全文获取类型
收费全文 | 71671篇 |
免费 | 7645篇 |
国内免费 | 4733篇 |
专业分类
化学 | 41297篇 |
晶体学 | 770篇 |
力学 | 3905篇 |
综合类 | 214篇 |
数学 | 13547篇 |
物理学 | 24316篇 |
出版年
2024年 | 119篇 |
2023年 | 936篇 |
2022年 | 1439篇 |
2021年 | 1722篇 |
2020年 | 1968篇 |
2019年 | 1867篇 |
2018年 | 2746篇 |
2017年 | 2788篇 |
2016年 | 2836篇 |
2015年 | 2603篇 |
2014年 | 2982篇 |
2013年 | 3918篇 |
2012年 | 7006篇 |
2011年 | 6265篇 |
2010年 | 4397篇 |
2009年 | 4061篇 |
2008年 | 3395篇 |
2007年 | 3087篇 |
2006年 | 2899篇 |
2005年 | 6285篇 |
2004年 | 5313篇 |
2003年 | 3401篇 |
2002年 | 1600篇 |
2001年 | 1176篇 |
2000年 | 835篇 |
1999年 | 1031篇 |
1998年 | 801篇 |
1997年 | 710篇 |
1996年 | 725篇 |
1995年 | 622篇 |
1994年 | 514篇 |
1993年 | 423篇 |
1992年 | 548篇 |
1991年 | 459篇 |
1990年 | 421篇 |
1989年 | 324篇 |
1988年 | 251篇 |
1987年 | 180篇 |
1986年 | 185篇 |
1985年 | 149篇 |
1984年 | 99篇 |
1983年 | 87篇 |
1982年 | 61篇 |
1981年 | 60篇 |
1976年 | 90篇 |
1975年 | 49篇 |
1974年 | 42篇 |
1973年 | 50篇 |
1972年 | 44篇 |
1969年 | 42篇 |
排序方式: 共有10000条查询结果,搜索用时 703 毫秒
41.
Effect of the dispersion on multipartite continuous-variable entanglement in optical parametric amplifier
下载免费PDF全文
![点击此处可从《中国物理 B》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Based on the quantum fluctuations, we adopt the method of generalized V1 criterion to investigate multipartite entanglement characteristics in an optical parametric amplification system with the consideration of dispersion. The nonlinear interaction becomes strong because of the existence of dispersion coefficient σ. Considering the influence of dispersion factor σ, with increasing the pump parameter μ, the value of minimum variance V1 decreases and the squeezing curve nearly equals 1/(1 + μ). The larger particle number N results in a smaller variance and higher entanglement. 相似文献
42.
Liming Fan Feng Wang Dongsheng Zhao Yuxin Peng Yuxin Deng Yinwei Luo Xiutang Zhang 《应用有机金属化学》2020,34(12):e5960
Guided by the self-penetrating features can improve the stability of metal organic frameworks (MOFs), an unprecedented 3D self-penetrated framework, {[Zn (tptc)0.5(bimb)]·H2O}n ( NUC-6 , here NUC corresponding to North University of China), with 3D (4,4)-c {86} net, was designed. Benefit from the high chemical stability and excellent luminescent property, NUC-6 can be act as an efficient multi-response chemo-sensor in detecting dichloronitroaniline pesticide and nitrofuran antibiotics in water with the detection limits are 116 ppb for DCN pesticide, 16 ppb for NFT antibiotic, and 12 ppb for NTZ antibiotic. Besides, the mechanisms of luminescence quenching were revealed from the viewpoint of internal filter effect (IFE) and photo-induced electron transfer (PET), implied by the optical spectroscopy and quantum chemical calculation. This work provides a promising strategy to design stable MOFs by improving the self-penetrating features and to expand their practical applications in the detection of organic pollutants in aqueous medium. 相似文献
43.
Sha Xia Dan Wang Nian-Ke Chen Dong Han Xian-Bin Li Hong-Bo Sun 《Annalen der Physik》2020,532(3):1900318
Defects play a central role in controlling the electronic properties of two-dimensional (2D) materials and realizing the industrialization of 2D electronics. However, the evaluation of charged defects in 2D materials within first-principles calculation is very challenging and has triggered a recent development of the WLZ (Wang, Li, Zhang) extrapolation method. This method lays the foundation of the theoretical evaluation of energies of charged defects in 2D materials within the first-principles framework. Herein, the vital role of defects for advancing 2D electronics is discussed, followed by an introduction of the fundamentals of the WLZ extrapolation method. The ionization energies (IEs) obtained by this method for defects in various 2D semiconductors are then reviewed and summarized. Finally, the unique defect physics in 2D dimensions including the dielectric environment effects, defect ionization process, and carrier transport mechanism captured with the WLZ extrapolation method are presented. As an efficient and reasonable evaluation of charged defects in 2D materials for nanoelectronics and other emerging applications, this work can be of benefit to the community. 相似文献
44.
Aequationes mathematicae - We discuss equivalence conditions for the non-existence of non-trivial meromorphic solutions to the Fermat Diophantine equation $$f^m(z)+g^n(z)=1$$ with integers $$m,n\ge... 相似文献
45.
46.
47.
Shi-Tao Han Hong-Ying Duan Lan-Yun Chen Dr. Tian-Guang Zhan Dr. Li-Juan Liu Li-Chun Kong Prof. Kang-Da Zhang 《化学:亚洲杂志》2021,16(23):3886-3889
A photo-switchable hetero-complementary quadruple H-bonding array, which consists of an azobenzene-derived ureidopyrimidinone (UPy) module ( Azo-UPy ) and a nonphotoactive diamidonaphthyridine (DAN) derivative ( Napy-1 ), is constructed based on a reversible photo-locking approach. Upon UV (390 nm)/Vis (460 nm) light irradiations, photo-switchable quadruple H-bonded dimerization between Azo-UPy and Napy-1 can be achieved with exhibiting 4.8×104-fold differences in binding strength (ON/OFF ratios). Furthermore, smart polymeric gels with unique photo-controlled macroscopic self-assembly behavior can be fabricated by introducing such quadruple H-bonding array as photo-regulable noncovalent interfacial connections. 相似文献
48.
49.
50.
Kinetics and Catalysis - A series of Cu-SSZ-13@CeO2 catalysts with surface modification with CeO2 was prepared by the modified self-resemble method based on the one-pot synthesized Cu-SSZ-13... 相似文献