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991.
Solution Layer Deposition: A Technique for the Growth of Ultra‐Pure Manganese Oxides on Silica at Room Temperature 下载免费PDF全文
Dr. Jérémy Cure Dr. Kilian Piettre Dr. Yannick Coppel Dr. Eric Beche Dr. Jérôme Esvan Vincent Collière Dr. Bruno Chaudret Dr. Pierre Fau 《Angewandte Chemie (International ed. in English)》2016,55(9):3027-3030
With the ever increasing miniaturization in microelectronic devices, new deposition techniques are required to form high‐purity metal oxide layers. Herein, we report a liquid route to specifically produce thin and conformal amorphous manganese oxide layers on silicon substrate, which can be transformed into a manganese silicate layer. The undesired insertion of carbon into the functional layers is avoided through a solution metal–organic chemistry approach named Solution Layer Deposition (SLD). The growth of a pure manganese oxide film by SLD takes place through the decoordination of ligands from a metal–organic complex in mild conditions, and coordination of the resulting metal atoms on a silica surface. The mechanism of this chemical liquid route has been elucidated by solid‐state 29Si MAS NMR, XPS, SIMS, and HRTEM. 相似文献
992.
A Bis(Diphosphanyl N‐Heterocyclic Carbene) Gold Complex: A Synthon for Luminescent Rigid AuAg2 Arrays and Au5 and Cu6 Double Arrays 下载免费PDF全文
Pengfei Ai Dr. Matteo Mauro Prof. Luisa De Cola Dr. Andreas A. Danopoulos Dr. Pierre Braunstein 《Angewandte Chemie (International ed. in English)》2016,55(10):3338-3341
A mononuclear bis(NHC)/AuI (NHC=N‐heterocyclic carbene) cationic complex with a rigid bis(phosphane)‐functionalized NHC ligand (PCNHCP) was used to construct linear Au3 and Ag2Au arrays, a Au5 cluster with two intersecting crosslike Au3 arrays, and an unprecedented Cu6 complex with two parallel Cu3 arrays. The impact of metallophilic interactions on photoluminescence was studied experimentally. 相似文献
993.
Samuel F. Cousin Dr. Pavel Kadeřávek Baptiste Haddou Dr. Cyril Charlier Thorsten Marquardsen Jean‐Max Tyburn Dr. Pierre‐Alain Bovier Dr. Frank Engelke Dr. Werner Maas Prof. Dr. Geoffrey Bodenhausen Dr. Philippe Pelupessy Prof. Dr. Fabien Ferrage 《Angewandte Chemie (International ed. in English)》2016,55(34):9886-9889
Nuclear magnetic resonance (NMR) studies have benefited tremendously from the steady increase in the strength of magnetic fields. Spectacular improvements in both sensitivity and resolution have enabled the investigation of molecular systems of rising complexity. At very high fields, this progress may be jeopardized by line broadening, which is due to chemical exchange or relaxation by chemical shift anisotropy. In this work, we introduce a two‐field NMR spectrometer designed for both excitation and observation of nuclear spins in two distinct magnetic fields in a single experiment. NMR spectra of several small molecules as well as a protein were obtained, with two dimensions acquired at vastly different magnetic fields. Resonances of exchanging groups that are broadened beyond recognition at high field can be sharpened to narrow peaks in the low‐field dimension. Two‐field NMR spectroscopy enables the measurement of chemical shifts at optimal fields and the study of molecular systems that suffer from internal dynamics, and opens new avenues for NMR spectroscopy at very high magnetic fields. 相似文献
994.
Cover Picture: Densely Packed Hydrophobic Clustering: Encapsulated Valerates Form a High‐Temperature‐Stable {Mo132} Capsule System (Angew. Chem. Int. Ed. 23/2016) 下载免费PDF全文
995.
Pierre?Pilon Daniel?Dion Marie-Josée?BinetteEmail authorView authors OrcID profile 《International Journal for Ion Mobility Spectrometry》2016,19(2-3):113-119
Ion mobility spectrometry (IMS) is a well known field technique for the detection of various materials such as explosives and narcotics. IMS has been used for the detection and identification of nicotine, and this paper describes a simple preparation method and analysis using an Ionscan 500DT which could be used in a field environment for the detection of nicotine in e-liquids. E-liquids containing nicotine are presently a topic of much debate in many countries and their shipment across the Canadian border is prohibited. The method described here would allow border officers or any other operators of IMS instruments to use this technique to correctly determine the presence or absence of nicotine in the e-liquid; this would allow the timely importation of the e-liquids with no nicotine and restrict the laboratory analysis only to those liquids containing nicotine. The IMS method has been used on a number of samples received from manufacturers of e-liquids as well as samples seized at the border. The results of the IMS analysis correspond well with those obtained using a Gas Chromatograph – Mass Spectrometer (GC-MS) method of analysis for nicotine. 相似文献
996.
Let \({\pi(x)}\) be the number of primes not exceeding x. We produce new explicit bounds for \({\pi(x)}\) and we use them to obtain a fine frame for the remainder term in the asymptotic formula of the sum \({\sum_{2\leq n\leq x}1/\pi(n)}\). 相似文献
997.
We address the question of determining the eigenvalues \({\lambda_{n}}\) (listed in nondecreasing order, with multiplicities) for which Courant’s nodal domain theorem is sharp i.e., for which there exists an associated eigenfunction with \({n}\) nodal domains (Courant-sharp eigenvalues). Following ideas going back to Pleijel (1956), we prove that the only Courant-sharp eigenvalues of the flat equilateral torus are the first and second, and that the only Courant-sharp Dirichlet eigenvalues of the equilateral triangle are the first, second, and fourth eigenvalues. In the last section we sketch similar results for the right-angled isosceles triangle and for the hemiequilateral triangle. 相似文献
998.
Audrey Boutonnet Arnaud Morin Pierre Petit Patricia Vicendo Véréna Poinsot François Couderc 《Analytica chimica acta》2016
Pulsed lasers are widely used in capillary electrophoresis (CE) studies to provide laser induced fluorescence (LIF) detection. Unfortunately pulsed lasers do not give linear calibration curves over a wide range of concentrations. While this does not prevent their use in CE/LIF studies, the non-linear behavior must be understood. Using 7-hydroxycoumarin (7-HC) (10–5000 nM), Tamra (10–5000 nM) and tryptophan (1–200 μM) as dyes, we observe that continuous lasers and LEDs result in linear calibration curves, while pulsed lasers give polynomial ones. The effect is seen with both visible light (530 nm) and with UV light (355 nm, 266 nm). In this work we point out the formation of byproducts induced by pulsed laser upon irradiation of 7-HC. Their separation by CE using two Zeta LIF detectors clearly shows that this process is related to the first laser detection. All of these photodegradation products can be identified by an ESI-/MS investigation and correspond to at least two 7HC dimers. By using the photodegradation model proposed by Heywood and Farnsworth (2010) and by taking into account the 7-HC results and the fact that in our system we do not have a constant concentration of fluorophore, it is possible to propose a new photochemical model of fluorescence in LIF detection. The model, like the experiment, shows that it is difficult to obtain linear quantitation curves with pulsed lasers while UV-LEDs used in continuous mode have this advantage. They are a good alternative to UV pulsed lasers. An application involving the separation and linear quantification of oligosaccharides labeled with 2-aminobezoic acid is presented using HILIC and LED (365 nm) induced fluorescence. 相似文献
999.
Cover Picture: Fast‐Geomimicking using Chemistry in Supercritical Water (Angew. Chem. Int. Ed. 34/2016) 下载免费PDF全文
1000.
Dr. Zhengxing Qin Dr. Georgian Melinte Prof. Jean‐Pierre Gilson Prof. Maguy Jaber Prof. Krassimir Bozhilov Dr. Philippe Boullay Dr. Svetlana Mintova Prof. Ovidiu Ersen Dr. Valentin Valtchev 《Angewandte Chemie (International ed. in English)》2016,55(48):15049-15052
Zeolites are widely used in many commercial processes, mostly as catalysts or adsorbents. Understanding their intimate structure at the nanoscale is the key to control their properties and design the best materials for their ever increasing uses. Herein, we report a new and controllable fluoride treatment for the non‐discriminate extraction of zeolite framework cations. This sheds new light on the sub‐structure of commercially relevant zeolite crystals: they are segmented along defect zones exposing numerous nanometer‐sized crystalline domains, separated by low‐angle boundaries, in what were apparent single‐crystals. The concentration, morphology, and distribution of such domains analyzed by electron tomography indicate that this is a common phenomenon in zeolites, independent of their structure and chemical composition. This is a milestone to better understand their growth mechanism and rationally design superior catalysts and adsorbents. 相似文献