全文获取类型
收费全文 | 30907篇 |
免费 | 376篇 |
国内免费 | 428篇 |
专业分类
化学 | 12036篇 |
晶体学 | 283篇 |
力学 | 1490篇 |
综合类 | 13篇 |
数学 | 9145篇 |
物理学 | 8744篇 |
出版年
2023年 | 101篇 |
2022年 | 200篇 |
2021年 | 168篇 |
2020年 | 179篇 |
2019年 | 183篇 |
2018年 | 1341篇 |
2017年 | 1551篇 |
2016年 | 864篇 |
2015年 | 711篇 |
2014年 | 641篇 |
2013年 | 858篇 |
2012年 | 3345篇 |
2011年 | 2509篇 |
2010年 | 1936篇 |
2009年 | 1635篇 |
2008年 | 648篇 |
2007年 | 676篇 |
2006年 | 625篇 |
2005年 | 4437篇 |
2004年 | 3904篇 |
2003年 | 2287篇 |
2002年 | 480篇 |
2001年 | 284篇 |
2000年 | 95篇 |
1999年 | 168篇 |
1998年 | 113篇 |
1997年 | 65篇 |
1996年 | 42篇 |
1995年 | 42篇 |
1994年 | 41篇 |
1992年 | 169篇 |
1991年 | 153篇 |
1990年 | 140篇 |
1989年 | 106篇 |
1988年 | 98篇 |
1987年 | 56篇 |
1986年 | 42篇 |
1985年 | 38篇 |
1984年 | 28篇 |
1979年 | 29篇 |
1976年 | 79篇 |
1975年 | 37篇 |
1974年 | 40篇 |
1973年 | 48篇 |
1972年 | 39篇 |
1970年 | 34篇 |
1969年 | 37篇 |
1968年 | 35篇 |
1967年 | 30篇 |
1966年 | 37篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
971.
M.?Droz A.?P?kalski 《The European Physical Journal B - Condensed Matter and Complex Systems》2010,77(4):581-586
We present a new, extended, predator-prey model for which we discuss
the role of predators mobility and hunting effectiveness on the
dynamics of the system. We show, via Monte Carlo simulations, that the
maximum of predators’ population density is a rather complex function
of both – mobility and effectiveness of hunting. For a low mobility,
larger effectiveness suits the predators better. When the
mobility is large, the predators population is bigger if the predators
are rather bad hunters. We have not observed temporal oscillations in
the densities of both species. 相似文献
972.
J. A. Helay?l-Neto L. M. de Moraes V. J. Vasquez 《The European Physical Journal C - Particles and Fields》2010,67(1-2):311-319
In this paper, we reassess the issue of deriving the propagators and identifying the spectrum of excitations associated to the vielbein and spin connection of (1+2)-D gravity in the presence of dynamical torsion, while working in the first-order formulation. A number of peculiarities is pointed out whenever the Chern–Simons term is taken into account along with a combination of bilinear terms in the torsion tensor. We present a procedure to derive the full set of propagators, based on an algebra of enlarged spin-type operators, and we discuss under which conditions the poles of the tree-level 2-point functions correspond to physical excitations that do not conflict with causality and unitarity. 相似文献
973.
974.
Phase resolved optical emission spectroscopy of coaxial microplasma jet operated with He and Ar 总被引:1,自引:0,他引:1
975.
976.
977.
978.
Vivian?Regina?Trist?o Fernando?Felippe?de?Carvalho Cinthia?Zanini?Gomes Adriana?Regina?Miranda Cíntia?C.?Vequi-Suplicy Maria?Teresa?Lamy Nestor?Schor Maria?Helena?Bellini 《Journal of fluorescence》2010,20(3):665-669
The progression to end-stage renal failure is independent of the initial pathogenic mechanism. Metabolic acidosis is a common
consequence of chronic renal failure that results from inadequate ammonium excretion and decreased tubular bicarbonate reabsorption.
Protoporphyrin IX (PpIX) is the immediate metabolic precursor of the heme molecule. The purpose of this study was to evaluate
the levels of erythrocytes protoporphyrin IX at an animal model during progressive renal disease. A total of 36 eight-week-old
male Wistar rats were divided into six groups: Normal, 4 and 8 weeks after 5/6 nephrectomy (NX). Renal function was evaluated
by creatinine clearance and plasma creatinine levels. The autofluorescence of erythrocytes porphyrin of healthy and NX rats
was analyzed using fluorescence spectroscopy. Emission spectra were obtained by exciting the samples at 405 nm. Significant
differences between normal and NX rats autofluorescence shape occurred in the 600–700 nm spectral region. A correlation was
observed between emission band intensity at 635 nm and progression of renal disease. 相似文献
979.
Carlos?M.?Matias Jo?o?M.?Sousa M.?Emília?Quinta-Ferreira Mona?Arif Hugh?D.?Burrows 《Journal of fluorescence》2010,20(1):377-380
Fura-2 is widely used as a fluorescent probe to monitor dynamic changes in cytosolic free calcium in cells, where Ca2+ can enter through several types of voltage-operated or ligand-gated channels. However, Fura-2 is also sensitive to other
metal ions, such as zinc, which may be involved in ionic channels and receptors. There is interest, in particular, in studying
the synapses between mossy fibers and CA3 pyramidal cells which contain both calcium and high quantities of free or loosely
bound zinc. We have found, through fluorescence probing, that endogenous zinc inhibits mossy fiber calcium transients. However,
since these results might be explained by an effect of the zinc chelator N,N,N’,N’-tetrakis(2-pyridylmethyl)ethylenediamine
(TPEN) on the spectral properties of Fura-2, we have carried out a validation of the method through fluorescence excitation
spectra of the complex Fura-2/calcium, and show that TPEN does not affect these spectra. This supports the idea that the observed
calcium enhancement is related to a zinc inhibition of presynaptic calcium mechanisms, and confirms the use of the chelator
TPEN as a general procedure for the biophysical study of Ca(II) in the presence of Zn(II) using Fura-2. 相似文献
980.
Alfredo?Macías Abel?Camacho Luis?F.?Barragán-Gil Claus?L?mmerzahl 《General Relativity and Gravitation》2010,42(3):489-508
The canonical quantization for N = 1 supergravity in the context of gravitational minisuperspace described by Gowdy T
3 and Bianchi class A cosmological models is analyzed in order to search for physical states. There are indeed physical states
in the minisuperspace sector of the theory. This fact entails that the non-physical states conjecture has a restricted validity,
and in consequence it cannot be considered a general result. 相似文献