全文获取类型
收费全文 | 355666篇 |
免费 | 6978篇 |
国内免费 | 5040篇 |
专业分类
化学 | 171460篇 |
晶体学 | 5290篇 |
力学 | 20979篇 |
综合类 | 332篇 |
数学 | 54317篇 |
物理学 | 115306篇 |
出版年
2021年 | 3608篇 |
2020年 | 3990篇 |
2019年 | 4643篇 |
2018年 | 12618篇 |
2017年 | 12975篇 |
2016年 | 10754篇 |
2015年 | 4952篇 |
2014年 | 7204篇 |
2013年 | 12689篇 |
2012年 | 14585篇 |
2011年 | 22492篇 |
2010年 | 15485篇 |
2009年 | 15807篇 |
2008年 | 19834篇 |
2007年 | 22461篇 |
2006年 | 9943篇 |
2005年 | 13474篇 |
2004年 | 10504篇 |
2003年 | 10072篇 |
2002年 | 8621篇 |
2001年 | 7736篇 |
2000年 | 6034篇 |
1999年 | 4459篇 |
1998年 | 3976篇 |
1997年 | 3793篇 |
1996年 | 3726篇 |
1995年 | 3190篇 |
1994年 | 3348篇 |
1993年 | 3188篇 |
1992年 | 3415篇 |
1991年 | 3554篇 |
1990年 | 3490篇 |
1989年 | 3458篇 |
1988年 | 3279篇 |
1987年 | 3270篇 |
1986年 | 3114篇 |
1985年 | 3755篇 |
1984年 | 3840篇 |
1983年 | 3253篇 |
1982年 | 3192篇 |
1981年 | 3071篇 |
1980年 | 2871篇 |
1979年 | 3353篇 |
1978年 | 3346篇 |
1977年 | 3424篇 |
1976年 | 3547篇 |
1975年 | 3245篇 |
1974年 | 3207篇 |
1973年 | 3386篇 |
1972年 | 2639篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Ulenikov O. N. Tolchenov R. N. Melekhina E. N. Koivusaari M. Alanko S. Anttila R. 《Journal of Molecular Spectroscopy》1995,170(2)
High resolution Fourier transform spectra of deuterated hydrogen sulfide have been recorded in the region 2400-3000 cm−1. Rotational structures of the ν1 + ν2, ν2 + ν3 bands of D232S, of the ν3 and ν1 + ν2 bands of HD32S, and of the ν1 + ν2 band of HD34S were analyzed. Band centers and rotational, centrifugal distortion, and resonance parameters were obtained, which reproduce the initial values of the upper energy levels within a mean accuracy of 1.39 × 10−4 cm−1 for the states (110) and (011) of D232S, 1.61 × 10−4 cm−1 and 1.82 × 10−4 cm−1 for the states (001) and (110) of HD32S, and 2.09 × 10−4 cm−1 for the state (110) of HD34S, respectively. 相似文献
992.
Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, No. 4, pp. 108–112, July–August, 1993. 相似文献
993.
S. Albeverio S. N. Lakaev J. I. Abdullaev 《Functional Analysis and Its Applications》2002,36(3):212-216
A Hamiltonian describing four bosons that move on a lattice and interact by means of pair zero-range attractive potentials is considered. A stronger version of the Hunziker–Van Vinter–Zhislin theorem on the essential spectrum is established. It is proved that the set of eigenvalues lying to the left of the essential spectrum is finite for any interaction energy of two bosons and is empty if this energy is sufficiently small. 相似文献
994.
995.
N. M. Borodachev 《International Applied Mechanics》2002,38(5):556-561
The general solution to the spatial stress problem for an elastic layer is given in a new form. A layer compressed by normal forces uniformly distributed over a square is considered as an example. 相似文献
996.
Yu. V. Belovitskaya I. V. Pekov E. R. Gobechiya N. A. Yamnova Yu. K. Kabalov N. V. Chukanov J. Schneider 《Crystallography Reports》2002,47(2):223-228
The crystal structures of two ancylite specimens from Khibiny massif (the Kola Peninsula, Russia)—ancylite-(Ce) from alkali hydrothermalites (Sr1.01Ca0.02Ba0.01)Σ1.04(Ce0.52La0.28Nd0.11Pr0.04 Sm0.01)Σ0.96(CO3)2(OH0.83F0.13)Σ0.96 · 0.9H2O and ancylite-(Ce) from carbonatites—have (Sr0.80Ca0.05Ba0.01)Σ0.86(Ce0.62La0.40Nd0.09Pr0.03) Σ1.14(CO3)2(OH0.99F0.15)Σ1.14 · 1.0H2O been refined by the Rietveld method. A focusing STOE-STADIP diffractometer with a bent Ge(111) primary monochromator was used (λ MoK α 1 radiation, 2.16° < 2θ < 54.98°; reflection number 237–437). All the computations for ancylite from alkali hydrothermalites were performed within the sp. gr. Pmc21, a = 5.0634(1) Å, b = 8.5898(1) Å, c = 7.2781(1) Å, V = 316.55(1) Å3, R wp = 1.90; the computations for ancylite from carbonatites were performed within the sp. gr. Pmcn, a = 5.0577(1) Å, b = 8.5665(2) Å, c = 7.3151(2) Å, V = 316.94(1) Å3, R wp = 2.38 in the anisotropic approximation of thermal vibrations of cations and oxygen atoms. 相似文献
997.
K. Venkatakrishnan B.K.A. Ngoi P. Stanley L.E.N. Lim B. Tan N.R. Sivakumar 《Applied Physics A: Materials Science & Processing》2002,75(4):493-496
Photomasks are the backbone of microfabrication industries. Currently they are fabricated by a lithographic process, which
is very expensive and time consuming since it is a multi-step process. These issues can be addressed by fabricating photomasks
by direct femtosecond laser writing, which is a single-step process and comparatively cheaper and faster than lithography.
In this paper we discuss our investigations on the effect of two types of laser writing techniques, namely front- and rear-side
laser writing, with regard to the feature size and the edge quality of a feature. It is proved conclusively that for the patterning
of masks, front-side laser writing is a better technique than rear-side laser writing with regard to smaller feature size
and better edge quality. Moreover the energy required for front-side laser writing is considerably lower than that for rear-side
laser writing.
Received: 22 May 2001 / Accepted: 14 September 2001 / Published online: 17 October 2001 相似文献
998.
999.
1000.
B. Pignataro L. Chi S. Gao B. Anczykowski C. Niemeyer M. Adler H. Fuchs 《Applied Physics A: Materials Science & Processing》2002,74(3):447-452
Self-assembled oligomeric nanostructures consisting of bisbiotinylated DNA fragments connected by the protein streptavidin
(STV) are studied by dynamic scanning force microscopy (SFM) operating in air. A comparison of the images taken in repulsive
and attractive regimes is systematically made on DNA and STV structures. Stable and reproducible SFM images are obtained in
the attractive regime by using a special feedback circuit, called Q-control. On the other hand, when SFM is operating in the
repulsive regime, deformation of the structures that reduce the resolution and the image quality are clearly observable. The
heights of both DNA and STV have been measured as a function of the tip/molecule interaction forces. This study offers the
possibility to suggest a different mechanical behavior of DNA with respect to STV.
Received: 24 July 2001 / Accepted: 3 December 2001 / Published online: 4 March 2002 相似文献