全文获取类型
收费全文 | 7567篇 |
免费 | 275篇 |
国内免费 | 55篇 |
专业分类
化学 | 5144篇 |
晶体学 | 58篇 |
力学 | 134篇 |
数学 | 1202篇 |
物理学 | 1359篇 |
出版年
2023年 | 42篇 |
2022年 | 156篇 |
2021年 | 177篇 |
2020年 | 175篇 |
2019年 | 177篇 |
2018年 | 161篇 |
2017年 | 117篇 |
2016年 | 278篇 |
2015年 | 237篇 |
2014年 | 277篇 |
2013年 | 472篇 |
2012年 | 508篇 |
2011年 | 599篇 |
2010年 | 333篇 |
2009年 | 306篇 |
2008年 | 455篇 |
2007年 | 432篇 |
2006年 | 398篇 |
2005年 | 340篇 |
2004年 | 271篇 |
2003年 | 232篇 |
2002年 | 218篇 |
2001年 | 87篇 |
2000年 | 104篇 |
1999年 | 68篇 |
1998年 | 47篇 |
1997年 | 62篇 |
1996年 | 100篇 |
1995年 | 78篇 |
1994年 | 47篇 |
1993年 | 54篇 |
1992年 | 62篇 |
1991年 | 45篇 |
1990年 | 44篇 |
1989年 | 33篇 |
1988年 | 43篇 |
1987年 | 28篇 |
1986年 | 29篇 |
1985年 | 45篇 |
1984年 | 46篇 |
1983年 | 35篇 |
1982年 | 48篇 |
1981年 | 41篇 |
1980年 | 42篇 |
1979年 | 34篇 |
1978年 | 47篇 |
1977年 | 34篇 |
1976年 | 22篇 |
1975年 | 22篇 |
1973年 | 20篇 |
排序方式: 共有7897条查询结果,搜索用时 15 毫秒
31.
32.
H. Eduardo Roman 《Journal of statistical physics》1990,58(1-2):375-382
Extensive Monte Carlo simulations of theant-in-the-labyrinth problem on randomL* L* L simple cubic lattices are performed, forL up to 960 on a CRAY-YMP supercomputer. The exponentk for the rms displacementr witht inrt
k
is found to bek=0.190±0.003. As a second approach, large percolation clusters with chemical shells up to 300 are generated on a simple cubic lattice at criticality. The diffusion equation is then solved by using the exact enumeration technique. The corresponding critical exponentd
w
is found to be 1/d
w
=0.250±0.003.On leave from I. Institut für Theoretische für Physik, Universität Hamburg, D-2000 Hamburg, Federal Republic of Germany. 相似文献
33.
Roman Murawski 《Archive for Mathematical Logic》1988,27(1):21-33
We consider expansions of models of Peano arithmetic to models ofA
2
s
-¦
1
1
+
1
1
–AC which consist of families of sets definable by nonstandard formulas. 相似文献
34.
35.
Shkumbatiuk R Bazel YR Andruch V Török M 《Analytical and bioanalytical chemistry》2005,382(6):1431-1437
A new, simple, rapid, and sensitive spectrophotometric method has been developed for the determination of nitrophenols [picric acid (PA); dinitrophenols (DNP)] in wastewater samples. The method is based on the reaction of nitrophenols with 2-[(E)-2-(4-diethylaminophenyl)-1-ethenyl]-1,3,3-trimethyl-3 H-indolium chloride reagent to form the colored ion associates, which are extracted by organic solvents. The molar absorptivity of the ion associates of PA with the investigated reagent ranges from 8.3×104 to 11.3×104 L mol–1 cm–1, depending on the extractant. Because only PA is extracted in an acidic medium with the investigated reagent, but both PA and DNP are extracted in an alkaline medium, it is possible to determine both substances in a mixture. Appropriate reaction conditions have been established. The absorbance of the colored extracts obeys Beers law in the range of 0.04–4.58 mg L–1 PA, 1.0–18.4 mg L–1 2,4-DNP and 1.2–14.7 mg L–1 2,6-DNP, respectively. The limit of detections, calculated from a blank test (n=10; P=0.95), are 0.05 mg L–1 PA, 0.9 mg L–1 (2,4-DNP), and 1.1 mg L–1 (2,6-DNP), respectively. 相似文献
36.
37.
Episulfidation of (E)-cyclooctene and (E)-cyclononene was achieved with elemental sulfur by using a catalytic amount of a molybdenum oxo complex. 相似文献
38.
39.
Bombek S Lenarsic R Kocevar M Saint-Jalmes L Desmurs JR Polanc S 《Chemical communications (Cambridge, England)》2002,(14):1494-1495
An electrophilic amination of halogenated phenols with diisopropyl diazenedicarboxylate in the presence of ZrCl4 as a Lewis acid, accompanied by a halogen migration, was demonstrated for the first time; the fluorine, chlorine, bromine, or iodine atom migrated during the amination process under mild reaction conditions. 相似文献
40.
Some new stabilisers having a chelating polymeric structure were synthesised and characterised, i.e., 8-hydroxyquinoline-formaldehyde chelating resins of Cd, Zn, and Pb. The efficiency of these new stabilisers was studied with respect to PVC. The stabilised PVC samples showed outstanding thermal stability as studied by thermogravimetric techniques, i.e., the percentage of HCl evolved reduced remarkably with increasing polymer decomposition temperature. 相似文献