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41.
Wen-Feng Liaw Chia-Huei Lai Ming-Hsi Chiang Cheng-Kang Hsieh Gcne-Hsiang Lee Shie-Ming Peng 《中国化学会会志》1993,40(5):437-444
Diphenyldichalcogenides (PhE)2 (E = Te, Se) react with Fe(0)-phenylchalcogenolate [PPN] [PhEFe(CO)4] to yield the products of oxidative addition, Fe(II)-mixed-phenylchalcogenolate fac- [PPN][Fe(CO)3(TePh)n(ScPh)3-n] (n = 1, 2). Reactions of [PPN][REFe(CO)4] (E=Se, R=Me; E=S, R=Et) and diphenyldichalcogenides yielded ligand-exchange products [PPN][PhEFe(CO)4] (E=Te, Se, S). The compounds [Fe(CO)3(TePh)(ScPh)2]? (l) and [Fe(CO)3(TePh)2 (2) crystallize in the isomorphous monoclinic space group C2/e, with a = 32.035(8), b = 11.708(6), c = 28.909(6) Å, Z = 8, R = 0.048, and Rw = 0.044 (1); with a = 32.089(5), b= 11.745(2), c = 28.990(8) Å, Z = 8, R = 0.048, and Rw = 0.048 (2). The complexes 1 and 2 crystallize as discrete cations of PPN+ and anions of [Fe(CO)3(TcPh)u(ScPh)3-n] (n=1, 2), and one half solvent molecule THF. The geometry around Fe(II) is a distorted octahedron with three carbonyl groups and three phenylchalcogenolate ligands occupying facial positions. 相似文献
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A simple method is presented for the one-pot synthesis of monodisperse MnO nanoparticles (NPs) using bulk MnO as the starting material. In the proposed approach, bulk MnO powder is dissolved in hot oleic acid to form manganese oleate (Mn(RCOO)2) and a decomposition process is then performed to obtain MnO NPs. The proposed method is environmentally friendly in that the only by-product is water, which can be easily distilled out. Conceptually, the synthesis method can be viewed as a controlled dissolution recrystallization process. It is shown that the size of the NPs can be controlled over the range of 6–32 nm via an appropriate specification of the precursor-to-oleic acid ratio and the reaction temperature (by the choice of an appropriate high b.p organic solvent). Finally, the size-dependent magnetic properties of three different monodisperse MnO NPs (7.7 nm, 19.4 nm and 31.7 nm) are studied. It is shown that the monodisperse MnO NPs exhibit a weak ferromagnetic behavior due to uncompensated surface spins at low temperatures. 相似文献
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Chia YC Chang FR Wang JC Wu CC Chiang MY Lan YH Chen KS Wu YC 《Molecules (Basel, Switzerland)》2008,13(1):122-128
Using a bioactivity-guided fractionation method, two coumarins: minumicroline acetonide (1) and epimurpaniculol senecioate (2), were isolated from the leaves of Murraya omphalocarpa Hayata (Rutaceae). Compound 1 had been previously synthesized and was now isolated from natural sources for the first time, and compound 2, possessing a negative optical rotation value, is new. The structures and their stereochemistry were fully elucidated on the basis of spectroscopic and X-ray crystallographic techniques. Both compounds 1 and 2 are active in the antiplatelet aggregation assay. Interestingly, the possible acetonide artifact 1 displayed significant antiplatelet aggregation induced not only by AA and collagen but also by platelet activating factor (PAF). 相似文献
47.
Hsu YH Chiang WH Chen MC Chern CS Chiu HC 《Langmuir : the ACS journal of surfaces and colloids》2006,22(16):6764-6770
The effects of SDS on the structural changes of the thermally induced polymeric micelles from a graft copolymer comprising poly(acrylic acid) (PAAc) as the backbone and poly(N-isopropylacrylamide) (PNIPAAm) and monomethoxy poly(ethylene glycol) (mPEG) as the grafts in aqueous solution are studied. At low temperature, SDS micelles form via the hydrophobic association of SDS molecules with the PNIPAAm grafts at a critical aggregation concentration of SDS (cac(SDS)) much lower than its critical micelle concentration. Consequently, the critical aggregation temperature of the graft copolymer is elevated. The corresponding structure of the thermally induced polymeric micelles is characterized by an abrupt reduction in the particle size and an increased tendency toward formation of the monocore structure with a more compact and hydrophobic PNIPAAm microdomain being developed. On the other hand, upon the polymeric micelle formation at high temperature, the copolymer-bound SDS micelle structure is disrupted and the dissociated SDS molecules migrate to the core-shell interface with their alkyl chains residing in the liquidlike region of the hydrophobic PNIPAAm microdomain. The correlation between the polymeric particles and copolymer-bound micelles is further substantiated by showing the change of the colloidal particle size in response to changes in cac(SDS) via adjusting the pH of the aqueous copolymer/SDS solutions. 相似文献
48.
Chunlan Song Xin Dong Zhongjie Wang Kun Liu Chien‐Wei Chiang Aiwen Lei 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(35):12334-12338
The [4+2] annulation represents an elegant and versatile synthetic protocol for the construction of benzene rings. Herein, a strategy for visible‐light induced [4+2] annulation of thiophenes and alkynes, to afford benzene rings, is presented. Under simple and mild reaction conditions, the ready availability and structural diversity of thiophenes and alkynes permit the facile synthesis of several substituted aromatic rings. Valuable drugs and amino acids are also well tolerated. Moreover, DFT calculations explain the high regioselectivity of the reaction. 相似文献
49.
Absalon C Fabre S Tarascou I Fouquet E Pianet I 《Analytical and bioanalytical chemistry》2011,401(5):1489-1499
Tannins represent a key element in red wine flavors, so researchers have made a lot of effort to try to understand the role
of their structure in wine taste in recent decades. We report some new routes to achieve a true structure–taste relationship
for the major tannins found in wine, which are procyanidins in their monomeric or oligomeric state. All these routes use synthetic
standards. New advances in their synthesis and their analyses using chromatographic methods, NMR spectroscopy, and mass spectrometry
to obtain more precise information about their chemical structure, including their stereochemistry and their precise degree
of polymerization and galloylation, are described. 相似文献
50.
Laurel Ng Alan J. Grodzinsky John Sandy Anna Plaas Christine Ortiz 《Macromolecular Symposia》2004,214(1):1-4
Tapping mode atomic force microscopy (TMAFM) was employed to directly calculate the persistence length of individual fetal bovine epiphyseal and mature nasal cartilage aggrecan monomers, as well as their constituent chondroitin sulfate glycosaminoglycan chains. 相似文献