全文获取类型
收费全文 | 4655篇 |
免费 | 149篇 |
国内免费 | 33篇 |
专业分类
化学 | 3254篇 |
晶体学 | 37篇 |
力学 | 76篇 |
数学 | 622篇 |
物理学 | 848篇 |
出版年
2023年 | 27篇 |
2022年 | 87篇 |
2021年 | 108篇 |
2020年 | 107篇 |
2019年 | 98篇 |
2018年 | 94篇 |
2017年 | 59篇 |
2016年 | 159篇 |
2015年 | 130篇 |
2014年 | 152篇 |
2013年 | 250篇 |
2012年 | 316篇 |
2011年 | 397篇 |
2010年 | 190篇 |
2009年 | 163篇 |
2008年 | 279篇 |
2007年 | 261篇 |
2006年 | 262篇 |
2005年 | 227篇 |
2004年 | 180篇 |
2003年 | 162篇 |
2002年 | 143篇 |
2001年 | 56篇 |
2000年 | 67篇 |
1999年 | 41篇 |
1998年 | 30篇 |
1997年 | 41篇 |
1996年 | 66篇 |
1995年 | 52篇 |
1994年 | 25篇 |
1993年 | 36篇 |
1992年 | 37篇 |
1991年 | 33篇 |
1990年 | 24篇 |
1989年 | 22篇 |
1988年 | 26篇 |
1987年 | 16篇 |
1986年 | 20篇 |
1985年 | 31篇 |
1984年 | 23篇 |
1983年 | 21篇 |
1982年 | 34篇 |
1981年 | 29篇 |
1980年 | 29篇 |
1979年 | 24篇 |
1978年 | 26篇 |
1977年 | 14篇 |
1975年 | 17篇 |
1974年 | 13篇 |
1973年 | 17篇 |
排序方式: 共有4837条查询结果,搜索用时 31 毫秒
21.
Anna Nowak Joanna Zielonka-Brzezicka Magdalena Peruyska Adam Klimowicz 《Molecules (Basel, Switzerland)》2022,27(11)
Epilobium angustifolium L. (EA) has been used as a topical agent since ancient times. There has been an increasing interest in applying EA as a raw material used topically in recent years. However, in the literature, there are not many reports on the comprehensive application of this plant to skin care and treatment. EA contains many valuable secondary metabolites, which determine antioxidant, anti-inflammatory, anti-aging, and antiproliferative activity effects. One of the most important active compounds found in EA is oenothein B (OeB), which increases the level of ROS and protects cells from oxidative damage. OeB also influences wound healing and reduces inflammation by strongly inhibiting hyaluronidase enzymes and inhibiting COX-1 and COX-2 cyclooxygenases. Other compounds that play a key role in the context of application to the skin are flavonoids, which inhibit collagenase and hyaluronidase enzymes, showing anti-aging and anti-inflammatory properties. While terpenes in EA play an important role in fighting bacterial skin infections, causing, among other things cell membrane, permeability increase as well as the modification of the lipid profiles and the alteration of the adhesion of the pathogen to the animal cells. The available scientific information on the biological potential of natural compounds can be the basis for the wider use of EA in skin care and treatment. The aim of the article is to review the existing literature on the dermocosmetic use of E. angustifolium. 相似文献
22.
The effect of laser irradiation on the optical properties of thermally evaporated Se100?x Te x (x=8, 12, 16) chalcogenide thin films has been studied. The result shows that the irradiation causes a shift in the optical gap. The results have been analyzed on the basis of laser irradiation-induced defects in the film. The width of the tail of localized state in the band gap has been evaluated using the Urbach edge method. As the irradiation time increases, the values of the optical energy gap for all compositions decrease, while tail energy width increases. It is also observed that the optical energy gap decreases with increasing Te content in the alloy. These changes are a consequence of an increment in disorder produced by laser irradiation in the amorphous structure of thin film. 相似文献
23.
The hydroxyalkylation reaction has been used to condense benzocrown ethers with various aldehydes and ketones. The condensation reactions are catalyzed by triflic or sulfuric acid. The products from the reactions are bis(benzocrown ethers) and they are formed in good yields (42-98%, 13 examples). 相似文献
24.
The paper provides the complete list of local models forZ 2 l -invariant generic germs of Lagrangian submanifolds of dimension ≦3. Classification is done directly for genrating functions of Lagrangian submanifolds and contains both elementary singularities and non-elementary ones with continuous moduli. The results demonstrate, in particular, that in contrast to the non-equivariant case the classification of equivariant Lagrangian singularities is not subordinated to the classification of symmetric functions up to the right equivariant equivalences. 相似文献
25.
26.
Huang GS Miller DH Pavlunin V Sanghi B Shipsey IP Adams GS Cravey M Cummings JP Danko I Napolitano J He Q Muramatsu H Park CS Thorndike EH Coan TE Gao YS Liu F Artuso M Boulahouache C Blusk S Butt J Dorjkhaidav O Li J Menaa N Mountain R Nandakumar R Randrianarivony K Redjimi R Sia R Skwarnicki T Stone S Wang JC Zhang K Csorna SE Bonvicini G Cinabro D Dubrovin M Briere RA Chen GP Chen J Ferguson T Tatishvili G Vogel H Watkins ME Rosner JL Adam NE Alexander JP Berkelman K Cassel DG Crede V 《Physical review letters》2006,96(3):032003
Using data collected at the psi(3770) resonance with the CLEO-c detector at the Cornell e+e- storage ring, we present searches for 25 charmless decay modes of the psi(3770), mostly multibody final states. No evidence for charmless decays is found. 相似文献
27.
28.
Rousseaux C Gremillet L Casanova M Loiseau P Rabec Le Gloahec M Baton SD Amiranoff F Adam JC Héron A 《Physical review letters》2006,97(1):015001
The excitation and the relaxation of the plasma waves and ion acoustic waves (IAW), respectively, driven by stimulated Raman (SRS) and Brillouin (SBS) backscatterings have been experimentally investigated with short-pulse lasers. The spectra have been obtained with a 0.3 ps time resolution. It is shown that SRS develops before SBS and suddenly decays around the peak of the pump, as the IAW reaches saturation. On this short time scale, electron kinetic effects play a major role for SRS saturation, contrary to ion dynamics. These results are supported by particle-in-cell simulations. 相似文献
29.
Adam NE Alexander JP Berkelman K Cassel DG Crede V Duboscq JE Ecklund KM Ehrlich R Fields L Galik RS Gibbons L Gittelman B Gray R Gray SW Hartill DL Heltsley BK Hertz D Hsu L Jones CD Kandaswamy J Kreinick DL Kuznetsov VE Mahlke-Krüger H Meyer TO Onyisi PU Patterson JR Peterson D Phillips EA Pivarski J Riley D Ryd A Sadoff AJ Schwarthoff H Shepherd MR Stroiney S Sun WM Urner D Wilksen T Weinberger M Athar SB Avery P Breva-Newell L Patel R Potlia V Stoeck H Yelton J Rubin P Cawlfield C 《Physical review letters》2005,94(23):232002
We describe new measurements of the inclusive and exclusive branching fractions for psi(2S) transitions to J/psi using e(+)e(-) collision data collected with the CLEO detector operating at CESR. All branching fractions and ratios of branching fractions reported here represent either the most precise measurements to date or the first direct measurements. Indirectly and in combination with other CLEO measurements, we determine B(chi(cJ) --> gamma(J/psi)) and B[psi(2S) --> light hadrons]. 相似文献
30.
We present a definition of Riemannian manifold in noncommutative geometry. Using products of unbounded Kasparov modules, we show one can obtain such Riemannian manifolds from noncommutative spinc manifolds; and conversely, in the presence of a spinc structure. We also show how to obtain an analogue of Kasparov’s fundamental class for a Riemannian manifold, and the associated notion of Poincaré duality. Along the way we clarify the bimodule and first-order conditions for spectral triples. 相似文献