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191.
Cai RG 《Physical review D: Particles and fields》1996,53(8):4680-4683
192.
Behforouz M Haddad J Cai W Arnold MB Mohammadi F Sousa AC Horn MA 《The Journal of organic chemistry》1996,61(19):6552-6555
The novel 7-(N-formyl-, 7-(N-acetyl-, and 7-(N-isobutyrylamino)-2-methylquinoline-5,8-diones were synthesized in excellent overall yields in three steps via the nitration of the commercially available 8-hydroxy-2-methylquinoline followed by a reduction-acylation step and then oxidation. Acid hydrolysis of 7-(N-acetylamino)-2-methylquinoline-5,8-dione (14a) afforded the novel 7-aminoquinoline-5,8-dione 7 in excellent yields. Due to our efficient preparation of dione 14a, we now report a short and practical method for the total synthesis of the potent antitumor agent lavendamycin methyl ester (1b) with an excellent overall yield. 相似文献
193.
Adamovich MI Aggarwal MM Alexandrov YA Andreeva NP Anson ZV Arora R Avetyan FA Badyal SK Basova E Bazarov IK Bhalla KB Bhasin A Bhatia VS Bogdanov VG Bubnov VI Burnett TH Cai X Carshiev DA Chasnicov IY Chernova LP Chernyavski MM Eligbaeva GZ Eremenko LE Gaitinov AS Ganssauge ER Garpman S Gerassimov SG Grote JG Gulamov KG Gupta SK Gupta VK Heckman HH Huang H Jacobsson B Judek B Kachroo S Kalyachkina GS Kanygina EK Karabova M Kharlamov SP Kitroo S Koss T Krasnov SA Kumar V Lal P Larionova VG 《Physical review D: Particles and fields》1993,47(9):3726-3732
194.
195.
The self-assembled monolayer structure of the products of elaidic acid iodination (the racemic mixture of 9,10-(9S,10R)-diiodooctadecanoic acid and 9,10-(9R,10S)-diiodooctadecanoic acid) and the products of oleic acid iodination (the racemic mixture of 9,10-(9R,10R)-diiodooctadecanoic acid and 9,10-(9S,10S)-diiodooctadecanoic acid) are studied by high-resolution scanning tunneling microscopy. For the iodination products of elaidic acid, the separation of enantiomers into distinct chiral domains during the formation of the 2-D crystal on the highly ordered pyrolytic graphite (HOPG) surface is not observed. Instead, within the diiodooctadecanoic acid SAM, each row of molecules is composed of opposite racemates. The two opposite racemates pack alternately inside a row, using different faces to adsorb on the surface. The unit cell is composed of a pair of opposite racemates, forming a heterochiral structure. For the iodination products of oleic acid, the racemic mixture is observed to exhibit quasi-phase separation during the formation of the 2-D crystal on the HOPG surface. Each row is composed of homochiral acid molecules, either the 9,10-(9R,10R)-diiodooctadecanoic acid (R) or the 9,10-(9S,10S)-diiodooctadecanoic acid (S). The R row and the S row pack alternately, with a unit cell composed of four molecules. Two of the molecules in the unit cell are the 9,10-(9R,10R)-diiodooctadecanoic acid (R) molecules; two are the 9,10-(9S,10S)-diiodooctadecanoic acid (S) molecules. In the unit cell, the two molecules that have the same chirality pack antiparallel inside the homochiral row, using different faces to adsorb on the surface. These results suggest that several different types of chiral assembly are possible. Enantiomers with opposite chirality exhibit many chiral assembly patterns, forming heterochiral structures on the surface in addition to separation to form macroscopic chiral domains. By using different conformations, similar enantiomers with opposite chirality will display many chiral assembly patterns to form heterochiral structures on the surface. 相似文献
196.
Cai H Chen T Wang X Schultz AJ Koetzle TF Xue Z 《Chemical communications (Cambridge, England)》2002,(3):230-231
Reactions of Ta(NMe2)5 with D2SiR'Ph (R' = Me, Ph) were found to give a dideuteride eta 2-imine complex (Me2N)3Ta(mu-D)2(mu-N-eta 2-N,C-CH2NMe)Ta(NMe2)3(1-d2) through C-H activation of an amide ligand via beta-H abstraction, and the structure of 1 was confirmed by single crystal neutron and X-ray diffraction. 相似文献
197.
Xiufang Xu Yumei Xing Xia Yang Guichang Wang Zunsheng Cai Zhenfeng Shang Yinming Pan Xuezhuang Zhao 《International journal of quantum chemistry》2005,101(2):160-168
A total of eight possible isomers of C50O, an oxide of fullerene C50 (D5h), have been investigated by B3LYP/3‐21G calculations. The isomer, which has an annulene‐like structure with oxygen bridging across a [5,6] type C? C bond at the site between the pole and the equatorial belt, is found being the ground state of C50O. Four isomers are relatively more stable and the energy differences between them are not large. This result indicates that more than one C50O isomer will coexist once C50O is synthesized. The relative stabilities of the C50O isomers may be determined mainly by the strain release and by the formation of the cyclic phenylene substructure at the equatorial belt of the cage. The calculated nucleus independent chemical shifts (NICS) of the C50O isomers will be useful because from them one can expect outstanding NMR properties that can lead to their identification and characterization. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2005 相似文献
198.
Xiaohong Cai 《Journal of fluorine chemistry》2005,126(4):477-480
A general synthesis of 2-fluoro-1-naphthols in two steps from 1-indanones is reported. The 1-indanones are first converted to difluoromethyl 2-fluoro-1-napthyl ethers by reaction with difluorocarbene source, trimethylsilyl 2-fluorosulfonyl-2,2-difluoroacetate (TFDA). These ethers are then converted in high yield to the respective naphthols by heating with a mixture of acetic acid and 48% HBr. 相似文献
199.
200.
The adsorption and photocatalutic decomposition of citric acid on both Pt/TiO2 powder and n-TiO2 single crystal electrode were studied in aqueous solutions of various pH. It was found that citrate ions were chemisorbed on TiO2, which could increase the interfacial capacity and the filling factor of photocurrent-potential curves. The quantity of adsorption, slope of mott-Shottky plot and the rate of photocatalytic decomposition of citric acid were found to depend strongly on pH of solution. The phot ocatalytic decomposition of citric acid was discussed in light of its adsorption on TiO2. 相似文献