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61.
Abrams GS Adolphsen CE Averill D Ballam J Barish BC Barklow T Barnett BA Bartelt J Bethke S Blockus D Bonvicini G Boyarski A Brabson B Breakstone A Bulos F Burchat PR Burke DL Cence RJ Chapman J Chmeissani M Cords D Coupal DP Dauncey P DeStaebler HC Dorfan DE Dorfan JM Drewer DC Elia R Feldman GJ Fernandes D Field RC Ford WT Fordham C Frey R Fujino D Gan KK Gero E Gidal G Glanzman T Goldhaber G Gomez Cadenas JJ Gratta G Grindhammer G Grosse-Wiesmann P Hanson G Harr R Harral B Harris FA 《Physical review letters》1989,63(26):2780-2783
62.
J. J. LaBrecque 《Journal of Radioanalytical and Nuclear Chemistry》1979,53(1-2):213-224
A rapid procedure for determining palladium in catalysts and geoiogical materials is presented. This method involves the use
of an241Am (100 mC) source for excitation and employs a PDP-11/05 processor for the data acquisition and analysis by energy-dispersive
X-ray fluorescence. The relative standard deviation for 5 independent determinations is less than 3% for 100 seconds of fluorescent
time. The calculated and measured values agreed well for both, the prepared standards and the doped Venezuelan laterites.
Finally, data on the different sources of error is given including counting time, sample preparation, and total error.
This investigation was funded in parts by CONICIT (Consejo Nacional de Investigaciones Científicas y Technológicas). 相似文献
63.
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66.
Jacobsen RG Koetke DS Adolphsen CE Fujino D Schumm BA Wagner SR Alexander JP Averill D Barish BC Barklow T Barnett BA Blockus D Boyarski A Brabson B Breakstone A Bulos F Burchat PR Burke DL Cence RJ Chapman J Chmeissani M Cords D Coupal DP Dauncey P DeStaebler HC Dorfan JM Drell PS Drewer DC Durrett D Elia R Feldman GJ Field RC Ford WT Fordham C Frey R Gan KK Gero E Gidal G Glanzman T Goldhaber G Gomez Cadenas JJ Gratta G Hanson G Harr R Harral B Harris FA Hayes K Hearty C Heusch CA 《Physical review letters》1991,67(24):3347-3350
67.
68.
Abrams GS Adolphsen CE Averill D Ballam J Barish BC Barklow T Barnett BA Bartelt J Bethke S Blockus D Bonvicini G Boyarski A Brabson B Breakstone A Bulos F Burchat PR Burke DL Cence RJ Chapman J Chmeissani M Cords D Coupal DP Dauncey P DeStaebler HC Dorfan DE Dorfan JM Drewer DC Elia R Feldman GJ Fernandes D Field RC Ford WT Fordham C Frey R Fujino D Gan KK Gero E Gidal G Glanzman T Goldhaber G Gomez Cadenas JJ Gratta G Grindhammer G Grosse-Wiesmann P Hanson G Harr R Harral B Harris FA 《Physical review letters》1990,64(12):1334-1337
69.
The concentration of137Cs, potassium, thorium and uranium for 6 monitoring sites and 32 other sites at the Venezuelan Institute for Scientific Research (IVIC) were presented, as well as, the estimated air dose and exposure rates for each site. The concentration of137Cs was found to be much higher at many sites at IVIC in respect to the average estimated value of137Cs in Venezuela. But, this was determined to be due to a natural cause, the cloud forest which surrounds the higher elevations. The values of potassium, thorium and uranium were compared to values from other parts of northern Venezuela and were found to agree for sites at similar elevations. They were also shown to be about two to three times higher than global estimates. Thus, the air dose and exposure rates were correspondingly two to three times higher too, but the annual dose from the primordial radionuclides in the soil was estimated to be less than 0.1 mSv, which is considered negligible for health risks. 相似文献
70.
J. J. LaBrecque P. A. Rosales P. R. Cordoves 《Journal of Radioanalytical and Nuclear Chemistry》2002,253(1):87-92
Soils were collected at different elevations (m.a.s.l.) near the two roadways, that pass through the Henri Pittier National Park (Edo. Aragua, Venezuela) in order to determine the distribution of the concentrations of the 137Cs fallout and its relation to the tropical cloud forest. Duplicate samples were taken at most elevations between 2–5 cm below the soil surface to confirm that the samples were representative of the area. In many cases, it was difficult or impossible to locate areas that were undisturbed by man or nature. The 137Cs (Bq/kg) content was determined by conventional high resolution gamma ray spectroscopy employing a standard comparison method. The background of the 137Cs fallout in soils, below the cloud (fog) baseline was calculated to be about 5 Bq/kg on both the south (land) side and north (ocean) side for both roadways. The concentrations of 137Cs (Bq/kg) were between 2–3 times higher at the baseline of the cloud (fog) on both sides of the mountain range. The 137Cs values at the highest elevations (1105 and 1625 m.a.s.l.) near the roadways were about 5–6 times higher than the determined background levels. Our estimates of the baseline of the cloud (fog) are in good agreement with other visual observations. Finally, we have concluded that the distribution of 137Cs in soils in cloud forests can be employed to estimate the baseline and the concentrations of 137Cs fallout can be related to the relative density of the cloud (fog) when it was deposited. 相似文献