全文获取类型
收费全文 | 2802篇 |
免费 | 379篇 |
国内免费 | 81篇 |
专业分类
化学 | 2213篇 |
晶体学 | 5篇 |
力学 | 47篇 |
综合类 | 4篇 |
数学 | 13篇 |
物理学 | 609篇 |
综合类 | 371篇 |
出版年
2024年 | 9篇 |
2023年 | 52篇 |
2022年 | 79篇 |
2021年 | 87篇 |
2020年 | 96篇 |
2019年 | 117篇 |
2018年 | 70篇 |
2017年 | 118篇 |
2016年 | 157篇 |
2015年 | 185篇 |
2014年 | 198篇 |
2013年 | 250篇 |
2012年 | 216篇 |
2011年 | 192篇 |
2010年 | 173篇 |
2009年 | 146篇 |
2008年 | 159篇 |
2007年 | 149篇 |
2006年 | 149篇 |
2005年 | 112篇 |
2004年 | 113篇 |
2003年 | 83篇 |
2002年 | 49篇 |
2001年 | 34篇 |
2000年 | 31篇 |
1999年 | 39篇 |
1998年 | 35篇 |
1997年 | 26篇 |
1996年 | 29篇 |
1995年 | 28篇 |
1994年 | 22篇 |
1993年 | 15篇 |
1992年 | 16篇 |
1991年 | 4篇 |
1990年 | 10篇 |
1989年 | 5篇 |
1988年 | 3篇 |
1987年 | 3篇 |
1986年 | 1篇 |
1982年 | 1篇 |
1970年 | 1篇 |
排序方式: 共有3262条查询结果,搜索用时 15 毫秒
81.
Chiara Capolungo Dr. Damiano Genovese Prof. Marco Montalti Prof. Enrico Rampazzo Prof. Nelsi Zaccheroni Prof. Luca Prodi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(70):17529-17541
The growing numbers related to plastic pollution are impressive, with ca. 70 % of produced plastic (>350 tonnes/year) being indiscriminately wasted in the environment. The most dangerous forms of plastic pollution for biota and human health are micro- and nano-plastics (MNPs), which are ubiquitous and more bioavailable. Their elimination is extremely difficult, but the first challenge is their detection since existing protocols are unsatisfactory for microplastics and mostly absent for nanoplastics. After a discussion of the state of the art for MNPs detection, we specifically revise the techniques based on photoluminescence that represent very promising solutions for this problem. In this context, Nile Red staining is the most used strategy and we show here its pros and limitations, but we also discuss other more recent approaches, such as the use of fluorogenic probes based on perylene-bisimide and on fluorogenic hyaluronan nanogels, with the added values of biocompatibility and water solubility. 相似文献
82.
Xiaoya Wang Bingbing Liu Jie Li Yunyun Zhai Haiqing Liu Lei Li Herui Wen 《Electroanalysis》2021,33(6):1484-1490
2D metal-organic framework (MOF) has potential applications in electrocatalysis owing to fast mass transfer, charge transfer and large specific surface area. Here, we had prepared three conductive 2D MOF based on Ni, NiCo and Co in a simple and rapid way. The 2D nanostructure of MOF was confirmed by SEM and TEM. The chemical composition was studied by XRD, Raman and XPS spectrum. The electrochemical oxidation and detection was investigated through cyclic voltammetry and current-time method. Their sensing performance for urea was determined by varying oxidation potentials and metal sites. The non-enzymatic Ni-, NiCo- and Co-MOF sensors had good catalytic activity for urea. Compared with NiCo- and Co-MOF, Ni-MOF had a wider linear range (0.5–832.5 μM), high sensitivity (1960 μA mM−1 cm−2), low detection limit (0.471 μM), and fast response time. The sensors had well repeatability, reproducibility, and selectivity to specific interfering species. Furthermore, Ni- and NiCo-MOF modified electrode was also applied to detection of milk samples. The results showed that the recovery was satisfactory, which further confirmed the effectiveness of non-enzyme sensor. In general, the highly-sensitive 2D Ni- and NiCo-MOF modified electrode has great potential as nonenzymatic urea sensors for real samples detection in hydrogen energy, clinical diagnostics, and environmental protection, et al. 相似文献
83.
The determination of two imidazoline derivatives [oxymetazoline HCl (OXY) and xylometazoline HCl (XYLO)] was described using different potentiometric platforms. The first electrode type was constructed using tetraphenyl borate (TPB) as anionic exchanger with β-cyclodextrins (β-CD) as ionophore forming oxymetazoline-tetraphenyl borate (OXY-TPB) and xylometazoline-tetraphenyl borate (XYLO-TPB), respectively. The second electrode type was prepared by modification of the first type by conjugation with magnetic iron oxide nanoparticles (MNP) forming (OXY-MNP) and (XYLO-MNP). The synthesized electrodes were fully characterized. The effect of magnetic nano-sized particles as a highly dispersible material with β-CDs on the electrode characteristics was investigated and compared against the classical electrodes. The response time, working pH range and selectivity coefficients were studied. The functionalized nano-electrodes (OXY-MNP and (XYLO-MNP) were found to be more sensitive than the classical electrodes with linearity ranges (1×10−6–1×10−2 M). The functionalized nano-electrodes were successfully applied for the in-line analysis of OXY and XYLO in pharmaceutical dosage forms and spiked rabbit aqueous humor samples with no prior extraction of treatment. This suggests the future use of these electrodes in clinical studies of both drugs of interest. 相似文献
84.
Nicola Y. Edwards David M. Schnable Ioana R. Gearba-Dolocan Jenna L. Strubhar 《Molecules (Basel, Switzerland)》2021,26(1)
Lanthanide complexes have been developed and are reported herein. These complexes were derived from a terpyridine-functionalized calix[4]arene ligand, chelated with Tb3+ and Eu3+. Synthesis of these complexes was achieved in two steps from a calix[4]arene derivative: (1) amide coupling of a calix[4]arene bearing carboxylic acid functionalities and (2) metallation with a lanthanide triflate salt. The ligand and its complexes were characterized by NMR (1H and 13C), fluorescence and UV-vis spectroscopy as well as MS. The photophysical properties of these complexes were studied; high molar absorptivity values, modest quantum yields and luminescence lifetimes on the ms timescale were obtained. Anion binding results in a change in the photophysical properties of the complexes. The anion sensing ability of the Tb(III) complex was evaluated via visual detection, UV-vis and fluorescence studies. The sensor was found to be responsive towards a variety of anions, and large binding constants were obtained for the coordination of anions to the sensor. 相似文献
85.
John Bentley Dr. Salil Desai Dr. Bishnu Prasad Bastakoti 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(36):9241-9252
Tungsten oxide (WO3) has received ever more attention and has been highly researched over the last decade due to its being a low-cost transition metal semiconductor with tunable, yet widely stable, band gaps. This minireview briefly highlights the challenges in the design and synthesis of porous WO3 including methods, precursors, solvent effects, crystal phases, and surface activities of the porous WO3 base material. These topics are explored while also drawing a connection of how the morphology and crystal phase affect the band gap. The shifts in band gap not only impact the optical properties of tungsten but also allow tuning to operate on different energy levels, which makes WO3 highly desirable in many applications such as supercapacitors, batteries, solar cells, catalysts, sensors, smart windows, and bioapplications. 相似文献
86.
Excessive uric acid levels in the human body (hyperuricemia) are the main causes of kidney stones and diabetes. In this study, a layer-by-layer arrangement of polymers and nanocomposites is used as a new electrode sensing material for rapid and direct electrochemical determination of uric acid (UA). The electrode surface architecture was constructed by the incorporation of poly (amidoamine) dendrimer with 0.5 generation (poly (amidoamine) [PAMAM] [D-G0.5]) of multiwalled carbon nanotube-silver nanoparticles (MWCNT-AgNP) and a poly (neutral-red) (poly [NR]) polymer. The PAMAM (D-G0.5)/MWCNT-AgNP/poly (NR)-coated electrode has a good electrocatalytic activity for the determination of UA using cyclic voltammetry and showed remarkable enhancement in current response at a low-oxidation potential (0.3 V). Under optimal conditions, the developed electrochemical sensor showed an excellent and wide linear range for the determination of UA (i.e. 0.016 μM–2500 μM), and the limit of detection was found to be 0.005 μM. The modified sensor system demonstrated excellent sensitivity and selectivity toward the detection of UA in the presence of interfering substances, which are commonly found in urine and human fluid samples. Furthermore, the developed sensor has represented both reproducibility and excellent stability for the UA determination in real samples (human urine). 相似文献
87.
Dounia Elfadil Abderrahman Lamaoui Flavio Della Pelle Aziz Amine Dario Compagnone 《Molecules (Basel, Switzerland)》2021,26(15)
Detection of relevant contaminants using screening approaches is a key issue to ensure food safety and respect for the regulatory limits established. Electrochemical sensors present several advantages such as rapidity; ease of use; possibility of on-site analysis and low cost. The lack of selectivity for electrochemical sensors working in complex samples as food may be overcome by coupling them with molecularly imprinted polymers (MIPs). MIPs are synthetic materials that mimic biological receptors and are produced by the polymerization of functional monomers in presence of a target analyte. This paper critically reviews and discusses the recent progress in MIP-based electrochemical sensors for food safety. A brief introduction on MIPs and electrochemical sensors is given; followed by a discussion of the recent achievements for various MIPs-based electrochemical sensors for food contaminants analysis. Both electropolymerization and chemical synthesis of MIP-based electrochemical sensing are discussed as well as the relevant applications of MIPs used in sample preparation and then coupled to electrochemical analysis. Future perspectives and challenges have been eventually given. 相似文献
88.
Stela Georgieva Artem Bezfamilnyi Anton Georgiev Marian Varbanov 《Molecules (Basel, Switzerland)》2021,26(19)
Herein, the spectral and electrochemical characterizations of three different substituted N-phthalimide azo-azomethine (NAA) dyes (L) containing an o-hydroxy group and their NAA-M(II) chelates [M(II): Cu, Ni, Co, Pb] were reported by using UV–Vis and fluorescence spectroscopy and potentiometric and voltamperometric techniques. The pK value of the dyes as well as the stoichiometry and stability of the NAA-metal chelates were studied, and the stoichiometry was found to be mostly 1:2 (ML2) with high complex stability constant values. The sensor activity of N-phthalimide azo-azomethine derivatives toward pH and metal ions has been also investigated and tested for indicator application in acid–base analysis and detection of Cu(II) ions in real samples of surface river water using voltamperometric detection. The results showed that one of the ligands possesses the highest electrochemical response upon binding to copper ions and could be successfully used in the analysis of copper in water at a concentration range of the analyte from 3.7 × 10−7 to 5.0 × 10−6 mol L−1, with analytical characteristics of the method being Sr = 1.5%, LOD = 3.58 µg L−1 and LOQ =11.9 µg L−1 相似文献
89.
Juliane R. Sempionatto Aida Martin Laura García‐Carmona Abbas Barfidokht Jonas F. Kurniawan Jose R. Moreto Guangda Tang Andrew Shin Xiaofeng Liu Alberto Escarpa Joseph Wang 《Electroanalysis》2019,31(2):239-245
A flexible skin‐mounted microfluidic potentiometric device for simultaneous electrochemical monitoring of sodium and potassium in sweat is presented. The wearable device allows efficient natural sweat pumping to the potentiometric detection chamber, containing solid‐contact ion‐selective Na+ and K+ electrodes, during exercise activity. The fabricated microchip electrolyte‐sensing device displays good analytical performance and addresses sweat mixing and carry‐over issues of early epidermal potentiometric sensors. Such soft skin‐worn microchip platform integrates potentiometric measurement, microfluidic technologies with flexible electronics for real‐time wireless data transmission to mobile devices. The new fully integrated microfluidic electrolyte‐detection device paves the way for practical fitness and health monitoring applications. 相似文献
90.
Tolga Kaya Gengchen Liu Jenny Ho Kumar Yelamarthi Kevin Miller Jeffrey Edwards Alicja Stannard 《Electroanalysis》2019,31(3):411-421
Sweat‐related physiology research has been well established over the years. However, it has only been around ten years that sweat‐based sensing devices started to be explored. With the recent advancements in wearable activity and physiology monitoring devices, sweat was investigated for its contents similar to blood and corresponding wearable devices were studied intensively. This article provides a thorough review on sweating mechanisms, sweat sensing devices, and electronic technologies for sweat sensor implementations. Potential future directions and recommendations based on current research trends were provided in each section. This review aims to offer a unique perspective from both physiology and engineering point‐of‐view to draw a complete landscape of the sweat sensing research. 相似文献