全文获取类型
收费全文 | 1983篇 |
免费 | 497篇 |
国内免费 | 379篇 |
专业分类
化学 | 1556篇 |
晶体学 | 72篇 |
力学 | 121篇 |
综合类 | 13篇 |
数学 | 147篇 |
物理学 | 950篇 |
出版年
2024年 | 6篇 |
2023年 | 89篇 |
2022年 | 123篇 |
2021年 | 170篇 |
2020年 | 167篇 |
2019年 | 141篇 |
2018年 | 135篇 |
2017年 | 130篇 |
2016年 | 123篇 |
2015年 | 182篇 |
2014年 | 201篇 |
2013年 | 200篇 |
2012年 | 222篇 |
2011年 | 221篇 |
2010年 | 106篇 |
2009年 | 130篇 |
2008年 | 110篇 |
2007年 | 89篇 |
2006年 | 88篇 |
2005年 | 63篇 |
2004年 | 40篇 |
2003年 | 25篇 |
2002年 | 17篇 |
2001年 | 8篇 |
2000年 | 13篇 |
1999年 | 11篇 |
1998年 | 8篇 |
1997年 | 6篇 |
1996年 | 10篇 |
1995年 | 3篇 |
1994年 | 4篇 |
1993年 | 3篇 |
1992年 | 3篇 |
1991年 | 2篇 |
1990年 | 4篇 |
1989年 | 1篇 |
1987年 | 2篇 |
1985年 | 2篇 |
1936年 | 1篇 |
排序方式: 共有2859条查询结果,搜索用时 15 毫秒
1.
Interactions of the vector breathers for the coupled Hirota system with $$4\times 4$$ 4 × 4 Lax pair
Nonlinear Dynamics - In this paper, we investigate the interactions of the vector breathers for the coupled Hirota system with $$4\times 4$$ Lax pair. Firstly, we give the first-order breather... 相似文献
2.
Peng-Yan Gui Xiao-Hui Yan Wen-Juan Yuan Yuan-Liang Ma Xiao Ding Shuai Liu 《Natural product research》2019,33(19):2830-2836
A new A, D-seco limonoid, named 12-acetyloxyperforatin (1), along with three known ones, were isolated from the leaves of Harrisonia perforata. Their structures were elucidated on the basis of spectroscopic analysis, including extensive NMR techniques and computational modelling. These compounds showed no inhibitory activity against the 11β-HSD1 enzyme. 相似文献
3.
Application of Electron-Shelving Detection via 423 nm Transition in Calcium-Beam Optical Frequency Standard
下载免费PDF全文
![点击此处可从《中国物理快报》网站下载免费的PDF全文](/ch/ext_images/free.gif)
A new scheme of small compact optical frequency standard based on thermal calcium beam with application of 423 nm shelving detection and sharp-angle velocity selection detection is proposed. Combining these presented techniques, we conclude that a small compact optical frequency standard based on thermal calcium beam will outperform the commercial caesium-beam microwave dock, like the 5071 Cs clock (from Hp to Agilent, now Symmetricom company), both in accuracy and stability. 相似文献
4.
5.
A series of complexes formed between halogen-containing molecules and ammonia have been investigated by means of the atoms in molecules (AIM) approach to gain a deeper insight into halogen bonding. The existence of the halogen bond critical points (XBCP) and the values of the electron density (Pb) and Laplacian of electron density (V2pb) at the XBCP reveal the closed-shell interactions in these complexes. Integrated atomic properties such as charge, energy, polarization moment, volume of the halogen bond donor atoms, and the corresponding changes (△) upon complexation have been calculated. The present calculations have demonstrated that the halogen bond represents different AIM properties as compared to the well-documented hydrogen bond. Both the electron density and the Laplacian of electron density at the XBCP have been shown to correlate well with the interaction energy, which indicates that the topological parameters at the XBCP can be treated as a good measure of the halogen bond strength In addition, an excellent linear relationship between the interatomic distance d(X…N) and the logarithm of Pb has been established. 相似文献
6.
7.
8.
In this paper, we discuss the classical ill-posed problem of numerical differentiation, assuming that the smoothness of the function to be differentiated is unknown. Using recent results on adaptive regularization of general ill-posed problems, we propose new rules for the choice of the stepsize in the finite-difference methods, and for the regularization parameter choice in numerical differentiation regularized by the iterated Tikhonov method. These methods are shown to be effective for the differentiation of noisy functions, and the order-optimal convergence results for them are proved.
9.
用光谱技术研究了水溶液中氧氟沙星(OFLX)和左氟沙星(LVFX)与人血清白蛋白相互作用的机制.荧光猝灭法测得的结果表明反应的结合常数为KOFLX=0.482×105L@mol-1,KLVFX=0.529×105L@mol-1,结合位点数nOFLX=0.72,nLVFX=0.74.按照Fōorster非辐射能量转移理论得到药物-蛋白之间的结合距离分别为rOFLX=2.94nm,nVFX=2.85 nm.实验结果说明OFLX与LVFX在体内与蛋白结合直到运输到受体部位这一环节基本相同. 相似文献
10.
The synthesis and optical properties of tetrahedral fluorescent compounds comprising of tetraphenylmethane as the core and oligothiophenes as the chromophoric arms, and their water-soluble poly(ethylene glycol)-linked polymers are reported. 相似文献