全文获取类型
收费全文 | 14199篇 |
免费 | 348篇 |
国内免费 | 13篇 |
专业分类
化学 | 7448篇 |
晶体学 | 116篇 |
力学 | 290篇 |
综合类 | 1篇 |
数学 | 3151篇 |
物理学 | 3554篇 |
出版年
2021年 | 135篇 |
2020年 | 181篇 |
2019年 | 166篇 |
2018年 | 312篇 |
2017年 | 315篇 |
2016年 | 586篇 |
2015年 | 430篇 |
2014年 | 490篇 |
2013年 | 1155篇 |
2012年 | 714篇 |
2011年 | 904篇 |
2010年 | 542篇 |
2009年 | 480篇 |
2008年 | 605篇 |
2007年 | 539篇 |
2006年 | 469篇 |
2005年 | 346篇 |
2004年 | 337篇 |
2003年 | 274篇 |
2002年 | 274篇 |
2001年 | 219篇 |
2000年 | 185篇 |
1999年 | 161篇 |
1998年 | 156篇 |
1997年 | 147篇 |
1996年 | 138篇 |
1995年 | 133篇 |
1994年 | 120篇 |
1993年 | 117篇 |
1992年 | 133篇 |
1991年 | 107篇 |
1990年 | 112篇 |
1989年 | 121篇 |
1988年 | 122篇 |
1987年 | 118篇 |
1986年 | 117篇 |
1985年 | 161篇 |
1984年 | 159篇 |
1983年 | 144篇 |
1982年 | 137篇 |
1981年 | 117篇 |
1980年 | 136篇 |
1979年 | 121篇 |
1978年 | 157篇 |
1977年 | 132篇 |
1976年 | 129篇 |
1975年 | 102篇 |
1974年 | 127篇 |
1973年 | 121篇 |
1965年 | 84篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
A protocol to correct for intra‐ and interspecific variation in tail hair growth to align isotope signatures of segmentally cut tail hair to a common time line 下载免费PDF全文
3.
Formation of porous polymer morphology by microsyneresis during divinylbenzene polymerization 下载免费PDF全文
Libuše Hanková Ladislav Holub Karel Jeřábek 《Journal of Polymer Science.Polymer Physics》2015,53(11):774-781
This article describes the investigation of the importance of various reaction conditions on microsyneretic pore formation during polymerization of divinylbenzene (DVB) under so‐called “solvothermal” conditions. To induce microsyneretic pore formation, the most important parameter is an unusually high dilution of monomers with a “good” porogen solvating the polymer chains. High dilution and solvation of the growing poly(DVB) chains promote the prolongation of the polymer chains rather than their interconnection by crosslinking. Consequently, when the polymer gel density reaches the point where syneresis starts, the polymer network is geometrically too extensive to be broken up into precipitating entities and, instead, porogen droplets are formed within the continuous polymer gel. The pore geometry created by microsyneresis offers high surface area in wide mesopores and hence, high capacity for supporting functional groups or reactions with much better accessibility than narrow pores between polymer microspheres produced by macrosyneresis in conventional styrenic polymer supports. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015 , 53, 774–781 相似文献
4.
5.
6.
7.
Chromatographia - A theoretical model is used to predict retention times of divalent metal cations in single-column ion chromatography using one or more ligands in the eluent. Stability constants... 相似文献
8.
Balázs Szendröi 《Mathematische Zeitschrift》2002,240(2):233-241
This note shows that a certain toric quotient of the quintic Calabi-Yau threefold in provides a counterexample to a recent conjecture of Cox and Katz concerning nef cones of toric hypersurfaces.
Received: 8 February 2001; in final form: 17 September 2001 / Published online: 1 February 2002 相似文献
9.
N. S. Simonović 《Few-Body Systems》2006,38(2-4):139-145
In agreement with the Kohn theorem the relative motion (rel) of three electrons in a two-dimensional parabolic trap separates
from the centre-of-mass (CM) motion. By introducing new coordinates the Hamiltonian for relative motion in the approximation
of non-interacting electrons can be taken to the normal form. The eigenstates of the normalized Hamiltonian are products of
the Fock-Darwin states for normal modes. The energy levels for relative motion are obtained by diagonalizing the exact Hamiltonian
in the eigenbasis for the non-interacting case. In this basis the interaction matrix elements can be obtained in the analytical
form. Since the rank of the Hamiltonian matrix is significantly reduced, the calculations are faster and more accurate than
those for the full (CM + rel) motion. This advantage is especially important for the calculations of excited states and the
analysis of energy spectra. 相似文献
10.
Vijaya Gracias Alan F. Gasiecki Joel D. Moore Irini Akritopoulou-Zanze Stevan W. Djuric 《Tetrahedron letters》2006,47(50):8977-8980
A general method for the preparation of diaza-spirocycles is reported. This method used an olefin metathesis in order to construct the desired spirocyclic framework. Beginning with commercially available protected amino ketones, this strategy ultimately produced pharmacologically relevant diaza-scaffolds in an efficient and high-yielding process. 相似文献