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71.
Whitehurst CE Yao Z Murphy D Zhang M Taremi S Wojcik L Strizki JM Bracken JD Cheng CC Yang X Shipps GW Ziebell M Nickbarg E 《Combinatorial chemistry & high throughput screening》2012,15(6):473-485
Affinity selection-mass spectrometry (AS-MS) is a sensitive technology for identifying small molecules that bind to target proteins, and assays enabled by AS-MS can be used to delineate relative binding affinities of ligands for proteins. 'Indirect' AS-MS assays employ size-exclusion techniques to separate target-ligand complexes from unbound ligands, and target-associated ligands are then specifically detected by liquid chromatography mass spectrometry. We report how indirect AS-MS binding assays with known reference control compounds were used as guideposts for development of an optimized purification method for CXCR4, a G-protein coupled chemokine receptor, for which we sought novel antagonists. The CXCR4 purification method that was developed was amenable to scale-up and enabled the screening of purified recombinant human CXCR4 against a large combinatorial library of small molecules by high throughput indirect AS-MS. The screen resulted in the discovery of new ligands that competed off binding of reference compounds to CXCR4 in AS-MS binding assays and that antagonized SDF1α-triggered responses and CXCR4-mediated HIV1 viral uptake in cell-based assays. This report provides a methodological paradigm whereby indirect AS-MS-based ligand binding assays may be used to guide optimal integral membrane protein purification methods that enable downstream affinity selection-based applications such as high throughput AS-MS screens. 相似文献
72.
George L Kalume A Esselman B McMahon RJ Reid SA 《The journal of physical chemistry. A》2011,115(35):9820-9827
Halogen atoms are important reactive radicals in the atmosphere. In this work, pulsed jet discharge matrix isolation spectroscopy and computational methods were used to characterize prereactive complexes of halogen atoms with simple halons. Our experiments combined matrix isolation techniques with a pulsed DC discharge nozzle, where a dilute CH(2)XBr (X = H, Cl, Br)/rare gas sample was gently discharged and the products were deposited onto a cold KBr window. The Br···BrCH(2)X (X = H, Cl, Br) complexes were characterized by infrared and electronic spectroscopy, supported by ab initio and density functional theory (DFT) calculations, which shed light on the structure of, bonding in, and binding energy of the complexes. The correlation of charge-transfer energy with donor ionization potential (Mulliken correlation) was examined, and the charge-transfer photochemistry of the complexes was explored. 相似文献
73.
Fireman-Shoresh S Popov I Avnir D Marx S 《Journal of the American Chemical Society》2005,127(8):2650-2655
Enantioselective surfactant-templated thin films were fabricated through the sol-gel (SG) process. The enantioselectivity is general in the sense that it discriminates between pairs of enantiomers not used for the imprinting process. The chiral cationic surfactant (-)-N-dodecyl-N-methylephedrinium bromide (1) was used as the surfactant template, and after its extraction chiral domains were created. The chiral discriminative feature of these films was examined by challenging with pure enantiomer solutions for rebinding. Selective adsorption was shown using (R)- and (S)-propranolol, (R)-2 and (S)-2, respectively, and (R)- and (S)-2,2,2-trifluoro-1-(9-anthryl)ethanol, (R)-3 and (S)-3, respectively, as the chiral probes. The selective adsorption was measured by fluorescence analysis, and the chiral selectivity factors were found to be 1.6 for 2 and 2.25 for 3. In both cases, (R)-enantiomer was adsorbed preferably. The resulting material was characterized by transmission electron microscopy, by diffraction, and by surface area measurements, and was found to be semicrystalline with short-range ordered domains (50 A) of hexagonal symmetry. 相似文献
74.
We report the feasibility of multistage fragmentation in combination with a fast background subtraction method, yielding the equivalent of MS3. The first quadrupole selects an ion of interest, and the ion is axially accelerated into Q2 to generate fragment ions. Subsequent stages of mass selection and fragmentation are obtained by quadrupolar resonant excitation within the Q2 collision cell. The fragments are analyzed downstream by either a resolving quadrupole or a time-of-flight (TOF) mass spectrometer, and multistage spectra are obtained by subtraction (MS(n) - MS(n-1)) for n = 3 or 4. We discuss the characterization of this method, including product ion arrival times, fragmentation efficiencies, and ion selectivity. We report accurate TOF mass spectra of background-subtracted MS3 for protonated molecules reserpine (m/z 609), bosentan (m/z 1552), and taxol (m/z 854). 相似文献
75.
76.
Thomas M. Baker Lisa A. Sloan Lokman H. Choudhury Masahito Murai David J. Procter 《Tetrahedron: Asymmetry》2010,21(9-10):1246-1261
A cascade reaction involving sequential conjugate reduction, stereoselective aldol cyclisation and chemoselective lactone reduction mediated by SmI2–H2O provides access to a cyclopentanol bearing two vicinal quaternary stereocentres with good stereocontrol. The functionalised cyclopentanol product has been converted to a key intermediate in ongoing asymmetric studies towards stolonidiol. 相似文献
77.
Furan-terminated cationic cyclizations allylic alcohols, enones, and N-acyl iminium ions as initiators have been explored as routes to highly functionalized spiro[4,5]decanes, spiro[5,5]undecanes, spiro[4,6]undecanes, and spiro[5,6]dodecanes. 相似文献
78.
Structural investigations of thin films of SiC, SiC with free silicon and various titanium suicides (TiSi2, TiSi and Ti5Si3) are described. The crystal phases have been identified using X-ray diffractometry. The growth of reaction products from surface reactions between silicon and deposited titanium can be observed.Dedicated to Professor Dr. rer.nat. Dr. h.c. Hubertus Nickel on the occasion of his 65th birthday 相似文献
79.
Since the first heavy alkene analogues of germanium and tin were isolated in 1976, followed by West''s disilene in 1981, the chemistry of stable group 14 dimetallenes and dimetallynes has advanced immensely. Recent developments in this field veered the focus from the isolation of novel bonding motifs to mimicking transition metals in their ability to activate small molecules and perform catalysis. The potential of these homonuclear multiply bonded compounds has been demonstrated numerous times in the activation of H2, NH3, CO2 and other small molecules. Hereby, the strong relationship between structure and reactivity warrants close attention towards rational ligand design. This minireview provides an overview on recent developments in regard to bond activation with group 14 dimetallenes and dimetallynes with the perspective of potential catalytic applications of these compounds.This minireview highlights the recent advances in small molecule activation and catalytic applications of homonuclear dimetallenes, dimetallynes and interconnected bismetallylenes of heavier group 14 elements. 相似文献
80.