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91.
A.K. Srivastava Neerja Shukla Avni Pandey Akanchha Srivastava 《Journal of Saudi Chemical Society》2011,15(3):215-220
G-protein coupled receptors like Bradykinin (BK) B1 represent a potential treatment route for chronic pain and inflammation. Quantitative structure activity relationship has been performed on a series of α-hydroxy amides as a novel class of bradykinin B1 selective antagonists, using different physicochemical parameters along with appropriate indicator variables. It has been found that physicochemical parameters such as connectivity indices 3χ, 4χ and 5χ, molecular weight, molar refractivity, density along with indicator variables are significantly correlated with activity. In this paper best results were obtained by using multiple regression analysis. Different models were generated with high values of R2 and low values of PRESS/SSY ratio. The significant equations were statistically tested by using leave one out (LOO) technique and cross validation methods. 相似文献
92.
Benzyl chloride was treated with (Me3Si)3CLi to give (Me3Si)3CCH2Ph (1). A new styrene derivative, (Me3Si)3CCH2C6H4(CHCH2-p) (2), was synthesized by reaction of p-vinylbenzyl chloride with (Me3Si)3CLi in the presence of CuCl. Addition and oxidation reactions on 2 gave a series of new compounds (Me3Si)3CCH2C6H4X-p (X = CH2CH3, CHBrCH2Br, CHClCH2I, CHBrCH2I, cyclo-C3H3Cl2, CHOHCH2OH, COOH, CH2OH). 相似文献
93.
Studies on the synthesis of a sterically congested analogue of CC-1065 (2) are described. Interesting steric effects in the reactivity of intermediates and the rare predominance of keto tautomers in some phenols were observed. 相似文献
94.
Lijun Wang Baohui Li Qinghua Jin Zhenya Guo Shixiong Tang Datong Ding 《Journal of molecular catalysis. A, Chemical》2000,160(2):377-381
Molecular simulation is applied to explain the diastereoselective thio-Claisen rearrangement results of various S-allyl γ-hydroxy ketene dithioacetals. We show that the experimental results of Sreekumar et al. in the absence and in the presence of zeolite catalyst can be rationalized in terms of the energetics of the steric of the reactant and the transition-state structure and of the non-bonding interactions of zeolite–reactant and zeolite–transition-state structure. The procedures used can successfully identify optimum products for a given diastereoselective thio-Claisen rearrangement. 相似文献
95.
Alexander Zeller 《Journal of organometallic chemistry》2005,690(13):3292-3299
Via NMR-spectroscopy the relative reactivity of N-heterocyclic silylenes (NHSi) and carbenes (NHC) was studied. Reaction of sterically crowded bis-N-heterocyclic Pd(0) carbene complexes with free N-heterocyclic silylenes led to complete displacement of the N-heterocyclic carbene, which is unexpected knowing that usually a silylene is a weaker bound ligand compared to a carbene. High-level DFT calculations on a small model system and the experimentally used complexes confirm the experimental findings and indicate that steric interactions play an important role in the substitution reaction. 相似文献
96.
Jeffrey M. Coles Debby P. Chang Stefan Zauscher 《Current Opinion in Colloid & Interface Science》2010,15(6):406-416
Mucins have long been recognized as instrumental to biolubrication but the molecular details of their lubrication mechanisms have only been explored relatively recently. The glycoprotein PRG4, also known as lubricin, shares many features with mucins and appears to lubricate through similar mechanisms. A number of studies have contributed to a more in-depth understanding of mucin adsorption and layer formation on surfaces and the mechanisms by which these layers lubricate. Although mucinous glycoproteins differ in their aggregation properties, their adsorption behaviors on surfaces, and in their ability to reduce friction, they share important similarities favorable for lubrication. They are highly hydrated, they adsorb strongly to a broad range of surfaces, and the layers they form are both sterically and electrostatically repulsive, all attributes thought to contribute to boundary lubrication. They also hydrophilize hydrophobic surfaces, promoting the formation of aqueous fluid films that can lower friction at already relatively low sliding speeds. In this paper we briefly review current knowledge of mucin adsorption and lubrication, with a focus on recent advances. 相似文献
97.
Sterically controlled regioselective lithiation of meta-halopyridocarboxamides derivatives using deuterated probes is described. A first experimental demonstration that the nitrogen is the main chelating-base approach site onto the oxazoline and N-alkoxyamide DMGs is reported. 相似文献
98.
《Comptes Rendus Chimie》2015,18(2):127-131
Application of an N–C bond cleavage reaction in various structurally complex molecular frameworks containing bridge-head nitrogen atom offered differential outcomes that were attempted to rationalize invoking both steric and electronic factors. 相似文献
99.
Satinder V. Kessar Paramjit Singh Kamal Nain Singh P. Venugopalan Amarjit Kaur Manu Mahendru Rajiv Kapoor 《Tetrahedron letters》2005,46(39):6753-6755
Lithiation of a series of cyclic aralkyl tertiary amines with sec-BuLi in various solvents has been studied. There is a subtle sensitivity to steric factors and lithium coordinating solvents/additives have an adverse effect. ortho-Lithiation is observed only in the case of an eight-membered cyclic amine and the ease of benzylic lithiation with respect to nitrogen is in the surprising order γ > β ? α, δ. These observations are discussed in the context of nitrogen coordination promoted lithiation. 相似文献
100.
From the very extensive factual material available on steric interactions in organic chemistry, the present paper reviews the investigations that provide information about the “size” (“spatial requirement”) of the substituents. After an introductory section on the results obtained with the aid of spectroscopic data and by analysis of chemical reactions, attention is turned to conformational processes, including hindered rotation in ethanes, in the biphenyl system, in butadienes, multiply substituted arenes, molecular propellers, and triptycenes. The main emphasis is placed on the explanation of sterically hindered ring inversions in bridged arenes, a class of compounds particularly suitable for the study of steric interactions. The results obtained by variation of the parameters in this system are also discussed with respect to the spatial requirements of organic substituents. 相似文献