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151.
152.
It is unknown whether or not there exists an [87, 5, 57; 3]-code. Such a code would meet the Griesmer bound. The purpose of this paper is to give a constructive proof of the existence of [q
4 + q
2 – q, 5, q
4 – q
3 + q
2 – 2q; q]-codes for any prime power q 3. As a special case, it is shown that there exists an [87, 5, 57; 3]-code with weight enumerator 1 + 156z
37 + 82z
60 + 2z
63 + 2z
78. The new construction settles an open problem due to Hill and Newton [10]. 相似文献
153.
Renato Sonchini Gonçalves Expedito Leite Silva Noboru Hioka Celso Vataru Nakamura Marcos Luciano Bruschi Wilker Caetano 《Natural product research》2018,32(3):366-369
Different from works described in the literature, which use expansive analytical methods to separation of anthraquinones derivatives (AQs), this communication reported a simple and inexpensive methodology to get them. In this way, the expensive commercial AQs: Chrysophanol, physcione and emodine were extracted from plant material (Rhamnus frangula L.) and isolated by classical column chromatography technique under optimised binary mobile phase gradients (CHCl3 : AcOEt(a), a = 1 to 5%) in excellent yields. 相似文献
154.
Takashi Saito Seikichi Yasoshima Hiroshi Masuhara Noboru Mataga 《Chemical physics letters》1978,59(2):193-196
Fluorescence quenching rate constants of aromatic hydrocarbons by silver ions are determined. The values obtained are not well interpreted with thermodynamical considerations based on an electron transfer mechanism, but related to the intersystem crossing rate constant of the fluorescer. Triplet state formation in the course of quenching has been confirmed by laser photolysis studies. 相似文献
155.
Nishino T Okada M Kuroki T Watanabe T Nishiyama Y Sonoda N 《The Journal of organic chemistry》2002,67(24):8696-8698
A convenient synthetic method of unsymmetrical selenides has been developed. When diphenyl diselenide was allowed to react with two equimolar amounts of primary alkyl iodides and bromides in the presence of an equimolar amount of lanthanum metal, alkyl phenyl selenides were formed in moderate to good yields. For the reaction of primary alkyl chlorides and secondary alkyl iodides, the yields of the selenides were low; however, the yields were dramatically improved by the addition of TMEDA or HMPA. A reaction pathway involving the generation of a lanthanum phenylselenolate intermediate was suggested. 相似文献
156.
When elemental selenium was added to a strongly basic amine, 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) or 1,5-diazabicyclo[4.3.0]non-5-ene (DBN), the selenium started to dissolve and the solution turned dark brown. We investigated the chemical reaction of this selenium dissolution process by electrospray ionization mass spectrometry (ESI-MS). The study reveals for the first time that cleavage of Se-Se bonds by the amine initiates the reaction to form molecular Se2, which then abstracts hydrogen from the amine molecule. ESI-MS with the use of a nanospray technique was shown to be a useful tool for studying the dissolution of elements in strongly basic or acidic solvents. 相似文献
157.
158.
[reaction: see text] Lithium enolates of ketones and aldehydes undergo carbonylation with carbon monoxide with the aid of selenium under mild conditions to yield beta-keto and beta-formyl selenol esters after trapping with alkyl iodides. This reaction proceeds via a unique carbonylation mechanism comprised of O-carbonylation and subsequent migration of the SeCO moiety to the alpha-carbon. 相似文献
159.
Kunihiro Ichimura Noboru Oohara 《Journal of polymer science. Part A, Polymer chemistry》1987,25(11):3063-3077
Three methods to introduce photodimerizable styrylpyridinium or styrylquinolinium groups to methacrylate polymers are described. Among these, copolymerization of methacrylate monomers with methacrylated styrylpyridine or styrylquinoline offered the most convenient procedure to prepare photosensitive polymers because of the excellent solubility of the polymers having the photofunctional groups in high content. Subsequent treatment with p-toluenesulfonic acid to quaternize the pyridine or quinoline moiety made the polymer highly photosensitive. The polymers having a styrylquinolinium group were found to be sensitive to 488 nm light of an Ar laser, and the sensitivity was about 3 mJ/cm2 when the content of the photosensitive group was 15 mol %. 相似文献
160.
The reactions of some diorganonickel(II) complexes with N-bromosuccinimide (NBS) resulted in facile bromine for hydrogen substitution in aromatic, alkynyl or alkenyl substituents, or in the addition of NBS to CC bonds. 相似文献