全文获取类型
收费全文 | 10671篇 |
免费 | 1488篇 |
国内免费 | 1174篇 |
专业分类
电工技术 | 861篇 |
技术理论 | 1篇 |
综合类 | 1380篇 |
化学工业 | 440篇 |
金属工艺 | 209篇 |
机械仪表 | 560篇 |
建筑科学 | 1120篇 |
矿业工程 | 419篇 |
能源动力 | 248篇 |
轻工业 | 278篇 |
水利工程 | 391篇 |
石油天然气 | 428篇 |
武器工业 | 73篇 |
无线电 | 895篇 |
一般工业技术 | 1281篇 |
冶金工业 | 315篇 |
原子能技术 | 57篇 |
自动化技术 | 4377篇 |
出版年
2024年 | 46篇 |
2023年 | 231篇 |
2022年 | 340篇 |
2021年 | 392篇 |
2020年 | 451篇 |
2019年 | 453篇 |
2018年 | 365篇 |
2017年 | 458篇 |
2016年 | 519篇 |
2015年 | 459篇 |
2014年 | 784篇 |
2013年 | 866篇 |
2012年 | 836篇 |
2011年 | 827篇 |
2010年 | 671篇 |
2009年 | 672篇 |
2008年 | 613篇 |
2007年 | 645篇 |
2006年 | 565篇 |
2005年 | 481篇 |
2004年 | 428篇 |
2003年 | 301篇 |
2002年 | 309篇 |
2001年 | 230篇 |
2000年 | 205篇 |
1999年 | 169篇 |
1998年 | 130篇 |
1997年 | 137篇 |
1996年 | 118篇 |
1995年 | 109篇 |
1994年 | 92篇 |
1993年 | 58篇 |
1992年 | 51篇 |
1991年 | 44篇 |
1990年 | 48篇 |
1989年 | 26篇 |
1988年 | 21篇 |
1987年 | 23篇 |
1986年 | 18篇 |
1985年 | 13篇 |
1984年 | 19篇 |
1983年 | 14篇 |
1982年 | 24篇 |
1981年 | 15篇 |
1980年 | 11篇 |
1979年 | 14篇 |
1978年 | 14篇 |
1977年 | 8篇 |
1976年 | 4篇 |
1975年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
This paper presents a novel No-Reference Video Quality Assessment (NR-VQA) model that utilizes proposed 3D steerable wavelet transform-based Natural Video Statistics (NVS) features as well as human perceptual features. Additionally, we proposed a novel two-stage regression scheme that significantly improves the overall performance of quality estimation. In the first stage, transform-based NVS and human perceptual features are separately passed through the proposed hybrid regression scheme: Support Vector Regression (SVR) followed by Polynomial curve fitting. The two visual quality scores predicted from the first stage are then used as features for the similar second stage. This predicts the final quality scores of distorted videos by achieving score level fusion. Extensive experiments were conducted using five authentic and four synthetic distortion databases. Experimental results demonstrate that the proposed method outperforms other published state-of-the-art benchmark methods on synthetic distortion databases and is among the top performers on authentic distortion databases. The source code is available at https://github.com/anishVNIT/two-stage-vqa. 相似文献
2.
This paper presents a novel framework for generation expansion planning (GEP) of restructured power systems under uncertainty in a multi-period horizon, which includes generation investment from a price maker perspective. The investment problem is modeled as a bi-level optimization problem. The first level problem includes decisions related to investment in order to maximize total profit in the planning horizon. The second level problem consists of maximizing social welfare where the power market is cleared. Rival uncertainties on offering and investment are modeled using sets of scenarios. The bi-level optimization problem is then converted to a dynamic stochastic MPEC and represented as a mixed integer linear program (MILP) after linearization. The proposed framework is examined on a typical six-bus power network, MAZANDARAN regional electric company (MREC) transmission network as an area of IRAN interconnected power system and IEEE RTS 24-bus network. Simulation results confirm that the proposed framework can be a useful tool for analyzing the behavior of investments in electricity markets. 相似文献
3.
ABSTRACTThis paper presents an empirical assessment of four state-of-the-art risk-averse approaches to deal with the capacitated lot-sizing problem under stochastic demand. We analyse two mean-risk models based on the semideviation and on the conditional value-at-risk risk measures, and alternate first and second-order stochastic dominance approaches. The extensive computational experiments based on different instances characteristics and on a case-study suggest that CVaR exhibits a good trade-off between risk and performance, followed by the semideviation and first-order stochastic dominance approach. For all approaches, enforcing risk-aversion helps to reduce the cost-standard deviation substantially, which is usually accomplished via increasing production rates. Overall, we can say that very risk-averse decision-makers would be willing to pay an increased price to have a much less risky solution given by CVaR . In less risk-averse settings, though, semideviation and first-order stochastic dominance can be appealing alternatives to provide significantly more stable production planning costs with a marginal increase of the expected costs. 相似文献
4.
This paper is concerned with the problem of joint input and state estimation for linear stochastic systems with direct feedthrough. Based on the fact that each unknown input between any two time steps is always bounded, a novel improved algorithm is proposed. Compared with existing results, this algorithm can effectively enhance estimation accuracy. Moreover, the stability of the algorithm is also discussed. Finally, an illustrative example is given to demonstrate the effectiveness of the proposed approach. 相似文献
5.
Hashim A.
Hashim 《国际强度与非线性控制杂志
》2020,30(10):3848-3870
》2020,30(10):3848-3870
This paper introduces two novel nonlinear stochastic attitude estimators developed on the Special Orthogonal Group with the tracking error of the normalized Euclidean distance meeting predefined transient and steady‐state characteristics. The tracking error is confined to initially start within a predetermined large set such that the transient performance is guaranteed to obey dynamically reducing boundaries and decrease smoothly and asymptotically to the origin in probability from almost any initial condition. The proposed estimators produce accurate attitude estimates with remarkable convergence properties using measurements obtained from low‐cost inertial measurement units. The estimators proposed in continuous form are complemented by their discrete versions for the implementation purposes. The simulation results illustrate the effectiveness and robustness of the proposed estimators against uncertain measurements and large initialization error, whether in continuous or discrete form. 相似文献
6.
在广播电视行业不断发展条件下,电视专题节目制作也受到受众高度重视。这就应提高电视专题节目制作质量,在满足广大受众日常观看要求同时,使得我国广播电视行业向着现代化方向发展。针对电视专题节目制作进行研究,首先阐述电视专题节目制作特点,之后阐述电视专题节目制作质量问题和相关提升对策。在解决电视专题节目制作问题同时,提升电视专题节目制作质量,继而彰显电视专题节目制作优势。 相似文献
7.
8.
讨论了在VMI管理思想下对具有随机需求特性的多客户库存分配问题 ,重点论述了有效近似算法的设计过程 ,最后基于一组模拟数据给出了一个算例。 相似文献
9.
论文提出利用用户提供的个性化信息来随机产生关联大素数,保证了素数选取的随机化、个性化,提高了RSA算法的安全性。 相似文献
10.
The effects of parameter uncertainty on optimal policy have been a matter of interest for academics, and even for some policymakers,
for a long time. Two lines of literature have developed analytical results on this matter. The first line uses static models
and the second dynamic models. In this dynamic line most of the results are confined to models with a single state and a single
control variable.
In this paper we want to encourage the analysis of more general dynamic cases. To do so, the results in the dynamic line are
extended from one-state and one-control finite horizon models to models with a pair of control variables. We then discuss
some of the hurdles which must be surmounted for the results to be made more general and suggests some lines for further research.
JEL classification: C61; E61 相似文献