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Li G Mehta R Srikrishnan T Nurco DJ Tabaczynski WA Alderfer JL Smith KM Dougherty TJ Pandey RK 《Chemical communications (Cambridge, England)》2002,(11):1172-1173
Reaction of meso-(2-formylvinyl)octaethylporphyrin with (CH3)3SiCN-Cu(OTf)2 produced unexpected 10(3)-trimethylsiloxyl and 10(3)-hydroxyl fused propenochlorins which, in H2SO4, underwent subsequent migration of the 8-ethyl group to the 10(3)-position of the exocyclic benzene ring to form a novel benzochlorin. 相似文献
74.
Li G Pandey SK Graham A Dobhal MP Mehta R Chen Y Gryshuk A Rittenhouse-Olson K Oseroff A Pandey RK 《The Journal of organic chemistry》2004,69(1):158-172
meso-(2-Formylvinyl)octaethylporphyrin on reaction with cyanotrimethylsilane in the presence of various catalysts [copper triflate [Cu(OTf)(2)], indium triflate [In(OTf)(3)], or magnesium bromide diethyl etherate (MgBr(2).Et(2)O)] produced a mixture of the intermediate 3-hydroxy-3-cyanopropenoporphyrin, the corresponding trimethylsilyl ether derivative, and the unexpected propenochlorins. The yields of the reaction products were found to depend on the reaction conditions and the catalysts used. The intermediate porphyrins on treatment with concentrated sulfuric acid yielded the free-base cyanobenzochlorins in major quantity along with several other novel benzochlorins as minor products. Reduction of ethyl-3-hydroxy-1-pentenoate-porphyrin with DIBAL-H/NaBH(4) and subsequent acid treatment provided the corresponding free-base 10(3)-(2-hydroxyethyl)benzochlorin, which upon a sequence of reactions gave a free-base benzochlorin bearing a carboxylic acid functionality in good yield. It was then condensed with a variety of carbohydrates (glucosamine, galactosamine, and lactosamine), and the related conjugates were screened using the galectin-binding-ability assay. Among the carbohydrate conjugates investigated, the lactose and galactose analogues displayed the galectin-binding ability with an enhancement of about 300-400-fold compared to lactose. In preliminary studies, all photosensitizers (with or without carbohydrate moieties) were found to be active in vitro [radiation-induced fibrosarcoma (RIF) tumor cells]. However, the cells incubated with lactose (known to bind to beta-galactoside-recognized proteins) prior to the addition of the photosensitizers containing the beta-galactose moiety (e.g., galactose and lactose) produced a 100% decrease in their photosensitizing efficacy. Under similar experimental conditions, benzochlorin without a beta-galactoside moiety or the related glucose conjugate did not show any inhibition in its photosensitizing efficacy. These results in combination with the galectin-binding data indicate a possible beta-galactoside-recognized protein specificity of the galactose- and lactose-benzochlorin conjugates. 相似文献
75.
Tong Ren Steven Radak Yuhua Ni Guolin Xu Chun Lin Kelly L. Shaffer Veronica DeSilva 《Journal of chemical crystallography》2002,32(7):197-203
Crystal structures of four diphenylformamidines bearing phenyl substituents ortho-CH3O (1), ortho-C2H5O (2), meta-CH3O (3), and meta-
n
BuO (4) are reported. In each of the structures, formamidine exists as an unsymmetrical cyclic hydrogen bond dimer, and the geometry of the amidine unit is consistent with the localized C–N and C=N bonds. Interesting conformations due to the orientation of aryl groups were also observed. Crystal Data: 1, orthorhombic, Pbca, a = 11.297(1) Å, b = 15.092(1) Å, c = 16.380(2) Å, V = 2792.6(4) Å3, Z = 8; 2, triclinic, P
, a = 9.651(1) Å, b = 11.974(1) Å, c = 14.583(2) Å, = 101.789(2)°, = 99.320(2)°, = 99.048(2)°, V = 1595.9(3) Å3, Z = 4; 3, orthorhombic, Pbca, a = 15.562(2) Å, b = 8.626(1) Å, c = 20.110(2) Å, V = 2699.4(5) Å3, Z = 8; 4, monoclinic, P21/c, a = 14.525(2) Å, b = 15.534(2) Å, c = 8.818(1) Å, = 93.113(2)°, V = 1986.6(4) Å3, Z = 4. 相似文献
76.
采用固相亚磷酸三酯法和化学与酶促相结合的方法合成了9个PstI接头片段,并对它们进行了酶切反应研究.结果表明:PstI识别序列中尿苷的存在只降低其互补链的切割程度,对其本链没有影响;PstI切割底物是按两步单股切割机制进行,作用的最小底物是含有识别序列的8~12聚脱氧核糖核苷酸,且对底物中识别序列两边的碱基对数目有一定要求;PstI识别序列中的二个胞苷在酶反应中起的作用是不一样的 相似文献
77.
铜离子与黄酮类配合物的促氧化作用 总被引:1,自引:0,他引:1
本文研究了3种结构相关的黄酮类化合物:黄芩素(Baicalein)、黄芩苷(Baicalin)和汉黄芩素(Wogonin)与Cu2 的配位作用,考察了其络合金属离子的结构特征,并且检测了黄酮类化合物与Cu2 形成配合物后的促氧化活性.用紫外分光光度法扫描黄酮类化合物与Cu2 形成配位后的吸光曲线变化;用电泳法检测了黄酮类化合物与Cu2 形成配合物后对DNA链的氧化损伤.结果表明,这3种黄酮主要是通过A环鳌合Cu2 .黄芩素和汉黄芩素与Cu2 形成配合物后不具有促氧化作用,而黄芩苷与Cu2 形成配合物后仍然具有一定的促氧化作用,能够导致DNA的氧化损伤. 相似文献
78.
Dobhal MP Li G Gryshuk A Graham A Bhatanager AK Khaja SD Joshi YC Sharma MC Oseroff A Pandey RK 《The Journal of organic chemistry》2004,69(19):6165-6172
Plumieride was isolated as one of the major components from the biologically active methanolic extract of the bark of Plumeria bicolor (family Apocynaceae). For investigating the effect of substituents on cytotoxic activity it was modified into a series of compounds. Replacing the methyl ester functionality of plumieride with alkyl amides of variable carbon units improved the cytotoxic activity, and a correlation between overall lipophilicity and cytotoxic activity was observed. In plumieride, the glucose moiety was converted into a di- and trisaccharide by following the protection and deprotection approach, and the resulting compounds produced enhanced cytotoxicity. However, these compounds were found to be less effective than plumeiride containing a dodecyl (12 carbon units) amide group. Among all of the derivatives, the naturally occurring plumieride showed the least cytotoxicity (50% cell kill = 49.5 microg/mL), and the dodecyl amide analogue of plumieridepentaacetate produced the best efficacy (50% cell kill = 11.8 microg/mL). The di- and trisaccharide analogues were found to be slightly less effective than the dodecyl derivative (50% cell kill = 15-17 microg/mL). The in vitro cytotoxicity of the plumieride analogues was determined in radiation-induced fibrosarcoma (RIF) tumor cells. 相似文献
79.
80.
在对常德—张家界高速公路慈利东互通段工程地质综合测试、补充勘探的基础上 ,通过对膨胀土及其改良土进行了系统的试验研究 ,如自由膨胀率、有荷膨胀量、收缩、胀缩总率、颗粒分析、压缩、抗剪强度、承载比试验 ,评价了该段膨胀土的工程特性 ,对于指导膨胀土路基的设计与施工 ,具有重要的意义 相似文献