全文获取类型
收费全文 | 20312篇 |
免费 | 2897篇 |
国内免费 | 4238篇 |
专业分类
化学 | 14515篇 |
晶体学 | 531篇 |
力学 | 1082篇 |
综合类 | 402篇 |
数学 | 2592篇 |
物理学 | 8325篇 |
出版年
2023年 | 208篇 |
2022年 | 418篇 |
2021年 | 474篇 |
2020年 | 546篇 |
2019年 | 527篇 |
2018年 | 466篇 |
2017年 | 579篇 |
2016年 | 665篇 |
2015年 | 773篇 |
2014年 | 919篇 |
2013年 | 1319篇 |
2012年 | 1463篇 |
2011年 | 1716篇 |
2010年 | 1349篇 |
2009年 | 1480篇 |
2008年 | 1666篇 |
2007年 | 1492篇 |
2006年 | 1480篇 |
2005年 | 1313篇 |
2004年 | 1100篇 |
2003年 | 874篇 |
2002年 | 835篇 |
2001年 | 815篇 |
2000年 | 794篇 |
1999年 | 479篇 |
1998年 | 327篇 |
1997年 | 268篇 |
1996年 | 283篇 |
1995年 | 243篇 |
1994年 | 256篇 |
1993年 | 234篇 |
1992年 | 225篇 |
1991年 | 166篇 |
1990年 | 198篇 |
1989年 | 149篇 |
1988年 | 141篇 |
1987年 | 119篇 |
1986年 | 115篇 |
1985年 | 128篇 |
1984年 | 100篇 |
1983年 | 94篇 |
1982年 | 63篇 |
1981年 | 64篇 |
1980年 | 63篇 |
1979年 | 52篇 |
1978年 | 44篇 |
1977年 | 40篇 |
1976年 | 38篇 |
1974年 | 50篇 |
1973年 | 45篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
991.
992.
Lee Chang Hwa Kim Tack-Jin Yoon Dalsung Jang Junhyuk Kim Gha-Young Lee Sung-Jai 《Journal of Radioanalytical and Nuclear Chemistry》2019,322(2):331-336
Journal of Radioanalytical and Nuclear Chemistry - U chlorination is demonstrated using electrochemical and chemical reactions with ZnCl2 in LiCl–KCl molten salts. Voltammetric studies... 相似文献
993.
994.
A. L. Pirozerskii E. V. Charnaya M. K. Lee L. J. Chang A. I. Nedbai Yu. A. Kumzerov A. V. Fokin M. I. Samoilovich E. L. Lebedeva A. S. Bugaev 《Acoustical Physics》2016,62(3):306-312
The paper presents the results of studying the crystallization and melting processes of Ga–In eutectic alloys, which are embedded in opal matrices, using acoustic and NMR methods. The indium concentrations in the alloys were 4, 6, 9, and 15 at %. Measurements were performed upon cooling from room temperature to complete crystallization of the alloys and subsequent heating. It is revealed how the size effects and alloy composition influence the formation of phases with α- and β-Ga structures and on changes in the melting-temperature ranges. A difference was observed between the results obtained using acoustic and NMR methods, which was attributed to different temperature measurement conditions. 相似文献
995.
Depending on different reaction time and temperature employed, benzylation of 2,3-dichloronaphthazarin (I) using silver oxide as the catalyst can form either exclusively 5,8-dibenzyloxy-6,7-dichloronaphthalene-1,4-dione (II), or exclusively 5-benzyloxy-2,3-dichloro-8-hydroxynaphthalene-1,4-dione (IV); or a mixture of II and 5,8-dibenzyloxy-2,3-dichloronaphthalene-1,4-dione (III). Structures of these compounds were identified by nmr analysis. 相似文献
996.
�� ������ �ƣ�¬ ������ �أ�������� ���������� 《核聚变与等离子体物理》2017,37(4):418-421
The power measurement method for 3.7GHz LHCD system on HL-2A was introduced. It is found by HFSS simulation that the impact of backward wave phase on the measurement of forward power may be suppressed if the isolation of directional coupler is more than 30dB. After improving the system, the total transmission line efficiency of the LHCD system can reach 89% with maximum power 1.5MW in 2016 experiment campaign. 相似文献
997.
Chang Hyeong Lee Kyung Duk Park Bongsoo Jang 《Journal of mathematical chemistry》2013,51(7):1945-1960
In this paper, we present the multistage homotopy perturbation method for finding the solution of the chemical kinetics with nonlinear reactions. We develop a general scheme for finding the analytic solution of chemical reaction networks and apply it to motivating chemical examples such as the enzyme kinetics model and the Brusselator model. We illustrate the numerical result for the models and show the accuracy of the method. 相似文献
998.
Optical Review - We experimentally realized and demonstrated a solid-state, passively Q-switched Nd:YVO4/PPLN green laser with a saturable absorber (SA) based on few-layered MoS2. The MoS2 SA was... 相似文献
999.
Chang Ling Chang Shuquan Han Wei Li Zheng Zhang Zheng Dai Yaodong Zhang Haiqian 《Journal of Radioanalytical and Nuclear Chemistry》2017,311(1):289-299
Journal of Radioanalytical and Nuclear Chemistry - The present paper, for the first time, reports the application of Ba2TiSi2O8 (BTS) for management of trivalent actinides present in radioactive... 相似文献
1000.
Fluorescence imaging in the second near-infrared region(900-1700 nm, NIR-II) with a high resolution and penetration depth due to the significantly reduced tissue scattering and autofluorescence has emerged as a useful tool in biomedical fields. Recently, many efforts have been devoted to the development of fluorophores with an emission band covering the long-wavelength end of NIR-II region(1500-1700 nm) to eliminate the autofluorescence. Alternatively, we believe imaging with a narrow bandwidth could also reduce the autofluorescence. As a proof of concept, NaYF4:Yb,Nd@NaYF4 downconversion nanoparticles(DCNPs) with sharp NIR-II emission were synthesized. The luminescence of DCNPs showed a half-peak width of 49 nm centered at 998 nm, which was perfectly matched with a (1000±25) nm bandpass filter. With this filter, we were able to retain most of the emissions from the nanoparticles, while the autofluorescence was largely reduced. After PEGylation, the DCNPs exhibited great performance for blood vessel and tumor imaging in living mice with significantly reduced autofluorescence and interference signals. This work provided an alternative way for the low-autofluorescence imaging and emphasized the importance of narrow emitting rare-earth doped nanoparticles for NIR-II imaging. 相似文献