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971.
Vanadium‐Controlled Crystallization of Stereoisomers of NBu4[VO2(N‐Salicylidene‐isoleucinato)] through Epimerization
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Lukáš Krivosudský Prof. Peter Schwendt Dr. Ján Šimunek Dr. Róbert Gyepes 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(29):8872-8875
Reported herein is a simple synthetic and crystallization procedure for sequential isolation of two stereoisomers of isoleucine‐derived vanadium(V) complexes from a racemic mixture with three stereogenic centers and therefore eight hypothetical species. The products of this crystallization were characterized by electronic and vibrational circular dichroism, NMR spectroscopy, and polarimetry to compare the chiroptic properties of the enantiomerically pure analogues prepared from L ‐isoleucine and D ‐allo‐isoleucine. NMR studies pointed to the yet unobserved phenomenon of vanadium‐catalyzed epimerization of isoleucine. 相似文献
972.
Dr. Elizabeth Castillo‐Martínez Dr. Javier Carretero‐González Prof. Michel Armand 《Angewandte Chemie (International ed. in English)》2014,53(21):5341-5345
The redox entity comprising two Schiff base groups attached to a phenyl ring (? N?CH? Ar? HC?N? ) is reported to be active for sodium‐ion storage (Ar=aromatic group). Electroactive polymeric Schiff bases were produced by reaction between non‐conjugated aliphatic or conjugated aromatic diamine block with terephthalaldehyde unit. Crystalline polymeric Schiff bases are able to electrochemically store more than one sodium atom per azomethine group at potentials between 0 and 1.5 V versus Na+/Na. The redox potential can be tuned through conjugation of the polymeric chain and by electron injection from donor substituents in the aromatic rings. Reversible capacities of up to 350 mA h g?1 are achieved when the carbon mixture is optimized with Ketjen Black. Interestingly, the “reverse” configuration (? CH?N? Ar? N?HC? ) is not electrochemically active, though isoelectronic. 相似文献
973.
《Arabian Journal of Chemistry》2014,7(2):219-226
A series of 1-methyl-N-[(substituted-phenylmethylidene)-1H-benzimidazol-2-amines (4a–4g) were prepared via the formation of 1-methyl-1H-benzimidazol-2-amine (3), which was prepared by the cycloaddition of o-phenylenediamine (1) with cyanogen bromide in the presence of aqueous base followed by N-methylation with methyl iodide in the presence of anhydrous potassium carbonate in dry acetonitrile. Moreover, the four-membered β-lactam ring was introduced by the cycloaddition of 4a–4g and chloroacetyl chloride in the presence of triethylamine catalyst to give 3-chloro-1-(1-methyl-1H-benzimidazol-2-yl)-(4′-substituted)-phenylazetidin-2-one 5a–5g. A total of 14 compounds were synthesized and characterized by IR, 1H NMR, 13C NMR and Mass spectral technique, in addition they were evaluated for anti-bacterial and cytotoxic properties. Among the chemicals tested 4a, 4b, 5a, 5b, 5g exhibited good antibacterial activity and 5f, 5g shown good cytotoxic activity in vitro. 相似文献
974.
Bilender P. Allahverdiev 《Mathematical Methods in the Applied Sciences》2015,38(7):1273-1281
It is shown in the limit‐circle case that system of root functions of the non‐self‐adjoint maximal dissipative (accumulative) Bessel operator and its perturbation Sturm–Liouville operator form a complete system in the Hilbert space. Furthermore, asymptotic behavior of the eigenvalues of the maximal dissipative (accumulative) Bessel operators is investigated, and it is proved that system of root functions form a basis (Riesz and Bari bases) in the same Hilbert space. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
975.
呼和满都拉 《原子与分子物理学报》2015,32(1):7-14
本文采用密度泛函理论中的M05方法对比研究了一类双席夫碱及其衍生物与金属Co、Ni和Cu配位后配合物的结构,非线性光学性质以及激发态性质.结果表明,Co配合物的三重态,Ni配合物的二重态以及Cu配合物的单重态为最佳稳定结构.通过最佳稳定结构计算得到的配合物非线性光学性质表明,三种金属配合物中Cu配合物表现出较高的一阶和二阶超极化率.通过对其激发态性质分析表明在配体苯环上引入甲氧基使电子跃迁种类减少,导致超极化率下降,非线性光学性质减弱. 相似文献
976.
Aromatic nitro compounds were reduced to respective amines in high yields by using 5% platinum on carbon with ammonium formate or formic acid as hydrogen donor. It was observed that the former was more efficient donor than the later. Further we have found that reduction of nitro groups occurs without hydrogenolysis of halogens and the reducible substituents which remains unchanged under the reaction conditions. 相似文献
977.
A simple and efficient procedure for the synthesis of symmetrical bis-Schiff bases has been described that employs a condensation reaction of symmetrical primary bis-amine of 5,5′-methylenebis(2-aminothiazole) with a series of aromatic aldehyde derivatives under solvent-free conditions at elevated temperature. The advantages of these reactions are simplicity of the reaction procedure, short reaction times, simple workup, catalyst-free conditions, and pure products in good to excellent yields. Details of the reaction conditions are discussed. 相似文献
978.
Functionalised α, β-unsaturated aldehydes were exclusively reduced to allylic alcohols with sodium-triacetoxyborohydride. Neither saturated alcohol nor saturated aldehydes are obtained. Conjugated ketones are not reduced. 相似文献
979.
Şaban Uysal 《合成通讯》2013,43(1):84-92
2,4,6-Tris(4-hydroxybenzimino)-1,3,5-triazine (II) has been synthesized by the reaction of 1 equiv. melamine (I) and 3 equiv. 4-hydroxybenzaldehyde and characterized by means of elemental analysis, 1H NMR, Fourier transform–infrared spectroscopy, and liquid chromatography–mass spectrometry (LC-MS). 2,4,6-tris(4-(2-phenyl-2-keto-hydroxyiminoyloxy)benzimino)-1,3,5-triazine L (III) has been synthesized by the reaction of 1 equiv. II and 3 equiv. chloroisonitrozoacetophenone and characterized by means of the same methods. Four novel trinuclear Fe(III) and Cr(III) complexes involving tetradentate Schiff bases N,N′-bis(salicylidene)ethylenediamine-(salenH2) or bis(salicylidene)-o-phenylenediamine-(salophen H2) with L (III) have been synthesized and characterized by means of elemental analysis, Fourier transform–infrared spectroscopy, LC-MS (ESI+), and thermal analyses. The metal ratios of the prepared complexes have been determined using atomic absorption spectroscopy. The aim of the present study is to synthesize novel tridirectional-trinuclear systems and to present their effects on magnetic behavior of [salen or salophenFe(III)/Cr(III)] capped complexes. The complexes have also been characterized as low-spin distorted octahedral Fe(III) and as distorted octahedral Cr(III) bridged by keton-oxime group. 相似文献
980.
Gunnar Aksnes 《Phosphorus, sulfur, and silicon and the related elements》2013,188(2):227-238
Abstract The 1,2,3-trithiolan of endo-dicyclopentadiene, C10H12S3 (1) can be polymerized to give low molecular weight polymers (C10H12S3)n, n = 3–6, by heating or by exposure to UV irradiation. The polymers differ according to the method of polymerization as revealed by their n.m.r. spectra. Depolymerization of both types of polymer can be achieved by heating with amines, and especially with R3N. Desulphurization of (1) by Na2SO3 or triphenylphosphine produces a polymer of composition (C10H12S2)n, n= ca 18–19. The depolymerization of this material by Et3N regenerated some (1). 相似文献