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71.
Luminescent Carbon Nanodots: Emergent Nanolights 总被引:2,自引:0,他引:2
Dr. Sheila N. Baker Dr. Gary A. Baker 《Angewandte Chemie (International ed. in English)》2010,49(38):6726-6744
Similar to its popular older cousins the fullerene, the carbon nanotube, and graphene, the latest form of nanocarbon, the carbon nanodot, is inspiring intensive research efforts in its own right. These surface‐passivated carbonaceous quantum dots, so‐called C‐dots, combine several favorable attributes of traditional semiconductor‐based quantum dots (namely, size‐ and wavelength‐dependent luminescence emission, resistance to photobleaching, ease of bioconjugation) without incurring the burden of intrinsic toxicity or elemental scarcity and without the need for stringent, intricate, tedious, costly, or inefficient preparation steps. C‐dots can be produced inexpensively and on a large scale (frequently using a one‐step pathway and potentially from biomass waste‐derived sources) by many approaches, ranging from simple candle burning to in situ dehydration reactions to laser ablation methods. In this Review, we summarize recent advances in the synthesis and characterization of C‐dots. We also speculate on their future and discuss potential developments for their use in energy conversion/storage, bioimaging, drug delivery, sensors, diagnostics, and composites. 相似文献
72.
Fluorescence correlation spectroscopy (FCS) measurements have been performed in order to determine the translational diffusion coefficients of three differently charged fluorescent probes (cationic: rhodamine 6G, neutral: 4-dicyanomethylene-2-methyl-6-p-dimethylaminostyryl-4-H-pyran, DCM, and anionic: fluorescein) dissolved within the common room temperature ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate, [bmim][PF6]. These experiments demonstrate that FCS is a rapid, sensitive, precise (typical RSD from 4-8%), and low-consumption screening tool for the determination of analyte mobility within microliter ionic liquid samples. 相似文献
73.
Treatment of [MI2(CO)3(NCMe)2] with two equivalents of 4,4-bipyridine (4,4-bipy) in CH2Cl2 at room temperature gave the MeCN displaced products, [MI2(CO)3(4,4-bipy-N)2] (1) and (2). Equimolar amounts of [MI2(CO)3(NCMe)2] and L (L = PPh3, AsPh3 or SbPh3) react to give [MI2(CO)3(NCMe)L], which when reacted in situ with 4,4-bipy yield the new complexes, [MI2(CO)3(4,4-bipy-N)L] (3)–(8). Reaction of equimolar quantities of [WI2(CO)(NCMe)(
2-RC2R)2] (R = Me or Ph) and 4,4-bipy gave the new bis(alkyne) complexes, [WI2(CO)(4,4-bipy-N)(
2-RC2R)2] (9) and (10). Treatment of [MI2(CO)3(NCMe)2] with two equivalents of (9) or (10) in CH2Cl2 at room temperature affords the bimetallic complexes, [MI2(CO)3{WI2(CO)(4,4-bipy-N,N)(
2-RC2R)2}2] (11)–(14). Equimolar quantities of [MI2(CO)3(NCMe)(PPh3)] (prepared in situ) and (9) or (10), react to give the 4,4-bipy-bridged complexes, [MI2(CO)3{WI2(CO)(4,4-bipy-N,N)(
2-RC2R)2}(PPh3)] (15)–(18). All the new complexes, (1)–(18) were characterised by elemental analysis (C, H and N), i.r. and 1H-n.m.r. spectroscopy. 相似文献
74.
We present details of our efficient implementation of full accuracy unrestricted open‐shell second‐order canonical Møller–Plesset (MP2) energies, both serial and parallel. The algorithm is based on our previous restricted closed‐shell MP2 code using the Saebo–Almlöf direct integral transformation. Depending on system details, UMP2 energies take from less than 1.5 to about 3.0 times as long as a closed‐shell RMP2 energy on a similar system using the same algorithm. Several examples are given including timings for some large stable radicals with 90+ atoms and over 3600 basis functions. © 2011 Wiley Periodicals, Inc. J Comput Chem, 2011 相似文献
75.
Christoph Kieninger Joseph A. Baker Maren Podewitz Klaus Wurst Steffen Jockusch Andrew D. Lawrence Evelyne Deery Karl Gruber Klaus R. Liedl Martin J. Warren Bernhard Krutler 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(41):14710-14714
Replacing the central cobalt ion of vitamin B12 by other metals has been a long‐held aspiration within the B12‐field. Herein, we describe the synthesis from hydrogenobyric acid of zincobyric acid ( Znby ) and zincobalamin ( Znbl ), the Zn‐analogues of the natural cobalt‐corrins cobyric acid and vitamin B12, respectively. The solution structures of Znby and Znbl were studied by NMR‐spectroscopy. Single crystals of Znby were produced, providing the first X‐ray crystallographic structure of a zinc corrin. The structures of Znby and of computationally generated Znbl were found to resemble the corresponding CoII‐corrins, making such Zn‐corrins potentially useful for investigations of B12‐dependent processes. The singlet excited state of Znby had a short life‐time, limited by rapid intersystem crossing to the triplet state. Znby allowed the unprecedented observation of a corrin triplet (ET=190 kJ mol?1) and was found to be an excellent photo‐sensitizer for 1O2 (ΦΔ=0.70). 相似文献
76.
The article to which this Erratum refers was published in Journal of Computational Chemistry (2004) 25(13) 1623–1629 相似文献
77.
Synthesis of poly(2-hydroxyethyl methacrylate) (PHEMA) brushes from the inside of silica capillaries by surface-initiated atom transfer radical polymerization (ATRP) yields unique stationary phases for open-tubular capillary electrochromatography (OT-CEC). Although PHEMA brushes have only a small effect on the separation of a set of phenols and anilines, derivatization of PHEMA with ethylenediamine (en) allows baseline resolution of several anilines that co-elute from bare silica capillaries. Derivatization of PHEMA with octanoyl chloride (C8-PHEMA films) affords even better resolution in the separation of a series of phenols and anilines. Increasing the thickness of C8-PHEMA coatings by a factor of 2 enhances resolution for several solute pairs, presumably because of an increase in the effective stationary phase to mobile phase volume ratio. Thus, this work demonstrates that thick polymer brushes provide a tunable stationary phase with a much larger phase ratio than is available from monolayer wall coatings. Through appropriate choice of derivatizing reagents, these polymer brushes should allow separation of a wide range of neutral molecules as well as compounds with similar electrophoretic mobilities. 相似文献
78.
Accurate data on transport properties such as viscosity are essential in plant and process design involving ionic liquids. In this study, we determined the absolute viscosity of the ionic liquid + water system at water mole fractions from 0 to 0.25 for three 1-alkyl-3-methylimidazolium ionic liquids: 1-butyl-3-methylimidazolium hexafluorophosphate, 1-butyl-3-methylimidazolium bis(trifluoromethane sulfonyl)imide and 1-ethyl-3-methylimidazolium bis(trifluoromethane sulfonyl)imide. In each case, the excimer to monomer ratio for 1,m-bis(1-pyrenyl)alkanes (m= 3 or 10) was found to increase linearly with the mole fraction of water. Of the probes studied only PRODAN and rhodamine 6G, both of which have the ability to participate in hydrogen bonding, exhibited Perrin hydrodynamic behavior in the lower viscosity bis(trifluoromethane sulfonyl)imides. As a result, these probes allow for the extrapolation of the absolute viscosity of the ionic liquid mixture from the experimental fluorescence steady-state polarization values. 相似文献
79.
80.
Sem DS Bertolaet B Baker B Chang E Costache AD Coutts S Dong Q Hansen M Hong V Huang X Jack RM Kho R Lang H Ma CT Meininger D Pellecchia M Pierre F Villar H Yu L 《Chemistry & biology》2004,11(2):185-194
Genomics-driven growth in the number of enzymes of unknown function has created a need for better strategies to characterize them. Since enzyme inhibitors have traditionally served this purpose, we present here an efficient systems-based inhibitor design strategy, enabled by bioinformatic and NMR structural developments. First, we parse the oxidoreductase gene family into structural subfamilies termed pharmacofamilies, which share pharmacophore features in their cofactor binding sites. Then we identify a ligand for this site and use NMR-based binding site mapping (NMR SOLVE) to determine where to extend a combinatorial library, such that diversity elements are directed into the adjacent substrate site. The cofactor mimic is reused in the library in a manner that parallels the reuse of cofactor domains in the oxidoreductase gene family. A library designed in this manner yielded specific inhibitors for multiple oxidoreductases. 相似文献