全文获取类型
收费全文 | 375716篇 |
免费 | 23190篇 |
国内免费 | 14857篇 |
专业分类
化学 | 190981篇 |
晶体学 | 4319篇 |
力学 | 15460篇 |
综合类 | 593篇 |
数学 | 36011篇 |
物理学 | 103322篇 |
无线电 | 63077篇 |
出版年
2023年 | 3567篇 |
2022年 | 4377篇 |
2021年 | 6551篇 |
2020年 | 6916篇 |
2019年 | 6774篇 |
2018年 | 6586篇 |
2017年 | 6608篇 |
2016年 | 9626篇 |
2015年 | 8394篇 |
2014年 | 10958篇 |
2013年 | 18505篇 |
2012年 | 18952篇 |
2011年 | 21129篇 |
2010年 | 15040篇 |
2009年 | 15077篇 |
2008年 | 18056篇 |
2007年 | 17588篇 |
2006年 | 16605篇 |
2005年 | 14925篇 |
2004年 | 12130篇 |
2003年 | 10615篇 |
2002年 | 10107篇 |
2001年 | 10332篇 |
2000年 | 8522篇 |
1999年 | 7462篇 |
1998年 | 6459篇 |
1997年 | 6120篇 |
1996年 | 6251篇 |
1995年 | 5334篇 |
1994年 | 5374篇 |
1993年 | 4855篇 |
1992年 | 4902篇 |
1991年 | 4804篇 |
1990年 | 4340篇 |
1989年 | 3939篇 |
1988年 | 3634篇 |
1987年 | 3216篇 |
1986年 | 3209篇 |
1985年 | 3974篇 |
1984年 | 3914篇 |
1983年 | 3198篇 |
1982年 | 3414篇 |
1981年 | 3131篇 |
1979年 | 2998篇 |
1978年 | 3206篇 |
1977年 | 3208篇 |
1976年 | 3230篇 |
1975年 | 2984篇 |
1974年 | 3083篇 |
1973年 | 3114篇 |
排序方式: 共有10000条查询结果,搜索用时 790 毫秒
91.
Towards a Better Prediction of Cell Settling on Nanostructure Arrays—Simple Means to Complicated Ends
下载免费PDF全文
![点击此处可从《Advanced functional materials》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Nina Buch‐Månson Sara Bonde Jessica Bolinsson Trine Berthing Jesper Nygård Karen L. Martinez 《Advanced functional materials》2015,25(21):3246-3255
Vertical arrays of nanostructures (NSs) are emerging as promising platforms for probing and manipulating live mammalian cells. The broad range of applications requires different types of interfaces, but cell settling on NS arrays is not yet fully controlled and understood. Cells are both seen to deform completely into NS arrays and to stay suspended like tiny fakirs, which have hitherto been explained with differences in NS spacing or density. Here, a better understanding of this phenomenon is provided by using a model that takes into account the extreme membrane deformation needed for a cell to settle into a NS array. It is shown that, in addition to the NS density, cell settling depends strongly on the dimensions of the single NS, and that the settling can be predicted for a given NS array geometry. The predictive power of the model is confirmed by experiments and good agreement with cases from the literature. Furthermore, the influence of cell‐related parameters is evaluated theoretically and a generic method of tuning cell settling through surface coating is demonstrated experimentally. These findings allow a more rational design of NS arrays for the numerous exciting biological applications where the mode of cell settling is crucial. 相似文献
92.
93.
Lijuan Shen Li Li Sheng Lu Xiaohan Zhang Jie Liu Junlin An Guojun Zhang Bo Wu Fei Wang 《中国颗粒学报》2015,(3):10-15
We conducted measurements of black carbon(BC) aerosol in Jiaxing,China during autumn from September 26 to November 30,2013.We investigated temporal and diurnal variations of BC,and its correlations with meteorological parameters and other major pollutants.Results showed that hourly mass concentrations of BC ranged from 0.2 to 22.0 μg/m3,with an average of 5.1 μg/m3.The diurnai variation of BC exhibited a bimodal distribution,with peaks at 07:00 and 18:00.The morning peak was larger than the evening peak.The mass percentages of BC in PM2.5 and PM10 were 7.1%and 4.8%,respectively.The absorption coefficient of BC was calculated to be 44.4 Mm-1,which accounted for 11.1%of the total aerosol extinction.BC was mainly emitted from local sources in southwestern Jiaxing where BC concentrations were generally greater than 11 μg/m3 during the measurement period.Correlation analysis indicated that the main sources of BC were motor vehicle exhaust,and domestic and industrial combustion. 相似文献
94.
研究了受外场驱动的两个二能级系统分别与两个单模量子化光场相互作用模型中纠缠演化及转移问题。该工作主要是对外场驱动的Landau-Zener模型进行了研究,采用旋转波近似的方法,通过数值计算详细分析了二能级系统初始状态、能级间的耦合常数以及驱动外场的参数对子系统间纠缠和转移特性的影响。结果表明,适当调节模型中的参数,可以使系统初始纠缠完全转移为光腔场间的纠缠,实现二能级系统与光场间的最大纠缠转移。 相似文献
95.
JPC – Journal of Planar Chromatography – Modern TLC - A new high-performance thin-layer chromatographic (HPTLC) method has been developed for the simultaneous estimation of... 相似文献
96.
We consider conformal gravity as a gauge natural theory. We study its conservation laws and superpotentials. We also consider the Mannheim and Kazanas spherically symmetric vacuum solution and discuss conserved quantities associated to conformal and diffeomorphism symmetries. 相似文献
97.
98.
Hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) have been deemed as clean and sustainable strategies to solve the energy crisis and environmental problems. Various catalysts have been developed to promote the process of HER and OER. Among them, two-dimensional covalent organic frameworks (2D COFs) have received great attention due to their diverse and designable structure. In this minireview, we mainly summarize the diverse linkages of 2D COFs and strategies for enhancing the catalytic performance of 2D COFs for HER and OER, such as introducing active building blocks, metal ions and tailored linkages. Furthermore, a brief outlook for the development directions of COFs in the field of HER and OER is provided, expecting to stimulate new opportunities in future research. 相似文献
99.
Journal of Thermal Analysis and Calorimetry - In the present work, pyrolysis kinetic mechanism was studied for regenerated cellulosic fiber (RCF) and composite RCF containing silicon/nitrogen flame... 相似文献
100.
Natural products with a variety of pharmacological effects are important sources for commercial drugs, and it is very crucial to develop effective techniques to selectively extract and isolate bioactive natural components from the plants against the background of sustainable development. Ionic liquids (ILs) are a kind of designable material with unique physicochemical properties, including good thermal stability, negligible vapor pressure, good solvation ability, etc. ILs have already been used in pharmaceuticals for extraction, purification, drug delivery, etc. It has been reported that multi-interactions, like hydrogen bonding, hydrophobic interactions, play important roles in the extraction of bioactive components from the plants. In this review, recent progress in the understanding of scientific essence of hydrogen bonding, the special interaction, in ILs was summarized. The extraction of various natural products, one important area in pharmaceutical, by conventional and functional ILs as well as the specific roles of multi-interactions in this process were also reviewed. Moreover, problems existing in bioactive compound extraction by ILs and the future developing trends of this area are given, which might be helpful for scientists, especially beginners, in this field. 相似文献