全文获取类型
收费全文 | 562篇 |
免费 | 44篇 |
国内免费 | 1篇 |
专业分类
化学 | 487篇 |
力学 | 5篇 |
数学 | 46篇 |
物理学 | 69篇 |
出版年
2024年 | 2篇 |
2023年 | 15篇 |
2022年 | 21篇 |
2021年 | 56篇 |
2020年 | 30篇 |
2019年 | 18篇 |
2018年 | 17篇 |
2017年 | 13篇 |
2016年 | 32篇 |
2015年 | 26篇 |
2014年 | 24篇 |
2013年 | 24篇 |
2012年 | 39篇 |
2011年 | 37篇 |
2010年 | 14篇 |
2009年 | 8篇 |
2008年 | 30篇 |
2007年 | 29篇 |
2006年 | 19篇 |
2005年 | 28篇 |
2004年 | 17篇 |
2003年 | 21篇 |
2002年 | 13篇 |
2001年 | 10篇 |
2000年 | 4篇 |
1999年 | 5篇 |
1998年 | 2篇 |
1997年 | 2篇 |
1996年 | 4篇 |
1993年 | 1篇 |
1992年 | 1篇 |
1991年 | 3篇 |
1990年 | 4篇 |
1989年 | 6篇 |
1988年 | 1篇 |
1987年 | 5篇 |
1986年 | 3篇 |
1985年 | 2篇 |
1984年 | 3篇 |
1983年 | 3篇 |
1982年 | 6篇 |
1981年 | 2篇 |
1980年 | 2篇 |
1979年 | 2篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1970年 | 1篇 |
排序方式: 共有607条查询结果,搜索用时 171 毫秒
101.
102.
103.
Dr. Mauro Carraro Dr. Giulia Fiorani Dr. Lorenzo Mognon Dr. Francesca Caneva Dr. Martino Gardan Dr. Chiara Maccato Dr. Marcella Bonchio 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(41):13195-13202
Anchoring terminal octenyl tails on molecular polyoxotungstates yield polymerizable organic–inorganic monomers with formula [{CH2?CH(CH2)6Si}xOySiWwOz]4? [x=2, w=11, y=1, z=39 ( 1 ); x=2, w=10, y=1, z=36 ( 2 ); and x=4, w=9, y=3, z=34 ( 3 )]. These molecular hybrids can use aqueous hydrogen peroxide to catalyze the selective oxidation of organic sulfides in CH3CN. Copolymerization of 1 – 3 with methyl methacrylate and ethylene glycol dimethacrylate leads to porous materials with a homogeneous distribution of the functional monomers, as indicated by converging evidence from FTIR spectroscopy and electronic microscopy. The catalytic polymers activate hydrogen peroxide for oxygen transfer, as demonstrated by the quantitative and selective oxidation of methyl p‐tolyl sulfide, which was screened as model substrate. The hybrid material containing monomer 2 was also tested in n‐octane to evaluate its potential for the oxidation and removal of dibenzothiophene, a well‐known gasoline contaminant. 相似文献
104.
Alessandro Massella Giulia D'Intino Mercedes Fernández Sandra Sivilia Luca Lorenzini Silvia Giatti Roberto C Melcangi Laura Calzà Luciana Giardino 《BMC neuroscience》2012,13(1):12
Background
Multiple sclerosis (MS) varies considerably in its incidence and progression in females and males. In spite of clinical evidence, relatively few studies have explored molecular mechanisms possibly involved in gender-related differences. The present study describes possible cellular- and molecular-involved markers which are differentially regulated in male and female rats and result in gender-dependent EAE evolution and progression. Attention was focused on markers of myelination (MBP and PDGFαR) and neuronal distress and/or damage (GABA synthesis enzymes, GAD65 and GAD67, NGF, BDNF and related receptors), in two CNS areas, i.e. spinal cord and cerebellum, which are respectively severely and mildly affected by inflammation and demyelination. Tissues were sampled during acute, relapse/remission and chronic phases and results were analysed by two-way ANOVA. 相似文献105.
Rehammar R Francescato Y Fernández-Domínguez AI Maier SA Kinaret JM Campbell EE 《Optics letters》2012,37(1):100-102
A square planar photonic crystal composed of carbon nanofibers was fabricated using e-beam lithography and chemical vapor deposition. The diffraction properties of the system were characterized experimentally and compared with theory and numerical simulations. The intensities of the (-1,0) and (-1,-1) diffraction beams were measured as functions of the angles of incidence for both s and p-polarization. The obtained radiation patterns can be explained using a simple ray interference model, but finite-difference time-domain (FDTD) calculations are necessary to reproduce the observed dependence of the scattered radiation intensity on incident laser polarization. We explain this in terms of the aspect ratio of the nanofibers and the excitation of surface plasmon polaritons at the substrate interface. 相似文献
106.
Optimization of a SPME/GC/MS Method for the Simultaneous Determination of Pharmaceuticals and Personal Care Products in Waters 总被引:2,自引:0,他引:2
A headspace solid phase microextraction (HS-SPME) method coupled with gas chromatography and MS detection (GC/MS) was optimized for the simultaneous determination of 21 target Pharmaceuticals and Personal Care Products (PPCPs) in water samples. The analytes included fragrances, UV-filters, antiseptics, estrogens, anti-inflammatory drugs, and pesticides. An on-fiber SPME derivatization, using silyl reagents, was performed for the analysis of more polar acidic compounds. An experimental design approach was applied to systematically investigate and optimize the operative parameters affecting the extraction recovery, namely: extraction temperature and time, derivatization time, desorption temperature and time. The optimum operating conditions were: extraction time of 125?min at a temperature of 40?°C; derivatization time of 30.5?min; desorption time of 2?min at a temperature of 300?°C. Under these conditions, good reproducibility was assessed as RDS% values ≤10% for underivatized PPCPs and ≤20% for derivatized compounds. The method detection limits (LOD) were between 0.7 and 9.0?ng?L?1, with the highest values in the range 2.5–9.0?ng?L?1 for the derivatized analytes. Method accuracy was evaluated on spiked tap water samples: recoveries varied from 85 to 103% and from 75 to 110% for non-derivatized and derivatized compounds, respectively. 相似文献
107.
108.
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. 相似文献
109.
Matteo Mori Giulia Cazzaniga Fiorella Meneghetti Stefania Villa Arianna Gelain 《Molecules (Basel, Switzerland)》2022,27(14)
SIRT5 is a member of the Sirtuin family, a class of deacetylating enzymes consisting of seven isoforms, involved in the regulation of several processes, including gene expression, metabolism, stress response, and aging. Considering that the anomalous activity of SIRT5 is linked to many pathological conditions, we present herein an overview of the most interesting modulators, with the aim of contributing to further development in this field. 相似文献
110.
Dr. Giulia Neri Dr. Giuliana Mion Dr. Andrea Pizzi Dr. Wanda Celentano Dr. Linda Chaabane Prof. Michele R. Chierotti Prof. Roberto Gobetto Dr. Min Li Prof. Piergiorgio Messa Dr. Floryan De Campo Prof. Francesco Cellesi Prof. Pierangelo Metrangolo Prof. Francesca Baldelli Bombelli 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(44):10057-10063
In the continuous search for multimodal systems with combined diagnostic and therapeutic functions, several efforts have been made to develop multifunctional drug delivery systems. In this work, through a covalent approach, a new class of fluorinated poly(lactic-co-glycolic acid) co-polymers (F-PLGA) were designed that contain an increasing number of magnetically equivalent fluorine atoms. In particular, two novel compounds, F3-PLGA and F9-PLGA, were synthesized and their chemical structure and thermal stability were analyzed by solution NMR, DSC, and TGA. The obtained F-PLGA compounds were proven to form in aqueous solution colloidal stable nanoparticles (NPs) displaying a strong 19F NMR signal. The fluorinated NPs also showed an enhanced ability to load hydrophobic drugs containing fluorine atoms compared to analogous pristine PLGA NPs. Preliminary in vitro studies showed high cell viability and the NP ability to intracellularly deliver and release a functioning drug. 相似文献