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481.
Sleep facilitates memory consolidation. A widely held model assumes that this is because newly encoded memories undergo covert reactivation during sleep. We cued new memories in humans during sleep by presenting an odor that had been presented as context during prior learning, and so showed that reactivation indeed causes memory consolidation during sleep. Re-exposure to the odor during slow-wave sleep (SWS) improved the retention of hippocampus-dependent declarative memories but not of hippocampus-independent procedural memories. Odor re-exposure was ineffective during rapid eye movement sleep or wakefulness or when the odor had been omitted during prior learning. Concurring with these findings, functional magnetic resonance imaging revealed significant hippocampal activation in response to odor re-exposure during SWS. 相似文献
482.
Bjørn O. Eggum Inge Hansen Torben Larsen 《Plant foods for human nutrition (Dordrecht, Netherlands)》1989,39(1):13-21
Chemical analyses and balance trials with rats of 17 foods showed marked differences in protein quality. According to anin vitro procedure true protein digestibility was high (around 90%). The same was also the case for thein vivo values with the exception of two legumes, beans and chick peas, which were digested to a markedly lower degree when compared to thein vitro values. The assumed reason for this is discussed. Due to extensive differences in the amino acid composition of the 17 samples BV varied considerably with the lowest value (45.5) of rice-wheat gluten breakfast cereal. Energy digestibility was generally high. Amino acid digestibility determinedin vivo followed the pattern of the corresponding protein digestibility, although marked differences occurred from one amino acid to another in the same food. 相似文献
483.
J.B. Holland Å. Bjørnstad K.J. Frey M. Gullord D.M. Wesenberg T. Buraas 《Euphytica》2000,113(3):195-205
In order to test if selection can improve a population's adaptation to diverse environments simultaneously, three cycles of
recurrent selection based on grain yield in Iowa, Idaho, and Norway were practiced in an oat (Avena sativaL.) population developed from North American, Scandinavian, and wild species (A. sterilis L.) germplasm sources. Specific objectives were to determine if selection: increased mean yields across environments and
within all environments; changed the genetic correlation of yields in different environments; and changed genetic variation
for yield within the population. We evaluated 100 to 210 randomly-chosen families from each cycle of selection at three Iowa
locations, in Idaho, and in Norway for two years. Grain yield within each location and mean yields across locations increased
significantly over cycles of selection. Mean yields across locations expressed as a percent of the original population mean
increased at a rate of 2.6% per year. Several families from the third cycle population exhibited both high mean yields across
locations and consistently high yields within all locations. Average genetic correlations of yield in different environments
were higher in the second cycle than in the original population. A trend of reduced genetic variation and heritability was
observed in Iowa only. These results suggest that we successfully improved mean population yield both within and across locations,
and yield stability across environments, and in developing families with outstanding adaptation to diverse environments.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
484.
Bulk milk samples from 2236 dairy herds randomly selected throughout Sweden in proportion to region and herd size were analysed for antibodies to bovine coronavirus (BCV) in an ELISA. The results were expressed as optical density (OD) values and an OD > 0.04 was considered positive. Eighty-nine per cent of the samples were antibody-positive and 52 per cent had high levels of antibodies to BCV (an OD > 0.70). There were significantly higher OD values (P < 0.001) and fewer antibody-negative samples (P < 0.001) from larger herds than from smaller herds. There were also significantly higher OD values and fewer antibody-negative samples from herds in southern Sweden than from herds in northern Sweden (P < 0.001 and P < 0.001, respectively). These results indicate a higher frequency of BCV infections in larger herds and in herds in southern Sweden. 相似文献
485.
The objective of this study was to record how the antibody levels change over time during pregnancy in dairy cows naturally infected with the protozoan parasite Neospora caninum, and relate this to the reproductive performance. Eighteen cows with antibodies to N. caninum were serum sampled monthly during their first pregnancy and 13 of them were also followed for a second pregnancy. In all, five pregnancies ended in abortion and two in stillbirth. Antibodies to N. caninum in serum were demonstrated by immune stimulating complex enzyme-linked immunosorbent assay (iscom ELISA). The N. caninum antibody titres remained well above the 1:100 cut-off limit for the test used during 2 years in all cows. In the non-aborting cows, mean values of antibody titres to N. caninum rose 1.5-2.5 dilution steps to reach a plateau 4-5 months before parturition, and thereafter decreased from 2 months before parturition. These changes were statistically significant (p < 0.001). The same pattern was seen in the aborting cows. The consistent pattern of rise in antibody titres observed during both pregnancies in all cows indicated a reactivation rather than a reinfection of the parasite at mid-gestation. 相似文献
486.
Areas a few square metres in size, devoid of higher vegetation other than moss, have been mapped at 600–700 m above sea level in the mountains of the western part of central Norway. The moss is covered by a grey precipitate during dry summer periods. The precipitate has been identified by ICP-AES analysis of HNO3-extract, X-ray diffraction (XRD) and by scanning electron microscopy (SEM) as an aluminium(Al)-hydroxide, probably amorphous Al-hydroxide and diaspore (Al(OH)3), containing 21–25% Al by weight. In comparison, the underlying moraine deposits contain 1.5–3.5% Al by weight. A small spring, where groundwater discharges, is located uphill of each contaminated area. The Al content of the water which emerges from these springs decreases downhill away from the spring and is inversely proportional to the pH. The runoff waters originating at the springs have been modelled using the computer-codes MINTEQA2 and ALCHEMI and are found to be saturated with respect to amorphous Al(OH)3. This study raises the very important question as to what extent a lower pH in the influent meltwater may leach out more aluminium and possibly lead to the formation of larger amounts of precipitate. 相似文献