全文获取类型
收费全文 | 1353篇 |
免费 | 35篇 |
国内免费 | 24篇 |
专业分类
化学 | 899篇 |
晶体学 | 17篇 |
力学 | 17篇 |
数学 | 295篇 |
物理学 | 184篇 |
出版年
2022年 | 18篇 |
2021年 | 29篇 |
2020年 | 12篇 |
2019年 | 18篇 |
2018年 | 24篇 |
2017年 | 20篇 |
2016年 | 39篇 |
2015年 | 31篇 |
2014年 | 44篇 |
2013年 | 104篇 |
2012年 | 74篇 |
2011年 | 76篇 |
2010年 | 50篇 |
2009年 | 36篇 |
2008年 | 63篇 |
2007年 | 86篇 |
2006年 | 74篇 |
2005年 | 63篇 |
2004年 | 73篇 |
2003年 | 49篇 |
2002年 | 55篇 |
2001年 | 34篇 |
2000年 | 25篇 |
1999年 | 17篇 |
1998年 | 19篇 |
1997年 | 15篇 |
1996年 | 23篇 |
1995年 | 21篇 |
1994年 | 11篇 |
1993年 | 22篇 |
1992年 | 18篇 |
1991年 | 10篇 |
1990年 | 13篇 |
1989年 | 10篇 |
1988年 | 6篇 |
1987年 | 13篇 |
1986年 | 5篇 |
1985年 | 14篇 |
1984年 | 15篇 |
1983年 | 8篇 |
1982年 | 12篇 |
1981年 | 18篇 |
1980年 | 5篇 |
1979年 | 3篇 |
1978年 | 9篇 |
1977年 | 5篇 |
1974年 | 3篇 |
1973年 | 6篇 |
1972年 | 5篇 |
1970年 | 2篇 |
排序方式: 共有1412条查询结果,搜索用时 31 毫秒
991.
Mariusz M. Gruza Arletta Pokrop Piotr Piatek Janusz Jurczak 《Journal of inclusion phenomena and macrocyclic chemistry》2004,49(1-2):85-89
Eight new chiral macrocyclic diamides derived from D-mannitol and L-threitol, possessing C2 symmetry, are prepared. Their application for alkali metal binding processes is studied using the ESI-MS technique. 相似文献
992.
The structure of tetramethyldialuminoxane was studied. The low‐temperature 1H and 13C NMR spectra suggest that the methyl groups bridge the aluminum atoms in the dialuminoxane trimer. A new method of synthesis of methylaluminoxanes and tetramethyldialuminoxanes in the reaction of tetraethyldiboroxane (organoboron water) with trimethylaluminum (1:1 and 1:2 respectively) was applied to synthesize the investigated system. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
993.
Janusz Walasek 《Journal of Polymer Science.Polymer Physics》1992,30(4):401-408
A solution of polymer chains in the presence of an external electric field is considered. Dipole-like interactions between polymer chain segment-vectors and the electric field are assumed to be proportional to the cosine of the angle between the segment-vector and the direction of the electric field. Parameters characterizing the shape of the chain (i.e., the chain end-to-end distance and cross-section per chain), and parameters describing the local order at the segmental and chain level (i.e., moments of the first and second Legendre polynomials 〈P1〉 and 〈P2〉 are calculated. The optical anisotropy and the molecular shape change induced by the external electric field are discussed. 相似文献
994.
995.
996.
Properties of continuous solutions of a second order polynomial-like iterated functional equation are given by considering
its characteristic. A useful method to discuss the general case is described indeed in this procedure.
Supported by NSF of China, Sichuan Provincial Youth Sci-Tech Foundation and Math. Grant of CAS 相似文献
997.
Janusz Sok 《Applied mathematics and computation》2007,190(2):1157-1160
An interesting criterion was given by Lashin (A.Y. Lashin, Some convolution properties of analytic functions, Appl. Math. Lett. 18 (2005) 135–138) to be starlike for convolution of analytic functions f, g such that Re[f′(z)],Re[g′(z)]β,,β<1 in the unit disc U. In this paper we shall improve this criterion. 相似文献
998.
A dendroid X is said to be weakly arcwise open if for each point p of X each arc component of X?{p} either is open or has empty interior. We study various mapping properties of these dendroids. The leading problem is what classes of mappings between dendroids preserve the property of being weakly arcwise open. 相似文献
999.
Jeffrey K. S. Wan Ivan Kalatchev Janusz Dziak M. Catherine Depew 《Research on Chemical Intermediates》2001,27(9):917-926
Non-alkaline bleaching of thermo-mechanical pulps using 40 MHz RF dielectric capacitor heating is described. Experimental data obtained under RF irradiation are compared with non-alkaline bleaching under pulsed microwave at 2.45 GHz. Optimal processing time is determined. Effectiveness of non-alkaline bleaching of TMP in RF is shown to be close to that in microwave. Neither microwave nor RF irradiation, under non-alkaline bleaching conditions, is shown to result in detriment to the physical properties of the pulp. 相似文献
1000.
The transitions of poly(oxy-2,2′-dimethylazoxybenzene-4,4′-diyloxydodecanedioyl) (PDAD) have been analyzed by differential scanning calorimetry, optical microscopy, and light scattering. The mesophase glass devitrifies at 288 K [ΔCp = 220 J/K mol]. Crystallization from the liquid mesophase can be described between 322 and 362 K by an Avrami expression with an exponent between 3 and 4. Results of light scattering and optical microscopy are in accord with a spherulitic morphology grown after athermal nucleation. Melting of the semicrystalline samples (crystallinity up to 58%) occurs at about 391 K. The heat of fusion of the completely crystalline sample is calculated to be only 13.55 kJ/mol. The mesophase to isotropic phase transition occurs at 418 K with a heat of transition of 4.1 kJ/mol. A general discussion of these transitions is given. 相似文献