全文获取类型
收费全文 | 695篇 |
免费 | 37篇 |
专业分类
化学 | 473篇 |
晶体学 | 3篇 |
力学 | 16篇 |
数学 | 86篇 |
物理学 | 154篇 |
出版年
2023年 | 4篇 |
2022年 | 15篇 |
2021年 | 33篇 |
2020年 | 27篇 |
2019年 | 25篇 |
2018年 | 23篇 |
2017年 | 16篇 |
2016年 | 40篇 |
2015年 | 26篇 |
2014年 | 35篇 |
2013年 | 53篇 |
2012年 | 56篇 |
2011年 | 46篇 |
2010年 | 34篇 |
2009年 | 30篇 |
2008年 | 49篇 |
2007年 | 28篇 |
2006年 | 37篇 |
2005年 | 18篇 |
2004年 | 24篇 |
2003年 | 15篇 |
2002年 | 15篇 |
2001年 | 9篇 |
2000年 | 11篇 |
1999年 | 9篇 |
1998年 | 7篇 |
1997年 | 11篇 |
1996年 | 5篇 |
1995年 | 3篇 |
1994年 | 7篇 |
1992年 | 1篇 |
1991年 | 7篇 |
1990年 | 2篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1987年 | 3篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1977年 | 1篇 |
1975年 | 2篇 |
1973年 | 1篇 |
排序方式: 共有732条查询结果,搜索用时 15 毫秒
41.
Chen X Sichelschmidt O Kleemann W Petracic O Binek Ch Sousa JB Cardoso S Freitas PP 《Physical review letters》2002,89(13):137203
The ac susceptibility of a superferromagnetic discontinuous multilayer [Co(80)Fe20(1.4 nm)/Al(2)O3(3 nm)](10) is measured as a function of temperature, frequency, and field amplitude and compared to static and dynamic hysteresis loops. Its properties are successfully mapped onto the predicted [T. Nattermann, V. Pokrovsky, and V. M. Vinokur, Phys. Rev. Lett. 87, 197005 (2001)]] dynamical phase transitions, which link the relaxation, creep, sliding, and switching regimes of pinned domain walls. 相似文献
42.
Experiments with fast folding proteins are beginning to address the relationship between collapse and folding. We investigate how different scenarios for folding can arise depending on whether the folding and collapse transitions are concurrent or whether a nonspecific collapse precedes folding. Many earlier studies have focused on the limit in which collapse is fast compared to the folding time; in this work we focus on the opposite limit where, at the folding temperature, collapse and folding occur simultaneously. Real proteins exist in both of these limits. The folding mechanism varies substantially in these two regimes. In the regime of concurrent folding and collapse, nonspecific collapse now occurs at a temperature below the folding temperature (but slightly above the glass transition temperature). 相似文献
43.
M.S. Hussein H.M. Nussenzveig A.C.C. Villari J.L. Cardoso 《Physics letters. [Part B]》1982,114(1):1-6
A detailed discussion of the optical theorem for heavy-ion scattering is given. It is pointed out that a careful application of this theorem to light heavy-ion systems may yield information about the nuclear interaction at distances corresponding to forward glory trajectories. Applications to several cases are presented. 相似文献
44.
A microscopic theory for rare-earth ferromagnetic hexaborides, such as Eu1-xCaxB6, is proposed on the basis of the double-exchange Hamiltonian. In these systems, the reduced carrier concentrations place the Fermi level near the mobility edge, introduced in the spectral density by the disordered spin background. We show that the transport properties such as the Hall effect, magnetoresistance, frequency dependent conductivity, and dc resistivity can be quantitatively described within the model. We also make specific predictions for the behavior of the Curie temperature T(C) as a function of the plasma frequency omega(p). 相似文献
45.
Experimental Techniques - This paper presents a strengthening technique for traditional load-bearing stone masonry walls. The technique consists in the application of GFRP strips on masonry wall... 相似文献
46.
do Nascimento Hederson Majela dos Santos Andressa Duarte Vitor Anthony Bittencourt Paulo Rodrigo Stival Radovanovic Eduardo Fávaro Silvia Luciana 《Cellulose (London, England)》2021,28(9):5477-5492
Cellulose - In this work lignocellulosic fibers were obtained from Yucca aloifolia L. leaves and their chemical, morphological, thermal and mechanical properties were studied. The fibers were... 相似文献
47.
João R. Cardoso F. Silva Leite 《Journal of Computational and Applied Mathematics》2010,233(11):2867-2875
Two widely used methods for computing matrix exponentials and matrix logarithms are, respectively, the scaling and squaring and the inverse scaling and squaring. Both methods become effective when combined with Padé approximation. This paper deals with the computation of exponentials of skew-symmetric matrices and logarithms of orthogonal matrices. Our main goal is to improve these two methods by exploiting the special structure of skew-symmetric and orthogonal matrices. Geometric features of the matrix exponential and logarithm and extensions to the special Euclidean group of rigid motions are also addressed. 相似文献
48.
49.
50.
This study investigated the variations in human plasma fluoride concentrations ([F]) and sought to determine the causes. Five subjects (27-33 years old) received a low-F diet during the 5 days of the study. Plasma samples and urine were collected every 3 h from 8 a.m. to 8 p.m. F, PTH, Ca and P were analyzed with the electrode, by chemiluminescence, AAS and colorimetry, respectively. A trend for the plasma [F] was found. The peak [F], 0.55 ± 0.11 μmol L−1, occurred at 11 a.m. and the lowest [F], 0.50 ± 0.06 μmol L−1 occurred between 5 and 8 p.m. Plasma [F] were positively correlated with urinary F excretion rates and with serum PTH levels, but not with the Ca or P levels. Serum PTH levels were positively correlated with urinary F excretion rates and negatively correlated with plasma Ca. The results suggest that the renal system seems to control the daily fluctuations in plasma [F]. 相似文献