全文获取类型
收费全文 | 27690篇 |
免费 | 2491篇 |
国内免费 | 1153篇 |
专业分类
电工技术 | 1679篇 |
综合类 | 1934篇 |
化学工业 | 3502篇 |
金属工艺 | 1422篇 |
机械仪表 | 1851篇 |
建筑科学 | 2029篇 |
矿业工程 | 661篇 |
能源动力 | 810篇 |
轻工业 | 2932篇 |
水利工程 | 546篇 |
石油天然气 | 692篇 |
武器工业 | 301篇 |
无线电 | 3516篇 |
一般工业技术 | 2336篇 |
冶金工业 | 2465篇 |
原子能技术 | 310篇 |
自动化技术 | 4348篇 |
出版年
2024年 | 51篇 |
2023年 | 300篇 |
2022年 | 722篇 |
2021年 | 1136篇 |
2020年 | 896篇 |
2019年 | 606篇 |
2018年 | 713篇 |
2017年 | 801篇 |
2016年 | 768篇 |
2015年 | 1171篇 |
2014年 | 1628篇 |
2013年 | 1964篇 |
2012年 | 2449篇 |
2011年 | 2622篇 |
2010年 | 2253篇 |
2009年 | 2145篇 |
2008年 | 2075篇 |
2007年 | 1827篇 |
2006年 | 1345篇 |
2005年 | 861篇 |
2004年 | 636篇 |
2003年 | 439篇 |
2002年 | 356篇 |
2001年 | 268篇 |
2000年 | 199篇 |
1999年 | 203篇 |
1998年 | 639篇 |
1997年 | 402篇 |
1996年 | 312篇 |
1995年 | 177篇 |
1994年 | 168篇 |
1993年 | 161篇 |
1992年 | 83篇 |
1991年 | 82篇 |
1990年 | 67篇 |
1989年 | 75篇 |
1988年 | 46篇 |
1987年 | 41篇 |
1986年 | 42篇 |
1985年 | 47篇 |
1984年 | 37篇 |
1983年 | 38篇 |
1982年 | 42篇 |
1981年 | 36篇 |
1980年 | 39篇 |
1979年 | 22篇 |
1978年 | 18篇 |
1977年 | 76篇 |
1976年 | 136篇 |
1975年 | 18篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Yuelong Ma Le Zhang Tianyuan Zhou Bingheng Sun Chen Hou Shunshun Yang Jin Huang Rui Wang Farida A. Selim Zhongying Wang Ming Li Hao Chen Yun Wang 《Journal of the European Ceramic Society》2021,41(4):2834-2846
Ce:Y3Al5O12 transparent ceramics (TCs) with appropriate emission light proportion and high thermal stability are significant to construct white light emitting diode devices with excellent chromaticity parameters. In this work, strategies of controlling crystal-field splitting around Ce3+ ion and doping orange-red emitting ion, were adopted to fabricate Ce:(Y,Tb)3(Al,Mn)5O12 TCs via vacuum sintering technique. Notably, 85.4 % of the room-temperature luminescence intensity of the TC was retained at 150 °C, and the color rendering index was as high as 79.8. Furthermore, a 12 nm red shift and a 16.2 % increase of full width at half maximum were achieved owing to the synergistic effects of Tb3+ and Mn2+ ions. By combining TCs with a 460 nm blue chip, a warm white light with a low correlated color temperature of 4155 K was acquired. Meanwhile, the action mechanism of Tb3+ ion and the energy transfer between Ce3+ and Mn2+ ions were verified in prepared TCs. 相似文献
2.
Dr. Thomas Le Bihan Dr. Cathryn H. S. Driver Dr. Thomas Ebenhan Dr. Nathalie Le Bris Dr. Jan Rijn Zeevaart Prof. Dr. Raphaël Tripier 《ChemMedChem》2021,16(5):809-821
An improved glucose-chelator-albumin bioconjugate (GluCAB) derivative, GluCAB-2Mal, has been synthesized and studied for in vivo 64Cu-PET/CT imaging in breast cancer mice models together with its first-generation analogue GluCAB-1Mal. The radioligand works on the principle of tumor targeting through the enhanced permeability and retention (EPR) effect with a supportive role played by glucose metabolism. [64Cu]Cu-GluCAB-2Mal (99 % RCP) exhibited high serum stability with immediate binding to serum proteins. In vivo experiments for comparison between tumor targeting of [64Cu]Cu-GluCAB-2Mal and previous-generation [64Cu]Cu-GluCAB-1Mal encompassed microPET/CT imaging and biodistribution analysis in an allograft E0771 breast cancer mouse model. Tumor uptake of [64Cu]Cu-GluCAB-2Mal was clearly evident with twice as much accumulation as compared to its predecessor and a tumor/muscle ratio of up to 5 after 24 h. Further comparison indicated a decrease in liver accumulation for [64Cu]Cu-Glu-CAB-2Mal. 相似文献
3.
Silicon - Quadruple gate FinFET is a promising candidate among other multi-gate MOS devices due to it’s better scalability and higher short channel effect suppression capability in advanced... 相似文献
4.
双锥-平面线栅结构的水平极化辐射波天线对辐射场半宽影响较小且架设方便、易于维护,掌握该型天线场分布规律是确定模拟器场均匀区、开展电磁脉冲效应实验的前提。利用天线理论研究双锥-平面线栅天线的场分布规律,结合数值模拟和实际天线试验对理论分析结果进行验证。结果表明:在天线结构和激励电压确定的条件下,双锥中心正下方辐射电场极化分量仅与测点到源的距离相关,二者呈反比;Oxz平面内以双锥中心为圆心的圆弧上任意一点辐射电场极化分量的幅值相等,并在同一时刻达到峰值;Oxz平面内同一水平线上的测点总辐射场幅值相等,方向沿测点所在圆弧的切线方向;各辐射场分量关于Oxz平面和Oyz平面对称分布;对于实际模拟器,地面反射会使辐射场波形下降沿陡降,导致地面附近辐射场半宽变小;线栅极板会影响附近的场分布,且极板外侧4个角点处的反射相对较强,其他位置辐射场分布与理论分析一致。 相似文献
5.
Quan Nguyen Minh Quoc Dat Lai Hoang Nguy Minh Minh Tu Tran Kieu Ngoc Lam Gia Uyen Le My Phung Hang Hoang Dung Nguyen Tran Diem Ai Chau Ngoc Thuc Trinh Doan 《International Journal of Food Science & Technology》2022,57(7):4507-4517
To prevent the adulteration of agricultural resources and provide a solution to enhance the green coffee bean supply chain, authentication using the near-infrared spectroscopy (NIRS) technique was investigated. Partial least square with discrimination analysis (PLS-DA) models combined with various preprocessing methods were built from NIR spectra of 153 Vietnamese green coffee samples. The model combined with the standard normal variate and the first order of derivative yielded excellent performance in predicting coffee species with the error cross-validation of 0.0261. PLS-DA model of mean centre and first-order derivative spectra also yielded good performance in verifying geographical indication of green coffee with the error of 0.0656. By contrast, the predicting abilities of post-harvest methods were poor. The overall results showed a high potential of the NIRS in online authentication practices. 相似文献
6.
Blanc Soline Lahmadi Abdelkader Le Gouguec Kévin Minier Marine Sleem Lama 《Wireless Networks》2022,28(8):3453-3476
Wireless Networks - Cryptographic algorithms that can provide both encryption and authentication are increasingly required in modern security architectures and protocols (e.g. TLS v1.3). Many... 相似文献
7.
Leš Kristian Schönewerk Jens Glenneberg Jens Jordan Carmen-Simona 《Journal of Materials Science》2022,57(28):13496-13514
Journal of Materials Science - The performance of solid polymer electrolytes is characterized by lower ionic conductivity than conventional liquid electrolytes but provides advantages in terms of... 相似文献
8.
9.
CoCrNiCux (x=0.16,0.33,0.75,and 1) without macro-segregation medium-entropy alloys (MEAs) was prepared using laser directed energy deposition (LDED).The microstructure and mechanical properties of CoCrNiCux alloys with increas-ing Cu content were investigated.The results indicate that a single matrix phase changes into a dual-phase structure and the tensile fracture behaviors convert from brittle to plastic pattern with increasing Cu content in CoCrNiCux alloys.In addi-tion,the tensile strength of CoCrNiCux alloys increased from 148 to 820 MPa,and the ductility increased from 1 to 11%with increasing Cu content.The nano-precipitated particles had a mean size of approximately 20 nm in the Cu-rich phase area,and a large number of neatly arranged misfit dislocations were observed at the interface between the two phases due to Cu-rich phase precipitation in the CoCrNiCu alloy.These misfit dislocations hinder the movement of dislocations during tensile deformation,as observed through transmission electron microscopy.This allows the CoCrNiCu alloy to reach the largest tensile strength and plasticity,and a new strengthening mechanism was achieved for the CoCrNiCu alloy.Moreover,twins were observed in the matrix phase after tensile fracture.Simultaneously,the dual-phase structure with different elastic moduli coordinated with each other during the deformation process,significantly improving the plasticity and strength of the CoCrNiCu alloy. 相似文献
10.
本文开发了一套制冷状态下某洁净厂房的温度特性模型,该模型相对Multizone模型结果更精确,相对CFD模型计算更快捷.运用该模型,对空调参数、室内设备散热量、室外参数等影响因素开展动态仿真,研究厂房整体及局部区域的温度特性,仿真结果与实测数据符合情况良好.结果 显示空调系统与室内散热量对厂房温度影响较大.厂房内设备散热量变化对所处区域影响最大.厂房连续运行时,室内参数对室温影响比室外参数明显,厂房停工休息时,厂房温度仅受室外参数影响. 相似文献