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981.
Reaction of [(((Ad)ArO)(3)tacn)U(III)] (1) or [((Me(3)Si)(2)N)(3)U(III)] (3) with tetramethylimidazol-2-ylidene (Me(4)IMC:) yields novel N-heterocyclic carbene complexes [(((Ad)ArO)(3)tacn)U(III)(Me(4)IMC:)] (2) and [((Me(3)Si)(2)N)(3)U(III)(Me(4)IMC:)] (4). Uranium complexes 2 and 4 represent the first examples of compounds with an N-heterocyclic carbene ligand coordinated to a low-valent uranium center. The paramagnetic complexes 1, 2, and 4 were characterized by (1)H NMR, UV-vis-NIR, and EPR spectroscopy as well as SQUID magnetization measurements and X-ray diffraction analyses. DFT studies indicate a significant degree of pi-bonding in the U(III)-carbene entity. 相似文献
982.
Johanna Schfermann Georg Kliewer Jan Lsch Hanna Bednarz Marco Giamp Karsten Niehaus 《Journal of mass spectrometry : JMS》2020,55(3)
Automated matrix deposition for matrix‐assisted laser desorption/ionization (MALDI) mass spectrometry imaging (MSI) is crucial for producing reproducible analyte ion signals. Here we report an innovative method employing an automated immersion apparatus, which enables a robust matrix deposition within 5 minutes and with scalable throughput by using MAPS matrix and non‐polar solvents. MSI results received from mouse heart and rat brain tissues were qualitatively similar to those from nozzle sprayed samples with respect to peak number and quality of the ion images. Overall, the immersion‐method enables a fast and careful matrix deposition and has the future potential for implementation in clinical tissue diagnostics. 相似文献
983.
Benjamin Schmidt Sebastian Ponath Johannes Hannemann Patrick Voßnacker Dr. Karsten Sonnenberg Prof. Dr. Mathias Christmann Prof. Dr. Sebastian Riedel 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(66):15183-15189
The use of neat BrCl in organic and inorganic chemistry is limited due to its gaseous aggregate state and especially its decomposition into Cl2 and Br2. The stabilization of BrCl in form of reactive ionic liquids via a novel in situ synthesis route shifts this equilibrium drastically to the BrCl side, which leads to safer and easier-to-handle interhalogenation reagents. Furthermore, the crystalline derivatives of the hitherto unknown [Cl(BrCl)2]− and [Cl(BrCl)4]− anions were synthesized and characterized by single-crystal X-ray diffraction (XRD), Raman and IR spectroscopy, as well as quantum chemical calculations. 相似文献
984.
985.
Wei Wei Steffen Berger Christina Hauser Karsten Meyer Min Yang Patrik Schmuki 《Electrochemistry communications》2010,12(9):1184-1186
Over the past decade, the electrochemical formation of self-organized nanotube layers in dilute fluoride containing electrolytes has been studied intensively. In the present work, we show that by anodization of Ti in similar electrolytes but containing only very low water contents, the formation of ordered TiO2 nanoporous structures can be observed. I.e., the water content in the electrolyte is the critical factor that decides whether self-ordered oxide tubes or pores are formed. This supports the concept that tube formation originates from ordered porous oxide by a “pore-wall-splitting” mechanism. 相似文献
986.
987.
988.
Karsten Nödler Tobias Licha Kai Bester Martin Sauter 《Journal of chromatography. A》2010,1217(42):6511-6521
A multi-residue analytical method based on high-performance liquid chromatographic separation, electrospray ionization with tandem mass spectrometric detection (HPLC/MS–MS) was developed for the simultaneous analysis of 46 basic, neutral and acidic compounds covering a wide range of polarity (log KOW < 0–5.9). The compound list included selected iodinated contrast media, analgesics, anti-inflammatories, stimulants, beta-blockers, antibiotics, lipid regulators, anti-histamines, psychiatric drugs, herbicides, corrosion inhibitors and the gastric acid regulator pantoprazole. The main feature of the presented method was a simultaneous solid phase extraction (SPE) of all analytes followed by simultaneous separation and detection by HPLC/MS–MS with electrospray ionization in both positive and negative polarization within the same chromatogram. Optimization of electrospray drying gas temperature resulted in using a temperature gradient on the ion source. Six different polymeric sorbents for SPE were compared with respect to recoveries, taking into account the specific surface of each sorbent. Method quantitation limits (MQL) in surface and seawater ranged from 1.2 to 28 ng/L, in wastewater from 5.0 to 160 ng/L, respectively. In order to demonstrate the applicability of the method, river water, treated wastewater and seawater were analyzed. 相似文献
989.
Molecularly imprinted polymers (MIPs) are tailor-made synthetic materials possessing specific cavities designed for a target
molecule. Since they recognise their target analyte with affinities and selectivities comparable to those of antibody–antigen,
enzyme–substrate and ligand–receptor interactions, they are often referred to as synthetic receptors or plastic antibodies.
In this review, we describe the great potential and recent developments of MIPs in affinity separations, with emphasis on
their application to the solid-phase extraction (SPE) of analytes from complex matrices. Research efforts made in this field
to obtain water-compatible polymers for their applicability in aqueous environments are described. We particularly discuss
problems encountered in the use of MIPs in SPE and the attempts carried out to improve their efficiency. 相似文献
990.
Aaron Bostwick Jessica McChesney Taisuke Ohta Eli Rotenberg Thomas Seyller Karsten Horn 《Progress in Surface Science》2009,84(11-12):380-413
Graphene, the single layer of hexagonally coordinated carbon, is a two-dimensional material with many unusual properties; its physical realization a few years ago has caused a storm of activities in the solid state physics and materials science communities. The intriguing “massless Dirac Fermion” character of its charge carriers renders graphene a unique study object in condensed matter physics, and we discuss how surface-related techniques such as photoemission, STM and LEED play a prominent role in these investigations. We report on experimental studies of the growth and electronic structure of epitaxial single and few layer graphene on silicon carbide. The unusual band structure of single layer graphene and its evolution as layers are added towards bulk graphite is studied. In the special case of the bilayer, the opening of a gap by inducing an asymmetry through the influence of doping is examined. Finally, the influence of many body processes on the spectral function is discussed on the basis of high resolution photoemission data. The discussion of these aspects gives a comprehensive overview of the electronic structure of graphene as examined by experiment. 相似文献