全文获取类型
收费全文 | 1191篇 |
免费 | 31篇 |
国内免费 | 11篇 |
专业分类
化学 | 740篇 |
晶体学 | 7篇 |
力学 | 9篇 |
数学 | 90篇 |
物理学 | 387篇 |
出版年
2022年 | 8篇 |
2021年 | 11篇 |
2020年 | 14篇 |
2019年 | 12篇 |
2018年 | 7篇 |
2017年 | 8篇 |
2016年 | 22篇 |
2015年 | 23篇 |
2014年 | 22篇 |
2013年 | 45篇 |
2012年 | 72篇 |
2011年 | 62篇 |
2010年 | 48篇 |
2009年 | 65篇 |
2008年 | 62篇 |
2007年 | 61篇 |
2006年 | 60篇 |
2005年 | 56篇 |
2004年 | 44篇 |
2003年 | 40篇 |
2002年 | 49篇 |
2001年 | 35篇 |
2000年 | 38篇 |
1999年 | 12篇 |
1998年 | 17篇 |
1997年 | 13篇 |
1996年 | 19篇 |
1995年 | 18篇 |
1994年 | 24篇 |
1993年 | 9篇 |
1992年 | 12篇 |
1990年 | 9篇 |
1989年 | 14篇 |
1988年 | 16篇 |
1987年 | 12篇 |
1986年 | 10篇 |
1985年 | 23篇 |
1984年 | 10篇 |
1983年 | 11篇 |
1982年 | 8篇 |
1981年 | 12篇 |
1980年 | 6篇 |
1979年 | 12篇 |
1978年 | 9篇 |
1977年 | 6篇 |
1976年 | 7篇 |
1975年 | 9篇 |
1974年 | 8篇 |
1973年 | 9篇 |
1972年 | 13篇 |
排序方式: 共有1233条查询结果,搜索用时 15 毫秒
911.
W. Esty R. Gillette M. Hamilton D. Taylor 《Annals of the Institute of Statistical Mathematics》1985,37(1):109-129
Summary Derivatives of statistical functionals have been used to derive the asymptotic distributions ofL-,M- andR-estimators. This approach is often heuristic because the types of derivatives chosen have serious limitations. The Gateaux
derivative is too weak and the Fréchet derivative is too strong. In between lies the compact derivative. This paper obtains
strong results in a rigorous manner using the compact derivative onC
0(R). This choice of space allows results for a broader class of functionals than previous choices, and the fact that
is often tight provides the compact set required. A major result is the derivation of the compact derivative of the inverse
c.d.f. when the range space is endowed with the uniform norm. It has applications to the asymptotic theory ofL-,M- andR-estimators. We illustrate the power of this result by applications toL-estimators in settings including the one sample problem, data grouped by quantiles, and censored survival time data. 相似文献
912.
Baltrusaitis RM Becker JJ Blaylock GT Brown JS Bunnell KO Burnett TH Cassell RE Coffman D Cook V Coward DH Dado S Del Papa C Dorfan DE Dubois GP Duncan AL Einsweiler KF Eisenstein BI Fabrizio R Gladding G Grancagnolo F Hamilton RP Hauser J Heusch CA Hitlin DG Koepke L Lockman WS Mockett PM Moss L Mozley RF Nappi A Odian A Partridge R Perrier J Plaetzer SA Richman JD Roehrig JR Russell JJ Sadrozinski HF Scarlatella M Schalk TL Schindler RH Seiden A Sleeman JC Spadafora AL Thaler JJ Toki W 《Physical review letters》1985,54(18):1976-1979
913.
José S. Casas Félix Condori Umberto Russo José Sordo José M. Varela 《Journal of organometallic chemistry》2004,689(3):620-626
The reactions of dimethyl-, diethyl- and dibutyltin(IV) oxides with pyridoxine (PN) in toluene/ethanol led to the formation of compounds [SnR2(PN-2H)] which were characterized by EI and FAB mass spectrometry and by IR, Raman, Mössbauer and 1H, 13C and 119Sn NMR spectroscopy. The structures of [SnEt2(PN-2H)] · CH3OH, [SnBu2(PN-2H)] and [SnEt2(PN-2H)(DMSO)] were determined by X-ray diffractometry. The first two contain dimeric [SnR2(PN-2H)]2 units in which two bridging-chelating pyridoxinate anions link the Sn atoms, while in [SnEt2(PN-2H)(DMSO)] the DMSO coordinates to the tin atom via its O atom in a similar dimeric unit. 相似文献
914.
Keith R. Hornberger George M. Adjabeng Hamilton D. Dickson Ronda G. Davis-Ward 《Tetrahedron letters》2006,47(30):5359-5361
A one-pot synthesis of disubstituted benzimidazoles from 2-nitroanilines is described. Hydrogenation of N-substituted 2-nitroanilines with palladium on carbon as catalyst in the presence of trimethyl orthoformate and catalytic pyridinium p-toluenesulfonate (PPTS) at room temperature provided good to excellent yields of the corresponding disubstituted benzimidazoles. 相似文献
915.
We establish in this work sufficient conditions for the existence of periodic solutions for the Liénard equation
. 相似文献
916.
917.
918.
919.
Shore SG Hamilton EJ Bridges AN Bausch J Krause-Bauer JA Dou D Liu J Liu S Du B Hall H Meyers EA Vermillion KE 《Inorganic chemistry》2003,42(4):1175-1186
The structure of [PPh(3)(benzyl)][B(10)H(11)] was determined at -123 degrees C and 24 degrees C by single-crystal X-ray analyses. The B(10) core of [B(10)H(11)](-) is similar in shape to that of [B(10)H(10)](2)(-). The 11th H atom asymmetrically caps a polar face of the cluster and shows no tendency for disorder in the solid state. Variable temperature multinuclear NMR studies shed light on the dynamic nature of [B(10)H(11)](-) in solution. In addition to the fluxionality of the cluster H atoms, the boron cage is fluxional at moderate temperatures, in contrast to [B(10)H(10)](2)(-). Multiple exchange processes are believed to take place as a function of temperature. Results of ab initio calculations are presented. Crystal data: [PPh(3)(benzyl)][B(10)H(11)] at -123 degrees C, P2(1)/c, a = 9.988(2) A, b = 18.860(2) A, c = 15.072(2) A, beta = 107.916(8) degrees, V = 2701.5(7) A(3), Z = 4; [PPh(3)(benzyl)][B(10)H(11)] at 24 degrees C, P2(1)/c, a = 10.067(5) A, b = 19.009(9) A, c = 15.247(7) A, beta = 107.952(9) degrees, V = 2775(2) A(3), Z = 4. 相似文献
920.
Bench BJ Johnson R Hamilton C Gooch J Wright JR 《Journal of colloid and interface science》2004,270(2):315-320
It has been shown in preliminary studies that the antibacterial protein avidin self-associates with the boric acid gel polymer, and avidin-coated gel particles in the micrometer and submicrometer size ranges are of interest for boron neutron-capture therapy (BNCT), which is neutron-induced fission of boron-10 to produce intense alpha radiation for tumor destruction. The gel particles carry large amounts of boron-10 and are theoretically able effect a meaningful tissue dosing through BNCT. A gross precipitation of gel particles occurs within 46 min of mixing when the avidin/colloid ratio is about 0.34 g avidin/g colloid. This is a minimum time if gel and avidin concentrations are in the low microgram/milliliter range, but at higher proportions of avidin the time delay to precipitation increases significantly; i.e., the colloid surface becomes blocked, inhibiting lattice formation. The avidin-coated gel particles eventually cross-link, forming a solid matrix and precipitating on a timescale measured on the order of an hour. At shorter exposure times rapid agglutination-like reactions were observed with biotinylated bovine albumin, suggesting that two-stage pretargeting of specific tissues should be possible with biotinylated antitumor antibodies. However, for BNCT to be practical, avidin's interaction with the gel needs to be strengthened, and all aryl-B(OH)(2) groups on the particle surfaces must be blocked, or else the particles will interact strongly and nonspecifically with each other and with the carbohydrate groups present on most cell surfaces. Glyceric acid delays the precipitation of the particle suspensions while most simple and complex carbohydrates accelerate it. 相似文献