全文获取类型
收费全文 | 7783篇 |
免费 | 610篇 |
国内免费 | 10篇 |
专业分类
电工技术 | 84篇 |
综合类 | 4篇 |
化学工业 | 1963篇 |
金属工艺 | 116篇 |
机械仪表 | 199篇 |
建筑科学 | 333篇 |
矿业工程 | 15篇 |
能源动力 | 257篇 |
轻工业 | 1392篇 |
水利工程 | 89篇 |
石油天然气 | 60篇 |
无线电 | 416篇 |
一般工业技术 | 1201篇 |
冶金工业 | 733篇 |
原子能技术 | 29篇 |
自动化技术 | 1512篇 |
出版年
2024年 | 16篇 |
2023年 | 91篇 |
2022年 | 115篇 |
2021年 | 313篇 |
2020年 | 259篇 |
2019年 | 269篇 |
2018年 | 373篇 |
2017年 | 340篇 |
2016年 | 427篇 |
2015年 | 251篇 |
2014年 | 371篇 |
2013年 | 717篇 |
2012年 | 547篇 |
2011年 | 586篇 |
2010年 | 437篇 |
2009年 | 471篇 |
2008年 | 387篇 |
2007年 | 369篇 |
2006年 | 217篇 |
2005年 | 187篇 |
2004年 | 175篇 |
2003年 | 156篇 |
2002年 | 137篇 |
2001年 | 77篇 |
2000年 | 56篇 |
1999年 | 69篇 |
1998年 | 225篇 |
1997年 | 153篇 |
1996年 | 103篇 |
1995年 | 83篇 |
1994年 | 69篇 |
1993年 | 51篇 |
1992年 | 37篇 |
1991年 | 28篇 |
1990年 | 21篇 |
1989年 | 25篇 |
1988年 | 30篇 |
1987年 | 16篇 |
1986年 | 12篇 |
1985年 | 19篇 |
1984年 | 16篇 |
1983年 | 11篇 |
1982年 | 8篇 |
1981年 | 13篇 |
1980年 | 14篇 |
1979年 | 5篇 |
1978年 | 4篇 |
1977年 | 14篇 |
1976年 | 19篇 |
1975年 | 4篇 |
排序方式: 共有8403条查询结果,搜索用时 78 毫秒
1.
Brito Claúdia Esteves Marisa Peixoto Hugo Abelha António Machado José 《Wireless Networks》2022,28(3):1269-1277
Wireless Networks - Continuous ambulatory peritoneal dialysis (CAPD) is a treatment used by patients in the end-stage of chronic kidney diseases. Those patients need to be monitored using blood... 相似文献
2.
3.
Angel L. Ortiz Camila S. Rodrigues Fernando Guiberteau Yu Zhang 《Journal of the European Ceramic Society》2021,41(11):5728-5739
The microstructural development during crystallization firing of a commercially-available dental-grade nanostructured lithia-zirconia glass-ceramic (Vita Suprinity® PC) was unraveled using a wide battery of ex-situ and in-situ characterization techniques. It was found that the milling blocks are slightly crystallized glass-ceramics, with a complex chemical composition and consisting of partially de-polymerized glass plus lithium silicate (Li2SiO3) nanocrystals. It was also found that during crystallization firing the glassy matrix first reacts with part of the Li2SiO3 to form lithium disilicate (Li2Si2O5) at ~810?820 °C, and then lithium orthophosphate (Li3PO4) precipitates from the glass. This results in glass-ceramics with abundant nanocrystals embedded in a sparse zirconosilicate glass matrix (containing many other cations subsumed) that, due to its high viscosity, inhibited crystal growth. Therefore, these dental glass-ceramics are not reinforced with zirconia (ZrO2) crystals unless over-fired above ~890 °C and at the expense of its singular nanostructure. Finally, this study opens doors for optimizing the clinical performance of these dental glass-ceramics via microstructural tailoring. 相似文献
4.
Elangeni Ana Gilbert Javier Fernando Guastavino Carolina Guadalupe Gutierrez María Verónica Lancelle Karen Russell-White Marcelo César Murguía 《Journal of surfactants and detergents》2021,24(3):411-419
A novel series of cleavable alkyltrimethylammonium surfactants with different hydrocarbon chain lengths (C8–16) were synthesized. A carbonate break site inserted between the polar head and the hydrocarbon chain makes these compounds hydrolyzable. The reagents used are renewable, (bio)degradable, or reusable. The hydrolysis of these cleavable surfactants will lead to the generation of fatty alcohols and choline, which is an essential biological nutrient. The surface activities in aqueous solution of the synthesized carbonates fulfill the requirement of being good surfactants. In addition, the cleavable compounds containing n-decyl and n-dodecyl chains showed similar or higher antimicrobial activities when compared to a non-cleavable analog. 相似文献
5.
Rosa Vera Oladis T. de Rincón Jesús Ramirez Bárbara Valverde Andrés Díaz-Gómez Rodrigo Sánchez-González 《工业材料与腐蚀》2020,71(7):1125-1137
In this study, the behavior of carbon steel and galvanized steel in nontropical coastal marine environments was evaluated. Evaluation was carried out with specimens with dimensions of 10 cm × 10 cm × 0.3 cm. These specimens were exposed to four testing stations (Iquique, Mejillones, Los Vilos, and San Vicente), where racks were installed both at ground level (ground), as well as in the upper zone of electrical transmission towers (tower). In each station, 24 specimens of A36 carbon steel and galvanized steel were placed (12 each). The corrosivity of the environment was measured using the ISO 9223, 9225, and 9226 standards. The specimens were evaluated on-site, monthly, through visual inspection and photographic record. Once withdrawn, the corrosion rate was determined and the corrosion products were analyzed through Raman and Fourier-transform infrared. The results show that, in all cases, the corrosion rate is greater in the tower than on the ground. However, even though the Los Vilos station is located farther from the sea (3,500 vs. ≈500 m), the corrosion rate of steel in the tower is the highest. This is caused by the generation of HCl from the transformation of lepidocrocite into goethite, in the presence of low chloride content, which acidifies the steel/corrosion product interface. In the case of galvanized steel, the corrosion rate is a function of the chloride content in the atmosphere, obtaining an excellent correlation between both parameters. 相似文献
6.
7.
Sinenhlanhla N. Mthembu Dr. Anamika Sharma Prof. Fernando Albericio Prof. Beatriz G. de la Torre 《Chembiochem : a European journal of chemical biology》2020,21(14):1947-1954
Cysteine is present in a large number of natural and synthetic (bio)molecules. Although the thiol side chain of Cys can be in a free form, in most cases it forms a disulfide bond either with a second Cys (bridge) or with another thiol, as in the case of protecting groups. Efficient reduction of these disulfide bridges is a requirement for many applications of Cys-containing molecules in the fields of chemistry and biochemistry. Here we review reducing methods for disulfide bonds, taking into consideration the solubility of the substrates when selecting the appropriate reducing reagent. 相似文献
8.
Insects as Food: Fatty Acid Profiles,Lipid Classes,and sn‐2 Fatty Acid Distribution of Lepidoptera Larvae 下载免费PDF全文
9.
Effect of the doping time of the 1‐butyl‐3‐methylimidazolium ionic liquid cation on the Nafion membrane proprieties 下载免费PDF全文
Letícia G. da Trindade Letícia Zanchet Katiúscia M.N. Borba Josiane C. Souza Edson R. Leite Emilse M.A. Martini 《国际能源研究杂志》2018,42(11):3535-3543
Nafion membranes were prepared by incorporating in the polymer matrix the 1‐butyl‐3‐methylimidazolium (BMI+) ionic liquid cation at different doping levels. Increasing the doping time of the membranes with the ionic liquid results in increased incorporation of the BMI+ cation but a decrease in the bulk conductivity. The thermogravimetric analysis shows that the BMI+ cation incorporation increases the thermal stability of the membranes. The higher discharge efficiency of the fuel cell at 80°C was obtained by using Nafion membrane after 15 minutes of doping in the ionic liquid solution. 相似文献