全文获取类型
收费全文 | 51433篇 |
免费 | 5568篇 |
国内免费 | 3164篇 |
专业分类
电工技术 | 3768篇 |
综合类 | 4555篇 |
化学工业 | 7340篇 |
金属工艺 | 3240篇 |
机械仪表 | 3355篇 |
建筑科学 | 4098篇 |
矿业工程 | 2055篇 |
能源动力 | 1523篇 |
轻工业 | 5032篇 |
水利工程 | 1371篇 |
石油天然气 | 2370篇 |
武器工业 | 701篇 |
无线电 | 5682篇 |
一般工业技术 | 5189篇 |
冶金工业 | 2298篇 |
原子能技术 | 740篇 |
自动化技术 | 6848篇 |
出版年
2024年 | 323篇 |
2023年 | 1097篇 |
2022年 | 2216篇 |
2021年 | 2928篇 |
2020年 | 2171篇 |
2019年 | 1652篇 |
2018年 | 1758篇 |
2017年 | 1932篇 |
2016年 | 1717篇 |
2015年 | 2577篇 |
2014年 | 3069篇 |
2013年 | 3593篇 |
2012年 | 4031篇 |
2011年 | 3995篇 |
2010年 | 3667篇 |
2009年 | 3508篇 |
2008年 | 3445篇 |
2007年 | 3246篇 |
2006年 | 2820篇 |
2005年 | 2201篇 |
2004年 | 1571篇 |
2003年 | 1138篇 |
2002年 | 1064篇 |
2001年 | 915篇 |
2000年 | 832篇 |
1999年 | 601篇 |
1998年 | 399篇 |
1997年 | 320篇 |
1996年 | 298篇 |
1995年 | 239篇 |
1994年 | 208篇 |
1993年 | 123篇 |
1992年 | 99篇 |
1991年 | 84篇 |
1990年 | 65篇 |
1989年 | 53篇 |
1988年 | 33篇 |
1987年 | 35篇 |
1986年 | 36篇 |
1985年 | 10篇 |
1984年 | 13篇 |
1983年 | 9篇 |
1982年 | 10篇 |
1981年 | 16篇 |
1980年 | 12篇 |
1979年 | 3篇 |
1976年 | 2篇 |
1965年 | 3篇 |
1959年 | 7篇 |
1951年 | 15篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
目前,DC-DC开关功率变换器的非线性现象的研究已发展到了混沌的控制与应用研究.本文论述了对DC-DC开关变换器的混沌现象及其应用,并展望了混沌开关变换器的应用前景. 相似文献
32.
33.
J. Jiang Fanghua Mei W. J. Meng G. B. Sinclair Sunggook Park 《Microsystem Technologies》2008,14(6):815-819
For direct imprinting of metals, hard materials such as diamond and SiC have been used to construct mold inserts in preference
to Si, despite the ease in fabricating Si-based micro-/nano- scale structures. In this communication, we demonstrate that
micron scale Al structures can be replicated with good fidelity at room temperature by compression molding with Si inserts
without incurring insert damage. We further report on results of a finite element analysis of the mechanics of the molding
process. The finite element results provide some understanding of the observed lack of damage to the Si inserts. 相似文献
34.
将常规的数字温度仪与压力计通过串行口和计算机连接,构建基于LabVIEW 8.0测定纯液体蒸发焓的虚拟仪器,实现实验数据的动态采集、实时显示、自动绘制p~T曲线并显示曲线方程、自动数据处理和写成结果报告等。应用结果表明:基于LabVIEW构建的测定纯液体蒸发焓的虚拟仪器,免除人工操作的繁琐和人为误差,测定乙醇和苯蒸发焓的相对误差分别为0.86%、-2.97%,提高了测量结果的准确度,且具有界面友好,操作简便和功能易扩展等诸多优点。 相似文献
35.
37.
压缩应力下(Tb,Dy)Fe2磁致伸缩的研究 总被引:5,自引:0,他引:5
本文利用自制的磁致伸缩测量仪和“jump”效应测量仪研究了在一定压强了多晶(Tb、Dy)Fe2棒的磁致伸缩,发现加压时,在一定工艺条件下制作的(Tb、Dy)Fe2棒会有磁致伸缩的变化。卸载后经过热处理,磁致伸缩值在不加压时也会维持一个高值。 相似文献
38.
To evaluate the impact of zinc sulfate (ZnSO4) concentration on the structural properties of the films, Cd1-xZnxS thin films were formed on glass substrates using chemical bath deposition (CBD) in this study. The effect of ZnSO4 precursor concentration on the surface morphology, optical properties, and morphological structure of the Cd1-xZnxS films was investigated. To study the impact of zinc doping content on the performance metrics of Cu(In1-xGax)Se2 (CIGS) cells in the experimental group and to improve the buffer layer thickness, simulations were run using one-dimensional solar cell capacitance simulator (SCAPS-1D) software. 相似文献
39.
Clinical information about a variety of disorders is available through blood cell counting, which is usually done by manual methods. However, manual methods are complex, time-consuming and susceptible to the subjective experience of inspectors. Although many efforts have been made to develop automated blood cell counting algorithms, the complexity of blood cell distribution and the highly overlapping nature of some red blood cells (RBCs) remain significant challenges that limit the improvement of analytical accuracy. Here, we proposed an end-to-end method for blood cell counting based on deep learning. Firstly, U-Net++ was used to segment the whole blood cell image into several regions of interest (ROI), and each ROI contains only one single cell or multiple overlapping cells. Subsequently, YOLOv5 was used to detect blood cells in each ROI. Specifically, we proposed several strategies, including fine classification of RBCs, adaptive adjustment for non-maximal suppression (NMS) threshold and blood cell morphology constraints to improve the accuracy of detection. Finally, the detection outcomes for each ROI were combined and superimposed. The results show that our method can effectively address the issue of high overlap and precisely segment and detect blood cells, with a 98.18% accuracy rate for blood cell counting. 相似文献
40.
Jine Zhang Xiaobing Chen Mengqin Wang Qinghua Zhang Wenxiao Shi Xiaozhi Zhan Meng Zhao Zhe Li Jie Zheng Hui Zhang Furong Han Huaiwen Yang Tao Zhu Banggui Liu Fengxia Hu Baogen Shen Yuansha Chen Yue Zhang Yunzhong Chen Weisheng Zhao Jirong Sun 《Advanced functional materials》2023,33(41):2306434
Ferromagnetic materials with a strong spin-orbit coupling (SOC) have attracted much attention in recent years because of their exotic properties and potential applications in energy-efficient spintronics. However, such materials are scarce in nature. Here, a proximity-induced paramagnetic to ferromagnetic transition for the heavy transition metal oxide CaRuO3 in (001)-(LaMnO3/CaRuO3) superlattices is reported. Anomalous Hall effect is observed in the temperature range up to 180 K. Maximal anomalous Hall conductivity and anomalous Hall angle are as large as ∼15 Ω−1 cm−1 and ∼0.93%, respectively, by one to two orders of magnitude larger than those of the typical 3d ferromagnetic oxides such as La0.67Sr0.33MnO3. Density functional theory calculations indicate the existence of avoid band crossings in the electronic band structure of the ferromagnetic CRO layer, which enhances Berry curvature thus strong anomalous Hall effects. Further evidences from polarized neutron reflectometry show that the CaRuO3 layers are in a fully ferromagnetic state (∼0.8 μB/Ru), in sharp contrast to the proximity-induced canted antiferromagnetic state in 5d oxides SrIrO3 and CaIrO3 (∼0.1 μB/Ir). More than that, the magnetic anisotropy of the (001)-(LaMnO3/CaRuO3) superlattices is eightfold symmetric, showing potential applications in the technology of multistate data storage. 相似文献