全文获取类型
收费全文 | 20990篇 |
免费 | 1712篇 |
国内免费 | 963篇 |
专业分类
电工技术 | 1050篇 |
技术理论 | 4篇 |
综合类 | 1399篇 |
化学工业 | 3979篇 |
金属工艺 | 1267篇 |
机械仪表 | 1190篇 |
建筑科学 | 1553篇 |
矿业工程 | 558篇 |
能源动力 | 526篇 |
轻工业 | 1293篇 |
水利工程 | 338篇 |
石油天然气 | 1326篇 |
武器工业 | 120篇 |
无线电 | 2381篇 |
一般工业技术 | 2699篇 |
冶金工业 | 1003篇 |
原子能技术 | 217篇 |
自动化技术 | 2762篇 |
出版年
2024年 | 92篇 |
2023年 | 386篇 |
2022年 | 556篇 |
2021年 | 793篇 |
2020年 | 633篇 |
2019年 | 553篇 |
2018年 | 584篇 |
2017年 | 678篇 |
2016年 | 549篇 |
2015年 | 767篇 |
2014年 | 935篇 |
2013年 | 1185篇 |
2012年 | 1260篇 |
2011年 | 1341篇 |
2010年 | 1242篇 |
2009年 | 1251篇 |
2008年 | 1141篇 |
2007年 | 1120篇 |
2006年 | 1099篇 |
2005年 | 998篇 |
2004年 | 677篇 |
2003年 | 660篇 |
2002年 | 692篇 |
2001年 | 561篇 |
2000年 | 527篇 |
1999年 | 639篇 |
1998年 | 501篇 |
1997年 | 414篇 |
1996年 | 380篇 |
1995年 | 340篇 |
1994年 | 296篇 |
1993年 | 199篇 |
1992年 | 159篇 |
1991年 | 126篇 |
1990年 | 79篇 |
1989年 | 99篇 |
1988年 | 53篇 |
1987年 | 29篇 |
1986年 | 19篇 |
1985年 | 15篇 |
1984年 | 13篇 |
1983年 | 5篇 |
1982年 | 6篇 |
1981年 | 8篇 |
1980年 | 4篇 |
1979年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
Guangbo Zeng Dongqing Zhang Liuming Yan Baohua Yue Ting Pan Yidong Hu Shufa He Hongbin Zhao Jiujun Zhang 《International Journal of Hydrogen Energy》2021,46(39):20664-20677
Side-chain optimized poly (2,6-dimethyl-1,4-phenylene oxide)-g-poly (styrene sulfonic acid) (PPO-g-PSSA) is designed with balanced water-resistance and sulfonation degree. The PPO-g-PSSA is synthesized by controlled atom-transfer radical polymerization (ATRP) from brominated poly (2,6-dimethyl-1,4-phenylene oxide) (PPO-xBr) and ethyl styrene-4-sulfonate and followed by hydrolysis. A series of PPO-g-PSSA are prepared possessing different bromination degree (x) of PPO-xBr and polymerization degree (m) of the side-chains and the water-resistances of the fabricated membranes are investigated. The results show that a PPO-g-PSSA at relatively low x (x < 0.2) and high m (m > 4) exhibits good balance between the water-resistance and the sulfonation degree. Namely, it displays suitable proton conductivity with compromised water-resistance. Moreover, a maximum ion exchange capacity (IEC) of 3.24 mmol g?1 is reached without the sacrifice of water-resistance. In addition, PPO-g-0.08PSSA-13 and PPO-g-0.14PSSA-4 are chosen characterized by thermogravimetric analysis, proton conductivities and mechanical properties. At 90% RH, the optimized PPO-g-0.08PPSA-13 possesses a proton conductivity of 37.9 mS cm?1 at 40 °C and 45.5 mS cm?1 at 95 °C, respectively. 相似文献
12.
Lingfeng Zhou Zhipeng Zeng Michael P. Brady Donovan N. Leonard Harry M. Meyer Yukinori Yamamoto Wenyuan Li Greg Collins Xingbo Liu 《International Journal of Hydrogen Energy》2021,46(41):21619-21633
The chromium (Cr) evaporation behavior of several different types of iron (Fe)-based AFA alloys and benchmark Cr2O3-forming Fe-based 310 and Ni-based 625 alloys was investigated for 500 h exposures at 800 °C to 900 °C in air with 10% H2O. The Cr evaporation rates from alumina-forming austenitic (AFA) alloys were ~5 to 35 times lower than that of the Cr2O3-forming alloys depending on alloy and temperature. The Cr evaporation behavior was correlated with extensive characterization of the chemistry and microstructure of the oxide scales, which also revealed a degree of quartz tube Si contamination during the test. Long-term oxidation kinetics were also assessed at 800 to 1000 °C for up to 10,000 h in air with 10% H2O to provide further guidance for SOFC BOP component alloy selection. 相似文献
13.
Fancong Zeng Yingrui Sui Yanjie Wu Dongyue Jiang Zhanwu Wang Fengyou Wang Bin Yao Lili Yang 《Ceramics International》2021,47(13):18376-18384
Element doping into the Cu2ZnSn(S,Se)4 (CZTSSe) absorber is an effective method to optimize the performance of thin film solar cells. In this study, the Cu2InxZn1-xSn(S,Se)4 (CIZTSSe) precursor film was deposited by magnetron cosputtering technique using indium (In) and quaternary Cu2ZnSnS4 (CZTS) as targets. Meanwhile, the In content was controlled using the direct current (DC) power on In target (PIn). A single kesterite CIZTSSe alloy was formed by successfully doping a small number of In3+ into the main lattice of CZTSSe. The partial Zn2+ cations were substituted by In3+ ions, resulting in improving properties of CZTSSe films. Morphological analysis showed that large grain CIZTSSe films could be obtained by doping In. The well-distributed, smooth, and dense film was obtained when the PIn was 30 W. The band gap of CIZTSSe could be continuously adjusted from 1.27 to 1.05 eV as PIn increased from 0 to 40 W. In addition, the CIZTSSe alloy thin film at PIn = 30 W exhibited the best p-type conductivity with Hall mobility of 6.87 cm2V?1s?1, which is a potential material as the absorption layer of high-performance solar cells. 相似文献
14.
15.
Tao Li Zehui Du Nobumichi Tamura Mao Ye Saikumar Inguva Wei Lu Xierong Zeng Shanming Ke Haitao Huang 《Journal of the European Ceramic Society》2018,38(4):1488-1497
(1-x)Pb(Zn1/3Nb2/3)O3-xPbTiO3 ((1-x)PZN-xPT in short) is one of the most important piezoelectric materials. In this work, we extensively investigated (1-x)PZN-xPT (x = 0.07–0.11) ferroelectric single crystals using in-situ synchrotron μXRD, complemented by TEM and PFM, to correlate microstructures with phase transitions. The results reveal that (i) at 25 °C, the equilibrium state of (1-x)PZN-xPT is a metastable orthorhombic phase for x = 0.07 and 0.08, while it shows coexistence of orthorhombic and tetragonal phases for x = 0.09 and x = 0.11, with all ferroelectric phases accompanied by ferroelastic domains; (ii) upon heating, the phase transformation in x = 0.07 is Orthorhombic → Monoclinic → Tetragonal → Cubic. The coexistence of ferroelectric tetragonal and paraelectric cubic phases was in-situ observed in x = 0.08 above Curie temperature (TC), and (iii) phase transition can be explained by the evolution of the ferroelectric and ferroelastic domains. These results disclose that (1-x)PZN-xPT are in an unstable regime, which is possible factor for its anomalous dielectric response and high piezoelectric coefficient. 相似文献
16.
Debin Wang Jingsong Liu Mengshi Zeng Chunmei Zhang Huiqin Li Hongtao Yu Ying Yuan Shuren Zhang 《Journal of the American Ceramic Society》2019,102(7):4029-4037
(1-x)Sr0.7Pb0.15Bi0.1TiO3-xBi4Ti3O12 ((1-x)SPBT-xBIT, x = 0-0.125) bulk ceramics were developed and calcined via the solid-state method, aimed at the application of pulsed power capacitors. The phase structures, temperature stability, hysteresis loop, and discharge properties were systematically investigated. Considering both the temperature stability and dielectric properties, 0.925SPBT-0.075BIT bulk ceramics with a capacitance variation satisfying the X7R specification were developed for pulsed power capacitors. The energy storage density was 0.252 J/cm3, and the ceramics showed high temperature stability at 80 kV/cm. The discharge current waveforms of the 0.925SPBT-0.075BIT ceramics were recorded. A high discharge power density of approximately 1.01 × 108 W/kg with an 8 Ω load resistor and short discharge period of 84 ns were achieved at 50 kV/cm. The good temperature stability properties and high power density show that the 0.925SPBT-0.075BIT ceramics are well suited for pulsed power capacitors with a wide temperature range. 相似文献
17.
Yong Pan Chen Zhu Wen Bin Zeng Pei Fu Chi Chen Bao Ming Xu Zhong Feng Gao 《Chembiochem : a European journal of chemical biology》2021,22(24):3431-3436
Rapid and sensitive point-of-care testing (POCT) is an extremely critical mission in practical applications, especially for rigorous military medicine, home health care, and in the third world. Here, we report a visual POCT method for adenosine triphosphate (ATP) detection based on Taylor rising in the corner of quadratic geometries between two rod surfaces. We discuss the principle of Taylor rising, demonstrating that it is significantly influenced by contact angle, surface tension, and density of the sample, which are controlled by ATP-dependent rolling circle amplification (RCA). In the presence of ATP, RCA reaction effectively suppresses Taylor-rising behavior, due to the increased contact angle, density, and decreased surface tension. Without addition of ATP, untriggered RCA reaction is favorable for Taylor rising, resulting in a significant height. With this proposed method, visual sensitive detection of ATP without the aid of other instruments is realized with only a 5 μL droplet, which has good selectivity and a low detection limit (17 nM). Importantly, this visual method provides a promising POCT tool for user-friendly molecular diagnostics. 相似文献
18.
Shanquan Chen Sicong Wei Fei Jin Shanming Ke Xierong Zeng Lang Chen Chuanwei Huang 《Ceramics International》2018,44(12):13695-13698
From the perspectives of scientific researches and practical applications, it is desirable to explore high operating temperature ferromagnetic films. The effect of biaxial strain on magnetic properties of (110)-oriented La0.7Sr0.3MnO3 films was studied. High quality La0.7Sr0.3MnO3 films were grown on (110)-oriented perovskite single crystal substrates using pulsed laser deposition, varying substrate-induced misfit strains from ??2.27–0.75%. A remarkable enhancement of Curie temperature has been achieved for (110)-oriented La0.7Sr0.3MnO3 films clamped with small misfit strains (i.e., grown on LAST (110)). The enhanced Curie temperature of (110)-oriented La0.7Sr0.3MnO3 films could be attributed to the misfit strain between the films and the underlying substrates and may have technological implication for applications at high temperature environments. 相似文献
19.
20.
Shuang Shao Yong Liu Chun-Shui Xu Ying-Xuan Xu Bin Wu Xiao-Shu Zeng Xian-Feng Lu Xiang-Jie Yang 《金属学报(英文版)》2015,(1):7-14
The microstructure and mechanical properties of Mg–6Zn–1Y and Mg–6Zn–3Y(wt%) alloys under different cooling rates were investigated. The results show that the second dendrite arm spacing(SDAS) of Mg–6Zn–1Y and Mg–6Zn–3Y is reduced by 32 and 30% with increasing cooling rates(Rc) from 10.2 to 23 K/s, which can be predicted using a empirical model of SDAS=68 R 0:45:45cand SDAS=73 R 0c, respectively. The compressive strength of both alloys increases with increasing the cooling rate, which is attributed to the increase of volume fraction(Vf) of secondary phases under high cooling rate. The interaction of the cooling rate and component with SDAS has been theoretically analyzed using interdependence theory. 相似文献