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71.
Magnetic field decoupling experiments in the optically excited states of NO2 yield decoupling signals with a width of 10 to 40 mG. We attribute these signals to the non-rigidity of the excited molecule. 相似文献
72.
73.
New Copper Complexes Containing Phosphaalkene Ligands. Molecular Structure of [Cu{P(Mes*)C(NMe2)2}2]BF4 (Mes* = 2,4,6‐tBu3C6H2) Reaction of equimolar amounts of the inversely polarized phosphaalkene tBuP=C(NMe2)2 ( 1a ) and copper(I) bromide or copper(I) iodide, respectively, affords complexes [Cu3X3{μ‐P(tBu)C(NMe2)2}3] ( 2 ) (X =Br) and ( 3 ) (X = I) as the formal result of the cyclotrimerization of a 1:1‐adduct. Treatment of 1a with [Cu(L)Cl] (L = PiPr3; SbiPr3) leads to the formation of compounds [CuCl(L){P(tBu)C(NMe2)2}] ( 4a ) (L = PiPr3) and ( 4b ) (L = SbiPr3), respectively. Reaction of [(MeCN)4Cu]BF4 with two equivalents of PhP=C(NMe2)2 ( 1b ) yields complex [Cu{P(Ph)C(NMe2)2}2]BF4 ( 5b ). Similarly, compounds [Cu{P(Aryl)C(NMe2)2}2]BF4 ( 5c (Aryl = Mes and 5d (Aryl = Mes*)) are obtained from ArylP=C(NMe2)2 ( 1c : Aryl = Mes; 1d : Mes*) and [(MeCN)4Cu]BF4 in the presence of SbiPr3. Complexes 2 , 3 , 4a , 4b , and 5b‐5d are characterized by means of elemental analyses and spectroscopy (1H‐, 13C{1H}‐, 31P{1H}‐NMR). The molecular structure of 5d is determined by X‐ray diffraction analysis. 相似文献
74.
K. Huckert R. Rhode O. Roglin R. Weber 《Mathematical Methods of Operations Research》1980,24(1):47-60
Summary A mixed integer multiple criteria model is formulated for scheduling problems. Its solution is obtained by an interactive method based on the Tchebycheff-approximation. For solving greater problems some modifications are discussed at the end of the paper, which are essentially based on the notion of heuristic efficiency.
Zusammenfassung Da bei Ablaufplanungsproblemen häufig mehrere Zielsetzungen zu beachten sind, wird im folgenden Beitrag hierzu ein gemischt-ganzzahliges multikriterielles Entscheidungsmodell formuliert. Seine Lösung erfolgt mit Hilfe eines interaktiven Verfahrens. Zur numerischen Lösung größerer Problemstellungen sind einzelne Verfahrensmodifikationen erforderlich, die im wesentlichen auf dem im letzten Abschnitt eingeführten Begriff der heuristischen Effizienz aufbauen.相似文献
75.
Olaf Heitzsch Karsten Gloe Alfréd Sabela Jiří Koryta Edwin Weber 《Journal of inclusion phenomena and macrocyclic chemistry》1992,13(4):311-319
The complex forming properties with alkali metal and ammonium ions of a series of oligo benzo-condensed 18-crown-6 ethers1–8 having a different gradation of lipophilicity and of molecular rigidity are investigated by voltammetry at the interface of two immiscible electrolyte solutions (ITIES) and by a liquid-liquid extraction technique. The experimental results obtained in the two phase system H2O/nitrobenzene are discussed in relation to the structure of the crown and the cation type. The stability constants for the 1 : 1 complexes of Na+, K+, Rb+, Cs+ and NH
4
+
in nitrobenzene have been determined and compared with the extraction constants for the 1: 1 complexes of Na+ and K+ and for the 1 : 1 and 1 : 2 complexes of Cs+, showing the effect of oligo benzo condensation for the 18-crown-6 system. 相似文献
76.
R. Naumann und Ch. Weber 《Fresenius' Journal of Analytical Chemistry》1971,253(2):111-113
Zusammenfassung Eine Methode zur potentiometrischen Titration von Sulfid mit Natriumplumbat(II)lösung an einer sulfidsensitiven Membranelektrode wird beschrieben. Sie eignet sich zur Bestimmung von 10–4% Sulfid in Gegenwart von Cl–, Br–, J–, SCN–, SO3
2–, S2O3
2–
Wir danken Herrn Dr. K. Obst für wertvolle Hinweise und Diskussionen. 相似文献
Titration of sulphide with a sulphide-ion sensitive electrode
A method is described for the titration of sulphide with sodium plumbate(II) solution using a sulphide-sensitive electrode. The method is suitable for the determination of 10–4% of sulphide in the presence of Cl–, Br–, J–, SCN–, SO3 2–, S2O3 2–.
Wir danken Herrn Dr. K. Obst für wertvolle Hinweise und Diskussionen. 相似文献
77.
In recent years capillary chromatography has gained popularity for trace analyses. Most often UV or electrochemical detection is employed because the small peak volumes make post-column derivatization challenging. We have developed a simple method based on flow injection for determining contributions to peak broadening from post-column reactors. The only requirement for application of our methodology is that diffusion be in the Taylor regime so that radial concentration gradients are relaxed enabling mixing purely by diffusion. 相似文献
78.
Capillaries made of fluorinated ethylene propylene (FEP) with an inner diameter of 50 microm have been employed in capillary zone electrophoresis with UV-Vis absorbance detection. The capillaries were made in the laboratory with a recently developed technique using fluoropolymer heat shrink/melt tubing and a tungsten wire as a template for the channel. An electroosmotic flow was obtained in the channels and it is shown that an FEP capillary is more effective for a cationic test solute than a fused-silica capillary. The compatibility of FEP capillaries with optical detection is evaluated briefly. 相似文献
79.
80.
Wolfgang Oppolzer Roland Achini Emil Pfenninger Hans Peter Weber 《Helvetica chimica acta》1976,59(4):1186-1202
The N-allyl-N-cinnamyl amide 10 undergoes thermal cyclization to a 2:1-mixture of the trans- and cis-benz(f)isoindolines 11a and 12a . By comparison, the thermolysis of the corresponding bis-cinnamylamide 14 proceeds in a highly stereoselective manner to give the cis-fused[4+2]-adduct 16a . Similarly, the trans-fused stereoisomeric adducts 30a and 31a were obtained with high stereochemical control on heating the N-allyl-N-diphenylallyl amide 28 . The thermal transformations 4 → 5 + 6a and 17 → 18a + 20a show the competitive formation of [2+2]-adducts. An alternative approach to (substituted) benz[f]isoindolines 16 via the all-cis-isomer 24a has been developed. The described structures have been assigned on the basis of spectral evidence, chemical correlations and by X-ray-diffraction study of the isomer 16b . These results illustrate the utility of substituent interactions in order to direct intramolecular cyclo-additions at will towards either endo- or exo-products. 相似文献