全文获取类型
收费全文 | 6412篇 |
免费 | 205篇 |
国内免费 | 25篇 |
专业分类
化学 | 4969篇 |
晶体学 | 78篇 |
力学 | 114篇 |
数学 | 499篇 |
物理学 | 982篇 |
出版年
2022年 | 43篇 |
2021年 | 56篇 |
2020年 | 75篇 |
2019年 | 94篇 |
2018年 | 57篇 |
2017年 | 43篇 |
2016年 | 112篇 |
2015年 | 107篇 |
2014年 | 146篇 |
2013年 | 307篇 |
2012年 | 349篇 |
2011年 | 383篇 |
2010年 | 211篇 |
2009年 | 203篇 |
2008年 | 395篇 |
2007年 | 413篇 |
2006年 | 428篇 |
2005年 | 360篇 |
2004年 | 321篇 |
2003年 | 296篇 |
2002年 | 269篇 |
2001年 | 90篇 |
2000年 | 83篇 |
1999年 | 75篇 |
1998年 | 55篇 |
1997年 | 88篇 |
1996年 | 88篇 |
1995年 | 48篇 |
1994年 | 63篇 |
1993年 | 55篇 |
1992年 | 49篇 |
1991年 | 53篇 |
1990年 | 36篇 |
1989年 | 33篇 |
1988年 | 44篇 |
1987年 | 44篇 |
1986年 | 39篇 |
1985年 | 87篇 |
1984年 | 91篇 |
1983年 | 41篇 |
1982年 | 85篇 |
1981年 | 80篇 |
1980年 | 74篇 |
1979年 | 74篇 |
1978年 | 69篇 |
1977年 | 55篇 |
1976年 | 63篇 |
1975年 | 42篇 |
1974年 | 44篇 |
1973年 | 64篇 |
排序方式: 共有6642条查询结果,搜索用时 15 毫秒
11.
12.
In a graph, a cluster is a set of vertices, and two clusters are said to be non-intersecting if they are disjoint or one of them is contained in the other. A clustered graph C consists of a graph G and a set of non-intersecting clusters. In this paper, we assume that C has a compound planar drawing and each cluster induces a biconnected subgraph. Then we show that such a clustered graph admits a drawing in the plane such that (i) edges are drawn as straight-line segments with no edge crossing and (ii) the boundary of the biconnected subgraph induced by each cluster is a convex polygon. 相似文献
13.
14.
Hiroshi Onishi 《Catalysis Surveys from Japan》2002,6(1-2):1-8
The present account describes first time examples of scanning tunneling microscope (STM) visualization of reaction intermediates on a metal oxide surface. The topographic response of reactant-adsorbed TiO2(110) surfaces to a temperature increment or to a pressure increment was monitored as a sequence of STM images. Acetates thermally decomposing to ketene were resolved in a temperature-jump STM observation. The kinetics of the acetate consumption was determined on the number of acetates resolved in the microscope images and agreed with the macroscopic rate law of ketene production. A pressure-jump study revealed how a chemisorbed carboxylate (RCOO-) is exchanged by another carboxylate (R'COO-) supplied from the ambient vapor phase. An impinging R'COOH was immobilized on the top of a RCOO- and then squeezed itself into the monolayer of the RCOO-. One of the carboxylates in the squeezed state returned to the vapor phase via the immobilized state. 相似文献
15.
16.
Nonlinear susceptibility of a quantum dot (QD) embedded in a two-sided cavity, is studied theoretically from a weak-coupling to a strong-coupling regime. In the relevance of a quantum logic gate, the corresponding nonlinear phase shifts (Kerr effect) are estimated for coherent wavepackets including one photon on average. In the weak-coupling regime, the phase shift enhances strongly as a function of a coupling constant between the cavity photon and QD, and eventually saturates in the strong-coupling regime. We also show transmission spectra to evaluate the efficiency of the phase shift. Although the efficiency decreases monotonically in the weak-coupling regime, it rises in the strong-coupling regime. 相似文献
17.
Frequency dependence of ac conductivity from 1 to 105 Hz and time series of the conductivity at 2 kHz were measured along c-axis of thulium nitrate crystal, Tm(NO3)36H2O at temperatures from 203.15 to 293.15 K. The meta-stability was observed. The frequency spectra of the conductivity were similar to those in disorder system. Aging effect was observed. Non-periodic instability (burst) was found. Non-linear dynamical property was characterized by 1/f noise spectrum, limit cycle in return map and dependence of correlation exponent on embedding dimension. 相似文献
18.
We deal with the q-numerical radius of weighted unilateral and bilateral shift operators. In particular, the q-numerical radius of weighted shift operators with periodic weights is discussed and computed. 相似文献
19.
Hiroyasu Nishiguchi Hiroshi Yamada Masaru Ogura Tatsumi Ishihara Yusaku Takita 《Research on Chemical Intermediates》2003,29(7-9):755-760
The oxygen storage capacity of CeO2, Ce0.9Pr0.1O2, Pt?Rh/CeO2 and Pt?Rh/Ce0.9Pr0.1O2 was investigated by conventional GC pulse method and transient pulse techniques. It is shown that incorporation of PrOy into CeO2 matrix strongly promotes oxygen storage capacity (OSC) measured using the transient pulse technique. The improvement of OSC at low temperature is observed in Pt?Rh loaded onto CeO2 and Ce?Pr catalysts. 相似文献
20.