全文获取类型
收费全文 | 885篇 |
免费 | 53篇 |
国内免费 | 31篇 |
专业分类
化学 | 57篇 |
晶体学 | 1篇 |
力学 | 23篇 |
综合类 | 7篇 |
数学 | 701篇 |
物理学 | 180篇 |
出版年
2023年 | 7篇 |
2022年 | 12篇 |
2021年 | 20篇 |
2020年 | 22篇 |
2019年 | 16篇 |
2018年 | 18篇 |
2017年 | 16篇 |
2016年 | 23篇 |
2015年 | 15篇 |
2014年 | 39篇 |
2013年 | 69篇 |
2012年 | 24篇 |
2011年 | 37篇 |
2010年 | 44篇 |
2009年 | 42篇 |
2008年 | 67篇 |
2007年 | 48篇 |
2006年 | 35篇 |
2005年 | 38篇 |
2004年 | 28篇 |
2003年 | 38篇 |
2002年 | 31篇 |
2001年 | 24篇 |
2000年 | 28篇 |
1999年 | 25篇 |
1998年 | 20篇 |
1997年 | 14篇 |
1996年 | 17篇 |
1995年 | 9篇 |
1994年 | 15篇 |
1993年 | 10篇 |
1992年 | 10篇 |
1991年 | 7篇 |
1990年 | 3篇 |
1989年 | 8篇 |
1988年 | 9篇 |
1987年 | 8篇 |
1986年 | 4篇 |
1985年 | 10篇 |
1984年 | 12篇 |
1983年 | 7篇 |
1982年 | 12篇 |
1981年 | 6篇 |
1980年 | 4篇 |
1979年 | 2篇 |
1978年 | 4篇 |
1977年 | 2篇 |
1975年 | 2篇 |
1974年 | 3篇 |
1973年 | 4篇 |
排序方式: 共有969条查询结果,搜索用时 15 毫秒
81.
82.
John M. Myers 《Foundations of Physics》2006,36(7):1012-1035
Motivated by a recent proof of free choices in linking equations to the experiments they describe, I clarify some relations among purely mathematical entities featured in quantum mechanics (probabilities, density operators, partial traces, and operator-valued measures), thereby allowing applications of these entities to the modeling of a wider variety of physical situations. I relate conditional probabilities associated with projection-valued measures to conditional density operators identical, in some cases but not in others, to the usual reduced density operators. While a fatal obstacle precludes associating conditional density operators with general non-projective measures, tensor products of general positive operator-valued measures (POVMs) are associated with conditional density operators. This association together with the free choice of probe particles allows a postulate of state reductions to be replaced by a theorem. An application shows an equivalence between one form of quantum key distribution and another with respect to certain eavesdropping attacks. 相似文献
83.
Alexander R. Pruss 《Stochastic Processes and their Applications》1997,70(2):1547-180
Let X1, X2, … be independent identically distributed random variables. Then, Hsu and Robbins (1947) together with Erdös (1949, 1950) have proved that ,,
if and only if E[X21] < ∞ and E[X1] = 0. We prove that there are absolute constants C1, C2 (0, ∞) such that if X1, X2, … are independent identically distributed mean zero random variables, then
c1λ−2 E[X12·1{|X1|λ}]S(λ)C2λ−2 E[X12·1{|X1|λ}]
for every λ > 0. 相似文献
84.
Emine Sarigllü 《商业与工业应用随机模型》1994,10(1):27-46
Prediction of customer choice behaviour has been a big challenge for marketing researchers. They have adopted various models to represent customers purchase patterns. Some researchers considered simple zero–order models. Others proposed higher–order models to represent explicitly customers tendency to seek [variety] or [reinforcement] as they make repetitive choices. Nevertheless, the question [Which model has the highest probability of representing some future data?] still prevails. The objective of this paper is to address this question. We assess the predictive effectiveness of the well–known customer choice models. In particular, we compare the predictive ability of the [dynamic attribute satiation] (DAS) model due to McAlister (Journal of Consumer Research, 91, pp. 141–150, 1982) with that of the well–known stochastic variety seeking and reinforcement behaviour models. We found that the stochastic [beta binomial] model has the best predictive effectiveness on both simulated and real purchase data. Using simulations, we also assessed the effectiveness of the stochastic models in representing various complex choice processes generated by the DAS. The beta binomial model mimicked the DAS processes the best. In this research we also propose, for the first time, a stochastic choice rule for the DAS model. 相似文献
85.
Exact L
2 Small Balls of Gaussian Processes 总被引:3,自引:3,他引:0
We prove a comparison theorem extending Li(6) and develop a complex-analytic approach to treat L
2 small ball probabilities of Gaussian processes. We demonstrate the techniques for the m-times integrated Brownian motions and in examples where one can not apply Li comparison theorem. 相似文献
86.
87.
88.
Clayton Keith Frey Barbara Bruhns 《Nonlinear dynamics, psychology, and life sciences》1997,1(3):173-180
Successive tests of subjects' performance in reaction time tasks were treated as time series and submitted to spectrum analysis. Rather than revealing the white noise expected by the view that variability is due to random error (equivalent power across frequency), the power spectra revealed colored noise. The slopes of the power spectra did not vary much for tasks differing in memory requirements. Spectrum analysis of time series from the logistic map also showed colored noise in regions on the edge of chaos, showing that the presence of colored noise in cognitive data need not oblige a theoretical account based on a complex, high-dimensional, system. 相似文献
89.
This paper assesses optimal life cycle consumption and portfolio allocations when households have access to Guaranteed Minimum Withdrawal Benefit (GMWB) variable annuities over their adult lifetimes. Our contribution is to evaluate demand for these products which provide access to equity investments with money-back guarantees, longevity risk hedging, and partially-refundable premiums, in a realistic world with uncertain labor and capital market income as well as mortality risk. Others have predicted that consumers will only purchase such annuities late in life, but we show that they will optimally purchase GMWBs prior to retirement, consistent with their recent rapid uptick in sales. Additionally, many individuals optimally adjust their portfolios and consumption streams along the way by taking cash withdrawals from the products. These products can substantially enhance consumption, by up to 10% for those who experience highly unfavorable experiences in the stock market. 相似文献
90.
Aurel Sp?taru 《Statistics & probability letters》2011,81(10):1547-1551
Let X,X1,X2,… be i.i.d. random variables, and set Sn=X1+?+Xn. We prove that for three important distributions of X, namely normal, exponential and geometric, series of the type ∑n≥1anP(|Sn|≥xbn) or ∑n≥1anP(Sn≥xbn) behave like their first term as x→∞. 相似文献