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91.
Hiraoka K Ninomiya S Chen LC Iwama T Mandal MK Suzuki H Ariyada O Furuya H Takekawa K 《The Analyst》2011,136(6):1210-1215
This paper deals with the dielectric barrier discharge (DBD) ion source composed of the outer cylindrical dielectric tube and the inner grounded metallic tube electrode. The sample gas is supplied through the inner ceramic tube. In this ion source, the DBD plasma is localized in the DBD tube so that the sample gases can be ionized just outside of the ceramic tube by the DBD excited helium gas without being exposed in the plasma jet. Besides, ambient air does not take part in the ionization of the sample vapor because ionization takes place inside the DBD ion source. Thus, this method is totally free from contaminants in ambient air. It was found that this ion source is capable of soft, high-sensitivity, and reproducible ionization. Application of this technique to the analysis of methamphetamine, carbaryl and basil leaf was given. 相似文献
92.
Kuma S Nakahara H Tsubouchi M Takahashi A Mustafa M Sim G Momose T Vilesov AF 《The journal of physical chemistry. A》2011,115(25):7392-7399
Clusters of tetracene molecules with different numbers of attached (Ar)(N), (Ne)(N) and (H(2))(N) particles (N = 1-2000) are assembled inside superfluid He nanodroplets and studied via laser-induced fluorescence. The frequency shift of the fluorescence spectrum of the tetracene molecules is studied as a function of cluster size and pickup order of tetracene and cluster species. For (Ar)(N) and (Ne)(N) clusters, our results indicate that the tetracene molecules reside inside the clusters when tetracene is captured by the He nanodroplet before the cluster species; conversely, the tetracene molecules stay on the surface of the clusters when tetracene is captured after the cluster species. In the case of (H(2))(N) clusters, however, tetracene molecules reside inside the (H(2))(N) clusters irrespective of the pickup order. We conclude that (Ar)(N) and (Ne)(N) clusters are rigid at T = 0.38 K, while (H(2))(N) clusters of up to N = 2000 remain fluxional at the same temperature. The results may also indicate the occurrence of heterogeneous nucleation of the (H(2))(N) clusters, which is induced by the interaction with tetracene chromophore molecules. 相似文献
93.
Hyotanishi M Isomura Y Yamamoto H Kawasaki H Obora Y 《Chemical communications (Cambridge, England)》2011,47(20):5750-5752
Surfactant-free Pd nanoclusters (Pd NCs) (size: 1-1.5 nm) showed high catalytic activity in the Suzuki-Miyaura cross-coupling and Mizoroki-Heck reactions. The Pd NCs had a high turnover number, up to 6.0 × 10(8), which can be recycled at least five times without loss of catalytic activity. 相似文献
94.
Kidera M Seto Y Takahashi K Enomoto S Kishi S Makita M Nagamatsu T Tanaka T Toda M 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2011,78(3):1215-1219
We developed a detection technology for vapor forms of chemical warfare agents (CWAs) with an element analysis system using an electron cyclotron resonance ion source. After the vapor sample was introduced directly into the ion source, the molecular material was decomposed into elements using electron cyclotron resonance plasma and ionized. The following CWAs and stimulants were examined: diisopropyl fluorophosphonate (DFP), 2-chloroethylethylsulfide (2CEES), cyanogen chloride (CNCl), and hydrogen cyanide (HCN). The type of chemical warfare agents, specifically, whether it was a nerve agent, blister agent, blood agent, or choking agent, could be determined by measuring the quantities of the monatomic ions or CN(+) using mass spectrometry. It was possible to detect gaseous CWAs that could not be detected by a conventional mass spectrometer. The distribution of electron temperature in the plasma could be closely controlled by adjusting the input power of the microwaves used to generate the electron cyclotron resonance plasma, and the target compounds could be detected as molecular ions or fragment ions, enabling identification of the target agents. 相似文献
95.
Enomoto T Kanematsu S Tsunashima K Matsumoto K Hagiwara R 《Physical chemistry chemical physics : PCCP》2011,13(27):12536-12544
Fluorohydrogenate salts of quaternary phosphonium cations with alkyl and methoxy groups (tetraethylphosphonium (P(2222)(+)), triethyl-n-pentylphosphonium (P(2225)(+)), triethyl-n-octylphosphonium (P(2228)(+)), and triethylmethoxymethylphosphonium (P(222(101))(+))) have been synthesized by the metatheses of anhydrous hydrogen fluoride and the corresponding phosphonium bromide or chloride precursors. The three salts with asymmetric cations, P(222m)(FH)(2.1)F (m = 5, 8, and 101), are room temperature ionic liquids (ILs) and are characterized by differential scanning calorimetry, density, viscosity, and conductivity measurements. Linear sweep voltammetry using a glassy carbon working electrode shows these phosphonium fluorohydrogenate ILs have wide electrochemical windows (>4.9 V) with the lowest viscosity and highest conductivity in the known phosphonium-based ILs. Thermogravimetry shows their thermal stabilities are also improved compared to previously reported alkylammonium cation-based fluorohydrogenate salts. Differential scanning calorimetry and X-ray diffraction revealed that tetraethylphosphonium fluorohydrogenate salt, P(2222)(FH)(2)F, exhibits two plastic crystal phases. The high temperature phase has a hexagonal lattice, which is the first example of a plastic crystal phase with an inverse nickel arsenide-type structure, and the low-temperature phase has an orthorhombic lattice. The high-temperature plastic crystal phase exhibits a conductivity of 5 mS cm(-1) at 50 °C, which is the highest value for the neat plastic crystals. 相似文献
96.
It was found that (2 + 2) cycloaddition reaction of diketene with Schiff bases was effectively promoted by imidazole as a catalyst to afford 3-acetyl-2-azetidinone derivatives 4. As an application of this new method, a practical asymmetric synthesis of 4 and its conversion into (3S,4S)-4-carboxy-1-(di-p-anisylmethyl)-3-[(R)-1-hydroxyethyl]-2- azetidinone, which is a key intermediate for the synthesis of carbapenem and penem antibiotics, were accomplished. 相似文献
97.
Haruko Ikeuchi Kaoru Naganuma Marie Ichikawa Hiromichi Ozawa Tomoya Ino Makoto Sato Hiroko Yonezawa Sonomi Mukaida Akihiro Yamamoto Takeshi Hashimoto 《Journal of solution chemistry》2007,36(10):1243-1259
The diffusion coefficients of several tris(β-diketonato) ruthenium complexes in acetonitrile solutions containing a supporting electrolyte were determined by chronoamperometry.
The diffusion coefficients of the charged complexes, which were produced by electrochemical oxidation or reduction, were also
determined by double potential step chronoamperometry. Two kinds of radii of the complexes were evaluated. One was the Van
der Waals radius and the other was the geometric distance from the center of the complex to the outer surface of the farthest
atom. The latter quantity was determined from X-ray diffractometric data. The diffusion coefficients of the neutral complexes
were discussed on the basis of the Stokes-Einstein equation. Those of charged complexes could not be explained by the theoretical
equation presented by Hubbard and Onsager. 相似文献
98.
Kotaro Ishiji Tomoyuki Matsuda Hiroko Tokoro Toshiaki Iwazumi Shin-ichi Ohkoshi 《Journal of Physics and Chemistry of Solids》2007,68(11):2158-2161
Cesium manganese hexacyanoferrates exhibit an interesting phenomenon of temperature-induced phase transition accompanied by a variation in the magnetic susceptibility. We observed the variation in the electronic state of Mn during the phase transition by using X-ray absorption spectroscopy. The results of the analyses showed that the content ratio of FeII-CN-MnIII and FeIII-CN-MnII systematically varied during the phase transition. However, the ratio of FeII-CN-MnII remained constant at almost all temperatures. These results suggest that the charge transfer between Fe and Mn ions in the FeIII-CN-MnII or the FeII-CN-MnIII bond produces the phase transition. 相似文献
99.
Summary We consider the stationary Navier-Stokes equations in a certain type of semi-infinite channel under the general outflow condition.
Assuming that the domain and the data are symmetric with respect to a straight line, the axis of symmetry, and that the axis
intersects every component of the boundary, we show the existence of solutions and certain regularity properties of the solutions.
Sunto In questo lavoro consideriamo le equazioni di Navier-Stokes stazionarie in un certo tipo di canali semi-infiniti sotto la condizione generale di outflow. Assumendo che sia il dominio sia i dati siano simmetrici rispetto ad una retta, l’asse di simmetria, e che questa retta intersechi ogni componente del bordo, mostriamo esistenza di soluzioni ed alcune proprietà di regolarità delle stesse.相似文献
100.
A new type of dynamic light scattering method for the size measurement of nanoparticles was developed using a transmission grating. A sample cell was located behind the grating, and light was incident from the grating side. The scattered light by a solution with nanopariticles was mixed with diffracted light by the grating, and the mixed signal was detected; namely, the diffracted light was used as reference light for heterodyne detection. It was confirmed that the S/N ratio of the autocorrelation curve was 26-times improved by heterodyne detection. Furthermore, the S/N ratio was improved by setting the sample cell at the sample grating distance where the electromagnetic field is maximum due to the Talbot effect. Size measurements for several kinds of nanoparticles were demonstrated by this new method. 相似文献