全文获取类型
收费全文 | 848篇 |
免费 | 17篇 |
国内免费 | 9篇 |
专业分类
化学 | 432篇 |
晶体学 | 5篇 |
力学 | 7篇 |
数学 | 159篇 |
物理学 | 271篇 |
出版年
2021年 | 5篇 |
2020年 | 10篇 |
2018年 | 13篇 |
2017年 | 10篇 |
2016年 | 10篇 |
2015年 | 18篇 |
2014年 | 23篇 |
2013年 | 40篇 |
2012年 | 24篇 |
2011年 | 36篇 |
2010年 | 23篇 |
2009年 | 27篇 |
2008年 | 26篇 |
2007年 | 20篇 |
2006年 | 23篇 |
2005年 | 26篇 |
2004年 | 22篇 |
2003年 | 23篇 |
2002年 | 22篇 |
2001年 | 17篇 |
2000年 | 20篇 |
1999年 | 15篇 |
1998年 | 14篇 |
1997年 | 25篇 |
1996年 | 23篇 |
1995年 | 20篇 |
1994年 | 27篇 |
1993年 | 22篇 |
1992年 | 28篇 |
1991年 | 17篇 |
1990年 | 15篇 |
1989年 | 16篇 |
1988年 | 6篇 |
1987年 | 16篇 |
1986年 | 6篇 |
1985年 | 9篇 |
1984年 | 6篇 |
1983年 | 12篇 |
1982年 | 11篇 |
1981年 | 5篇 |
1980年 | 8篇 |
1978年 | 7篇 |
1977年 | 6篇 |
1976年 | 5篇 |
1975年 | 10篇 |
1974年 | 12篇 |
1973年 | 7篇 |
1969年 | 4篇 |
1966年 | 20篇 |
1965年 | 39篇 |
排序方式: 共有874条查询结果,搜索用时 390 毫秒
861.
Yan‐Cong Chen Fu‐Sheng Guo Jun‐Liang Liu Ji‐Dong Leng Dr. Peter Vrábel Prof. Dr. Martin Orendáč Dr. Jan Prokleška Prof. Dr. Vladimír Sechovský Prof. Dr. Ming‐Liang Tong 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(11):3029-3035
The transformation of MnII glycolates (glc) between the three‐dimensional coordination polymer [Mn(glc)2]n ( 1 ) and discrete mononuclear phase [Mn(glc)2(H2O)2] ( 2 ) can be reversibly switched by water molecules, which dramatically change the magnetocaloric effect (MCE) of MnII glycolates from the maximum of 6.9 J kg?1 K?1 in 1 to 60.3 J kg?1 K?1 in 2 . This case example reveals that the effect of magnetic coupling on MCE plays a dominant role over that of other factors such as magnetic density for 3d‐type magnetic refrigerants. 相似文献
862.
Emilio Carrizosa Jonas Harbering Anita Schöbel 《The Journal of the Operational Research Society》2016,67(10):1325-1337
In this paper we consider the location of stops along the edges of an already existing public transportation network. The positive effect of new stops is given by the better access of the passengers to the public transport network, while the passengers’ traveling time increases due to the additional stopping activities of the trains, which is a negative effect for the passengers. The problem has been treated in the literature where the most common model is to cover all demand points with a minimal number of new stops. In this paper, we follow this line and seek for a set of new stops covering all demand points but instead of minimizing the number of new stops we minimize the additional passengers’ traveling time due to the new stops. For computing this additional traveling time we do not only take the stopping times of the vehicles but also acceleration and deceleration of the vehicles into account. We show that the problem is NP-hard, but we are able to derive a finite candidate set and two tractable IP formulations. For linear networks we show that the problem is polynomially solvable. We also discuss the differences to the common models from literature showing that minimizing the number of new stops does not necessarily lead to a solution with minimal additional traveling times for the passengers. We finally provide a case study showing that our new model decreases the traveling times for the passengers while still achieving the minimal number of new stops. 相似文献
863.
Wróbel A 《Bioelectrochemistry (Amsterdam, Netherlands)》2008,73(2):117-122
The effect of the presence of charged amphiphiles during the incubation of human erythrocytes in a sucrose-substituted low-Cl(-) solution on the shift of the osmotic resistance profile and the net K+ efflux was investigated. Osmotic fragility was determined by fitting the complementary error function to the haemolysis resistance curve. K+ efflux was calculated from the increase in the K+ concentration in supernatant measured by inductively coupled plasma atomic emission spectrometry (ICP-AES). The cationic amphiphile hexadecyltrimethylammonium bromide (CTAB) at 14 microM decreases, whereas the anionic amphiphile sodium dodecyl sulfate (SDS) at 50 microM increases the shift of the haemolysis resistance curve of erythrocytes incubated in isotonic sucrose by 0.069 and 0.079 %NaCl, respectively. Both the positively and the negatively charged amphiphile caused a significant change in the K+ efflux into isotonic sucrose solution: CTAB decreased and SDS increased K+ efflux by about 40%. In view of the lack of effect of the investigated compounds on the haemolysis resistance curve and K+ efflux from human erythrocytes incubated in isotonic NaCl solution, these results suggest that the insertion of charged amphiphiles into the erythrocyte membrane modulates the properties of the K+ transport pathway which is activated under low ionic strength (LIS) conditions. 相似文献
864.
Feyen O Lueking A Kowald A Stephan C Meyer HE Göbel U Niehues T 《Analytical and bioanalytical chemistry》2008,391(5):1713-1720
Tumor necrosis factor-alpha inhibitors are widely and successfully used to treat rheumatic diseases. However, significant side effects have been reported. To detect the potential off-target activities of such inhibitors we characterized two therapeutic antibodies (adalimumab, infliximab) and one receptor fusion protein (etanercept) on protein biochips (UNIchip AV-400) containing a printed serial dilution of tumor necrosis factor-alpha and about 384 different human proteins. Etanercept binds to ten proteins (affinity: 20-33% of tumor necrosis factor-alpha recognition), and six of these proteins are related to ribosomal proteins. Interestingly, adalimumab binds to the same six proteins related to ribosomal proteins (affinity: 12-18%) as well as to four proteins crucially involved in ribosomal protein synthesis. Alignment of protein sequences indicates no significant sequence homology between these ten proteins bound by the biological drugs with the highest off-target activities. Taken together, our in vitro results demonstrate that a significant number of proteins are recognized by tumor necrosis factor-alpha inhibitors and are related to ribosome biogenesis. 相似文献
865.
866.
Under the assumption that is perfect, a representation theorem for locally defined operators mapping the space C
m
(A) of Whitney differentiable functions into C
1(A) is given and an open problem is presented. 相似文献
867.
I. Ennen S. Löffler C. Kübel D. Wang A. Auge A. Hütten P. Schattschneider 《Journal of magnetism and magnetic materials》2012
We report site-specific energy loss magnetic dichroism measurements of the technologically interesting Heusler alloy Ni2MnSn. In addition, we confirm the theoretical prediction that under certain conditions, two different atoms on inequivalent lattice sites give dichroic signals with opposite signs. With this, it is possible to distinguish the magnetic moments of atomic columns that are merely 1.5 Å apart using a conventional transmission electron microscope without the need for aberration corrections. 相似文献
868.
J. Lal D. Abernathy L. Auvray O. Diat G. Grübel 《The European physical journal. E, Soft matter》2001,4(3):263-271
We have studied the static and dynamic behaviour of magnetic colloidal systems (ferrofluids) by Small-Angle X-ray Scattering
(SAXS) and X-ray Photon Correlation Spectroscopy (XPCS). The main features of the novel XPCS technique will be illustrated
by data taken on a model system, colloidal silica spheres. We will then present the results obtained on an optically opaque
suspension of magnetic colloids (maghemite) in the wave vector range from 10-3 to 10-2?^-1. Translational diffusion in zero field and anisotropic diffusion under external magnetic fields will be discussed.
Received 9 August 1999 and Received in final form 26 July 2000 相似文献
869.
N. Buforn A. Astier R. Duffait M. Meyer S. Perriès A. Prévost N. Redon O. Stézowski A. Goergen H. Hübel E. Mergel S. Neumann D. Rossbach N. Nenoff G. Schoenwasser A. Bauchet I. Deloncle M.G. Porquet A.N. Wilson R. Lucas F.A. Beck D. Curien G. Duchêne B.J.P. Gall N. Kintz J.P. Vivien D.M. Cullen 《The European Physical Journal A - Hadrons and Nuclei》2000,9(1):29-34
This work has established eight cross-talk transitions between the two signature partner superdeformed (SD) bands in 197Pb with the EUROBALL IV spectrometer. Directional correlations from oriented states measurements confirm the ΔI = 1 character of these transitions. The flat behaviour of the dynamical moment of inertia and the agreement between the experimental
and microscopic HF+BCS values of (g
K - g
R)K/Q
0 suggest that the configuration of the SD bands is based upon the υ[752]5/2- neutron intruder orbital. The derived effective spin gyromagnetic factor g
s
eff is found to be not quenched, and is close to the theoretical g
s
free value.
Received: 14 June 2000 / Accepted: 14 September 2000 相似文献
870.
D. Roßbach A. N. Wilson C. Barton M. P. Carpenter D. M. Cullen H. Hübel R. V. F. Janssens S. L. King A. Korichi A. T. Reed 《Nuclear Physics A》1999,660(4):1-405
The superdeformed nucleus 193Pb has been studied following a heavy-ion fusion-evaporation reaction with the Gammasphere spectrometer array. Three new superdeformed bands, two of them probably signature partners, have been observed, bringing the total number of superdeformed bands known in this nucleus to nine. An estimate of the g-factor associated with one of the previously known pairs of strongly coupled excited bands has been made, confirming their configuration. The properties of the bands are compared with the results of cranked shell model calculations; good agreement is found and configurations are assigned to each band. The two new signature partner bands are suggested to be based on the two signatures of the [512]5/2 neutron orbital. The third new band is probably based on the 73 intruder orbital. In addition, the high-energy region of the spectrum in coincidence with the yrast superdeformed bands has been carefully studied. The current data provide no evidence for the previously reported transitions linking the superdeformed and normal-deformed states with energies around 2.2–2.4 MeV. 相似文献