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41.
A 2 x 2 factorial arrangement of treatments with 78 mature ewes was used to evaluate the effects of supplementing the pregnant ewe's diet with high levels of minerals and vitamin E on immunoglobulin G (IgG) absorption by the lamb and whether any altered efficacy of IgG absorption was due to the colostrum or to the lamb. The ewes were estrus-synchronized in October and housed in wk 10 of gestation. In the final 7 wk of gestation, a grass silage-based diet, offered ad libitum, was supplemented with 500 g of a 19% CP concentrate, and from 1 wk later until lambing, half the ewes was offered 48 g of a mineral/vitamin supplement containing 6.5 g of Ca, 4.9 g of P, 5.9 g of Mg, 4.0 g of Na, 790 mg of Zn, 3.5 mg of Se, 40 mg of I, 200 mg of Mn, 20 mg of Co, and 40 IU of vitamin E. At birth, the lambs were allocated to one of four treatments in a 2 x 2 factorial arrangement, with lamb origin and colostrum origin as the two factors. The lambs born to ewes not offered the mineral supplement were fed colostrum obtained from their own dams or from ewes in the mineral-supplemented treatment, whereas lambs born to ewes given supplemental minerals were fed colostrum obtained either from their dams or from ewes in the control treatment. The ewes were milked at 1, 10, and 18 h postpartum and the lambs were fed using a stomach tube. A 5-mL blood sample was taken from each lamb at 24 h postpartum for IgG analysis. The level of fecal adhesion to the upper tail/rump area of the lamb was subjectively scored at 72 h postpartum. There was no difference in gestation length, lamb birth weight, colostrum yield, or IgG production (P = 0.16 to 0.82). When ewes were fed supplemental minerals, the serum IgG content of the progeny was lower than in their control counterparts (6.8 vs. 16.1 g/L; P < 0.001), regardless of whether the lamb received colostrum from ewes with or without access to supplementary minerals. The difference in serum IgG concentrations at 24 h postpartum was a direct reflection of a compromised efficiency in IgG absorption. The progeny of ewes with access to minerals had higher (P < 0.05) levels of fecal adhesion, which was not related to the origin of the colostrum, indicating altered digestive function in these lambs. We conclude, using the sheep as a model, that high mineral intakes in late pregnancy not only lower serum IgG concentrations in the lamb, but also that high mineral intakes result in the neonate being preprogrammed at birth so that it is born with a compromised ability to absorb colostral IgG. 相似文献
42.
F. Deng G. J. Boland 《European journal of plant pathology / European Foundation for Plant Pathology》2006,114(2):127-137
The hypovirulence-associated mitovirus, Ophiostoma mitovirus 3a (OMV3a), has been shown to be widespread in eastern Canadian populations of Sclerotinia homoeocarpa in the form of latent infection. Latent infection by OMV3a was not associated with an apparent phenotype and did not significantly
reduce the growth and virulence of the pathogen. In the present study, we found that isolates of S. homoeocarpa latently infected by OMV3a can change to hypovirulent isolates after storage at 4 °C, and that this attenuation of virulence
was associated with increased concentration of the OMV3a virus. Recurrent observations revealed that up to 29.8% of latently
infected isolates changed to hypovirulent isolates after 21 months of storage. Transmission of OMV3a dsRNA from latently infected
isolates to virus-free isolates resulted in latent infection of the recipient isolates, indicating that latent infection by
OMV3a was not associated with genetic differences in the fungal host. The RNA genomes of the OMV3a virus in an isogenic pair
of latently infected and hypovirulent isolates were sequenced and compared. Each of the two RNAs contained an open reading
frame of 726 amino acids with conserved motifs typical of RNA-dependent RNA polymerase (RdRp). The OMV3a RNA sequences in
these two isolates share 95.1% nucleotide and 94.6% amino acid sequence identities. The development of hypovirulence from
latent infection by OMV3a virus may provide new strategies to improve the biological control efficacy of hypovirulence in
dollar spot management. 相似文献
43.
ABSTRACT Interspecific transmission of a hypovirulence-associated double-stranded RNA (dsRNA) and hypovirulent phenotype was attempted from hypovirulent isolate Ss275 of Sclerotinia sclerotiorum to five virulent isolates of S. minor. dsRNA and the hypovirulent phenotype were successfully transmitted to one of the five isolates, Sm10. Three putative converted isolates of Sm10 were slow growing and developed atypical colony morphologies characteristic of the hypovirulent phenotype. These isolates were assayed for virulence and produced significantly smaller lesions than isolate Sm10 on detached leaves of Romaine lettuce. One of these putative converted isolates, designated Sm10T, was tested to confirm interspecific transmission of dsRNA. In northern hybridizations, dsRNA isolated from Sm10T hybridized with a digoxigenin-labeled cDNA probe prepared from dsRNA isolated from Ss275. Random amplified polymorphic DNA analysis confirmed that isolate Sm10T was derived from Sm10 and not from Ss275 or a hybrid of the two species. The dsRNA and hypovirulent phenotype were subsequently transmitted intraspecifically from Sm10T to Sm8. To our knowledge, this is the first report of interspecific transmission of dsRNA and an associated hypovirulent phenotype between fungal plant pathogens by hyphal anastomosis. 相似文献
44.
Tommy Firman 《Asia Pacific viewpoint》1999,40(1):45-58
This paper examines patterns of migration in Jakarta City based on the 1995 Intercensal Survey (SUPAS) Data. It shows the emergence of female in-migration in response to the shift of economic activities in the city from manufacturing industries to services and finance sectors. The study also documents migration from Jakarta, the core of Jabotabek (Jakarta Metropolitan Area) to the fringe areas, which reflects the physical as well as socio-economical restructuring of this Metropolitan Area. 相似文献
45.
Soil solutions expelled by high‐speed centrifugation (13900 g) of intact soil sample cores at field moisture from 30 forest topsoils (A horizons of mainly Dystric and Eutric Cambisols, according to the FAO‐Unesco system) low in clay were subjected to analysis of 60 elements, using ICP‐MS and ICP‐AES. Concentrations measured were related to soil and soil solution properties assumed to be important for the solubility of elements, using stepwise regression analysis. On an average two thirds of the variability in soil solution concentration of elements were accounted for by, in particular, organic C concentrations, pH and/or nitrate concentrations of the solutions, varying among elements from 19 to 90 %. Concentrations of elements strongly positively related to soil solution acidity were Al, Be, Ge, Li, Ni, Pb, and Zn, strongly negatively related to acidity were Ca, Mo, and W. Most positively related to nitrate concentrations in soil solutions were B, Ba, Cd, Mg, Mn, and Sr; negatively were Nb, Ta, and Ti. Concentrations of organic C in the soil solutions correlated positively, often quite closely, with most of the other elements studied, including La, all the lanthanides, and with Ag, Br, Cr, Fe, Ga, Hf, Hg, In, P, Th, U, Y, and Zr. Soluble organic compounds were apparently ’︁carriers’ of these elements in the soil solution. The concentrations of elements in HNO3 digests of the soils usually accounted for just little or no statistical variability of their soil solution concentrations. 相似文献
46.
47.
A chemically induced dimer configuration was prepared on the silicon (Si) (100) surface and was characterized by scanning tunneling microscopy (STM) and spectroscopy (STS). These prepared dimers, which are essentially untilted and differ both electronically and structurally from the dynamically tilting dimers normally found on this surface, are more reactive than normal dimers. For molecular hydrogen (H2) adsorption, the enhancement is about 10(9) at room temperature. There is no appreciable barrier for the H2 reaction at prepared sites, indicating the prepared configuration closely approximates the actual dimer structure in the transition state. This previously unknown ability to prepare specific surface configurations has important implications for understanding and controlling reaction dynamics on semiconductor surfaces. 相似文献
48.
Giuliano EA Maggs DJ Moore CP Boland LA Champagne ES Galle LE 《Veterinary ophthalmology》2000,3(2-3):153-156
The objective of this study was to describe method of placement, and frequency and severity of complications associated with a subpalpebral lavage system placed in the medial aspect of the equine inferior eyelid. The inferomedial subpalpebral lavage (ISPL) tube is positioned deep in the medial aspect of the inferior conjunctival fornix so that the footplate lies flat between the lower eyelid and the anterior surface of the nictitans. Retrospective data from the placement of 92 ISPL systems placed in 86 horses during a 31-month period were examined. Tube placement was performed using sedation and regional anesthesia only in 59% of horses. The median duration of tube placement was 19 days (range: 1-61 days). Seventy-one horses were treated for up to 55 days following discharge from hospital with an ISPL tube in place. No complications were reported with 59% of ISPL systems. Non-ocular complications were found in 38% of ISPL systems and included tube displacement from the conjunctival fornix (18%), suture loss requiring resuturing of the system to the horse's head (14%), and damage necessitating replacement of the injection port (6%). Ocular complications were recorded in 3% of horses and were limited to inferior eyelid swelling. Vision was retained in 88% of horses. The ISPL system is easily and safely placed, and well tolerated for extended periods. It appears to be associated with infrequent and minor complications when compared with placement of subpalpebral lavage tubes in the superior eyelid. 相似文献
49.
50.
The management of water resources by orchards in the south-eastern region of Australia is an increasingly important policy
issue, especially given the low water allocations and concerns about salinity in recent years. Optimal management for economic
and environmental sustainability can be described as best management practice (BMP). A project was developed to run an extension
program, which aimed to achieve behavioural change among orchardists through the adoption of irrigation BMPs and benchmarks.
The effectiveness of the extension program was evaluated and the drivers for adoption assessed. In the first stage of the
project both BMPs and benchmarks were determined for irrigation management. A survey of 200 growers showed no relationship
between yield and irrigation system or irrigation volume suggesting that increased yields were not a key driver for adoption
of sustainable irrigation practices. Stage two of the project involved undertaking an extension program aimed to facilitate
the adoption of BMPs and benchmarks and incorporated a suite of activities to meet the learning needs of a diversity of participants
(40 growers). The program was effective in establishing behavioural change for many of the growers involved; however, it was
resource intensive requiring significant one-on-one input. Stage three aimed to analyse the key drivers for adoption of sustainable
irrigation practices for the whole of the stone and pome fruit industry in south-eastern Australia using market research.
The study determined that water use efficiency was not a key driver for adoption of sustainable irrigation practices (micro
irrigation and soil moisture monitoring) and adoption was generally not limited by lack of knowledge. Groups of growers were
identified where extension programs could be effective by focussing on specific information e.g. redevelopment of orchard.
Other groups had no need and/or ability to change unless the external operating environment was to change e.g. regulation,
access to pressurised water. The voluntary adoption of more sustainable irrigation practices will probably require extensive
resources using one-on-one methodology. The extension program should not focus on the broader social objective of improved
water use efficiency but promote other potential benefits (e.g. labour saving, redevelopment of production systems, management
flexibility) with targeted messages for specific groups. 相似文献