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排序方式: 共有174条查询结果,搜索用时 390 毫秒
131.
Alexander Hofmann Conor Pranckevicius Tobias Trster Holger Braunschweig 《Angewandte Chemie (International ed. in English)》2019,58(11):3625-3629
Reactions between BIII species and the novel nucleophilic cyclopentadienyl‐stabilized AlI reagent ( 1 ) result in a diversity of complexes bearing different Al/B oxidation states and coordination geometries. With the triarylborane B(C6F5)3, a simple AlI→BIII adduct is formed. In contrast, a bulky aryldihaloborane undergoes oxidative addition with the formation of a covalent bora‐alane species. With an N‐heterocyclic carbene‐stabilized amino(bromo)borenium ion, a redox reaction was observed, where the product is a borylene‐alane BI→AlIII complex. Additionally, reaction of 1 with BI3 results in complete scrambling of all of the Al/B‐bound substituents, and the formation of a cyclopentadienylboron(I)→AlI3 complex. These latter reactions are the first examples of the reduction of a boron(III) compound to a borylene by a p‐block reagent, and illustrate how subtle changes in the nature of the borane can result in highly divergent reaction outcomes. 相似文献
132.
This study aims to identify two critical components required for pharmaceutical cleaning verification when an FTIR is used: (a) the number of scans required per hard-to-clean location, and (b) the limit of quantification (LOQ) of the FTIR instrument when measuring the surface contamination. The current practice in pharmaceutical manufacturing does not require multiple samples as it is standard practice to collect a single swab sample from a 25 × 25 cm area from a difficult-to-reach area of the manufacturing equipment. However, since the FTIR will only scan a tiny portion of the surface compared to the swab, a sufficient number of samples (data points) are required to provide enough confidence to ensure that the measurement results are close to the true value with a maximum degree of certainty. Similarly, calculating the LOQ for a linear regression could be straightforward. However, complexity arises when the experimental data are complex; in this case, the complexity arises due to the nature of the measurement and the lack of the defined peak in the pre-processed spectra. Therefore, this study uses the practical approach of calculating the sample size and the LOQ. 相似文献
133.
Emmanuel Roussakis Juan Pedro Cascales Haley L. Marks Xiaolei Li Mark Grinstaff Conor L. Evans 《Photochemistry and photobiology》2020,96(2):373-379
Quantification of tissue oxygen partial pressure (pO2) at the skin surface is crucial for diagnostic applications in burns, reconstructive surgeries, diabetic ulcers, etc. Further, current advances in wearable and communications technologies have widened the use of transcutaneous oxygen monitors (TCOM) for home care or even enhance athletic performance. For TCOM technology to find widespread use, devices must function reliably yet independently of changes in environmental conditions, humidity in particular. To this end, we have explored the incorporation of an oxygen-sensing metalloporphyrin within different host matrix materials of different compositions with the goal of overcoming the humidity sensitivity of previously explored oxygen-sensing materials. We developed a tetraethyl orthosilicate (TEOS)-based, highly breathable, oxygen-sensing metalloporphyrin polymer film which responds to changes in oxygenation independent of humidity. 相似文献
134.
Dayne C. Georgiou Bradley D. Stringer Dr. Conor F. Hogan Dr. Peter J. Barnard Dr. David J. D. Wilson Dr. Nicole Holzmann Prof. Dr. Gernot Frenking Dr. Jason L. Dutton 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(8):3377-3386
The attempted synthesis of NHC‐stabilized dicarbon (NHC?C?C?NHC) through deprotonation of a doubly protonated precursor ([NHC?CH?CH?NHC]2+) is reported. Rather than deprotonation, a clean reduction to NHC?CH?CH?NHC is observed with a variety of bases. The apparent resistance towards deprotonation to the target compound led to a reinvestigation of the electronic structure of NHC→C?C←NHC, which showed that the highest occupied molecular orbital/lowest unoccupied molecular orbital (HOMO/LUMO) gap is likely too small to allow for isolation of this species. This is in contrast to the recent isolation of the cyclic alkylaminocarbene analogue (cAAC?C?C?cAAC), which has a large HOMO–LUMO gap. A detailed theoretical study illuminates the differences in electronic structures between these molecules, highlighting another case of the potential advantages of using cAAC rather than NHC as a ligand. The bonding analysis suggests that the dicarbon compounds are well represented in terms of donor–acceptor interactions L→C2←L (L=NHC, cAAC). 相似文献
135.
Efficient fabrication of polymer nanoparticles via sonogashira cross‐linking of linear polymers in dilute solution
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Alka Prasher Conor M. Loynd Bryan T. Tuten Peter G. Frank Danming Chao Erik B. Berda 《Journal of polymer science. Part A, Polymer chemistry》2016,54(1):209-217
The synthesis of single‐chain nanoparticles by palladium‐catalyzed Sonogashira coupling between a terminal alkyne and a di‐halo aryl cross‐linker is reported. Statistical copolymers with trimethylsilyl protected alkyne groups pendent to the linear methacrylate back bones were synthesized using reversible addition‐fragmentation chain transfer polymerization post polymerization de‐protection providing terminal alkyne functionalized linear polymer chains. These linear polymer chains were intramolecularly cross‐linked via bifunctional cross‐linkers. The resulting well‐defined covalently bonded nanoparticles were characterized via triple‐detection size exclusion chromatography where MALS detector provided molecular weight information and viscometric detection characterizes particle size and conformations. The particle size could be readily tuned through polymer molecular weight and by degree of cross‐linking. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 209–217 相似文献
136.
137.
Dr. Olga Ekkert Christopher B. Caputo Conor Pranckevicius Dr. Constantin G. Daniliuc Dr. Gerald Kehr Prof. Dr. Gerhard Erker Prof. Dr. Douglas W. Stephan 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(36):11287-11290
The reactions of the intramolecular frustrated Lewis pair‐adduct Ph2PC(p‐Tol)?C(C6F5)B(C6F5)2(CNtBu) with XeF2 gave Ph2P(F)C(p‐Tol)?C(C6F5)B(F)(C6F5)2 ( 3 ). This species reacts with two equivalents of Al(C6F5)3?C7H8 producing the salt, [Ph2P(F)C(p‐Tol)?C(C6F5)B(C6F5)2][F(Al(C6F5)3)2] ( 4 ), whereas reaction with HSiEt3/B(C6F5)3 gave Ph2P(F)C(p‐Tol)?C(H)B(C6F5)3 ( 5 ). The photolysis of 3 resulted in aromatization affording the phenanthralene derivative Ph2P(F)C(p‐Tol(o‐C6F4))?CB(F)(C6F5)2 ( 6 ). 相似文献
138.
139.
Understanding Electrogenerated Chemiluminescence Efficiency in Blue‐Shifted Iridium(III)‐Complexes: An Experimental and Theoretical Study
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Dr. Gregory J. Barbante Dr. Egan H. Doeven Emily Kerr Timothy U. Connell Dr. Paul S. Donnelly Prof. Jonathan M. White Thais Lópes Sarah Laird Dr. David J. D. Wilson Dr. Peter J. Barnard Dr. Conor F. Hogan Prof. Paul S. Francis 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(12):3322-3332
Compared to tris(2‐phenylpyridine)iridium(III) ([Ir(ppy)3]), iridium(III) complexes containing difluorophenylpyridine (df‐ppy) and/or an ancillary triazolylpyridine ligand [3‐phenyl‐1,2,4‐triazol‐5‐ylpyridinato (ptp) or 1‐benzyl‐1,2,3‐triazol‐4‐ylpyridine (ptb)] exhibit considerable hypsochromic shifts (ca. 25–60 nm), due to the significant stabilising effect of these ligands on the HOMO energy, whilst having relatively little effect on the LUMO. Despite their lower photoluminescence quantum yields compared with [Ir(ppy)3] and [Ir(df‐ppy)3], the iridium(III) complexes containing triazolylpyridine ligands gave greater electrogenerated chemiluminescence (ECL) intensities (using tri‐n‐propylamine (TPA) as a co‐reactant), which can in part be ascribed to the more energetically favourable reactions of the oxidised complex (M+) with both TPA and its neutral radical oxidation product. The calculated iridium(III) complex LUMO energies were shown to be a good predictor of the corresponding M+ LUMO energies, and both HOMO and LUMO levels are related to ECL efficiency. The theoretical and experimental data together show that the best strategy for the design of efficient new blue‐shifted electrochemiluminophores is to aim to stabilise the HOMO, while only moderately stabilising the LUMO, thereby increasing the energy gap but ensuring favourable thermodynamics and kinetics for the ECL reaction. Of the iridium(III) complexes examined, [Ir(df‐ppy)2(ptb)]+ was most attractive as a blue‐emitter for ECL detection, featuring a large hypsochromic shift (λmax=454 and 484 nm), superior co‐reactant ECL intensity than the archetypal homoleptic green and blue emitters: [Ir(ppy)3] and [Ir(df‐ppy)3] (by over 16‐fold and threefold, respectively), and greater solubility in polar solvents. 相似文献
140.
Dr. Emmanuel Roussakis Dr. Zongxi Li Nicholas H. Nowell Dr. Alexander J. Nichols Prof. Dr. Conor L. Evans 《Angewandte Chemie (International ed. in English)》2015,54(49):14728-14731
A new group of “clickable” and brightly emissive metalloporphyrins has been developed for the visualization of oxygenation under ambient light with the naked eye. These alkynyl‐terminated compounds permit the rapid and facile synthesis of oxygen‐sensing dendrimers through azide–alkyne click chemistry. With absorption maxima overlapping with the wavelengths of common commercial laser sources, they are readily applicable to biomedical imaging of tissue oxygenation. An efficient synthetic methodology, featuring the stable trimethylacetyl (pivaloyl) protecting group, is described for their preparation. A paint‐on liquid bandage containing a new, click‐synthesized porphyrin dendrimer has been used to map oxygenation across an ex vivo porcine skin burn model. 相似文献