全文获取类型
收费全文 | 506079篇 |
免费 | 4049篇 |
国内免费 | 1137篇 |
专业分类
化学 | 248034篇 |
晶体学 | 7761篇 |
力学 | 25602篇 |
综合类 | 13篇 |
数学 | 70687篇 |
物理学 | 159168篇 |
出版年
2020年 | 3513篇 |
2019年 | 3890篇 |
2018年 | 12024篇 |
2017年 | 12670篇 |
2016年 | 10712篇 |
2015年 | 5183篇 |
2014年 | 7336篇 |
2013年 | 18182篇 |
2012年 | 17393篇 |
2011年 | 26543篇 |
2010年 | 17602篇 |
2009年 | 17384篇 |
2008年 | 23881篇 |
2007年 | 26838篇 |
2006年 | 15158篇 |
2005年 | 18609篇 |
2004年 | 15060篇 |
2003年 | 13951篇 |
2002年 | 12134篇 |
2001年 | 12383篇 |
2000年 | 9749篇 |
1999年 | 7369篇 |
1998年 | 6306篇 |
1997年 | 6238篇 |
1996年 | 5957篇 |
1995年 | 5509篇 |
1994年 | 5519篇 |
1993年 | 5151篇 |
1992年 | 5812篇 |
1991年 | 5883篇 |
1990年 | 5702篇 |
1989年 | 5399篇 |
1988年 | 5534篇 |
1987年 | 5468篇 |
1986年 | 5153篇 |
1985年 | 6839篇 |
1984年 | 7240篇 |
1983年 | 6018篇 |
1982年 | 6321篇 |
1981年 | 6220篇 |
1980年 | 6065篇 |
1979年 | 6134篇 |
1978年 | 6489篇 |
1977年 | 6375篇 |
1976年 | 6486篇 |
1975年 | 5979篇 |
1974年 | 6042篇 |
1973年 | 6311篇 |
1972年 | 4304篇 |
1971年 | 3521篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
E. V. Shadrina O. N. Malinkina T. G. Khonina A. B. Shipovskaya V. I. Fomina E. Yu. Larchenko N. A. Popova I. G. Zyryanova L. P. Larionov 《Russian Chemical Bulletin》2015,64(7):1633-1639
The biomimetic sol—gel synthesis of silicon—chitosan-containing glycerohydrogels was carried out using silicon tetraglycerolate as a precursor. It was found that chitosan accelerates gel formation in weakly acidic media. In more acidic media, the kinetics of the process changes according to the curve with a maximum, which can be attributed to different mechanisms of silanol condensation before and after the isoelectric point. The investigated silicon—chitosan-containing glycerohydrogels exhibit antibacterial, anti-inflammatory, and wound healing activity. The synthesized hybrid glycerohydrogels are promising materials for biomedical applications. 相似文献
42.
43.
44.
45.
46.
47.
Yingchun Wu Haipeng Li Xuecheng Wu Gérard Gréhan Lutz Mädler Cyril Crua 《Proceedings of the Combustion Institute》2019,37(3):3211-3218
Droplet evaporation characterization, although of great significance, is still challenging. The recently developed phase rainbow refractometry (PRR) is proposed as an approach to measuring the droplet temperature, size as well as evaporation rate simultaneously, and is applied to a single flowing n-heptane droplet produced by a droplet-on-demand generator. The changes of droplet temperature and evaporation rate after a transient spark heating are reflected in the time-resolved PRR image. Results show that droplet evaporation rate increases with temperature, from ?1.28 m2/s at atmospheric 293 K to a range of (?1.5, ?8) m2/s when heated to (294, 315) K, agreeing well with the Maxwell and Stefan–Fuchs model predictions. Uncertainty analysis suggests that the main source is the indeterminate gradient inside droplet, resulting in an underestimation of droplet temperature and evaporation rate. With the demonstration on simultaneous measurements of droplet refractive index as well as droplet transient and local evaporation rate in this work, PRR is a promising tool to investigate single droplet evaporation in real engine conditions. 相似文献
48.
49.
50.
J. Conrad J. Cohen-Tanugi L. E. Strigari 《Journal of Experimental and Theoretical Physics》2015,121(6):1104-1135
The launch of the gamma-ray telescope Fermi Large Area Telescope (Fermi-LAT) started a pivotal period in indirect detection of dark matter. By outperforming expectations, for the first time a robust and stringent test of the paradigm of weakly interacting massive particles (WIMPs) is within reach. In this paper, we discuss astrophysical targets for WIMP detection and the challenges they present, review the analysis tools which have been employed to tackle these challenges, and summarize the status of constraints on and the claimed detections in the WIMP parameter space. Methods and results will be discussed in comparison to Imaging Air Cherenkov Telescopes. We also provide an outlook on short term and longer term developments. 相似文献