全文获取类型
收费全文 | 140781篇 |
免费 | 16155篇 |
国内免费 | 7991篇 |
专业分类
化学 | 100916篇 |
晶体学 | 1786篇 |
力学 | 6529篇 |
综合类 | 566篇 |
数学 | 15021篇 |
物理学 | 40109篇 |
出版年
2023年 | 934篇 |
2022年 | 1866篇 |
2021年 | 2501篇 |
2020年 | 3791篇 |
2019年 | 5168篇 |
2018年 | 4113篇 |
2017年 | 3794篇 |
2016年 | 7026篇 |
2015年 | 6102篇 |
2014年 | 7130篇 |
2013年 | 9370篇 |
2012年 | 8643篇 |
2011年 | 8373篇 |
2010年 | 7576篇 |
2009年 | 7592篇 |
2008年 | 7371篇 |
2007年 | 6497篇 |
2006年 | 5858篇 |
2005年 | 5500篇 |
2004年 | 4806篇 |
2003年 | 4330篇 |
2002年 | 5166篇 |
2001年 | 4165篇 |
2000年 | 3540篇 |
1999年 | 2213篇 |
1998年 | 1742篇 |
1997年 | 1513篇 |
1996年 | 1447篇 |
1995年 | 1205篇 |
1994年 | 1268篇 |
1993年 | 1191篇 |
1992年 | 1128篇 |
1991年 | 1171篇 |
1990年 | 1160篇 |
1989年 | 1073篇 |
1988年 | 939篇 |
1987年 | 937篇 |
1986年 | 904篇 |
1985年 | 940篇 |
1984年 | 923篇 |
1983年 | 831篇 |
1982年 | 805篇 |
1979年 | 803篇 |
1978年 | 812篇 |
1977年 | 808篇 |
1976年 | 919篇 |
1975年 | 815篇 |
1974年 | 846篇 |
1973年 | 851篇 |
1972年 | 753篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
911.
C.X. Gao F.C. Yu S.Y. Jeong A.R. Choi P. Parchinskiy D.J. Kim H.J. Kim Y.E. Ihm C.G. Kim C.S. Kim 《Journal of magnetism and magnetic materials》2006
GaMnN and Be-codoped GaMnN were grown via molecular beam epitaxy using a single GaN precursor and their structural and magnetic properties were examined. X-ray diffraction and superconducting quantum interference device (SQUID) measurements revealed that the grown layers are homogeneous without precipitates. The saturation magnetization of GaMnN has increased from ∼4 to ∼16 emu/cm3 via codoping of Be. The d–d exchange interaction between Mn atoms was discussed for the ferromagnetism of GaMnN. 相似文献
912.
In this paper, experimental results of the investigation of the periodic structure on thermoelectric semiconductor Cu2Se are presented. Periodic structures were formed on surfaces of semiconductors due to multi-beam interaction of Q-switched Nd:YAG laser, which was operated in the lowest order of Gaussian mode and pulse duration 7 ns. Surface temperature evolution and transient reflectivity are studied during laser treatment. Creation of Cu islands in the maximal intensity of interference pattern was found. 相似文献
913.
Dmitry Yu. Murzin 《Reaction Kinetics and Catalysis Letters》2007,90(2):225-232
Reaction route analysis is applied to visualize reaction networks in several heterogeneous catalytic reactions. Combination
of the theory of complex reactions with the notion of catalytic cycles results in a topological representation of complex
mechanisms with the nodes comprising all possible surface species including free sites and branches indicating interconnections
between reactions. 相似文献
914.
Yu. A. Dobrovolsky P. Jannasch B. Lafitte N. M. Belomoina A. L. Rusanov D. Yu. Likhachev 《Russian Journal of Electrochemistry》2007,43(5):489-501
The 2000–2006 achievements in the field of synthesis, property examination, and application of proton-exchange membranes are reviewed on the basis of more than 120 papers. 相似文献
915.
The theory of asymptotic speeds of spread and monotone traveling waves is established for a class of monotone discrete and continuous‐time semiflows and is applied to a functional differential equation with diffusion, a time‐delayed lattice population model and a reaction‐diffusion equation in an infinite cylinder. © 2005 Wiley Periodicals, Inc. 相似文献
916.
Recently, we have developed a new tight-binding quantum chemical molecular dynamics program “Colors” for combinatorial computational chemistry approach. This methodology is based on our original tight-binding approximation and realized over 5000 times acceleration compared to the conventional first-principles molecular dynamics method. In the present study, we applied our new program to the simulations on various realistic large-scale models of the automotive three-way catalysts, ultrafine Pt particle/CeO2(111) support. Significant electron transfer from the Pt particle to the CeO2(111) surface was observed and it was found to strongly depend on the size of the Pt particle. Furthermore, our simulation results suggest that the reduction of the Ce atom due to the electron transfer from the Pt particle to the CeO2 surface is a main reason for the strong interaction of the Pt particle and CeO2(111) support. 相似文献
917.
Electroluminescence of a Multi-Layered Organic Light-Emitting Diode Utilizing Trans-4-[p-[N-methyl-N-(hydroxymethyl)amino]styryl]-N-Methylphridinium Tetraphenylborate as the Active Layer
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)
Employing an organic dye salt of trans-4-[p-[N-methyl-N-(hydroxymethyl)amino]styryl]-N-methylphridinium tetra\-phenylborate (ASPT) as the active layer, 8-hydrocyquinoline aluminium (Alq3) as the electron transporting layer and N,N’-diphenyl-N,N’-bis(3-methylphenyl)-[1,1’-biphenyl]-4,4’-diamine (TPD) as the hole transporting layer, respectively, we fabricate a multi-layered organic light-emitting diode and observe the colour tunable electroluminescence (EL). The dependence of the EL spectra on the applied voltage is investigated in detail, and the recombination mechanism is discussed by considering the variation of the hole-electron recombination region. 相似文献
918.
A. P. Menushenkov S. Yu. Mukhalov B. I. Sevast'yanov 《Mechanics of Composite Materials》1989,24(5):659-662
Conclusions These tests on quasistationary irradiated for polyethylene-matrix powder-filled composites show that the filler composition and content have marked effects on the damage.There are ranges where the specific loss, the pressure, and the integral recoil pulse decrease as the power density increases because of changes in the damage mechanism, which are most prominent for zirconium oxide as filler. Bulk absorption contributes considerably, and causes various types of defect. Estimates have been made of the pressures arising in explosive matrix decomposition in the bulk together with the specific damage energies.These measurements are useful in modeling laser effects on composites.Translated from Mekhanika Kompositnykh Materialov, No. 5, pp. 868–872, September–October, 1988. 相似文献
919.
Yan Shun MA Qing Hua MENG Hong Yu SHI Yuan De LONG Tian Bao HUANG 《中国化学快报》2006,17(6):807-808
Dencichine (β-N-oxalyl-L-α, β-diaminopropionic acid, L-ODAP), a nonprotein amino acid, is a haemostatic agent present in important Chinese medicinal herbs such as Panax notoginseng, as well as other Panax species1. It was first isolated from the seeds … 相似文献
920.
The constitutive behavior of porous materials (including the yield loci, the void growth rate, the macro stress-strain relation
and the strain to localization instability) is examined based on the lower bound approach proposed by the present authors.
These results are then compared with the experimental and the finite element results as well as those predicted by Gurson's
equations. Emphasis is placed on approaching the real behavior from the upper and the lower bound analysis. Calculation is
also made on the influence of void nucleation on the critical strain to instability and a modified strain-controlled nucleation
criterion is proposed. Finally the instability and fracture of AISI4340 steel in plane strain tension is examined and comparison
is made between theoretical and experimental results. 相似文献