全文获取类型
收费全文 | 25654篇 |
免费 | 3395篇 |
国内免费 | 2349篇 |
专业分类
电工技术 | 531篇 |
技术理论 | 2篇 |
综合类 | 2112篇 |
化学工业 | 657篇 |
金属工艺 | 1376篇 |
机械仪表 | 685篇 |
建筑科学 | 1729篇 |
矿业工程 | 9401篇 |
能源动力 | 433篇 |
轻工业 | 338篇 |
水利工程 | 265篇 |
石油天然气 | 199篇 |
武器工业 | 49篇 |
无线电 | 1033篇 |
一般工业技术 | 800篇 |
冶金工业 | 3070篇 |
原子能技术 | 42篇 |
自动化技术 | 8676篇 |
出版年
2024年 | 49篇 |
2023年 | 223篇 |
2022年 | 629篇 |
2021年 | 867篇 |
2020年 | 1040篇 |
2019年 | 699篇 |
2018年 | 665篇 |
2017年 | 755篇 |
2016年 | 872篇 |
2015年 | 951篇 |
2014年 | 1726篇 |
2013年 | 1412篇 |
2012年 | 2230篇 |
2011年 | 2124篇 |
2010年 | 1685篇 |
2009年 | 1813篇 |
2008年 | 1882篇 |
2007年 | 2047篇 |
2006年 | 1827篇 |
2005年 | 1558篇 |
2004年 | 1358篇 |
2003年 | 1250篇 |
2002年 | 851篇 |
2001年 | 651篇 |
2000年 | 574篇 |
1999年 | 390篇 |
1998年 | 293篇 |
1997年 | 201篇 |
1996年 | 188篇 |
1995年 | 150篇 |
1994年 | 134篇 |
1993年 | 89篇 |
1992年 | 67篇 |
1991年 | 49篇 |
1990年 | 22篇 |
1989年 | 22篇 |
1988年 | 24篇 |
1987年 | 15篇 |
1986年 | 5篇 |
1985年 | 2篇 |
1984年 | 1篇 |
1983年 | 4篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1979年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 328 毫秒
11.
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
12.
The use of geothermal energy and its associated technologies has been increasing worldwide. However, there has been little paradigmatic research conducted in this area. This paper proposes a systematic methodology to research the development trends for the sustainable development of geothermal energy. A novel data analysis system was created to research the geothermal energy utilization trends, and a technological paradigm theory was adopted to explain the technological changes. A diffusion velocity model was used to simulate and forecast the geothermal power generation development in the diffusion phase. Simulation results showed that the development of installed capacity for geothermal generation had a strong inertia force along with the S-curve. Power generation from geothermal power sources reached a peak in 2008 and is estimated to be saturated by 2030. Geothermal energy technologies in hybrid power systems based on other renewable energy sources look to be more promising in the future. 相似文献
13.
针对新桥煤矿2301综采工作面机载喷雾系统喷雾效果差、喷雾耗水量大造成煤质含水量超标、喷嘴雾化程度不高、喷嘴容易发生堵塞等问题,提出了高压喷雾系统设计方案,选择了1.2mm的锥形引射喷嘴和1.5mm的扇形引射喷嘴。采用固定水泵供水方式,结合工作面实际情况,计算出喷雾总用水量247.5L/min,提高了喷雾射程,提升了除尘效果。 相似文献
14.
15.
如何在海量不确定数据集中提高频繁模式挖掘性能是目前研究的热点.传统算法大多是以期望、概率或者权重等单一指标为数据项集支持度,在大数据背景下,同时考虑概率和权重支持度的算法难以兼顾其执行效率.为此,本文提出一种基于Spark的不确定数据集频繁模式挖掘算法(UWEFP),首先,为了同时兼顾数据项的概率和权重,计算一项集的最大概率权重值并进行剪枝;然后,为了减少对数据集的多次扫描,结合Spark框架的优点,设计了一种具有FP-tree特征的新颖的UWEFP-tree结构进行模式树的构建及挖掘;最后在Spark环境下,以UCI数据集进行实验验证.实验结果表明本文的方法在保证挖掘结果的同时,提高了效率. 相似文献
16.
Mechanical behavior of a two-dimensional elastoplastic solid with rectilinear cracks is investigated. Plastic strip model is used to reduce plasticity problem to the equivalent linear elasticity formulation. Two realizations of the mixed mode plastic strip model are considered: in-line plastic strips as proposed by Becker and Gross [Int. J. Fract. 37 (1988) 163], and inclined plastic strips of Panasyuk and Savruk [Appl. Mech. Rev. 47 (1994) 151]. The effective mechanical response predictions are based on the procedure presented in Kachanov et al., [Appl. Mech. Rev. 47 (1994) 151]. Stress-strain relations are obtained for parallel and randomly oriented non-interacting cracks. Results are compared with known elastic solutions. 相似文献
17.
探讨分类挖掘技术在高校实际工作中的应用方式与应用领域。以高校人事管理为模型,应用数据挖掘中决策树算法,对高校人力资源数据源中的信息进行分析,发现其中有价值的数据模式,寻找其中存在的关系和规则,对高校人才规划提供比较客观的决策支持。 相似文献
18.
19.
Xu Baowen Zhang Weifeng 《电子科学学刊(英文版)》2002,19(4)
The users' interest can be mined from the web cache and can be used widely. The interest can be specialized by the two-tuple (term, weight) in the simple interest model, in which the association relations are not mined, and then the interest cannot be associated in expressing the users' interest. Based on analyzing the WWW cache model, this letter brings forward a two-dimensional interest model and gives the interrelated methods on how to store the two-dimensional interest model effectively. 相似文献
20.
XuBaowen ZhangWeifeng 《电子科学学刊(英文版)》2002,19(4):399-402
The users‘ interest can be mined from the web cache and can be used widely.The interest can be specialized by the two-tuple(term,weight) in the simple interest model,in which the association relations are not mined.and then interest cannot be associated in expressing the users‘interest.Based on analyzing the WWW cache model,this letter brings forward a twodimensional interest model and gives the interrelated methods on how to store the two-dimensional interest model effectively. 相似文献