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41.
Incoherent scattering functions S(x, Z) for six rare earth elements were evaluated from accurately measured whole atom differential incoherent scattering cross sections for 59.54 keV γ-rays scattered at 30°, 45°, 60° and 90° scattering angles corresponding to 1.24, 1.84, 2.40 and 3.39 Å−1 photon momentum transfers. Our results for S(x, Z) are the first for these rare earth elements. 相似文献
42.
The inclusion complexes of a series of 4-arylidenamino-5-phenyl-4H-1, 2, 4-triazole-3-thiols have been prepared with β-cyclodextrin. The compounds and their inclusion complexes have been characterized by studying their physical and spectral properties. The thermodynamic stability constant and free energy of activation have been determined to know the stability of inclusion complexes and type of host-guest relation. Finally, absorption, excitation and emission spectra of the compounds (4-arylidenamino-5-phenyl-4H-1, 2, 4-triazole-3-thiols) and their inclusion complexes have been taken. It is found that inclusion complex formation brings about a drastic change in absorption and fluorescence characteristic (both excitation and emission spectra) of newly synthesized compounds. 相似文献
43.
A. Gopalakrishna G. N. Kim H. Naik K. Kim B. K. Nayak Muhammad Zaman 《Journal of Radioanalytical and Nuclear Chemistry》2018,316(2):561-569
The production cross-section of the medical isotope, 99Mo from the enriched 100Mo(n,2n) reaction with the average neutron energies of 21.9 and 26.5 MeV has been determined for the first time by using an off-line γ-ray spectrometric technique. The average neutron energies were generated by using the 9Be(p,n) reaction with the proton energies of 35 and 45 MeV from the MC50 cyclotron of the Korea Institute of Radiological and Medical Sciences (KIRAMS) at Seoul, South Korea. The 100Mo(n,2n) reaction cross-section as a function of neutron energy was also calculated theoretically by using the computer code TALYS-1.8 and EMPIRE-3.2 Malta. The experimental results are in close agreement with the theoretical values from TALYS-1.8. However, the present data at the neutron energy of 21.9 MeV is slightly lower and at 26.5 MeV is higher than the values from EMPIRE-3.2 Malta. 相似文献
44.
Priyabrata Pattanaik Sabita Nayak Deepak Ranjan Mishra Pravati Panda Bishnu Prasad Raiguru Nilima Priyadarsini Mishra Seetaram Mohapatra N. Arjunreddy Mallampudi Chandra Shekhar Purohit 《Tetrahedron letters》2018,59(27):2688-2694
A competent and highly discriminating one-pot synthesis of highly diversified novel functionalized indenoquinoxalone grafted spiropyrrolidine linked chromene-3-carbonitrile conjugates accumulating three pharmocophoric cores, heterocyclic indenoquinoxalone, pyrrolidines and chromene-3-carbonitrile in a single molecular framework by means of 1,3-dipolar cycloaddition reaction between indenoquinoxalone, proline/benzyl amine and chromene-3-carbonitrile in ethanol under classical and microwave conditions is described. The three component 1,3-dipolar cycloaddition reaction proceeds via in situ generation of azomethine ylides by the decarboxylative condensation of indenoquinoxalone with proline/benzyl amine and their selectivity towards the endo cyclic double bonds of dipolarophile (chromene-3-carbonitrile) leading to the formation of highly functionalised regio- and diastereoselective molecular hybrids. This methodology exemplifies the green chemistry protocol such as mild reaction conditions, high yields, one-pot procedure and operational simplicity. 相似文献
45.
Vikas Jain A.K. Nayak P.K. Vijayan D. Saha R.K. Sinha 《Experimental Thermal and Fluid Science》2010,34(6):776-787
Natural circulation as a mode of heat removal is being considered as a prominent passive feature in the innovative nuclear reactor designs, particularly in boiling-water-reactors, due to its simplicity and economy. However, boiling natural circulation system poses many challenges to designer due to occurrence of various kinds of instabilities such as excursive instability, density wave oscillations, flow pattern transition instability, geysering and metastable states in parallel channels. This problem assumes greater significance particularly at low-pressures i.e. during startup, where there is great difference in the properties of two phases. In light of this, a parallel channel loop has been designed and installed that has a geometrical resemblance to the pressure-tube-type boiling-water-reactor, to investigate into the behavior of boiling natural circulation. The loop comprises of four identical parallel channels connected between two common plenums i.e. steam drum and header. The recirculation path is provided by a single downcomer connected between steam drum and header. Experiments have been conducted over a wide range of power and pressures (1–10 bar). Two distinct unstable zones are observed with respect to power i.e. corresponding to low power (Type-I) and high power (Type-II) with a stable zone at intermediate powers. The nature of oscillations in terms of their amplitude and frequency and their evolution for Type-I and Type-II instabilities are studied with respect to the effect of heater power and pressure. This paper discusses the evolution of unstable and stable behavior along with the nature of flow oscillation in the channels and the effect of pressure on it. 相似文献
46.
Rikarani R. Choudhury Smita Mohanty Sanjay Kumar Nayak 《International Journal of Polymer Analysis and Characterization》2019,24(4):334-345
This paper first time reports the preparation of random anionic copolymers from vinyl acetate (VAc) bearing electro-donating substituent and sodium 4-vinylbenzenesulfonate (SSA) having electro-withdrawing substituent. Copolymers (PVA-co-SSA) of different composition have been successfully prepared by a simple free radical solution polymerization technique. Resulting final copolymer contained neutral hydrophilic as well as ionizable ion exchange sites. Evaluation of spectral data obtained from Fourier transform Infrared spectroscopy, Raman spectroscopy, and 1H Nuclear magnetic resonance helped in identifying and confirming the chemical structure of copolymers. Characterization of copolymers by gel permeation chromatography revealed high molecular weight with moderate polydispersity index. Analysis of thermal stability and glass transition temperature of copolymers by thermogravimetric analysis and differential scanning calorimetry were found in between corresponding homopolymers. Physicochemical properties of PVA-co-SSA can be beneficial for prospective advanced application in the niche area of smart membrane technology for energy and environment. 相似文献
47.
Kamath Srinivas S. Narayana B. D’Souza Renita Shiny Nayak S. Rashmi Mohan M. P. Dileep B. N. Baburajan A. Ravi P. M. Karunakara N. 《Journal of Radioanalytical and Nuclear Chemistry》2019,322(2):389-397
Tritium concentration was monitored in different water sources collected around Kaiga Nuclear Power plant, India. The concentration was in the ranges?<?1.9–27.4 Bq L?1 (GM?=?4.0 Bq L?1) for groundwater,?<?1.9–42.1 Bq L?1 (GM?=?3.5 Bq L?1) for surface water and in 12.4–42.0 Bq L?1 (GM?=?24.07 Bq L?1) for reservoir water. The concentration values observed in this study are similar to those reported for other PHWR stations of the world. The radiation dose to the public due to ingestion of Tritium through groundwater was computed to be 0.08 μSvy?1.
相似文献48.
The reactivities of the stoichiometric and partially reduced rutile TiO2(110) surfaces towards oxygen adsorption and carbon monoxide oxidation have been studied by means of periodic density functional theory calculations within the Car-Parrinello approach. O2 adsorption as well as CO oxidation are found to take place only in the presence of surface oxygen vacancies (partially reduced surface). The oxidation of CO by molecularly adsorbed O2 at the O-vacancy site is found to have an activation energy of about 0.4 eV. When the adsorbed O2 is dissociated, the resulting adatoms can oxidize incoming gas-phase CO molecules with no barrier. In all studied cases, once CO is oxidized to form CO2, the resulting surface is defect-free and no catalytic cycle can be established. 相似文献
49.
Amal Halder Sandip K. Nayak Subrata Chattopadhyay Sumanta Bhattacharya 《Journal of solution chemistry》2012,41(2):223-240
The present article reports the host-guest complexation of a calix[4]arene derivative, namely 4-iso-propyl-calix[4]arene (1), with fullerenes (both C60 and C70) in toluene and benzonitrile solutions. It is observed that the charge-transfer (CT) absorption bands are located in the
ground state for the C60 and C70 complexes of 1. By utilizing the CT absorption bands, various important physicochemical parameters like the oscillator strength, resonance
energy, transition dipole moment, electronic coupling element and solvent reorganization energies have been estimated for
the C60-1 and C70-1 complexes. The CT transition energy is very helpful for determining the vertical ionization potential of 1 in solution. Jobs method of continuous variation was used to establish 1:1 stoichiometry for the fullerene complexes of 1. The most fascinating feature of the present study is that 1 binds C70 preferentially compared to C60 as obtained from binding constant (K) data. The effect of solvent on the complexation of fullerenes (C60 and C70) with 1 is clearly observed from the trend in the K values: in toluene and whereas in benzonitrile, and . Molecular mechanics force field (MMMF) calculations reveal fascinating features regarding the binding pattern of fullerenes
towards 1 in vacuo in terms of enthalpy of formation. MMMF calculations establish that during C70-1 complexation, C70 is directed in an end-on manner rather than the traditional side-on pattern. 相似文献
50.
Tandrima Chaudhuri Prashant Sukla Moumita Mahapatra Bipin Rooj Sandip K. Nayak Subrata Chattopadhyay Manas Banerjee 《Journal of solution chemistry》2012,41(1):143-155
Absorption and emission spectroscopic studies of (dibenzoylmethanato)boron difluoride (1bf) in various polar and non-polar, protic and aprotic solvents are reported. The solvatochromic shifts of the spectral bands
were examined in terms of solvent properties, including donor and acceptor numbers, followed by multilinear regression in
which several solvent parameters were simultaneously analyzed. This π-conjugated positively charged system exhibits excellent solvatochromism. Variations in the electronic absorption spectral
characteristics of 1bf were studied in solution in the presence of zinc perchlorate. Absorption spectral studies indicate stable complex formation
between the zinc ion and 1bf in the ground state in aprotic dipolar benzonitrile rather than in protic polar solvent methanol. Zinc ion binding of 1bf was theoretically rationalized through frontier molecular orbital interaction. 相似文献