 共有10000条查询结果,搜索用时 187 毫秒
191.
192.
193.
194.
E. N. Yurchenko G. E. Kramareva N. G. Zubritskaya T. P. Gaidei 《Reaction Kinetics and Catalysis Letters》1995,55(2):425-432
In the Russian Scientific Center Applied Chemistry catalysts have been developed for the gas-phase fluorination of organics, including chlorine-containing substances, hydrogenation and reductive amination of organic substances, decomposition of liquid substances to gases, complete oxidation and reduction, suitable for environment at protection. 相似文献
195.
We investigate the replica symmetry breaking (RSB) in a neighborhood of the instability point of the replica-symmetric solution in the axial quadrupolar glass model. We show that the solution with the first-stage RSB is stable against the subsequent RSB. Although there is no reflection symmetry, the first-stage RSB solution continuously bifurcates from the replica-symmetric one. This implies that our model does not belong to either of the two classes into which spin glasses are usually divided. 相似文献
196.
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
197.
198.
199.
200.
Let V be a hypersurface with an isolated singularity at the origin in ? n+1. It is a natural question to ask when V is defined by weighted homogeneous polynomial or homogeneous polynomial up to biholomorphic change of coordinates. In 1971, a beautiful theorem of Saito gives a necessary and sufficient condition for V to be defined by a weighted homogeneous polynomial. For a two-dimensional isolated hypersurface signularity V, Xu and Yau found a coordinate free characterization for V to be defined by a homogeneous polynomial. Recently Lin and Yau gave necessary and sufficient conditions for a 3-dimensional isolated hypersurface singularity with geometric genus bigger than zero to be defined by a homogeneous polynomial. The purpose of this paper is to prove that Lin-Yau’s theorem remains true for singularities with geometric genus equal to zero. 相似文献