全文获取类型
收费全文 | 228070篇 |
免费 | 18221篇 |
国内免费 | 9108篇 |
专业分类
电工技术 | 12424篇 |
技术理论 | 24篇 |
综合类 | 14145篇 |
化学工业 | 38781篇 |
金属工艺 | 13126篇 |
机械仪表 | 14520篇 |
建筑科学 | 17564篇 |
矿业工程 | 7503篇 |
能源动力 | 6420篇 |
轻工业 | 13461篇 |
水利工程 | 3584篇 |
石油天然气 | 16616篇 |
武器工业 | 1647篇 |
无线电 | 25139篇 |
一般工业技术 | 27320篇 |
冶金工业 | 12804篇 |
原子能技术 | 2248篇 |
自动化技术 | 28073篇 |
出版年
2024年 | 992篇 |
2023年 | 3799篇 |
2022年 | 6479篇 |
2021年 | 9044篇 |
2020年 | 7077篇 |
2019年 | 6011篇 |
2018年 | 6734篇 |
2017年 | 7539篇 |
2016年 | 6748篇 |
2015年 | 8856篇 |
2014年 | 11248篇 |
2013年 | 13278篇 |
2012年 | 14207篇 |
2011年 | 15444篇 |
2010年 | 13417篇 |
2009年 | 12678篇 |
2008年 | 12345篇 |
2007年 | 11849篇 |
2006年 | 12339篇 |
2005年 | 10746篇 |
2004年 | 7258篇 |
2003年 | 6225篇 |
2002年 | 5462篇 |
2001年 | 4885篇 |
2000年 | 5433篇 |
1999年 | 6440篇 |
1998年 | 5434篇 |
1997年 | 4451篇 |
1996年 | 4189篇 |
1995年 | 3499篇 |
1994年 | 2811篇 |
1993年 | 1965篇 |
1992年 | 1536篇 |
1991年 | 1227篇 |
1990年 | 933篇 |
1989年 | 741篇 |
1988年 | 537篇 |
1987年 | 336篇 |
1986年 | 278篇 |
1985年 | 196篇 |
1984年 | 139篇 |
1983年 | 114篇 |
1982年 | 124篇 |
1981年 | 98篇 |
1980年 | 70篇 |
1979年 | 36篇 |
1978年 | 26篇 |
1977年 | 20篇 |
1976年 | 35篇 |
1973年 | 13篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
151.
Functional expression and synergistic cooperation of xylan‐degrading enzymes from Hypocrea orientalis and Aspergillus niger 下载免费PDF全文
152.
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
153.
Baizhan Li Chenqiu Du Hong Liu Wei Yu Jie Zheng Meilan Tan Zhenxing Jin Wenjie Li Jing Wu Lu Chen Runming Yao 《Indoor air》2019,29(2):308-319
The extensive research interests in environmental temperature can be linked to human productivity / performance as well as comfort and health; while the mechanisms of physiological indices responding to temperature variations remain incompletely understood. This study adopted a physiological sensory nerve conduction velocity (SCV) as a temperature‐sensitive biomarker to explore the thermoregulatory mechanisms of human responding to annual temperatures. The measurements of subjects’ SCV (over 600 samples) were conducted in a naturally ventilated environment over all four seasons. The results showed a positive correlation between SCV and annual temperatures and a Boltzmann model was adopted to depict the S‐shaped trend of SCV with operative temperatures from 5°C to 40°C. The SCV increased linearly with operative temperatures from 14.28°C to 20.5°C and responded sensitively for 10.19°C‐24.59°C, while tended to be stable beyond that. The subjects’ thermal sensations were linearly related to SCV, elaborating the relation between human physiological regulations and subjective thermal perception variations. The findings reveal the body SCV regulatory characteristics in different operative temperature intervals, thereby giving a deeper insight into human autonomic thermoregulation and benefiting for built environment designs, meantime minimizing the temperature‐invoked risks to human health and well‐being. 相似文献
154.
155.
156.
157.
158.
159.
160.
Multifunctional 3D Patternable Drug‐Embedded Nanocarrier‐Based Interfaces to Enhance Signal Recording and Reduce Neuron Degeneration in Neural Implantation 下载免费PDF全文