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991.
Angelika Odachowska Magdalena Godlewska Monika Turkowicz Patrycja Mateuszczyk Magdalena Iwanowicz 《液相色谱法及相关技术杂志》2017,40(3):126-132
A new sensitive method for the determination of lipoic acid (LA) in selected food items based on its reaction with Mukaiyama reagent (2-chloro-1-methylpyridinium iodide, CMPI) was developed. It was stated that CMPI reacts with reduced form of lipoic acid (dihydrolipoic acid, DHLA) and the stable product is produced. The spectrum of the labeled form of DHLA exhibits new band at 312?nm. Based on its spectral characteristics new spectrophotometric and UV–high-performance liquid chromatography (HPLC) methods of LA determination were elaborated. Both methods allowed determination of the analyte in the concentration range of 5?×?10?6–1?×?10?4?mol?L?1 with limit of detection 0.39?×?10?6 and 0.77?×?10?6?mol?L?1 for spectrophotometric and HPLC method, respectively. The practical usability of newly developed methods was checked by determination of lipoic acid contents in its pharmaceutical preparate Revitanerw. The proposed method was precise and accurate. The relative error of determination did not exceed ±0.067%. As chromatographic method allowed the determination of analyte in the presence of complex matrix, it was applied for assay of free fraction of α-lipoic acid in selected food items. A procedure of LA isolation from biological matrix was developed. The extraction with dichloromethane allowed quantitative recovery at 102.94?±?4.20%. The green barley appeared to be the richest source of LA. 相似文献
992.
A new single‐layer kinetic block model of crystal growth is proposed, which takes into account preference for bonds between blocks of the same type over mixed‐type bonds. The obtained parameters describing stable growth conditions were compared with other theoretical models (such as thermodynamic Jackson model and the earlier proposed kinetic model based on zeroth order approximation) which assume that new growth units are attached in a completely random way. Additionally, the results were compared with Monte Carlo simulations. The proposed model produced results which matched the simulation results much better than the other theoretical models. The new model can be used for studying crystal growth both from solution and from vapour. Calculations based on this model show that the number of created mixed‐type bonds depends on the temperature and is lower from its estimation obtained with the use of the zeroth order (Bragg‐Williams) approximation. 相似文献
993.
Łukasz Orzeł Justyna Polaczek Magdalena Procner 《Journal of Coordination Chemistry》2015,68(17-18):2971-2989
Cobalt and manganese porphyrins are known for their ability to activate small molecules. This is particularly important in the case of nitric oxide, whose role and mechanism of action in the redox biological systems have not yet been fully recognized. The goal of this article is to draw attention to some of the current trends of research in this area. The interactions involving NO itself and the primary products of its oxidation (nitrite) and reduction (nitroxyl) have been distinguished and separately discussed. The diversity of undertaken issues sheds light on both the expected behavior in biologically relevant systems as well as potential practical applications. 相似文献
994.
Dr. Joe Briscoe Adam Marinovic Dr. Marta Sevilla Dr. Steve Dunn Dr. Magdalena Titirici 《Angewandte Chemie (International ed. in English)》2015,54(15):4463-4468
New hybrid materials consisting of ZnO nanorods sensitized with three different biomass‐derived carbon quantum dots (CQDs) were synthesized, characterized, and used for the first time to build solid‐state nanostructured solar cells. The performance of the devices was dependent on the functional groups found on the CQDs. The highest efficiency was obtained using a layer‐by‐layer coating of two different types of CQDs. 相似文献
995.
A Potent,Selective and Cell‐Active Allosteric Inhibitor of Protein Arginine Methyltransferase 3 (PRMT3)
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Dr. H. Ümit Kaniskan Dr. Magdalena M. Szewczyk Dr. Zhengtian Yu Dr. Mohammad S. Eram Dr. Xiaobao Yang Keith Schmidt Dr. Xiao Luo Miao Dai Dr. Feng He Irene Zang Dr. Ying Lin Dr. Steven Kennedy Dr. Fengling Li Elena Dobrovetsky Aiping Dong Dr. David Smil Dr. Sun‐Joon Min Dr. Melissa Landon Dr. Jennifer Lin‐Jones Dr. Xi‐Ping Huang Prof. Dr. Bryan L. Roth Prof. Dr. Matthieu Schapira Dr. Peter Atadja Dr. Dalia Barsyte‐Lovejoy Prof. Dr. Cheryl H. Arrowsmith Dr. Peter J. Brown Dr. Kehao Zhao Prof. Dr. Jian Jin Prof. Dr. Masoud Vedadi 《Angewandte Chemie (International ed. in English)》2015,54(17):5166-5170
PRMT3 catalyzes the asymmetric dimethylation of arginine residues of various proteins. It is essential for maturation of ribosomes, may have a role in lipogenesis, and is implicated in several diseases. A potent, selective, and cell‐active PRMT3 inhibitor would be a valuable tool for further investigating PRMT3 biology. Here we report the discovery of the first PRMT3 chemical probe, SGC707, by structure‐based optimization of the allosteric PRMT3 inhibitors we reported previously, and thorough characterization of this probe in biochemical, biophysical, and cellular assays. SGC707 is a potent PRMT3 inhibitor (IC50=31±2 nM , KD=53±2 nM ) with outstanding selectivity (selective against 31 other methyltransferases and more than 250 non‐epigenetic targets). The mechanism of action studies and crystal structure of the PRMT3‐SGC707 complex confirm the allosteric inhibition mode. Importantly, SGC707 engages PRMT3 and potently inhibits its methyltransferase activity in cells. It is also bioavailable and suitable for animal studies. This well‐characterized chemical probe is an excellent tool to further study the role of PRMT3 in health and disease. 相似文献
996.
A Functional Role for Aβ in Metal Homeostasis? N‐Truncation and High‐Affinity Copper Binding
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Mariusz Mital Nina E. Wezynfeld Tomasz Frączyk Magdalena Z. Wiloch Urszula E. Wawrzyniak Arkadiusz Bonna Carolin Tumpach Kevin J. Barnham Cathryn L. Haigh Wojciech Bal Simon C. Drew 《Angewandte Chemie (International ed. in English)》2015,54(36):10460-10464
Accumulation of the β‐amyloid (Aβ) peptide in extracellular senile plaques rich in copper and zinc is a defining pathological feature of Alzheimer′s disease (AD). The Aβ1–x (x=16/28/40/42) peptides have been the primary focus of CuII binding studies for more than 15 years; however, the N‐truncated Aβ4–42 peptide is a major Aβ isoform detected in both healthy and diseased brains, and it contains a novel N‐terminal FRH sequence. Proteins with His at the third position are known to bind CuII avidly, with conditional log K values at pH 7.4 in the range of 11.0–14.6, which is much higher than that determined for Aβ1–x peptides. By using Aβ4–16 as a model, it was demonstrated that its FRH sequence stoichiometrically binds CuII with a conditional Kd value of 3×10?14 M at pH 7.4, and that both Aβ4–16 and Aβ4–42 possess negligible redox activity. Combined with the predominance of Aβ4–42 in the brain, our results suggest a physiological role for this isoform in metal homeostasis within the central nervous system. 相似文献
997.
Comparison of mouse plasma and brain tissue homogenate sample pretreatment methods prior to high‐performance liquid chromatography for a new 1,2,4‐triazole derivative with anticonvulsant activity
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Jolanta Flieger Anna Kowalska Magdalena Pizoń Tomasz Plech Jarogniew Łuszczki 《Journal of separation science》2015,38(12):2149-2157
The focus of the study was to develop a bio‐analytical assay for a 1,2,4‐triazole derivative from plasma and brain tissue homogenate samples. The goal was to compare analytical techniques that facilitate high accuracy with simplified sample processing. In this study, commonly used standard protein precipitation and solid‐phase extraction methods utilizing C18 and cartridges of Hybrid technology were compared in terms of their ability for sample pretreatment and removal of biological matrices before high‐performance liquid chromatography quantification. Fast classical reversed‐phase chromatography on a C18 column paired with selective sample preparation using Hybrid solid‐phase extraction technology resulted in the most precise bio‐analytical determination of the hydrophobic 1,2,4‐triazole derivative in both biological samples studied. The obtained recovery values were above 95% with the coefficient of variation lower than 5%. 相似文献
998.
Magdalena Maecka Agnieszka Rybarczyk‐Pirek Tomasz A. Olszak Katarzyna Malinowska Justyn Ochocki 《Acta Crystallographica. Section C, Structural Chemistry》2001,57(5):513-514
The X‐ray structure analysis of [Ni(C5H8N2)4(H2O)2]Cl2 was undertaken to elucidate the geometry around the Ni2+ ion. The molecule lies on a twofold axis which runs through the O—Ni—O atoms. The geometry around the Ni2+ ion is best described as slightly distorted tetragonal bipyramidal. 相似文献
999.
Getting access to the effective diffusion coefficient is a key point to provide realistic predictions of migration of radionuclides from radioactive waste repository in deep argillaceous geological formations. In the present work, the effective diffusion coefficient was computed inside an argillite micro-fracture as a function of its saturation level. The micrometric fracture geometry was extracted from the X-ray \(\mu \)-tomography image (\(0.7\,\upmu \mathrm{m}\) voxel resolution) of an Opalinus clay sample. It was collected in the host rock excavated damaged zone surrounding a borehole in the Mont Terri laboratory. The computations were performed using two two-relaxation-time lattice Boltzmann models. The first one, a phase separation model, was used to extract the connected liquid phase inside the fracture for given saturations. The second, a diffusion model, was used to compute non-reactive tracer diffusion in the connected liquid phase of the fracture and to calculate the effective diffusion coefficient for the associated saturations. The dependence of the effective diffusion coefficient on saturation was found to be quasi-linear and to qualitatively match the Maxwell expression for saturations lower than 0.8. 相似文献
1000.
Łukasz Piskorski Magdalena Marciniak Jarosław Walczak 《Optical and Quantum Electronics》2017,49(5):199
We present the simulation results of threshold operation of mid-infrared GaSb-based vertical-cavity surface-emitting lasers (VCSELs) obtained with the use of comprehensive fully self-consistent optical-electrical-thermal-recombination numerical model. The results show that by a proper design of VCSEL structure and composition of the active region it is theoretically possible to achieve room-temperature (RT) threshold operation for wavelength of 2.8 μm which is about 0.2 μm longer than those reported so far in the literature for III-V VCSELs with type-I quantum wells. Calculated values of the RT threshold current were equal to 2.5 and 4.0 mA for tunnel-junction diameters of 2 and 4 μm, respectively. 相似文献