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31.
32.
Transcutaneous immunization (TCI) is a new needle-free vaccination technology with the potential to reduce the risk of needle-borne disease transmission and carcass damage within the livestock industries. The principal antigen-presenting cell involved in TCI is thought to be the epidermal Langerhans cell. Langerhans cell function is inhibited by cutaneous ultraviolet-B radiation (UVB) exposure. Such exposure may inhibit TCI through sun exposed skin sites due to the phenomenon of local low dose photoimmunosuppression. TCI of cattle to cholera toxin (CT) resulted in the generation of a serum anti-CT-specific IgG(2) response. However, exposure of cattle to a sub-inflammatory dose of simulated solar UVB (2.43 x 10(3)J/m(2)) significantly (P<0.05) inhibited TCI to CT via irradiated skin sites.  相似文献   
33.
Successful fisheries management systems tend to be underpinned by harvest strategies, specifying formally agreed data collection systems, assessment approaches and management measures used to regulate fishing pressure. While harvest strategies can be effective even in data- and capacity-limited (DCL) situations, their development remains challenging in such contexts. We present a process and decision-support tool, FishPath, to guide the identification of suitable harvest strategy component options given often debilitating conditions: (i) resource limitations and lack of technical management capacity; (ii) ‘uniqueness’ of DCL fisheries; (iii) the concept of harvest strategies is unfamiliar to managers and scientists, and the universe of options is hard to navigate; and (iv) the lack of an effective participatory process to identify solutions tailored to local contexts. These conditions can lead to either management paralysis or generic solutions that may be poor fits to specific conditions. The FishPath Tool uses a diagnostic questionnaire that elicits the key characteristics and specific circumstances of a fishery. It compares these with the requirements of alternative options from an inventory of possible harvest strategy components, identifies where these requirements are met and provides customised, transparent guidance on the appropriateness of component options of a harvest strategy, specific to the fishery of interest and its governance context. The FishPath Process is a facilitated multi-stakeholder, participatory engagement process aimed to set fisheries on the path to develop a harvest strategy. The FishPath Process and Tool combine to ensure a bottom-up, documented, transparent, replicable and efficient process.  相似文献   
34.
The retention of nutrients in farm ponds has many potential benefits, including reduction of nitrogen and phosphorus (promoters of eutrophication) in receiving streams. The aim of this study was to evaluate the efficacy of a commercial subsurface pond outflow control device (Pond Management System™) on nutrient retention in farm ponds. Four ponds of similar size and water chemistry in the upper Tar River basin of North Carolina, USA were studied; three were equipped with the pond outflow control device and one was retained without a device (normal surface outflow) that served as a reference site. Water samples were collected monthly from each pond at 0.3 m intervals from the surface to 2.1 m at a fixed station adjacent to the pond standpipe and from the pond outflow pipe from March to October 2005. The water samples were analyzed for total Kjeldahl nitrogen (N), total phosphorus (P), chlorophyll a, and a suite of other physicochemical variables. In ponds with the subsurface outflow device, the mean N concentrations in the outflow were substantially less (6.2–20.7%) than concentrations at the pond surface. Concentrations of N in the outflow were similar to N concentrations at intermediate pond depths (0.9–1.5 m), the depth of the outflow devices, indicating water was drawn from these depths and that N was being retained in the surface layers of the pond. Also, mean water temperatures were 1.1–1.9 °C cooler at intermediate depths compared to the surface, suggesting potential application of the outflow device for minimizing warm water outflows to receiving streams. These results provide evidence that under these conditions a subsurface pond outflow device can reduce nutrient release to receiving streams, thereby increasing overall stream water quality.  相似文献   
35.
The majority of the world's fisheries, by number, are data‐poor/limited, and there is a growing body of literature pertaining to approaches to estimate data‐limited stock status. There are at least two drivers for assessing the status of data‐limited fisheries. The first is to try to understand and report on the global or regional status of fisheries across many stocks. The second is to attempt to assess individual data‐limited stocks, for status reporting and/or guiding management decisions. These drivers have led to attempts to find simple, generic, low‐cost solutions, including the broad application of generically parameterised models, and the blanket application of a single, or limited number of possible, analytical approach(es). It is unclear that generic methods function as intended, especially when taken out of their original design context or used without care. If the intention is to resolve individual stock status for the purposes of management, there is concern with the indiscriminate application of a single method to a suite of stocks irrespective of the particular circumstances of each. We examine why caution needs to be exercised, and provide guidance on the appropriate application of data‐limited assessment methods (DLMs). We recommend: (a) obtaining better data, (b) using care in acknowledging and interpreting uncertainties in the results of DLMs, (c) embedding DLMs in harvest strategies that are robust to the higher levels of uncertainty in the output of DLMs by including precautionary management measures or buffers and (d) selecting and applying DLMs appropriate to specific species’ and fisheries’ data and context.  相似文献   
36.
The effects that fishes have on rates of one or more ecosystem processes (hereafter referred to as functional effects) are often invoked as an important reason for imperilled species conservation. However, the degree to which we understand these effects is rarely evaluated for most groups of fishes. We assessed how well the functional effects of freshwater and diadromous fishes, one of the most imperilled groups of animals, are quantified to date. We found that 88% of studies considering the functional effects of imperilled North American fishes were conducted on one family, Salmonidae. Studies of the functional effects of fishes were also concentrated in Pacific drainages of North America, with few studies in hotspots of imperilled fish diversity such as the Southeastern United States, the arid Southwest and central Mexico. Our results demonstrate the vast taxonomic and geographic gaps in our functional understanding of imperilled fishes and highlight the need to broaden this work to justify the argument that they are functionally important in the ecosystems they inhabit.  相似文献   
37.
Data availability, and unreported and unregulated fishing are significant obstacles to evaluating stock status, especially in tropical areas. Limitations in data quantity and quality can lead to model misspecification and erroneous data treatments, potentially causing important changes in model outputs and subsequent management implications. Red snapper Lutjanus purpureus (Poey) in French Guiana provides an example of a stock with a long-time series of fishery-dependent data subject to large uncertainty. A flexible catch-at-age model (Stock Synthesis) was applied to the available data and compared to an historically applied assessment approach. Inter-model variability based on different model specifications and data treatments were compared to identify better the status of the resource. Results showed that a major source of uncertainty in the model was the inclusion of a catch-per-unit-effort abundance index with questionable ability to track abundance. The Stock Synthesis model provided a more flexible and viable method than the virtual population analysis approach. Despite large uncertainty, models depicted a similar trend with a notable stock depletion in the late 1990s but with two distinct biomass trends in more recent years depending on the treatment. To reduce uncertainty and preserve this important economic resource, new data collection programmes and management policies are needed.  相似文献   
38.
The matric potential of soil water is probably the most useful assessment of soil water status. However, the water‐filled tensiometer (the benchmark instrument for measuring matric potential) typically only operates in the range 0 to ?85 kPa. In this paper, we report the development of a porous‐matrix sensor to measure matric potential in the approximate range ?50 to ?300 kPa. The sensor uses a dielectric probe to measure the water content of a ceramic material with known water retention characteristics. The calculation of matric potential takes into account hysteresis through the application of an appropriate model to measured wetting and drying loops. It is important that this model uses closed, rather than open, scanning loops. The calibrated sensors were tested in the field and the output compared with data from water‐filled tensiometers and dielectric measurements of soil water content. These comparisons indicated that conventional tensiometers gave stable but false readings of matric potential when soil dried to matric potentials more negative than ?80 kPa. The porous‐matrix sensors appeared to give reliable readings of matric potential in soil down to ?300 kPa and also responded appropriately to repeated wetting and drying. This porous‐matrix sensor has considerable potential to help understand plant responses to drying soil.  相似文献   
39.
Three reproductively quiescent female emus (Dromaius novaehollandiae) were embalmed with 10% formalin solution. The reproductive tract was dissected and described. The reproductive tract consists of an ovary and oviduct situated on the left side of the abdominal cavity. The left ovary is dark brown to black in colour with follicles covering the ventral surface. The ovary is located medial to the spleen and closely associated with the ventral surface of the cranial and middle lobes of the left kidney. The oviduct is a relatively straight tube that extends from the level of the cranial extent of the left ilium to the caudal border of the left pubic bone. The oviduct is grossly divided into the infundibulum, magnum, isthmus, uterus and vagina using variations in the mucosal fold pattern.  相似文献   
40.
The arterial supply of the ovary and oviduct is provided by the ovarian artery, cranial oviductal artery, accessory cranial oviductal artery, middle oviductal artery, caudal oviductal artery and the medial and lateral vaginal arteries. These arteries supply various regions of the oviduct and are branches of either the left cranial renal artery, left external iliac artery, left middle renal artery, left lateral caudal artery or the left pudendal artery. The veins that drain the reproductive tract are satellite vessels to each artery that supplied the tract.  相似文献   
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