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101.
Tetsuya Tsuda Susumu Kuwabata Gery R. Stafford Charles L. Hussey 《Journal of Solid State Electrochemistry》2013,17(2):409-417
The electrochemistry of Hf(IV) and the electrodeposition of Al–Hf alloys were examined in the Lewis acidic 66.7–33.3 mol% aluminum chloride-1-ethyl-3-methylimidazolium chloride molten salt containing HfCl4. When cyclic staircase voltammetry was carried out at a platinum disk electrode in this melt, the deposition and stripping waves for Al shifted to negative and positive potentials, respectively, suggesting that aluminum stripping is more difficult due to the formation of Al–Hf alloys. Al–Hf alloy electrodeposits containing ~13 at.% Hf were obtained on Cu rotating wire and cylinder electrodes. The Hf content in the Al–Hf alloy deposits depended on the HfCl4 concentration in the melt, the electrodeposition temperature, and the applied current density. The deposits were composed of dense crystals and were completely chloride-free. The chloride-induced pitting corrosion potential of the resulting Al–Hf alloys was approximately +0.30 V against pure aluminum when the Hf content was above 10 at.%. 相似文献
102.
We have investigated the nonradiative deactivation process of malachite green in the singlet excited states, S(1) and S(2), by high-level ab initio quantum chemical calculations using the CASPT2//CASCF approach. The deactivation pathways connecting the Franck-Condon region and conical intersection regions are identified. The initial population in the S(1) state is on a flat surface and the relaxation involves a rotation of phenyl rings, which leads the molecule to reach the conical intersection between the S(1) and S(0) states, where it efficiently decays back to the ground state. There exists a small barrier connecting the Franck-Condon and conical intersection regions on the S(1) potential energy surface. The decay mechanism from the S(2) state also involves the twisting motion of phenyl rings. In contrast to the excitation to the S(1) state, the initial population is on a downhill ramp potential and the barrierless relaxation through the rotation of substituted phenyl rings is expected. During the course of relaxation, the molecule switches to the S(1) state at the conical intersection between S(2) and S(1), and then it decays back to the ground state through the intersection between S(1) and S(0). In relaxation from both S(1) and S(2), large distortion of phenyl rings is required for the ultrafast nonradiative decay to the ground state. 相似文献
103.
Shoji Kasahara Tetsuya Takine Yutaka Takahashi Toshiharu Hasegawa 《Queueing Systems》1993,14(3-4):349-367
Many researchers have studied variants of queueing systems with vacations. Most of them have dealt with M/G/1 systems and have explicitly analyzed some of their performance measures, such as queue length, waiting time, and so on. Recently, studies on queueing systems whose arrival processes are not Poissonian have appeared. We consider a single server queueing system with multiple vacations and E-limited service discipline, where messages arrive to the system according to a switched Poisson process. First, we consider the joint probability density functions of the queue length and the elapsed service time or the elapsed vacation time. We derive the equations for these pdf's, which include a finite number of unknown values. Using Rouché's theorem, we determine the values from boundary conditions. Finally, we derive the transform of the stationary queue length distribution explicitly. 相似文献
104.
Masanori Fujinami Satoshi Jinno Masafumi Fukuzumi Takumi Kawaguchi Koichi Oguma Takashi Akahane 《Analytical sciences》2008,24(1):73-79
A production method for a positron microprobe using a beta+-decay radioisotope (22Na) source has been investigated. When a magnetically guided positron beam was extracted from the magnetic field, the combination of an extraction coil and a magnetic lens enabled us to focus the positron beam by a factor of 10 and to achieve a high transport efficiency (71%). A 150-nm-thick Ni(100) thin film was mounted at the focal point of the magnetic lens and was used as a remoderator for brightness enhancement in a transmission geometry. The remoderated positrons were accelerated by an electrostatic lens and focused on the target by an objective magnetic lens. As a result, a 4-mm-diameter positron beam could be transformed into a microprobe of 60 microm or less with 4.2% total efficiency. The S parameter profile obtained by a single-line scan of a test specimen coincided well with the defect distribution. This technique for a positron microprobe is available to an accelerator-based high-intensity positron source and allows 3-dimensional vacancy-type defect analysis and a positron source for a transmission positron microscope. 相似文献
105.
Asakura H Teramura K Shishido T Tanaka T Yan N Xiao C Yao S Kou Y 《Physical chemistry chemical physics : PCCP》2012,14(9):2983-2990
A combination of in situ time-resolved DXAFS and ICP-MS techniques reveals that the formation process of Rh nanoparticles (NPs) from rhodium trichloride trihydrate (RhCl(3)·3H(2)O) in ethylene glycol with polyvinylpyrrolidone (PVP) at elevated temperature is a first-order reaction, which indicates that uniform size Rh NPs appear consecutively and these Rh NPs do not aggregate with each other. 相似文献
106.
Tetsuya Yamamoto 《Colloid and polymer science》2013,291(11):2741-2744
Methacrylic monomer was used in soap-free emulsion polymerization in order to obtain a stable dispersion containing particles of the polymerized monomer. 2,2′-Azobis(2-methylpropionitrile) (AIBN) or 1,1′-azobis(1-acetoxy-1-phenylethane) (OTAZO-15) were used as the radical initiator. Although particles with a size of about 1.0 μm were obtained when using methyl methacrylate as the monomer and AIBN as the initiator, the particles did not exhibit good dispersion stability. When OTAZO-15, which has phenyl rings, was used as the initiator, the monomer phase solidified instead of forming particles in the aqueous phase. Benzyl methacrylate (BMA) monomer, which contains a phenyl ring, was polymerized using AIBN. Negatively charged particles with a size of 0.90 μm were formed. These particles exhibited good dispersion stability probably because of the pi electrons of the phenyl ring in the BMA monomer. The method in this study allows the synthesis of nearly micron-sized particles without surfactant, organic solvent, and electrolyte. 相似文献
107.
The magnetic property of Co2B2O5 and the optical property of M2B2O5 (M = Mn, Co) were investigated. Co2B2O5 showed antiferromagnetic behavior below the Néel temperature of TN ≈ 45 K, and the Weiss temperature was TW = +7.7 K. The effective magnetic moment of Co was 4.96 μB, which indicated that Co was divalent and in a high-spin state. Absorptions attributed to the d–d transitions in Mn2+ and Co2+ ions were observed at 250–650 nm in the diffuse reflection spectra. The optical absorption edges of Mn2B2O5 and Co2B2O5 were at 243 nm (5.11 eV) and 299 nm (4.15 eV), respectively. 相似文献
108.
Multiple Reaction Pathways Operating in the Mechanism of Vinylogous Mannich‐Type Reaction Activated by a Water Molecule 下载免费PDF全文
A systematic search for reaction pathways for the vinylogous Mannich‐type reaction was performed by the artificial force induced reaction method. This reaction affords δ‐amino‐γ‐butenolide in one pot by mixing 2‐trimethylsiloxyfuran, imine, and water under solvent‐free conditions. Surprisingly, the search identified as many as five working pathways. Among them, two concertedly produce anti and syn isomers of the product. Another two give an intermediate, which is a regioisomer of the main product. This intermediate can undergo a retro‐Mannich reaction to give a pair of intermediates: an imine and 2‐furanol. The remaining pathway directly generates this intermediate pair. The imine and 2‐furanol easily react with each other to afford the product. Thus, all of these stepwise pathways finally converge to give the main product. The rate‐determining step of all five (two concerted and three stepwise) pathways have a common mechanism: concerted Si? O bond formation through the nucleophilic attack of a water molecule on the silicon atom followed by proton transfer from the water molecule to the imine. Therefore, these five pathways have comparable barriers and compete with each other. 相似文献
109.
110.
Yoshiki Chujo Tetsuya Nakamura Yuya Yamashita 《Journal of polymer science. Part A, Polymer chemistry》1990,28(1):59-65
Mercapto-16-crown-5 was prepared starting from tetraethyleneglycol and 3-chloro-2-chloromethyl-1-propene. Radical polymerization of methyl methacrylate was carried out in the presence of mercapto-16-crown-5 as a chain transfer agent to give crown ether-terminated poly(methyl methacrylate). The end crown group was characterized by IR and 1H-NMR spectra. Sodium cation was selectively extracted by this crown-containing polymer. The molecular weight of the obtained polymer had influence upon the ability of extraction of sodium cation. 相似文献