全文获取类型
收费全文 | 532589篇 |
免费 | 10151篇 |
国内免费 | 2581篇 |
专业分类
电工技术 | 10336篇 |
技术理论 | 5篇 |
综合类 | 2091篇 |
化学工业 | 80160篇 |
金属工艺 | 20259篇 |
机械仪表 | 15966篇 |
建筑科学 | 13294篇 |
矿业工程 | 3032篇 |
能源动力 | 11935篇 |
轻工业 | 48492篇 |
水利工程 | 5716篇 |
石油天然气 | 9134篇 |
武器工业 | 320篇 |
无线电 | 58840篇 |
一般工业技术 | 97304篇 |
冶金工业 | 108610篇 |
原子能技术 | 10070篇 |
自动化技术 | 49757篇 |
出版年
2021年 | 4734篇 |
2020年 | 3470篇 |
2019年 | 4382篇 |
2018年 | 7656篇 |
2017年 | 7803篇 |
2016年 | 8679篇 |
2015年 | 6249篇 |
2014年 | 9118篇 |
2013年 | 23239篇 |
2012年 | 16155篇 |
2011年 | 20780篇 |
2010年 | 15533篇 |
2009年 | 16782篇 |
2008年 | 17977篇 |
2007年 | 18025篇 |
2006年 | 15961篇 |
2005年 | 16724篇 |
2004年 | 15076篇 |
2003年 | 14074篇 |
2002年 | 12647篇 |
2001年 | 12541篇 |
2000年 | 11512篇 |
1999年 | 11791篇 |
1998年 | 30919篇 |
1997年 | 22035篇 |
1996年 | 16749篇 |
1995年 | 12365篇 |
1994年 | 10920篇 |
1993年 | 10824篇 |
1992年 | 7941篇 |
1991年 | 7444篇 |
1990年 | 7403篇 |
1989年 | 7060篇 |
1988年 | 6769篇 |
1987年 | 5880篇 |
1986年 | 5759篇 |
1985年 | 6644篇 |
1984年 | 6214篇 |
1983年 | 5680篇 |
1982年 | 5267篇 |
1981年 | 5594篇 |
1980年 | 5274篇 |
1979年 | 5136篇 |
1978年 | 4935篇 |
1977年 | 6049篇 |
1976年 | 8272篇 |
1975年 | 4475篇 |
1974年 | 4288篇 |
1973年 | 4332篇 |
1972年 | 3573篇 |
排序方式: 共有10000条查询结果,搜索用时 771 毫秒
1.
2.
3.
Zienko S. I. Zhbanova V. L. 《Journal of Communications Technology and Electronics》2022,67(4):395-402
Journal of Communications Technology and Electronics - A quantitative comparison of the spectral characteristics of the human visual system and matrix photodetectors is carried out. Criteria for a... 相似文献
4.
5.
Knaust Thiemo Felnhofer Anna Kothgassner Oswald D. Hllmer Helge Gorzka Robert-Jacek Schulz Holger 《Virtual Reality》2022,26(3):925-938
Virtual Reality - It is generally accepted that natural environments reduce stress and improve mood. Since access to natural environments is sometimes limited, virtual natural environments,... 相似文献
6.
Kuznetsov Yu. A. Markov M. A. Kravchenko I. N. Krasikov A. V. Bykova A. D. 《Refractories and Industrial Ceramics》2021,62(4):421-425
Refractories and Industrial Ceramics - The paper introduces a promising technology for utilizing a traditional scheme for implementing a flow-through micro-arc oxidation method to restore localized... 相似文献
7.
Engineering new glass compositions have experienced a sturdy tendency to move forward from (educated) trial-and-error to data- and simulation-driven strategies. In this work, we developed a computer program that combines data-driven predictive models (in this case, neural networks) with a genetic algorithm to design glass compositions with desired combinations of properties. First, we induced predictive models for the glass transition temperature (Tg) using a dataset of 45,302 compositions with 39 different chemical elements, and for the refractive index (nd) using a dataset of 41,225 compositions with 38 different chemical elements. Then, we searched for relevant glass compositions using a genetic algorithm informed by a design trend of glasses having high nd (1.7 or more) and low Tg (500 °C or less). Two candidate compositions suggested by the combined algorithms were selected and produced in the laboratory. These compositions are significantly different from those in the datasets used to induce the predictive models, showing that the used method is indeed capable of exploration. Both glasses met the constraints of the work, which supports the proposed framework. Therefore, this new tool can be immediately used for accelerating the design of new glasses. These results are a stepping stone in the pathway of machine learning-guided design of novel glasses. 相似文献
8.
Journal of Chemical Ecology - Biocontrol agents such as parasitic wasps use long-range volatiles and host-associated cues from lower trophic levels to find their hosts. However, this chemical... 相似文献
9.
Kathleen T. Lauser Amy L. Rueter Michelle A. Calabrese 《American Institute of Chemical Engineers》2022,68(12):e17850
While protein medications are promising for treatment of cancer and autoimmune diseases, challenges persist in terms of development and injection stability of high-concentration formulations. Here, the extensional flow properties of protein-excipient solutions are examined via dripping-onto-substrate extensional rheology, using a model ovalbumin (OVA) protein and biocompatible excipients polysorbate 20 (PS20) and 80 (PS80). Despite similar PS structures, differences in extensional flow are observed based on PS identity in two regimes: at moderate total concentrations where surface tension differences drive changes in extensional flow behavior, and at small PS:OVA ratios, which impact the onset of weakly elastic flow behavior. Undesirable elasticity is observed in ultra-concentrated formulations, independent of PS identity; higher PS contents are required to observe these effects than in analogous polymeric excipient solutions. These studies reveal novel extensional flow behaviors in protein-excipient solutions, and provide a straightforward methodology for assessing the extensional flow stability of new protein-excipient formulations. 相似文献
10.
Moghadam Seyedeh Hadis Ashofteh Parisa-Sadat Loáiciga Hugo A. 《Water Resources Management》2022,36(9):3181-3205
Water Resources Management - The water evaluation and planning (WEAP) approach and the invasive weed optimization algorithm (IWOA) are herein employed to determine the optimal operating policies in... 相似文献