全文获取类型
收费全文 | 1863篇 |
免费 | 49篇 |
国内免费 | 10篇 |
专业分类
化学 | 1177篇 |
晶体学 | 14篇 |
力学 | 44篇 |
数学 | 258篇 |
物理学 | 429篇 |
出版年
2021年 | 12篇 |
2020年 | 17篇 |
2019年 | 25篇 |
2018年 | 18篇 |
2017年 | 13篇 |
2016年 | 27篇 |
2015年 | 29篇 |
2014年 | 26篇 |
2013年 | 89篇 |
2012年 | 86篇 |
2011年 | 90篇 |
2010年 | 46篇 |
2009年 | 43篇 |
2008年 | 82篇 |
2007年 | 101篇 |
2006年 | 86篇 |
2005年 | 56篇 |
2004年 | 57篇 |
2003年 | 59篇 |
2002年 | 62篇 |
2001年 | 47篇 |
2000年 | 34篇 |
1999年 | 19篇 |
1998年 | 26篇 |
1997年 | 32篇 |
1996年 | 25篇 |
1995年 | 28篇 |
1994年 | 26篇 |
1993年 | 34篇 |
1992年 | 23篇 |
1991年 | 18篇 |
1990年 | 22篇 |
1989年 | 23篇 |
1988年 | 23篇 |
1987年 | 34篇 |
1986年 | 33篇 |
1985年 | 43篇 |
1984年 | 39篇 |
1983年 | 25篇 |
1982年 | 37篇 |
1981年 | 19篇 |
1980年 | 18篇 |
1979年 | 14篇 |
1978年 | 23篇 |
1977年 | 14篇 |
1976年 | 24篇 |
1975年 | 21篇 |
1974年 | 30篇 |
1973年 | 20篇 |
1972年 | 14篇 |
排序方式: 共有1922条查询结果,搜索用时 31 毫秒
21.
Arikainen EO Boden N Bushby RJ Lozman OR Vinter JG Wood A 《Angewandte Chemie (International ed. in English)》2000,39(13):2333-2336
22.
M. Ebihara Y. S. Chung W. Chueinta B.-F. Ni T. Otoshi Y. Oura F. L. Santos F. Sasajima Sutisna A. K. B. H. Wood 《Journal of Radioanalytical and Nuclear Chemistry》2006,269(2):259-266
Summary Seven Asian countries have been collaborating in collecting airborne particulate matter (APM) in their individual countries
and analyzing them by neutron activation analysis as a common analytical tool. APM samples were collected into two fractions
of fine and coarse grains (PM2 and PM2-10, respectively). Analytical data were compared from several viewpoints such as particulate
sizes, locality of sampling sites (either urban or rural) and geographical location of participating countries. Chemical composition
and their monthly variations as well as mass concentrations appear to be highly characteristic for individual sampling sites,
suggesting that NAA data are suitable for evaluating the air quality in each site. 相似文献
23.
24.
Klein SR Himel TM Abrams G Amidei D Baden AR Barklow T Boyarski AM Boyer J Burchat PR Burke DL Butler F Dorfan JM Feldman GJ Gidal G Gladney L Gold MS Goldhaber G Golding L Haggerty J Hanson G Hayes K Herrup D Hollebeek RJ Innes WR Jaros JA Juricic I Kadyk JA Karlen D Lankford AJ Larsen RR LeClaire BW Levi M Lockyer NS Lüth V Matteuzzi C Nelson ME Ong RA Perl ML Petersen A Richter B Riles K Rowson PC Schaad T Schellman H Schmidke WB Sheldon PD Trilling GH de la Vaissiere C Wood DR Yelton JM 《Physical review letters》1987,58(7):644-647
25.
Gidal G Boyer J Butler F Cords D Abrams GS Amidei D Baden AR Barklow T Boyarski AM Burchat P Burke DL Dorfan JM Feldman GJ Gladney L Gold MS Goldhaber G Golding LJ Haggerty J Hanson G Hayes K Herrup D Hollebeek RJ Innes WR Jaros JA Juricic I Kadyk JA Karlen D Klein SR Lankford AJ Larsen RR LeClaire BW Levi ME Lockyer NS Lüth V Matteuzzi C Nelson ME Ong RA Perl ML Richter B Riles K Rowson PC Schaad T Schellman H Schmidke WB Sheldon PD Trilling GH de la Vaissière C Wood DR Yelton JM Zaiser C 《Physical review letters》1987,59(18):2016-2019
26.
S. F. Biagi M. Bourquin R. M. Brown H. J. Burckhart P. Extermann M. Gailloud C. N. P. Gee W. M. Gibson P. Jacot-Guillarmod J. Perrier K. J. Ragan Ph. Rosselet P. Schirato H. W. Siebert V. J. Smith K. P. Streit J. J. Thresher A. T. Wood C. Yanagisawa 《Zeitschrift fur Physik C Particles and Fields》1987,34(2):175-185
In an experiment at the CERN-SPS charged hyperon beam, we have investigated the inclusive \(\Lambda \bar K^0 \) and \(\Sigma ^0 \bar K^0 \) final states formed in Ξ? Be interactions. In the \(\Lambda \bar K^0 \) channel, we observe a signal at 1826 MeV/c2 which can be identified with the known Ξ(1820) resonance. We determine its mass and width to be:M=1826±4 MeV/c2, Г=12±14 MeV/c2. A moment analysis is consistent with a spin of 3/2 and indicates a negative parity for this spin assignment. Also in the \(\Lambda \bar K^0 \) channel, we observe a 3.6σ signal with the following parameters:M=1963±5 MeV/c2, Г=25±15 MeV/c2. This state, which we call Ξ(1960), is not observed in the \(\Sigma ^0 \bar K^0 \) channel, leading to an upper limit on the ratio of partial widths \(\Sigma \bar K/\Lambda \bar K\) of 2.3 (90% confidence level). A moment analysis of the \(\Lambda \bar K^0 \) final state indicates a spin of 5/2 or greater in the natural spin-parity series 5/2+, 7/2?, etc. 相似文献
27.
28.
Abachi S Baringer P Bylsma BG DeBonte R Koltick D Loeffler FJ Low EH McIlwain RL Miller DH Ng CR Rangan LK Shibata EI Derrick M Gan KK Kooijman P Loos JS Musgrave B Price LE Repond J Sugano K Weiss JM Wood DE Blockus D Brabson B Brom J Jung C Ogren H Rust DR Akerlof C Chapman J Errede D Kesten P Meyer DI Nitz D Seidl AA Thun R Willutzky M Cork B 《Physical review letters》1986,57(16):1990-1993
29.
Salma Kassem Alan T. L. Lee David A. Leigh Augustinas Markevicius Daniel J. Tetlow Naoyuki Toriumi 《Chemical science》2021,12(6):2065
Peptides attached to a cysteine hydrazide ‘transporter module’ are transported selectively in either direction between two chemically similar sites on a molecular platform, enabled by the discovery of new operating methods for a molecular transporter that functions through ratcheting. Substrate repositioning is achieved using a small-molecule robotic arm controlled by a protonation-mediated rotary switch and attachment/release dynamic covalent chemistry. A polar solvent mixtures were found to favour Z to E isomerization of the doubly-protonated switch, transporting cargo in one direction (arbitrarily defined as ‘forward’) in up to 85% yield, while polar solvent mixtures were unexpectedly found to favour E to Z isomerization enabling transport in the reverse (‘backward’) direction in >98% yield. Transport of the substrates proceeded in a matter of hours (compared to 6 days even for simple cargoes with the original system) without the peptides at any time dissociating from the machine nor exchanging with others in the bulk. Under the new operating conditions, key intermediates of the switch are sufficiently stabilized within the macrocycle formed between switch, arm, substrate and platform that they can be identified and structurally characterized by 1H NMR. The size of the peptide cargo has no significant effect on the rate or efficiency of transport in either direction. The new operating conditions allow detailed physical organic chemistry of the ratcheted transport mechanism to be uncovered, improve efficiency, and enable the transport of more complex cargoes than was previously possible.Peptides are transported in either direction between chemically similar sites on a molecular platform, substrate repositioning is achieved using a cysteine hydrazide transporter module and a small-molecule robotic arm controlled by a rotary switch. 相似文献
30.
Automated selective iodometric methods for the determination of chlorine and oxychlorine species have been developed for use in the drinking water industry. By utilising kinetic-based methods, linear ranges observed were: chlorine, 0.2–10 mg l?1; chlorine dioxide, 0.3–10 mg l?1; chlorite ion, 0.08–5 mg l?1; and chlorate ion, 0.08–5 mg l?1. 相似文献