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961.
M. A. Dzubina G. N. Kuzmina N. N. Lebedenko Yu. V. Korshak O. P. Parenago 《Journal of Thermal Analysis and Calorimetry》1992,38(5):1103-1112
The structure transition temperature, monomer melting point and critical temperatures of polymerization and decomposition of 2,2,6,6-tetramethyl-4-oxy-4-ethynylpiperidin-1-oxyl were determined by means of thermal analysis. Some features of the polymerization of the acetylenic monomer were studied via thermal analysis, and IR and ESR spectroscopy.It was shown that, during non-isothermal temperature increase, the mass loss of the sample associated with the exothermic effect of polymerization occurred at the expense of the monoacetylene sublimation process (42%), a reagent explosion and decomposition of the reaction products formed (15%).
Zusammenfassung Mittels Thermoanalyse wurde die Strukturumwandlungstemperatur, der Monomerschmelzpunkt und die kritischen Temperaturen für Polymerisierung und Zersetzung von 2,2,6,6-Tetramethyl-4-oxy-4-ethynylpiperidin-1-oxyl bestimmt. Mit Hilfe von Thermo-analyse, IR- und ESR-Spektroskopie wurden einige Eigenschaften der Polymerisierung des Acethylen-Monomers untersucht.Es wurde gezeigt, daß bei einem nichtisothermen Temperaturanstieg der Massenverlust der Probe zunimmt, verbunden mit einem exothermen Effekt der eingetretenen Polymerisierung auf Kosten des Monoacetylen-Sublimierungsprozesses [42%], der Explosion und der Zersetzung der gebildeten Reaktionsprodukte [15%].相似文献
962.
963.
CHEN Li-Juan MENG Ze-Rong ZHANG Quan-Zheng WU Xiao-Yuan LU Can-Zhong② 《结构化学》2006,25(10):1189-1192
1 INTRODUCTION Much interest has been focused on the design and syntheses of supramolecular coordination polymers with novel topologies and structural motifs because of their encouraging potential applications in the fields of nonlinear optics, catalysis and separation, magnetism and molecular recognition[1, 2]. In princi- ple, control over the type and topology of the coor- dination polymers can be achieved by careful choice of ligand, metal coordination geometry preference, inorganic cou… 相似文献
964.
A palladium-catalysed four-component process is described involving carbon monoxide, allene and aryl/heteroaryl iodides generating (π-allyl) palladium species, which are intercepted by alkene tethered nitrogen nucleophiles to afford 1,6- and 1,7-dienones. Subsequent ring closing metathesis affords five- and six-membered N-heterocyclic enones. The N-heterocyclic enones are active dipolarophiles in 1,3-dipolar cycloaddition reactions as exemplified by azomethine ylide and nitrone cycloadditions. 相似文献
965.
二溴羟基苯基荧光酮—乳化剂OP荧光熄灭法测定微量铬(Ⅵ) 总被引:11,自引:3,他引:11
本文基于Cr(Ⅵ)-二溴羟基苯基荧光酮(DBH-PF)-OP体系的荧光熄灭效应,提出一种测定痕量铬(Ⅵ)的新荧光方法。在pH2.4-4.1的HCl-NaAc缓冲介质和OP存在下,Cr(Ⅵ)与DBH-PF形成1:2的橙红色络合物,络合物的最大激发发工和发射波长分别是365mm和528nm。铬(Ⅵ)量在0.05-1.5μg/25ml范围内与△F呈线性关系,检测限是2.0ng/ml。方法用于电镀废液,废 相似文献
966.
Summary Steroid ketoximes were reduced with sodium tetrahydroborate in the presence of nickel chloride or molybdenum trioxide. These processes yielded 17- and 20-aminosteroids (1c–5c) in higher yields than common reduction methods.
Steroide, 53. Mitt.: Neue Wege zu Aminosteroiden
Zusammenfassung Oxime von Ketosteroiden wurden mit NaBH4 in Gegenwart von NiCl2 und MoO3 reduziert. Dieses Verfahren lieferte 17- und 20-Aminosteroide(1c–5c) in größeren Ausbeuten als übliche Methoden.相似文献
967.
The reaction process of the thermal dehydration of dilithium tetraborate trihydrate, Li2B4O73H2O, was reinvestigated from a viewpoint of reaction kinetics. On the basis of the results of thermogravimetry, constant rate thermal analysis, powder X-ray diffractometry, infrared spectroscopy and scanning electron microscopy, it was confirmed that the reaction proceeds via three consecutive kinetic steps characterized by different activation energies. The first and second kinetic steps, accompanied by the destruction of the original crystal structure of the reactant, seem to be assigned to the surface and internal reactions, respectively. During the third kinetic step, the thermal dehydration of hydrated amorphous intermediate, produced at the second kinetic step, and crystallization of the final dehydration product, Li2B4O7, are likely to take place concurrently.This revised version was published online in November 2005 with corrections to the Cover Date. 相似文献
968.
V. Ramamoorthy A. Ramasubbu S. Muthusubramanian S. Sivasubramanian 《Journal of inclusion phenomena and macrocyclic chemistry》1999,33(1):69-80
The nitrone is found to be included in the -cyclodextrin cavity in two different stoichiometries viz., 1G : 1H and 1G : 2H – the existence of which is proved by physical methods. The 1G : 2H complex of the nitrone serves as a good potent dipolarophile in the 1,3-dipolar cycloaddition reactions with olefins resulting in rate acceleration and regioselection. 相似文献
969.
Roman Mazurkiewicz 《Monatshefte für Chemie / Chemical Monthly》1989,120(11):973-980
Summary N-Acylanthranilamides react with dibromotriphenylphosphorane in the presence of triethylamine as HBr captor to give 4-imino-4H-3,1-benzoxazines in good yields. If the reaction is carried out without acid acceptor, N-acetylanthranilamides yield 2-methyl-4-quinazolones, whereas N-benzoylanthranilamides give 2-phenyl-4-imino-4H-3,1-benzoxazines. It has also been found that 2-methyl-4-imino-4H-3,1-benzoxazines rearrange under the influence of HCl or HBr into the respective 2-methyl-4-quinazolones; 2-phenyl-4-imino-4H-3,1-benzoxazines, however, do not undergo such a rearrangement.
Synthese und Umlagerung von 4-Imino-4H-3,1-benzoxazinen
Zusammenfassung Die Umsetzung von N-Acyl-anthranilsäure-amiden mit Triphenyldibromphosphoran in Gegenwart von Triethylamin als HBr-Akzeptor führt mit guten Ausbeuten zu 4-Imino-4H-3,1-benzoxazinen. Wird die Reaktion ohne säurebindendes Mittel durchgeführt, dann entstehen aus N-Acetyl-anthranilsäure-amiden 2-Methylchinazolone-4, jedoch erhält man aus N-Benzoylanthranilsäure-amiden 2-Phenyl-4-imino-4H-3,1-benzoxazine. 2-Methyl-4-imino-4H-3,1-benzoxazine erleiden unter dem Einfluß von HBr oder HCl eine Umlagerung in entsprechende 2-Methylchinazolone-4, während 2-Phenyl-4-imino-4H-3,1-benzoxazine zu einer solchen Umlagerung nicht befähigt sind.相似文献
970.
G. G. Wang J. M. Wang W. Q. Mao H. B. Shao J. Q. Zhang C. N. Cao 《Journal of Solid State Electrochemistry》2005,9(7):524-530
LiMn2O4 powder for lithium-ion batteries was prepared by a precipitation method, and the effects of calcination temperature on the physical properties and electrochemical performance of the samples were investigated by various methods. The results of X-ray diffraction (XRD) showed that the lattice parameter (a) and the unit cell volume (v) decrease with the increasing calcination temperature, and the LiMn2O4 sample calcined at 750°C has smaller particle size and higher crystallinity than other samples. The results of the electrochemical experiments showed that the sample calcined at 750°C has larger peak currents, higher initial capacity, and better cycling capability, because of its lower charge-transfer resistance and larger diffusion coefficient of Li+ ions than those of other samples. 相似文献