全文获取类型
收费全文 | 5947篇 |
免费 | 1249篇 |
国内免费 | 2568篇 |
专业分类
化学 | 4832篇 |
晶体学 | 198篇 |
力学 | 419篇 |
综合类 | 207篇 |
数学 | 946篇 |
物理学 | 3162篇 |
出版年
2024年 | 8篇 |
2023年 | 66篇 |
2022年 | 219篇 |
2021年 | 210篇 |
2020年 | 195篇 |
2019年 | 202篇 |
2018年 | 187篇 |
2017年 | 288篇 |
2016年 | 213篇 |
2015年 | 277篇 |
2014年 | 368篇 |
2013年 | 476篇 |
2012年 | 469篇 |
2011年 | 479篇 |
2010年 | 455篇 |
2009年 | 563篇 |
2008年 | 570篇 |
2007年 | 518篇 |
2006年 | 553篇 |
2005年 | 469篇 |
2004年 | 378篇 |
2003年 | 230篇 |
2002年 | 295篇 |
2001年 | 298篇 |
2000年 | 350篇 |
1999年 | 269篇 |
1998年 | 145篇 |
1997年 | 121篇 |
1996年 | 100篇 |
1995年 | 84篇 |
1994年 | 75篇 |
1993年 | 72篇 |
1992年 | 72篇 |
1991年 | 53篇 |
1990年 | 62篇 |
1989年 | 62篇 |
1988年 | 46篇 |
1987年 | 47篇 |
1986年 | 43篇 |
1985年 | 36篇 |
1984年 | 36篇 |
1983年 | 32篇 |
1982年 | 17篇 |
1981年 | 16篇 |
1980年 | 12篇 |
1979年 | 10篇 |
1978年 | 5篇 |
1976年 | 2篇 |
1954年 | 1篇 |
1936年 | 3篇 |
排序方式: 共有9764条查询结果,搜索用时 0 毫秒
41.
应用超球会标表示氦原子和氢负离子的薛定谔方程,将二电子原子在三维空间中的运动转化为单电子原子在六维空间中受广义库仑力作用的运动,我们给出了六维空间广义角动量算符的本征值与本征函数,并以此本征函数微基构造超球波函数,得到超球径微分方程,以广义Laguerre 多项式表示超球径波函数,运用密度矩阵和线性变分法得到非正交基下超球径波函数满足的久期方程,最后求得能量和波函数,计算结果与精确的计算符合良好。 相似文献
42.
43.
光同时诱导水中Cr(Ⅵ)的还原与橙黄Ⅱ的氧化;染料;橙黄Ⅱ;Cr(Ⅵ);光还原;光降解 相似文献
44.
Lingyan Zhang Ruo Yuan Xiaoqing Huang Yaqing Chai Shurui Cao 《Electrochemistry communications》2004,6(12):1222-1226
A novel potentiometric immunosensor for detection of Japanese B encephalitis vaccine was developed by immobilizing antiserum of Japanese B encephalitis on nano-Au/polymerized o-phenylenediamine (o-PDA) film on the platinum (Pt) electrode. The performance and factors influencing the performance of the resulting immunosensor were studied. The immunosensor showed a specific response to Japanese B encephalitis vaccine in the range 1.1 × 10−8 to 2.0 × 10−6 lgpfu/ml (plaque forming unit) with a detection limit of 6 × 10−9 lgpfu/ml. The correlation coefficient is 0.9986. The incubation time, incubation temperature, pH, reproducibility and stability of the immunosensor were also studied. The present work supplied a promising test method for biological products. 相似文献
45.
锂离子电池正极材料LiMn2O4的合成与晶体结构(英) 总被引:2,自引:0,他引:2
Spinel LiMn2O4 powders were prepared using two-step synthesis method consisting of solid-state reaction method and citrate modified sol-gel method. The effects of the calcination temperature and the Li/Mn ratio of raw materials were studied on the physicochemical and electrochemical properties of the spinel LiMn2O4 powders, such as crystallinity, lattice constant and density. The title compound was characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Polycrystalline LiMn2O4 powers calcined at 750 ℃ were found to be composed of very uniformly-sized microcrystal with an average particle size of 300 nm. The improvement in electrochemical properties was mainly attributed to the process of re-grinding by absolute alcohol. 相似文献
47.
48.
Initiation mechanism of the photopolymerization of acrylonitrile and methyl methacrylate, usingbinary condensed aromatic hydrocarbon (CAH)-aniline systems as initiator, was studied. The strongerthe electron-donating ability of the aniline derivatives, the faster the the of photopolymerizationwill be. The radical intermediates produced by photoreaction between anthracene and anilinewere detected with ESR spectra. The initiation scheme involves the formation of exciplex betweenthe excited singlet state of CAH and the ground state of aniline as the first step, and then followedby proton transfer, leading to the generation of two kinds of radicals. From the end-group analysisof the polymers obtained, it is suggested that both kinds of radicals are involved in the initiation. 相似文献
49.
FENG Yu-Ling SUN Jing-Guo 《有机化学》2003,23(Z1):47-48
Clarithromycin, 6- O-methylerythromycin A (CAM), is a semisynthetic macrolide antibiotic of 6 which exhibits strong antibacterial activity toward a wide range of bacteria inclusive of gram positive bacteria, some gram negative bacteria, anaerobic bacteria, Mycoplasma, Chlamidia and Helicobacter pylori, and because of its high stability in the acidic environment of the stomach, it can be orally administered to treat respiratory organ diseases, and also to prevent recurrence of ulcer when used in a combination with other medicines. 相似文献
50.
Classical antifolates containing L-glutamic acid moiety in molecule have shortcomings such as drug resistance which is originated from the defective cell transport by mutation, and toxicity to the host which is due to unnecessarily long retention inside normal cells.[1] One strategy to overcome these shortcomings is to design nonclassical lipophilic inhibitors of folate requiring enzymes by deleting or modifying L-glutamic acid component from the folate analogues. 相似文献