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991.
Main M Snaith JS Meloni MM Jauregui M Sykes D Faulkner S Kenwright AM 《Chemical communications (Cambridge, England)》2008,(41):5212-5214
The Ugi reaction offers an effective method for preparing chromophore-appended DOTA-monoamide ligands, which can readily be elaborated to their lanthanide complexes. 相似文献
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Money VA Cartmell A Guerreiro CI Ducros VM Fontes CM Gilbert HJ Davies GJ 《Organic & biomolecular chemistry》2008,6(5):851-853
The substrate binding regions of a beta-1,3:1,4 glucanase are revealed through structural analysis with a thio-oligosaccharide and kinetics of enzyme variants. 相似文献
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Korotkikh NI Cowley AH Moore JA Glinyanaya NV Panov IS Rayenko GF Pekhtereva TM Shvaika OP 《Organic & biomolecular chemistry》2008,6(1):195-199
Four stable carbenes, 1-tert-butyl-3,4-diaryl-1,2,4-triazol-5-ylidenes 1a-d, including new fluorine-containing compounds 1c,d, react with a malonic ester to afford heterocyclic zwitterionic compounds 5a-d. The reactions with more acidic compounds (ethyl acetoacetate, malononitrile and 1,3-dimethylbarbituric acid) proceed with substrate deprotonation to form the respective azolium salts 6a-c. The X-ray crystal structure of 5a was also determined. 相似文献
999.
Crystallographic and luminescence studies on salts of the two-coordinate carbene cation, [Au{C(NHCH(3))(NHCH(2)CH(2)OH)}(2)](+), demonstrate the ability of the cation to exist in three different states of aggregation. In colorless, non-luminescent [Au{C(NHCH(3))(NHCH(2)CH(2)OH)}(2)]Cl the cation crystallizes as a monomer with the nearest gold(i) center 6.7890(11) A away. Colorless, luminescent [Au{C(NHCH(3))(NHCH(2)CH(2)OH)}(2)]AsF(6) forms dimers with an AuAu separation of 3.1288(4) A. These dimers form weakly associated extended chains of cations with additional AuAu separations of 3.6625(5) A. [Au{C(NHCH(3))(NHCH(2)CH(2)OH)}(2)]PF(6) is isostructural. Yellow, luminescent [Au{C(NHCH(3))(NHCH(2)CH(2)OH)}(2)](3)(AsF(6))(2)Cl.0.5(H(2)O)(2) and [Au{C(NHCH(3))(NHCH(2)CH(2)OH)}(2)](3)(PF(6))(2)Cl.0.5(H(2)O)(2) form trimers that further aggregate into extended chains with rather short AuAu separations of 3.1301(14) A, 3.1569(14) A and 3.1415(14) A. Absorption, emission and excitation spectra are reported for these salts. The excitation and emission results from the interactions between the gold centers and involves transitions between the filled d(z)((2)) band and the empty p(z) bands with the z axis pointing along the chain of cations. 相似文献
1000.
Spectroscopy, binding to liposomes and production of singlet oxygen by porphyrazines with modularly variable water solubility 总被引:1,自引:0,他引:1
Sholto A Lee S Hoffman BM Barrett AG Ehrenberg B 《Photochemistry and photobiology》2008,84(3):764-773
Three novel classes of porphyrazine-like structures were synthesized to form modular structures in which lipophilicity and water solubility can be tuned. Subtle modification of solubility is an important criterion in selecting a compound for biological photosensitization. The general structure takes the form H2[pz(AnB4-n)], where the core is a porphyrazine (pz) group, A is a pyrrole ring with two sulfide linkages (SR moieties) and B is a pyrrole fused with a 4,7-bis(isopropyloxy)benzo group, with n=4, 3 and 2. These molecules possess their longest wavelength absorption band between 700 and 810 nm, hence laser beams of higher tissue penetration depth could be used to illuminate them in photodynamic therapy (PDT). Armed with absorption bands in the far-red and near-infrared (near-IR), and a capability to tune the solubility, these molecules could make for better sensitizers because of optimized uptake by lipidic membranes and better optical properties. We tested several derivatives of the A4, A3B and A2B2 structures for their singlet oxygen quantum yields in methanol and in liposomes, using 9,10-dimethyl anthracene (DMA) as a singlet oxygen target. Singlet oxygen quantum yields in liposomes ranged from 0.01 to 0.44, with the A2B2 group showing the most promise. In the binding assay to find the equilibrium binding constant, Kb, we detected fluorescence changes due to a change in environment. Peripheral long-chain moieties (the R group in the SR moieties) dominate lipid binding. These moieties range in the hydrophobicity that they induce from C8H17 and benzene, which rendered the molecule totally insoluble in water, to polyethylene glycol (PEG) and carboxylate groups, which imparted water solubility. Each molecule had between 4 and 8 such identical chains. Chains bearing an ether or ester link resulted in measurable equilibrium constants, with a higher Kb for ether substituents. Results for Kb ranged from 0.23 to 26.52 (mg mL(-1))(-1). A delicate balance exists between water solubility and good partitioning to membranes. In general, a higher oxygen-to-carbon ratio in the chains improves binding. Fewer chains and a centrally coordinated zinc ion further improve binding and singlet oxygen production. 相似文献