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881.
α-Bromoacetals of ketones were prepared from various secondary alcohols with 1,3-dibromo-5,5-dimethylhydantoin (DBDMH) and ethylene glycol through oxidation, bromination, and acetalization in one pot without the use of other catalysts under mild conditions. The effects of DBDMH, the solvent, and N-bromosuccinimide on the reaction were investigated. Under the optimal conditions, most α-bromoacetals of ketones were obtain in 90–98% yields. 相似文献
882.
Wei Wu Yingcai Ding Ping Xie Qiujie Tang Charles U. Pittman Aihua Zhou 《Tetrahedron》2017,73(15):2151-2158
Structure containing the CS bond exist widely in nature, drugs and chemical materials. Here, a novel sulfenylation protocol employing an aryl or alkyl halide and odorless and cheap S as reagents was developed, generating regioselective alkyl-S- and Ar-S-substituted imidazol[1,2-α]pyridine derivatives in good yields under relatively environmentally friendly and mild conditions. This protocol enriches current thioether-producing methods, making up for the shortcomings of previous sulfenylation methods which can only make MeS- and ArS-substituted imidazol[1,2-α]pyridine derivatives. 相似文献
883.
The domino reactions of 2-fluoro benzensulfonyl acetonitrile and α-chloro oximes in the presence of Cs2CO3 in aprotic high boiling point solvents have been achieved to provide isoxazole?fused 4H-1,4-benzothiazine-4,4-dioxides via an unprecedented transition metal-free one-pot addition/cyclization process. The tunable synthesis of either isoxozolo-1,4-benzothiazin-4-oxides or their precursor 5-aminoisoxazoles can be controlled depending on the solvent selection. The observed products were characterized by means of (IR, 1H, 13C NMR and HRMS) and physical methods. 相似文献
884.
A highly enantioselective 1, 3-dipolar cycloaddition of nitrone with α, β-unsaturated acyl phosphonate was developed for the first time by using a chiral indane-bis(oxazoline)-copper(II) complex. The reaction proceeded smoothly under mild conditions to provide isoxazolidines with multi-stereocenters in good yields with high to excellent diastereo- (>20:1 dr) and enantioselectivities (up to 99% ee). The resulting products were readily converted to multi-functional isoxazolidines or γ-amino alcohol compounds. 相似文献
885.
Rajesh H. Vekariya 《合成通讯》2017,47(2):87-104
The α-thiocyanation of carbonyl compounds is one of the most important processes in synthetic organic chemistry. These compounds are important precursors for the production of various biologically important heterocyclic compounds and other industrially important products. Ammonium thiocyanate (NH4SCN) is a key reagent for the production of such a class of thiocyanate intermediates. In addition to the inherent efficiency issues, there are also environmental concerns that need to be addressed. Therefore, in recent years considerable advances have been made for the synthesis of α-thiocyanation of carbonyl compounds with high selectivity and yield. In this review, we have summarized various methods for the synthesis of α-thiocyanation carbonyl compounds. 相似文献
886.
A stereoselective route to an advanced intermediate toward the synthesis of clavosolide A is disclosed. The key steps include Wadsworth-Emmons cyclopropanation, utilization of a sulfinyl moiety as an internal nucleophile to open a cyclopropane ring activated by Hg(II)- to create the C3-C5 stereogenic centers, CC bond formation employing an α-chloro sulfide, asymmetric transfer hydrogenation, regioselective hydrosilylation and Tamao-Fleming oxidation. 相似文献
887.
Truc T.T. Duong Truong N.V. Do Hai X. Nguyen Tho H. Le Phu H. Dang Nhan T. Nguyen Tuyen N.T. Nguyen Thao D. Nguyen Mai T.T. Nguyen 《Tetrahedron letters》2017,58(23):2280-2283
Two new neolignans, named rebaneolignan A (1) and B (2), were isolated from the stem of Mangifera reba (Anacardiaceae), together with six known compounds (3–8). Their structures were elucidated on the basis of NMR spectroscopic analysis and the absolute configurations of 1 and 2 were determined by NOESY and CD data. All isolated compounds were found to possess more potent inhibitory activity, with IC50 values ranging from 28.5 to 162.8 µM, than the positive control acarbose (IC50, 214.5 µM). Plausible biosynthetic pathways for the formation of 1 and 2 were proposed based on the oxidative β-5′ coupling reactions. 相似文献
888.
The N,N-dimethylhydrazone of 1,1,1-trifluoroacetone, (E)-1,1-dimethyl-2-(1,1,1-trifluoropropan-2-ylidene)hydrazine, has been shown to undergo a diverse set of reactions following deprotonation with n-butyl-lithium; including alkylation, addition to ketones and aldehydes, as well as palladium-catalyzed cross-couplings with aryl bromides. Mild hydrolysis of the N,N-dimethylhydrazone products from these transformations affords the corresponding trifluoromethyl ketones in good to excellent yields. 相似文献
889.
Two new α-aminophosphonate derivatives containing thieno[2,3-d]pyrimidine, diethyl(((6-ethyl-2-methyl-4-oxothieno[2,3-d]pyrimidin-3(4H)-yl)amino)(4-methoxyphenyl)methyl)phosphonate(1) and diethyl((4-bromophenyl)((6-ethyl-2-methyl-4-oxothieno[2,3-d]pyrimidin-3(4H)-yl)amino)methyl)phosphonate(2), have been synthesized by a facial phosphorylated reaction, and their structures were characterized by NMR, IR, HRMS and X-ray single-crystal diffraction. Compound 1(C21H28N3O5PS, Mr = 465.49) belongs to the orthorhombic system, space group P212121, with a = 10.83653(16), b = 12.04906(19), c = 18.0061(3) , V = 2351.06(6) 3, Z = 4, Dc = 1.315 g/cm3, μ = 2.177 mm-1, F(000) = 984.0, the final R = 0.0389 and w R = 0.0985 for all data. Compound 2(C20H25Br N3O4 PS, Mr = 514.37) belongs to the orthorhombic system, space group P212121, with a = 10.9187(5), b = 11.9522(4), c = 17.7667(7) , V = 2318.60(16) 3, Z = 4, Dc = 1.474 g/cm3, μ = 4.175 mm-1, F(000) = 1056.0, the final R = 0.0367 and w R = 0.0946 for all data. 相似文献
890.
以配合物乙酰丙酮铁为前驱体,利用超声雾化的方法进行化学气相沉积制备α-Fe2O3薄膜,并对其结构和性能进行测试表征。 相似文献