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991.
Electrochemical O-glycosylation of primary alcohols with O-protected thioglycosides was performed in the presence of a small amount of sodium trifluoromethansulfonate (12.5 mol % to glycosyl acceptor) as a supporting electrolyte. The reaction was successfully carried out in an undivided cell to give O-glycosides in good yields with a high electro-efficiency (ca. 1 F/mol) at 15 °C in acetonitrile. 相似文献
992.
Tadamasa Nemoto Daisuke Ando Kensuke Naka Yoshiki Chujo 《Journal of polymer science. Part A, Polymer chemistry》2006,44(16):4731-4735
To develop polycondensation methods for poly(α‐amino acid)s, we describe a first examination to use yttrium triflate as a Lewis acid for polycondensation of α‐amino acid esters. In the absence of Lewis acid, no polycondensation of 2‐methoxyphenyl glycinate ( 1b ) at room temperature proceeded. While the polycondensation of 1b was carried out with 5 mol % yttrium triflate, a condensation product of glycine was obtained in 16% yield. Although polycondensation of 4‐nitrophenyl L ‐leucinate ( 1c ) and 4‐nitrophenyl L ‐valinate ( 1d ) were also promoted with 5 mol % yttrium triflate, the condensation products of both α‐amino acid esters were obtained in only a few percent yield. When 1d was polymerized in the presence of 100 mol % yttrium triflate, high molecular weight poly(L ‐valine) was obtained in 91% yield. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 4731–4735, 2006 相似文献
993.
994.
Keiji Hayashi Daisuke Tanaka Harumi Araki Tomoki Maruyama Daisuke Matsumura Kazuho Toyoda Noriyuki Tsuji 《Applied Surface Science》2009,255(24):9581-9584
Ion-current difference measurement by light intensity modulation (ICD) is introduced as a convenient method to characterize a purified beam of momentum-controlled neutral free radicals produced by photo-deionization of a negative ion beam for the purpose of surface-reaction-selective device processing. The ICD setup developed in this study to estimate the number flux of the photo-deionized neutral particles exhibited the high precision, sensitivity, and spatial resolution. 相似文献
995.
采用含硅量较高(23wt%)的新型光致抗蚀剂实现了55nm的各种特性,获得了较高的耐腐蚀性能,并降低了线条边缘粗糙度。结果还表明,这种新型的光致抗蚀剂与浸没式光刻工艺具有良好的一致性。 相似文献
996.
Nicola Trivellin Matteo Meneghini Gaudenzio Meneghesso Enrico Zanoni Kenji Orita Masaaki Yuri Tsuyoshi Tanaka Daisuke Ueda 《Microelectronics Reliability》2009,49(9-11):1236-1239
The purpose of this work is an in depth reliability analysis of Blu-Ray InGaN laser diodes (LD) submitted to CW stress at different currents and temperatures. During reliability tests, LD devices exhibit a gradual threshold current increase, while slope efficiency is almost not affected by the ageing treatment. Furthermore we demonstrate that: (i) the degradation rate shows a linear correlation with stress current level; (ii) the Ith increase is correlated to the decrease in non-radiative lifetime (τnr); (iii) stress temperature acts as an accelerating factor for LD degradation; (iv) pure thermal storage does not significantly degrade LDs characteristics. 相似文献
997.
Ee Taek Hwang Khizar Sheikh Katherine L. Orchard Daisuke Hojo Valentin Radu Chong‐Yong Lee Emma Ainsworth Colin Lockwood Manuela A. Gross Tadafumi Adschiri Erwin Reisner Julea N. Butt Lars J. C. Jeuken 《Advanced functional materials》2015,25(15):2308-2315
In nature, charge recombination in light‐harvesting reaction centers is minimized by efficient charge separation. Here, it is aimed to mimic this by coupling dye‐sensitized TiO2 nanocrystals to a decaheme protein, MtrC from Shewanella oneidensis MR‐1, where the 10 hemes of MtrC form a ≈7‐nm‐long molecular wire between the TiO2 and the underlying electrode. The system is assembled by forming a densely packed MtrC film on an ultra‐flat gold electrode, followed by the adsorption of approximately 7 nm TiO2 nanocrystals that are modified with a phosphonated bipyridine Ru(II) dye (RuP). The step‐by‐step construction of the MtrC/TiO2 system is monitored with (photo)electrochemistry, quartz‐crystal microbalance with dissipation (QCM‐D), and atomic force microscopy (AFM). Photocurrents are dependent on the redox state of the MtrC, confirming that electrons are transferred from the TiO2 nanocrystals to the surface via the MtrC conduit. In other words, in these TiO2/MtrC hybrid photodiodes, MtrC traps the conduction‐band electrons from TiO2 before transferring them to the electrode, creating a photobioelectrochemical system in which a redox protein is used to mimic the efficient charge separation found in biological photosystems. 相似文献
998.
Hidenori Otsuka Taketomo Sanbai Daisuke Matsukuma Yusuke Ikenaga 《Colloid and polymer science》2014,292(2):291-300
We have newly synthesized amphiphilic block copolymers composed of hydrophilic poly(ethylene glycol) (PEG) and hydrophobic pyridine segments (PEG-b-Py). Chain transfer agent-terminated PEG was subsequently chain-extended with 3-(4-pyridyl)-propyl acrylate to obtain PEG-b-Py by reversible additional-fragmentation chain transfer polymerization. Particularly, the effect of varying molecular weight (Mn) of PEG (Mn?=?2,000 and 5,000) and Py in the block copolymers was investigated in terms of critical micelle concentration, pyrene solubilization, micelle size distribution, and association number per micelle. Based on the amphiphilic balance, PEG-b-Pys formed core-shell type polymer micelle. The association number of PEG2k-b-Py was higher than that of PEG5k-b-Py, suggesting the degree of phase separation strongly depended on PEG Mn. Furthermore, the adsorption of PEG-b-Py copolymer onto silica nanoparticles as dispersant was studied to estimate the effect of PEG Mn in the copolymers and their solubility in the medium on the adsorption. Adsorbed density of PEG2k-b-Py copolymer onto silica nanoparticle was higher than that of PEG5k-b-Py, which was significantly correlated with the degree of phase separation. Furthermore, the adsorbed amount of copolymer increased with the increase in ionic strength due to the reduced solubility of PEG in the buffer solution. The resultant dispersion stability was highly correlated with the graft density of copolymer onto silica surface. However, the stability of PEG2k-b-Py coated particles was lower than that with PEG5k-b-Py, this is attributed to the relatively thin layer of PEG at the silica surface, which cannot provide the system with sufficient steric stabilization as the salt concentration increases. These fundamental investigations for the surface modification of the nanoparticle provide the insight into the highly stable colloidal dispersion, particularly in the physiological condition with high ionic strength. 相似文献
999.
Masanobu Mori Toshinobu Suzuki Tsuyoshi Sugita Daisuke Nagai Kazuo Hirayama Makoto Onozato Hideyuki Itabashi 《Analytica chimica acta》2014
This study aimed to evaluate the heavy metal adsorptivity of calcium-alginate-modified diethylenetriamine-silica gel (CaAD) and incorporate this biosorbent into a flow analytical system for heavy metal ions using flame atomic absorption spectrometry (FAAS). The biosorbent was synthesized by electrostatically coating calcium alginate onto diethylenetriamine (dien)-silica gel. Copper ion adsorption tests by a batch method showed that CaAD exhibited a higher adsorption rate compared with other biosorbents despite its low maximum adsorption capacity. Next, CaAD was packed into a 1 mL microcolumn, which was connected to a flow analytical system equipped with an FAAS instrument. The flow system quantitatively adsorbed heavy metals and enriched their concentrations. This quantitative adsorption was achieved for pH 3–4 solutions containing 1.0 × 10−6 M of heavy metal ions at a flow rate of 5.0 mL min−1. Furthermore, the metal ions were successfully desorbed from CaAD at low nitric acid concentrations (0.05–0.15 M) than from the polyaminecarboxylic acid chelating resin (Chelex 100). Therefore, CaAD may be considered as a biosorbent that quickly adsorbs and easily desorbs analyte metal ions. In addition, the flow system enhanced the concentrations of heavy metals such as Cu2+, Zn2+, and Pb2+ by 50-fold. This new enrichment system successfully performed the separation and determination of Cu2+ (5.0 × 10−8 M) and Zn2+ (5.7 × 10−8 M) in a river water sample and Pb2+ (3.8 × 10−9 M) in a ground water sample. 相似文献
1000.
Switching of Single‐Molecule Magnetic Properties of TbIII–Porphyrin Double‐Decker Complexes and Observation of Their Supramolecular Structures on a Carbon Surface
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Tomoko Inose Dr. Daisuke Tanaka Prof. Dr. Hirofumi Tanaka Dr. Oleksandr Ivasenko Prof. Dr. Toshi Nagata Yusuke Ohta Prof. Dr. Steven De Feyter Prof. Dr. Naoto Ishikawa Prof. Dr. Takuji Ogawa 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(36):11362-11369
Double‐decker complexes based on single‐molecule magnets (SMMs) are a class of highly promising molecules for applications in molecular spintronics, wherein control of both the ligand oxidative states and the 2D supramolecular structure on carbon materials is of great importance. This study focuses on the synthesis and study of 2,3,7,8,12,13,17,18‐octaethylporphyrin (OEP)–TbIII double‐decker complexes with different electronic structures comprising protonated, anionic, and radical forms. Magnetic susceptibility measurements revealed that only the anionic and radical forms of the OEP–TbIII double‐decker complexes exhibited SMM properties. The barrier heights for magnetic moment reversal were estimated to be 207 and 215 cm?1 for the anionic and radical forms, respectively. Scanning tunneling microscopy (STM) investigations revealed that these OEP–TbIII complexes form well‐ordered monolayers upon simple dropcasting from dilute dichloromethane solutions. All three complexes form an isomorphic pseudo‐hexagonal 2D pattern, regardless of the differences in the electronic structures of their porphyrin–Tb cores. This finding is of interest for SMM technology as ultrathin films of these materials undergoing chemical transformations will not require any detrimental reorganization. Finally, we demonstrate self‐assembly of the protonated 5,15‐bisdodecylporphyrin (BDP)–TbIII double‐decker complex as an example of successful supramolecular design to achieve controlled alignment of SMM‐active sites. 相似文献