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71.
Increased planting of hard mast oak species in the Lower Missouri River floodplain is critical as natural regeneration of oak along the Upper Mississippi and Lower Missouri Rivers has been limited following major flood events in 1993 and 1995. Traditional planting methods have limited success due to frequent flood events, competition from faster growing vegetation and white-tailed deer herbivory. Results of early growth response of swamp white oak (Quercus bicolor Willd.) seedlings in relation to initial acorn mass and size, and early rapid shoot growth for seedlings produced by containerized root production method (RPM™), are presented. Containerized RPM™ seedlings grown in the greenhouse under optimal conditions demonstrate that seed size had no discernable impact on first-year root or shoot size. Seedling survival for the first two years and acorn production for the first three years after outplanting are presented, comparing use of containerized RPM™ swamp white oak seedlings to nursery stock. Flood tolerant precocious RPM™ oak seedlings in the floodplain provide a source of food for acorn-consuming wildlife ten to fifteen years sooner than oaks originating from natural regeneration, direct seeding or traditional bare root planting. Compared to bare root nursery stock that produced no acorns, some RPM™ swamp white oak seedlings averaged 4.3, 5.2, and 6.3 acorns/seedling in the first three years after fall outplanting. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   
72.
Dey  Daniel C.  Parker  William C. 《New Forests》1997,14(2):145-156
The value of initial stem diameter near the root collar, shoot length and number of first-order lateral roots (FOLR) as morphological indicators of stock quality and field performance was examined for bareroot (1+0, undercut) red oak (Quercus rubra L.) underplanted in a shelterwood in central Ontario. These three attributes were measured on more than 400 seedlings prior to planting, and their relationship with height and basal diameter growth two years after planting was determined using correlation and regression analysis. Initial diameter, shoot length and number of FOLR were positively and significantly correlated with second-year height and diameter. These relationships were strongest for diameter, but this variable explained less than 25% of the total variation in growth. Of the three indicators, diameter was also the best predictor of several physical characteristics of root systems two years after planting. Initial diameter was significantly correlated with root volume, root area and lateral root, taproot and total root dry mass. Weaker relationships existed between initial shoot length and number of FOLR and second-year root system features. Stem diameter two years after planting was more strongly related to root volume, area and dry mass than was initial diameter, the probable result of adjustment in root-shoot balance of planting stock to the shelterwood environment.  相似文献   
73.
A recombinant LipL 32 antigen-based dipstick ELISA was developed as a screening test for the detection of leptospiral antibodies in serum samples from dogs. The antibodies were detected by a change in the colour of the substrate solution when the recombinant antigen-coated dipsticks were dipped into it. The relative sensitivity, specificity and accuracy of the test, compared with the standard microscopic agglutination test, were 95.9 per cent, 93.8 per cent and 94.8 per cent, respectively.  相似文献   
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In determining the effect of prior feeding of antimicrobials on subsequent antimicrobial therapy in induced colibacillosis of piglets with Escherichia coli serotype O62 (Dey et al., 1977), study groups in one trial developed spontaneous colibacillosis due to a different Escherichia coli serotype O147. This paper reports the results and conclusion drawn from this outbreak.

Both groups, irrespective of antimicrobial feeding, developed disease, and the attack rates for the groups were not significantly different. Neither mortality nor the clinical course of illness in animals without therapy changed significantly as a function of antimicrobial feeding. The antimicrobial feeding had no effect on the therapeutic efficacies of chloramphenicol or chlortetracycline utilized for treating the disease. Chloramphenicol therapy was more effective in terminating the disease.  相似文献   

77.
Tropical Animal Health and Production - The low potency of genetic immunization has to date impeded development of commercial vaccines against major infectious diseases. The aim of this study was...  相似文献   
78.
DNA barcoding represents an objective tool for fast species identification, especially for taxa for which morphological identification is difficult. One current limitation of barcoding is the lack of reference sequences for many groups. While many European and North American countries have started their own barcoding initiatives to generate complete local inventories and databases, such efforts are sparse for African, Asian and South American countries, despite their high biodiversity and comparably poorly explored faunas. Therefore, it is important to start local barcoding efforts in such countries. In this study we performed DNA barcoding for the band-winged grasshoppers of the Biskra province in Algeria, a region of high diversity for this taxon. All specimens were identified morphologically and then barcoded. We generated a total of 47 sequences of the COI gene for 22 morphologically identified species of Oedipodinae, many of which were sequenced for the first time. We present the data in a phylogenetic tree, which suggests monophyly for most genera, but rejects it for Sphingonotus and Vosseleriana. Statistical species delimitation worked well for most genera, except those within the Sphingonotini, likely because these have radiated rather recently. Together with data sourced from the literature we used our new data set to generate an updated list of band-winged grasshoppers for the region. Several species are recorded for the region and for the country for the first time. One species appears to be new to science. Furthermore, we found geographic variation within several more widespread species for which data from other countries were present. We consider the new data as an important resource for future faunistic, ecological and biodiversity studies and point out the importance of local (taxon-specific) barcoding studies.  相似文献   
79.
Gynoecism has been used on a large scale in heterosis breeding of cucumber. Production of hybrid seeds in bitter gourd is highly expensive because it is done mainly through hand pollination. But utilization of a gynoecious line would be more economical and easier method. Since gynoecious parent has only female flowers, the open pollinated seeds it produces will be F1 hybrid. It will reduce the cost of male flower pinching and hand pollination. Two gynoecious lines, DBGY-201 and DBGY-202 were crossed with two monoecious cultivars, “Pusa Do Mausami” and “Pusa Vishesh” and their F2 populations were observed to determine the inheritance pattern of gynoecious sex form. Another experiment was conducted to determine magnitude of heterosis by utilizing nine inbred lines including one gynoecious line, DBGY-201 in diallel (without reciprocal) mating system. All the gynoecious hybrids showed significant heterosis in a desirable direction for traits like sex ratio (male:female), days to first picking, number of fruits per plant, yield per plant, and vine length. The segregation pattern in F2 suggested that gynoecious sex form in bitter gourd was governed by single recessive gene. The gynoecious hybrids DBGY-201 × “Pusa Vishesh” and DBGY-201 × “Pusa Do Mausami” were important for early harvest (~50 days after sowing) whereas DBGY-201 × “Priya” and DBGY-201 × “Arka Harit” were promising for higher yield.  相似文献   
80.
Light is the most common limiting factor in forest plant communities,influencing species composition,stand structure,and stand productivity in closed canopy stands.Stand vertical light structure is relatively simple under a closed canopy because most light is captured by overstory trees.However,wind disturbance events create canopy openings from local to landscape scales that increase understory light intensity and vertical light structural complexity.We studied the effects of an EF-1 tornado on horizontal and vertical(i.e.three-dimensional)light structure within a Quercus stand to determine how light structure changed with increasing disturbance severity.We used a two-tiered method to collect photosynthetic photon flux density at 4.67 m and 1.37 m above the forest floor to construct three-dimensional light structure across a canopy disturbance severity gradient to see if light intensity varied with increasing tornado damage.Results indicate that increased canopy disturbance closer to the tornado track increased light penetration and light structure heterogeneity at lower forest strata.Increased light intensity correlated with increased sapling density that was more randomly distributed across the plot and had shifted light capture higher in the stand structure.Light penetration through the overstory was most strongly correlated with decreased stem density in the two most important tree species(based on relative dominance and relative density)in the stand,Quercus alba L.(r=-0.31)and Ostrya virginiana(Mill.)K.Koch(r=-0.27,p<.01),and indicated that understory light penetration was most affected by these two species.As managers are increasingly interested in patterning silvicultural entries on natural disturbances,they must understand residual stand and light structures that occur after natural disturbance events.By providing spatial light data that quantifies light structure post-disturbance,managers can use these results to improve planning required for long-term management.The study also provides comparisons with anthropogenic disturbances to the midstory that may offer useful comparisons to natural analogs for future silvicultural consideration.  相似文献   
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