全文获取类型
| 收费全文 | 3448篇 |
| 免费 | 150篇 |
| 国内免费 | 42篇 |
专业分类
| 电工技术 | 119篇 |
| 综合类 | 94篇 |
| 化学工业 | 255篇 |
| 金属工艺 | 23篇 |
| 机械仪表 | 166篇 |
| 建筑科学 | 144篇 |
| 矿业工程 | 27篇 |
| 能源动力 | 165篇 |
| 轻工业 | 30篇 |
| 水利工程 | 38篇 |
| 石油天然气 | 57篇 |
| 武器工业 | 10篇 |
| 无线电 | 165篇 |
| 一般工业技术 | 462篇 |
| 冶金工业 | 123篇 |
| 原子能技术 | 36篇 |
| 自动化技术 | 1726篇 |
出版年
| 2025年 | 4篇 |
| 2024年 | 25篇 |
| 2023年 | 54篇 |
| 2022年 | 31篇 |
| 2021年 | 44篇 |
| 2020年 | 80篇 |
| 2019年 | 71篇 |
| 2018年 | 69篇 |
| 2017年 | 96篇 |
| 2016年 | 131篇 |
| 2015年 | 133篇 |
| 2014年 | 213篇 |
| 2013年 | 226篇 |
| 2012年 | 165篇 |
| 2011年 | 275篇 |
| 2010年 | 163篇 |
| 2009年 | 241篇 |
| 2008年 | 244篇 |
| 2007年 | 214篇 |
| 2006年 | 195篇 |
| 2005年 | 168篇 |
| 2004年 | 106篇 |
| 2003年 | 87篇 |
| 2002年 | 87篇 |
| 2001年 | 67篇 |
| 2000年 | 52篇 |
| 1999年 | 51篇 |
| 1998年 | 46篇 |
| 1997年 | 52篇 |
| 1996年 | 40篇 |
| 1995年 | 26篇 |
| 1994年 | 30篇 |
| 1993年 | 12篇 |
| 1992年 | 19篇 |
| 1991年 | 21篇 |
| 1990年 | 11篇 |
| 1989年 | 9篇 |
| 1988年 | 14篇 |
| 1987年 | 13篇 |
| 1986年 | 6篇 |
| 1985年 | 9篇 |
| 1984年 | 7篇 |
| 1983年 | 3篇 |
| 1982年 | 9篇 |
| 1981年 | 9篇 |
| 1980年 | 5篇 |
| 1978年 | 3篇 |
| 1977年 | 2篇 |
| 1975年 | 1篇 |
| 1955年 | 1篇 |
排序方式： 共有3640条查询结果，搜索用时 15 毫秒
91.
In an array of threshold devices, we examine the effect of noise in improving performance of turbo code decoding. Such a phenomenon of noise-enhanced effect is termed stochastic resonance (SR). When signal is subthreshold, SR is observed by using Gaussian noise during iterative decoding. That is, the minimal bit error ratio (BER) is achieved at some non-zero noise intensity level. Besides, the larger the number of threshold devices is, the more remarkable the SR effect becomes. Especially when noise intensity is nearly optimal, BER approximates to zero after a few decoding iterations. Moreover, when Gaussian mixture noise is utilized, suprathreshold stochastic resonance (SSR) occurs in turbo decoding. These results show the beneficial effect of noise in channel coding and decoding. 相似文献
92.
The information fusion estimation problems are investigated for multi-sensor stochastic uncertain systems with correlated noises. The stochastic uncertainties caused by correlated multiplicative noises exist in the state and observation matrices. The process noise and the observation noises are one-step auto-correlated and two-step cross-correlated, respectively. While the observation noises of different sensors are one-step cross-correlated. The optimal centralized fusion filter, predictor and smoother are proposed in the linear minimum variance sense via an innovative analysis approach. To enhance the robustness and flexibility, a distributed fusion filter is put forward, which requires the calculation of filtering error cross-covariance matrices between any two local filters. To avoid the calculation of cross-covariance matrices, another distributed fusion filter is also presented by using the covariance intersection (CI) fusion algorithm, which can reduce the computational cost. A simulation example is given to show the effectiveness of the proposed algorithms. 相似文献
93.
A multi-product economic production quantity model with several real-world technical and physical constraints is developed in this paper. The cost function includes ordering, holding, backordering, lost sale, and the cost caused by unused space in the warehouse. The goal is to minimize the total inventory cost, where shortages are allowed and partially backordered with fixed and linear costs. The aim is to determine the length of the inventory cycle, the length of positive inventory period, and the backordering rates of the products during the shortage period in order to minimize the total inventory costs while satisfying all constraints. Due to complexity and non-linearity of the proposed model, sequential quadratic programming (SQP), stochastic fractal search (SFS), simulated annealing (SA), and water cycle algorithm (WCA) are utilized for solution. Ninety numerical examples in small, medium, and large sizes are solved to evaluate the efficiency of the solution methods. The performances of the solution methods are compared statistically. Besides, sensitivity analysis is performed to determine the effect of change in the main parameters of the problem on the objective function value and decision variables. 相似文献
94.
Jin Yu Fu;Jin Guan Lin;Guangying Liu;Hong Xia Hao; 《时间序列分析杂志》2024,45(4):613-638
This article introduces a novel approach that unifies two types of models: one is the continuous-time jump-diffusion used to model high-frequency market financial data, and the other is discrete-time GQARCH for modeling low-frequency financial data by embedding the discrete GQARCH structure with jumps in the instantaneous volatility process. This model is named GQARCH-Itô-Jumps model. Quasi-likelihood functions for the low-frequency GQARCH structure are developed for the parametric estimations. In the quasi-likelihood functions, for high-frequency financial data, the realized range-based estimations are adopted as the ‘observations’, rather than the realized return-based volatility estimators which entail the loss of intra-day information of the price movements. Meanwhile, the asymptotic properties are mainly established for the proposed estimators in the case of finite activity jumps. Moreover, simulation studies and some financial data are implemented to check the finite sample performance of the proposed methodology. 相似文献
95.
96.
The main purpose of this paper is to survey some recent progresses on control theory for stochastic distributed parameter systems, i.e., systems governed by stochastic differential equations in infinite dimensions, typically by stochastic partial differential equations. We will explain the new phenomenon and difficulties in the study of controllability and optimal control problems for one dimensional stochastic parabolic equations and stochastic hyperbolic equations. In particular, we shall see that both the formulation of corresponding stochastic control problems and the tools to solve them may differ considerably from their deterministic/finite-dimensional counterparts. More importantly, one has to develop new tools, say, the stochastic transposition method introduced in our previous works, to solve some problems in this field. 相似文献
97.
In this paper, we consider the estimation of the coefficient of a stochastic regression model whose explanatory variables and disturbances are permitted to exhibit short-memory or long-memory dependence. Three estimators of the coefficient are proposed. A variety of their asymptotics are illuminated under various assumptions on the explanatory variables and the disturbances. Numerical studies of the theoretical results are given. They show some unexpected aspects of the asymptotics of the three estimators. 相似文献
98.
建立一种非平稳随机过程整体推断方法。该方法首先提出随机过程整体参数函数的概念,然后通过仿真（或数字化设计）结果与试验曲线的有机结合,实现多种条件下试验曲线（多个随机过程）的整体推断,给出各种条件下随机过程的均值函数、方差函数和高可靠度的上、下限曲线,解决了非平稳、非各态历经随机过程和一种条件下只有一条样本曲线时产品可靠性评定的难题。 相似文献
99.
LTE-A是一种4G移动通信标准,可满足移动数据业务对传输带宽的要求。为解决移动通信网络中室内信号质量较差的问题,LTE-A标准采用飞蜂窝技术作为室内无线接入解决方案。针对LTE-A飞蜂窝网络的时延边界问题,运用随机网络演算方法分析业务流的自相似性质和MIMO信道的时变特性,构建了LTE-A飞蜂窝网络中自相似业务流的随机到达与随机服务模型。围绕所构建的到达与服务模型,运用有效带宽理论和chernoff界方法,给出了自相似业务流的端到端时延边界。NS3仿真验证表明,在信道带宽和业务流优先级等指标不同的情形下,所给出的理论端到端时延边界与仿真时延的偏差在2ms以内,较为准确有效,可为确保LTE-A飞蜂窝网络的服务质量提供依据。 相似文献
100.