全文获取类型
收费全文 | 1098篇 |
免费 | 47篇 |
国内免费 | 1篇 |
专业分类
化学 | 739篇 |
晶体学 | 7篇 |
力学 | 26篇 |
数学 | 229篇 |
物理学 | 145篇 |
出版年
2023年 | 5篇 |
2022年 | 11篇 |
2021年 | 14篇 |
2020年 | 16篇 |
2019年 | 22篇 |
2018年 | 20篇 |
2017年 | 21篇 |
2016年 | 40篇 |
2015年 | 43篇 |
2014年 | 44篇 |
2013年 | 52篇 |
2012年 | 90篇 |
2011年 | 75篇 |
2010年 | 53篇 |
2009年 | 39篇 |
2008年 | 74篇 |
2007年 | 81篇 |
2006年 | 72篇 |
2005年 | 68篇 |
2004年 | 38篇 |
2003年 | 26篇 |
2002年 | 32篇 |
2001年 | 14篇 |
2000年 | 16篇 |
1999年 | 14篇 |
1998年 | 9篇 |
1997年 | 9篇 |
1996年 | 9篇 |
1995年 | 7篇 |
1994年 | 12篇 |
1993年 | 7篇 |
1992年 | 4篇 |
1991年 | 4篇 |
1990年 | 4篇 |
1989年 | 6篇 |
1988年 | 10篇 |
1986年 | 4篇 |
1985年 | 10篇 |
1984年 | 9篇 |
1983年 | 7篇 |
1982年 | 5篇 |
1981年 | 11篇 |
1980年 | 4篇 |
1978年 | 4篇 |
1976年 | 6篇 |
1975年 | 7篇 |
1974年 | 3篇 |
1973年 | 2篇 |
1968年 | 3篇 |
1927年 | 2篇 |
排序方式: 共有1146条查询结果,搜索用时 0 毫秒
61.
62.
In a study of the solid-state reactions in the ternary systems TeO2? MoO3? MoO2 and TeO2? MoO3? Te, approximately 70 selected compositions were sintered at 550°C to attain equilibrium conditions, and solid-state equilibrium relations were characterized by x-ray diffraction. In a large composition range, the interaction of TeO2 and MoO3 with the reducing agents MoO2 or Te leads to the reduced ternary oxide TeMo4O13 (m. p. 748°C), in addition to Te2MoO7, Te and (intermediate) molybdenum oxides. The compatibility relations for the binary systems TeO2? MoO2 and MoO3? Te are presented for the first time. In the TeO2? MoO2 system, three-phase regions are found: (Te2MoO7? TeO2? Te) on the TeO2? and (TeMo4O13? MoO2? Te) on the MoO2-rich sides with (TeMo4O13? Te2MoO7? Te) in the intermediate region. In the MoO3? Te system, three-phase regions (TeMo4O13? MoO2? Te), (TeMo4O13? Mo4O11? MoO2) and (TeMo4O13? MoO3? Mo4O11) were detected. TeMo4O13 presents two allotropic forms (α′ for T < 450°C, α for T > 450°C). Both structures have been characterized by I.R. and optical reflectance spectroscopy. Unit cell dimensions are also given. 相似文献
63.
Cristiano A Lim CW Rozkiewicz DI Reinhoudt DN Ravoo BJ 《Langmuir : the ACS journal of surfaces and colloids》2007,23(17):8944-8949
This paper describes the adsorption and spreading of beta-cyclodextrin (CD) vesicles on hydrophobic and hydrophilic substrates, which involves a transition from bilayer vesicles to planar molecular monolayers or bilayers. On substrates that are patterned with self-assembled monolayers by microcontact printing (muCP), the CD vesicles preferentially adsorb on hydrophobic areas instead of hydrophilic (nonionic) areas, and on cationic areas instead of hydrophilic (nonionic) areas. Supported monolayers of amphiphilic cyclodextrins CD1 and CD2 were obtained by adsorption of CD vesicles to hydrophobic substrates, and supported bilayers of amphiphilic cyclodextrins CD1 and CD2 were prepared by adsorption of CD vesicles on cationic substrates. Contact angle goniometry, atomic force microscopy and confocal fluorescence microscopy (CFM) were used to analyze the supported CD layers. The fluidity of the supported CD layers was verified using fluorescence recovery after photobleaching experiments. The supported layers function as a supramolecular platform that can bind suitable guest molecules through inclusion in the CD host cavities. Additionally, the CD host layers were patterned with fluorescent guest molecules by supramolecular muCP on the supported CD layers. The host-guest interactions were investigated with CFM and fluorescence resonance energy transfer experiments. 相似文献
64.
Affinity capillary electrophoresis to evaluate the complex formation between poliovirus and nanobodies 下载免费PDF全文
Hadewych Halewyck Lise Schotte Iuliana Oita Bert Thys Ann Van Eeckhaut Yvan Vander Heyden Bart Rombaut 《Journal of separation science》2014,37(24):3729-3737
It was demonstrated that nanobodies with an in vitro neutralizing activity against poliovirus type 1 interact with native virions. Here, the use of capillary electrophoresis was investigated as an alternative technique for the evaluation of the formation of nanobody–poliovirus complexes, and therefore predicting the in vitro neutralizing activity of the nanobodies. The macromolecules are preincubated offline in a specific nanobody‐to‐virus ratio and analyzed by capillary electrophoresis with UV detection. At low nanobody‐to‐virus ratios, a clear shift in migration time of the viral peak was observed. A broad peak was obtained, indicating the presence of a heterogeneous population of nanobody–virion complexes, caused by the binding of different numbers of nanobodies to the virus particle. At elevated nanobody‐to‐virus ratios, a cluster of peaks appeared, showing an additional increase in migration times. It was shown that, at these high molar excesses, aggregates were formed. The developed capillary electrophoresis method can be used as a rapid, qualitative screening for the affinity between poliovirus and nanobodies, based on a clearly visible and measurable shift in migration time. The advantages of this technique include that there is no need for antigen immobilization as in enzyme‐linked immunosorbent assays or surface plasmon resonance for the use of radiolabeled virus or for the performance of labor‐ and time‐intensive plaque‐forming neutralization assays. 相似文献
65.
66.
Maurice J. Ahsman Bart C. van der Nagel Ron A. Mathot 《Biomedical chromatography : BMC》2010,24(9):969-976
Currently, pharmacokinetic–pharmacodynamic studies of sedatives and analgesics are performed in neonates and children to find suitable dose regimens. As a result, sensitive assays using only small volumes of blood are necessary to determine drug and metabolite concentrations. We developed an ultra‐performance liquid chromatographic method with tandem mass spectrometry detection for quantification of midazolam, 1‐hydroxymidazolam, hydroxymidazolamglucuronide, morphine, morphine‐3‐glucuronide and morphine‐6‐glucuronide in 100 μL of plasma. Cleanup consisted of 96 wells micro‐solid phase extraction, before reversed‐phase chromatographic separation (ultra‐performance liquid chromatography) and selective detection using electrospray ionization tandem mass spectrometry. Separate solid‐phase extraction methods were necessary to quantify morphine, midazolam and their metabolites because of each group's physicochemical properties. Standard curves were linear over a large dynamic range with adequate limits of quantitation. Intra‐ and interrun accuracy and precision were within 85–115% (of nominal concentration using a fresh calibration curve) and 15% (coefficient of variation, CV) respectively. Recoveries were >80% for all analytes, with interbatch CVs (as a measure of matrix effects) of less than 15% over six batches of plasma. Stability in plasma and extracts was sufficient, allowing large autosampler loads. Runtime was 3.00 min per sample for each method. The combination of 96‐well micro‐SPE and UPLC‐MS/MS allows reliable quantification of morphine, midazolam and their major metabolites in 100 μL of plasma. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
67.
Phase transitions of [M(H2O)6](MnO4)2, where M=Mg, Ni, Zn and Cd, have been studied at 100–400 K by differential scanning calorimetry (DSC). One solid–solid phase transition for the compounds with M=Mg and Ni and two solid–solid phase transitions for these with M=Zn and Cd have been discovered. Additionally, three phase transitions, connected with three-stage melting process of these compounds, were also found. Thermodynamic parameters of the all detected phase transitions were calculated. 相似文献
68.
The study of theacidic sites in zeolites is important to understand the nature of the acidic catalyticfunction.…… 《催化学报》2001,22(3):219-220
The study of the acidic sites in zeolites is important to understand the nature of the acidic catalytic function. 相似文献
69.
Donohue R Mazzaglia A Ravoo BJ Darcy R 《Chemical communications (Cambridge, England)》2002,(23):2864-2865
Cationic amphiphilic beta-cyclodextrins, substituted with hydrophobic n-alkylthio chains at the primary hydroxyl side and hydrophilic omega-amino-oligo(ethylene glycol) units at the secondary side, form bilayer vesicles with a diameter of 30-35 nm (when alkyl = hexadecyl) or nanoparticles with a diameter of ca. 120 nm (when alkyl = hexyl) in water. 相似文献
70.
Drent E van Dijk R van Ginkel R van Oort B Pugh RI 《Chemical communications (Cambridge, England)》2002,(7):744-745
Copolymerisation of ethene and alkylacrylates is catalysed by palladium modified with di(2-methoxyphenyl)phosphinobenzene-2-sulfonic acid (DOPPBS); a linear polymer is produced in which acrylate units are incorporated into the polyethylene backbone. 相似文献