全文获取类型
收费全文 | 29758篇 |
免费 | 2803篇 |
国内免费 | 1456篇 |
专业分类
电工技术 | 2005篇 |
技术理论 | 2篇 |
综合类 | 2076篇 |
化学工业 | 4715篇 |
金属工艺 | 1480篇 |
机械仪表 | 1993篇 |
建筑科学 | 2992篇 |
矿业工程 | 812篇 |
能源动力 | 824篇 |
轻工业 | 2407篇 |
水利工程 | 527篇 |
石油天然气 | 1330篇 |
武器工业 | 232篇 |
无线电 | 3649篇 |
一般工业技术 | 3470篇 |
冶金工业 | 1144篇 |
原子能技术 | 398篇 |
自动化技术 | 3961篇 |
出版年
2024年 | 67篇 |
2023年 | 533篇 |
2022年 | 886篇 |
2021年 | 1373篇 |
2020年 | 1012篇 |
2019年 | 830篇 |
2018年 | 896篇 |
2017年 | 999篇 |
2016年 | 930篇 |
2015年 | 1162篇 |
2014年 | 1543篇 |
2013年 | 1783篇 |
2012年 | 2016篇 |
2011年 | 2144篇 |
2010年 | 2004篇 |
2009年 | 1888篇 |
2008年 | 1738篇 |
2007年 | 1644篇 |
2006年 | 1575篇 |
2005年 | 1341篇 |
2004年 | 892篇 |
2003年 | 831篇 |
2002年 | 821篇 |
2001年 | 742篇 |
2000年 | 658篇 |
1999年 | 688篇 |
1998年 | 483篇 |
1997年 | 466篇 |
1996年 | 456篇 |
1995年 | 365篇 |
1994年 | 307篇 |
1993年 | 204篇 |
1992年 | 156篇 |
1991年 | 110篇 |
1990年 | 82篇 |
1989年 | 78篇 |
1988年 | 62篇 |
1987年 | 40篇 |
1986年 | 23篇 |
1985年 | 21篇 |
1984年 | 11篇 |
1983年 | 9篇 |
1982年 | 11篇 |
1981年 | 8篇 |
1980年 | 10篇 |
1979年 | 10篇 |
1977年 | 4篇 |
1962年 | 42篇 |
1961年 | 39篇 |
1960年 | 16篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Dr. Jie Zang Dr. Fei Ye Dr. Sara M. Ø. Solbak Dr. Lars J. Høj Prof. Mingjie Zhang Prof. Anders Bach 《ChemMedChem》2021,16(6):949-954
Inhibition of PSD-95 has emerged as a promising strategy for the treatment of ischemic stroke, as shown with peptide-based compounds that target the PDZ domains of PSD-95. In contrast, developing potent and drug-like small molecules against the PSD-95 PDZ domains has so far been unsuccessful. Here, we explore the druggability of the PSD-95 PDZ1-2 domain and use fragment screening to investigate if this protein is prone to binding small molecules. We screened 2500 fragments by fluorescence polarization (FP) and validated the hits by surface plasmon resonance (SPR), including an inhibition counter-test, and found four promising fragments. Three ligand efficient fragments were shown by 1H,15N HSQC NMR to bind in the small hydrophobic P0 pockets of PDZ1-2, and one of them underwent structure-activity relationship (SAR) studies. Overall, we demonstrate that fragment screening can successfully be applied to PDZ1-2 of PSD-95 and disclose novel fragments that can serve as starting points for optimization towards small-molecule PDZ domain inhibitors. 相似文献
2.
Telecommunication Systems - Machine to Machine technology has a broad application prospect in the 5G network, but there is a bottleneck in the energy consumption of intelligent devices powered by... 相似文献
3.
High purity AlN fiber is a promising thermal conductive material. In this work, AlN fibers were prepared using solution blow spinning followed by nitridation under N2 or NH3 atmosphere. Soluble polymer, such as polyaluminoxane, and allyl-functional novolac resin were adopted as raw materials to form homogeneous distribution of Al2O3 and C nanoparticles within the fibers, which could inhibit the growth of alumina crystal and promote their nitridation process. The effect of nitriding atmosphere on the fiber morphology was investigated. XRD results showed that complete nitridation was achieved at 1300 °C in the NH3 or at 1500 °C in the N2 atmosphere. Hollowed fiber structure was observed when fiber was nitrided in N2 at high temperature, which was caused by gaseous Al gas diffusion, and this phenomenon was eliminated in NH3 atmosphere. The nitridation mechanisms in different atmosphere were analyzed in detail. It was demonstrated that the nitridation of Al2O3 fibers in the NH3 atmosphere offered the favored AlN morphology and chemical quality. Flexible AlN fiber with O content of 0.7 wt% was achieved after nitriding in NH3 at 1400 °C. The high quality AlN can be used in thermal conductive composite materials. 相似文献
4.
5.
6.
7.
The slight-alkalization of generator internal cooling water (GICW) is widely used to inhibit the corrosion of hollow copper conductor and thereby ensure the safe operation of the generator. CO2 inleakage is increasingly identified as a potential security risk for GICW system. In this paper, the influence of CO2 inleakage on the slight-alkalization of GICW was theoretically discussed. Based on the equilibriums of the CO2-NaOH-H2O system, CO2 inleakage saturation was derived to quantify the amount of the dissolved CO2 in GICW. This parameter can be directly calculated with the measured conductivity and the [Na+] of GICW. The influence of CO2 inleakage on the slight-alkalization conditioning of GICW and the measurement of its water quality parameters were then analyzed. The more severe the inleakage, the narrower the water quality operation ranges of GICW, resulting in the more difficult the slight-alkalization conditioning of GICW. The temperature calibrations of the conductivity and the pH value of GICW show non-linear correlations with the amount of CO2 inleakage and the NaOH dosage. This study provides insights into the influence of CO2 inleakage on the slight-alkalization of GICW, which can serve as the theoretical basis for the actual slight-alkalization when CO2 inleakage occurs. 相似文献
8.
9.
Yung-Tang Nien Chang-Han Tsai Rui-He Zheng Hong-Jun Ye 《Ceramics International》2021,47(13):18550-18556
Cerium-doped yttrium aluminum garnet (Y3Al5O12:Ce, YAG:Ce) was prepared using a sol-gel method and then fired for CO2 laser post-treatments. Phase transformations and formation of impurities were not observed in YAG:Ce after CO2 laser sintering. The shift of the diffraction peak and the appearance of another Raman peak indicate a more homogeneous distribution of Ce activators and enhanced crystallinity in laser-sintered YAG hosts. Larger spheres (100–200 μm) with tiny crystallites (<10 μm) were observed on the smoother surface in the laser-sintered YAG:Ce, unlike the irregular, porous, and layered powders in the sol-gel-derived YAG:Ce (1–100 μm). Photoluminescence (PL) measurements revealed an emission increase of 180% and a red shift of the emission peak for the laser-sintered YAG:Ce powders compared with the sol-gel-derived powders. Both have comparable thermal PL quenching behavior; however, the YAG:Ce powders with CO2 laser treatment exhibited a PL efficiency improvement of approximately 4%. 相似文献