全文获取类型
收费全文 | 2098篇 |
免费 | 247篇 |
国内免费 | 360篇 |
专业分类
化学 | 1111篇 |
晶体学 | 8篇 |
力学 | 26篇 |
综合类 | 20篇 |
数学 | 687篇 |
物理学 | 853篇 |
出版年
2023年 | 56篇 |
2022年 | 67篇 |
2021年 | 75篇 |
2020年 | 94篇 |
2019年 | 72篇 |
2018年 | 53篇 |
2017年 | 60篇 |
2016年 | 62篇 |
2015年 | 94篇 |
2014年 | 167篇 |
2013年 | 175篇 |
2012年 | 212篇 |
2011年 | 180篇 |
2010年 | 156篇 |
2009年 | 183篇 |
2008年 | 218篇 |
2007年 | 184篇 |
2006年 | 172篇 |
2005年 | 112篇 |
2004年 | 46篇 |
2003年 | 58篇 |
2002年 | 35篇 |
2001年 | 43篇 |
2000年 | 29篇 |
1999年 | 39篇 |
1998年 | 33篇 |
1997年 | 12篇 |
1996年 | 12篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1986年 | 1篇 |
1985年 | 3篇 |
排序方式: 共有2705条查询结果,搜索用时 31 毫秒
71.
72.
73.
Czechoslovak Mathematical Journal - Let G = (VG,EG) be a graph and let NG[υ] denote the closed neighbourhood of a vertex υ in G. A function f: VG ? {?1,0,1} is said to be a... 相似文献
74.
Acta Mathematicae Applicatae Sinica, English Series - A k-tree is a tree with maximum degree at most k. In this paper, we give a sharp degree sum condition for a graph to have a spanning k-tree in... 相似文献
75.
76.
Acta Mathematicae Applicatae Sinica, English Series - In this paper, we investigate a delayed HIV infection model that considers the homeostatic proliferation of CD4+ T cells. The existence and... 相似文献
77.
By variational methods, for a kind of Webster scalar curvature problems on the CR sphere with cylindrically symmetric curvature, we construct some multi-peak solutions as the parameter is sufficiently small under certain assumptions. We also obtain the asymptotic behaviors of the solutions. 相似文献
78.
《中国化学快报》2021,32(8):2359-2368
The photoisomerization properties of azo derivatives have been widely used in the fields of materials and biology.One serious restriction to the development of functional azo-based materials is the necessity to trigger switching by UV light,which damage the corresponding surfaces and penetrate only partially through the matter.Therefore,developing the visible and near-infrared light activated azo switches can solve this problem.This review provides a summary of molecular design strategies for driving the isomerization of azo derivatives with visible light and near-infrared light:(1) smart design directly excited by visible light,(2) the addition of upconversion nanoparticles,(3) the employment of twophoton absorption,(4) indirect excitation in combination with metal sensitizer. 相似文献
79.
80.
In this study, a porous polypropylene frit was coated with polydimethylsiloxane (PDMS) as extraction medium, based on the home-made PDMS-frit, a rapid, simple and sensitive sorptive extraction method was established for analysis of potential biomarkers of lung cancer (hexanal and heptanal) in human serum samples. In the method, derivatization and extraction occurred simultaneously on the PDMS-frit, then the loaded frit was ultrasonically desorbed in acetonitrile. Polymerization, derivatization–extraction and desorption conditions were optimized. Under the optimal conditions, satisfactory results were gained, a wide linear application range was obtained in the range of 0.002–5.0 μmol L−1 (R > 0.997) for two aldehydes, the detection limits (S N−1 = 3) were 0.5 nmol L−1 for hexanal and 0.4 nmol L−1 for heptanal. The relative standard deviations (RSDs, n = 5) of the method were below 7.9% and the recoveries were above 72.7% for the spiked serum. All these results hint that the proposed method is potential for disease markers analysis in complex biological samples. 相似文献