全文获取类型
收费全文 | 114541篇 |
免费 | 19194篇 |
国内免费 | 14250篇 |
专业分类
化学 | 80549篇 |
晶体学 | 1324篇 |
力学 | 6625篇 |
综合类 | 946篇 |
数学 | 14159篇 |
物理学 | 44382篇 |
出版年
2024年 | 378篇 |
2023年 | 2209篇 |
2022年 | 4040篇 |
2021年 | 4166篇 |
2020年 | 4537篇 |
2019年 | 4324篇 |
2018年 | 4023篇 |
2017年 | 3739篇 |
2016年 | 5419篇 |
2015年 | 5435篇 |
2014年 | 6649篇 |
2013年 | 8571篇 |
2012年 | 10170篇 |
2011年 | 10386篇 |
2010年 | 7391篇 |
2009年 | 7130篇 |
2008年 | 7570篇 |
2007年 | 6758篇 |
2006年 | 6360篇 |
2005年 | 5289篇 |
2004年 | 4214篇 |
2003年 | 3366篇 |
2002年 | 3167篇 |
2001年 | 2626篇 |
2000年 | 2371篇 |
1999年 | 2357篇 |
1998年 | 1936篇 |
1997年 | 1748篇 |
1996年 | 1756篇 |
1995年 | 1517篇 |
1994年 | 1397篇 |
1993年 | 1148篇 |
1992年 | 1011篇 |
1991年 | 865篇 |
1990年 | 740篇 |
1989年 | 578篇 |
1988年 | 439篇 |
1987年 | 400篇 |
1986年 | 383篇 |
1985年 | 306篇 |
1984年 | 228篇 |
1983年 | 179篇 |
1982年 | 151篇 |
1981年 | 98篇 |
1980年 | 87篇 |
1979年 | 43篇 |
1978年 | 44篇 |
1976年 | 36篇 |
1975年 | 32篇 |
1957年 | 28篇 |
排序方式: 共有10000条查询结果,搜索用时 8 毫秒
171.
Jie Xue Liang Chen Li Zhou Zhifeng Jia Yanping Wang Xinyuan Zhu Deyue Yan 《Journal of Polymer Science.Polymer Physics》2006,44(15):2050-2057
α‐Cyclodextrin (α‐CD) has been complexed with various poly(ethylene glycol) (PEG) derivatives in aqueous solution. It has been found that the end groups of PEG derivatives affect the complexation kinetics greatly, but have only a little influence on the thermodynamic behavior. By increasing the hydrophobicity of end groups, the complexation speeds up rapidly. On the other hand, the bulky end groups slow down the threading of polymeric guests into the cavity of CD. By changing the hydrophobicity and the size of end groups, the complexation rate can be adjusted in the range of several orders of magnitudes, which should be quite useful in the design of new supramolecular systems. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 2050–2057, 2006 相似文献
172.
In this paper we discuss thermodynamics parameters of black hole horizon and cosmological horizon in general high-dimensional space-time. We obtain that the entropy of a cosmological horizon can be described by the Cardy-Verlinde formula. However, the entropy of black hole horizon will be expressed in a form of the Cardy-Verlinde formula, if one adopts the methods given by Abbott and Deser to compute the mass of a black hole in general high-dimensional space-time. Through discussion, relation among various thermodynamics parameters of the black hole in general high-dimensional space-time is given. That is, differential formula of the first law of thermodynamics is obtained. Because we discuss the general high-dimensional space-time, our result has universality.
PACS: 04.20.Dw, 97.60.Lf 相似文献
173.
C.-S. Huang T. Li L. Wei Q.-S. Yan 《The European Physical Journal C - Particles and Fields》2002,23(1):195-199
It is shown that new sources of CP violation can be generated in models with more than one extra dimension. In the supersymmetric models on the space-time , where the radius moduli have auxiliary vacuum expectation values and the supersymmetry breaking is mediated by the Kaluza–Klein
states of the gauge supermultiplets, we analyze the gaugino masses and trilinear couplings for two scenarios and obtain the
result that there exist relative CP violating phases among the gaugino masses and trilinear couplings.
Received: 10 October 2001 / Published online: 20 December 2001 相似文献
174.
175.
Xuechao Li 《Graphs and Combinatorics》2006,22(4):503-513
In this paper, we give new lower bounds for the size of Δ-critical graphs with Δ=8,9 which improve the partial results of
Luo [6] and Y. Zhao [12]. 相似文献
176.
In this paper, we first reduce the problem of finding a minimum parity (g,f)-factor of a graph G into the problem of finding a minimum perfect matching in a weighted simple graph G*. Using the structure of G*, a necessary and sufficient condition for the existence of an even factor is derived.
This paper was accomplished while the second author was visiting the Center for Combinatorics, Nankai University.
The research is supported by NSFC 相似文献
177.
178.
In situ flying height testing technology is becoming more and more important in slider–disk interaction analysis and manufacturing quality control of disk drives and head-related components. Triple harmonic method is a quite promising choice for in situ flying height analysis, compared with other in situ methods reported up to now. This paper reports results of investigations on engineering issues of applying triple harmonic method for in situ flying height analysis. The paper reports results of analysis on the effects of various testing conditions on flying height testing repeatability and accuracy. Results suggest that working at reasonable high channel density and working on the ratio between third and first harmonics will be an advantage in terms of both flying height testing sensitivity and testing repeatability. Comparing with media thickness effect, the gap-length variation among different heads will be important if it is to study flying height difference among different heads and the testing is at high channel density. Also, it is suggested to work at AC erased track, in order to reduce the non-linearity caused by hard transition. 相似文献
179.
The solid-liquid interface motion of NaBi(WO4)2 (NBWO) melt crystal growth is observed in an in situ system, in which the whole processes of interface transition from fiat interface and cellular to dendrite are visualized. The spacing of the dendrite under smaller temperature gradient turns out to be larger than that under larger temperature gradient, which is found to be sensitive to the temperature distribution. The mechanism of dendrite growth of NBWO is studied based on the model of the growth units of anion coordination polyhedra. The { 001} face has two apex links, so it shows higher stability and has high growth rate and forms the arm of dendrite, whereas the {010} face has only one apex link, and thus shows relative slower growth rate and firstly forms the branches. 相似文献
180.
A measure of entanglement on n qubits is defined in terms of Wigner-Yanase skew information. It is shown that the measure coincides essentially with the concurrence on two qubits. This uncovers the information-theoretic meaning of the concurrence of entangled states. 相似文献