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991.
Graham Smith Daniel E. Lynch 《Acta Crystallographica. Section C, Structural Chemistry》2016,72(2):105-111
The morpholinium (tetrahydro‐2H‐1,4‐oxazin‐4‐ium) cation has been used as a counter‐ion in both inorganic and organic salt formation and particularly in metal complex stabilization. To examine the influence of interactive substituent groups in the aromatic rings of benzoic acids upon secondary structure generation, the anhydrous salts of morpholine with salicylic acid, C4H10NO+·C7H5O3−, (I), 3,5‐dinitrosalicylic acid, C4H10NO+·C7H3N2O7−, (II), 3,5‐dinitrobenzoic acid, C4H10NO+·C7H3N2O6−, (III), and 4‐nitroanthranilic acid, C4H10NO+·C7H5N2O4−, (IV), have been prepared and their hydrogen‐bonded crystal structures are described. In the crystal structures of (I), (III) and (IV), the cations and anions are linked by moderately strong N—H…Ocarboxyl hydrogen bonds, but the secondary structure propagation differs among the three, viz. one‐dimensional chains extending along [010] in (I), a discrete cyclic heterotetramer in (III), and in (IV), a heterotetramer with amine N—H…O hydrogen‐bond extensions along b, giving a two‐layered ribbon structure. With the heterotetramers in both (III) and (IV), the ion pairs are linked though inversion‐related N—H…Ocarboxylate hydrogen bonds, giving cyclic R44(12) motifs. With (II), in which the anion is a phenolate rather than a carboxylate, the stronger assocation is through a symmetric lateral three‐centre cyclic R12(6) N—H…(O,O′) hydrogen‐bonding linkage involving the phenolate and nitro O‐atom acceptors of the anion, with extension through a weaker O—H…Ocarboxyl hydrogen bond. This results in a one‐dimensional chain structure extending along [100]. In the structures of two of the salts [i.e. (II) and (IV)], there are also π–π ring interactions, with ring‐centroid separations of 3.5516 (9) and 3.7700 (9) Å in (II), and 3.7340 (9) Å in (IV). 相似文献
992.
Chloroacetate Promotes and Participates in the Oxidative Annulation of Pyridines/Isoquinoline by Using Oxygen as the Oxidant
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Dr. Yuanyuan Yue Yangyang Sun Shufang Zhao Xuyang Yan Rong Li Yaru Shi Dr. Kelei Zhuo Dr. Jianming Liu 《化学:亚洲杂志》2016,11(23):3339-3344
The aerobic oxidative annulation of chalcones, pyridines/isoquinoline and ethyl chloroacetate to indolizines was achieved by cascade reaction. Various functional groups on chalcones were tolerated. And different pyridines derivatives could also be suitable substrates. Ethyl chloroacetate is an essential component in participating of the oxidative annulation process. Overall, this protocol is very practical and efficient by using molecular oxygen as oxidant with high selectivity for the annulation product. 相似文献
993.
取代吡啶与双过氧钒配合物相互作用的NMR和理论研究 总被引:1,自引:0,他引:1
为探讨有机配体上取代基团对反应平衡的影响, 在模拟生理条件下(0.15 mol/L NaCl溶液), 应用多核(1H, 13C和51V)多维(DOSY)以及变温NMR技术研究双过氧钒配合物[OV(O2)2(D2O)]-/[OV(O2)2(HOD)]-(简写为bpV)与取代吡啶的相互作用. bpV与有机配体的反应性从强到弱的顺序为: 皮考林酸根>异烟酸根>异烟酸甲酯>皮考林甲酯, 这说明吡啶环上同一位置上的不同取代基团和同一取代基团在不同位置上都影响反应平衡, 竞争配位导致一系列新的6配位(配体为异烟酸根和异烟酸甲酯)或7配位(配体为皮考林酸根和皮考林甲酯)的过氧钒物种[OV(O2)2L]n- (L=取代吡啶, n=1或2)生成, 密度泛函计算结果较合理地解释了实验结果, 并表明溶剂化在反应中起重要作用. 相似文献
994.
Heng-Shan Wang Ying-Chun Wang Ying-Ming Pan Zhen-Feng Chen 《Tetrahedron letters》2008,49(16):2634-2637
An efficient method for palladium-catalyzed Suzuki cross-coupling reaction with simultaneous reduction of nitro- to amino-group has been developed. This method allows nitro-substituted aryl halides to readily react with arylboronic acids, to afford aryl substituted aniline in low to excellent yields. The reaction was catalyzed by Pd(OAc)2 (3 mol %) at 150 °C under atmospheric pressure in the presence of K2CO3 (3 equiv) in DMF/H2O (5/1). 相似文献
995.
S. A. Yamashkin N. V. Zhukova I. S. Romanova 《Chemistry of Heterocyclic Compounds》2008,44(7):793-801
It was established that the initial condensation of substituted 6-aminoindoles and oxaloacetic ester in boiling benzene with
the addition of catalytic amounts of acetic acid takes place exclusively through the carboxyl group of the keto ester with
the formation of the corresponding enamines, which successfully undergo thermal cyclization (biphenyl, 280°C) to pyrroloquinolines.
Here, irrespective of the nature of substituents at the N-1 and C-5 atoms enamines with a free position 7 are transformed
into pyrrolo-[2,3-f]quinolines (structural analogs of vitamin PQQ) while 7-OMe-substituted enamines give pyrrolo[3,2-g]quinolines
with linear fusion of the rings.
__________
Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 991–1002, July, 2008. 相似文献
996.
Condensation of aromatic aldehydes with cyclopentanone and cyclohexanone using amino‐functionalized ionic liquid, 1‐aminoethyl‐3‐methyl tetrafluoroborate as solvent and catalyst was successfully performed for preparation of α,α′‐bis(substituted benzylidene)cycloalkanones. The catalyst can be recovered and reused for at least three times without apparently lose of activity. The process is simple, environmentally benign and proceeds in excellent yields. 相似文献
997.
Cyclocondensation of polystyrene‐supported α‐selenopropionic acid with amidoximes in the presence of 1‐(3‐dimethylaminopropyl)‐3‐ethylcarbodiimide hydrochloride (EDC) followed by oxidative deselenation efficiently afforded 5‐vinyl 1,2,4‐oxadiazoles in good yield and purity with a facile work‐up procedure. 相似文献
998.
A series of 14‐{[(Un)substituted phenyl] or alkyl}‐14H‐dibenzo[a,j]xanthenes were prepared under solvent‐free conditions by Yb(OTf)3 catalyzed condensation reactions of β‐naphthol with various aldehydes. The process presented here is operationally simple, environmentally benign and has good to excellent yields. Furthermore, the catalyst can be recovered conveniently and reused efficiently. 相似文献
999.
1000.
Wheelock CE Colvin ME Sanborn JR Hammock BD 《Journal of mass spectrometry : JMS》2008,43(8):1053-1062
Analysis of ethyl 3-(2-chlorophenyl)propenoate by electron ionization mass spectrometry showed the distinct loss of an ortho chlorine. To characterize the structural requisites for the observed mass fragmentation, a series of 30 halogen-substituted 3-phenylpropenoate-related structures were examined. All ester-containing alkene derivatives exhibited loss of the distinctive chlorine from the 2-position of the phenyl ring. Analogous derivatives with the halogen (chlorine or bromine) in the para position did not evidence selective halogen loss. Results demonstrated that substituted 3-phenylpropenoates and their analogs fragment via the formation of a previously reported benzopyrylium intermediate. To understand the correlation between the intramolecular radical substitution and the abundance and selectivity of the chlorine (or other halogen) displacement, density functional theory calculations were performed to determine the charge on the principal cation involved in the chlorine loss (in the ortho, meta, and para positions), the charge for the neutral radical (noncation), the excess alpha-electron density on the relevant atom and the energy to form the cation from the neutral atom (ionization energy). Results showed that the selectivity and extent of halogen displacement correlated highly to the electrophilicity of the radical cation as well as the neutral radical. These data further support the proposed fragmentation mechanism involving intramolecular radical elimination. 相似文献