全文获取类型
收费全文 | 9090篇 |
免费 | 368篇 |
国内免费 | 291篇 |
专业分类
化学 | 5336篇 |
晶体学 | 51篇 |
力学 | 246篇 |
综合类 | 18篇 |
数学 | 1960篇 |
物理学 | 2138篇 |
出版年
2022年 | 69篇 |
2021年 | 104篇 |
2020年 | 138篇 |
2019年 | 126篇 |
2018年 | 227篇 |
2017年 | 215篇 |
2016年 | 340篇 |
2015年 | 262篇 |
2014年 | 352篇 |
2013年 | 705篇 |
2012年 | 461篇 |
2011年 | 586篇 |
2010年 | 356篇 |
2009年 | 326篇 |
2008年 | 471篇 |
2007年 | 446篇 |
2006年 | 438篇 |
2005年 | 321篇 |
2004年 | 288篇 |
2003年 | 235篇 |
2002年 | 270篇 |
2001年 | 222篇 |
2000年 | 169篇 |
1999年 | 128篇 |
1998年 | 112篇 |
1997年 | 83篇 |
1996年 | 79篇 |
1995年 | 74篇 |
1994年 | 61篇 |
1993年 | 70篇 |
1992年 | 82篇 |
1991年 | 74篇 |
1990年 | 70篇 |
1989年 | 67篇 |
1988年 | 70篇 |
1987年 | 65篇 |
1986年 | 62篇 |
1985年 | 83篇 |
1984年 | 83篇 |
1983年 | 84篇 |
1982年 | 78篇 |
1981年 | 58篇 |
1980年 | 77篇 |
1979年 | 68篇 |
1978年 | 97篇 |
1977年 | 71篇 |
1976年 | 84篇 |
1975年 | 67篇 |
1974年 | 72篇 |
1973年 | 55篇 |
排序方式: 共有9749条查询结果,搜索用时 15 毫秒
91.
Dubravka Matković-Čalogović Zora Popović Branka Korpar-Čolig 《Journal of chemical crystallography》1995,25(8):453-458
[Hg(terpy)2](CF3SO3)2·0.5(CH3)2CO crystallizes in the triclinic
space group witha=14.631(6),b=15.258(4),c=18.785(7) Å, =69.66(2), =70.72(1), =88.55(1)°. The crystal structure consists of two independent [Hg(terpy)2]2+ cations, four trifluoromethanesulfonate anions and an acetone molecule in the asymmetric unit. Each mercury atom is coordinated by two tridentate terpyridine ligands forming an irregular six-coordination polyhedron. The Hg–N bond lengths range from 2.27(2) to 2.53(2) Å. 相似文献
92.
93.
N. Kallay M. Čolić D. W. Fuerstenau H. M. Jang E. Matijević 《Colloid and polymer science》1994,272(5):554-561
Potentiometric, electrokinetic, and coagulation experiments with a rutile dispersion in the pH region above the point of zero charge exhibit an inverse lyotropic sequence for counterions: Li+>K+>Cs+. The potentiometric and electrokinetic data were interpreted by a surface complexation model assuming the Stern-Gouy-Chapman structure of the interfacial layer, which yielded the values of inner layer capacitances,C, and the intrinsic equilibrium constants,K
ass
0
, characterizing the specificity of each counterion. These parameters were used to explain the order of lyotropic sequences in the adsorption, coagulation, and electrokinetic phenomena. 相似文献
94.
Miroslav Ploščica 《Algebra Universalis》1994,31(1):135-146
Presented by R. Freese. 相似文献
95.
A series ofc-axis oriented YBa2Cu3O
x
-films with different oxygen content were prepared by laser deposition. The oxygen contentx was determined by X-ray diffraction and by resonant Rutherford-back-scattering (RRBS) measurements. Thec-axis length in these films of YBa2Cu3O
x
is about 0.5% larger compared to bulk values. We describe transport measurements in magnetic fields up to 7 Tesla between room temperature andT
c
in samples with an oxygen content between the orthorhombic-to-tetragonal transition (x6.4) and full oxygenation (x7). The ratio /R
H
was investigated with respect to the two-dimensional Luttinger liquid theory and the model of the two-dimensional ionic metal. We report on deviations from the expected quadratic temperature behaviour of /R
H
, especially in films with high oxygen content. 相似文献
96.
Precise values of energies and widths of low-lying resonances in some rare-gas atom systems (Ar-Ar, Ne-Kr, Ne-Xe) are reported. 相似文献
97.
M. Ploščica 《Algebra Universalis》1996,35(2):249-255
We construct an example of a ternary structure satisfying certain conditions due to M. Kolibiar, which is not a betweenness relation of any lattice. This answers a question posed by J. Hedlíková and T. Katriák.Dedicated to the memory of Alan DayPresented by J. Sichler.Supported by GA SAV Grant 362/92. 相似文献
98.
An analytical scheme is proposed which combines three speciation techniques for determination of particular Al species in soil extracts and percolating waters. A cation-exchange fast protein liquid chromatography — inductively coupled plasma atomic emission spectrometry (FPLC-ICP-AES) procedure, a microcolumn chelating ion-exchange chromatography- atomic absorption spectrometry (MCC-ETAAS) technique and the 8-hydroxyquinoline spectrophotometric method (8HQ-spectrophotometry) were employed. The FPLC-ICP-AES procedure offers determination of Al3+ (retention time 4.5 min) and Al(OH)2+ species (retention time 4.0 min) which are separated from Al(OH)+
2 (retention time 1.5min). AlF2+ coelutes with Al(OH)2+ species, while Al(SO4)+, AlF+
2 and negatively charged Al organic complexes coelute with Al(OH)+
2 species. The MCC-ETAAS technique enables determination of the sum of positively charged monomeric aqua- and hydroxy-Al species plus sulphate- and fluoro-Al complexes. Employing the 8HQ-spectrophotometry the sum of positively charged monomeric aqua- and hydroxy-Al species plus sulphato- and most of the labile organic Al species are determined. The sensitivities of these selected techniques were adequate for speciation of Al in the samples analyzed. On the basis of the specific selectivity of a particular technique various groups of Al species may be determined. Thus, the comparison of analytical data from complementary procedures provides more comprehensive information on Al species present in soil extracts and percolating waters. 相似文献
99.
100.