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21.
22.
Jale Müslehiddino?lu Yusuf Uluda? Hilmi Önder Özbelge Levent Yilmaz 《Journal of membrane science》1998,140(2):396-266
Performance of continuous polymer enhanced ultrafiltration (PEUF) method was investigated for removal of mercury and cadmium from binary mixtures. This method includes the addition of polyethyleneimine (PEI) as a water soluble polymer to bind the metals, which was followed by ultrafiltration operation performed on both laboratory and pilot scale systems. The influence of various operating parameters such as temperature, metal/polymer ratio, presence of calcium ions and pH on retention of metals and permeate flux was investigated. To investigate the possibility of selective separation of mercury and cadmium, experiments were conducted for binary solutions at different pH and loading ratios. It was seen that the retention of mercury decreased and permeate flux increased when the temperature increased. The increased pH and decreased metal/polymer ratio, loading (L), resulted in higher retention of both metals. Shapes of retention vs. pH or L curves were very similar for both metals. Retentions stay almost constant at a value very close to unity until a critical L or pH value was reached, then, R decreases almost linearly with L or pH. However, retention of cadmium was affected more than that of mercury as the pH decreased and L increased. This leads to the selective separation of mercury and cadmium. At low pH values (about 5) and at high L values (about 0.3), mercury was removed by ultrafiltration operation while almost all cadmium passed through the membrane. At pH 5.5 and cadmium/polymer ratio about 0.35 and mercury/polymer ratio about 0.39, the highest separation factor was obtained as 49. 相似文献
23.
G. Buchbauer H. Spreitzer B. Öckher C. Pretterklieber I. Piringer P. Wolschann 《Monatshefte für Chemie / Chemical Monthly》1995,126(4):467-472
Summary Guided by molecular modeling studies, the synthesis of the title compound is described. The organoleptic evaluation proved the predicted real sandal like odour of (Z)-dehydro-homo--santalol.
Aus den Diplomarbeiten von C.P. (1991), I.P. und B.Ö. (1992), Universität Wien 相似文献
24.
Jochum KP Stoll B Pfänder JA Seufert M Flanz M Maissenbacher P Hofmann AW Hofmann AW 《Fresenius' Journal of Analytical Chemistry》2001,370(5):647-653
Spark source mass spectrometry (SSMS) has experienced important and significant improvements in nearly all analytical features by the use of a multiple ion counting (MIC) system. Two procedures have recently been developed to further increase the analytical capabilities of MIC-SSMS in geochemistry. These are a mathematical correction of interferences, which is often necessary for the ultra trace element analysis of Nb, Ta, Zr, Hf and Y, and the development of an autospark system to hold the total ion beam constant. New analytical data for geological samples, especially international reference materials, are presented using the improved MIC-SSMS technique. The data set consists of high precision and low abundance data for Zr, Nb and Y in depleted reference materials. The MIC-SSMS results are compared with those of conventional SSMS using photoplates for ion detection. The precision of the MIC-SSMS isotope ratio measurements (about 1%) is more than a factor of 3 better than that of conventional SSMS, as demonstrated by analyses of Hawaiian samples. Total uncertainties of MIC-SSMS concentration data including all sources of error are generally between 2 and 5% for concentrations higher than about 0.3 microg/g and about 10% for trace element abundances in the ng/g range. 相似文献
25.
A. Hollnder J. E. Klemberg-Sapieha M. R. Wertheimer 《Journal of polymer science. Part A, Polymer chemistry》1995,33(12):2013-2025
The emission from low-pressure microwave plasmas in the vacuum-ultraviolet (VUV) region (λ < 200 nm) was investigated in order to use these plasmas as light sources for the study of the VUV photochemistry of polyethylene (PE) and polypropylene (PP) as part of the study of plasma-polymer interaction. These polymers, immersed in low-presure oxygen, were exposed to radiation with wavelengths down to 112 nm, the cut off of magnesium fluoride used as a window to separate the polymer specimen from the plasma light source. Total oxygen incorporation in the surface [O], and the formation of hydroxyl, carbonyl, and carboxyl groups were measured using XPS in combination with chemical derivatizations, particularly their dependence upon the radiation spectrum and the oxygen pressure around the sample. In most experiments the surface oxygen concentration [O] attained a constant value that appears to be related to the initial oxidation rate; this suggests a competition between oxygen incorporation and chain scission reactions, followed by the removal of volatile oxidation products. PE is usually oxidized to a higher level than PP, the latter appearing to be more susceptible to reaction with atomic oxygen than PE. A general initiation mechanism for the VUV experiments is proposed that allows us to explain the observed differences in behavior between PE and PP, and the results obtained under different irradiation conditions. The nature of oxidation products is in both cases very similar to what is observed after direct plasma treatment of the polymers. We conclude that short wavelength radiation contributes very appreciably to the observed surface modification effects during plasma treatment of PE and PP. © 1995 John Wiley & Sons, Inc. 相似文献
26.
Two new vic-dioxime ligands and their complexes with Co+2, Ni+2, Cu+2, Cd+2, and Zn+2 ions were synthesized. Primer amines (3,4-methylenedioxaaniline and 4-methylbenzylamine) reacted with antichloroglyoxime
to give 3,4-methylenedioxaphenylaminoglyoxime (H2L1) and N-(4-methylbenzyl)aminoglyoxime (H2L2) ligands. Structures of the ligands and their complexes are proposed based on elemental analyses, IR, UV-Vis, and 1H NMR spectra, magnetic susceptibility measurements, and thermogravimetric analyses (TGA).
The article was submitted by the authors in English. 相似文献
27.
This study aims to clarify the effects of carbon activation type and physical form on the extent of adsorption capacity and
desorption capacity of a bi-solute mixture of phenol and 2-chlorophenol (2-CP). For this purpose, two different PACs; thermally
activated Norit SA4 and chemically activated Norit CA1, and their granular countertypes with similar physical characteristics,
thermally activated Norit PKDA and chemically activated Norit CAgran, were used. The thermally activated carbons were better
adsorbers for phenol and 2-CP compared with chemically activated carbons, but adsorption was more reversible in the latter
case. 2-CP was adsorbed preferentially by each type of activated carbon, but adsorption of phenol was strongly suppressed
in the presence of 2-CP. The simplified ideal adsorbed solution (SIAS) model underestimated the 2-CP loadings and overestimated
the phenol loadings. However, the improved and modified forms of the SIAS model could better predict the competitive adsorption.
The type of carbon activation was decisive in the application of these models. For each activated carbon type, phenol was
desorbed more readily in the bi-solute case, but desorption of 2-CP was less compared with single-solute. This was attributed
to higher energies of 2-CP adsorption. 相似文献
28.
A. Küçükönder B. G. Durdu Ö. Sö?üt E. Büyükkasap 《Journal of Radioanalytical and Nuclear Chemistry》2004,260(1):89-97
L X-ray fluorescence cross sections, and intensity ratios were measured for elements in the 70£Z£92 atomic range at the excitation energy 59.5 keV using a Si(Li) detector. Furthermore, L X-ray fluorescence cross sections
and intensity ratios were calculated for elements in the same range. The average L shell fluorescence yields were derived
using experimental L X-ray fluorescence cross sections and theoretical photoionization cross sections. The obtained results
were compared with other experimental and theoretical values.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
29.
H. A. Ergül S. Topcuo?lu E. Ölmez Ç. K?rbaşo?lu 《Journal of Radioanalytical and Nuclear Chemistry》2006,268(1):133-136
Summary Radionuclide (137Cs, 238U, 232Th and 40K) concentrations were determined in a sediment trap and bottom sediment samples collected from a station at the eastern Turkish
coast of the Black Sea. The specific activity of the 137Cs radionuclide in the settling particles ranged from 0.04±0.01 to 0.10±0.02 Bq. g-1dry weight. The calculated flux rate of the 137Cs was between 0.37 and 2.59 Bq. m-2. d-1in the sampling periods of 2002 and 2003. The 137Cs concentration in the bottom sediment profile were between 0.039±0.013-9.083±0.017 Bq. g-1dry weight in the same station. The vertical profile of the radionuclides suggests that they have little mobility during the
17 years after the Chernobyl accident. 相似文献
30.
8-Hydroxyquinoline (8-HOQ) is known as an important chelating agent for several metal ions. This compound is practically insoluble in water. For this reason, in this study its water soluble sulfate salt has been used for complexing uranyl ions and the stability constants of the complex have been determined. The Irving-Rosotti method computing the Calvin-Bjerrum pH-titration data, was applied. Finally, the stability constants of the complex formed between (8-HOQN-H)2SO4 and uranyl ions were found to be lgK1=8.25 and lgK2=4.15, the overall stability constant being {ie55-1}. 相似文献