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941.
Sigurd Höger Klaus Bonrad Silvia Rosselli Anne-Désirée Ramminger Thomas Wagner Beate Silier Simone Wiegand Wolfgang Häußler Günter Lieser Volker Scheumann 《Macromolecular Symposia》2002,177(1):185-191
Alkyl- and Oligostyrene substituents were attached to shape-persistent macrocycles based on a phenyl-ethynyl backbone. In good solvents for both the rigid core and the flexible corona no aggregation occurred. Whereas, addition of a solvent that selectively solubilizes the corona induced a solvophobic aggregation. For alkyl substituted rings the experimental data were described by a monomer-dimer equilibrium. In contrast, the oligostyrene substituted rings formed more expanded aggregates which were investigated by scattering and by imaging methods. The superstructures are consequently described as hollow supramolecular cylindrical brushes. 相似文献
942.
Andreas Guthausen Gisela Zinmer Simone Laukemper-Ostendor Peter Blümler Bernhard Blümich 《Chemie in Unserer Zeit》1998,32(2):73-82
Magnetic resonance imaging (MRI) is a powerful tool in medical diagnostics. But this technique of nuclear magnetic resonance (NMR) ist also receiving increasing attention in materials science because it is non-invasive and because of the abundance of different contrast parameters which reflect the molecular properties of the samples. For instance, distributions in microscopic molecular re-orientations as well as macroscopic coherent motion can be imaged by appropriate techniques. Applications of both aspects of MRI are reported by examples of images from elastomers, skin, and velocity profiles. In addition, a new method for investigations of surfacenear volume elements of arbitraril shaped samples is shown. 相似文献
943.
Conversion of hydrophobic polypropylene surfaces to hydrophilic, water wettable surfaces by adsorption of amphiphilic carbohydrates (“surfactant immobilization”) as well as by covalent bonding of sucrose residues via azid photolysis (“photochemical immobilization”) was investigated. Improvement of surface hydrophilicity was determined by contact angle measurements and application of special test inks for polyolefines. 相似文献
944.
The investigation of high-pressure autoignition of combustible mixtures is of importance in providing both practical information in the design of combustion systems and fundamental measurements to verify and develop chemical kinetic models. The autoignition characteristics of hydrogen-oxygen mixtures at low pressures have been explored extensively, whereas few measurements have been made at high pressures. The present measurements extend the range of pressures up to 4 MPa, where few measurements have yet been reported. Using a rapid compression machine equipped with a specially designed piston head, hydrogen autoignition pressure traces were measured at pressures above the second explosion limit (p=0.6–4 MPa, T=950–1050 K). The measured pressure records show a more gradual pressure increase during induction time in this regime than in the low-pressure regime, indicating that the energy release becomes significant at conditions over the second explosion limit. By comparing the measurements and a thermodynamic model which incorporates the heat transfer and energy release, a modified reaction rate constant for H2O2+H=HO2+H2, one of the most important reactions for hydrogen oxidation at high pressure, and the reaction with the largest uncertainty, is suggested in this work as k17=2.3 . 1013exp(−4000/T) cm3/mol-s. The modeled pressure history with the modified reaction rate agrees well with the measured values during the induction period over the range of conditions tested. © 1998 John Wiley & Sons, Inc. Int J Chem Kinet 30: 385–406, 1998 相似文献
945.
We have developed and validated a new adaptive method, particle tracking velocimetry and accelerometry (PTVA), to measure
velocity and acceleration from the post-processing of particle tracking (PT) data. This method is shown to be more accurate
than non-adaptive methods based on PT: errors are about six times smaller on velocity measurements and about four times smaller
on acceleration ones. We apply this method to a turbulent-like flow generated and controlled in the laboratory. Taking advantage
of the Eulerian repeatability of our multi-scale laminar flow, we are able to extract the acceleration field, a, and all terms of Navier–Stokes equation. To complete this we extract u·a and ∇·a fields. We finally compare the probability density function of the acceleration components of our turbulent-like flow with
one of the highly turbulent flows and show that they are similar. The quality of these PTVA results and their robustness (in
particular to local convection) are extremely encouraging. This method allows access to a deeper insight into the physic of
turbulent-like flows and its high accuracy may apply to a broader range of flows.
相似文献
Lionel RossiEmail: |
946.
Volker C. Kirsch Christina Orgler Simone Braig Irmela Jeremias David Auerbach Rolf Müller Angelika M. Vollmar Stephan A. Sieber 《Angewandte Chemie (International ed. in English)》2020,59(4):1595-1600
Novel targets are needed for treatment of devastating diseases such as cancer. For decades, natural products have guided innovative therapies by addressing diverse pathways. Inspired by the potent cytotoxic bioactivity of myxobacterial vioprolides A–D, we performed in‐depth studies on their mode of action. Based on its prominent potency against human acute lymphoblastic leukemia (ALL) cells, we conducted thermal proteome profiling (TPP) and deciphered the target proteins of the most active derivative vioprolide A (VioA) in Jurkat cells. Nucleolar protein 14 (NOP14), which is essential in ribosome biogenesis, was confirmed as a specific target of VioA by a suite of proteomic and biological follow‐up experiments. Given its activity against ALL cells compared to healthy lymphocytes, VioA exhibits unique therapeutic potential for anticancer therapy through a novel mode of action. 相似文献
947.
Selective Coordination of Gallium(III), Zinc(II), and Copper(II) by an Asymmetric Dinucleating Ligand: A Model for Metallophosphatases
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Dr. Simone Bosch Prof. Dr. Peter Comba Prof. Lawrence R. Gahan Dr. Christopher Noble Prof. Dr. Gerhard Schenk Prof. Dr. Hubert Wadepohl 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(50):18269-18279
Complexation studies of the dinucleating ligand H3L (H3L=2‐{[bis(pyridin‐2‐ylmethyl)amino]methyl}‐6‐{[bis(6‐pivaloylamidopyridin‐2‐ylmethyl)amino]methyl}‐4‐methylphenol), with metal‐binding sites A and B, which both provide four donors to a metal ion; a tertiary amine; two pyridines (substituted with amide hydrogen‐bond donors in site B), and a bridging phenolate, with ZnII, CuII, and GaIII are reported. The titration of H3L with the three metal ions in solution was monitored by NMR spectroscopy or EPR and UV/Vis/near‐IR spectroscopy, as well as by ESI‐MS to analyze the selectivity of the two metal‐ion sites A and B of this model ligand for metallophosphatases; the spectroscopic assignments are supported by X‐ray crystallography results. The first ZnII ion coordinates to site A with unsubstituted pyridine donors and, upon addition of a second equivalent of ZnII, this coordinates to the sterically less accessible site B. From a similar titration with GaIII, it emerges that only a mononuclear complex is obtained, with the GaIII center coordinated to site A. When one equivalent of GaIII is reacted with the mononuclear ZnII complex, ZnII is forced by GaIII to exchange the site; this results in a dinuclear complex with GaIII in site A and ZnII in site B. With CuII, two isomers are observed: one with and the other without a bridging phenolate; these differ significantly in their spectroscopic and magnetic properties. 相似文献
948.
949.
Luna Pollini Francesca Blasi Federica Ianni Luca Grispoldi Simone Moretti Alessandra Di Veroli Lina Cossignani Beniamino Terzo Cenci-Goga 《Molecules (Basel, Switzerland)》2022,27(6)
Currently, there is an increasing interest to valorise agri-food waste containing bioactive compounds with potential health benefits. In this paper, the recovery of functional molecules from apple pomace, the most abundant by-product of the apple processing industry, was carried out by ultrasound-assisted extraction (UAE) on fresh and freeze-dried samples. UAE extract, obtained by double extraction of freeze-dried apple pomace, was subjected to chromatographic and spectrophotometric characterization. It showed good levels of total phenol content, high antioxidant activity, and interesting antioxidant compounds (quercetin derivatives, chlorogenic acid, phloridzin). Subsequently, freeze-dried apple pomace, containing 40.19% of dietary fibre, was used as a fortifying agent for beef burgers (4% and 8%). The results concerning colour and sensory analysis of the fortified products were graded even better than the control (0%). The improved fibre and phenol content, together with the neutral flavour, represent the most interesting characteristics of fortified burgers. The results confirm that UAE was a successful technique for extracting phenol compounds and that the addition of apple pomace represents a valid approach to increase the health properties and palatability of beef burgers, including for consumers who do not like meat. 相似文献
950.
N. T. Do Valle C. A. De Simone M. A. Pereira M. O. F. Goulart 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(5):566-567
Interest in the title structure, C20H24O2, lies in the novel cis ring junction between the three‐ and seven‐membered rings. This stereochemical arrangement causes the methylene moiety and the cycloheptane ring to be twisted out of the plane of the aromatic ring. The cyclopropane ring is also twisted out of the plane of the aromatic system. The molecules are linked by an O—H?O hydrogen bond [O?O 2.741 (3) Å]. 相似文献