全文获取类型
收费全文 | 63978篇 |
免费 | 2568篇 |
国内免费 | 2294篇 |
专业分类
电工技术 | 3169篇 |
技术理论 | 5篇 |
综合类 | 4036篇 |
化学工业 | 9430篇 |
金属工艺 | 1612篇 |
机械仪表 | 3101篇 |
建筑科学 | 4744篇 |
矿业工程 | 2493篇 |
能源动力 | 1031篇 |
轻工业 | 4400篇 |
水利工程 | 1228篇 |
石油天然气 | 5302篇 |
武器工业 | 446篇 |
无线电 | 4638篇 |
一般工业技术 | 3425篇 |
冶金工业 | 2775篇 |
原子能技术 | 379篇 |
自动化技术 | 16626篇 |
出版年
2024年 | 72篇 |
2023年 | 335篇 |
2022年 | 762篇 |
2021年 | 1103篇 |
2020年 | 1142篇 |
2019年 | 650篇 |
2018年 | 655篇 |
2017年 | 1023篇 |
2016年 | 1217篇 |
2015年 | 1355篇 |
2014年 | 3646篇 |
2013年 | 2671篇 |
2012年 | 3960篇 |
2011年 | 4404篇 |
2010年 | 3742篇 |
2009年 | 3764篇 |
2008年 | 3384篇 |
2007年 | 4634篇 |
2006年 | 4657篇 |
2005年 | 4479篇 |
2004年 | 3959篇 |
2003年 | 3749篇 |
2002年 | 2890篇 |
2001年 | 2404篇 |
2000年 | 1892篇 |
1999年 | 1455篇 |
1998年 | 1098篇 |
1997年 | 789篇 |
1996年 | 665篇 |
1995年 | 591篇 |
1994年 | 387篇 |
1993年 | 280篇 |
1992年 | 194篇 |
1991年 | 143篇 |
1990年 | 85篇 |
1989年 | 88篇 |
1988年 | 82篇 |
1987年 | 55篇 |
1986年 | 45篇 |
1985年 | 48篇 |
1984年 | 41篇 |
1983年 | 32篇 |
1982年 | 31篇 |
1981年 | 34篇 |
1980年 | 21篇 |
1979年 | 16篇 |
1978年 | 18篇 |
1977年 | 19篇 |
1976年 | 31篇 |
1975年 | 8篇 |
排序方式: 共有10000条查询结果,搜索用时 250 毫秒
21.
针对煤矿发生事故后传统救援监控系统无法实时对井下人员进行动态定位,导致矿井救援盲目性大、救援效率差、救援难度大等技术难题,为了进一步提高煤矿救援效率,通过技术研究,设计了一套以通信基站为核心的智能化救援监控系统,分析了该系统结构组成、工作原理,通过在担水沟煤矿井下实际应用效果来看,智能化救援监控系统对人员定位精准度达95%,实现人员动态位置三维成像,救援效率提高至80%以上,有效缩短了煤矿事故救援时间,取得了显著应用成效。 相似文献
22.
The paper focuses on the adaptive relational association rule mining problem. Relational association rules represent a particular type of association rules which describe frequent relations that occur between the features characterizing the instances within a data set. We aim at re-mining an object set, previously mined, when the feature set characterizing the objects increases. An adaptive relational association rule method, based on the discovery of interesting relational association rules, is proposed. This method, called ARARM (Adaptive Relational Association Rule Mining) adapts the set of rules that was established by mining the data before the feature set changed, preserving the completeness. We aim to reach the result more efficiently than running the mining algorithm again from scratch on the feature-extended object set. Experiments testing the method's performance on several case studies are also reported. The obtained results highlight the efficiency of the ARARM method and confirm the potential of our proposal. 相似文献
23.
Electrocardiogram is the most commonly used tool for the diagnosis of cardiologic diseases. In order to help cardiologists to diagnose the arrhythmias automatically, new methods for automated, computer aided ECG analysis are being developed. In this paper, a Modified Artificial Bee Colony (MABC) algorithm for ECG heart beat classification is introduced. It is applied to ECG data set which is obtained from MITBIH database and the result of MABC is compared with seventeen other classifier's accuracy.In classification problem, some features have higher distinctiveness than others. In this study, in order to find higher distinctive features, a detailed analysis has been done on time domain features. By using the right features in MABC algorithm, high classification success rate (99.30%) is obtained. Other methods generally have high classification accuracy on examined data set, but they have relatively low or even poor sensitivities for some beat types. Different data sets, unbalanced sample numbers in different classes have effect on classification result. When a balanced data set is used, MABC provided the best result as 97.96% among all classifiers.Not only part of the records from examined MITBIH database, but also all data from selected records are used to be able to use developed algorithm on a real time system in the future by using additional software modules and making adaptation on a specific hardware. 相似文献
24.
Rahul Sasidharan Pillai Matteo Frasnelli Vincenzo M. Sglavo 《Ceramics International》2018,44(2):1328-1333
The present work focuses on the fabrication of βTCP (β-tricalcium phosphate) and HA/βTCP (hydroxyapatite/β-tricalcium phosphate) composite coatings by plasma spraying. The starting powders were produced via solid-state method using 2 wt% MgO to stabilize βTCP phase. The synthesized powders were preliminarily granulated to be used by the plasma spray process. Coatings obtained on titanium substrates are uniform and well adherent but due to the high temperature and cooling rate typical for plasma spraying process, βTCP phase is almost totally transformed into the α allotrope. Thermal treatment at 800 °C allows the reconversion of the phase αTCP→ βTCP. It is therefore possible to produce coatings with tuneable dissolution properties by selecting the proper initial powder mixture and the specific thermal treatment. 相似文献
25.
26.
The veracity present in molecular data available in biological databases possesses new challenges for data analytics. The analysis of molecular data of various diseases can provide vital information for developing better understanding of the molecular mechanism of a disease. In this paper, an attempt has been made to propose a model that addresses the issue of veracity in data analytics for amino acid association patterns in protein sequences of Swine Influenza Virus. The veracity is caused by intra-sequential and inter-sequential biases present in the sequences due to varying degrees of relationships among amino acids. A complete dataset of 63,682 protein sequences is downloaded from NCBI and is refined. The refined dataset consists of 26,594 sequences which are employed in the present study. The type I fuzzy set is employed to explore amino acid association patterns in the dataset. The type I fuzzy support is refined to partially remove the inter-sequential biases causing veracity in data. The remaining inter-sequential biases present in refined fuzzy support are evaluated and eliminated using type II fuzzy set. Hence, it is concluded that a combination of type II fuzzy & refined fuzzy approach is the optimal approach for extracting a better picture of amino acid association patterns in the molecular dataset. 相似文献
27.
复合材料的最新进展与应用 总被引:2,自引:0,他引:2
叙述了复合材料的发展概况 ,详细介绍了增强材料的种类、性能、形式及加工技术 ,指出了复合材料具有广阔的应用前景 相似文献
28.
超声波强化原油破乳电脱盐技术的工业实践 总被引:9,自引:1,他引:8
报道了采用超声波强化原油破乳电脱盐技术的开发与工业应用.经过实验室开发确定的超声波强化原油破乳电脱盐专利技术--超声波-电场联合破乳脱盐组合技术采用顺逆流方式.该技术于2003年9月在齐鲁分公司完成工业应用试验后,超声波强化原油破乳设备直接投入生产运行,在不加入化学破乳剂的情况下,可使胜利混输原油(平均盐浓度为50 mg/L,平均水质量分数为0.5%~1.0%)脱后盐浓度低于3 mg/L,水质量分数小于0.3%. 相似文献
29.
30.