全文获取类型
收费全文 | 40678篇 |
免费 | 1394篇 |
国内免费 | 31篇 |
专业分类
化学 | 23381篇 |
晶体学 | 189篇 |
力学 | 846篇 |
综合类 | 1篇 |
数学 | 6699篇 |
物理学 | 10987篇 |
出版年
2022年 | 229篇 |
2021年 | 369篇 |
2020年 | 551篇 |
2019年 | 394篇 |
2018年 | 490篇 |
2017年 | 480篇 |
2016年 | 1082篇 |
2015年 | 917篇 |
2014年 | 1033篇 |
2013年 | 2187篇 |
2012年 | 1783篇 |
2011年 | 2142篇 |
2010年 | 1109篇 |
2009年 | 942篇 |
2008年 | 2013篇 |
2007年 | 1954篇 |
2006年 | 1747篇 |
2005年 | 1568篇 |
2004年 | 1251篇 |
2003年 | 1074篇 |
2002年 | 983篇 |
2001年 | 788篇 |
2000年 | 695篇 |
1999年 | 484篇 |
1998年 | 437篇 |
1997年 | 425篇 |
1996年 | 549篇 |
1995年 | 490篇 |
1994年 | 499篇 |
1993年 | 572篇 |
1992年 | 481篇 |
1991年 | 369篇 |
1990年 | 402篇 |
1989年 | 331篇 |
1988年 | 349篇 |
1987年 | 336篇 |
1986年 | 314篇 |
1985年 | 498篇 |
1984年 | 478篇 |
1983年 | 447篇 |
1982年 | 447篇 |
1981年 | 450篇 |
1980年 | 435篇 |
1979年 | 384篇 |
1978年 | 421篇 |
1977年 | 399篇 |
1976年 | 348篇 |
1975年 | 332篇 |
1974年 | 318篇 |
1973年 | 321篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
51.
A brief account of applications of polarized inelastic neutron scattering in condensed matter research is given. We show that
full polarization analysis is the only tool allowing to discriminate unambiguously between different magnetic modes in various
magnetic materials. We show by means of recent results in the Heisenberg ferromagnet EuS that the effects of dipolar interactions
can be studied on a microscopic scale. Moreover, we have found for the first time indications for the divergence of the longitudinal
fluctuations belowT
c. In the itinerant antiferromagnet chromium we demonstrate that the dynamics of the longitudinal and transverse excitations
are very different, resolving a long standing puzzle concerning the slope of their dispersion. Finally, we show that a measurement
of the polarization-dependent part of the cross section of non-centrosymmetric MnSi proves directly that the chirality of
the magnetic fluctuations is left-handed. 相似文献
52.
53.
54.
Keller Teichmann Hans Pfeiffer W. Langenbeck A. Reid Heinrich Menzel Th. Höpner W. Mühlsteph M. Ulmann Geib R. E. Liesegang 《Colloid and polymer science》1939,87(1):100-104
Ohne Zusammenfassung 相似文献
55.
56.
57.
Ashish Goel Monika R. Henzinger Serge Plotkin Eva Tardos 《Journal of Algorithms in Cognition, Informatics and Logic》2003,48(2):314-332
In this paper we consider the online ftp problem. The goal is to service a sequence of file transfer requests given bandwidth constraints of the underlying communication network. The main result of the paper is a technique that leads to algorithms that optimize several natural metrics, such as max-stretch, total flow time, max flow time, and total completion time. In particular, we show how to achieve optimum total flow time and optimum max-stretch if we increase the capacity of the underlying network by a logarithmic factor. We show that the resource augmentation is necessary by proving polynomial lower bounds on the max-stretch and total flow time for the case where online and offline algorithms are using same-capacity edges. Moreover, we also give polylogarithmic lower bounds on the resource augmentation factor necessary in order to keep the total flow time and max-stretch within a constant factor of optimum. 相似文献
58.
Marco Möller 《Results in Mathematics》2004,46(3-4):271-360
59.
Kerstin Paech Adrian Dumitru Jürgen Schaffner-Bielich Stefan Schramm Horst Stöcker Gebhard Zeeb Detlef Zschiesche 《Acta Physica Hungarica A》2004,21(2-4):151-156
The measured particle ratios in central heavy-ion collisions are investigated within a chemical and thermal equilibrium chiral SU(3) σ?ω approach. Contrary to the commonly adopted non-interacting gas calculations, the chiral SU(3) model predicts modified effective hadron masses and effective chemical potentials in the medium and a transition to a chirally restored phase at high temperatures or chemical potentials. the influence of three different types of phase transitions is investigated. We show that the deduced freeze-out values considerably depend on the underlying model while the quality of the fit is approximately the same. 相似文献
60.
Xiaojuan Hao Camilla Nilsson Martin Jesberger Martina H. Stenzel Eva Malmstrm Thomas P. Davis Emma
stmark Christopher Barner‐Kowollik 《Journal of polymer science. Part A, Polymer chemistry》2004,42(23):5877-5890
The synthesis and characterization of novel first‐ and second‐generation true dendritic reversible addition–fragmentation chain transfer (RAFT) agents carrying 6 or 12 pendant 3‐benzylsulfanylthiocarbonylsulfanylpropionic acid RAFT end groups with Z‐group architecture based on 1,1,1‐hydroxyphenyl ethane and trimethylolpropane cores are described in detail. The multifunctional dendritic RAFT agents have been used to prepare star polymers of poly(butyl acrylate) (PBA) and polystyrene (PS) of narrow polydispersities (1.4 < polydispersity index < 1.1 for PBA and 1.5 < polydispersity index < 1.3 for PS) via bulk free‐radical polymerization at 60 °C. The novel dendrimer‐based multifunctional RAFT agents effect an efficient living polymerization process, as evidenced by the linear evolution of the number‐average molecular weight (Mn) with the monomer–polymer conversion, yielding star polymers with molecular weights of up to Mn = 160,000 g mol?1 for PBA (based on a linear PBA calibration) and up to Mn = 70,000 g mol?1 for PS (based on a linear PS calibration). A structural change in the chemical nature of the dendritic core (i.e., 1,1,1‐hydroxyphenyl ethane vs trimethylolpropane) has no influence on the observed molecular weight distributions. The star‐shaped structure of the generated polymers has been confirmed through the cleavage of the pendant arms off the core of the star‐shaped polymeric materials. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 5877–5890, 2004 相似文献