全文获取类型
收费全文 | 342670篇 |
免费 | 3071篇 |
国内免费 | 964篇 |
专业分类
化学 | 168364篇 |
晶体学 | 5472篇 |
力学 | 17475篇 |
综合类 | 12篇 |
数学 | 57509篇 |
物理学 | 97873篇 |
出版年
2021年 | 2175篇 |
2020年 | 2561篇 |
2019年 | 2846篇 |
2018年 | 13664篇 |
2017年 | 13651篇 |
2016年 | 11194篇 |
2015年 | 3872篇 |
2014年 | 5314篇 |
2013年 | 12218篇 |
2012年 | 12560篇 |
2011年 | 20819篇 |
2010年 | 13315篇 |
2009年 | 13680篇 |
2008年 | 15984篇 |
2007年 | 17875篇 |
2006年 | 9235篇 |
2005年 | 9294篇 |
2004年 | 8851篇 |
2003年 | 8725篇 |
2002年 | 7640篇 |
2001年 | 8278篇 |
2000年 | 6283篇 |
1999年 | 4728篇 |
1998年 | 3886篇 |
1997年 | 3745篇 |
1996年 | 3554篇 |
1995年 | 3256篇 |
1994年 | 3123篇 |
1993年 | 2983篇 |
1992年 | 3634篇 |
1991年 | 3577篇 |
1990年 | 3483篇 |
1989年 | 3525篇 |
1988年 | 3475篇 |
1987年 | 3424篇 |
1986年 | 3270篇 |
1985年 | 4105篇 |
1984年 | 4185篇 |
1983年 | 3351篇 |
1982年 | 3478篇 |
1981年 | 3451篇 |
1980年 | 3195篇 |
1979年 | 3570篇 |
1978年 | 3627篇 |
1977年 | 3761篇 |
1976年 | 3501篇 |
1975年 | 3214篇 |
1974年 | 3199篇 |
1973年 | 3149篇 |
1972年 | 2207篇 |
排序方式: 共有10000条查询结果,搜索用时 296 毫秒
991.
High-frequency characteristics of CoFeVAlONb thin films were studied. A thin film of Co43.47Fe35.30V1.54Al5.55O9.93Nb4.21 is observed to exhibit excellent magnetic properties; magnetic coercivity of 1.24 Oe, uniaxial in-plane anisotropy field of 66.99 Oe, and saturation magnetization of 19.8 kG. The effective permeability of the film is as high as 1089 and is stable up to 1.8 GHz, and with ferromagnetic resonance over 3 GHz. This film also has very high electrical resistivity of about 628 μΩ cm. These superior properties make it ideal for high-frequency magnetic applications. 相似文献
992.
O.E. Petrova N.B. Tarasova A.Ju. Alyabyev M.N. Davydova N.L. Loseva 《Thermochimica Acta》2006,445(1):67-69
Calorimetric results indicate that nitrocellulose (NC)-induced changes in the metabolism of Desulfovibrio desulfuricans 1388 are caused by both chemical (nitrate) and physical (biofilm formation) factors. Nitrate added to lactate-based culture medium with nitrocellulose competed for the electron flux from lactate and suppressed the bacterial sulfidogenesis and growth. The presence of an insoluble compound (carbon backbone of the polymer) induced the creation of a biofilm-like structure with its own metabolism. 相似文献
993.
Yu. D. Perfiliev V. S. Rusakov L. A. Kulikov A. A. Kamnev K. Alkhatib 《Hyperfine Interactions》2006,167(1-3):881-885
To explain line broadening in emission Mössbauer spectra as compared to the corresponding absorber measurements, the model of trapped electrons has been proposed. Auger electrons (emitted, e.g. after electron capture by 57Co or after the converted isomeric transition of 119mSn), as well as secondary electrons, may be trapped in the proximity to the nucleogenic ion. Electrons captured by lattice traps at different distances from the daughter ion induce an asymmetric distribution of quadrupole splitting in the resulting emission spectra, as shown in a few examples. This model is supported by estimates of quadrupole splitting values which may be caused by such trapped electrons located at specified distances from the nucleogenic atom. 相似文献
994.
Rare earths exhibit complex magnetic phase diagrams resulting from the competition between various contributions to the magnetic
energy: exchange, anisotropy and magnetostriction. The epitaxy of a rare-earth film on a substrate induces (i) a clamping
to the substrate and (ii) pseudomorphic strains. Both these effects are shown to lead to modifications of the magnetic properties
in (0 0 1)Dy, (0 0 1)Tb and (1 1 0)Eu films. In Dy and Tb films, spectacular variations of the Curie temperature have been
evidenced. Additionally, Tb films exhibit a new large wavelength magnetic modulation. In Eu films, one of the helical magnetic
domains disappears at low temperature whereas the propagation vectors of the other helices are tilted. The link between structural
and magnetic properties is underlined via magnetoelastic models. Moreover, molecular beam epitaxy permits the growth of Sm
in a metastable dhcp phase. The magnetic structure of dhcp Sm has been elucidated for the first time. In this review, neutron
scattering is shown to be a powerful technique to reveal the magnetic structures of rare-earth films. 相似文献
995.
Sunanda Banerjee Rohini M Godbole Sreerup Raychaudhuri Ben Allanach Sunanda Banerjee Satyaki Bhattacharyya Debajyoti Choudhury Siba Prasad Das Anindya Datta Rohini M Godbole Monoranjan Guchait Sabine Kraml Gobinda Majumdar David Miller Margarete Mühlleitner Nobuchika Okada Maxim Perelstein Santosh K Rai Sreerup Raychaudhuri Saurabh D Rindani DP Roy K Sridhar Rishikesh Vaidya D Zeppenfeld 《Pramana》2006,67(4):617-637
This is summary of the activities of the working group on collider physics in the IXth Workshop on High Energy Physics Phenomenology
(WHEPP-9) held at the Institute of Physics, Bhubaneswar, India in January 2006. Some of the work subsequently done on these
problems by the subgroups formed during the workshop is included in this report. 相似文献
996.
We analyze the spectra of pions and protons in heavy-ion collisions at relativistic energies from 2 A GeV to 65+65 A GeV by
using a jet-implemented hadron-string cascade model. In this energy region, hadron transverse mass spectra first show softening
until SPS energies, and re-hardening may emerge at RHIC energies. Since hadronic matter is expected to show only softening
at higher energy densities, this re-hardening of spectra can be interpreted as a good signature of the quark-gluon plasma
formation 相似文献
997.
998.
999.
The stannous chloride dihydrate-mediated deprotection-bicyclisation of a range of amides possessing a pendant acetal group is reported. These mild reaction conditions have been used to prepare a number of ring-fused heterocyclic compounds, some in enantiomerically pure form, which should be of interest both in their own right and as building blocks for the production of more complex target molecules. 相似文献
1000.
We study property (T) and the fixed-point property for actions on L
p
and other Banach spaces. We show that property (T) holds when L
2 is replaced by L
p
(and even a subspace/quotient of L
p
), and that in fact it is independent of 1≤p<∞. We show that the fixed-point property for L
p
follows from property (T) when 1<p< 2+ε. For simple Lie groups and their lattices, we prove that the fixed-point property for L
p
holds for any 1< p<∞ if and only if the rank is at least two. Finally, we obtain a superrigidity result for actions of irreducible lattices
in products of general groups on superreflexive spaces.
Bader partially supported by ISF grant 100146; Furman partially supported by NSF grants DMS-0094245 and DMS-0604611; Gelander
partially supported by NSF grant DMS-0404557 and BSF grant 2004010; Monod partially supported by FNS (CH) and NSF (US). 相似文献