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991.
农业植物有害生物疫情调查是保护农业生产安全的基础工作,建立有害生物疫情数据库可以科学指导植物检疫。开展检疫性有害生物的检疫防控,能有效地防止其进一步传播蔓延。  相似文献   
992.
OBJECTIVE: To compare the attitudes of French veterinarians to pain, and their provision of analgesia to animals, with that reported from other countries. STUDY DESIGN: Epidemiological study. METHODS: In June 1999, 379 French veterinarians were surveyed to ascertain their views on pain evaluation and control in dogs and cats, and their use of analgesics in daily practice. Survey results are expressed as a percentage of responses. RESULTS: The questionnaire was returned by 189 veterinarians (49.9%). The response rate was influenced by age (younger veterinarians were more likely to respond) but not gender. A majority (99.5%) expressed moderate to extreme concern over pain in their patients. Pain evaluation was based on the animal's attitude (88.3% dogs, 82.5% cats), interaction with the caregiver, response to palpation of the painful area (66.5% dogs, 62.7% cats) and inappetence (29.3% dogs, 46.3% cats, p < 0.001). Only 14.3% of respondents considered their knowledge of pain recognition to be inadequate. Many (58.8%) considered their methods of pain quantification and control (47% dogs, 59% cats) to be inadequate. Difficulties in recognizing pain (58.3%), a lack of knowledge in the appropriate use of analgesics (41.7%) and fear of drug side effects (30%) were used to explain inadequate provision of analgesia. Only 16.1 and 8.1% used opioids in dogs and cats, respectively. This low level of use resulted from the imposition of French narcotic legislation (79.9%) and lack of knowledge of opioid pharmacology (73.7%). Nonsteroidal anti-inflammatory drugs (NSAIDs) and glucocorticoids were the most commonly used analgesics in both species (100% (dogs) and 96.7% (cats)). The most popular NSAID used in France was tolfenamic acid, followed by meloxicam (dogs), ketoprofen, nimesulide (cats) and carprofen (dogs). The type of surgery performed influenced the use of analgesics, from 17.2% for castration to 83.7% for orthopaedic procedures. Nonsurgical conditions believed to warrant analgesia included osteoarthritis (97.8%), trauma (97.3%) and bone neoplasia (93.4%). Female veterinarians were more likely than males to evaluate pain and provide analgesia. CONCLUSION: French practitioners demonstrate a level of interest in analgesia, which appears to be at least equivalent to that reported from English-speaking countries. The signs used to indicate the presence of pain do not, in general, appear to differ. Excessive confidence in their ability to recognize pain (despite a general ignorance of the subject), the minor role of animal health technicians in pain management and misconceptions about analgesics (mainly opioids) are French pecularities.  相似文献   
993.
我国东北烟区典型烟田土壤系统分类研究   总被引:1,自引:1,他引:0  
以黑龙江的宁安、吉林的汪清和辽宁的宽甸为我国东北烟区的代表,通过15个典型优质烟田的土壤调查,本研究尝试建立相应的土系。结果表明:①调查的15个典型烟田土壤在系统分类上可归为3个土纲(淋溶土、雏形土和新成土)、5个亚纲、6个土类、7个亚类、11个土族和土系。②不同土系的烟田各有优劣,属于不同土纲的土系在植烟适宜性上有很大差异,淋溶土的土系有效土层深厚,养分含量适中、比例协调,劣势在于黏化层存在可能会限制根系下扎;属于雏形土和新成土的土系优势在土壤颗粒较粗,通透性好,养分含量虽然低但易于通过施肥调控,劣势在于有效土层偏薄。  相似文献   
994.
Changes in soil organic carbon (SOC) storage in agricultural land are an important part of the Land Use, Land-Use Change and Forestry component of national greenhouse gas emission inventories. Furthermore, as climate mitigation strategies and incentives for carbon farming are being developed, accurate estimates of SOC stocks are essential to verify any management-induced changes in SOC. Based on agricultural mineral soils in the Danish soil-monitoring network, we analysed management effects on SOC stocks using data from the two most recent surveys (2009 and 2019). Between 2009 and 2019, the average increase in SOC stock was 1.2 Mg C ha−1 for 0–50 cm despite a loss of 1.2 Mg C ha−1 from the topsoil (0–25 cm), stressing the importance of including deeper soil layers in soil-monitoring networks. Comparing all four national surveys (1986, 1997, 2009, 2019), the mean SOC stock of mineral soils in Denmark appears stable. The change in SOC stock between 2009 and 2019 was analysed in detail in relation to management practices as reported by farmers. We found that the effects of single management factors were difficult to isolate from co-varying factors including soil parameters and that the use of farm management data to explain changes in SOC stocks observed in soil-monitoring networks appears limited. Uncertainty in SOC stock estimates also arises from low sampling frequency and statistical challenges related to regression to the mean. However, repeated stock measurements at decadal intervals still represent a benchmark for the overall development in regional and national SOC storage, as affected by actual farm management.  相似文献   
995.
  1. Monitoring the abundance of mobile and wide‐ranging cetacean populations for conservation management is challenging, especially when the management is focused on static protected areas. Where abundance estimates are derived from mark–recapture data, such as photo‐identification of naturally marked individuals, unpredictable movements of animals in and out of the survey area can reduce ‘capture’ probabilities and affect the precision and accuracy of resulting estimates.
  2. A Bayesian hierarchical log–linear model was applied to photo‐identification data collected in summer 2014 to derive a multi‐site abundance estimate for a population of bottlenose dolphins, Tursiops truncatus, ranging widely throughout the coastal waters of western Ireland. In addition, the effects of varying levels of sampling effort on the minimum detectable decrease in population size were examined.
  3. The abundance (median) of dolphins was estimated as 189 (coefficient of variation (standard deviation/mean), 0.11; 95% highest‐posterior density interval, 162–232). Over 50% of the well‐marked dolphins encountered throughout the study were sighted in more than one distinct coastal area, thus displaying high mobility. In addition, it was found that it would require biennial surveys to detect a 25% decline in abundance within the six‐year reporting period of the EU’s Habitats Directive.
  4. Given that the Special Area of Conservation designated for these dolphins consists of two separate areas covering a substantial portion of the west coast of Ireland, the multisite approach is appropriate for monitoring this population. It produces a more precise estimate and is well suited for sparse recapture data collected opportunistically at multiple sites, when the lack of resources prevents large‐scale surveys or when concentrating surveys on smaller localized areas fails to capture the broad range and unpredictable occurrence of the animals. The Bayesian multi‐site approach could be applied to the management of other wide‐ranging marine or terrestrial taxa.
  相似文献   
996.
  1. Marine communities have long been impacted by human activities, but the quantification of human‐driven changes often relies on recent data. This is because historical data on fish populations are lacking and are challenging to include in contemporary stock and ecological assessments. As a result, the impacts of early fishing pressure on marine communities are generally poorly documented worldwide.
  2. Marine communities of Southeast Australia have a relatively short history of exploitation compared with other temperate systems and were sampled before and after the onset of commercial fishing. As such, they provide a rare opportunity to identify historical baselines and to understand ecological changes after the onset of commercial exploitation.
  3. This study compares survey data collected around Tasmania, Southeast Australia, in 1909–1910 with data from the 1980s. The period considered precedes the establishment of a trawl fishery in Southeast Australia in 1915, of other important commercial fisheries in Tasmania, and of a fisheries data collection programme in 1984. Nominal catch rates are used to examine changes across all families of demersal fish recorded in catches and generalized linear models are used to estimate and compare standardized indices of abundance between the 1909–1910 and 1980s data for key commercial families.
  4. Results show significant, and thus far unreported, fishing‐induced changes in marine communities after the establishment of commercial fishing in the region. Changes mostly relate to shifts in catch composition and steep declines in the abundance of the main commercial families.
  5. This study illustrates a method for analysing low‐quality historical catch data and provides estimates of pre‐commercial fishing abundance that can be included in stock and ecological assessments. More broadly, this study demonstrates the significant role of early fishing in shaping marine communities and increases our understanding about general patterns of exploitation that have been difficult to identify with longer but less detailed fishing histories.
  相似文献   
997.
We carried out a trawl-depletion experiment for benthic fauna in an area closed to commercial trawling. A 12-fathom prawn (shrimp) trawl net having a swept path of about 18 m was towed 13 times along each of six tracks. Each track was 2.7 km long and known from previous surveys to contain several relatively dense patches of megabenthos. The depletion rate was assumed to vary between trawls on a given track, and was modelled by a beta distribution defined by a mean rate and a dispersion parameter. Maximum likelihood analysis of the sequence of catches on each track suggests that a single trawl removes a small, but non-negligible, fraction of the benthos. The combined effect of 13 trawls on each track, assuming the trawls were aligned, was to remove a substantial proportion of the initial biomass. Gastropods suffered the greatest impact (an estimated 95% removed, on average). Ascidians, sponges, echinoids, crustaceans and gorgonians were depleted by an estimated 74–86%, and all other taxonomic groups except algae (27% removed) were reduced by at least 54%. Using differential global positioning systems and careful navigation, we aimed to achieve a high degree of overlap between successive trawls. Nonetheless, records show that the trawler deviated from this path and it is likely that the net did not sweep exactly the same path during the 13 trawls on each track. A simulation study was conducted to examine the effect on parameter estimates of ignoring the probable non-alignment of trawls. There was little bias in the estimate of the dispersion parameter. With the level of dispersion found on these tracks, the estimated mean depletion rates would, however, have been biased (upwards when the true mean depletion rate was below 15%, downwards when the true mean depletion rate was above 15%). This means that most mean depletion rates estimated from the catch data are probably biased by 2–3%. The depletion rates estimated from this study may be acceptable in areas that are trawled infrequently or sparsely. However, the cumulative effect of frequent trawls in an area of high intensity trawling is likely to be substantial both in terms of organisms directly affected by trawling and indirectly due to attracting scavengers and removing refuge habitat for fish and other mobile organisms.  相似文献   
998.
  1. Conservation efforts have increased in response to global mussel declines, and effective surveys are a crucial step in assessing and monitoring mussel populations and in determining their conservation status. The burrowing behaviour of mussels can affect their detectability, and a better understanding of these behaviours would help to improve survey design and guidelines.
  2. The burrowing depth of mussels may differ between seasons, habitat conditions, species, and individuals, and little is known about the burrowing behaviour of mussels in subtropical rivers.
  3. Burrowing depth variation was examined and compared at three sites in the San Marcos, Guadalupe, and San Antonio river drainages in central Texas. In addition, laboratory experiments were used to determine whether observed differences between field sites and seasons could be linked to differences in substrate type and water temperature and to examine differences between species.
  4. Seasonal variation in burrowing depth was found at all field sites, and water temperature was a significant factor for explaining variation in burrowing depth, but there was no clear relationship between burrowing depth and temperature in shorter term laboratory experiments, where individual variation was high and burrowing behaviour seemed to be solely a function of time.
  5. Mussels burrowed significantly deeper in finer substrate (sand vs. gravel) in both field and laboratory experiments. Few significant differences between species were found in the field, but no differences were found in the laboratory experiments.
  6. The results suggest that surveys may need to follow different guidelines depending on local conditions, such as substrate and water temperature. Surveys will be less efficient and may fail to detect larger proportions of populations in colder water temperatures. In addition, a larger proportion of burrowed mussels can be expected at sites with finer substrate, such as sand. Under these conditions, visual searches will not suffice, as a large part of the population or specific species may be overlooked.
  相似文献   
999.
The planning and initial phases of a joint Nordic project for the valuation of recreational fisheries is described. The economic value of recreational fisheries was taken to include non-market value as well as the traditional market value. The design of the survey was similar for each country so as to facilitate future comparison. However, initially there were difficulties in defining categories of recreational fishermen in the different countries. Other background information also had to be adapted to national circumstances. National population registers were used as the sampling frames. The effect of this on the responses from a valuation survey is discussed. Accessibility to population register data varies by country and so do possibilities for random sampling. Legal constraints were faced when implementing a centralised mailing system.  相似文献   
1000.
Marine aquaria claim that they help to elevate the current low profile of marine conservation through public education. The effectiveness of aquaria as centres for marine conservation education was assessed using social survey techniques, at three large commercial aquaria in the south-west of England. The aquaria managers did not believe that most visitors were interested in receiving educational information, in particular on conservation topics. Textual analysis revealed that aquaria's interpretative material contained very few references to conservation and portrayed a distorted image of the marine environment. The feedback from the questionnaires revealed no evidence for an increase in visitors' sympathy towards and understanding of marine conservation following a visit to an aquarium. The majority of visitors wanted public aquaria to increase their levels of interpretation. In particular, visitors wanted more information on conservation and how they, as individuals , could contribute to preserving the marine environment. As well as benefiting conservation, increasing the educational impact of aquaria could have significant commercial advantages, e.g. increased visitor satisfaction and numbers. Suggestions on how these mutual benefits could be achieved are briefly outlined. Their success will depend on the degree of cooperation which can be forged between commercial aquaria and conservationistsThis revised version was published online in October 2005 with corrections to the Cover Date.  相似文献   
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