全文获取类型
收费全文 | 7335篇 |
免费 | 161篇 |
国内免费 | 37篇 |
专业分类
化学 | 4603篇 |
晶体学 | 73篇 |
力学 | 268篇 |
数学 | 1003篇 |
物理学 | 1586篇 |
出版年
2021年 | 82篇 |
2020年 | 111篇 |
2019年 | 112篇 |
2018年 | 160篇 |
2017年 | 169篇 |
2016年 | 198篇 |
2015年 | 98篇 |
2014年 | 173篇 |
2013年 | 320篇 |
2012年 | 263篇 |
2011年 | 287篇 |
2010年 | 244篇 |
2009年 | 276篇 |
2008年 | 266篇 |
2007年 | 274篇 |
2006年 | 230篇 |
2005年 | 199篇 |
2004年 | 195篇 |
2003年 | 192篇 |
2002年 | 208篇 |
2001年 | 154篇 |
2000年 | 124篇 |
1999年 | 73篇 |
1998年 | 71篇 |
1997年 | 68篇 |
1995年 | 108篇 |
1994年 | 125篇 |
1993年 | 101篇 |
1992年 | 96篇 |
1991年 | 103篇 |
1990年 | 110篇 |
1989年 | 90篇 |
1988年 | 77篇 |
1987年 | 100篇 |
1986年 | 92篇 |
1985年 | 124篇 |
1984年 | 150篇 |
1983年 | 90篇 |
1982年 | 113篇 |
1981年 | 95篇 |
1980年 | 84篇 |
1979年 | 141篇 |
1978年 | 127篇 |
1977年 | 124篇 |
1976年 | 134篇 |
1975年 | 102篇 |
1974年 | 67篇 |
1973年 | 94篇 |
1972年 | 69篇 |
1970年 | 72篇 |
排序方式: 共有7533条查询结果,搜索用时 296 毫秒
91.
An antiviral nucleoside or virazole was synthesized efficiently and regioselectively starting with benzyl cyanoformate. 相似文献
92.
93.
Solid solutions based on K3PO4 in systems K3 – 4x
E"
x
PO4 (E" = Si, Ti, Ge, Zr, Sn, Hf, Ce) are synthesized. The crystal structure, thermal behavior, and electroconduction of the synthesized solutions is studied. The narrowest single-phase regions take place in the systems where E" = Si, Ge (x 0.025), and the widest, in the system with Zr (x 0.125, at 700°C). Introducing Ti or Sn additives (x 0.05) and minimum quantities of Zr, Hf, or Ce (x = 0.025) into potassium orthophosphate leads to stabilization of highly-conductive -modification of K3PO4 at room temperature. Maximum values of potassium-cation conduction in all the systems studied correspond to regions of single-phase solid solutions based on K3PO4. The maximum electroconductivity (0.005 S cm–1 at 300°C, 0.1 S cm–1 at 700°C) and the smallest activation energies (32–35 kJ mol–1) take place in the systems with Zr and Hf. 相似文献
94.
Sal'keeva L. K. Nurmagambetova M. T. Kurmanaliev O. Sh. 《Russian Journal of General Chemistry》2002,72(12):1955-1955
Russian Journal of General Chemistry - 相似文献
95.
The liquid-liquid extraction, ion and precipitate flotation of Co(II) from chloride media of 1·10–4M initial Co(II) concentration and =0.1 have been investigated using decanoic acid and the results are compared. Organic solvents used were chloroform in the case of liquid-liquid extraction and ethanol (used as a solvent for the collector and a frother) in the case of flotation. From the results it appears that liquid-liquid extraction takes place through the formation of the complex: (CoR2)2(HR)2 but flotation occurs through the formation of a surface active product which has the empirical formula CoR2. The effects of pH and of decanoic acid concentration on the three separation processes were also investigated and the results discussed. Good agreement was observed between the experimental precipitate flotation curves and the theoretical curve calculated from the data published for Co(II) hydrolysis. 相似文献
96.
The first total synthesis of (+)?3-deoxyaphidicolin, a selective inhibitor of eukaryotic DNA polymerase α, has been completed efficiently and stereoselectively starting from 1-abietic acid. 相似文献
97.
A. A. Toropov V. O. Kudyshkin N. L. Voropaeva I. N. Ruban S. Sh. Rashidova 《Journal of Structural Chemistry》2004,45(6):945-950
For a series of monomers, QSPR test analysis is performed by optimizing the correlation weights of the local invariants of molecular graphs representing monomer structures in order to construct models of the reactivity parameters of monomers Q and e. This approach may be used as a tool in reactivity predictions for monomers for which no experimental data on Q and e are available.Original Russian Text Copyright © 2004 by A. A. Toropov, V. O. Kudyshkin, N. L. Voropaeva, I. N. Ruban, and S. Sh. Rashidova__________Translated from Zhurnal Strukturnoi Khimii, Vol. 45, No. 6, pp. 994–998, November–December, 2004. 相似文献
98.
99.
H. Sh. Bai H. X. Jin H. Q. Fan J. Du F. Wang D. M. Chen Zh. Cheng 《Journal of Radioanalytical and Nuclear Chemistry》1998,236(1-2):87-95
The behavior of153Sm-EDTMP in vitro and vivo is analyzed by the size exclusion HPLC. The experimental results show that EDTMP amounts have an
obvious effect on the stability in vitro and uptake of153Sm-EDTMP in the liver. HPLC analysis of urine sample indicates that153Sm-EDTMP es excreted in the original form. The behavior in vivo of153Sm-EDTMP containing 4 μg is similar to that of153Sm-EDTMP containing 50 μg EDTMP at 1 h post-injection. 相似文献
100.