全文获取类型
收费全文 | 31608篇 |
免费 | 3858篇 |
国内免费 | 2216篇 |
专业分类
化学 | 7474篇 |
晶体学 | 108篇 |
力学 | 4992篇 |
综合类 | 512篇 |
数学 | 11839篇 |
物理学 | 12757篇 |
出版年
2024年 | 57篇 |
2023年 | 322篇 |
2022年 | 901篇 |
2021年 | 960篇 |
2020年 | 1150篇 |
2019年 | 984篇 |
2018年 | 901篇 |
2017年 | 1176篇 |
2016年 | 1411篇 |
2015年 | 1055篇 |
2014年 | 1642篇 |
2013年 | 2382篇 |
2012年 | 1734篇 |
2011年 | 2044篇 |
2010年 | 1725篇 |
2009年 | 2068篇 |
2008年 | 1901篇 |
2007年 | 1892篇 |
2006年 | 1591篇 |
2005年 | 1426篇 |
2004年 | 1337篇 |
2003年 | 1110篇 |
2002年 | 1066篇 |
2001年 | 859篇 |
2000年 | 798篇 |
1999年 | 701篇 |
1998年 | 631篇 |
1997年 | 468篇 |
1996年 | 401篇 |
1995年 | 387篇 |
1994年 | 367篇 |
1993年 | 294篇 |
1992年 | 268篇 |
1991年 | 207篇 |
1990年 | 180篇 |
1989年 | 133篇 |
1988年 | 129篇 |
1987年 | 140篇 |
1986年 | 143篇 |
1985年 | 132篇 |
1984年 | 140篇 |
1983年 | 76篇 |
1982年 | 100篇 |
1981年 | 67篇 |
1980年 | 29篇 |
1979年 | 48篇 |
1978年 | 32篇 |
1977年 | 30篇 |
1976年 | 15篇 |
1973年 | 22篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
91.
Zhaohui Wang 《Thermochimica Acta》2004,414(1):31-33
Microcalorimetric measurements of excess molar enthalpies, at 298.15 K, are reported for the four binary systems formed by mixing 1-hexene with the cycloalkanes: cyclohexane and methylcyclohexane, and with the aromatic hydrocarcons: benzene and toluene. Smooth Redlich-Kister representations of the results are presented. It was found that the Liebermann-Fried model also provided good representations of the results. 相似文献
92.
93.
Most of the methods used in the ARCH literature for selecting the appropriate model are based on evaluating the ability of the models to describe the data. An alternative model selection approach is examined based on the evaluation of the predictability of the models in terms of standardized prediction errors. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
94.
We present the procedure of exactly solving the Izergin–Korepin model with open boundary conditions by using the algebraic Bethe ansatz, which include constructing the multi-particle state and achieving the eigenvalue of the transfer matrix and corresponding Bethe equations. We give a proof about our conclusions on the multi-particle state based on an assumption. When the model is Uq(su(2)) quantum invariant, our results agree with that obtained by analytic Bethe ansatz method. 相似文献
95.
本文利用我国上市公司1997至2002年的有关财务数据,建立了我国上市公司资本成本面板数据模型,运用该模型分析了我国上市公司资本成本与财务杠杆、企业规模的关系.结果表明,财务杠杆的提升、企业规模的扩大将使资本成本下降.该结论对我国上市公司优化资本结构、提高企业价值具有一定的参考价值. 相似文献
96.
An Application of Branch and Cut to Open Pit Mine Scheduling 总被引:5,自引:0,他引:5
The economic viability of the modern day mine is highly dependent upon careful planning and management. Declining trends in average ore grades, increasing mining costs and environmental considerations will ensure that this situation will remain in the foreseeable future. The operation and management of a large open pit mine having a life of several years is an enormous and complex task. Though a number of optimization techniques have been successfully applied to resolve some important problems, the problem of determining an optimal production schedule over the life of the deposit is still very much unresolved. In this paper we will critically examine the techniques that are being used in the mining industry for production scheduling indicating their limitations. In addition, we present a mixed integer linear programming model for the scheduling problems along with a Branch and Cut solution strategy. Computational results for practical sized problems are discussed. 相似文献
97.
98.
本文从非线性自然观的视野。引用与分析了社会经济系统功能模型与效应模型。构建了系统和谐状态模型与和谐状态可信度模型,形象地说明了企业系统的和谐既是一个随机不确定状态。又是企业和谐力量与不和谐力量相互抗争干涉的过程。依据协同学原理提出了企业系统和谐演进的机制,表明企业系统的和谐发展是子系统和谐协同的过程。即子系统竞争合作的过程。文中所构建的模型,从理论上清晰地说明了企业系统和谐有序运行的机理,为如何构建和谐企业。提供了建设性的思考。 相似文献
99.
100.
Absorption and luminiscence measurements were performed on lead-doped KCl:KI mixed single crystals. Strong differences were found between as-grown and quenched samples. New bands were observed in the absorption spectra of unquenched samples in the spectral region between the limit positions of the A bands, corresponding to chloride or iodide lattices. The strong band at 449 nm dominates the luminescence of these samples at low temperatures. Its kinetics have a complicated form and the decay time is in the interval from ns to ms. Quenched samples have a well-known luminescence spectrum caused by octahedral lead impurity centres in KCl single crystals. The kinetics, however, also indicate mixed chlorine and iodine coordination of lead in the investigated crystals. 相似文献