全文获取类型
收费全文 | 9569篇 |
免费 | 1537篇 |
国内免费 | 1144篇 |
专业分类
电工技术 | 601篇 |
综合类 | 1545篇 |
化学工业 | 601篇 |
金属工艺 | 125篇 |
机械仪表 | 615篇 |
建筑科学 | 575篇 |
矿业工程 | 135篇 |
能源动力 | 132篇 |
轻工业 | 298篇 |
水利工程 | 287篇 |
石油天然气 | 254篇 |
武器工业 | 170篇 |
无线电 | 1514篇 |
一般工业技术 | 1474篇 |
冶金工业 | 304篇 |
原子能技术 | 81篇 |
自动化技术 | 3539篇 |
出版年
2024年 | 53篇 |
2023年 | 167篇 |
2022年 | 333篇 |
2021年 | 381篇 |
2020年 | 443篇 |
2019年 | 388篇 |
2018年 | 394篇 |
2017年 | 405篇 |
2016年 | 469篇 |
2015年 | 435篇 |
2014年 | 593篇 |
2013年 | 691篇 |
2012年 | 693篇 |
2011年 | 688篇 |
2010年 | 535篇 |
2009年 | 562篇 |
2008年 | 585篇 |
2007年 | 602篇 |
2006年 | 549篇 |
2005年 | 453篇 |
2004年 | 399篇 |
2003年 | 333篇 |
2002年 | 284篇 |
2001年 | 250篇 |
2000年 | 226篇 |
1999年 | 176篇 |
1998年 | 131篇 |
1997年 | 132篇 |
1996年 | 95篇 |
1995年 | 127篇 |
1994年 | 93篇 |
1993年 | 66篇 |
1992年 | 69篇 |
1991年 | 54篇 |
1990年 | 61篇 |
1989年 | 57篇 |
1988年 | 54篇 |
1987年 | 23篇 |
1986年 | 28篇 |
1985年 | 18篇 |
1984年 | 12篇 |
1983年 | 11篇 |
1982年 | 16篇 |
1981年 | 10篇 |
1980年 | 7篇 |
1977年 | 10篇 |
1965年 | 7篇 |
1964年 | 8篇 |
1961年 | 12篇 |
1959年 | 9篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
《Expert systems with applications》2014,41(6):2957-2963
In this paper, we consider interactive fuzzy programming for multi-level 0–1 programming problems involving random variable coefficients both in objective functions and constraints. Following the probability maximization model together with the concept of chance constraints, the formulated stochastic multi-level 0–1 programming problems are transformed into deterministic ones. Taking into account vagueness of judgments of the decision makers, we present interactive fuzzy programming. In the proposed interactive method, after determining the fuzzy goals of the decision makers at all levels, a satisfactory solution is derived efficiently by updating satisfactory levels of the decision makers with considerations of overall satisfactory balance among all levels. For solving the transformed deterministic problems efficiently, we also introduce novel tabu search for general 0–1 programming problems. A numerical example for a three-level 0–1 programming problem is provided to illustrate the proposed method. 相似文献
102.
Woon Wong 《时间序列分析杂志》1997,18(2):181-194
A stationary multivariate time series { X t } is defined as linear if it can be written in the form X t = ∑∞ j =−∞ A j e t − j where A j are square matrices and e t are independent and identically distributed random vectors. If the e t } are normally distributed, then { X t is a multivariate Gaussian linear process. This paper is concerned with the testing of departures of a vector stationary process from multivariate Gaussianity and linearity using the bispectral approach. First the definition and properties of cumulants of random matrices are used to obtain the expressions for the higher-order cumulant and spectral vectors of a linear vector process as defined above. Then it is shown that linearity of a vector process implies constancy of the modulus square of its normalized higher-order spectra whereas the component of such a vector process does not necessarily have a linear representation. Finally, statistics for the testing of multivariate Gaussianity and linearity are proposed. 相似文献
103.
分析了PP-R(无规共聚聚丙烯)管材料MFR(熔体流动速率)的变化对力学性能的影响,着重通过双螺杆挤出机研究了PP—R管材料熔融挤出过程中影响MFR变化的因素。结果表明,合适的加工工艺控制和优良的抗氧体系是保证PP-R管材料加工过程中MFR稳定的前提。 相似文献
104.
Miguel Martínez-Espronceda Jesús D. Trigo Santiago Led H. Gilberto Barrón-González Javier Redondo Alfonso Baquero Luis Serrano 《Computer methods and programs in biomedicine》2014
Experiences applying standards in personal health devices (PHDs) show an inherent trade-off between interoperability and costs (in terms of processing load and development time). Therefore, reducing hardware and software costs as well as time-to-market is crucial for standards adoption. The ISO/IEEE11073 PHD family of standards (also referred to as X73PHD) provides interoperable communication between PHDs and aggregators. Nevertheless, the responsibility of achieving inexpensive implementations of X73PHD in limited resource microcontrollers falls directly on the developer. Hence, the authors previously presented a methodology based on patterns to implement X73-compliant PHDs into devices with low-voltage low-power constraints. That version was based on multitasking, which required additional features and resources. This paper therefore presents an event-driven evolution of the patterns-based methodology for cost-effective development of standardized PHDs. The results of comparing between the two versions showed that the mean values of decrease in memory consumption and cycles of latency are 11.59% and 45.95%, respectively. In addition, several enhancements in terms of cost-effectiveness and development time can be derived from the new version of the methodology. Therefore, the new approach could help in producing cost-effective X73-compliant PHDs, which in turn could foster the adoption of standards. 相似文献
105.
Abstract. A generalized autoregressive (GAR) process {Z ( t ) ; t = 0 , ±1, …} is defined to satisfy the recurrence relation Z(t) = Aθ (t)Z (t -l)+ u( t ), where {Aθ (t); t = 0,±1, …} is itself a stochastic process depending on a vector parameter θ and where {u( t ); t = 0, ±1, …} is white noise with Eu 2 ( t ) = a 2 . This paper develops theory and methodology and implementing the class of GAR processes for time series modeling and forecasting. Conditions on the 'parameter process' { A θ ( t ); t = 0, ±1, …} are obtained for the existence of a GAR process; necessary and sufficient conditions on { Aθ ( t ) ; t = 0, ±1, …} for existence of a stationary GAR process are also obtained. Procedures are developed for computing maximum likelihood estimates of the parameters 0 and u2 and for computing the minimum mean squared error forecasts for GAR processes. 相似文献
106.
针对现有的无证书签密方案存在安全性不高、计算效率较低等诸多不足, 在Sharmila签密方案的基础上, 设计了一种新的无双线性对的无证书安全签密方案, 并在随机预言模型下证明了方案具有机密性和不可伪造性。同时, 该方案不需要双线性对和指数运算, 并且在确保安全性的前提下, 仅比现有的最高效签密方案多出两次点乘运算。 相似文献
107.
108.
109.
提出一种基于条件随机场的车牌字符分割算法,能够对光照不均、相机拍摄角度造成的低图像质量的车牌图像,特别是日益增多的车牌边框与字符相连接车牌图像进行有效的字符分割。算法首先进行车牌图像校正,然后利用标注车牌数据进行模型学习,对车牌图像像素列进行分类识别,最后组合成车牌字符分割结果。理论分析与实验结果验证了算法的有效性。 相似文献
110.