全文获取类型
收费全文 | 204183篇 |
免费 | 1714篇 |
国内免费 | 593篇 |
专业分类
化学 | 102360篇 |
晶体学 | 3341篇 |
力学 | 9287篇 |
综合类 | 5篇 |
数学 | 22486篇 |
物理学 | 69011篇 |
出版年
2021年 | 1656篇 |
2020年 | 1797篇 |
2019年 | 1998篇 |
2018年 | 2700篇 |
2017年 | 2602篇 |
2016年 | 3767篇 |
2015年 | 2306篇 |
2014年 | 3615篇 |
2013年 | 9091篇 |
2012年 | 7242篇 |
2011年 | 8735篇 |
2010年 | 6044篇 |
2009年 | 5909篇 |
2008年 | 7917篇 |
2007年 | 8083篇 |
2006年 | 7727篇 |
2005年 | 6899篇 |
2004年 | 6425篇 |
2003年 | 5652篇 |
2002年 | 5493篇 |
2001年 | 6427篇 |
2000年 | 4931篇 |
1999年 | 3795篇 |
1998年 | 3038篇 |
1997年 | 3046篇 |
1996年 | 2791篇 |
1995年 | 2613篇 |
1994年 | 2462篇 |
1993年 | 2337篇 |
1992年 | 2691篇 |
1991年 | 2671篇 |
1990年 | 2600篇 |
1989年 | 2396篇 |
1988年 | 2450篇 |
1987年 | 2450篇 |
1986年 | 2280篇 |
1985年 | 2960篇 |
1984年 | 3216篇 |
1983年 | 2631篇 |
1982年 | 2802篇 |
1981年 | 2771篇 |
1980年 | 2637篇 |
1979年 | 2727篇 |
1978年 | 2823篇 |
1977年 | 2819篇 |
1976年 | 2888篇 |
1975年 | 2672篇 |
1974年 | 2645篇 |
1973年 | 2776篇 |
1972年 | 1763篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
921.
P. Weibel D. Malterre M. Grioni B. Dardel Y. Baer 《Zeitschrift für Physik B Condensed Matter》1992,87(2):165-168
High resolution photoemission and bremsstrahlung isochromat spectroscopy experiments have been carried out on CeAg and LaAg. From a comparison between these two compounds, we extract the cerium 4f spectral function, we compare it with band structure calculations and with many-body model simulations based on the single-impurity Anderson Hamiltonian. We show that the localized 4f charge estimated from previous band structure calculations cannot be identified with the 4f occupation number deduced from the Anderson model. 相似文献
922.
The recently proposed Harbola–Sahni local potential in its exchange-only version [Phys. Rev. Lett. 62 , 689 (1989)] is found to give the static dipole and quadrupole polarizabilities for the Neisoelectronic series in excellent agreement with the corresponding Hartree–Fock estimates. © 1992 John Wiley & Sons, Inc. 相似文献
923.
924.
M. Bahra D. Elliott M. Reading R. Ryan 《Journal of Thermal Analysis and Calorimetry》1992,38(4):543-555
A novel instrument is described called the Thin film Analyser (TFA) which quantitatively measures changes in mechanical and rheological properties of drying films in-situ on a test panel. It is based around a simple force-sensing device, capable of carrying various probes, which can be positioned in anX-Y plane over the panel. Temperature control is achieved by means of a heating block under the sample. By imposing a thermal gradient along the block, measurements can be obtained at a series of temperatures in a single experiment. Several applications of the TFA to the drying of curable and latex-based coatings are discussed, as well as some more specialized uses. The TFA concept represents a novel approach to the thermal analysis of thin films.The authors gratefully acknowledge the design, engineering and software development work of the Instrument Group at ICI Paints, in particular John Hayton, Neil Burrows, Tony Evans and Ian Francis, who have now built three versions of the TFA. 相似文献
925.
A. P. Yakubov D. V. Tsyganov L. I. Belen'kii M. M. Krayushkin 《Russian Chemical Bulletin》1991,40(7):1509-1512
A study was carried out on the formylation of a series of aromatic compounds containing two mesitylene or durene residues [dimesityl (I), dimesitylmethane (II), 1,2-dimesitylethane (III), 1,6-dimesitylhexane (IV), dimesityl sulfide (V), 1,1-dimesitylethylene (VI), 1,1-dimesityl-1-butene (VII), and didurylmethane (VIII)] by the action of dichloromethyl methyl ether (DCM) in the presence of A1C13 and TiCl4. The corresponding dialdehydes are the major products. The formylation products when the reaction is carried out in the presence of A1C13 in the case of (I) and (V) contain significant amounts of monoaldehydes, while partial cleavage of the substrates with the formation of products containing only one benzene ring is observed in the case of (II) and (VIII) in addition to formylation.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 7, pp. 1700–1703, July, 1991. 相似文献
926.
NIKITIN S.; PR?TZEL-WOLTERS D. 《IMA Journal of Mathematical Control and Information》1991,8(4):431-439
In 1983 Morse proved, for unknown scalar one-dimensional linearsystems, the nonexistence of rational or polynomial universalstabilizers (UAS). In 1983, Nussbaum gave an example of an analyticUAS. In our paper, it is shown that there exist time-invariantpolynomial UAS's with multidimensional gain adaptation. Thedesign procedure is developed for linear, minimum-phase systemsof relative degree one. Convergence of the closed-loop systemis proved. Some numerical simulations are provided. 相似文献
927.
928.
G. D. Andreetti F. Ugozzoli A. G. Giumanini P. Traldi L. Lassiani A. Varnavas 《Journal of chemical crystallography》1991,21(6):721-728
The decomposition of the gaseous positive ions of the title compounds obtained by electron impact have been completely mapped. The X-ray structural determinations of these two substances established their identity definitively and allowed to reveal some interesting features of these molecules of pharmaceutical interest. 相似文献
929.
930.
N. M. Agababyan M. R. Atayan M. Charlet J. Czyżewski E. A. De Wolf K. Dziunikowska A. M. F. Endler Z. Sh. Garutchava H. R. Gulkanyan R. Sh. Hakobyan J. K. Karamyan D. Kisielewska W. Kittel S. S. Mehrabyan Z. V. Metreveli E. C. Oliveira K. Olkiewicz F. K. Rizatdinova E. K. Shabalina L. N. Smirnova M. D. Tabidze L. A. Tikhonova A. V. Tkabladze A. G. Tomaradze F. Verbeure S. A. Zotkin 《Zeitschrift fur Physik C Particles and Fields》1996,71(1):405-414
The NA22 data onπ ? π ? correlations are analyzed in terms of a number of two- and three-dimensional parametrizations (Gaussian space-time, Goldhaber, Bowler string-like, Bertsch hydrodynamical, Kopylov-Podgoretskii, etc.). Contrary to the results obtained for e+e? andµp collisions, the Goldhaber parametrization, as well as string-like models, fail in describing the hadron-hadron data. Better fits are obtained in the framework of surface-emitting fireball-like models, both when including and excluding hydrodynamical expansion of nuclear matter. Our results indicate that pion radiation occurs at earlier stages of matter evolution than in nuclear collisions. 相似文献