全文获取类型
收费全文 | 5828篇 |
免费 | 251篇 |
国内免费 | 21篇 |
专业分类
电工技术 | 53篇 |
综合类 | 23篇 |
化学工业 | 1137篇 |
金属工艺 | 92篇 |
机械仪表 | 126篇 |
建筑科学 | 304篇 |
矿业工程 | 10篇 |
能源动力 | 226篇 |
轻工业 | 364篇 |
水利工程 | 58篇 |
石油天然气 | 31篇 |
无线电 | 515篇 |
一般工业技术 | 1185篇 |
冶金工业 | 835篇 |
原子能技术 | 46篇 |
自动化技术 | 1095篇 |
出版年
2023年 | 56篇 |
2022年 | 115篇 |
2021年 | 184篇 |
2020年 | 130篇 |
2019年 | 174篇 |
2018年 | 211篇 |
2017年 | 138篇 |
2016年 | 163篇 |
2015年 | 133篇 |
2014年 | 194篇 |
2013年 | 354篇 |
2012年 | 313篇 |
2011年 | 351篇 |
2010年 | 256篇 |
2009年 | 264篇 |
2008年 | 274篇 |
2007年 | 276篇 |
2006年 | 201篇 |
2005年 | 196篇 |
2004年 | 173篇 |
2003年 | 172篇 |
2002年 | 146篇 |
2001年 | 87篇 |
2000年 | 97篇 |
1999年 | 73篇 |
1998年 | 234篇 |
1997年 | 157篇 |
1996年 | 98篇 |
1995年 | 107篇 |
1994年 | 78篇 |
1993年 | 70篇 |
1992年 | 59篇 |
1991年 | 46篇 |
1990年 | 34篇 |
1989年 | 32篇 |
1988年 | 38篇 |
1987年 | 37篇 |
1986年 | 21篇 |
1985年 | 28篇 |
1984年 | 21篇 |
1983年 | 17篇 |
1982年 | 25篇 |
1981年 | 29篇 |
1980年 | 22篇 |
1979年 | 21篇 |
1978年 | 17篇 |
1977年 | 26篇 |
1976年 | 45篇 |
1975年 | 13篇 |
1972年 | 13篇 |
排序方式: 共有6100条查询结果,搜索用时 15 毫秒
21.
22.
23.
In this letter, based on the exact pairwise-error probability, we derive the union bound on the symbol-error probability (SEP) of the differential unitary space-time (DUST) modulation employing group codes. Instead of using the rank-and-determinant or Euclidean distance criteria, we optimize the cyclic group codes such that the union bound on the SEP is minimized for a predetermined scenario, taking into account the number of transmit and receive antennas and the operating signal-to-noise ratio (SNR). Our simulation results show that for a wide range of SNRs, the codes with the minimum union bound for a particular SNR outperform the codes designed based on rank-and-determinant or Euclidean distance criteria. 相似文献
24.
Simon P. Wilson Francisco J. Samaniego 《IEEE transactions on pattern analysis and machine intelligence》2007,33(3):198-208
In the literature on statistical inference in software reliability, the assumptions of parametric models and random sampling of bugs have been pervasive. We argue that both assumptions are problematic, the first because of robustness concerns and the second due to logical and practical difficulties. These considerations motivate the approach taken in this paper. We propose a nonparametric software reliability model based on the order-statistic paradigm. The objective of the work is to estimate, from data on discovery times observed within a type I censoring framework, both the underlying distribution F from which discovery times are generated and N, the unknown number of bugs in the software. The estimates are used to predict the next time to failure. The approach makes use of Bayesian nonparametric inference methods, in particular, the beta-Stacy process. The proposed methodology is illustrated on both real and simulated data 相似文献
25.
Simon Fitzgerald 《现代电视技术》2007,(1):148-148,150
陆虎(Land Rover)G4越野挑战赛.是各大汽车公司彼此互相交流的重大活动。经过三年多的精心准备.2006年G4挑战赛正式拉开了帷幕——一个月时间,18组挑战者.4000公里行程.跨越泰国、老挝、巴西和波利维亚。本届赛事是2003年G4挑战赛的延续.它的前身就是2000年结束的“骆驼杯”越野挑战赛。 相似文献
26.
In 3 eye-tracking experiments, the authors investigated the use of morphological information during pronoun resolution. Experiments 1 and 2 showed that disruption occurred when a preferred assignment was inconsistent with gender information. Experiment 2 ensured that this difficulty was not due to the introduction of a new discourse entity. Experiment 3 showed that disruption also occurred when number information was inconsistent with the preferred assignment. The results indicate that the use of morphological information is delayed until after the computation of coreference relations. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
27.
28.
A new evaluation model for SK combinator expressions is presented and used as a basis for the design of a novel processor. The resulting machine architecture resembles a dataflow ring, but executions are constrained to be fully lazy. An automatic dynamic load sharing mechanism for a distributed multiprocessor architecture is suggested, and initial simulation results are presented. 相似文献
29.
30.