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131.
Clay A. Henry Mel Judy Barbara Dyer Martin Wagner James L. Matthews 《Photochemistry and photobiology》1995,61(4):410-413
Abstract— The phototoxicity of argon laser irradiation was studied in aqueous suspensions of Porphyromonas endodontalis (American Type Culture Collection [ATCC] 35406), Porphyromonas gingivalis (ATCC 33277), Prevotella denticola (ATCC 33184) and two strains of Prevotella intermedia (ATCC 15033 and 49046), all "black-pigmented bacteria," BPB, that accumulate cellular porphyrins. Several of these species have been implicated in the etiology of Periodontol disease. Non-black-pigmented bacteria were also studied to test the specificity of irradiation as a potential photodynamic treatment for Periodontol infections. Cell suspensions were irradiated with an argon laser at fluences of 20–200 J/cm2 . When cultured in hemin-supplemented media, ATCC 15033 was the most sensitive to irradiation. However, a second strain of the same species (ATCC 49046) was resistant. The photosensitivity of other species ranked ATCC 33277 > 35406 = 33184 = 35496. When hemin was replaced in media by hemoglobin, ATCC 33277 became resistant to irradiation. Protoporphyrin IX content in BPB cells was shown not to be a major factor determining photosensitivity. Oxygen was required during irradiation for BPB species to be affected. Non-black-pigmented bacteria were much less sensitive to irradiation than BPB. 相似文献
132.
David Kessel Kathryn Woodburn† Barbara W. Henderson C. K. Chang 《Photochemistry and photobiology》1995,62(5):875-881
Abstract— Localization and photodynamic efficacy of a monocationic porphyrin (MCP) were assessed using murine leukemia cells in culture. This sensitizer localized at surface membrane loci and catalyzed selective photodamage to membrane structures. Although both cationic and hydrophobic, this porphyrin was not recognized by the multidrug transporter, which excludes many cationic agents from cells that express multidrug resistance. Photodynamic studies with the murine radiation-induced fibrosarcoma tumor model indicated moderate photosensitization of neoplastic lesions in vivo at 3 h, but not at 24 h after sensitizer administration. Pharmacokinetic studies indicate that plasma levels, not tissue levels were the major determinant of photodynamic therapy (PDT) response. Consistent with this observation, vascular damage and disturbances of tissue perfusion followed PDT. These effects were more pronounced in tumor-bearing skin than in normal skin. The therapeutic response to MCP appeared to be related mainly to secondary, probably vascular, effects. 相似文献
133.
PHOTOSENSITIZATION OF MURINE TUMOR, VASCULATURE and SKIN BY 5-AMINOLEVULINIC ACID-INDUCED PORPHYRIN 总被引:2,自引:0,他引:2
Barbara W. Henderson Lurink Vaughan David A. Bellnier Henricus van Leengoed Patricia G. Johnson Allan R. Oseroff 《Photochemistry and photobiology》1995,62(4):780-789
Abstract— The effects of topical and systemic administration of 5-aminolevulinic acid (ALA) were examined in several murine tumor systems with regard to porphyrin accumulation kinetics in tumor, skin and blood, vascular and tumor cell photosensitization and tumor response after light exposure. Marked, transient increases in porphyrin levels were observed in tumor and skin after systemic and topical ALA. Rapid, transient, dose-dependent porphyrin increases were also observed in blood; these were pronounced after systemic ALA injection and mild after topical application. They were highest within 1 h after ALA injection, thereafter declining rapidly. This matched the clearing kinetics of injected exogenous protoporphyrin IX (PpIX). Initially, vascular photosensitivity changed inversely to blood porphyrin levels, increasing gradually up to 5 h post-ALA, as porphyrin was clearing from the bloodstream. This pattern was again matched by injected, exogenous PpIX. After therapeutic tumor treatment vascular disruption of the tumor bed, while observed, was incomplete, especially at the tumor base. Minimal direct tumor cell kill was found at low photodynamic therapy (PDT) doses (250 mg/kg ALA, 135 J/cm2 light). Significant, but limited (<1 log) direct photodynamic tumor cell kill was obtained when the PDT dose was raised to 500 mg/kg systemic ALA, followed 3 h later by 270 J/cm2 , a dose that was however toxic to the animals. The further reduction of clonogenic tumor cells over 24 h following treatment was moderate and probably limited by the incomplete disruption of the vasculature. Tumor responses were highest when light treatment was carried out at the time of highest tumor porphyrin content rather than at the time of highest vascular photosensitivity. Tumor destruction did not reach the tumor base, regardless of treatment conditions. 相似文献
134.
Barbara Pilawa Andrzej B. Wi
ckowski Barbara Trzebicka 《Radiation Physics and Chemistry》1995,45(6):899-908
The multi-component structure of the EPR spectra of Polish medium metamorphosed coal, its macerals and their pyridine extractrion products were analyzed. The bes numerical approximation of the EPR spectra for exinite, vitrinite and their extraction residues was obtained when two Lorentz and one Gauss curve were chosen for calculation. The EPR spectra of inertinite and its residue are superposition of two Lorentz lines. The EPR spectra of the extracts are fitted by single Lorentz lines. Four groups of paramagnetic centres which give the EPR signals with different ranges of linewidths are present in the macerals and the extraction products. Paramagnetic centres with the narrow EPR lines are present not only in inertinites, but also in exinites and vitrinites. Each of the four types of paramagnetic centres is present in macromolecular and molecular part of the macerals. As was expected, four component lines were detected for the EPR spectra of the coal and its residue. Paramagnetic centres responsible for the broad lines are located on structures consisting of a few aromatic rings. Paramagnetic centres of large aromatic structures are responsible for the narrow lines. 相似文献
135.
Laird A. TrimbleMark W. Sumarah Barbara A. BlackwellMark D. Wrona J. David Miller 《Tetrahedron letters》2012,53(8):956-958
Two diastereomeric metabolites (16R) and (16S)-hydroxyroquefortine C were characterized from Penicillium crustosum DAOM 215343. The 16S metabolite is reported for the first time along with evidence for the absolute stereochemistry of both. The metabolites were originally detected by LC-NMR and the structures of the subsequently isolated metabolites were elucidated by HRMS and NMR. 相似文献
136.
Lien Vermeir Arnout Declerck Chak Ming To Barbara Kerkaert Paul Van der Meeren 《Magnetic resonance in chemistry : MRC》2019,57(9):674-685
A time-domain 1H nuclear magnetic resonance relaxometry method was elaborated for the rapid microstructural characterization of mozzarella cheese. For this purpose, there is a strong need to know how the experimentally determined T2 relaxation time distribution can be related to specific constituents in mozzarella. In this study, a detailed investigation is offered for fresh and aged low-moisture mozzarella cheese, often applied as a pizza cheese, by application of both a conventional Carr–Purcell–Meiboom–Gill (CPMG) sequence and a free-induction decay CPMG (FID-CPMG) sequence. The relaxation behavior was further elucidated by addition of deuterium oxide and by mild heat treatment of samples. The relaxation times of water protons in mozzarella were found to range from a few microseconds to some tens of milliseconds (in aged mozzarella) or to about hundred milliseconds (in fresh mozzarella). The upper limit of the T2 distribution can even be extended to the seconds range upon releasing water protons from the mozzarella matrix using a mild heat treatment or upon addition of deuterated water. Both stimuli also provided evidence for the absorption of water into the cheese matrix. The potential release and uptake of water demonstrated that mozzarella acts as a very dynamic system during production and storage. The detected differences in the behavior of the water fraction between fresh and aged low-moisture mozzarella might be utilized to study the influence of either production and/or storage conditions on the cheese ripening process. 相似文献
137.
InIII-Phthalocyanines: Synthesis, Properties, and Crystal Structure of Tetra(n-butyl)ammonium-cis-di(nitrito-O,O')phthalocyaninato(2–)indate(III) [In(Cl)Pc2?] reacts with (nBu4N)NO2 in acetone yielding green-blue (nBu4N)cis[In(NO2)2Pc2?], which crystallizes in the monoclinic space group P21/n (No. 14). Both nitrite anions are coordinated as chelating nitrito-O,O'(NO2) ligands to InIII in cis-geometry. Consequently InIII is octa-coordinated within a distorted “quadratic” antiprism and directed towards the Pc2?-ligand. One of the NO2 ligands has equivalent N? O bonds similar to free nitrite, while the other has asymmetric N? O bonds. Both (In,O,N,O) rings are approximately planar with a dihedral angle of 80°. The Pc2? ligand is distorted in an asymmetrically convex manner. Partially overlapping pairs of Pc2? ligands related by an inversion center form double layers, which are separated by layers containing the (nBu4N)+ cations. The cyclic voltammogram shows three electrode processes, which are assigned to the redox pairs: Pc3?/Pc2? (?0.94 V) < InI/InIII (-0.78 V) < Pc2?/Pc? (0.64 V). The UV-VIS-NIR spectra and vibrational spectra are discussed. 相似文献
138.
139.
Ventura B Barbieri A Degli Esposti A Seneclauze JB Ziessel R 《Inorganic chemistry》2012,51(5):2832-2840
The synthesis, characterization, photophysics, and time-dependent density functional theory (TD-DFT) calculations of spirobifluorene-bipyridine based iridium(III), osmium(II), and mixed Ir/Os complexes are presented. The preparation of the reference and mixed complexes proceeded step-by-step and microwave irradiation facilitated the complexation of osmium. The absorption of the target heterobimetallic derivative, Ir-L-Os, is described by linear combination of half of the absorption spectra of the homobimetallic analogues, Ir-L-Ir and Os-L-Os, due to the occurrence of mixed ligand and metal based transitions when the spirobifluorene-(bpy)(2) bridging ligand L is linked to the metal, confirming a negligible interaction between the substituted metallic chromophores. TD-DFT calculations on monometallic, homo- and hetero-bimetallic complexes fully disentangled the origin of the absorption features. Noticeably, in the mixed Ir-L-Os complex an almost quantitative energy transfer from the (3)Ir to the (3)Os MLCT state is occurring, with a rate constant of 4.1 × 10(8) s(-1) and nearly exclusively via a Dexter-type mechanism mediated by the orbitals of the spiroconjugated ligand. This result, together with the outcomes of the TD-DFT calculations, supports the existence of spiroconjugation and evidences the interesting role of this kind of bridge in the energy transfer dynamics of the arrays. In all the complexes, moreover, the ligand fluorescence is heavily quenched by energy transfer processes toward the metallic appended units; the rate constant is estimated in the order of 10(10) s(-1) for Ir-L-Os and higher than 10(12) s(-1) for the other complexes. In the heterometallic array, both at room temperature and at 77 K, all photons are thus funneled to the emissive Os (3)MLCT state, which acts as energy trap for the antenna cascade. 相似文献
140.
Studies are constantly being conducted on the elaboration of efficient methods to confirm the compatibility of active pharmaceutical ingredients (APIs) and excipients, since medicinal products, apart from their APIs, also contain numerous excipients that not only have important functions in pharmaceutical preparations but can also initiate or participate in interactions with drug substances, which eventually lead to a decline in drug quality. With this in mind, research was undertaken to evaluate two of the most often applied pattern recognition methods, hierarchical cluster analysis (HCA) and principal component analysis (PCA), as supporting techniques in the identification of potential physicochemical interactions that may occur during the preformulation of solid dosage forms. The investigation performed with the use of baclofen and selected excipients has shown that with thermogravimetric analysis, HCA and PCA fulfill their role as supporting techniques in the interpretation of the data obtained. Based on these methods, it is possible to detect incompatibilities between baclofen and excipients, and the data obtained concur strongly with the results of differential scanning calorimetry and IR spectrometry analyses. 相似文献