全文获取类型
收费全文 | 300403篇 |
免费 | 7498篇 |
国内免费 | 1115篇 |
专业分类
电工技术 | 4690篇 |
综合类 | 333篇 |
化学工业 | 48004篇 |
金属工艺 | 9131篇 |
机械仪表 | 8285篇 |
建筑科学 | 8304篇 |
矿业工程 | 663篇 |
能源动力 | 8395篇 |
轻工业 | 37233篇 |
水利工程 | 2600篇 |
石油天然气 | 2108篇 |
武器工业 | 12篇 |
无线电 | 35452篇 |
一般工业技术 | 53944篇 |
冶金工业 | 55963篇 |
原子能技术 | 3566篇 |
自动化技术 | 30333篇 |
出版年
2022年 | 1993篇 |
2021年 | 3349篇 |
2020年 | 2466篇 |
2019年 | 2913篇 |
2018年 | 4513篇 |
2017年 | 4498篇 |
2016年 | 4910篇 |
2015年 | 3654篇 |
2014年 | 5564篇 |
2013年 | 15852篇 |
2012年 | 9766篇 |
2011年 | 12581篇 |
2010年 | 9801篇 |
2009年 | 10531篇 |
2008年 | 10950篇 |
2007年 | 10732篇 |
2006年 | 9580篇 |
2005年 | 8602篇 |
2004年 | 8190篇 |
2003年 | 8065篇 |
2002年 | 7439篇 |
2001年 | 7623篇 |
2000年 | 6865篇 |
1999年 | 7430篇 |
1998年 | 19228篇 |
1997年 | 13318篇 |
1996年 | 9878篇 |
1995年 | 7311篇 |
1994年 | 6325篇 |
1993年 | 6206篇 |
1992年 | 4259篇 |
1991年 | 4021篇 |
1990年 | 3739篇 |
1989年 | 3568篇 |
1988年 | 3490篇 |
1987年 | 2786篇 |
1986年 | 2641篇 |
1985年 | 3337篇 |
1984年 | 2969篇 |
1983年 | 2678篇 |
1982年 | 2494篇 |
1981年 | 2566篇 |
1980年 | 2402篇 |
1979年 | 2142篇 |
1978年 | 1976篇 |
1977年 | 2513篇 |
1976年 | 3427篇 |
1975年 | 1652篇 |
1974年 | 1555篇 |
1973年 | 1642篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
Journal of Materials Science - 相似文献
3.
Xiao Zhu Chen Yanxun Jiang Hongbo Hu Zhenzhen Lui John C. S. Min Geyong Dustdar Schahram 《Wireless Networks》2022,28(7):3305-3322
Wireless Networks - Unmanned aerial vehicles (UAV) have been widely used in various fields because of their high mobility and portability. At the same time, due to the rapid development of... 相似文献
4.
5.
6.
7.
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
8.
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
9.
Photoresponsive biomaterials are experiencing a transition from in vitro models to in vivo demonstrations that point toward clinical translation. Dynamic hydrogels for cell encapsulation, light-responsive carriers for controlled drug delivery, and nanomaterials containing photosensitizers for photodynamic therapy are relevant examples. Nonetheless, the step to the clinic largely depends on their combination with technologies to bring light into the body. This review highlights the challenge of photoactivation in vivo, and presents strategies for light management that can be adopted for this purpose. The authors’ focus is on technologies that are materials-driven, particularly upconversion nanoparticles that assist in “direct path” light delivery through tissue, and optical waveguides that “clear the path” between external light source and in vivo target. The authors’ intention is to assist the photoresponsive biomaterials community transition toward medical technologies by presenting light delivery concepts that can be integrated with the photoresponsive targets. The authors also aim to stimulate further innovation in materials-based light delivery platforms by highlighting needs and opportunities for in vivo photoactivation of biomaterials. 相似文献
10.
Esperanza González-Redondo 《建筑学研究前沿(英文版)》2022,11(2):255-277
The constructive analysis of Madrid's old timber-framed collective courtyard buildings, whether demolished, preserved intact, or enlarged, has achieved the dating of relevant case studies. New parameters established in this study set a chronology based on front sector original projects: old (1737–1788), pre-modern (1788–1847) and modern (1847–1892). The on-site inspection and archival research point to ongoing misleading construction in the historic Southern area. Some modern corralas erected on top of pre-existing buildings confirm the initial hypothesis. First dimensioning rules for new façades and the stability required in old ones before adding new storeys, maintaining the original masonry or double-layered system, are discovered. Undated buildings suggest their possible origin a la malicia and a later transformation into transitional corralas. Finally, an analysis of the demolished courtyards narrows down the dating and points to new conjectures in some preserved by showing their uneven layout, old features, and structural discordances in each sector. 相似文献