全文获取类型
收费全文 | 2881篇 |
免费 | 317篇 |
国内免费 | 398篇 |
专业分类
化学 | 1914篇 |
晶体学 | 37篇 |
力学 | 226篇 |
综合类 | 72篇 |
数学 | 547篇 |
物理学 | 800篇 |
出版年
2023年 | 35篇 |
2022年 | 95篇 |
2021年 | 123篇 |
2020年 | 85篇 |
2019年 | 62篇 |
2018年 | 61篇 |
2017年 | 84篇 |
2016年 | 108篇 |
2015年 | 103篇 |
2014年 | 124篇 |
2013年 | 173篇 |
2012年 | 142篇 |
2011年 | 190篇 |
2010年 | 152篇 |
2009年 | 183篇 |
2008年 | 179篇 |
2007年 | 193篇 |
2006年 | 200篇 |
2005年 | 167篇 |
2004年 | 128篇 |
2003年 | 127篇 |
2002年 | 108篇 |
2001年 | 89篇 |
2000年 | 76篇 |
1999年 | 77篇 |
1998年 | 83篇 |
1997年 | 74篇 |
1996年 | 46篇 |
1995年 | 39篇 |
1994年 | 44篇 |
1993年 | 35篇 |
1992年 | 26篇 |
1991年 | 13篇 |
1990年 | 21篇 |
1989年 | 18篇 |
1988年 | 20篇 |
1987年 | 16篇 |
1986年 | 13篇 |
1985年 | 13篇 |
1984年 | 10篇 |
1983年 | 2篇 |
1982年 | 11篇 |
1981年 | 7篇 |
1980年 | 8篇 |
1979年 | 7篇 |
1978年 | 4篇 |
1976年 | 5篇 |
1973年 | 5篇 |
1972年 | 4篇 |
1957年 | 2篇 |
排序方式: 共有3596条查询结果,搜索用时 328 毫秒
241.
Thermal analysis has been employed to measure changes of the heat capacity of ferromagnetic materials such as alloys in the region of the Curie temperature. Thermal response for these materials is usually small in this region. The necessary increase in sensitivity was achieved by applying temperature modulation. Results obtained by this technique including temperature-modulated differential thermal analysis simultaneously with A.C. thermomagnetometry are presented. 相似文献
242.
We consider a finitecapacity singleserver vacation model with closedown/setup times and Markovian arrival processes (MAP). The queueing model has potential applications in classical IP over ATM or IP switching systems, where the closedown time corresponds to an inactive timer and the setup time to the time delay to set up a switched virtual connection (SVC) by the signaling protocol. The vacation time may be considered as the time period required to release an SVC or as the time during which the server goes to set up other SVCs. By using the supplementary variable technique, we obtain the queue length distribution at an arbitrary instant, the loss probability, the setup rate, as well as the Laplace–Stieltjes transforms of both the virtual and actual waiting time distributions. 相似文献
243.
Piotr Hajlasz 《Proceedings of the American Mathematical Society》1999,127(2):417-423
If is an open set with the sufficiently regular boundary, then the Hardy inequality holds for and , where . The main result of the paper is a pointwise inequality , where on the right hand side there is a kind of maximal function. The pointwise inequality combined with the Hardy-Littlewood maximal theorem implies the Hardy inequality. This generalizes some recent results of Lewis and Wannebo.
244.
Zhijian Wu 《Proceedings of the American Mathematical Society》1999,127(11):3243-3249
We establish a capacitary strong type estimate for Lipschitz space and characterize the related Carleson measures.
245.
T. Matsuo T. Maekawa A. Inaba O. Yamamuro M. Ohama M. Ichikawa T. Tsuchida 《Journal of Molecular Structure》2006,790(1-3):129
The heat capacities of HCrO2 and DCrO2 have been measured at temperatures between 5 and 360 K. A lambda anomaly occurred at 320 K for DCrO2 but not for HCrO2. Infrared spectra were recorded at temperatures between 5 and 405 K. The spectrum of DCrO2 changed at 320 K with respect to the peak wave-number and splitting of some of the vibrations, while those of HCrO2 depended smoothly on temperature. These experimental results are discussed in terms of a deuteration-induced phase transition. 相似文献
246.
An acoustical technique is proposed for determining the thermal diffusivity in solids and the relative difference between
the molar heat capacities at constant pressure and at constant volume. The method, which consists essentially of measuring
the damping of freely vibrating bars, allows determination of the thermal diffusivity with an accuracy better than ±5% and
has the advantage of not requiring a heat source. It also largely eliminates the complications of precise temperature measurements
and insulation of specimen holders. Results are given for tantalum and vanadium over the temperature range 60–300 K. 相似文献
247.
Van Roie B Denolf K Pitsi G Thoen J 《The European physical journal. E, Soft matter》2005,16(4):361-364
We investigated the smectic-A-hexatic-B (SmA-HexB) transition in the liquid-crystal n-hexyl-4-n-pentyloxybiphenyl-4-carboxilate (65OBC) with adiabatic scanning calorimetry. We were able to prove in a direct way that this transition is indeed very weakly first order, as was already suggested in the literature. The latent heat at the transition was determined to be HL = 0.04±0.02 J/g. Our experiments confirm the high value for the heat capacity critical exponent earlier reported, yielding = 0.64±0.05. 相似文献
248.
We study the problem of completely describing the domains that enjoy the generalized multiplicative inequalities of the embedding theorem type. We transfer the assertions for the Sobolev spaces L
p
1() to the function classes that result from the replacement of L
p
() with an ideal space of vector-functions. We prove equivalence of the functional and geometric inequalities between the norms of indicators and the capacities of closed subsets of . The most comprehensible results relate to the case of the rearrangement invariant ideal spaces. 相似文献
249.
Summary. Several compounds may exist in LnCl3–MCl mixtures. Those corresponding to the M
2
LnCl5 and MLn
2Cl7 stoichiometries are formed in a few systems only, with diverse stability strongly dependent on both the corresponding lanthanide
and alkali metal. On the other hand, M
3
LnCl6 that occur in most systems have a far larger stability range and melt congruently. These latter compounds were investigated
in the present work by differential scanning calorimetry and electrical conductivity measurements. The thermodynamic and transport
properties were correlated to structural features and related to the mechanism of compound formation.
Corresponding author. E-mail: Marcelle.Gaune-Escard@polytech.univ-mrs.fr
Received October 2, 2002; accepted November 6, 2002
Published online April 24, 2003
RID="a"
ID="a" This paper is dedicated to Professor H. Gamsj?ger on the occasion of his birthday 相似文献
250.
We study a two-layer neural network made of N and M(N) neurons, producing a two-way association search for a family of p(N) patterns, where each pattern is a pair of two independent sub-categories of information having respectively N and M(N) components. In terms of the ratio =lim
N
M(N)/N, we study the retrieval capability of this network and show that there exists, at least, three regimes of association for which we determine the evolution of the threshold
c
() of the storage capacity =lim
N
p(N)/N. 相似文献