全文获取类型
收费全文 | 1750篇 |
免费 | 43篇 |
专业分类
化学 | 1261篇 |
晶体学 | 19篇 |
力学 | 31篇 |
数学 | 156篇 |
物理学 | 326篇 |
出版年
2022年 | 20篇 |
2021年 | 21篇 |
2020年 | 19篇 |
2019年 | 35篇 |
2018年 | 25篇 |
2017年 | 14篇 |
2016年 | 37篇 |
2015年 | 43篇 |
2014年 | 25篇 |
2013年 | 89篇 |
2012年 | 78篇 |
2011年 | 100篇 |
2010年 | 57篇 |
2009年 | 53篇 |
2008年 | 94篇 |
2007年 | 99篇 |
2006年 | 97篇 |
2005年 | 101篇 |
2004年 | 87篇 |
2003年 | 63篇 |
2002年 | 57篇 |
2001年 | 27篇 |
2000年 | 31篇 |
1999年 | 30篇 |
1998年 | 13篇 |
1997年 | 14篇 |
1996年 | 22篇 |
1995年 | 22篇 |
1994年 | 19篇 |
1993年 | 29篇 |
1992年 | 27篇 |
1991年 | 23篇 |
1990年 | 18篇 |
1989年 | 23篇 |
1988年 | 24篇 |
1987年 | 13篇 |
1986年 | 12篇 |
1985年 | 19篇 |
1984年 | 26篇 |
1983年 | 8篇 |
1982年 | 15篇 |
1981年 | 11篇 |
1980年 | 23篇 |
1979年 | 8篇 |
1978年 | 16篇 |
1977年 | 15篇 |
1976年 | 10篇 |
1975年 | 12篇 |
1974年 | 9篇 |
1973年 | 10篇 |
排序方式: 共有1793条查询结果,搜索用时 0 毫秒
11.
Ammar R Ball S Baringer P Bean A Besson D Coppage D Copty N Davis R Hancock N Kelly M Kwak N Lam H Kubota Y Lattery M Nelson JK Patton S Perticone D Poling R Savinov V Schrenk S Wang R Alam MS Kim IJ Nemati B O'Neill JJ Severini H Sun CR Zoeller MM Crawford G Daubenmier CM Fulton R Fujino D Gan KK Honscheid K Kagan H Kass R Lee J Malchow R Morrow F Skovpen Y Sung M White C Butler F Fu X Kalbfleisch G Ross WR Skubic P Snow J Wang PL Wood M Brown DN Fast J McIlwain RL Miao T Miller DH Modesitt M 《Physical review D: Particles and fields》1994,49(11):5701-5704
12.
13.
14.
15.
Cinabro D Henderson S Kinoshita K Liu T Saulnier M Wilson R Yamamoto H Sadoff AJ Ammar R Ball S Baringer P Coppage D Copty N Davis R Hancock N Kelly M Kwak N Lam H Kubota Y Lattery M Nelson JK Patton S Perticone D Poling R Savinov V Schrenk S Wang R Alam MS Kim IJ Nemati B O'Neill JJ Romero V Severini H Sun CR Zoeller MM Crawford G Fulton R Fujino D Gan KK Kagan H Kass R Lee J Malchow R Morrow F Skovpen Y Sung M White C Whitmore J Wilson P Butler F Fu X Kalbfleisch G Lambrecht M Ross WR 《Physical review letters》1993,70(24):3700-3704
16.
17.
Syntheses of 5-isopropyl-1,3-cyclohexadiene and syn-5-isopropyl-2,3-dioxabicyclo[2.2.2]octane, by routes that would allow completely diastereoselective introduction of deuterium labels, are described. The reaction of the isopropyl cyclohexadiene with singlet oxygen is shown to give an endoperoxide that is derived by preferential attack on the more sterically hindered face of the diene. A possible mechanistic explanation of this result is that the attack from the less hindered face leads to "ene" reaction rather than endoperoxide formation. However, this mechanism would require that the "ene" reaction and cycloaddition proceed via a common intermediate-presumably a perepoxide. 相似文献
18.
A high-performance liquid chromatographic method is described for the determination of terbutaline in human plasma in the range 1-35 ng/ml. Detection was achieved using a carbon fibre micro-electrochemical detector and a column-switching system. The microelectrode cell has advantages over conventional glassy carbon electrode-based detection systems in that it is easy to prepare, flexible in its operation and suffers less trouble from problems such as air bubbles and leaks. Furthermore, it has a better detection limit for terbutaline (0.8 ng/ml) to that obtained using a conventional glassy carbon electrode flow detector (2 ng/ml). Sample clean-up was by on-line solid-phase extraction with column switching, providing a method which was sensitive and reproducible, where the mean overall coefficient of variation was 5.60% and drug recovery in excess of 86% at the concentration levels studied. 相似文献
19.
Herein, we report a stereospecific E-olefin dipeptide isostere synthesis that can be used to make gram quantities of the Phe-Phe isostere desired for eliminating a specific backbone H-bond donor and acceptor in the Alzheimer's disease related Abeta peptide. The Phe19-Phe20 E-olefin analogue of Abeta(1-40) was prepared by solid-phase peptide synthesis and was subjected to amyloidogenesis conditions. This analogue can aggregate into spherical morphologies but does not progress on to form protofibrils or fibrils as is the case for the all-amide sequence, providing insight into the structural requirements for amyloidogenesis. 相似文献
20.
Shelby E. Thames Josef F. McClesky Phillip L. Kelly 《Journal of heterocyclic chemistry》1968,5(6):749-752
The preparation of several 2-furyl-, 2-thienyl-, benzyl-, and allylsubstituted silanes is reported. Such derivatives, when treated with aziridine in the presence of a metal catalyst, afford good yields of silylaziridines and silyldiaziridines. A qualitative study of electronic and steric requirements of the displacement reaction is reported. 相似文献