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341.
We used leaf-litter and bark-litter bags to examine the colonization patterns of microarthropods in arboreal and soil microhabitats
of a Cryptomeria japonica plantation. The mass loss of leaf-litter was slower in the arboreal environment than in the soil environment. The variation
in leaf-litter mass among litter bags increased markedly with increasing decomposition in the soil, and was smaller in the
arboreal environment. The colonization processes of microarthropods differed between the arboreal and soil leaf-litter bags.
In the arboreal bags, Collembola, Gamasida, and Prostigmata had a peak density in the summer of the second year after establishing
the bags whereas Oribatida maintained relatively constant densities until 15 months. In the soil bags, Collembola colonized
the litter first, and Gamasida and Prostigmata subsequently colonized the more decomposed litter. The vertical colonization
patterns of the major microarthropods were consistent at all heights on the tree trunk. Slow decomposition in arboreal litter
reflected severe conditions for most decomposers throughout the experimental study. In contrast, severe conditions of arboreal
litter may lead to a relatively stable resource for limited microarthropods that have physiological tolerance for unfavorable
conditions. Because of the traits of these fauna, the arboreal litter may thus be utilized seasonally by Collembola and Gamasida,
but continuously by Oribatida. We suggest that soil microarthropods would be more affected by successional changes than by
seasonal changes, because of faster decomposition of the litter, whereas arboreal microarthropods would be more affected by
seasonal changes because of slow decomposition processes in the arboreal environment. 相似文献
342.
We investigated an upstream area of the 1926 Taisho Mudflow that occurred at Mount Tokachi, a volcano in central Hokkaido, Japan, to clarify the relationship between natural forest succession and mudflow-induced sediment characteristics. The study area was divided into three parts, i.e., undisturbed, deposition, and scoured areas, based on disturbance regimes. The deposition area was further divided into three different forest stands for a final total of five forest stand types. We assumed that the mudflow regimes created sediment edaphic heterogeneity and undisturbed and island forests supplied seeds for natural revegetation. The undisturbed forest stand comprised pioneer species, whereas a mosaic forest consisting of almost pure stands characterized by Betula ermanii and Picea glehnii developed in the mudflow. This indicates that each plant species has a characteristic ability to establish and adapt initially and later develop into a mosaic forest according to sediment edaphic conditions, particularly depth, grain size distribution, and water and nutrient gradients. The differences in forest species composition and a 30-year time lag between the development of forest stands at the distal edges and the center explain how the cross-sectional sediment edaphic heterogeneity created by the mudflow regimes affected succession and forest development. Furthermore, plants are specific to sediment depth and texture, as well as moisture and nutrient availability, which play important roles in their growth and development; thus, forest stands with contrasting species and age structures developed in the mudflow. 相似文献
343.
A Homo erectus calvarium [Sambungmacan 4 (Sm 4)] was recovered from Pleistocene sediments at Sambungmacan in central Java. Micro-computed tomography analysis shows a modern human-like cranial base flexion associated with a low platycephalic vault, implying that the evolution of human cranial globularity was independent of cranial base flexion. The overall morphology of Sm 4 is intermediate between that of earlier and later Javanese Homo erectus; apparent morphological specializations are more strongly expressed in the latter. This supports the hypothesis that later Pleistocene Javanese populations were substantially isolated and made minimal contributions to the ancestry of modern humans. 相似文献
344.
Vitamin B12 is synthesized by only certain bacteria and archaea but not by animals or plants. In marine environments, bacterial vitamin B12 is transferred and concentrated into fish and shellfish bodies by plankton in the marine food chain. Moreover, marine macrophytic red algae, Porphyra spp. specifically contain substantial amounts of vitamin B12, due to microbial interaction. Although some meats or viscera of edible fish and shellfish are excellent sources of biologically active vitamin B12, an inactive corrinoid, pseudovitamin B12, was found in some edible shellfish using liquid chromatography/electrospray ionization–tandem mass spectrometry. To prevent elderly people from developing vitamin B12 deficiency due to food protein-bound vitamin B12 malabsorption, we present a survey of marine foods containing free vitamin B12. The results of our study suggest that bonito and clam extracts (or soup stocks), which contain considerable amounts of free vitamin B12 are useful not only as seasonings and flavorings but also as excellent sources of free vitamin B12. 相似文献
345.
Excretion rates of indigestible plastic balls of different specific gravities and diameters in dairy cattle 下载免费PDF全文
We used plastic balls to investigate how their specific gravity and diameter affect excretion rate and rumination in dairy cattle, to develop a capsule that can be used for reaching the lower gastrointestinal tract without physical breakdown and/or degradation in the rumen. Twelve types of indigestible plastic balls composed of a combination of four specific gravities (0.95, 1.19, 1.41, or 2.20) and three diameters (3.97, 6.35, or 7.94 mm) were orally administered to lactating dairy cows, and the balls were collected from feces, after 120 h post‐administration, to evaluate the recovery rate. Recovery rate of the balls with specific gravity 1.19 or 1.41 and diameter 6.35 or 7.94 mm was higher than those with specific gravity 0.95 or 2.20 and diameter 3.97 mm. The cumulative recovery rate at 24 and 48 h post‐administration was higher for balls with specific gravity 1.19 than that for balls with other specific gravities. These results suggest that specific gravity 1.19 or 1.41 and diameters 6.35?7.94 mm are optimal for use in bypass capsules for administration to cattle. In addition, the passage time of capsules differed between specific gravities 1.19 and 1.41. 相似文献
346.
Tomohiro Nishigaki Kazuki Kobayashi Yohey Hashimoto Method Kilasara Haruo Tanaka 《Soil Science and Plant Nutrition》2018,64(3):291-299
ABSTRACTSoil phosphorus (P) forms have been practically defined as chemically fractionated pools. A knowledge of the abundance and diversity of P forms in soil, and the factors affecting them, will lead to better soil management. However, little is known about the differences in P forms among soils with different geological properties in tropical Africa. The aim of this study was to investigate the P forms in soils with different physicochemical properties formed under different geological conditions in southern Tanzania and to identify the factors affecting the P forms in these soils. In total, 37 surface soil samples were collected from three geological groups; the plutonic (mainly granite) rock (PL) group, the sedimentary and metamorphic rock (SM) group, and the volcanic ash (V) group. Soil P was sequentially extracted by NH4Cl, NH4F, NaHCO3, NaOH + NaCl, and HCl, and inorganic (Pi) and organic P (Po) in each fraction were determined. The lowest total P was in the PL group (average, 360 mg P kg-1) because of the high sand content. Iron (Fe)-P (NaOH-Pi) was the major form in this group, accounting for 8.4% of total P. In the SM group (average total P, 860 mg P kg-1), Fe-P was the major form in most, accounting for 7.8% of total P. Soils in the SM group occasionally had high calcium (Ca)-P due to application of chemical fertilizer at the collection site. The V group had the highest total P (average, 1600 mg P kg-1) and its major P form was Ca-P, which was possibly derived from primary minerals (i.e., apatite), accounting for 14% of total P. In addition, the high oxalate-extractable Al possibly caused the accumulation of Al-P in the V group. Oxalate-extractable Fe generally increased with increasing Fe-Pi, while oxalate-extractable Al increased with increasing organic P and Al-Pi in soils in all three geological groups. These results demonstrate that the soil P forms differ greatly among sites in southern Tanzania with different geological conditions and associated soil properties. 相似文献
347.
We have modeled the prey–predator dynamics between nutrients, phytoplankton, and copepods in Hiuchi-nada, central part of
the Seto Inland Sea. The model parameters were estimated by stepwise regression using data sampled from 2001 to 2005. We re-created
the fluctuations in copepod biomass in the spring–summer of 2001–2004 by model simulation and investigated the relationship
between the re-created copepod biomass and anchovy Engraulis japonicus reproductive success rate in Hiuchi-nada. The anchovy reproductive success rate was proportional to the copepod biomass during
the last 10 days of May, a period that immediately preceded anchovy recruitment. This relationship indicates that a possible
key factor in the regulation of anchovy population levels is the fluctuation in abundance of the copepod assemblage and that
the crucial period for anchovy recruitment in Hiuchi-nada would be the period just before anchovy recruitment to the shirasu
(body length: approx. 20–35 mm) fishery. These results provide a potential framework for forecasting the anchovy recruitment
level that is based on both larval abundance and survival rate as estimated from the biomass of copepods in the pre-recruitment
period of anchovy. 相似文献
348.
Yui KOBAYASHI Tatsuro NAKAMURA Tomohiro YONEZAWA Koji KOBAYASHI Takahisa MURATA 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》2021,83(12):1977
Bacterial cystitis is one of the feline lower urinary tract diseases (FLUTDs). Polyunsaturated fatty acids, such as arachidonic acid (ARA), docosahexaenoic acid (DHA), and eicosapentaenoic acid (EPA), are oxidized into various lipid mediators that modulate inflammation. Since the profile of lipid metabolites excreted in urine is useful for assessing inflammatory body conditions, we analyzed 126 types of urinary lipid metabolites in cats with bacterial cystitis. Using LC-MS/MS, we found that the levels of 11 metabolites were higher in the urine of cystitis cats than in the urine of healthy cats. In detail, the urinary levels of ARA, EPA, and DHA and eight of their metabolites were increased in cystitis cats. Focusing on the lipid oxidation pathway, the urinary levels of four cyclooxygenase-, three lipoxygenase-, and one cytochrome P450-dependent oxidated metabolites were increased in bacterial cystitis. These urinary lipid profiles can provide some insight into the pathology and future diagnosis of bacterial cystitis. 相似文献
349.