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111.
An impulsive Cohen–Grossberg-type bidirectional associative memory (BAM) neural networks with distributed delays is studied. Some new sufficient conditions are established for the existence and global exponential stability of a unique equilibrium without strict conditions imposed on self regulation functions. The approaches are based on Laypunov–Kravsovskii functional and homeomorphism theory. When our results are applied to the BAM neural networks, our results generalize some previously known results. It is believed that these results are significant and useful for the design and applications of Cohen–Grossberg-type bidirectional associative memory networks. 相似文献
112.
Wouters J Yin F Song Y Zhang Y Oudjama Y Stalon V Droogmans L Morita CT Oldfield E 《Journal of the American Chemical Society》2005,127(2):536-537
We report the crystallographic structures of the potent phosphoantigens Phosphostim (the bromohydrin of isopentenyl pyrophosphate) and E-4-hydroxy-3-methyl-but-2-enyl pyrophosphate bound to the mevalonate pathway enzyme isopentenyl pyrophosphate/dimethylallyl pyrophosphate isomerase (IPPI). Racemic Phosphostim forms covalent complexes with IPPI: a 4-thioether with C67 and a 4-ester with E116. Only the E116 ester forms with the chiral species, S-Phosphostim, with the w.t. enzyme, while the C67 thioether forms with a mutant Y104F IPPI. The potent phosphoantigen HMBPP also binds to IPPI, but is only a weak ( approximately 50 muM) inhibitor. These results strongly support an SN2 reaction for inhibition of IPPI by Phosphostim, in contrast to the SN1 or concerted type of reaction found with epoxide inhibitors, which react at C-3, and are of general interest in the context of the development of novel mevalonate pathway inhibitors. They also provide clues as to the nature of the binding site of synthetic phosphoantigens in gammadelta T cell activation. In particular, both bromohydrin and epoxy phosphoantigens are potent, irreversible inhibitors of IPPI while HMBPP is only a weak inhibitor, ruling out an IPPI or IPPI-like target for HMBPP in gammadelta T cell activation. 相似文献
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高效液相色谱法检测多种食品基体中残留的喹氧灵 总被引:1,自引:1,他引:0
建立了采用液相色谱检测大豆、花椰菜、樱桃、木耳、葡萄酒、茶叶、蜂蜜、猪肝、鸡肉、鳗鱼等多种食品基体中喹氧灵残留的方法。利用乙酸乙酯提取样品中残留的喹氧灵,用氨基固相萃取小柱净化;对于脂肪含量较高的样品,在进行固相萃取前采用凝胶渗透色谱净化技术去脂。方法的准确度与精密度较好,在添加浓度为0.010~5.0 mg/kg时,平均回收率及相对标准偏差分别为82%~96%及3.2%~11.8%;在0.050~50.0 mg/L范围内有良好的线性关系,检测限达0.010 mg/kg。该方法适用性广,能消除复杂基质带来的干扰,可用于各类食品中喹氧灵残留的分析。 相似文献
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hoto-responsive azobenzene (ABZ) derivatives with different end groups (R) were employed to construct selfassembled monolayers (SAMs) on silicon substrates. The SAMs based on hydrophilic (4-(4'-aminophenylazo) benzoic acid, ABZ-COOH) show excellent reversible photoswitching performance with a large contact angle change of 35° under optimized process. 相似文献
119.
Xiaopo Zhang Shuai Wang Yonghui Li Dan Zhao Ni An Jiani Wu 《Natural product research》2015,29(24):2287-2290
Tadehaginoside (TS) is a phenylpropanoid glycoside found in Tadehagi triquetrum, a medicinal plant with multiple biological activities. This study investigated the effect of TS on lipogenesis and glucose consumption in HepG2 cells. Treatment with TS inhibited lipid accumulation in a dose-dependent manner. This inhibition was closely associated with the downregulation of lipogenic genes such as SREBP-1a, SREBP-2 and their downstream targets (FAS, ACC, HMGR) and the upregulation of lipolytic gene PPARα as revealed by real-time quantitative PCR. Further investigation showed that TS significantly stimulated glucose consumption by HepG2 cells and glucose uptake by C2C12 myotubes, which could be partially explained by the upregulation of PPARγ. Collectively, these results clearly indicate that TS is an effective regulator of lipogenesis and glucose consumption, which could be useful in treatment of obesity and diabetes. 相似文献
120.