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101.
David R. Turner Dr. Joshua Strachn‐Hatton Stuart R. Batten Prof. Dr. 《无机化学与普通化学杂志》2009,635(3):439-444
The synthesis and structure of the hydrated mono‐ and di‐potassium salts of benzenepentacarboxylic acid are reported – [K(H4BPC)(H2O)2]·(H2O) 1 and [K2(H3BPC)(H2O)3]·(H2O) 2 (BPC = benzenepentacarboxylate). In both instances the structures are complex coordination networks, predominantly containing η1 binding modes of the carboxylate and carboxylic acid groups, although bridging (O,O) and (O,O′) carboxylates and μ2‐H2O ligands also feature. Extensive hydrogen bonding is present through the carboxylic acid groups and both coordinated and interstitial water molecules. 相似文献
102.
Suzanne Burling Dr. L. Jonas L. Häller Dr. Elena Mas‐Marzá Dr. Aitor Moreno Stuart A. Macgregor Prof. Mary F. Mahon Dr. Paul S. Pregosin Prof. Dr. Michael K. Whittlesey Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(41):10912-10923
The five‐coordinate ruthenium N‐heterocyclic carbene (NHC) hydrido complexes [Ru(IiPr2Me2)4H][BArF4] ( 1 ; IiPr2Me2=1,3‐diisopropyl‐4,5‐dimethylimidazol‐2‐ylidene; ArF=3,5‐(CF3)2C6H3), [Ru(IEt2Me2)4H][BArF4] ( 2 ; IEt2Me2=1,3‐diethyl‐4,5‐dimethylimidazol‐2‐ylidene) and [Ru(IMe4)4H][BArF4] ( 3 ; IMe4=1,3,4,5‐tetramethylimidazol‐2‐ylidene) have been synthesised following reaction of [Ru(PPh3)3HCl] with 4–8 equivalents of the free carbenes at ambient temperature. Complexes 1 – 3 have been structurally characterised and show square pyramidal geometries with apical hydride ligands. In both dichloromethane or pyridine solution, 1 and 2 display very low frequency hydride signals at about δ ?41. The tetramethyl carbene complex 3 exhibits a similar chemical shift in toluene, but shows a higher frequency signal in acetonitrile arising from the solvent adduct [Ru(IMe4)4(MeCN)H][BArF4], 4 . The reactivity of 1 – 3 towards H2 and N2 depends on the size of the N‐substituent of the NHC ligand. Thus, 1 is unreactive towards both gases, 2 reacts with both H2 and N2 only at low temperature and incompletely, while 3 affords [Ru(IMe4)4(η2‐H2)H][BArF4] ( 7 ) and [Ru(IMe4)4(N2)H][BArF4] ( 8 ) in quantitative yield at room temperature. CO shows no selectivity, reacting with 1 – 3 to give [Ru(NHC)4(CO)H][BArF4] ( 9 – 11 ). Addition of O2 to solutions of 2 and 3 leads to rapid oxidation, from which the RuIII species [Ru(NHC)4(OH)2][BArF4] and the RuIV oxo chlorido complex [Ru(IEt2Me2)4(O)Cl][BArF4] were isolated. DFT calculations reproduce the greater ability of 3 to bind small molecules and show relative binding strengths that follow the trend CO ? O2 > N2 > H2. 相似文献
103.
Dr. Elena Madrid Yuanyang Rong Dr. Mariolino Carta Prof. Neil B. McKeown Richard Malpass‐Evans Prof. Gary A. Attard Tomos J. Clarke Prof. Stuart H. Taylor Prof. Yi‐Tao Long Prof. Frank Marken 《Angewandte Chemie (International ed. in English)》2014,53(40):10751-10754
A highly rigid amine‐based polymer of intrinsic microporosity (PIM), prepared by a polymerization reaction involving the formation of Tröger’s base, is demonstrated to act as an ionic diode with electrolyte‐dependent bistable switchable states. 相似文献
104.
Sarah E. Walker Dr. James A. Jordan‐Hore Dr. David G. Johnson Prof. Dr. Stuart A. Macgregor Dr. Ai‐Lan Lee 《Angewandte Chemie (International ed. in English)》2014,53(50):13876-13879
A direct Pd‐catalyzed C? H functionalization of benzoquinone (BQ) can be controlled to give either mono‐ or disubstituted BQ, including the installation of two different groups in a one‐pot procedure. BQ can now be directly functionalized with aryl, heteroaryl, cycloalkyl, and cycloalkene groups and, moreover, the reaction is conducted in environmentally benign water or acetone as solvents. 相似文献
105.
Specific ion effects on the electrophoretic mobility of small,highly charged peptides: A modeling study 下载免费PDF全文
Stuart A. Allison Hengfu Wu Tuyen M. Bui Lac Dang Giang H. Huynh Tam Nguyen Linda Soegiarto Bi C. Truong 《Journal of separation science》2014,37(17):2403-2410
In this work, we use coarse‐grained modeling to study the free solution electrophoretic mobility of small highly charged peptides (lysine, arginine, and short oligos thereof (up to nonapeptides)) in NaCl and Na2SO4 aqueous solutions at neutral pH and room temperature. The experimental data are taken from the literature. A bead modeling methodology that treats the electrostatics at the level of the nonlinear Poisson Boltzmann equation developed previously in our laboratory is able to account for the mobility of all peptides in NaCl, but not Na2SO4. The peptide mobilities in Na2SO4 can be accounted for by including sulfate binding in the model and this is proposed as one possible explanation for the discrepancy. Oligo arginine peptides bind more sulfate than oligo lysines and sulfate binding increases with the oligo length. 相似文献
106.
Tara E. Tovstiga Elizabeth A. L. Gillis J. Stuart Grossert Robert L. White 《Journal of mass spectrometry : JMS》2014,49(2):168-177
The correlation of anion structure with the fragmentation behavior of deprotonated nitrobenzenesulfonylamino acids was investigated using tandem mass spectrometry, isotopic labeling and computational methods. Four distinct fragmentation pathways resulting from the collision‐induced dissociation (CID) of deprotonated 2‐nitrobenzenesulfonylglycine (NsGly) were characterized. The unusual loss of the aryl nitro substituent as HONO was the lowest energy process. Subsequent successive losses of CO, HCN and SO2 indicated that an ortho cyclization reaction had accompanied loss of HONO. Other pathways involving rearrangement of the ionized sulfonamide group, dual bond cleavage and intramolecular nucleophilic displacement were proposed to account for the formation of phenoxide, arylsulfinate and arylsulfonamide product ions at higher collision energies. The four distinct fragmentation pathways were consistent with precursor–product relationships established by CID experiments, isotopic labeling results and the formation of analogous product ions from 2,4‐dinitrobenzenesulfonylglycine and the Ns derivatives of alanine and 2‐aminoisobutyric acid. The computations confirmed a low barrier for ortho cyclization with loss of HONO and feasible energetics for each reaction step in the four pathways. Computations also indicated that three of the fragmentation pathways started from NsGly ionized at the carboxyl group. Overall, the pathways identified for the fragmentation of the NsGly anion differed from processes reported for anions containing a single functional group, demonstrating the importance of functional group interactions in the fragmentation pathways of multifunctional anions. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
107.
l1-SPIRiT is a fast magnetic resonance imaging (MRI) method which combines parallel imaging (PI) with compressed sensing (CS) by performing a joint l1-norm and l2-norm optimization procedure. The original l1-SPIRiT method uses two-dimensional (2D) Wavelet transform to exploit the intra-coil data redundancies and a joint sparsity model to exploit the inter-coil data redundancies. In this work, we propose to stack all the coil images into a three-dimensional (3D) matrix, and then a novel 3D Walsh transform-based sparsity basis is applied to simultaneously reduce the intra-coil and inter-coil data redundancies. Both the 2D Wavelet transform-based and the proposed 3D Walsh transform-based sparsity bases were investigated in the l1-SPIRiT method. The experimental results show that the proposed 3D Walsh transform-based l1-SPIRiT method outperformed the original l1-SPIRiT in terms of image quality and computational efficiency. 相似文献
108.
Olga Shenderova Suzanne Hens Igor Vlasov Stuart Turner Ying‐Gang Lu Gustaaf Van Tendeloo Amanda Schrand Sergey A. Burikov Tatiana A. Dolenko 《Particle & Particle Systems Characterization》2014,31(5):580-590
The synthesis of a new class of fluorescent carbon nanomaterials, carbon‐dot‐decorated nanodiamonds (CDD‐ND), is reported. These CDD‐NDs are produced by specific acid treatment of detonation soot, forming tiny rounded sp2 carbon species (carbon dots), 1–2 atomic layers thick and 1–2 nm in size, covalently attached to the surface of the detonation diamond nanoparticles. A combination of nanodiamonds bonded with a graphitic phase as a starting material and the application of graphite intercalated acids for oxidation of the graphitic carbon is necessary for the successful production of CDD‐ND. The CDD‐ND photoluminescence (PL) is stable, 20 times more intense than the intrinsic PL of well‐purified NDs and can be tailored by changing the oxidation process parameters. Carbon‐dot‐decorated DNDs are shown to be excellent probes for bioimaging applications and inexpensive additives for PL nanocomposites. 相似文献
109.
This paper treats the plane-strain free-boundary problem describing the equilibrium of a closed cylindrical non-linearly elastic membrane that contains a heavy liquid and a weightless compressible gas and that sits upon a rigid horizontal plane. The material points of the membrane in contact with the rigid plane, the liquid, and the gas are unknowns of the problem. We carefully formulate the geometrically exact equations, and then show that solutions must have attractive regularity, symmetry, and similarity properties, which are not intuitively obvious. There is an interesting interplay between the material behavior and the live pressure loadings generated by gases and heavy liquids. The properties of the equilibrium states depend crucially on the material behaviour of the membrane. In particular, for certain materials the number of equilibrium states changes abruptly as certain parameters describing the liquid and gas change. Thus the system can suffer instabilities of snapping type (with their attendant hysteresis effects), which we term slumping instabilities. 相似文献
110.
Based on the consideration of Boolean dynamics, it has been hypothesized that cell types may correspond to alternative attractors of a gene regulatory network. Recent stochastic Boolean network analysis, however, raised the important question concerning the stability of such attractors. In this paper a detailed numerical analysis is performed within the framework of Langevin dynamics. While the present results confirm that the noise is indeed an important dynamical element, the cell type as represented by attractors can still be a viable hypothesis. It is found that the stability of an attractor depends on the strength of noise related to the distance of the system to the bifurcation point and it can be exponentially stable depending on biological parameters. 相似文献