全文获取类型
收费全文 | 4497篇 |
免费 | 120篇 |
国内免费 | 7篇 |
专业分类
化学 | 2894篇 |
晶体学 | 57篇 |
力学 | 65篇 |
数学 | 478篇 |
物理学 | 1130篇 |
出版年
2021年 | 37篇 |
2020年 | 40篇 |
2019年 | 47篇 |
2018年 | 29篇 |
2016年 | 69篇 |
2015年 | 69篇 |
2014年 | 78篇 |
2013年 | 146篇 |
2012年 | 156篇 |
2011年 | 182篇 |
2010年 | 123篇 |
2009年 | 90篇 |
2008年 | 154篇 |
2007年 | 145篇 |
2006年 | 158篇 |
2005年 | 146篇 |
2004年 | 134篇 |
2003年 | 129篇 |
2002年 | 122篇 |
2001年 | 117篇 |
2000年 | 116篇 |
1999年 | 62篇 |
1998年 | 44篇 |
1997年 | 48篇 |
1996年 | 87篇 |
1995年 | 64篇 |
1994年 | 81篇 |
1993年 | 62篇 |
1992年 | 64篇 |
1991年 | 61篇 |
1990年 | 59篇 |
1989年 | 47篇 |
1988年 | 50篇 |
1987年 | 64篇 |
1986年 | 58篇 |
1985年 | 58篇 |
1984年 | 64篇 |
1983年 | 49篇 |
1982年 | 52篇 |
1981年 | 63篇 |
1980年 | 45篇 |
1979年 | 47篇 |
1978年 | 53篇 |
1977年 | 58篇 |
1976年 | 58篇 |
1975年 | 58篇 |
1974年 | 59篇 |
1973年 | 43篇 |
1968年 | 27篇 |
1957年 | 30篇 |
排序方式: 共有4624条查询结果,搜索用时 46 毫秒
21.
22.
Abachi S Derrick M Kooijman P Musgrave B Price LE Repond J Sugano K Blockus D Brabson B Brom J Jung C Ogren H Rust DR Akerlof C Chapman J Errede D Ken MT Meyer DI Neal H Nitz D Thun R Tschirhart R Baringer P Bylsma BG DeBonte R Koltick D Low EH McIlwain RL Miller DH Ng CR Shibata EI 《Physical review D: Particles and fields》1989,40(3):902-905
23.
The Crystal Structure of CsTcO4 CsTcO4 crystallizes orthorhombic with a = 5.727, b = 5.921 and c = 14.34 Å. Z = 4, space group Pnma (Nr. 62, I.T.). The metal positions were refined by single crystal data, the oxygen positions first determined: the CsTcO4 structure is a slight distortion of the scheelite arrangement (parameters: see text). The MADELUNG Part of Lattice Energy, MAPLE, ?Mean Effective Ionic Radii”?, MEIR, and Effective Coordination Numbers, ECoN, are calculated and discussed. 相似文献
24.
Microsatellite structures in the context of human evolution 总被引:2,自引:0,他引:2
Six microsatellite - or short tandem repeat (STR) - systems with uniform repetitive sequences (HumTH01, HumCD4, HumFES/FPS, HumF13B, HumTPO, HumLPL) and three compound repeat systems (HumVWA, HumFIBRA, D21S11) were used, including data from the literature, to determine genetic distances among eight populations worldwide. The TH01- and VWA homologous loci in nonhuman primates (chimpanzees, gorillas, orangutans, rhesus monkeys, ring-tailed lemurs) were compared and found to be shorter than in humans. Microsatellites of lower complexity were most efficient for the separation of major ethnic groups. The loci of higher complexity showed a leveling of the diversity differences among populations, which could be attributed to higher mutation rates. 相似文献
25.
26.
27.
28.
29.
Meyer GJ 《Inorganic chemistry》2005,44(20):6852-6864
Strategies toward the realization of molecular control of interfacial charge transfer at nanocrystalline semiconductor interfaces are described. Light excitation of coordination compounds, based on (dpi)6 transition metals, anchored to wide band-gap semiconductors, such as TiO2, can initiate electron-transfer processes that ultimately reduce the semiconductor. Such photoinduced charge-separation processes are a key step for solar energy conversion. The thermodynamics and kinetic rate constants for three different interfacial charge separation mechanisms are discussed. Tuning the energetic position of the semiconductor conduction band relative to the molecular sensitizer has provided new insights into interfacial charge transfer. Supramolecular compounds that efficiently absorb light, promote interfacial electron transfer, and feature additional functions such as intramolecular electron transfer when bound to semiconductor surfaces have also been studied. New approaches for enhancing charge-separation lifetimes for solar energy conversion are presented. 相似文献
30.
A. Damarupurshad R. J. Hart J. P. F. Sellschop H. O. Meyer 《Journal of Radioanalytical and Nuclear Chemistry》1997,219(1):33-39
Instrumental neutron activation analysis (INAA) has been applied to the analysis of 62 small (0.01–0.5 carat), single, inclusion-bearing and inclusion-free diamonds from South Africa, Brazil and Colorado. Up to 40 elements were detected at the ppb and ppt levels in individual diamonds of the eclogitic (basaltic affinity) and the peridotitic (ultramafic) paragenesis. The data obtained in this study can be used to distinguish between diamonds from the eclogitic and peridotitic parageneses and provides geochemical information on the environment in which diamonds crystallize. Further, the technique may prove to be useful in fingerprinting diamonds of different provenance areas. 相似文献