全文获取类型
收费全文 | 232篇 |
免费 | 1篇 |
国内免费 | 5篇 |
专业分类
化学 | 122篇 |
晶体学 | 1篇 |
力学 | 2篇 |
数学 | 33篇 |
物理学 | 80篇 |
出版年
2021年 | 1篇 |
2017年 | 1篇 |
2016年 | 2篇 |
2015年 | 1篇 |
2014年 | 2篇 |
2013年 | 7篇 |
2012年 | 2篇 |
2011年 | 5篇 |
2010年 | 11篇 |
2009年 | 4篇 |
2008年 | 5篇 |
2007年 | 6篇 |
2006年 | 13篇 |
2005年 | 9篇 |
2004年 | 7篇 |
2003年 | 7篇 |
2002年 | 6篇 |
2001年 | 4篇 |
2000年 | 16篇 |
1999年 | 5篇 |
1998年 | 3篇 |
1997年 | 2篇 |
1996年 | 5篇 |
1995年 | 4篇 |
1994年 | 7篇 |
1993年 | 10篇 |
1992年 | 9篇 |
1991年 | 3篇 |
1990年 | 3篇 |
1989年 | 6篇 |
1988年 | 7篇 |
1987年 | 9篇 |
1986年 | 2篇 |
1985年 | 7篇 |
1984年 | 5篇 |
1983年 | 6篇 |
1982年 | 6篇 |
1981年 | 2篇 |
1980年 | 3篇 |
1978年 | 5篇 |
1977年 | 2篇 |
1976年 | 3篇 |
1975年 | 4篇 |
1974年 | 3篇 |
1973年 | 2篇 |
1972年 | 1篇 |
1970年 | 2篇 |
1969年 | 1篇 |
1968年 | 1篇 |
1887年 | 1篇 |
排序方式: 共有238条查询结果,搜索用时 15 毫秒
61.
Fujitani H Tanida Y Ito M Jayachandran G Snow CD Shirts MR Sorin EJ Pande VS 《The Journal of chemical physics》2005,123(8):084108
Direct calculations of the absolute free energies of binding for eight ligands to FKBP protein were performed using the Fujitsu BioServer massively parallel computer. Using the latest version of the general assisted model building with energy refinement (AMBER) force field for ligand model parameters and the Bennett acceptance ratio for computing free-energy differences, we obtained an excellent linear fit between the calculated and experimental binding free energies. The rms error from a linear fit is 0.4 kcal/mol for eight ligand complexes. In comparison with a previous study of the binding energies of these same eight ligand complexes, these results suggest that the use of improved model parameters can lead to more predictive binding estimates, and that these estimates can be obtained with significantly less computer time than previously thought. These findings make such direct methods more attractive for use in rational drug design. 相似文献
62.
Avery P Freyberger A Rodriguez J Yelton J Henderson S Kinoshita K Pipkin F Saulnier M Wilson R Wolinski J Xiao D Yamamoto H Sadoff AJ Ammar R Baringer P Coppage D Davis R Kelly M Kwak N Lam H Ro S Kubota Y Nelson JK Perticone D Poling R Schrenk S Alam MS Kim IJ Nemati B Romero V Sun CR Wang P Zoeller MM Crawford G Fulton R Gan KK Jensen T Kagan H Kass R Malchow R Morrow F Whitmore J Wilson P Butler F Fu X Kalbfleisch G Lambrecht M Skubic P Snow J Bortoletto D Brown DN Dominick J McIlwain RL 《Physical review letters》1992,68(9):1279-1282
63.
Dewey MS Gilliam DM Nico JS Wietfeldt FE Fei X Snow WM Greene GL Pauwels J Eykens R Lamberty A Van Gestel J 《Physical review letters》2003,91(15):152302
We report a new measurement of the neutron decay lifetime by the absolute counting of in-beam neutrons and their decay protons. Protons were confined in a quasi-Penning trap and counted with a silicon detector. The neutron beam fluence was measured by capture in a thin 6LiF foil detector with known absolute efficiency. The combination of these simultaneous measurements gives the neutron lifetime: tau(n)=(886.8+/-1.2[stat]+/-3.2[syst]) s. The systematic uncertainty is dominated by uncertainties in the mass of the 6LiF deposit and the 6Li(n,t) cross section. This is the most precise measurement of the neutron lifetime to date using an in-beam method. 相似文献
64.
ICP-AES法测定内蒙古地区六种沙生木本植物中金属元素 总被引:14,自引:5,他引:14
采用ICP-AES法分别对内蒙古地区梭梭、小叶锦鸡儿、沙冬青、红柳、沙枣和沙柳等六种沙生木本植物中金属元素进行了测定和分析。该方法的加标回收率为94.98%~120.25%,RSD<3.4%,具有良好的准确度和精密度。结果表明,常量元素Ca,K,Mg,Na,Al及植物生命活动所必需的微量元素Fe,Mn,Cu,Zn在六种沙生木本植物中表现为不同的含量顺序,且Fe,Mn,Cu,Zn四种元素的含量均低于陆生高等植物的平均含量。该测定结果为改善西部地区生态环境,选择优良防风固沙树种提供可靠的数据和理论依据。 相似文献
65.
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 Severini H Sun CR Zoeller MM Crawford G Daubenmeir M Fulton R Fujino D Gan KK Honscheid K 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 Skubic P Snow J Wang PL Wood M Bortoletto D Brown DN Fast J McIlwain RL 《Physical review letters》1993,71(5):674-678
66.
Selen M 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 Severini H Sun CR Zoeller MM Crawford G Daubenmeir 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 Whitmore J Wilson P Butler F Fu X Kalbfleisch G Lambrecht M Ross WR Skubic P Snow J Wang PL Wood M Bortoletto D Brown DN 《Physical review letters》1993,71(13):1973-1977
67.
We report a novel one-pot two-step synthesis of a variety of S-alkyl thiocarbamates. This method offers a two-directional approach making use of trichloroacetyl chloride, requires no complex starting material, incorporates a variety of substituents, and proceeds in high yields. 相似文献
68.
An efficient synthesis of phthalocyanines prepared from ortho-substituted phthalonitriles is described. The precursor to these phthalocyanines, 3-nitrophthalonitrile, is a key reagent for syntheses of phthalonitriles substituted at the 3-position by means of nucleophilic aromatic substitutions. An example of this type of phthalocyanine, prepared from 3-(4-cumylphenoxy)phthalonitrile, is compared with the phthalocyanine derived from 4-(4-cumylphenoxy)phthalonitrile. Substitution of the phthalocyanine at this more sterically crowded site causes a 20 nm bathochromic shift of the Q-band (π-π* transition). 相似文献
69.
A method using liquid chromatography-tandem mass spectrometry has been developed for determination of trace levels of tetracycline antibiotics in ground water and confined animal feeding operation waste water. Oxytetracycline (OTC), tetracycline (TC), and chlortetracycline (CTC) were extracted from water samples using both polymeric and C18 extraction cartridges. The addition of a buffer containing potassium phosphate and citric acid improved tetracycline recoveries in lagoon water. Method detection limits determined in reagent water fortified with 1 microg l(-1) OTC, TC, and CTC were 0.21, 0.20, and 0.28 microg l(-1). Method detection limits in lagoon water samples fortified at 20 microg l(-1) for OTC, TC, and CTC were 3.6, 3.1, and 3.8 microg l(-1). Variability in recovery from laboratory fortified blanks ranged from 86 to 110% during routine analysis. 相似文献
70.
Separation of a 1:1:1:1 calibration mixture of Aroclors 1221, 1016, 1254, and 1260 on soda glass capillaries coated with Apolane (C-87) or Apiezon L is described. Polychlorobiphenyl congener structures are assigned to 112 separated and partially separated zones. The quantitative composition of Aroclor 1221 is reported. The performance of the two stationary phases on different lengths of laboratory and commercially prepared capillaries is compared and found to be very similar. Aroclors 1221, 1016, 1254, and 1260 are employed (1:1:1:1) for the primary calibration mixture because they contain all components of the commercial materials which pollute the environment; they are also easily obtained from the U.S. EPA Repository so that the method can be used in any laboratory by employing the calibration data given here. 相似文献