全文获取类型
收费全文 | 1765篇 |
免费 | 44篇 |
国内免费 | 7篇 |
专业分类
化学 | 1389篇 |
晶体学 | 29篇 |
力学 | 20篇 |
数学 | 122篇 |
物理学 | 256篇 |
出版年
2021年 | 18篇 |
2019年 | 20篇 |
2018年 | 13篇 |
2017年 | 7篇 |
2016年 | 22篇 |
2015年 | 19篇 |
2014年 | 27篇 |
2013年 | 65篇 |
2012年 | 70篇 |
2011年 | 85篇 |
2010年 | 57篇 |
2009年 | 36篇 |
2008年 | 78篇 |
2007年 | 94篇 |
2006年 | 101篇 |
2005年 | 111篇 |
2004年 | 83篇 |
2003年 | 59篇 |
2002年 | 82篇 |
2001年 | 14篇 |
2000年 | 22篇 |
1999年 | 25篇 |
1998年 | 28篇 |
1997年 | 20篇 |
1996年 | 30篇 |
1995年 | 26篇 |
1994年 | 16篇 |
1993年 | 26篇 |
1992年 | 16篇 |
1991年 | 13篇 |
1990年 | 12篇 |
1989年 | 14篇 |
1988年 | 19篇 |
1987年 | 21篇 |
1986年 | 20篇 |
1985年 | 37篇 |
1984年 | 40篇 |
1983年 | 26篇 |
1982年 | 31篇 |
1981年 | 29篇 |
1980年 | 23篇 |
1979年 | 28篇 |
1978年 | 31篇 |
1977年 | 26篇 |
1976年 | 36篇 |
1975年 | 26篇 |
1974年 | 25篇 |
1973年 | 25篇 |
1972年 | 11篇 |
1971年 | 9篇 |
排序方式: 共有1816条查询结果,搜索用时 734 毫秒
111.
112.
The synthesis and crystal structure of NiMoO4·nH2O were investigated. The hydrate crystallized in the triclinic system with space group P−1, Z=4 with unit cell parameters of a=6.7791(2) Å, b=6.8900(2) Å, c=9.2486(2) Å, α=76.681(2)°, β=83.960(2)°, γ=74.218(2)°. Its ideal chemical composition was NiMoO4·3/4H2O rather than NiMoO4·1H2O. Under hydrothermal conditions the hydrate turned directly into α-NiMoO4 above 483 K, giving nanorods thinner than the crystallites of the mother hydrate. On the other hand, it turned into Anderson type of polyoxomolybdate via a solid-solution process in a molybdate solution at room temperature. 相似文献
113.
114.
Suzuki T Arai K Goto H Hanano M Watanabe J Tomono K 《Chemical & pharmaceutical bulletin》2002,50(6):741-743
Nifedipine-containing calcium phosphate cement (CPC) was prepared, and nifedipine (NF) release from this preparation was evaluated by the shaking method (SK), Japanese Pharmacopoeia XIV (JPXIV) paddle method (PD), and JPXIV flow-through cell method (FT). The release of NF from the CPC preparation continued for 7 d or longer by all these methods. This suggests that the release of NF can be controlled by preparing NF-containing CPC. The release pattern of NF from CPC in these tests was found to follow the Higuchi equation. However, the Higuchi constant differed among the three dissolution tests, probably because the apparent tortuosity of capillary system (tau) varied. 相似文献
115.
A new ent-kaurane diterpene glycoside, beta-D-glucopyranosyl 17-hydroxy-ent-kauran-19-oate-16-O-beta-D-glucopyranoside (4) was isolated from the dried leaves of Cussonia bojeri SEEM., together with four known compounds identified as 16beta,17-dihydroxy-kauran-19-oic acid (1), beta-D-glucopyranosyl 16beta,17-dihydroxy-(-)-kauran-19-oate (2), paniculoside IV (3), and rutin (5). The structure of 4 was deduced on the basis of chemical and spectroscopic evidence. 相似文献
116.
New phenylethanoid glycosides from Bacopa monniera 总被引:1,自引:0,他引:1
Chakravarty AK Sarkar T Nakane T Kawahara N Masuda K 《Chemical & pharmaceutical bulletin》2002,50(12):1616-1618
Three new phenylethanoid glycosides, viz. monnierasides I-III (1-3) along with the known analogue plantainoside B were isolated from the glycosidic fraction of Bacopa monniera. Their structures were elucidated mainly on the basis of two dimensional (2D) NMR spectral analyses. 相似文献
117.
Shinozuka K Matsumoto N Suzuki H Moriguchi T Sawai H 《Chemical communications (Cambridge, England)》2002,(22):2712-2713
A chimeric oligoDNA composed of a natural beta-anomeric oligonucleotide portion and an unnatural alpha-anomeric oligonucleotide portion forms an alternate stranded triplex possessing enhanced thermal stability compared to the triplexes composed of the parental oligomers. 相似文献
118.
[reaction: see text] A series of oligo(octithienylene-diethynylene)s alternately composed of octithiophene and diacetylene units have been prepared by a random Eglinton coupling reaction among mono- and diethynyloctithiophenes. The largest compound isolated in the oligomeric series is comprised of twelve octithiophene units and eleven diacetylene units, and its molecular length reaches ca. 43 nm, which is the longest among single-component conjugated nanomolecules. 相似文献
119.
Assuming naturalness that the quantum corrections to the mass should not exceed the order of the observed mass, we derive and apply model-independent bounds on the anomalous magnetic moments and electric dipole moments of leptons and quarks due to new physics. 相似文献
120.
Kazuo Kobayasi 《Proceedings of the American Mathematical Society》1999,127(4):1143-1150
We construct an inertial manifold for the evolution equation as a limit of the inertial manifolds for the difference approximations of the Trotter-Kato type and show that this limit is taken in a topology.