全文获取类型
收费全文 | 30119篇 |
免费 | 4114篇 |
国内免费 | 3272篇 |
专业分类
电工技术 | 4081篇 |
技术理论 | 2篇 |
综合类 | 5477篇 |
化学工业 | 697篇 |
金属工艺 | 566篇 |
机械仪表 | 2843篇 |
建筑科学 | 1479篇 |
矿业工程 | 1131篇 |
能源动力 | 811篇 |
轻工业 | 796篇 |
水利工程 | 1070篇 |
石油天然气 | 877篇 |
武器工业 | 600篇 |
无线电 | 2232篇 |
一般工业技术 | 1911篇 |
冶金工业 | 581篇 |
原子能技术 | 102篇 |
自动化技术 | 12249篇 |
出版年
2024年 | 91篇 |
2023年 | 333篇 |
2022年 | 606篇 |
2021年 | 666篇 |
2020年 | 883篇 |
2019年 | 811篇 |
2018年 | 796篇 |
2017年 | 931篇 |
2016年 | 1112篇 |
2015年 | 1249篇 |
2014年 | 1773篇 |
2013年 | 2006篇 |
2012年 | 2273篇 |
2011年 | 2575篇 |
2010年 | 1920篇 |
2009年 | 2078篇 |
2008年 | 2145篇 |
2007年 | 2614篇 |
2006年 | 2297篇 |
2005年 | 1911篇 |
2004年 | 1526篇 |
2003年 | 1322篇 |
2002年 | 1073篇 |
2001年 | 901篇 |
2000年 | 803篇 |
1999年 | 647篇 |
1998年 | 490篇 |
1997年 | 360篇 |
1996年 | 286篇 |
1995年 | 247篇 |
1994年 | 201篇 |
1993年 | 134篇 |
1992年 | 109篇 |
1991年 | 71篇 |
1990年 | 59篇 |
1989年 | 72篇 |
1988年 | 33篇 |
1987年 | 21篇 |
1986年 | 10篇 |
1985年 | 10篇 |
1984年 | 6篇 |
1983年 | 11篇 |
1982年 | 5篇 |
1981年 | 5篇 |
1980年 | 5篇 |
1979年 | 4篇 |
1977年 | 5篇 |
1962年 | 3篇 |
1959年 | 2篇 |
1957年 | 3篇 |
排序方式: 共有10000条查询结果,搜索用时 578 毫秒
11.
In this paper, the development of the models for the prediction of rock mass P wave velocity is presented. For model development, the database of 53 cases including widely used and recorded drilling parameters and P wave velocity was constructed from the field studies conducted in 13 open pit lignite mines. Both conventional linear, non-linear multiple regression and Adaptive Neuro Fuzzy Inference System (ANFIS) were used for model development. Prediction performance indicators showed that ANFIS model presented the best performance and it can successfully be used for the preliminary prediction of P wave velocities of rock masses. 相似文献
12.
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
13.
以基岩具有多斜面、多滑移通道的某实际重力坝工程为例,基于刚体极限平衡法,采用模糊理论和几种典型的体系可靠度计算方法,研究其典型坝段的坝基深层抗滑稳定模糊体系可靠度,探讨模糊理论中隶属函数形式、隶属度以及隶属函数中关键参数的取值对可靠度计算结果的影响。研究结果表明,采取限制失效概率模糊界限比的方法可使计算结果更具有参考性,考虑模糊性的抗滑稳定可靠指标的下限较常规可靠度计算值偏小,这在重力坝坝基抗滑稳定分析中应引起重视。 相似文献
14.
基于吴庄铁矿盘间柱宽度不确定性、两侧均为充填体且高度大的现状,为安全高效回采盘区间柱,制定了盘区间柱两侧采场充填体取芯设计方案,并对充填体进行制样,进行了实验室试块抗压强度试验。试验结果表明:一步骤采场(矿柱)充填体强度整体符合设计强度要求,二步采场充填体强度整体偏低,盘区间柱宽度较设计变化较大,宽度极其不规整,整体呈上窄下宽的规律。鉴于盘区间柱宽度不规则、二步骤采场充填体强度低于预期、采场高度大和盘区间柱回采时不能大面积暴露的特点,采用留设一定厚度间柱和采用较小采场长度的措施进行回采方案制定,制定了小采场分段空场嗣后充填法回采方案。该方案的制定和实施,对于其他类似地下矿山三步骤间柱回采工程具有借鉴意义。 相似文献
15.
The automatic design of controllers for mobile robots usually requires two stages. In the first stage, sensorial data are preprocessed or transformed into high level and meaningful values of variables which are usually defined from expert knowledge. In the second stage, a machine learning technique is applied to obtain a controller that maps these high level variables to the control commands that are actually sent to the robot. This paper describes an algorithm that is able to embed the preprocessing stage into the learning stage in order to get controllers directly starting from sensorial raw data with no expert knowledge involved. Due to the high dimensionality of the sensorial data, this approach uses Quantified Fuzzy Rules (QFRs), that are able to transform low-level input variables into high-level input variables, reducing the dimensionality through summarization. The proposed learning algorithm, called Iterative Quantified Fuzzy Rule Learning (IQFRL), is based on genetic programming. IQFRL is able to learn rules with different structures, and can manage linguistic variables with multiple granularities. The algorithm has been tested with the implementation of the wall-following behavior both in several realistic simulated environments with different complexity and on a Pioneer 3-AT robot in two real environments. Results have been compared with several well-known learning algorithms combined with different data preprocessing techniques, showing that IQFRL exhibits a better and statistically significant performance. Moreover, three real world applications for which IQFRL plays a central role are also presented: path and object tracking with static and moving obstacles avoidance. 相似文献
16.
Rui
Zhang Junmin Li Jianmin Jiao 《International Journal of Adaptive Control and Signal Processing》2020,34(7):919-936
This article investigates an adaptive fuzzy tracking control problem for a class of nontriangular form systems with asymmetric time-varying full state constraints. Unknown functions are approximated by the fuzzy logic systems. A domination approach is employed to tackle the nontriangular form structure. Time-varying asymmetric barrier Lyapunov functions (ABLFs) are adopted to ensure full-state constraints satisfaction. Based on the backstepping technique and time-varying ABLFs, an adaptive controller is proposed and guarantees that all the signals in the closed-loop system are ultimately bounded and the time-varying full state constraints are met. Simulation examples are presented to further demonstrate the effectiveness of the proposed approach. 相似文献
17.
基于信息熵理论和模糊物元分析理论,探讨了水库正常高水位的熵模糊物元决策模型.以待选方案与最优方案间的海明贴近度来决策水库正常高水位.在确定评价综合指标信息熵的熵权和专家知识权重的的过程中,充分挖掘待选方案的固有信息和避免个人主观因素的弊端.实例应用表明,该方法有效、可行. 相似文献
18.
基于多Agent的模糊粗交流 总被引:1,自引:0,他引:1
提出了变异模糊粗集的概念及其相应的性质和定理;建立了模糊粗交流最优传递序列的数学模型,并给出了解决此模型的算法思想,算例证明了算法思想的有效性。 相似文献
19.
结合松辽盆地大庆长垣西侧扶余、杨大城子油层的勘探实践,从顶生下储的特殊成藏原理出发,详细地讨论了扶余、杨大城子油层的油水层形成机理,提出了2种形成模式。认为扶杨油层的油水同层是在以上覆烃源岩的超压为驱动力的成藏条件下形成,油水混合运移注入储层,由于储层的孔喉小,油水重力分异不好,造成孔隙存油,喉道存水。这种低渗透储层孔隙结构复杂,含油饱和度低,油水在孔隙中分布状况特殊,使得电阻率等曲线反映流体的信息变弱,造成油水层识别变难。为此提出多参数降维油气水层识别方法,经实际应用取得较好的效果。 相似文献
20.
基于改进模糊综合评价法的水利工程社会评价研究 总被引:1,自引:0,他引:1
通过对水利工程社会评价及模糊综合评价法的介绍,讨论了模糊层次分析法中的一致性检验问题,并采用改进的模糊综合评价法对江垭水利枢纽工程进行社会评价,得到综合评价结果。 相似文献