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121.
Using density functional theory methods, we have studied carbon trioxide, its adsorption and dissociation on Ag(100). In the gas phase, two isomers are found, D3h and C2v, with the latter of 2.0 kcal mol?1 lower in energy at the PW91PW91/6?31G(d) level. For CO3 on Ag(100), the calculated adsorption energy is 91.2 and 89.1 kcal mol?1 for the bi‐coord perpendicular and tri‐coord parallel structures, respectively. Upon the adsorption, 0.50 ~ 0.56 electron is transferred from silver to CO3, indicative of significant ionic characters of the adsorbate‐surface bonding. In addition, the geometry of CO3 is largely changed by its strong interaction with silver. For CO3(ad) → O(ad) + CO2(gas), the energy barrier is calculated to be 19.8 kcal mol?1 through the bi‐coord path. The process is endothermic with an enthalpy change of +17.3 ~ +26.7 kcal mol?1 and the weakly chemisorbed CO2 is identified as an intermediate on the potential energy surface. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2010 相似文献
122.
Chemoselective reduction of azides catalyzed by molybdenum xanthate by using phenylsilane as the hydride source 总被引:1,自引:0,他引:1
Mahagundappa R. Maddani 《Tetrahedron》2010,66(1):329-8551
A chemoselective, neutral, and efficient strategy for the reduction of azides to corresponding amines catalyzed by dioxobis(N,N,-diethyldithiocarbamato) molybdenum complex (1, MoO2[S2CNEt2]2) in the presence of phenylsilane is discovered. This chemoselective reduction strategy tolerates a variety of reducible functional groups. 相似文献
123.
Jonas Sävmarker 《Tetrahedron letters》2010,51(52):6886-6889
Stille-type carbonylative cross-couplings, employing palladium catalysis and Mo(CO)6 as the carbon monoxide carrier, were used for the preparation of deoxybenzoins. Straightforward transformations were conveniently performed in closed vessels at 100 °C, providing the products in good yields. Benzyl bromides and chlorides were used as coupling partners with aryl and heteroaryl stannanes. This mild three-component carbonylation employs the destabilizing agent DBU to promote smooth release of carbon monoxide from Mo(CO)6, which made this protocol operationally simple and minimized the formation of Stille diarylmethane products. 相似文献
124.
The novel tridentate chiral ligand 2,6-bis{[(1R,2S,4R)-2-hydroxy-1,3,3-trimethyl-bicyclo[2.2.1]hept-2-yl]}pyridine (1) was readily prepared by reaction of 2,6-dilithiopyridine with (R)-(−)-fenchone. Reaction of 1 with [MoO2(acac)2] resulted in the formation of the new metal-oxo five-coordinated complex [MoO2(ONO)] (2) [ONO = (1 – 2H)]. The reactivity of 2 has been studied and the derivatives [MoS2(ONO)] (3) and [MoO(O2)(ONO)] (4) were prepared. The compounds 1–4 have been characterised by 1H and 13C{1H} NMR, microanalysis and IR spectroscopy. Furthermore, the molecular structures of 1 and 2 have been determined by single-crystal X-ray diffraction. The behaviour of 2 as catalyst in oxotransfer and in nucleophilic substitution of propargylic alcohols reactions has been tested. 相似文献
125.
Jian Chen Prof. Shanghui Chen Dongyu Lu Weihong Zhang Fangyan Xie Weiguang Xie Dr. Li Gong Chengxin Wang Prof. 《Chemphyschem》2010,11(12):2546-2549
Raman spectroscopic analysis is performed on WO3 nanowires at room temperature at pressures from ambient conditions to 45 GPa. Linear dependence of the first‐order Raman signal on various high‐pressure (HP) sections is observed. Upon increasing the applied pressure, the WO3 nanowires undergo four phase transitions at pressures around 1.7, 4.6, 21.5, and 26.2 GPa, which are all less than that reported for bulk WO3. When the pressure is up to 42.5 GPa, a new high‐pressure phase (HP5) appears. This phase has never been reported and is not reversible while unloading the pressure. 相似文献
126.
A cellulose triacetate (CTA) membrane containing trioctylphosphine oxyde (TOPO) as carrier and 2-nitrophenyloctyl ether (NPOE) as a plasticizer was prepared. The membrane CTA + NPOE + TOPO was characterised using chemical techniques as well as Fourier Transform InfraRed (FTIR) spectroscopy, X-ray diffraction and Scanning Electron Microscopy (SEM). The CTA membrane is characterised by well-defined pores; these pores are completely filled with the NPOE and carrier. Surfaces of membranes with TOPO are smooth. The systems constituted by the mixture of CTA + NPOE, CTA + NPOE + TOPO do not give any diffraction. This can be due to the absence of crystallization within the membrane. On the other hand, this result should be attributable to the amorphous state of the structure, which permits us to eliminate the mechanism of transfer of the ions by electron jump. A comparative study of transport across a polymer inclusion membrane (PIM) and a supported liquid membrane (SLM) containing the same carrier in chloroform has shown that uranium or molybdenum transport efficiency was increased using PIM instead of SLM. PIM showed higher stability than SLM, the flux of transport remain constant in the former case after 2 weeks. 相似文献
127.
Yughandhar Sreedhar Neelam Rekha Dasari P. Reddy Prasad M. Sankar Nayak 《Journal of Saudi Chemical Society》2010,14(2):149-155
A novel analytical reagent 4-(2-hydroxy phenyl ethaminodiol), benzene-1,3-diol(4-2-HPEDB-1,3,D) was synthesized for the determination of molybdenum(VI). The present paper reveals the detailed study of electroanalytical behaviour for [Mo-(4-2-HPEDB-1,3,D)] complex under optimized conditions. The peak obtained for [Mo-(4-2-HPEDB-1,3,D)] prevent the interference of foreign ions which shows the sensitivity of the proposed method. The linearity was maintained at the concentration range of 0.5–200 μg/mL at pH 4.5 with correlation factor 0.9997. The present method was successfully applied for the analysis of molybdenum(VI) in biological fluids and plant material. The results obtained from the proposed method show good agreement with reference method. 相似文献
128.
129.
Imran Murtaza Ibrahim Qazi Khasan S. Karimov Muhammad H. Sayyad 《Physica B: Condensed Matter》2011,406(3):533-536
We use experimental results of direct current and low signal impedance spectroscopy to investigate the conduction mechanism in organic semiconductor ZnPc. The experimental results demonstrate an increase in current and holes mobility by the introduction of a thin MoO3 film at the ITO/ZnPc interface. This significantly improves the device performance. The improvement is explained in terms of the reduction in the effective barrier for charge transfer from ZnPc to ITO. 相似文献
130.
Samiha SalmaouiFaouzi Sediri Néji GharbiChristian Perruchot Salah AeiyachIwona A. Rutkowska Pawel J. KuleszaMohamed Jouini 《Applied Surface Science》2011,257(19):8223-8229
Tungsten trioxide, unhydrated with hexagonal structure (h-WO3), has been prepared by hydrothermal method at a temperature of 180 °C in acidified sodium tungstate solution. Thus prepared h-WO3 has been characterized by X-ray diffraction (XRD) method and using electrochemical techniques. The morphology has been examined by scanning and transmission electron microscopies (SEM and TEM) and it is consistent with existence of nanorods of 50-70 nm diameter and up to 5 μm length. Cyclic voltammetric characterization of thin films of h-WO3 nanorods has revealed reversible redox behaviour with charge-discharge cycling corresponding to the reversible lithium intercalation/deintercalation into the crystal lattice of the h-WO3 nanorods. In propylene carbonate containing LiClO4, two successive redox processes of hexagonal WO3 nanorods are observed at the scan rate of 50 mV/s. Such behaviour shall be attributed to the presence of at least two W atoms of different surroundings in the lattice structure of h-WO3 nanorods. On the other hand, in aqueous LiClO4 solution, only one redox process is observed at the scan rate of 10 mV/s. The above observations can be explained in terms of differences in the diffusion of ions inside two types of channel cavities existing in the structure of the h-WO3 nanorods. Moreover, the material can be applied as active support for the catalytic bi-metallic Pt-Ru nanoparticles during electrooxidation of ethanol in acid medium (0.5 mol dm−3 H2SO4). 相似文献