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1.
Olesia I. Kucheriv Dr. Sergii I. Shylin Valerii Y. Sirenko Dr. Vadim Ksenofontov Prof. Wolfgang Tremel Dr. Ioan-Andrei Dascălu Dr. Sergiu Shova Dr. Il'ya A. Gural'skiy 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(44):e202200924
Spin-crossover complexes with multistep transitions attract much attention due to their potential applications as multi-switches and for data storage. A four-step spin crossover is observed in the new iron(II)-based cyanometallic guest-free framework compound Fe(2-ethoxypyrazine)2{Ag(CN)2}2 during the transition from the low-spin to the high-spin state. A reverse process occurs in three steps. Crystallographic studies reveal an associated stepwise evolution of the crystal structures. Multiple transitions in the reported complex originate from distinct FeII sites which exist due to the packing of the ligand with a bulky substituent. 相似文献
2.
Peez Nadine Becker Jochen Ehlers Sonja M. Fritz Melanie Fischer Christian B. Koop Jochen H. E. Winkelmann Carola Imhof Wolfgang 《Analytical and bioanalytical chemistry》2019,411(28):7603-7603
Analytical and Bioanalytical Chemistry - The original version of this article contained a mistake. 相似文献
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Eva Dehling Jennifer Rüschenbaum Julia Diecker Wolfgang Drner Henning D. Mootz 《Chemical science》2020,11(33):8945
Nonribosomal peptide synthetases (NRPSs) are large, multi-modular enzyme templates for the biosynthesis of important peptide natural products. Modules are composed of a set of semi-autonomous domains that facilitate the individual reaction steps. Only little is known about the existence and relevance of a higher-order architecture in these mega-enzymes, for which contacts between non-neighboring domains in three-dimensional space would be characteristic. Similarly poorly understood is the structure of communication-mediating (COM) domains that facilitate NRPS subunit docking at the boundaries between epimerization and condensation domains. We investigated a COM domain pair in a minimal two module NRPS using genetically encoded photo-crosslinking moieties in the N-terminal acceptor COM domain. Crosslinks into the C-terminal donor COM domain of the partner module resulted in protein products with the expected migration behavior on SDS-PAGE gels corresponding to the added molecular weight of the proteins. Additionally, an unexpected apparent high-molecular weight crosslink product was revealed by mass spectrometric analysis to represent a T-form isomer with branched connectivity of the two polypeptide chains. Synthesis of the linear L-form and branched T-form isomers by click chemistry confirmed this designation. Our data revealed a surprising spatial proximity between the acceptor COM domain and the functionally unrelated small subdomain of the preceding adenylation domain. These findings provide an insight into three-dimensional domain arrangements in NRPSs in solution and suggest the described photo-crosslinking approach as a promising tool for the systematic investigation of their higher-order architecture.Photo-crosslink analysis reveals unexpected insights into the higher-order architecture of NRPS and the nature of crosslink isomers. 相似文献
6.
Mohammad El-khateeb Hassan Abul-Futouh Hadil Alshurafa Helmar Görls Wolfgang Weigand 《应用有机金属化学》2020,34(11):e5940
Substitution of carbonyl ligands of the hydrogenase model complex [Fe2(μ-SeCH2CH(Me)CH2Se-μ)(CO)6] ( A ), by 1,1′-bis (diphenylphosphino)ferrocene (dppf), 1,2-bis (diphenylphosphino)benzene (dppbz) or 1,2-bis (diphenylphosphino)acetylene (dppac) is investigated. It is found that the reaction product depends on the diphosphine used. In the case of dppf, the product is an intramolecular bridged disubstituted complex [Fe2{μ-SeCH2CH(Me)CH2Se-μ}(CO)4{μ,κ1,κ1(P,P)-dppf}] ( 1 ), while the dppac-reaction produces an intermolecular bridged tetra-iron model [Fe2{μ-SeCH2CH(Me)CH2Se-μ}(CO)5]2{μ,κ1,κ1(P,P)-dppac} ( 2 ). However, the dppbz-reaction gives [Fe2{μ-SeCH2CH(Me)CH2Se-μ}(CO)4{κ2(P,P)-dppbz}] ( 3 ) in which the dppbz ligand is bonded to one Fe atom in a chelated manner. The newly prepared complexes ( 1 – 3 ) have been characterized by elemental analysis, IR, 1H-, 13C{H}-, 31P{H}-, 77Se{H}-NMR spectroscopy and X-ray structure determination. The electrochemical behavior of 2 and 3 , in absence and presence of acid, is described by cyclic voltammetric measurements in CH2Cl2. 相似文献
7.
Dr. Peiyu Ge Dr. Mohamad Hojeij Dr. Micheál D. Scanlon Prof. Hubert H. Girault 《Chemphyschem》2020,21(24):2630-2633
H2 may be evolved biphasically using a polarised liquid|liquid interface, acting as a “proton pump”, in combination with organic soluble metallocenes as electron donors. Sustainable H2 production requires methodologies to recycle the oxidised donor. Herein, the photo-recycling of decamethylferrocenium cations (DcMFc+) using aqueous core-shell semiconductor CdSe@CdS nanoparticles is presented. Negative polarisation of the liquid|liquid interface is required to extract DcMFc+ to the aqueous phase. This facilitates the efficient capture of electrons by DcMFc+ on the surface of the photo-excited CdSe@CdS nanoparticles, with hydrophobic DcMFc subsequently partitioning back to the organic phase and resetting the system. TiO2 (P25) and CdSe semiconductor nanoparticles failed to recycle DcMFc+ due to their lower conduction band energy levels. During photo-recycling, CdS (on CdSe) may be self-oxidised and photo-corrode, instead of water acting as the hole scavenger. 相似文献
8.
Square‐Planar Ruthenium(II) Complexes: Control of Spin State by Pincer Ligand Functionalization 下载免费PDF全文
Dr. Bjorn Askevold Dr. Marat M. Khusniyarov Dr. Wolfgang Kroener Dr. Klaus Gieb Prof. Paul Müller Dr. Eberhardt Herdtweck Dr. Frank W. Heinemann Dr. Martin Diefenbach Prof. Max C. Holthausen Veacheslav Vieru Prof. Liviu F. Chibotaru Prof. Sven Schneider 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(2):579-589
Functionalization of the PNP pincer ligand backbone allows for a comparison of the dialkyl amido, vinyl alkyl amido, and divinyl amido ruthenium(II) pincer complex series [RuCl{N(CH2CH2PtBu2)2}], [RuCl{N(CHCHPtBu2)(CH2CH2PtBu2)}], and [RuCl{N(CHCHPtBu2)2}], in which the ruthenium(II) ions are in the extremely rare square‐planar coordination geometry. Whereas the dialkylamido complex adopts an electronic singlet (S=0) ground state and energetically low‐lying triplet (S=1) state, the vinyl alkyl amido and the divinyl amido complexes exhibit unusual triplet (S=1) ground states as confirmed by experimental and computational examination. However, essentially non‐magnetic ground states arise for the two intermediate‐spin complexes owing to unusually large zero‐field splitting (D>+200 cm?1). The change in ground state electronic configuration is attributed to tailored pincer ligand‐to‐metal π‐donation within the PNP ligand series. 相似文献
9.
Thomas Wittmann Dr. Renée Siegel Nele Reimer Dr. Wolfgang Milius Prof. Dr. Norbert Stock Prof. Dr. Jürgen Senker 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(1):314-323
The resistance of metal–organic frameworks towards water is a very critical issue concerning their practical use. Recently, it was shown for microporous MOFs that the water stability could be increased by introducing hydrophobic pendant groups. Here, we demonstrate a remarkable stabilisation of the mesoporous MOF Al‐MIL‐101‐NH2 by postsynthetic modification with phenyl isocyanate. In this process 86 % of the amino groups were converted into phenylurea units. As a consequence, the long‐term stability of Al‐MIL‐101‐URPh in liquid water could be extended beyond a week. In water saturated atmospheres Al‐MIL‐101‐URPh decomposed at least 12‐times slower than the unfunctionalised analogue. To study the underlying processes both materials were characterised by Ar, N2 and H2O sorption measurements, powder X‐ray diffraction, thermogravimetric and chemical analysis as well as solid‐state NMR and IR spectroscopy. Postsynthetic modification decreased the BET equivalent surface area from 3363 to 1555 m2 g?1 for Al‐MIL‐101‐URPh and reduced the mean diameters of the mesopores by 0.6 nm without degrading the structure significantly and reducing thermal stability. In spite of similar water uptake capacities, the relative humidity‐dependent uptake of Al‐MIL‐101‐URPh is slowed and occurs at higher relative humidity values. In combination with 1H‐27Al D ‐HMQC NMR spectroscopy experiments this favours a shielding mechanism of the Al clusters by the pendant phenyl groups and rules out pore blocking. 相似文献
10.
Benjamin A. R. Günther Dr. Sebastian Höfener Dr. Ute Zschieschang Prof. Dr. Hubert Wadepohl Dr. Hagen Klauk Prof. Dr. Lutz H. Gade 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(64):14669-14678
A new synthesis of tetraazaperopyrenes (TAPPs) starting from a halogenated perylene derivative 3,4,9,10- tetrabromo-1,6,7,12-tetrachloroperylene ( 1 ) gave access to bay-substituted TAPPs for the first time. Selective lithiation of the bromine-positions and subsequent addition of tosyl azide led to the formation of the tetraazidotetrachloroperylene ( 2 ), which was subsequently reduced by addition of sodium borohydride to the corresponding tetraaminotetrachloroperylene ( 3 ). Oxidation to its semiquinoidal form 4 and subsequent cyclization with acid chlorides gave rise to a series of bay-chlorinated TAPPs. Whereas the aromatic core of the previously studied ortho-substituted TAPPs was found to be planar, the steric pressure of the two chlorine substituents on each side leads to the twist of the peropyrene core of approximately 30 degrees, a structural feature also observed in other bay-substituted perylene derivatives. An experimental and computational analysis reveals that introducing chloride substituents at these positions leads to slightly increased electron affinities (EA) enabling the selective generation and characterization of the reduced mono-anionic radicals and closed shell di-anionic species. These anions were isolated and characterized by UV/Vis spectroscopy and EPR or NMR, respectively. Processing of the bay-chlorinated TAPPs in n-channel organic TFTs revealed electron mobilities of 0.001 to 0.003 cm2 V−1 s−1. These reduced electron mobilities compared to the ortho-halogenated TAPPs are thought to be rooted in the less densely packed solid-state structures. 相似文献