全文获取类型
收费全文 | 457066篇 |
免费 | 5216篇 |
国内免费 | 1597篇 |
专业分类
化学 | 252238篇 |
晶体学 | 6839篇 |
力学 | 18979篇 |
综合类 | 11篇 |
数学 | 51583篇 |
物理学 | 134229篇 |
出版年
2018年 | 2974篇 |
2016年 | 5681篇 |
2015年 | 4525篇 |
2014年 | 6255篇 |
2013年 | 19931篇 |
2012年 | 14373篇 |
2011年 | 17995篇 |
2010年 | 11465篇 |
2009年 | 11329篇 |
2008年 | 16528篇 |
2007年 | 16881篇 |
2006年 | 16216篇 |
2005年 | 14814篇 |
2004年 | 13399篇 |
2003年 | 11883篇 |
2002年 | 11693篇 |
2001年 | 13830篇 |
2000年 | 10612篇 |
1999年 | 8503篇 |
1998年 | 6791篇 |
1997年 | 6664篇 |
1996年 | 6695篇 |
1995年 | 6118篇 |
1994年 | 5863篇 |
1993年 | 5562篇 |
1992年 | 6413篇 |
1991年 | 6162篇 |
1990年 | 5857篇 |
1989年 | 5746篇 |
1988年 | 5939篇 |
1987年 | 5687篇 |
1986年 | 5435篇 |
1985年 | 7666篇 |
1984年 | 7772篇 |
1983年 | 6379篇 |
1982年 | 6818篇 |
1981年 | 6828篇 |
1980年 | 6480篇 |
1979年 | 6751篇 |
1978年 | 6931篇 |
1977年 | 6818篇 |
1976年 | 6709篇 |
1975年 | 6488篇 |
1974年 | 6290篇 |
1973年 | 6470篇 |
1972年 | 3916篇 |
1971年 | 3035篇 |
1968年 | 3375篇 |
1967年 | 3278篇 |
1966年 | 2990篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
201.
H. Ido 《Journal of magnetism and magnetic materials》1987,70(1-3):205-206
Magnetic susceptibilities have been measured for the mixed compounds Mn1−xCrxAs (0≤x≤1) and the compound MnP in the temperature region up to 1400 K. The X1g vs. T curves of Mn1−xCrxAs follow the Curie-Weiss law only in the temperature region where the crystal structure is of the B81 type. Some important problems are pointed out from the data. 相似文献
202.
J. Bourgain 《Israel Journal of Mathematics》1986,54(3):257-265
The dimension-freeL
2-maximal inequality for convex symmetric bodies obtained in [2] is extended forp>3/2. 相似文献
203.
In a previous study, a mathematical model relating surface and bulk behaviours of metals in aqueous solution has been developed. The model was established based on principles of holographic interferometry for measuring microsurface dissolution, i.e. mass loss, and on those of electrochemistry for measuring the bulk electronic current, i.e. corrosion current. In the present work, an optical corrosion meter was built based on the above model. The corrosion meter consists of an electrochemical cell in which the sample is immersed in aqueous solution. Furthermore, the corrosion meter has a holographic camera with a thermoplastic film for in situ processing of holograms in order to obtain real-time holographic interferoms of the sample in the electrochemical cell. Results of the present work indicate that optical holography is a very useful technique for measuring the corrosion current density of different alloys in aqueous solutions. As a result, the corrosion current density of aluminium, stainless steel, and low-carbon steel in 1 M KCl, 1 M NaCl, and 1 M NaOH solutions were obtained. A comparison between the corrosion data of samples showed that the corrosion current density of the stainless steel in 1 M NaCl is nearly three-folds higher than that of the aluminium in 1 M KCl and the low-carbon steel in 1 M NaOH. 相似文献
204.
Y. A. Coutinho J. A. Martins Simões C. M. Porto 《Zeitschrift fur Physik C Particles and Fields》1997,73(4):705-709
In this paper we investigate the effects of heavy Majorana neutrinos in the reaction e + e ? → W + W ?. We consider neutrino masses in the 1–10 TeV region. We show that at LEP II and NLC energies it is possible to use this processes to verify indirect evidence of heavy neutral particles with mixing angles of the order sin2 α = 0.01. We discuss the unitarity restrictions that can be obtained for vector singlet and fermion-mirror-fermion models. 相似文献
205.
L. Bugliaro J. Fröhlich G.M. Graf J. Stubbe C. Fefferman 《Communications in Mathematical Physics》1997,187(3):567-582
A Lieb-Thirring-Sobolev type inequality for Pauli Hamiltonians with magnetic fields is derived. The bound is in terms of an
effective field, whose energy is comparable to that of the magnetic field itself. An application to the stability of matter
in magnetic fields is given.
Received: 19 September 1996 / Accepted: 3 January 1997 相似文献
206.
Applying the mass shell condition forq-deformed open and closed strings, new critical space-time dimensions are derived.
Supported by the Algerian Ministry of High Education and Research under contract NoD2501/17/01/93.
Permanent address. 相似文献
207.
This paper shows that the dimension of internal structure of a component can be measured remotely to a resolution better than 5 μm by use of the combination of high resolution optical microscopy and image processing.A specialised high resolution, long working distance and diffraction limited lens was used to image within the component. A series of digital images were made to map spatially the interior of the component. An edge detector was then used to localise the specific location of features in order that an accurate internal measurement could be made. A visualisation of the internal surface finish was also achieved. 相似文献
208.
No analytic solutions of the Schrödinger equation are known for the quartic anharmonic oscillator. We show in this paper that there are closely related modified quartic oscillators with the potential depending on |x| for which analytic solutions for some states exist. These results can be extended to the higher order oscillators 相似文献
209.
210.
Merck W.F.H. Zatelepin V.N. 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》1997,25(5):947-953
The aim of this paper is to extend our knowledge about the gas-dynamic processes in arcs during immobility time. For this purpose, the conservation equations in a magnetohydrodynamic approximation were coupled with the thermochemical and Maxwell equations. Special features arc the introduction of dissociation and ionization of nitrogen and oxygen, and the simultaneous calculation of the distributions of current density and magnetic induction in the arc. Numerical calculations were performed with a reduced two-dimensional (2-D) time-dependent model. Results of the calculations were compared with measurements. The development in time of the measured and calculated are voltage and arc chamber pressure show very good agreement. The pumping effect of the double vortex in the arc region was confirmed by optical measurements. It is concluded that the three-layer model is a good representation for the main physical features during the immobility time, and that the presence of highly conducting gas in the downstream region of the arc is essential for its downstream movement 相似文献