全文获取类型
收费全文 | 113927篇 |
免费 | 6910篇 |
国内免费 | 4678篇 |
专业分类
化学 | 49211篇 |
晶体学 | 1285篇 |
力学 | 8992篇 |
综合类 | 285篇 |
数学 | 35943篇 |
物理学 | 29799篇 |
出版年
2024年 | 143篇 |
2023年 | 777篇 |
2022年 | 1285篇 |
2021年 | 1327篇 |
2020年 | 1485篇 |
2019年 | 1414篇 |
2018年 | 11357篇 |
2017年 | 11122篇 |
2016年 | 7663篇 |
2015年 | 2573篇 |
2014年 | 2415篇 |
2013年 | 2984篇 |
2012年 | 6911篇 |
2011年 | 13674篇 |
2010年 | 7816篇 |
2009年 | 8162篇 |
2008年 | 8920篇 |
2007年 | 10787篇 |
2006年 | 2334篇 |
2005年 | 2923篇 |
2004年 | 2808篇 |
2003年 | 3042篇 |
2002年 | 2023篇 |
2001年 | 1071篇 |
2000年 | 1154篇 |
1999年 | 971篇 |
1998年 | 920篇 |
1997年 | 825篇 |
1996年 | 881篇 |
1995年 | 730篇 |
1994年 | 613篇 |
1993年 | 523篇 |
1992年 | 477篇 |
1991年 | 391篇 |
1990年 | 351篇 |
1989年 | 297篇 |
1988年 | 262篇 |
1987年 | 229篇 |
1986年 | 210篇 |
1985年 | 199篇 |
1984年 | 146篇 |
1983年 | 107篇 |
1982年 | 101篇 |
1981年 | 74篇 |
1980年 | 62篇 |
1979年 | 54篇 |
1914年 | 45篇 |
1912年 | 40篇 |
1909年 | 41篇 |
1908年 | 40篇 |
排序方式: 共有10000条查询结果,搜索用时 10 毫秒
341.
342.
343.
344.
Ben Craps Matthias R. Gaberdiel Jeffrey A. Harvey 《Communications in Mathematical Physics》2003,234(2):229-251
We study D-branes in the bosonic closed string theory whose automorphism group is the Bimonster group (the wreath product
of the Monster simple group with ℤ2). We give a complete classification of D-branes preserving the chiral subalgebra of Monster invariants and show that they
transform in a representation of the Bimonster. Our results apply more generally to self-dual conformal field theories which
admit the action of a compact Lie group on both the left- and right-moving sectors.
Received: 20 February 2002 / Accepted: 17 August 2002 Published online: 19 December 2002
Communicated by R.H. Dijkgraaf 相似文献
345.
346.
We give combinatorial proofs that certain families of differences of products of Schur functions are monomial-positive. We
show in addition that such monomial-positivity is to be expected of a large class of generating functions with combinatorial
definitions similar to Schur functions. These generating functions are defined on posets with labelled Hasse diagrams and
include for example generating functions of Stanley's (P,ω)-partitions.
T.L. was supported in part by NSF DMS-0600677. 相似文献
347.
In this research, a simple, sensitive chemiluminescence (CL) method for the determination of humic acid (HA) in water samples was first developed based on the redox reaction between humic acid and cerium(IV) in the acidic condition. Different with the former redox CL reaction which occurred in alkaline solution, no enhancers were needed and neither precipitation nor a second contamination would occur in the present CL system. Comparing with other spectrometric methods, we find that the proposed analysis system had better applicability and accuracy. Under the optimal experiment conditions, the CL peak height was linear with the concentration of HA in the range of 0.03 to 10.0 microg mL(-1). The detection limit is 0.01 microg mL(-1) (S/N = 3), and the relative standard deviation was 2.3% for 0.5 microg mL(-1) HA solution with eleven repeated measurements. The present CL method was successfully applied to the determination of HA in tap water, spring water and river water samples with good recovery from 90.0 to 110.0%. A possible CL mechanism was proposed based on the results of UV and fluorescence spectrometry and the CL spectrum of HA. It was speculated that the semi-quinone radicals in the excited state were the emitters. 相似文献
348.
A Network Simulation of High-congestion Road-traffic Flows in Cities with Marine Container Terminals
James A. Pope Terry R. Rakes Loren Paul Rees Ingrid W. M. Crouch 《The Journal of the Operational Research Society》1995,46(9):1090-1101
Port cities where marine cargo terminals are located are generally near urban areas characterized by high-congestion road traffic. Changes in cargo traffic volumes into a marine terminal, or in the surrounding traffic arteries, which carry this traffic, can significantly affect the terminal's operations. Conversely, activity at the terminal can have an impact on the traffic levels and congestion for a considerable distance from the terminal. This paper demonstrates a methodology useful for studying the impact of road traffic flows on marine container terminals located in highly congested areas. This model was developed at the request of the Virginia Center for World Trade and was used to answer three planning questions in the port of Hampton Roads, Virginia, USA-what would be the impact of: opening a new section of interstate highway, a projected doubling of container traffic at one terminal, and a daily unit train in the vicinity of another terminal. The problem was made more challenging by limited data-collection funds. None the less, the model was deemed valid by a panel of traffic experts and officials from several major state and private agencies involved in marine traffic management. The model results were subsequently a factor in two major decisions related to terminal management. 相似文献
349.
We study the tangent space at a monomial point M in the Hilbert scheme that parameterizes all ideals with the same Hilbert function as M over an exterior algebra. 相似文献
350.
Tai-Man Tang 《Journal of Mathematical Sciences》2007,144(5):4504-4510
Wildly embedded tiles in ℝ3 with spherical boundary are discussed. The construction of the topologically complicated, crumpled cube tiles is reviewed.
We construct an infinite family of wildly embedded, cellular tiles with Fox-Artin-type wild points. Finally, a condition on
the set of wild points on a cellular tile is given to show that certain wild cells cannot be tiles. Several observations are
recorded for further investigations.
__________
Translated from Fundamentalnaya i Prikladnaya Matematika, Vol. 11, No. 4, pp. 203–211, 2005. 相似文献