全文获取类型
收费全文 | 726篇 |
免费 | 6篇 |
国内免费 | 1篇 |
专业分类
化学 | 374篇 |
晶体学 | 5篇 |
力学 | 8篇 |
数学 | 40篇 |
物理学 | 306篇 |
出版年
2020年 | 6篇 |
2018年 | 7篇 |
2017年 | 12篇 |
2016年 | 9篇 |
2014年 | 11篇 |
2013年 | 65篇 |
2012年 | 46篇 |
2011年 | 38篇 |
2010年 | 21篇 |
2009年 | 25篇 |
2008年 | 36篇 |
2007年 | 30篇 |
2006年 | 30篇 |
2005年 | 21篇 |
2004年 | 21篇 |
2003年 | 15篇 |
2002年 | 20篇 |
2001年 | 13篇 |
2000年 | 16篇 |
1999年 | 13篇 |
1998年 | 4篇 |
1996年 | 9篇 |
1995年 | 11篇 |
1994年 | 9篇 |
1993年 | 9篇 |
1992年 | 10篇 |
1988年 | 4篇 |
1987年 | 8篇 |
1985年 | 7篇 |
1984年 | 7篇 |
1983年 | 7篇 |
1982年 | 8篇 |
1981年 | 4篇 |
1980年 | 6篇 |
1978年 | 4篇 |
1977年 | 4篇 |
1976年 | 7篇 |
1975年 | 5篇 |
1974年 | 6篇 |
1973年 | 9篇 |
1970年 | 4篇 |
1966年 | 6篇 |
1963年 | 4篇 |
1962年 | 9篇 |
1961年 | 7篇 |
1960年 | 10篇 |
1959年 | 13篇 |
1958年 | 24篇 |
1957年 | 8篇 |
1953年 | 4篇 |
排序方式: 共有733条查询结果,搜索用时 46 毫秒
71.
Mitali Banerjee A.K. Majumdar Biplab Sanyal 《Journal of magnetism and magnetic materials》2010,322(21):3558-3564
We report here an experimental study of magnetization of FeNiW alloys at different compositions. We have studied variation of magnetization with temperature (at low external fields) and magnetic field (at low temperatures). The alloy shows para to ferromagnetic transitions across the composition range. We do not find any indication of the spin-glass phase. We have supplemented the experimental work with theoretical analysis using the first-principles tight-binding linear muffin-tin orbitals based augmented space recursion method. Our theoretical estimates of magnetic moment and Curie temperatures agree well with experiment. Our mean-field phase analysis also does not indicate the possibility of a spin-glass phase. 相似文献
72.
73.
Subhabrata Majumdar 《Pramana》2004,63(4):871-875
Surveys of clusters of galaxies provide us with a powerful probe of the density and nature of the dark energy. The red-shift
distribution of detected clusters is highly sensitive to the dark energy equation of state parameterw. Upcoming Sunyaev-Zel’dovich (SZ) surveys would provide us large yields of clusters to very high red-shifts. Self-calibration
of cluster scaling relations, possible for such a huge sample, would be able to constrain systematic biases on mass estimators.
Combining cluster red-shift abundance with limited mass follow-up and cluster mass power spectrum can then give constraints
onw, as well as onσ
8 and ΩM to a few per cents. 相似文献
74.
The thermodynamics of general relativistic systems with boundary, obeying a Hamiltonian constraint in the bulk, is determined
solely by the boundary quantum dynamics, and hence by the area spectrum. Assuming, for large area of the boundary, (a) an
area spectrum as determined by non-perturbative canonical quantum general relativity (NCQGR), (b) an energy spectrum that
bears a power law relation to the area spectrum, (c) an area law for the leading order microcanonical entropy, leading thermal
fluctuation corrections to the canonical entropy are shown to be logarithmic in area with a universal coefficient. Since the
microcanonical entropy also has universal logarithmic corrections to the area law (from quantum space-time fluctuations, as
found earlier) the canonical entropy then has a universal form including logarithmic corrections to the area law. This form
is shown to be independent of the index appearing in assumption (b). The index, however, is crucial in ascertaining the domain
of validity of our approach based on thermal equilibrium. 相似文献
75.
A. H. Lewis D. G. A. L. Aarts P. D. Howell A. Majumdar 《Studies in Applied Mathematics》2017,138(4):438-466
We study planar nematic equilibria on a two‐dimensional annulus with strong and weak tangent anchoring, in the Oseen–Frank theoretical framework. We analyze a radially invariant defect‐free state and compute analytic stability criteria for this state in terms of the elastic anisotropy, annular aspect ratio, and anchoring strength. In the strong anchoring case, we define and characterize a new spiral‐like equilibrium which emerges as the defect‐free state loses stability. In the weak anchoring case, we compute stability diagrams that quantify the response of the defect‐free state to radial and azimuthal perturbations. We study sector equilibria on sectors of an annulus, including the effects of weak anchoring and elastic anisotropy, giving novel insights into the correlation between preferred numbers of boundary defects and the geometry. We numerically demonstrate that these sector configurations can approximate experimentally observed equilibria with boundary defects. 相似文献
76.
A convenient synthesis of 3-substituted pyrazole derivatives by a mixed anhydride method using i-butylchloroformate and N-methylmorpholine at ?20 °C in tetrahydrofuran and study of in vitro antibacterial activities of the prepared compounds against Staphylococcus epidermidis, Bacillus subtilis, Pseudomonas aeruginosa, and Proteus valguris by agar-diffusion method were carried out. The results suggested that the products 4a, 4b, and 4c exhibited moderate to feeble inhibition against all test bacteria at greater concentration but 4d was best against Staphylococcus epidermidis (22 mm) and worst against Pseudomonas aeruginosa (16 mm) at the greatest concentration (2.5 mg/ml), and the activities decreased with decrease in concentration. [Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications® for the following free supplemental resource(s): Full experimental and spectral details.] 相似文献
77.
Majumdar S Hajduczki A Vithayathil R Olsen TJ Spitler RM Mendez AS Thompson TD Weiss GA 《Journal of the American Chemical Society》2011,133(25):9855-9862
Membrane proteins comprise a third of the human genome, yet present challenging targets for reverse chemical genetics. For example, although implicated in numerous diseases including multiple myeloma, the membrane protein caveolin-1 appears to offer a poor target for the discovery of synthetic ligands due to its largely unknown structure and insolubility. To break this impasse and identify new classes of caveolae controlling lead compounds, we applied phage-based, reverse chemical genetics for the discovery of caveolin-1 ligands derived from the anti-HIV therapeutic T20. Substitution of homologous residues into the T20 sequence used a process analogous to medicinal chemistry for the affinity maturation to bind caveolin. The resultant caveolin-1 ligands bound with >1000-fold higher affinity than wild-type T20. Two types of ELISAs and isothermal titration calorimetry (ITC) measurements demonstrated high affinity binding to caveolin by the T20 variants with K(d) values in the 150 nM range. Microscopy experiments with the highest affinity caveolin ligands confirmed colocalization of the ligands with endogenous caveolin in NIH 3T3 cells. The results establish the foundation for targeting caveolin and caveolae formation in living cells. 相似文献
78.
The long-term performance of engineering structures is typically discussed in terms of such concepts as structural integrity,
durability, damage tolerance, fracture toughness, etc. These familiar concepts are usually addressed by considering balance
equations, crack growth relationships, constitutive equations with constant material properties, and constant or cyclically
applied load conditions. The loading histories are represented by changing stress (or strain) states only. For many situations,
especially for those associated with high-performance engineering structures, the local state of the material may also change
during service, so that the properties used in the equations are functions of time and history of applied conditions. For
example, the local values of stiffness, strength, and conductivity are altered by material degradation to create "property
fields" that replace the global constants, and introduce time and history into the governing equations. The present paper
will examine a small set of such problems, which involve the accumulation of distributed damage and the development of an
eventual fracture path leading to failure. Specifically, the paper discusses this problem in the context of material state
changes measured by impedance variations as a method of following the details of fracture path development. An analysis and
interpretations of observations will be presented, and limitations and opportunities associated with this general concept
will be discussed. 相似文献
79.
Two random-walk related problems which have been studied independently in the past, the expected maximum of a random walker
in one dimension and the flux to a spherical trap of particles undergoing discrete jumps in three dimensions, are shown to
be closely related to each other and are studied using a unified approach as a solution to a Wiener-Hopf problem. For the
flux problem, this work shows that a constant c = 0.29795219 which appeared in the context of the boundary extrapolation length, and was previously found only numerically,
can be derived analytically. The same constant enters in higher-order corrections to the expected-maximum asymptotics. As
a byproduct, we also prove a new universal result in the context of the flux problem which is an analogue of the Sparre Andersen
theorem proved in the context of the random walker's maximum. 相似文献
80.