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排序方式: 共有361条查询结果,搜索用时 625 毫秒
91.
Nicola M. Boyle Jonathan Rochford Mary T. Pryce 《Coordination chemistry reviews》2010,254(1-2):77-102
This review focuses on the synthesis, photophysical and electrochemical properties of thienyl porphyrins where processes such as electron transfer, energy transfer and electropolymerisation are discussed. The purpose of this review is to examine the influence of the thienyl ring, whether it be directly connected (via meso and β positions) or indirectly connected (via a covalent linker or axial coordination) on the ground and excited state electronic properties of the porphyrin macrocycle. Additionally, the importance of the electronic properties of a bridging oligothiophene between the porphyrin and another centre in supramolecular systems is discussed. Also included are applications of thienyl porphyrins in such areas as catalysis, therapeutics, (opto)electronics and electron-transfer/light-harvesting systems. 相似文献
92.
Boyle NM Coleman AC Long C Ronayne KL Browne WR Feringa BL Pryce MT 《Inorganic chemistry》2010,49(22):10214-10216
Time-resolved infrared spectroscopy was used to probe the photochemistry of three (μ(2)-alkyne)Co(2)(CO)(6) complexes. The data indicate the formation of a triplet diradical species, with lifetimes in the range 38-71 ps. Theoretical calculations support these experimental findings. No evidence for the CO loss species, (μ(2)-alkyne)Co(2)(CO)(5), was observed, and this is rationalized by the low quantum yield for this process at the excitation wavelengths used. 相似文献
93.
Grant A. Boyle Thavendran Govender Hendrik G. Kruger Glenn E. M. Maguire 《Structural chemistry》2009,20(5):925-932
The complete NMR elucidation of five camphor-derived ligands is reported. 2D NMR techniques such as NOESY are used to assist
in the determination of the orientation of the donor groups in space. The compounds were synthesized as ligands to be used
in asymmetric catalysis. They represent the first instance where both donor groups are pendant on the C3 position of the camphor
skeleton. The single crystal X-ray structure of one of the ligands was obtained and was helpful in determining the potential
NOESY interactions within the molecule. For the other ligands, density functional theory (DFT) optimizations was performed
[B3LYP/6-31+g(d)] to visualize possible NOE interactions.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
94.
Malatesti N Hudson R Smith K Savoie H Rix K Welham K Boyle RW 《Photochemistry and photobiology》2006,82(3):746-749
Two boron complexes of 5-phenyldipyrromethenes bearing isothiocyanate groups on the phenyl ring have been synthesized for the first time. The utility of these new fluorescence probes for labeling biologically relevant proteins is demonstrated on two monoclonal antibodies that bind to antigens overexpressed on cancer cells. Spectral comparison of the two structures reveals significant photophysical differences, including bathochromically shifted excitation and emission bands, increased molar absorptivity and a large increase in fluorescence quantum yield of approximately 10 times. Differences in photophysical parameters are linked to hindered rotation of the phenyl ring in one of the probes. 相似文献
95.
Goj LA Blue ED Delp SA Gunnoe TB Cundari TR Pierpont AW Petersen JL Boyle PD 《Inorganic chemistry》2006,45(22):9032-9045
Monomeric copper(I) alkyl complexes that possess the N-heterocyclic carbene (NHC) ligands IPr, SIPr, and IMes [IPr = 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene, SIPr = 1,3-bis(2,6-diisopropylphenyl)imidazolin-2-ylidene, IMes = 1,3-bis(2,4,6-trimethylphenyl)imidazol-2-ylidene] react with amines or alcohols to release alkane and form the corresponding monomeric copper(I) amido, alkoxide, or aryloxide complexes. Thermal decomposition reactions of (NHC)Cu(I) methyl complexes at temperatures between 100 and 130 degrees C produce methane, ethane, and ethylene. The reactions of (NHC)Cu(NHPh) complexes with bromoethane reveal increasing nucleophilic reactivity at the anilido ligand in the order (SIPr)Cu(NHPh) < (IPr)Cu(NHPh) < (IMes)Cu(NHPh) < (dtbpe)Cu(NHPh) [dtbpe = 1,2-bis(di-tert-butylphosphino)ethane]. DFT calculations suggest that the HOMO for the series of Cu anilido complexes is localized primarily on the amido nitrogen with some ppi(anilido)-dpi(Cu) pi-character. [(IPr)Cu(mu-H)]2 and (IPr)Cu(Ph) react with aniline to quantitatively produce (IPr)Cu(NHPh)/dihydrogen and (IPr)Cu(NHPh)/benzene, respectively. Analysis of the DFT calculations reveals that the conversion of [(IPr)Cu(mu-H)]2 and aniline to (IPr)Cu(NHPh) and dihydrogen is favorable with DeltaH approximately -7 kcal/mol and DeltaG approximately -9 kcal/mol. 相似文献
96.
Gerung H Boyle TJ Tribby LJ Bunge SD Brinker CJ Han SM 《Journal of the American Chemical Society》2006,128(15):5244-5250
A simple solution synthesis of germanium (Ge0) nanowires under mild conditions (<400 degrees C and 1 atm) was demonstrated using germanium 2,6-dibutylphenoxide, Ge(DBP)2 (1), as the precursor where DBP = 2,6-OC6H3(C(CH3)3)2. Compound 1, synthesized from Ge(NR2)2 where R = SiMe3 and 2 equiv of DBP-H, was characterized as a mononuclear species by single-crystal X-ray diffraction. Dissolution of 1 in oleylamine, followed by rapid injection into a 1-octadecene solution heated to 300 degrees C under an atmosphere of Ar, led to the formation of Ge0 nanowires. The Ge0 nanowires were characterized by transmission electron microscopy (TEM), X-ray diffraction analysis, and Fourier transform infrared spectroscopy. These characterizations revealed that the nanowires are single crystalline in the cubic phase and coated with oleylamine surfactant. We also observed that the nanowire length (0.1-10 microm) increases with increasing temperature (285-315 degrees C) and time (5-60 min). Two growth mechanisms are proposed based on the TEM images intermittently taken during the growth process as a function of time: (1) self-seeding mechanism where one of two overlapping nanowires serves as a seed, while the other continues to grow as a wire; and (2) self-assembly mechanism where an aggregate of small rods (<50 nm in diameter) recrystallizes on the tip of a longer wire, extending its length. 相似文献
97.
The silyl palladium complexes (dcpe)PdH(SiHtBu2) and (dcpe)Pd(SiHMe2)2 display NMR spectra that vary with temperature. The dynamic NMR behavior is consistent with long-lived sigma-complexes as intermediates. In the case of (dcpe)PdH(SiHtBu2), the intermediate is believed to be a symmetric complex with doubly bridged hydrogen atoms between the silicon and palladium. Dynamic interchange of the two silicon atoms in (dcpe)Pd(SiHMe2)2 is consistent with an intermediate Si-Si sigma-complex. 相似文献
98.
We classify certain sofic shifts (the irreducible Point Extension Type, or PET, sofic shifts) up to flow equivalence, using invariants of the canonical Fischer cover. There are two main ingredients.
相似文献
- (1)An extension theorem, for extending flow equivalences of subshifts to flow equivalent irreducible shifts of finite type which contain them.
- (2)The classification of certain constant to one maps from SFTs via algebraic invariants of associated G-SFTs.
99.
Fluorescent pyrid-2-yl ureas were prepared by treating halogenated 2-aminopyridines with hexyl isocyanate, followed by Sonogashira coupling with arylacetylenes. The sensors emit light of ~360 nm with quantum yields of 0.05-0.1 in acetonitrile solution. Addition of strong organic acids (pK(a) < 13 in CH(3)CN) shifts the fluorescence band to lower energy, and clean isoemissive behavior is observed. Fluorescence response curves (i.e., F/F(0) vs [acid](total)) are hyperbolic in shape for CCl(3)COOH and CF(3)COOH, with association constants on the order of 10(3) M(-1) for both acids. (1)H NMR titrations and DFT analyses indicate that trihaloacetic acids bind in ionized form to the receptors. Pyridine protonation disrupts an intramolecular H-bond, thereby unfolding an array of ureido NH donors for recognition of the corresponding carboxylates. Methanesulfonic acid protonates the sensors, but no evidence for conjugate base binding at the urea moiety is found by NMR. An isosteric control compound that lacks an integrated pyridine does not undergo significant fluorescence changes upon acidification. 相似文献
100.
ER Badman GE Patterson JM Wells RE Santini RG Cooks 《Journal of mass spectrometry : JMS》1999,34(8):889-894
Dual-detector differential non-destructive Fourier transform detection in a quadrupole ion trap is shown to improve signal intensity and reduce noise compared with spectra recorded using a single detector. A larger area detector in each end-cap electrode is machined to fit its hyperbolic shape and so minimize field imperfections on the z-axis. Argon, acetophenone and bromobenzene spectra were recorded to allow a comparison between single- and dual-detector (differential) modes of detection and to demonstrate the improvement achieved with differential detection. Copyright 1999 John Wiley & Sons, Ltd. 相似文献