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941.
To synthesize sulfur-containing π-conjugated polymers, reaction conditions for rhodium-catalyzed hydrothiolation of terminal alkynes with arenethiols are optimized in detail. Under the optimized conditions, rhodium-catalyzed hydrothiolation of terminal alkynes proceeds regio- and stereoselectively to afford the corresponding vinyl sulfides via an anti-Markovnikov and syn-addition process. Then, the rhodium-catalyzed hydrothiolation is applied to polymerization of 2,5-diethynylthiophene with benzene-1,4-dithiol, which successfully provides sulfur-containing π-conjugated polymers with excellent regio- and stereoselectivities. 相似文献
942.
943.
Jin-Feng Kenji Aramaki Akihiro Ogawa Masahiko Tsukahara Hironobu Kunieda 《Journal of Dispersion Science and Technology》2013,34(1-3):29-36
Sodium (3-dodecanoyloxy-2-hydroxy-propyl) succinate (SLGMS) forms microemulsions by mixing with cosurfactants such as glycerol mono(2-ethylhexyl) ether (MEH), although the combination with ordinary cosurfactant such as hexanol does not form a microemulsion of large solubilization. The middle-phase microemulsion coexists with excess water and oil (octane) phases at an optimum-mixing fraction of SLGMS and MEH in the presence of salt. The monomeric solubility of MEH in oil is low and MEH is mainly combined with SLGMS at an oil—water interface inside microemulsions. With decreasing salinity, the three-phase body shrinks and eventually disappears. The three-phase body may be terminated at a tricritical point, at which three phases simultaneously coexist. The effect of type of oil on the solubilization capacity of the microemulsions is also discussed. 相似文献
944.
Yuji Ishii Shinji Takasu Ken Kuroda Kohei Matsushita Aki Kijima Takehiko Nohmi Kumiko Ogawa Takashi Umemura 《Analytical and bioanalytical chemistry》2014,406(9-10):2467-2475
DNA adductome analysis using liquid chromatography–tandem mass spectrometry is a promising tool to exhaustively search DNA modifications. Given that the molecular weight of chemical-specific adducts is determined by the total molecular weights of the active form and nucleotide bases, we developed a new method of comprehensive analysis for chemical-specific DNA adducts based on the principle of adductome analysis. The actual analytical mass range was 50 mass units up or down from the average molecular weight of the four DNA bases plus the molecular weight of the expected active form of the chemical. Using lucidin-3-O-primeveroside (LuP), lucidin-modified bases formed by its active form were exhaustively searched using this new method. Various DNA adducts, including Luc-N 2-dG and Luc-N 6-dA, were identified in the kidneys of rats given LuP. Together with measurement of 8-hydroxydeoxyguanosine (8-OHdG) levels, the combined application of this new method with a reporter gene mutation assay was performed to clarify renal carcinogenesis induced by madder color (MC) that includes LuP and alizarin (Alz) as constituent agents. A DNA adductome map derived from MC-treated rats was almost identical to that of LuP-treated rats, but not Alz-treated rats. Although 8-OHdG levels were elevated in MC- and Alz-treated rats, significant increases in gpt and Spi? mutant frequencies were observed only in MC- and LuP-treated rats. In addition, the spectrum of gpt mutants in MC-treated rats showed almost the same pattern as those in LuP-treated rats. The overall data suggest that LuP may be responsible for MC-induced carcinogenicity and that the proposed methodology is appropriate for exploring and understanding mechanisms of chemical carcinogenesis. Figure
DNA adductome map of kidneys from F344 gpt delta rats in the control and LuP-treated groups. The peaks detected in control and LuP-treated rats are represented as black and blue spots, respectively 相似文献
945.
Shoujiro Ogawa Satoshi Ooki Kenta Shinoda Tatsuya Higashi 《Analytical and bioanalytical chemistry》2014,406(26):6647-6654
The determination of the urinary vitamin D3 metabolites might prove helpful in the assessment of the vitamin D status. We developed a method for the determination of trace vitamin D3 metabolites, 25-hydroxyvitamin D3 [25(OH)D3] and 24,25-dihydroxyvitamin D3 [24,25(OH)2D3], in urine using liquid chromatography/electrospray ionization-tandem mass spectrometry (LC/ESI-MS/MS) combined with derivatization using an ESI-enhancing reagent, 4-(4′-dimethylaminophenyl)-1,2,4-triazoline-3,5-dione (DAPTAD), and its isotope-coded analogue, 2H4-DAPTAD (d-DAPTAD). The urine samples were treated with β-glucuronidase, purified with an Oasis® hydrophilic–lipophilic balanced (HLB) cartridge, and then subjected to the derivatization. The DAPTAD derivatization enabled the highly sensitive detection (detection limit, 0.25 fmol on the column), and the use of d-DAPTAD significantly improved the assay precision [the intra- (n?=?5) and inter-assay (n?=?3) relative standard deviations did not exceed 9.5 %]. The method was successfully applied to urine sample analyses and detected the increases of the urinary 25(OH)D3 and 24,25(OH)2D3 levels due to vitamin D3 administration. Graphical Abstract
946.
Keiji Yoshimura Ryoei Kikuchi Takashi Kimoto Toru Ozeki Kazuhiko Imano Masahiro Kajikawa Nobuaki Ogawa 《Analytical sciences》2006,22(6):845-848
Fog droplets in the atmosphere are first produced by the activation of cloud condensation nuclei (CCN), which are originally some ionic compound. Subsequently, the nuclei grow by vapor diffusion. Fog droplets are polluted through the activation process and successive diffusion growth and residence (post activation). We cannot distinguish the effects of the two pollution processes of natural fog water samples. We found that fog droplets can be produced artificially without CCN using an ultrasonic humidifier. Because the artificial fog droplets are not polluted by CCN, the movement of the fog droplets in natural air will take up some pollutants in the air. Consequently, the two pollution processes of fog (the activation of CCN and the post activation process) can be discriminated using data from field experiments. This sampling analytical method is extremely important for further research regarding fog, clouds and environmental chemistry. 相似文献
947.
The extraction behaviors of bismuth(III) with carboxylic acid (HL), which have not yet been clearly elucidated, because of the precipitation of hydroxide, were studied using the 2-bromoalkanoic acid in benzene and in hexane systems under aqueous conditions of high acidity at I = 1.0 M ((H,Li)NO3). The extraction equilibria were analyzed based on the-initial concentration of nitric acid and the concentration of bismuth(III) extracted in the organic phase. The extracted species and the logarithmic values of the extraction constant (log Kex) were found to be a single species of BiL3(HL)3 for the systems of 2-bromooctanoic acid/benzene (log Kex = -1.66) and 2-bromohexadecanoic acid/benzene (-1.58), and to be two species of BiL3(HL)4 (-1.01) and Bi3L9HL (-1.62) for the system of 2-bromooctanoic acid/hexane, where the monomer was dominant at a higher reagent concentration. 相似文献
948.
The hydrogen content in a-Si1−xGex:H thin films is an important factor deciding the density and the optical band gap. We measured the elemental depth profiles of hydrogen together with Si and Ge by elastic recoil detection analysis (ERDA) combined with Rutherford backscattering (RBS) using MeV He2+ ions. In order to determine the hydrogen depth profiles precisely, the energy- and angle-dependent recoil cross-sections were measured in advance for the standard sample of a CH3+-implanted Si substrate. The cross-sections obtained here are reproduced well by a simple expression based on the partial wave analysis assuming a square well potential (width: r0 = 2.67 × 10−13 cm, depth: V0 = −36.9 MeV) within 1%. For the a-Si1−xGex:H films whose elemental compositions were determined by ERDA/RBS, we measured the secondary ions yields of HCs2+, SiCs2+, H−, Si− and Ge− as a function of Ge concentration x. As a result, it is found that the useful yield ratios of HCs2+/SiCs2+, H−/Si− and Ge−/Si− are almost constant and thus the elemental depth profiles of the a-Si1−xGex:H films can be also determined by secondary ion mass spectrometry (SIMS) within 10% free from a matrix effect. 相似文献
949.
In the field of materials science, π-conjugated molecules bearing a group 16 heteroatom are of great importance. Sulfur or selenium containing porphyrins were successfully synthesized using the transition-metal-catalyzed reaction with diphenyl dichalcogenides. NMR studies indicated the preferential formation of the (Z)-isomer. 相似文献
950.
Received: 20 September 1998 相似文献