全文获取类型
收费全文 | 65998篇 |
免费 | 3446篇 |
国内免费 | 141篇 |
专业分类
电工技术 | 628篇 |
综合类 | 256篇 |
化学工业 | 11594篇 |
金属工艺 | 1303篇 |
机械仪表 | 1316篇 |
建筑科学 | 2172篇 |
矿业工程 | 159篇 |
能源动力 | 1689篇 |
轻工业 | 8759篇 |
水利工程 | 579篇 |
石油天然气 | 312篇 |
武器工业 | 10篇 |
无线电 | 4402篇 |
一般工业技术 | 10855篇 |
冶金工业 | 16157篇 |
原子能技术 | 429篇 |
自动化技术 | 8965篇 |
出版年
2023年 | 462篇 |
2022年 | 505篇 |
2021年 | 1506篇 |
2020年 | 1199篇 |
2019年 | 1233篇 |
2018年 | 2081篇 |
2017年 | 2138篇 |
2016年 | 2158篇 |
2015年 | 1578篇 |
2014年 | 2161篇 |
2013年 | 3999篇 |
2012年 | 3486篇 |
2011年 | 3673篇 |
2010年 | 2798篇 |
2009年 | 2675篇 |
2008年 | 2832篇 |
2007年 | 2449篇 |
2006年 | 1902篇 |
2005年 | 1780篇 |
2004年 | 1770篇 |
2003年 | 1581篇 |
2002年 | 1480篇 |
2001年 | 1105篇 |
2000年 | 942篇 |
1999年 | 1088篇 |
1998年 | 5147篇 |
1997年 | 3187篇 |
1996年 | 2123篇 |
1995年 | 1326篇 |
1994年 | 1092篇 |
1993年 | 1138篇 |
1992年 | 416篇 |
1991年 | 493篇 |
1990年 | 443篇 |
1989年 | 395篇 |
1988年 | 390篇 |
1987年 | 319篇 |
1986年 | 341篇 |
1985年 | 380篇 |
1984年 | 307篇 |
1983年 | 219篇 |
1982年 | 276篇 |
1981年 | 284篇 |
1980年 | 265篇 |
1979年 | 213篇 |
1978年 | 189篇 |
1977年 | 334篇 |
1976年 | 637篇 |
1975年 | 167篇 |
1973年 | 128篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
22.
Dr. Tom Baladi Dr. Nedra Hamouda-Tekaya Dr. Leticia Christina Pires Gonçalves Dr. Stéphane Rocchi Dr. Cyril Ronco Dr. Rachid Benhida 《ChemMedChem》2020,15(13):1113-1117
Sulfonylguanidines are interesting bioactive compounds with a broad range of applications in the treatment of different pathologies. 2-Aminobenzazole-based structures are well employed in the development of new anticancer drugs. Two series of novel N-benzazol-2-yl-N′-sulfonyl guanidine derivatives were synthesized with the sulfonylguanidine in either an extra- or intracyclic frame. They were evaluated for their antiproliferative activity against malignant melanoma tumor cells, thus allowing structure-activity relationships to be defined. Additionally, NCI-60 screening was performed for the best analogue to study its efficiency against a panel of other cancer cell lines. The stability profile of this promising compound was then validated. During the synthetic process, an unexpected new deamidination of the sulfonylguanidine towards sulfonamide function was also identified. 相似文献
23.
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
24.
25.
Carla C. B. Brasil Cristiano R. de Menezes Eduardo Jacob-Lopes Juliano Smanioto Barin Leila Queiroz Zepka Paulo Cezar Bastianello Campagnol Roger Wagner Alexandre José Cichoski 《International Journal of Food Science & Technology》2020,55(3):1136-1144
This study investigated the effect of the combination of basic electrolysed water (BEW) and slightly acid electrolysed water (SAEW) with ultrasound (US) for cleaning and sanitation of the knives used in slaughtering processes. The knives were sonicated in a US bath using two modes of operation (normal and sweep) in two steps: (i) 5 min with BEW and (ii) 10 min with SAEW at 35 °C. The microbiological counts and the possible changes in the physical structure of the knives were evaluated. The association BEW + SAEW + US, in the sweep mode, provided lower mesophilic, enterobacterial, Staphylococcus aureus and yeast counts when compared to the values recommended by the international legislation. In addition, these conditions removed all organic residues from the knife blades and promoted the highest migration rate of the residues to the US water bath (12.35 mg/L·min), without modifications in the knife blades. Thus, cleaning and sanitation of knives was feasible with the association of BEW + SAEW + US, which could be a useful alternative for the meat industry. 相似文献
26.
27.
de Siqueira Gustavo Oliveira Canuto Sérgio Gonçalves Marcos André Laender Alberto H. F. 《International Journal on Digital Libraries》2020,21(1):61-73
International Journal on Digital Libraries - Throughout the history of science, different knowledge areas have collaborated to overcome major research challenges. The task of associating a... 相似文献
28.
Mkaouar Hana Zalila Bechir Hugues Jérôme Jmaiel Mohamed 《International Journal on Software Tools for Technology Transfer (STTT)》2020,22(2):219-247
International Journal on Software Tools for Technology Transfer - Formal methods have become a recommended practice in safety-critical software engineering. To be formally verified, a system should... 相似文献
29.
30.
Rosé Carolyn P. Järvelä Sanna 《International Journal of Computer-Supported Collaborative Learning》2020,15(3):249-255
International Journal of Computer-Supported Collaborative Learning - 相似文献