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Quantitative Changes Associated with Calving in the Levels of Bovine Immunoglobulins in Selected Body Fluids I. Changes in the Levels of IgA, IgG1 and Total Protein
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J. E. Butler C. S. Pierce C. A. Rock C. A. Kiddy 《Canadian journal of veterinary research》1972,36(3):234-242
Levels of bovine IgA, IgG1 and total protein (TP) were determined in serum, saliva, tears and individual quarter lacteal secretions of six Holstein-Friesian cows sampled from six weeks before to four weeks after parturition. Hierarchal analyses of variance indicated significant variations among weeks, cows and quarters of the udder. A precipitous but non proportional drop in the levels of IgA and IgA1 in lacteal secretions occurred at calving. There was a concomitant increase in IgG1, and decrease in IgA, in serum. Correlation studies supported the concept of selective transport of IgG1 from serum to lacteal secretions in regulated amounts independent of serum IgG1 levels. Changes in the IgG1/TP ratio of serum and lacteal secretions supported the idea of a decrease in the selective transport mechanism. Correlation studies and estimations of secretory IgA (SIgA) in serum suggest that serum IgA is derived from IgA synthesized in secretory tissues. Highly significant correlations between IgA and IgG1 levels in all secretions postpartum suggest that local IgA synthesis and either IgG1 transport or local IgG1 synthesis are initiated by the same stimuli. Although some of the variation in the level reported for IgA and IgG1 in secretions resulted from protein dilution, much of the variation represents physiological differences between individual animals and tissues in the same animal. An IgG2/IgG1 ratio approaching that of serum occurred in a mastitic quarter of one cow. IgA was the principal immunoglobulin in saliva and tears, comprised a greater proportion of the immunoglobulin in milk whey than in prepartum lacteal secretions and was a minor immunoglobulin in bovine serum. 相似文献
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J. W. Hornbeck C. T. Smith Q. W. Martin L. M. Tritton R. S. Pierce 《Forest Ecology and Management》1990,30(1-4):55-64
Effects of whole-tree clearcutting are being studied in three major forest types in the northeastern United States: a spruce-fir forest in central Maine, a northern hardwood forest in New Hampshire, and a central hardwood forest in Connecticut. At each site we sampled total and extractable nutrient capitals, inputs and outputs of nutrient ions in precipitation and streamflow, nutrient removals in harvested products, and nutrient accumulation in regrowth. Depending upon location, combined losses of nutrients in harvested products and increased leaching to streams were in the ranges of 374–558 kg ha−1 for Ca, 135–253 kg ha−1 for K, 50–65 kg ha−1 for Mg, 248–379 kg ha−1 for N, and 19–54 kg ha−1 for P. Opportunities for replacing these losses over the next rotation are best for N. Data on inputs in precipitation versus outputs in streamflow indicate that, once effects of harvest subside, most N in precipitation will stay within the forest. By contrast, Ca shows a net output of 8–15 kg ha−1 year−1 from uncut watersheds, and the added leaching losses due to harvest may have a serious impact on Ca capital. This is especially the case for the Connecticut site, where total site capital for Ca is only about 4000 kg ha−1. 相似文献
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Summary A considerable amount of data has been collected over the past few years on the rupture life of particleboard. This information is particularly valuable at the present time because there is increasing interest in the use of particleboard as a structural material. This paper presents a conventional analysis of the time to failure of three commercially available brands of particleboard at 20°C and at three fixed levels of relative humidity. A linear relationship is assumed between the logarithm of time to failure and stress level, and an improvement is made in the usual method of analysis by including censored specimens. The regression lines are projected forward to give estimates of the stress levels that can be sustained for a particular design life. It is found that the regression lines for 30 per cent and 65 per cent rh may be combined, but the specimens at 90 per cent rh are significantly lower in strength at any given time. One of the MUF bonded boards performs significantly better than a second MUF board over the long term, and this gives added weight to the view that there are other factors in the make-up and production of the board that are at least as important as the resin type itself. 相似文献
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Evolving agricultural policies have influenced management practices within agroecosystems, impacting available habitats for
many species of wildlife. Enhancing wildlife habitat has become an explicit objective of existing agricultural policy. Thus,
there is renewed focus on field borders and the use of shelterbelt agroforestry systems to achieve conservation goals in the
Midwest. Two Representative Farms – a 283-ha dryland and 510-ha irrigated farm were created in Saunders County, Nebraska.
The Habitat Analysis and Modeling System (HAMS) was used to describe the composition and spatial pattern of the existing farms
and surrounding landscape, as well as for the landscapes surrounding selected Breeding Bird Survey (BBS) routes. Simulated
land use changes resulting from the implementation of two shelterbelt scenarios, Agricultural and Wildlife, were incorporated
on each Representative Farm and surrounding landscape. Landscape variables which influence breeding bird species richness
and community composition as determined from BBS routes were measured on simulated farm landscapes. A more heterogeneous landscape
results from implementing either scenario. The percent total woods was a significant determinant of bird species richness
on the BBS routes and was important in influencing bird communities at the farm- and landscape-level. Other landscape metrics
which influenced the bird community composition on BBS routes were woody edge percentages and edge density values. Policies
promoting shelterbelts create edge habitats which ultimately favor birds within the Forest-edge/generalist guild while bird
species in need of conservation such as grassland-field species would potentially be negatively affected.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献