全文获取类型
收费全文 | 11134篇 |
免费 | 680篇 |
国内免费 | 372篇 |
专业分类
化学 | 6940篇 |
晶体学 | 71篇 |
力学 | 547篇 |
综合类 | 40篇 |
数学 | 1672篇 |
物理学 | 2916篇 |
出版年
2023年 | 122篇 |
2022年 | 223篇 |
2021年 | 337篇 |
2020年 | 375篇 |
2019年 | 317篇 |
2018年 | 264篇 |
2017年 | 261篇 |
2016年 | 455篇 |
2015年 | 416篇 |
2014年 | 401篇 |
2013年 | 687篇 |
2012年 | 713篇 |
2011年 | 815篇 |
2010年 | 506篇 |
2009年 | 480篇 |
2008年 | 669篇 |
2007年 | 662篇 |
2006年 | 570篇 |
2005年 | 527篇 |
2004年 | 406篇 |
2003年 | 351篇 |
2002年 | 283篇 |
2001年 | 194篇 |
2000年 | 138篇 |
1999年 | 143篇 |
1998年 | 91篇 |
1997年 | 87篇 |
1996年 | 123篇 |
1995年 | 102篇 |
1994年 | 119篇 |
1993年 | 91篇 |
1992年 | 76篇 |
1991年 | 65篇 |
1990年 | 72篇 |
1989年 | 60篇 |
1988年 | 51篇 |
1987年 | 63篇 |
1986年 | 43篇 |
1985年 | 74篇 |
1984年 | 81篇 |
1983年 | 39篇 |
1982年 | 58篇 |
1981年 | 48篇 |
1980年 | 48篇 |
1979年 | 58篇 |
1978年 | 41篇 |
1977年 | 45篇 |
1976年 | 33篇 |
1975年 | 30篇 |
1974年 | 34篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
Summary Differential scanning calorimetric measurements in the early stage of isothermal crystal growth of polyethylene oxide are
analysed in the light of irreversible thermodynamics. An accurate evaluation of the equilibrium melting temperature is done
by fitting the thermograms obtained at different undercoolings and referring to the activation energy values already known
from the literature.
Paper presented at the I International Conference on Scaling Concepts and Complex Fluids, Copanello, Italy, July 4–8, 1994. 相似文献
62.
Summary The role of chemical reactions in the selection of patterns in phase-separating mixtures is presented. Linearized theory and
computer simulation show that the initial long-wavelength instability characteristic of spinodal decomposition is suppressed
by chemical reactions, which restrict domain growth to intermediate length scales even in the late stages of phase separation.
Our findings suggest that chemical reactions may provide a novel way to stabilize and tune the steady-state morphology of
phase-separating materials.
Paper presented at the I International Conference on Scaling Concepts and Complex Fluids, Copanello, Italy, July 4–8, 1994. 相似文献
63.
研究了油/水界面电解的示差半微分循环伏安行为。在0.01mol/L LiCl(w)-0.01mol/L TBATCIPB(nb)体系“电位窗”比TBATPB(nb)向正方向扩展约50mV,残余电流基本消除,使“电位窗”内的平台向左右拓宽约50mV。算得界面电容约为16μF/cm~2。考察了琥珀酰胆碱离子在w/nb界面的传递伏安特性,结果与一般半微分循环伏安法相似。但峰形改善,检测限降低一个数量级(1×10~(-6)mol/L),相对标准偏差在5%以内,可用于定量测定琥珀酰胆碱。 相似文献
64.
One of the most celebrated results in the theory of hyperspaces says that if the Vietoris topology on the family of all nonempty closed subsets of a given space is normal, then the space is compact (Ivanova-Keesling-Velichko). The known proofs use cardinality arguments and are long. In this paper we present a short proof using known results concerning Hausdorff uniformities. 相似文献
65.
A. Deptuła T. Olczak W. Łada B. Sartowska A.G. Chmielewski C. Alvani P.L. Carconi A. Di Bartolomeo F. Pierdominici S. Casadio 《Journal of Sol-Gel Science and Technology》2003,26(1-3):207-212
Microspheres of Li2TiO3 were fabricated by a classical, inorganic sol-gel process from commercially available TiCl4. Elaborated process consists of the following main steps: (1) dissolving of TiCl4 in concentrated aqueous HCl and addition of LiOH; (2) formation of sol emulsion in 2-ethylhexanol-1 containing the surfactant SPAN-80 (EH); (3) gelation of emulsion drops by extraction of water with partially dehydrated EH; (4) impregnation of gel to Li:Ti molar ratio MR = 2; (5) thermal treatment at 1200°C in order to receive chloride free product. This temperature can be significantly lowered (to 750°C) by dechlorination starting solution TiCl4 by chemical treatment of the with nitric acid to form of nitrate-stabilized titania sols. Tritium release from sol-gel made Li2TiO3 microspheres were found very close to that observed for other traditional materials, however for the first sample process starts slightly earlier. 相似文献
66.
Massimo Camarda Antonino La Magna Francesco La Via 《Journal of computational physics》2007,227(2):1075-1093
A modified Kinetic Lattice Monte Carlo model has been developed to predict growth rate regimes and defect formation in the case of the homo-epitaxial growth of close packed crystalline structures. The model is an improvement over standard Monte Carlo algorithms, which usually retain fixed atom positions and bond partners indicative of perfect crystal lattices. Indeed, we extend the concepts of Monte Carlo growth simulations on super-lattices containing additional sites (defect sites) with respect to those of the reference material. This extension implies a reconsideration of the energetic mapping, which is extensively presented, and allows to describe a complex phenomenology that is out of accessibility of standard stochastic approaches. Results obtained using the Kawasaki and the Bond-Counting rules for the transition probability of the Monte Carlo event are discussed in details. These results demonstrate how the defect types (local or extended), the formation mechanisms and the defect generation regimes can be characterized using our approach. 相似文献
67.
We prove that, under the assumption of the Generalized Riemann Hypothesis, the exponent of the ideal class group of a CM-field
goes to infinity with its absolute discriminant. This gives a positive answer to a question raised by Louboutin and Okazaki
[4].
Received September 10, 2001; in revised form April 5, 2002 相似文献
68.
The hyperreal numbers of nonstandard analysis are characterized in purely algebraic terms as homomorphic images of a suitable class of rings of functions.
69.
70.
Francesco Michelangeli 《Journal of fluorescence》1991,1(3):203-206
A simple fluorimetric method is presented for measuring calcium uptake and inositol 1,4,5-trisphosphate (InsP3)-induced calcium release in microsomes using Fluo-3. This method is used to investigate the amplitude of calcium release (quantal release) induced by InsP3 from rat cerebellum microsomes. 相似文献