全文获取类型
收费全文 | 1500篇 |
免费 | 155篇 |
国内免费 | 63篇 |
专业分类
化学 | 43篇 |
晶体学 | 1篇 |
力学 | 551篇 |
综合类 | 43篇 |
数学 | 814篇 |
物理学 | 266篇 |
出版年
2024年 | 1篇 |
2023年 | 21篇 |
2022年 | 33篇 |
2021年 | 54篇 |
2020年 | 38篇 |
2019年 | 30篇 |
2018年 | 33篇 |
2017年 | 36篇 |
2016年 | 53篇 |
2015年 | 41篇 |
2014年 | 71篇 |
2013年 | 86篇 |
2012年 | 53篇 |
2011年 | 66篇 |
2010年 | 61篇 |
2009年 | 68篇 |
2008年 | 66篇 |
2007年 | 89篇 |
2006年 | 71篇 |
2005年 | 97篇 |
2004年 | 61篇 |
2003年 | 65篇 |
2002年 | 66篇 |
2001年 | 57篇 |
2000年 | 44篇 |
1999年 | 49篇 |
1998年 | 35篇 |
1997年 | 41篇 |
1996年 | 46篇 |
1995年 | 42篇 |
1994年 | 25篇 |
1993年 | 16篇 |
1992年 | 14篇 |
1991年 | 12篇 |
1990年 | 9篇 |
1989年 | 3篇 |
1988年 | 8篇 |
1987年 | 10篇 |
1986年 | 3篇 |
1985年 | 11篇 |
1984年 | 15篇 |
1983年 | 2篇 |
1982年 | 3篇 |
1981年 | 3篇 |
1980年 | 1篇 |
1979年 | 2篇 |
1978年 | 3篇 |
1977年 | 1篇 |
1976年 | 2篇 |
1973年 | 1篇 |
排序方式: 共有1718条查询结果,搜索用时 187 毫秒
21.
22.
在多项选择题测验分数等于真实分数和猜测分数之和的假设模型下,本文得到了一个多项选择题测验信度的理论公式,并由此给出了测验信度的估计方法。最后,通过两个例子,说明了本文提出的方法在测验信度分析中的应用,并将这种方法与教育测量中常用的库德——理查逊方法(Kuder-Richardson)进行了比较 相似文献
23.
无失效数据的Bayes和多层Bayes分析 总被引:3,自引:0,他引:3
本文推广了文献[6]的结果,对指数分布无失效数据的失效率,给出了Bayes估计、Bayes置信上限以及多层Bayes估计,从而可以得到无失效数据可靠度的估计,最后,结合实际问题进行了计算。 相似文献
24.
本文在Menser概率赋范空间中引入了(Φ,Δ)型概率收缩的概念,研究了Menger概率赋范空间中具有这类概率收缩的非线性算子方程的解的存在性与唯一性.发展和改进了引文[1]、[4~8]的相应结果. 相似文献
25.
We exhibit a probabilistic algorithm which computes a rational point of an absolutely irreducible variety over a finite field defined by a reduced regular sequence. Its time-space complexity is roughly quadratic in the logarithm of the cardinality of the field and a geometric invariant of the input system. This invariant, called the degree, is bounded by the Bézout number of the system. Our algorithm works for fields of any characteristic, but requires the cardinality of the field to be greater than a quantity which is roughly the fourth power of the degree of the input variety.
26.
27.
Reliability bounds in DFRA class with known mean and variance 总被引:1,自引:0,他引:1
RELIABILITYBOUNDSINDFRACLASSWITHKNOWNMEAN AND VARIANCECHENGKAN(程侃)(InstituteofAppliedMathematics,theChineseAcademyofScience,B... 相似文献
28.
Assume that the probability density function for the lifetime of a newly designed product has the form: [H(t)/Q()] exp{–H(t)/Q()}. The Exponential(), Rayleigh, WeibullW(, ) and Pareto pdf's are special cases.Q() will be assumed to have an inverse Gamma prior. Assume thatm independent products are to be tested with replacement. A Bayesian Sequential Reliability Demonstration Testing plan is used to eigher accept the product and start formal production, or reject the product for reengineering. The test criterion is the intersection of two goals, a minimal goal to begin production and a mature product goal. The exact values of various risks and the distribution of total number of failures are evaluated. Based on a result about a Poisson process, the expected stopping time for the exponential failure time is also found. Included in these risks and expected stopping times are frequentist versions, thereof, so that the results also provide frequentist answers for a class of interesting stopping rules.This research was supported by NSF grants DMS-8703620 and DMS-8923071, and forms part of the Ph.D. Thesis of the first author, the development of which was supported in part by a David Ross grant at Purdue University. The authors thank the editors and a referee for insightful comments and suggestions. 相似文献
29.
Using a probabilistic approach, the deterministic and the stochastic parallel dynamics of aQ-Ising neural network are studied at finiteQ and in the limitQ. Exact evolution equations are presented for the first time-step. These formulas constitute recursion relations for the parallel dynamics of the extremely diluted asymmetric versions of these networks. An explicit analysis of the retrieval properties is carried out in terms of the gain parameter, the loading capacity, and the temperature. The results for theQ network are compared with those for theQ=3 andQ=4 models. Possible chaotic microscopic behavior is studied using the time evolution of the distance between two network configurations. For arbitrary finiteQ the retrieval regime is always chaotic. In the limitQ the network exhibits a dynamical transition toward chaos. 相似文献
30.
Karol Jankowski Danuta Rutkowska Andrzej Rutkowski 《Theoretical chemistry accounts》1978,48(2):119-125
It is shown that the Galerkin-Petrov method if applied in a controlled way yields reliable results for excited states of the
same symmetry classifications as the ground state. Computations are performed for the 21
S and 31
S states of He. The problem of optimizing nonlinear parameters of the basis functions by means of the GP method is discussed.
A special optimization scheme is suggested and numerically illustrated for someS states of He. 相似文献