全文获取类型
收费全文 | 34413篇 |
免费 | 3208篇 |
国内免费 | 1753篇 |
专业分类
电工技术 | 2529篇 |
技术理论 | 1篇 |
综合类 | 2464篇 |
化学工业 | 5538篇 |
金属工艺 | 1941篇 |
机械仪表 | 2141篇 |
建筑科学 | 2780篇 |
矿业工程 | 1121篇 |
能源动力 | 927篇 |
轻工业 | 2812篇 |
水利工程 | 753篇 |
石油天然气 | 2168篇 |
武器工业 | 293篇 |
无线电 | 3549篇 |
一般工业技术 | 3581篇 |
冶金工业 | 1537篇 |
原子能技术 | 423篇 |
自动化技术 | 4816篇 |
出版年
2024年 | 73篇 |
2023年 | 609篇 |
2022年 | 1014篇 |
2021年 | 1500篇 |
2020年 | 1120篇 |
2019年 | 899篇 |
2018年 | 995篇 |
2017年 | 1102篇 |
2016年 | 927篇 |
2015年 | 1411篇 |
2014年 | 1821篇 |
2013年 | 2155篇 |
2012年 | 2421篇 |
2011年 | 2700篇 |
2010年 | 2276篇 |
2009年 | 2176篇 |
2008年 | 2131篇 |
2007年 | 1982篇 |
2006年 | 1932篇 |
2005年 | 1696篇 |
2004年 | 1180篇 |
2003年 | 995篇 |
2002年 | 916篇 |
2001年 | 802篇 |
2000年 | 762篇 |
1999年 | 752篇 |
1998年 | 585篇 |
1997年 | 538篇 |
1996年 | 439篇 |
1995年 | 377篇 |
1994年 | 307篇 |
1993年 | 195篇 |
1992年 | 187篇 |
1991年 | 116篇 |
1990年 | 85篇 |
1989年 | 44篇 |
1988年 | 50篇 |
1987年 | 36篇 |
1986年 | 18篇 |
1985年 | 4篇 |
1984年 | 10篇 |
1983年 | 5篇 |
1982年 | 10篇 |
1981年 | 4篇 |
1980年 | 5篇 |
1979年 | 3篇 |
1959年 | 6篇 |
1951年 | 3篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
Wireless Networks - With the dynamic voltage scaling (DVS) technology, the terminal node (TN) can dynamically adjust its computational speed, thus providing a new way to save energy during task... 相似文献
3.
Neural Processing Letters - This paper is concerned with topology identification of stochastic multi-weighted complex networks based on adaptive synchronization. Different from previous work,... 相似文献
4.
5.
6.
Journal of Materials Science - The CsPbBr3/Cs4PbBr6 perovskite composite material has received wide attention due to its good stability and photoelectric properties, and it is promising to appear... 相似文献
7.
为提高Western Blotting结果的可靠性,以蛋白溶出率和凝胶电泳蛋白条带完整性为指标,比较提取液种类、研磨方式、酶抑制剂种类及其体积分数和提取时间对南美白对虾肝胰腺蛋白提取效果的影响。采用优化后的提取方法获得高质量蛋白样品,并采用Western Blotting法分析无水环境胁迫后南美白对虾肝胰腺组织中细胞凋亡信号通路相关蛋白的表达水平。结果表明:RIPA裂解液作为提取溶剂所得的蛋白溶出率高于水提和磷酸盐缓冲液,电动匀浆和液氮研磨所得蛋白条带更完整,4%蛋白酶磷酸酶混合抑制剂能有效抑制肝胰腺内源酶引起的蛋白降解;采用Western Blotting法分析无水保活期间南美白对虾肝胰腺蛋白,发现低温诱导休眠的同时会引起细胞轻微凋亡,且凋亡水平呈应激时间依赖性增加,环境胁迫解除后有所回调。 相似文献
8.
Farzaneh Khorasani Morteza Mohammadi Zanjireh Mahdi Bahaghighat Qin Xin 《计算机系统科学与工程》2022,40(3):1085-1098
With a sharp increase in the information volume, analyzing and retrieving this vast data volume is much more essential than ever. One of the main techniques that would be beneficial in this regard is called the Clustering method. Clustering aims to classify objects so that all objects within a cluster have similar features while other objects in different clusters are as distinct as possible. One of the most widely used clustering algorithms with the well and approved performance in different applications is the k-means algorithm. The main problem of the k-means algorithm is its performance which can be directly affected by the selection in the primary clusters. Lack of attention to this crucial issue has consequences such as creating empty clusters and decreasing the convergence time. Besides, the selection of appropriate initial seeds can reduce the cluster’s inconsistency. In this paper, we present a new method to determine the initial seeds of the k-mean algorithm to improve the accuracy and decrease the number of iterations of the algorithm. For this purpose, a new method is proposed considering the average distance between objects to determine the initial seeds. Our method attempts to provide a proper tradeoff between the accuracy and speed of the clustering algorithm. The experimental results showed that our proposed approach outperforms the Chithra with 1.7% and 2.1% in terms of clustering accuracy for Wine and Abalone detection data, respectively. Furthermore, achieved results indicate that comparing with the Reverse Nearest Neighbor (RNN) search approach, the proposed method has a higher convergence speed. 相似文献
9.
随着计算机技术的快速发展,虚拟仿真技术越发成熟,在教学中的应用越来越广泛.与传统线下实验教学模式相比,虚拟仿真技术具有安全无害,覆盖面广等优点,可以弥补传统实验教学模式中一些不足.本文主要以水银的处理实验为例,展示了虚拟仿真技术在危险性实验教学中的优势,为实验教学知识体系的完整性提供一个有力支持. 相似文献
10.
Xiaohui Wu Jingkang Xu Xingyu Huo Junbo Chen Qin Zhang Fangyi Huang Yuanxun Li Hua Su Lezhong Li 《Journal of the European Ceramic Society》2021,41(10):5193-5200
This work investigates the influence of niobium pentoxide (Nb2O5) as dopant, on the structural, magnetic, and dielectric properties of NiZnCo ferrites. The results showed that Nb2O5 was an effective dopant, and the Nb5+ ions entered the B site to replace Fe3+ ions, which altered the electromagnetic properties of the NiZnCo ferrite. In particular, the coercivity (Hc) was 20~24 Oe, and the magnetic quality factor (Q), was more than 200 at x = 0 and x = 0.1 wt%, which is 4~5 times higher than that of NiZn and NiCuZn ferrites. Excellent electromagnetic properties were obtained for 0.1 wt% Nb2O5-doped NiZnCo ferrite, i.e., Ms = 88.3 emu/g, Hc =20.4 Oe, ρ = 2.4 × 105 Ω m and Q = 202 @20 MHz. These excellent electromagnetic properties of Nb2O5-doped NiZnCo ferrites could be potentially applied to resonators and capacitors at high frequency. 相似文献