全文获取类型
收费全文 | 2331篇 |
免费 | 54篇 |
国内免费 | 20篇 |
专业分类
化学 | 1434篇 |
晶体学 | 20篇 |
力学 | 84篇 |
数学 | 441篇 |
物理学 | 426篇 |
出版年
2021年 | 25篇 |
2020年 | 27篇 |
2019年 | 34篇 |
2018年 | 24篇 |
2017年 | 16篇 |
2016年 | 40篇 |
2015年 | 48篇 |
2014年 | 33篇 |
2013年 | 101篇 |
2012年 | 79篇 |
2011年 | 99篇 |
2010年 | 58篇 |
2009年 | 37篇 |
2008年 | 69篇 |
2007年 | 88篇 |
2006年 | 102篇 |
2005年 | 121篇 |
2004年 | 92篇 |
2003年 | 96篇 |
2002年 | 81篇 |
2001年 | 52篇 |
2000年 | 43篇 |
1999年 | 29篇 |
1998年 | 22篇 |
1997年 | 34篇 |
1996年 | 35篇 |
1995年 | 34篇 |
1994年 | 33篇 |
1993年 | 34篇 |
1992年 | 40篇 |
1991年 | 35篇 |
1990年 | 27篇 |
1989年 | 30篇 |
1988年 | 29篇 |
1987年 | 17篇 |
1986年 | 21篇 |
1985年 | 41篇 |
1984年 | 35篇 |
1983年 | 35篇 |
1982年 | 35篇 |
1981年 | 32篇 |
1980年 | 37篇 |
1979年 | 26篇 |
1978年 | 37篇 |
1977年 | 27篇 |
1976年 | 34篇 |
1975年 | 29篇 |
1974年 | 40篇 |
1973年 | 39篇 |
1972年 | 16篇 |
排序方式: 共有2405条查询结果,搜索用时 0 毫秒
11.
Bortoletto D Goldberg M Horwitz N Mestayer MD Moneti GC Sharma V Shipsey IP Skwarnicki T Csorna SE Letson T Brock IC Ferguson T Artuso M Bebek C Berkelman K Blucher E Byrd J Cassel DG Cheu E Coffman DM Crawford G DeSalvo R DeWire JW Drell PS Ehrlich R Galik RS Gittelman B Gray SW Halling AM Hartill DL Heltsley BK Kandaswamy J Kowalewski R Kreinick DL Kubota Y Lewis JD Mistry NB Mueller J Namjoshi R Nandi S Nordberg E O'Grady C Peterson D Pisharody M Riley D Sapper M Silverman A Stone S Worden H 《Physical review letters》1989,62(21):2436-2439
12.
Alam MS Katayama N Kim IJ Li WC Lou XC Sun CR Bortoletto D Goldberg M Horwitz N Mestayer MD Moneti GC Sharma V Shipsey IP Skwarnicki T Csorna SE Letson T Brock IC Ferguson T Artuso M Bebek C Berkelman K Blucher E Byrd J Cassel DG Cheu E Coffman DM Crawford G DeSalvo R DeWire JW Drell PS Ehrlich R Galik RS Gittelman B Gray SW Halling AM Hartill DL Heltsley BK Kandaswamy J Kowalewski R Kreinick DL Kubota Y Lewis JD Mistry NB Mueller J Namjoshi R Nandi S Nordberg E O'Grady C Peterson D Pisharody M 《Physical review D: Particles and fields》1989,40(11):3790
13.
M. Jonathan Fray Paul Allen Paul R. Bradley Clare E. Challenger Michael Closier Tim J. Evans Mark L. Lewis John P. Mathias Carly L. Nichols Yvonne M. Po-Ba Hayley Snow Mark H. Stefaniak Hannah V. Vuong 《Tetrahedron》2006,62(29):6869-6875
The synthesis of ten substituted aminomethylene tetrahydro-isoquinolines is described, proceeding in eight steps from 5-hydroxyisoquinoline via reductive amination of N-Boc tetrahydro-isoquinoline 5-carboxaldehyde. Likewise, reductive amination was used to prepare four substituted dihydro-isoindoles from the corresponding aldehyde. The dihydro-isoindole ring system was conveniently accessed via a 2+2+2 cycloaddition reaction. 相似文献
14.
Woodward C. A. Macinnis J. M. Lewis S. N. Greenbaum E. 《Applied biochemistry and biotechnology》1992,34(1):819-826
Applied Biochemistry and Biotechnology - Normal photosynthesis byCyanidium results in O2 evolution, suggesting that the uptake and subsequent reduction of CO2 also occur. This process, therefore,... 相似文献
15.
Alan D. Potoff Bertrand L. Chamberland Lewis Katz 《Journal of solid state chemistry》1973,8(3):234-237
A single crystal study of hydrothermally prepared eight-layer BaMnO3 has been carried out which confirms the (Zhdanov notation) 121121 layer stacking scheme for the BaO3 layers. The MnO6 octahedra share faces in strings of four, and these strings are connected to each other by corner sharing. The compound has an hexagonal unit cell of dimensions a = 5.667 ± 0.003 and c = 18.738 ± 0.009 Å, probable space group . Its structure has been determined from 352 independent reflections, of which 242 were considered observed, collected manually by a counter technique and refined to a conventional R value of 0.079. 相似文献
16.
17.
Twenty years of gibberellin research 总被引:4,自引:0,他引:4
Mander LN 《Natural product reports》2003,20(1):49-69
This review covers research into the chemistry and biology of the gibberellin family of plant bioregulators carried out in the author's laboratory over the past 20 years and has 231 references. 相似文献
18.
Brian F.G. Johnson Jack Lewis Martyn V. Twigg 《Journal of organometallic chemistry》1974,67(3):C75-C76
Photolysis of Ru3(CO)12 in the presence of donor ligands rapidly produces monomeric ruthenium species. 相似文献
19.
Wedin P Martinez CJ Lewis JA Daicic J Bergström L 《Journal of colloid and interface science》2004,272(1):1-9
Stress development during drying of coatings produced from aqueous dispersions of calcium carbonate particles in the presence and absence of organic binders was studied using a controlled-environment stress apparatus that simultaneously monitored drying stress, weight loss, and relative humidity. Specifically, the influence of two organic binders on drying stress evolution was investigated: (1) carboxymethylcellulose, a water-soluble viscosifying aid, and (2) a styrene-butadiene latex emulsion of varying glass transition temperature. The stress histories exhibited three distinct regions. First, a period of stress rise was observed, which reflected the capillary tension exerted by the liquid on the particle network. Second, a maximum stress was observed. Third, it was followed by a period of either stress decay or rise depending on the organic species present. Significant differences in stress histories were observed between coatings containing soluble and nonsoluble binders. Maximum drying stresses (sigmamax) of 0.2-0.5 MPa were observed for coatings produced from pure calcium carbonate or calcium carbonate-latex suspensions, whereas coatings with carboxymethylcellulose exhibited substantially higher sigmamax values of 1-2 MPa. Upon drying, these coatings were quite hygroscopic, such that cyclic variations in relative humidity induced large cyclic changes in residual stress. 相似文献
20.
Zareen Ahkter Andrew J. Edwards Scott L. Ingham Jack Lewis Ana M. Martin Castro Paul R. Raithby Gregory P. Shields 《Journal of Cluster Science》2000,11(1):217-226
The reaction of the di-gold cation [Au2(dppx)]2+ with the heptanuclear cluster dianion [Os7(CO)20]2– affords the mixed metal cluster [Os7(CO)20{Au2(dppx)}] (x=m (1), e (2), b (3)). On standing, in solution, this complex undergoes decarbonylation to give the cluster [Os7(CO)19{Au2(dppx)}] (x=m (4), e (5), b (6)). The complexes have been characterised spectroscopically, and an X-ray structure determination of the dppm derivative shows that it contains a metal core based on an Os7 edge-bridged bicapped tetrahedron with the two
3-Au atoms capping adjacent triangular Os3 faces of the central tetrahedron. In an analogous reaction, the carbido anion [Os7(H)C(CO)19]– affords the neutral cluster [Os7C(CO)19{Au2(dppm)}] (7) when treated with [Au2(dppm)]2+ in the presence of base. 相似文献