全文获取类型
收费全文 | 93019篇 |
免费 | 8000篇 |
国内免费 | 4074篇 |
专业分类
电工技术 | 5256篇 |
技术理论 | 9篇 |
综合类 | 5654篇 |
化学工业 | 15912篇 |
金属工艺 | 5448篇 |
机械仪表 | 6064篇 |
建筑科学 | 6495篇 |
矿业工程 | 2854篇 |
能源动力 | 2748篇 |
轻工业 | 5898篇 |
水利工程 | 1417篇 |
石油天然气 | 5549篇 |
武器工业 | 793篇 |
无线电 | 11031篇 |
一般工业技术 | 12077篇 |
冶金工业 | 4850篇 |
原子能技术 | 1156篇 |
自动化技术 | 11882篇 |
出版年
2024年 | 494篇 |
2023年 | 1749篇 |
2022年 | 2988篇 |
2021年 | 4256篇 |
2020年 | 3154篇 |
2019年 | 2736篇 |
2018年 | 2965篇 |
2017年 | 3254篇 |
2016年 | 2990篇 |
2015年 | 3892篇 |
2014年 | 4831篇 |
2013年 | 5800篇 |
2012年 | 6003篇 |
2011年 | 6615篇 |
2010年 | 5391篇 |
2009年 | 5229篇 |
2008年 | 5216篇 |
2007年 | 4820篇 |
2006年 | 4840篇 |
2005年 | 4007篇 |
2004年 | 2856篇 |
2003年 | 2511篇 |
2002年 | 2434篇 |
2001年 | 2113篇 |
2000年 | 2087篇 |
1999年 | 2135篇 |
1998年 | 1774篇 |
1997年 | 1510篇 |
1996年 | 1383篇 |
1995年 | 1100篇 |
1994年 | 894篇 |
1993年 | 603篇 |
1992年 | 494篇 |
1991年 | 400篇 |
1990年 | 336篇 |
1989年 | 288篇 |
1988年 | 211篇 |
1987年 | 147篇 |
1986年 | 117篇 |
1985年 | 85篇 |
1984年 | 64篇 |
1983年 | 64篇 |
1982年 | 53篇 |
1981年 | 37篇 |
1980年 | 34篇 |
1979年 | 23篇 |
1978年 | 16篇 |
1976年 | 24篇 |
1975年 | 10篇 |
1973年 | 15篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
论文提出了一种混沌通信系统的噪音衰减算法,该算法利用混沌同步现象在接收端获得正确的噪音估计值,从而从接收信号中滤除噪音恢复出正确的信号。通过数值仿真试验表明该方法是可行的。 相似文献
12.
论文将Fermat素性检验的思想运用于不可约多项式的判断,给出了一个对于不可约判断问题的Monte Carlo 算法,分析了该算法的计算复杂度问题,并且给出了次数在200以内的检验结果。 相似文献
13.
Min Song Weiying Zhu 《Communications Letters, IEEE》2004,8(7):479-481
This letter analyzes the saturated throughput for multicast switches with multiple input queues per input port. Under the assumptions of a Poisson uniform traffic model and random packet scheduling policy, we derive the multicast switch saturated throughput under different fanouts. To verify the analysis, extensive simulations are conducted with different switch sizes and fanouts. It is shown that the theoretical analysis and the simulation results have a discrepancy less than 1.9%. Results from this letter can be used as a guidance to design the optimal queuing for multicast switches. 相似文献
14.
15.
A mechanism of soldering of an aluminum alloy die casting to a steel die is proposed. A soldering critical temperature is
postulated, at which iron begins to react with aluminum to form an aluminum-rich liquid phase and solid intermetallic compounds.
The liquid joins the die with the casting upon solidification. The critical temperature is determined by the elements in both
the casting alloy and the die material and is equal to the solidus temperature of the resulting alloy. The critical temperature
is used to predict the onset of die soldering, and the local liquid fraction is related to the soldering tendency. Experiments
have been carried out to validate the concept and to determine the critical temperature for die soldering in an iron-aluminum
system. Thermodynamic calculations are used to determine the critical temperature and soldering tendency for the cases of
pure aluminum and a 380 alloy in a steel mold. Factors affecting the soldering tendency are discussed, and methods for reducing
die soldering are suggested. 相似文献
16.
17.
18.
19.
带隔板底水油藏油井临界产量计算公式 总被引:25,自引:9,他引:16
本给出了带隔板底水油藏油井的监界产量计算公式,它适用于所有带隔板底水油藏的油井。 相似文献
20.
R Gollamudi Z Feng EO Dillingham SE Bond G Han S Salgia 《Canadian Metallurgical Quarterly》1993,69(4):361-367
This investigation retrospectively examined changes in marital satisfaction following stroke. The relationship between such changes and other pertinent factors were also examined, including severity of aphasia, knowledge of aphasia, number of months after stroke, and length of the marriage. The subjects were 40 spouses of patients with aphasia grouped according to severity of the aphasia (mild, moderate, severe). Spouses completed two different measures of marital satisfaction--the Marital Satisfaction Scale (MSS) and the Marital Comparison Level Index (MCLI). These measures were completed in both a prestroke (retrospective reporting) and a poststroke format to allow for change to be assessed. In addition, a Knowledge of Aphasia questionnaire was completed by the normal spouses to evaluate their understanding of the disorder of aphasia. There was a significant difference between prestroke and poststroke scores on both the MSS and the MCLI, indicating a lower level of satisfaction following the stroke. The amount of change between prestroke and poststroke MSS and MCLI scores was not related to either number of months poststroke or number of years married. Although there was no relationship between changes in prestroke and poststroke scores on the MCLI and Knowledge of Aphasia scores, there was a significant correlation between changes in these scores on the MSS and Knowledge of Aphasia scores. Hence, the more knowledge spouses had regarding aphasia, the less the negative impact the stroke had on marital satisfaction, as measured by the MSS. Results are discussed in terms of the interdisciplinary treatment needs of aphasic patients and the implications for future investigations. 相似文献