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991.
A Novel Bismuth‐Based Metal–Organic Framework for High Volumetric Methane and Carbon Dioxide Adsorption
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Mathew Savage Dr. Sihai Yang Dr. Mikhail Suyetin Prof. Dr. Elena Bichoutskaia Dr. William Lewis Prof. Dr. Alexander J. Blake Sarah A. Barnett Prof. Dr. Martin Schröder 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(26):8024-8029
Solvothermal reaction of H4L (L=biphenyl‐3,3′,5,5′‐tetracarboxylate) and Bi(NO3)3 ? (H2O)5 in a mixture of DMF/MeCN/H2O in the presence of piperazine and nitric acid at 100 °C for 10 h affords the solvated metal–organic polymer [Bi2(L)1.5(H2O)2] ? (DMF)3.5 ? (H2O)3 (NOTT‐220‐solv). A single crystal X‐ray structure determination confirms that it crystallises in space group P2/c and has a neutral and non‐interpenetrated structure comprising binuclear {Bi2} centres bridged by tetracarboxylate ligands. NOTT‐220‐solv shows a 3,6‐connected network having a framework topology with a {4 ? 62}2{42 ? 65 ? 88}{62 ? 8} point symbol. The desolvated material NOTT‐220a shows exceptionally high adsorption uptakes for CH4 and CO2 on a volumetric basis at moderate pressures and temperatures with a CO2 uptake of 553 g L?1 (20 bar, 293 K) with a saturation uptake of 688 g L?1 (1 bar, 195 K). The corresponding CH4 uptake was measured as 165 V(STP)/V (20 bar, 293 K) and 189 V(STP/V) (35 bar, 293 K) with a maximum CH4 uptake for NOTT‐220a recorded at 20 bar and 195 K to be 287 V(STP)/V, while H2 uptake of NOTT‐220a at 20 bar, 77 K is 42 g L?1. These gas uptakes have been modelled by grand canonical Monte Carlo (GCMC) and density functional theory (DFT) calculations, which confirm the experimental data and give insights into the nature of the binding sites of CH4 and CO2 in this porous hybrid material. 相似文献
992.
William Neil Gilfillan Lalehvash Moghaddam William O. S. Doherty 《Cellulose (London, England)》2014,21(4):2695-2712
This paper reports on the results of using unbleached sugar cane bagasse nanofibres (average diameter 26.5 nm; aspect ratio 247 assuming a dry fibre density of 1,500 kg/m3) to improve the physico-chemical properties of starch-based films. The addition of bagasse nanofibres (2.5 to 20 wt%) to modified potato starch (i.e. soluble starch) reduced the moisture uptake by up to 17 % at 58 % relative humidity. The film’s tensile strength and Young’s modulus increased by up to 100 % (3.1 to 6.2 MPa) and 300 % (66.3 to 198.3 MPa) respectively with 10 and 20 wt% fibre addition. However, the strain at yield dropped by 50 % for the film containing 10 wt% fibre. Models for composite materials were used to account for the strong interactions between the nanofibres and the starch matrix. The storage and loss moduli as well as the glass transition temperature (Tg) obtained from dynamic mechanical thermal analysis, were increased with the starch-nanofibre films indicating decreased starch chain mobility due to the interacting effect of the nanofibres. Evidence of the existence of strong interactions between the starch matrix and the nanofibres was revealed from detailed Fourier transform infra-red and scanning electron microscopic evaluation. 相似文献
993.
A Plausible Simultaneous Synthesis of Amino Acids and Simple Peptides on the Primordial Earth
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Eric T. Parker Dr. Manshui Zhou Dr. Aaron S. Burton Dr. Daniel P. Glavin Dr. Jason P. Dworkin Prof. Dr. Ramanarayanan Krishnamurthy Prof. Dr. Facundo M. Fernández Prof. Dr. Jeffrey L. Bada 《Angewandte Chemie (International ed. in English)》2014,53(31):8132-8136
Following his seminal work in 1953, Stanley Miller conducted an experiment in 1958 to study the polymerization of amino acids under simulated early Earth conditions. In the experiment, Miller sparked a gas mixture of CH4, NH3, and H2O, while intermittently adding the plausible prebiotic condensing reagent cyanamide. For unknown reasons, an analysis of the samples was not reported. We analyzed the archived samples for amino acids, dipeptides, and diketopiperazines by liquid chromatography, ion mobility spectrometry, and mass spectrometry. A dozen amino acids, 10 glycine‐containing dipeptides, and 3 glycine‐containing diketopiperazines were detected. Miller’s experiment was repeated and similar polymerization products were observed. Aqueous heating experiments indicate that Strecker synthesis intermediates play a key role in facilitating polymerization. These results highlight the potential importance of condensing reagents in generating diversity within the prebiotic chemical inventory. 相似文献
994.
Inside Back Cover: Site‐Selective Synthesis of Janus‐type Metal‐Organic Framework Composites (Angew. Chem. Int. Ed. 15/2014)
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995.
Sepideh Afsari Dr. Zhihai Li Prof. Dr. Eric Borguet 《Angewandte Chemie (International ed. in English)》2014,53(37):9771-9774
The conductivity of a single aromatic ring, perpendicular to its plane, is determined using a new strategy under ambient conditions and at room temperature by a combination of molecular assembly, scanning tunneling microscopy (STM) imaging, and STM break junction (STM‐BJ) techniques. The construction of such molecular junctions exploits the formation of highly ordered structures of flat‐oriented mesitylene molecules on Au(111) to enable direct tip/π contacts, a result that is not possible by conventional methods. The measured conductance of Au/π/Au junction is about 0.1 Go , two orders of magnitude higher than the conductance of phenyl rings connected to the electrodes by standard anchoring groups. Our experiments suggest that long‐range ordered structures, which hold the aromatic ring in place and parallel to the surface, are essential to increase probability of the formation of orientation‐controlled molecular junctions. 相似文献
996.
Eric Mädl Dr. Mikhail V. Butovskii Dr. Gábor Balázs Dr. Eugenia V. Peresypkina Dr. Alexander V. Virovets Michael Seidl Prof. Dr. Manfred Scheer 《Angewandte Chemie (International ed. in English)》2014,53(29):7643-7646
Unprecedented functionalized products with an η4‐P5 ring are obtained by the reaction of [Cp*Fe(η5‐P5)] ( 1 ; Cp*=η5‐C5Me5) with different nucleophiles. With LiCH2SiMe3 and LiNMe2, the monoanionic products [Cp*Fe(η4‐P5CH2SiMe3)]? and [Cp*Fe(η4‐P5NMe2)]?, respectively, are formed. The reaction of 1 with NaNH2 leads to the formation of the trianionic compound [{Cp*Fe(η4‐P5)}2N]3?, whereas the reaction with LiPH2 yields [Cp*Fe(η4‐P5PH2)]? as the main product, with {[Cp*Fe(η4‐P5)]2PH}2? as a byproduct. The calculated energy profile of the reactions provides a rationale for the formation of the different products. 相似文献
997.
Dr. Wawrzyniec Kaszub Andrea Marino Dr. Maciej Lorenc Prof. Eric Collet Prof. Elena G. Bagryanskaya Prof. Evgeny V. Tretyakov Prof. Victor I. Ovcharenko Prof. Matvey V. Fedin 《Angewandte Chemie (International ed. in English)》2014,53(40):10636-10640
Molecular compounds with photoswitchable magnetic properties have been intensively investigated over the last decades due to their prospective applications in nanoelectronics, sensing and magnetic data storage. The family of copper‐nitroxide‐based molecular magnets represents a new promising type of photoswitchable compounds. We report the first study of these appealing systems using femtosecond optical spectroscopy. We unveil the mechanism of ultrafast (<50 fs) spin state photoswitching and establish its principal differences compared to other photoswitchable magnets. On this basis, we propose potential advantages of copper‐nitroxide‐based molecular magnets for the future design of ultrafast magnetic materials. 相似文献
998.
The Ketimide Ligand is Not Just an Inert Spectator: Heteroallene Insertion Reactivity of an Actinide–Ketimide Linkage in a Thorium Carbene Amide Ketimide Complex
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Dr. Erli Lu Dr. William Lewis Prof. Alexander J. Blake Prof. Stephen T. Liddle 《Angewandte Chemie (International ed. in English)》2014,53(35):9356-9359
The ketimide anion R2C?N? is an important class of chemically robust ligand that binds strongly to metal ions and is considered ideal for supporting reactive metal fragments due to its inert spectator nature; this contrasts with R2N? amides that exhibit a wide range of reactivities. Here, we report the synthesis and characterization of a rare example of an actinide ketimide complex [Th(BIPMTMS){N(SiMe3)2}(N?CPh2)] [ 2 , BIPMTMS=C(PPh2NSiMe3)2]. Complex 2 contains Th?Ccarbene, Th? Namide and Th? Nketimide linkages, thereby presenting the opportunity to probe the preferential reactivity of these linkages. Importantly, reactivity studies of 2 with unsaturated substrates shows that insertion reactions occur preferentially at the Th? Nketimide bond rather than at the Th?Ccarbene or Th? Namide bonds. This overturns the established view that metal‐ketimide linkages are purely inert spectators. 相似文献
999.
Interrupted Imino‐Nazarov Cyclization of 1‐Aminopentadienyl Cation and Related Cascade Process
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Ronny William Siming Wang Feiqing Ding Elise Nerissa Arviana Prof. Dr. Xue‐Wei Liu 《Angewandte Chemie (International ed. in English)》2014,53(40):10742-10746
Facile 4π conrotatory imino‐Nazarov cyclization of a 1‐aminopentadienyl cation generated from condensation an aldehyde and secondary aniline in the presence of a catalytic amount of a Lewis acid has been developed. Silver(I)‐catalyzed intramolecular arene trapping of the resulting cyclic oxyallyl cation leads to formation of tricyclic indoline‐fused cyclopentanone. The use of lanthanide salts allows transformation after the initial trapping to afford tetrahydroquinoline‐fused cyclopentenone in a concise manner. 相似文献
1000.
Molecularly Precise Dendrimer–Drug Conjugates with Tunable Drug Release for Cancer Therapy
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Dr. Zhuxian Zhou Dr. Xinpeng Ma Dr. Caitlin J. Murphy Dr. Erlei Jin Dr. Qihang Sun Prof. Youqing Shen Edward A. Van Kirk Prof. William J. Murdoch 《Angewandte Chemie (International ed. in English)》2014,53(41):10949-10955
The structural preciseness of dendrimers makes them perfect drug delivery carriers, particularly in the form of dendrimer–drug conjugates. Current dendrimer–drug conjugates are synthesized by anchoring drug and functional moieties onto the dendrimer peripheral surface. However, functional groups exhibiting the same reactivity make it impossible to precisely control the number and the position of the functional groups and drug molecules anchored to the dendrimer surface. This structural heterogeneity causes variable pharmacokinetics, preventing such conjugates to be translational. Furthermore, the highly hydrophobic drug molecules anchored on the dendrimer periphery can interact with blood components and alter the pharmacokinetic behavior. To address these problems, we herein report molecularly precise dendrimer–drug conjugates with drug moieties buried inside the dendrimers. Surprisingly, the drug release rates of these conjugates were tailorable by the dendrimer generation, surface chemistry, and acidity. 相似文献