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571.
Hayashi Y Yamaguchi J Sumiya T Hibino K Shoji M 《The Journal of organic chemistry》2004,69(18):5966-5973
The direct proline-catalyzed asymmetric alpha-aminoxylation of aldehydes and ketones has been developed using nitrosobenzene as an oxygen source, affording alpha-anilinoxy-aldehydes and -ketones with excellent enantioselectivity. Reaction conditions have been optimized, and low temperature (-20 degrees C) was found to be a key for the successful alpha-aminoxylation of aldehydes, while slow addition of nitrosobenzene is essential for that of ketones. The scope of the reaction is presented. 相似文献
572.
Kumemura T Choshi T Hirata A Sera M Takahashi Y Nobuhiro J Hibino S 《Chemical & pharmaceutical bulletin》2005,53(4):393-397
A total synthesis of a new furo[3,2-h]isoquinoline alkaloid TMC120-B (2), isolated from Aspergillus ustus together with two related compounds, has been completed in sixteen steps. The key step is the synthesis of the appropriate 3,7,8-trisubstituted isoquinoline framework (23) based on a thermal electrocyclic reaction of the 1-aza 6pi-electron system involving the benzene double bond. In addition, the microwave assisted electrocyclic reaction of this system was newly performed. 相似文献
573.
A highly heterogeneous glycoprotein, alpha1-acid glycoprotein, was resolved into their glycoforms by capillary electrophoresis using a surface-modified capillary in 20 mM acetate buffer (pH 4.2) containing 0.5% (w/v) hydroxypropylmethylcellulose. We collected the fractions containing each glycoform as nearly pure state by capillary electrophoresis, and examined the molecular masses of these glycoforms by matrix assisted laser desorption time-of-flight mass spectrometry. We also analyzed carbohydrate chains after releasing them with N-glycosidase F followed by fluorescent labeling with 8-aminopyrene-1,3,6-trisulfonate. We found that the separation of glycoforms was mostly due to the presence of multiantennary carbohydrate chains. We propose that the present technique is useful for the analysis of post translational modification of proteins with carbohydrate chains. 相似文献
574.
The pressure-induced phase transition in a microemulsion, consisting of pentaethylene glycol mono-n-dodecyl ether, water, and n-octane, was investigated by means of small-angle neutron scattering. A pressure-induced phase transition from a lamellar structure to a hexagonal structure was observed. The temperature-pressure phase boundary shows a positive slope with dTdP approximately 0.09 KMPa. The structure unit of the high-pressure hexagonal phase was an oil-in-water cylinder with the membrane thickness of 15.5 A, identical to the low-temperature hexagonal phase. Pressurizing was found to have the same effect by decreasing temperature. This behavior was satisfactorily explained with the pressure dependence of the spontaneous curvature of surfactant membranes. That is, the volume change of surfactant tails plays a dominant role in the structure change of the microemulsion with applying pressure. 相似文献
575.
Fumika Karaki Miki Kuwada Saki Tajiri Misaki Kanda Mari Yanai Mitsuhiro Kamimura 《合成通讯》2019,49(2):212-220
Protecting groups are indispensable in organic synthesis and there is a great need for a variety of deprotection methods. Here, we investigated the scope of the application of a deprotection procedure using SO3H silica gel, which we have previously reported as a desilylation procedure. Under these conditions, -OMOM, -OSEM, -OTHP, and -OAc groups and dimethyl acetal were cleaved. Pivaloyloxy, benzyloxy and methoxy carbonyl groups remained intact and selective deprotection of TBS groups in the presence of other protecting groups was accomplished. We succeeded in cleaving an acetyl group on a secondary alcohol in a highly polar nortropine derivative. Our findings here provide another deprotection option and would be helpful in the synthesis of multifunctional compounds. 相似文献
576.
Amenomori M Cao Z Ding LK Feng ZY Hibino K Hotta N Huang Q Huo AX Jia HY Jiang GZ Jiao SQ Kajino F Kasahara K Labaciren Mei DM Meng L Meng XR Mimaciren Mizutani K Mu J Nanjo H Nishizawa M Nusang Oguro A Ohnishi M Ohta I Ren JR Saito T Sakata M Shi ZZ Shibata M Shirai T Sugimoto H Sun XX Tai A Taira K Tan YH Tateyama N Torii S Wang H Wen CZ Yamamoto Y Yao XY Yu GC Yuan P Yuda T Zeng JG Zhang CS Zhang HM Zhang L Zhasang Zhaxiciren Zhou WD 《Physical review letters》1992,69(17):2468-2471
577.
Wada M Inoue K Thara A Kishikawa N Nakashima K Kuroda N 《Journal of chromatography. A》2003,990(1-2):189-195
A combination of the electrophoretically mediated microanalysis methodology with a partial filling technique was applied for the inhibition study of bovine liver rhodanese by 2-oxoglutarate. In this set-up, part of the capillary is filled with the best buffer for the enzymatic reaction, while the rest of the capillary is filled with the optimal background electrolyte for separation of substrates and products. The estimated value of KI for 2-oxoglutarate was 3.62·10−4±1.43·10−4 M with respect to cyanide and 1.40·10−3±1.60·10−4 M with respect to thiosulfate. In addition, the type of inhibition was also evaluated. The findings of 2-oxoglutarate as the competitive inhibitor with respect to cyanide and as the uncompetitive inhibitor with respect to thiosulfate are in accordance with previous literature data. 相似文献
578.
Tobe M Isobe Y Tomizawa H Nagasaki T Obara F Matsumoto M Hayashi H 《Chemical & pharmaceutical bulletin》2002,50(8):1073-1080
We synthesized various 6-nitroquinazolines by modifying the structure of compound 1 and evaluated their inhibitory activities toward both TNF-alpha production and T cell proliferation responses. The presence of the unsubstituted piperazine ring at the C(7)-position was required for both inhibitory activities. In this series of compounds, 5d and 5f, containing the 4-fluorophenyl and 3,4-difluorophenyl moiety, respectively, at the C(4)-position, showed the suppressing effects toward both responses with low cell growth inhibition. Furthermore, the oral administration of these compounds mentioned above at doses of 30 and 100 mg/kg also resulted in significant inhibition of TNF-alpha production induced by LPS in vivo. 相似文献
579.
Noboru Morita Mitsuhiro Kurita Koichi Saito Maki Kinjo Shunji Ito Toyonobu Asao Masako Ueno Toshio Sato Akio Tajiri Masafumi Yasunami 《Journal of organometallic chemistry》1998,570(2):3223
The reactivities of tricarbonyl(2,4-cycloheptadiene-1,6-dione)iron toward several kinds of nucleophiles and electrophiles were investigated. As a result, it was found that tricarbonyl(2,4-cycloheptadiene-1,6-dione)iron has several reaction sites and undergoes several types of reactions. A new synthetic route to hinokitiol and tricarbonyl-(7,8-diphenylheptariafulvalene-1,6-quinone)iron from (2,4-cycloheptadiene-1,6-dione)iron was explored. 相似文献
580.
Mitsuhiro Yamashita Masa-Aki Kakimoto Yoshio Imai 《Journal of polymer science. Part A, Polymer chemistry》1993,31(6):1513-1518
A new triphenylphosphine-type monomer, bis(4-aminophenyl) phenylphosphine, was synthesized starting from p-bromoaniline and dichlorophenylphosphine. The aromatic polyamides (aramids) containing triphenyphosphine unit in the polymer backbone was prepared by the polycondensation of this diamine with various aromatic diacid chlorides using a low-temperature solution method in N,N-dimethylacetamide (DMAc). The aramids having inherent viscosities of 0.4–0.7 dL/g were obtained in quantitative yields. The polymers were amorphous and soluble in various organic solvents such as DMAc, N-methylpyrrolidone, dimethyl sulfoxide, pyridine, and m-cresol. Transparent, tough, and flexible films were obtained by casting from the DMAc solutions. The glass transition temperatures of the aramids were in the range of 265–310°C, and the 10% weight loss temperatures were above 400°C in air. © 1993 John Wiley & Sons, Inc. 相似文献