全文获取类型
收费全文 | 606149篇 |
免费 | 5413篇 |
国内免费 | 1275篇 |
专业分类
化学 | 275043篇 |
晶体学 | 6929篇 |
力学 | 35399篇 |
综合类 | 7篇 |
数学 | 110391篇 |
物理学 | 185068篇 |
出版年
2021年 | 4516篇 |
2020年 | 5121篇 |
2019年 | 5959篇 |
2018年 | 20991篇 |
2017年 | 20964篇 |
2016年 | 18354篇 |
2015年 | 7457篇 |
2014年 | 10871篇 |
2013年 | 22092篇 |
2012年 | 23592篇 |
2011年 | 35734篇 |
2010年 | 24070篇 |
2009年 | 24299篇 |
2008年 | 30656篇 |
2007年 | 34226篇 |
2006年 | 18544篇 |
2005年 | 20458篇 |
2004年 | 18030篇 |
2003年 | 17228篇 |
2002年 | 15352篇 |
2001年 | 13779篇 |
2000年 | 11100篇 |
1999年 | 8130篇 |
1998年 | 7211篇 |
1997年 | 6905篇 |
1996年 | 6314篇 |
1995年 | 5808篇 |
1994年 | 5739篇 |
1993年 | 5635篇 |
1992年 | 5940篇 |
1991年 | 6236篇 |
1990年 | 6114篇 |
1989年 | 5931篇 |
1988年 | 5780篇 |
1987年 | 5833篇 |
1986年 | 5361篇 |
1985年 | 6677篇 |
1984年 | 7126篇 |
1983年 | 5915篇 |
1982年 | 6378篇 |
1981年 | 6044篇 |
1980年 | 5665篇 |
1979年 | 6200篇 |
1978年 | 6404篇 |
1977年 | 6377篇 |
1976年 | 6602篇 |
1975年 | 6056篇 |
1974年 | 5915篇 |
1973年 | 6236篇 |
1972年 | 4668篇 |
排序方式: 共有10000条查询结果,搜索用时 125 毫秒
991.
V. Tantin 《Fresenius' Journal of Analytical Chemistry》1869,8(1):508
Ohne Zusammenfassung 相似文献
992.
E. Claudon D. Mendelejeff F. Rasiski M. J. Lazarus und L. Godefroy 《Fresenius' Journal of Analytical Chemistry》1886,25(1):375-377
Ohne Zusammenfassung 相似文献
993.
Artur Erdélyi 《Monatshefte für Mathematik》1939,47(1):87-103
Ohne Zusammenfassung 相似文献
994.
995.
V. Balek T. Mitsuhashi I.M. Bountseva H. Haneda Z. Malek J. Šubrt 《Journal of Sol-Gel Science and Technology》2003,26(1-3):185-189
The diffusion structural analysis (DSA) was used to characterize microstructure changes of hydrous titania gel films under in situ conditions of heating. TG and DTA were used in order to elucidate the processes controlling the formation of anatase film during heating of hydrous titania gel film. The annealing of porosity and near surface structure defects of the dehydrated titania films was indicated by DSA in the temperature range 255–700°C as the decrease of radon release rate. It was demonstrated that the annealing was enhanced on heating in oxygen in comparison with heating in argon. The DSA experimental results were compared with model curves describing the radon diffusion mobility and the annealing of radon diffusion paths. 相似文献
996.
997.
For the decay of two identical particles with close momenta, the angular correlations between the directions of emission of decay products are considered on the basis of the model of independent single-particle sources emitting unstable unpolarized particles of nonzero spin. These correlations reflect spin correlations that are caused by quantum-statistics and final-state-interaction effects. A general theory of angular correlations in the decays of two arbitrarily polarized particles (resonances) is constructed. 相似文献
998.
Brodskaya E. I. Lazareva N. F. Ratovskii G. V. 《Russian Journal of General Chemistry》2003,73(7):1062-1064
Acid-base interaction of phenol and 4-nitrophenol with methylbis(1-silatranylmethyl)amine in acetonitrile is completely shifted toward formation of solvation-separated ion pairs. The unusually high electron-donor power of the exocyclic nitrogen atom in the amine is due to the presence of two silatranylmethyl groups exhibiting a super-electron-donor inductive effect. 相似文献
999.
A T Brint 《The Journal of the Operational Research Society》2003,54(11):1177-1188
The annual turnover of online auctions is already in tens of billions of dollars and this amount is predicted to grow substantially over the next few years. Hence, it is important to know how buyers and sellers can influence their chances of success. Therefore, data were collected from eBay auctions for three different categories of collectible items, namely those with a published guide price, those with a rough guide price and those having no easily obtainable guide price. The options available to buyers and sellers of items were then analysed. It was found that it was hard for the seller to influence an item's achieved price significantly, apart from items with no guide price where the starting price could have an effect. Most bidders bid close to the current value and so there were insufficient data to determine the consequences of timing on the placing of high bids. For low bids, delaying a bid was found to improve significantly the chances of winning for one of the data sets. 相似文献
1000.
Koval'chukova O. V. Kuz'mina N. E. Strashnova S. B. Palkina K. K. Mordovina N. I. Zaitsev B. E. Nikitin S. V. 《Russian Journal of Coordination Chemistry》2003,29(2):123-128
Complexes of scandium, yttrium, and lanthanum nitrates with 3-chloro-9-hydroxy-2,4-dimethylpyrido[1,2-a]pyrimidinium perchlorate (HL1ClO4) and 9-hydroxy-2,4-dimethylpyrido[1,2-a]pyrimidinium perchlorate (HL2ClO4) were obtained. Their composition was formulated as Sc(LClO4)2(NO3) and M(LClO4)2(NO3)2 (L = L1 or L2; M = Y or La); structures for the complexes obtained were proposed. The crystal and molecular structure of HL1ClO4 was determined. Dissociation and complexation of HL1ClO4 and HL2ClO4 in aqueous ethanol were studied using the spectroscopic method. Ligand dissociation and complexation constants were calculated. It was shown that a chlorine-containing organic ligand only slightly changes the composition and stability of the metal complexes. 相似文献