全文获取类型
收费全文 | 663篇 |
免费 | 16篇 |
国内免费 | 3篇 |
专业分类
化学 | 508篇 |
晶体学 | 6篇 |
力学 | 6篇 |
数学 | 109篇 |
物理学 | 53篇 |
出版年
2023年 | 2篇 |
2022年 | 8篇 |
2021年 | 8篇 |
2020年 | 12篇 |
2019年 | 14篇 |
2018年 | 6篇 |
2017年 | 9篇 |
2016年 | 10篇 |
2015年 | 16篇 |
2014年 | 15篇 |
2013年 | 30篇 |
2012年 | 31篇 |
2011年 | 44篇 |
2010年 | 25篇 |
2009年 | 25篇 |
2008年 | 40篇 |
2007年 | 38篇 |
2006年 | 33篇 |
2005年 | 37篇 |
2004年 | 27篇 |
2003年 | 28篇 |
2002年 | 35篇 |
2001年 | 11篇 |
2000年 | 13篇 |
1999年 | 5篇 |
1998年 | 8篇 |
1997年 | 10篇 |
1996年 | 19篇 |
1995年 | 5篇 |
1994年 | 4篇 |
1993年 | 10篇 |
1992年 | 6篇 |
1991年 | 5篇 |
1990年 | 6篇 |
1989年 | 6篇 |
1987年 | 5篇 |
1986年 | 7篇 |
1985年 | 12篇 |
1984年 | 2篇 |
1983年 | 4篇 |
1982年 | 7篇 |
1981年 | 9篇 |
1980年 | 8篇 |
1978年 | 6篇 |
1977年 | 6篇 |
1976年 | 6篇 |
1973年 | 4篇 |
1971年 | 1篇 |
1970年 | 1篇 |
1966年 | 1篇 |
排序方式: 共有682条查询结果,搜索用时 15 毫秒
661.
It is well known that every scalar convex function is locally Lipschitz on the interior of its domain in finite dimensional spaces. The aim of this paper is to extend this result for both vector functions and set-valued mappings acting between infinite dimensional spaces with an order generated by a proper convex cone C. Under the additional assumption that the ordering cone C is normal, we prove that a locally C-bounded C-convex vector function is Lipschitz on the interior of its domain by two different ways. Moreover, we derive necessary conditions for Pareto minimal points of vector-valued optimization problems where the objective function is C-convex and C-bounded. Corresponding results are derived for set-valued optimization problems. 相似文献
662.
Turega SM Lorenz C Sadownik JW Philp D 《Chemical communications (Cambridge, England)》2008,(34):4076-4078
Nitrones undergo dynamic exchange in chloroform at room temperature through two mechanisms-hydrolysis and recombination or hydroxylamine addition/elimination; this dynamic exchange is harnessed to select a nitrone-based bis(amidopyridine) receptor for diacids from a group of four nitrones through its binding to a glutaric acid-based target. 相似文献
663.
Agmo Hernández V Niessen J Harnisch F Block S Greinacher A Kroemer HK Helm CA Scholz F 《Bioelectrochemistry (Amsterdam, Netherlands)》2008,74(1):210-216
The interaction of thrombocyte vesicles with the surface of metal electrodes, i.e., mercury, gold and gold electrodes modified with self assembled monolayers (SAM), was studied with the help of chronoamperometry, atomic force microscopy, and quartz crystal microbalance measurements. The experimental results show that the interaction of the thrombocyte vesicles with the surface of the electrodes depends on the hydrophobicity of the latter: whereas on very hydrophobic surfaces (mercury and gold functionalized with SAM) the thrombocyte vesicles disintegrate and form a monolayer of lipids, on the less hydrophobic gold surface a bilayer is formed. The chronoamperometric measurements indicate the possibility of future applications to probe membrane properties of thrombocytes. 相似文献
664.
Martins-de-Souza D Gattaz WF Schmitt A Rewerts C Maccarrone G Dias-Neto E Turck CW 《Journal of separation science》2008,31(16-17):3122-3126
The prefrontal cortex executes important functions such as differentiation of conflicting thoughts, correct social behavior and personality expression, and is directly implicated in different neurodegenerative diseases. We performed a shotgun proteome analysis that included IEF fractionation, RP-LC, and MALDI-TOF/TOF mass spectrometric analysis of tryptic digests from a pool of seven human dorsolateral prefrontal cortex protein extracts. In this report, we present a catalog of 387 proteins expressed in these samples, identified by two or more peptides and high confidence search scores. These proteins are involved in different biological processes such as cell growth and/or maintenance, metabolism/energy pathways, cell communication/signal transduction, protein metabolism, transport, regulation of nucleobase, nucleoside, nucleotide and nucleic acid metabolism, and immune response. This analysis contributes to the knowledge of the human brain proteome by adding sample diversity and protein expression data from an alternative technical approach. It will also aid comparative studies of different brain areas and medical conditions, with future applications in basic and clinical research. 相似文献
665.
Jung C 《Analytical and bioanalytical chemistry》2008,392(6):1031-1058
Cytochrome P450 proteins (CYPs) are a big class of heme proteins which are involved in various metabolic processes of living
organisms. CYPs are the terminal catalytically active components of monooxygenase systems where the substrate binds and is
hydroxylated. In order to be functionally competent, the protein structures of CYPs possess specific properties that must
be explored in order to understand structure–function relationships and mechanistic aspects. Fourier transform infrared spectroscopy
(FTIR) is one tool that is used to study these structural properties. The application of FTIR spectroscopy to the secondary
structures of CYP proteins, protein unfolding, protein–protein interactions and the structure and dynamics of the CYP heme
pocket is reviewed. A comparison with other thiolate heme proteins (nitric oxide synthase and chloroperoxidase) is also included.
Figure The protein secondary structure, protein unfolding, redox-partner protein–protein interaction, structural changes induced
by the reduction of the heme iron, and the structure and dynamics of the active site of cytochromes P450 (CYP) can be studied
using Fourier transform infrared spectroscopy (FTIR). FTIR spectroscopy is a good approach for gaining a deeper insight into
structure–function relationships in CYPs.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
666.
Deng S Schwarzmaier C Eichhorn C Scherer O Wolmershäuser G Zabel M Scheer M 《Chemical communications (Cambridge, England)》2008,(34):4064-4066
A novel 1,2,3-triphosphaferrocene has been synthesised, which reacts with CuBr to give a 2D polymer, revealing an unprecedented pi-stacking of the triphospholyl moieties. 相似文献
667.
Bouza Gemayqzel Quintana Ernest Tammer Christiane 《Journal of Optimization Theory and Applications》2021,190(3):711-743
Journal of Optimization Theory and Applications - In this paper, we study a first-order solution method for a particular class of set optimization problems where the solution concept is given by... 相似文献
668.
669.
670.
Redondo AH Körber C König S Längin A Al-Ahmad A Weinmann W 《Analytical and bioanalytical chemistry》2012,402(7):2417-2424
Ethyl glucuronide (EtG) and ethyl sulfate (EtS) are direct alcohol consumption markers widely used nowadays for clinical and
forensic applications. They are detectable in blood and urine even after consumption of trace amounts of ethanol and for a
longer time frame, being detectable even when no more ethanol is present. The instability of EtG against bacterial degradation
in contaminated urine samples and/or the possible postcollection synthesis of this metabolite in samples containing, e.g.,
Escherichia coli and ethanol, may cause false identification of alcohol uptake. Therefore, it is of paramount importance to constrict these
error sources by inhibition of any bacterial growth causing hydrolization or synthesis of EtG. This study evaluates a new
method of collecting urine samples on filter paper, dried urine spots (DUS), for simultaneous detection of EtG, EtS and creatinine,
having the great advantage of inhibiting bacterial activity. In addition, a method validation for the determination of EtG
and EtS in DUS was performed according to the FDA guidelines. Sterile-filtered urine was spiked with EtG and EtS, inoculated
with E. coli and incubated. Liquid and dried urine samples were collected after various time intervals up to 96 h. Liquid samples were
frozen immediately after collection, whereas aliquots for DUS were pipetted onto filter paper, allowed to dry and stored at
RT until analysis 1 week after. The specimens were analyzed by LC–ESI–MS/MS. As expected, degradation of EtG, but not of EtS,
was observed in contaminated liquid urine samples. However, the specimens collected on filter paper and stored at RT showed
no degradation during storage. Therefore, collecting urine samples on filter paper for EtG and EtS analysis turns out to be
a reliable method to avoid bacterial degradation of EtG and EtS, and consequently, stabilization of these ethanol metabolites
is achieved. In addition, simultaneous measurement of creatinine content as an indicator of urine dilution helps to interpret
the results. Method validation for EtG and EtS in DUS was satisfactory, showing the linearity of the calibration curves in
the studied concentration range, good precision, accuracy and selectivity. 相似文献