全文获取类型
收费全文 | 699篇 |
免费 | 24篇 |
国内免费 | 3篇 |
专业分类
化学 | 398篇 |
晶体学 | 5篇 |
力学 | 9篇 |
数学 | 48篇 |
物理学 | 266篇 |
出版年
2023年 | 2篇 |
2022年 | 4篇 |
2021年 | 14篇 |
2020年 | 9篇 |
2019年 | 13篇 |
2018年 | 13篇 |
2017年 | 11篇 |
2016年 | 26篇 |
2015年 | 18篇 |
2014年 | 14篇 |
2013年 | 32篇 |
2012年 | 35篇 |
2011年 | 40篇 |
2010年 | 23篇 |
2009年 | 20篇 |
2008年 | 32篇 |
2007年 | 33篇 |
2006年 | 19篇 |
2005年 | 25篇 |
2004年 | 23篇 |
2003年 | 22篇 |
2002年 | 27篇 |
2001年 | 16篇 |
2000年 | 30篇 |
1999年 | 12篇 |
1998年 | 6篇 |
1997年 | 10篇 |
1996年 | 16篇 |
1995年 | 7篇 |
1994年 | 21篇 |
1993年 | 20篇 |
1992年 | 18篇 |
1991年 | 8篇 |
1990年 | 20篇 |
1989年 | 10篇 |
1988年 | 15篇 |
1987年 | 13篇 |
1986年 | 10篇 |
1985年 | 5篇 |
1983年 | 4篇 |
1982年 | 5篇 |
1981年 | 5篇 |
1979年 | 4篇 |
1978年 | 2篇 |
1976年 | 4篇 |
1974年 | 2篇 |
1973年 | 2篇 |
1970年 | 1篇 |
1969年 | 1篇 |
1935年 | 1篇 |
排序方式: 共有726条查询结果,搜索用时 31 毫秒
31.
The adaptation of a Du Pont Thermogravimetric Analyser for the measurement of magnetic susceptibility as a function of temperature in the range – 80 °C to 300 °C is described.
Zusammenfassung Die Adaptation des Du Pont's Thermogravimetric Analyzer zur Messung der magnetischen Suszeptibilität in Abhängigkeit von der Temperatur im Bereich von – 80° bis 300 °C wird mitgeteilt.
–80°–300 °.相似文献
32.
J. Gomez C. Bruneau N. Soyer A. Brault 《Journal of Analytical and Applied Pyrolysis》1985,7(4):307-313
The pyrolysis of amphetamine sulphate was studied in a laboratory flow reactor in the range 350–1000°C. The identifications and quantitative determinations of most gaseous and condensed products by means of gas chromatography and mass spectrometry made possible the suggestion of a thermal degradation scheme. The presence of sulphate in the initial molecule led to oxidation reactions in addition to the usual thermal reactions that occur during the pyrolysis of organic materials. 相似文献
33.
de Farias RF de Souza JM de Melo JV Airoldi C 《Journal of colloid and interface science》1999,212(1):123-129
The effects exhibited by adsorbed conducting polyaniline on the redox process on a molybdenum oxide surface were studied. Thermogravimetric results indicate a 4% polyaniline deposition. Cyclic voltammograms of the adsorbed polymer on MoO3 show that polyaniline exerts remarkable effects on the molybdenum blue oxidation-reduction process, with oxidation and reduction potentials of 0.33 and 0.18 V, respectively. This effect strongly enhances the electrode response, and can be used as an important tool in qualitative and/or quantitative determinations of molybdenum in solution as well as in any substrate. Copyright 1999 Academic Press. 相似文献
34.
J. Martinez Calatayud S. Navasquillo Sarrion A. Sanchez Sampedro C. Gomez Benito 《Microchemical Journal》1992,45(2)
A flow injection analysis procedure for the turbidimetric determination of promethazine is proposed. The sample solution is injected directly into the carrier reagent stream, which is composed of 1.16 × 10−3M bromophenol blue at pH 1.20. The calibration graph is linear over the range 25–197 ppm of promethazine. The influence of some foreign substances was also investigated. The method is applied to promethazine determination in a pharmaceutical formulation. 相似文献
35.
Schumm BA Koetke DS Adolphsen CE Alexander JP Averill D Barish BC Barklow T Barnett BA Blockus D Boyarski A Brabson B Breakstone A Bulos F Burchat PR Burke DL Cence RJ Chapman J Chmeissani M Cords D Coupal DP Dauncey P DeStaebler HC Dorfan JM Drell PS Drewer DC Durrett D Elia R Feldman GJ Field RC Ford WT Fordham C Frey R Fujino D Gan KK Gero E Gidal G Glanzman T Goldhaber G Gomez Cadenas JJ Gratta G Hanson G Harr R Harral B Harris FA Hayes K Hearty C Heusch CA Hildreth MD Himel T Hinshaw DA 《Physical review D: Particles and fields》1992,46(1):453-456
36.
37.
This work describes the use of a dual-standard analysis approach termed the time-average ratio (TAR) in affinity capillary electrophoresis (ACE) to estimate binding constants of receptors to ligands. In this form of analysis the TAR is the migration time of the receptor divided by the average of the sum of the migration times of two non-interacting standards. This change in TAR as a function of the concentration of ligand yields a value for the binding constant. This concept is demonstrated using three model systems: carbonic anhydrase B (CAB, EC 4.2.1.1) and arylsulfonamides, vancomycin (Van) and ristocetin (Rist) from Streptomyces orientalis and Nocardia lurida, respectively, and d-Ala- d-Ala terminus peptides. Three ACE techniques are used to examine the three systems: standard ACE, flow-through partial-filling ACE (FTPFACE), and on-column derivatization coupled to ACE. The findings described here demonstrate that ACE data analyzed using the TAR form of analysis yield binding constants between receptors and ligands comparable to those estimated using other ACE forms of analysis. A comparison to three other forms of analysis is described. 相似文献
38.
Isabel Pizarro Ma Milagros Gomez Carmen Cámara Ma Antonia Palacios 《International journal of environmental analytical chemistry》2013,93(10):879-890
Gradient ion chromatographic separation coupled with ICP-MS was used to resolve and determine the most common arsenic species in environmental and biological samples of carrots, trout, soil, sediment and river water from Region II of Chile. The carrot and trout samples showed a concentration of 49 and 168 µg g?1, respectively, of total As. Both concentrations are high considering the basal level. In the carrots, percentage of 45 and 31% of total As were found for As(III) and As(V) species, respectively. In the trout, the higher concentration related to AsB at 39% of the total As. As(III) and DMA were also present in relatively high concentrations. The River Loa and the soil in which the carrots are growing also present very high As(V) concentrations of 100 and 17 µg g?1, respectively. The ratio between the concentration for the same As species found in the living organisms (carrots and trout) and the environment in which they grow (soil and water) can provide important information about the possible absorption or biotransformation of As species in living beings. As(III) and DMA are the species in which the greatest accumulation occurs with respect to the medium in which they are present, and biotransformation also appears to take place. 相似文献
39.
40.