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51.
H. Meier E. Zimmerhackl W. Albrecht D. ßösche W. Hecker P. Menge A. Ruckdeschel E. Unger G. Zeitler 《Mikrochimica acta》1970,58(4):733-743
Zusammenfassung Die hochspannungselektrophoretische Wanderung der Halogenokomplexe der Platinmetalle und weiterer anorganischer Ionen wird bei Anwendung von Polycarbonsäuren (Oxalsäure, Bernsteinsäure, Apfelsäure, Weinsäure und Zitronensäure) als Elektrolyt untersucht und der Einfluß des pH-Werts und der Konzentration der Substanzen auf die Wanderung geprüft. Es wird festgestellt, daß die auf die abgestufte Komplexbildungstendenz der Polycarbonsäuren (Zitronensäure > Weinsäure Apfelsäure > Bernsteinsäure) rückführbaren Unterschiede der Wanderungsgeschwindigkeiten für die Trennung anorganischer Gemische gut einzusetzen sind. Für die Chlorokomplexe der Platinmetalle wird eine Abstufung der Beweglichkeiten in der Reihe Ir Pt Os > Rh > > Pd > Ru (> Rh) gefunden.
The high voltage electrophoretic separation of inorganic ions with special consideration of the platinum metals
Summary The high voltage eleetrophoretic migration of the halogen complexes of the platinum metals and other inorganic ions was studied with the employment of the polycarboxylic acids (oxalic, succinic, malic, tartaric, citric) as electrolyte, and the influence of the pH-value and the concentration of the substances on the migration investigated. It was found that the differences in the migration velocities, which may be traced back to the graded complex-forming tendency of the polycarboxylic acids (citric > tartaric malic > > succininic) can be used to good advantage in the separation of inorganic mixtures. With respect to the chlorocomplexes of the platinum metals, a decrease in the mobilities was discovered in the series Ir > Pt > Os > > Rh > Pd > Ru (>Rd).相似文献
52.
H. Meier E. Zimmerhackl W. Albrecht D. Bösche W. Hecker P. Menge A. Ruckdeschel E. Unger G. Zeitler 《Mikrochimica acta》1970,58(3):553-563
Zusammenfassung Die hochspannungselektrophoretische Wanderung der Halogenokomplexe der Platinmetalle und einer Reihe weiterer anorganischer Ionen wird mit Nitrilotriessigsäure und Äthylendiamintetraessigsäure als Elektrolyt in Abhängigkeit von verschiedenen Versuchsparametern (Elektrolytkonzentration,ph-Wert und Substanzmenge) untersucht. Die Wanderungsgeschwindigkeiten der verschiedenen Metallionen bzw.-komplexe zeigen charakteristische Abstufungen, die sich mit den für die hochspannungselektrophoretische Wanderung gültigen Gesetzmäßigkeiten erklären lassen. Beispielsweise beobachtet man eine Abnahme der Beweglichkeit bei Ersatz von Chlorid- durch Bromidionen (Masseneinfluß), Auswirkungen der vomph bzw. der Elektrolytkonzentration abhängigen unterschiedlichen Komplexierungen zwei- und dreiwertiger Ionen, Einflüsse der auf Hydrolyse zurückgehenden Änderungen der Ligandenzusammensetzung sowie Unterschiede der Wanderungsgeschwindigkeiten als Folge der Komplexierung mit NTE oder AeDTE.Durch die unter bestimmten Bedingungen erreichbare Abstufung der Beweglichkeiten können verschiedene Gemische, unter anderem auch die Chlorokomplexe der meisten Platinmetalle in der Reihenfolge Ir > Os Pt > Rh Pd > Ru (> Rh), getrennt werden. NTE ist dabei für Trennungen besser als AeDTE geeignet.
The high tension electrophoretic separation of inorganic ions with special reference to the platinum metals. I
Summary The high tension electrophoretic migration of the halogeno complexes of the platinum metals and several other inorganic ions was investigated with nitrilotriacetic acid and ethylenediaminetetraacetic acid as electrolytes in relation to the various experimental parameters (electrolyte concentration,ph-value, and amount of substance). The migration velocities of the various metal ions or complexes exhibit characteristic gradations that may be explained on the basis of the regularities that are valid for the high tension electrophoretic migration. Instances are: a decrease was observed in the mobility when chloride was replaced by bromide ions (mass effect), influence of different complexing of di- and trivalent ions that are related to changes in theph or electrolyte concentration, or influences of the changes due to hydrolysis in the composition of the ligands or alterations in the migration rates resulting from complexing with nitrolotriacetic acid or EDTA.The gradation of the mobility obtained under certain conditions are employed as the basis of a procedure for separating various mixtures, including also the chloro complexes of most of the platinum metals in the succession Ir > Os Pt > Rh Pd > Ru (> Rh). It has been found that NTE is better for separations than EDTA.相似文献
53.
It is shown that azulenium cations in the first electronically excited state S1 are stronger acids than in the ground state S0. Their apparent pK″*, obtained from the H0-dependence of the quenching of the azulenium cation S1 → S0 fluorescence does not correspond to a true acid-base equilibrium in the electronically excited state S1. The pK″* values are kinetically controlled, the rate of reprotonation of azulene in the S1 state being too low to compete with the internal conversion to S0. 相似文献
54.
Wyss HM Innerlohinger J Meier LP Gauckler LJ Glatter O 《Journal of colloid and interface science》2004,271(2):388-399
The aggregation of concentrated aqueous silica suspensions is characterized by means of static light scattering. We use an in situ destabilization mechanism based on the enzyme-catalyzed hydrolysis of urea. This method enables us to continuously and homogeneously change the interparticle potential from repulsive to attractive without disturbing the aggregation process. Moreover, our electrostatically stabilized suspensions can be destabilized by two different methods. In the first method, the pH is shifted toward the isoelectric point of the particles ( Delta pH method), thereby leading to a decrease of their surface charge. In the second method, the ionic strength is continuously increased at constant pH ( Delta I method), leading to a compression of the electrical double layer around the charged particles. A laboratory-built flat-cell light-scattering instrument is used, which allows fast data acquisition and an adjustment of the sample cell thickness. To circumvent multiple scattering effects, we use a very small sample thickness ( approximately 13 microm). In addition, the refractive index difference between the aqueous phase and the particles is reduced by adding sucrose to the liquid phase of our suspensions. We are able to characterize the structural changes at the very early stages of the destabilization process, where no significant effects are yet detected in macroscopic rheological measurements. While during the Delta pH destabilization, the scattering curve shows significant changes only after some characteristic delay time, it changes continuously during the Delta I destabilization. The latter is attributed to the formation of a weak pre-gel structure in the suspensions, as a shallow secondary minimum appears in the interparticle potential. Data are evaluated by using a HMSA square-well structure factor model. Results are in good agreement with those predicted from DLVO theory. 相似文献
55.
Synthesis of β-D -Glucopyranosides of some Hydroxylated Vitamin-D Compounds Cholesta-5, 7-diene-1α, 3β-diol (1a) was glycosylated with ‘α-acetobromoglucose’ (2) as well as with ‘α-acetobromocellobiose’ (4) to yield the 3-(glycosides) 1b and 1c , respectively. Irradiation of these products with UV light followed by thermal isomerization led to the corresponding vitamin-D derivatives 3a and 3c. Direct glucosylation of vitamin D3 (3f) and vitamin D2 (5a) with 2 gave the derivatives 3g and 5b , respectively. With 25-hydroxycholecalciferol ( = calcidiol; 6a ) as substrate, besides the 3-(glucoside) 6b small amounts of the C(25)-analog 6c were formed. The reaction of 1α, 25-dihydroxycholecalciferol ( = calcitriol; 6e ) with 2 furnished the 3- and the 1-(glucoside) ( 6f and 6g , respectively) as the major components and the C(25)-analog 6h in minor quantity. From the acetylated 3-(glucosides) 3a, 3g, 5b, 6b , and 6f , the free glucopyranosides 3b, 3h, 5c, 6d , and 6i , respectively, were prepared as well as the free glucopy-ranosyl-glucopyranoside 3d from the acetylated disaccharide 3c. 相似文献
56.
HoClTe2O5: A Telluriumdioxide‐rich Holmium(III) Chloride Oxotellurate(IV) While attempting to synthesize anionically derivatized holmium oxotellurates by reacting holmium chloride (HoCl3) with tellurium oxide (TeO3; molar ratio 1 : 3, 800°C 10 d) in evacuated silica ampoules, transparent, greenish yellow and coarse single crystals of holmium(III) chloride oxotellurate(IV) HoClTe2O5 (triclinic, P1; a = 762.07(6), b = 796.79(6), c = 1010.36(8) pm, α = 100.987(4), ß = 99.358(4), γ = 91.719(4)°; Z = 4) were obtained. The crystal structure contains eightfold coordinated (Ho1)3+ (only surrounded by oxygen atoms) and sevenfold coordinated (Ho2)3+ cations (surrounded by one chloride and six oxide anions). Each sort of holmium polyhedra convenes independently to chains along [100] by edge‐sharing which again combine alternately via O6 and O9 to form 2{[Ho2O10(Cl1)]15—} layers parallel (001). Each of the four crystallographically different Te4+ cations are surrounded by three close oxygen atoms (d(Te—O) = 188 — 195 pm) and always one more situated further away. The stereochemical activity of the non‐bonding electron pairs (“lone pairs”) leads to ψ1‐trigonal bipyramidal coordination figures. The ψ1‐tetrahedral [TeO3]2— basic units form discrete [Te2O5]2— doubles with ecliptic conformation which are arranged in a fish‐bone pattern parallel to (001) on both sides of the 2{[Ho2O10Cl]15—} layers. The coherence of the 2{[Ho2(Cl1)Te4O10]+} layers is exclusively maintained via Cl2—Te1 contacts with an extraordinary long distance of 335 pm. As (Cl1)— belongs to the coordination sphere of (Ho2)3+ and (Cl2)— is only surrounded by Te4+, the compound should be correctly named holmium(III) chloride oxochlorotellurate(IV) Ho2Cl[Te4O10Cl] (Z = 2). 相似文献
57.
Self-assembly of amphiphilic hexapyridinium cations at the air/water interface and on HOPG surfaces.
Haofei Gong Dr. Björn Bredenkötter Dr. Christoph Meier Carola Hoffmann‐ Richter Dr. Ulrich Ziener Dr. Dirk G. Kurth Dr. Dirk Volkmer Prof. Dr. 《Chemphyschem》2007,8(16):2354-2362
Mono- and multilayers of a novel amphiphilic hexapyridinium cation with six eicosyl chains (3) are spread at the air/water interface as well as on highly ordered pyrolytic graphite (HOPG). On water, the monolayer of 3 is investigated by recording surface pressure/area and surface potential/area isotherms, and by Brewster angle microscopy (BAM). Self-organized tubular micelles with an internal edge-on orientation of molecules form at the air/water interface at low surface pressure whereas multilayers are present at high surface pressure, after a phase transition. Packing motifs suggesting a tubular arrangement of the constituting molecules were gleaned from atomic force microscopy (AFM) investigations of Langmuir-Blodgett (LB) monolayers being transferred on HOPG at different surface pressures. These LB film structures are compared to the self-assembled monolayer (SAM) of 3 formed via adsorption from a supersaturated solution, which is studied by scanning tunnelling microscopy (STM). On HOPG the SAM of 3 consists of nanorods with a highly ordered edge-on packing of the aromatic rings and an arrangement of alkyl chains which resembles the packing of molecules at the air/water interface at low surface pressure. Additional details of the molecular packing were gleaned from single-crystal X-ray structure analysis of the hexapyridinium model compound 2b, which possesses methyl instead of eicosyl residues. 相似文献
58.
Braulio Insuasty M
Nica Ramos Jairo Quiroga Adolfo Sanchez Manuel Nogueras Norbert Hanold Herbert Meier 《Journal of heterocyclic chemistry》1994,31(1):61-64
The reaction of 4,5-diamino-1,6-dihydropyrimidin-6-ones 1 with one equivalent of the chalcones 2 leads in an acidic medium to the formation of the 2,4-diaryl-2,3,6,7-tetrahydro-1H-pyrimido[4,5-b][1,4]diazepin-6-ones 3a-m . The structure elucidation of the products is based on detailed nmr investigations including selective 13C[1H] decoupling experiments. 相似文献
59.
Potential photosensitizers for photodynamic therapy. III. Photophysical properties of a lipophilic chlorin and its zinc and tin chelates. 总被引:1,自引:0,他引:1
C Grewer G Schermann R Schmidt A V?lcker H D Brauer A Meier F P Montforts 《Journal of photochemistry and photobiology. B, Biology》1991,11(3-4):285-293
Photophysical properties of a lipophilic chlorin derivative and its zinc and tin chelates were investigated in chloroform. The quantum yields of the fluorescence phi F, of the S1----T1 intersystem crossing phi T and of singlet oxygen (1 delta g) formation phi delta, as well as the Stern-Volmer constants for the quenching of the S1 states by oxygen and the rate constants of quenching of O2(1 delta g) by the chlorins were measured. In comparison to the metal-free chlorin an increase of phi T and a decrease of phi F have been observed for the metal-containing derivatives, whereas the phi delta values remain constant. 相似文献
60.
Tahir Altunbulduk Heinz Meier K?cker Wolfgang Frenzel 《Fresenius' Journal of Analytical Chemistry》1995,351(7):593-598
Detailed investigations have been reported on the application of a common procedure using bromate in nitric acid for the removal of the interference of sulfide in the direct potentiometric determination of chloride using silver-based ion selective electrodes in a flow injection system. It is shown that this procedure is not very efficient and carries a high risk of chloride underestimation. With increasing levels of sulfide the oxidation of chloride to elemental chlorine becomes progressively significant and under certain circumstances virtually no chloride is left irrespective of its initial concentration. Hydrogen peroxide in alkaline medium is proposed as a suitable alternative for the efficient removal of sulfide without any adverse effects on the potentiometric method. 相似文献