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91.
The relentless need for the discovery and development of new agrochemicals continues as a result of driving forces such as loss of existing products through the development of resistance, the necessity for products with more favorable environmental and toxicological profiles, shifting pest spectra, and the changing agricultural needs and practices of the farming community. These new challenges underscore the demand for novel, high‐quality starting points to accelerate the discovery of new agrochemicals that address market challenges. This article discusses the efforts to identify the optimum ranges of physicochemical properties of agrochemicals through analysis of modern commercial products. Specifically, we reviewed literature studies examining physicochemical property effects and analyzed the properties typical of successful fungicides, herbicides, and insecticides (chewing and sap‐feeding pests). From the analysis, a new set of physicochemical property guidelines for each discipline, as well as building block class, are proposed. These new guidelines should significantly aid in the discovery of next‐generation agrochemicals. © 2018 Society of Chemical Industry  相似文献   
92.
In soils, amino acids may be an important source of nitrogen for plants, at least in those where organic matter is not quickly degraded. The physiology of uptake of amino acids by roots was mainly studied in the 70's and 80's, before genes encoding amino acid importers were cloned in the 90's. While two families of amino acid transporters have been identified, yielding a total of about 100 genes, the role of each member is yet to be elucidated. As a tool for studying the role of amino acid transporters from Arabidopsis we set up a new hydroponic system suitable for radioisotope use. This system enables reproducible amino acid uptake by roots and estimation of the transport to the shoots of the amino acid taken up. We show that the rates of glutamine (Gln) uptake by wild‐type roots and transfer to the shoots were linear, and that other tested amino acids were translocated to the shoots with lower efficiency than Gln. A T‐DNA insertion mutant for a Gln exporter was compared to the wild‐type plants. Gln uptake and transfer were similar in both genotypes, showing that the suppression of the exporter did not affect uptake or transfer of amino acids to the shoots. The main advantage of the hydroponic system presented here is that all the materials used to grow Arabidopsis are virtually free and can therefore be discarded, a useful feature when working with radioactivity.  相似文献   
93.
Meta‐analysis has been an integral tool for fisheries researchers since the late 1990s. However, there remain few guidelines for the design, implementation or interpretation of meta‐analyses in the field of fisheries. Here, we provide the necessary background for readers, authors and reviewers, including a brief history of the use of meta‐analysis in fisheries, an overview of common model types and distinctions, and examples of different goals that can be achieved using meta‐analysis. We outline the primary challenges in implementing meta‐analyses, including difficulties in discriminating between alternative hypotheses that can explain the data with equal plausibility, the importance of validating results using multiple lines of evidence, the trade‐off between complexity and sample size and problems associated with the use of model output. For each of these challenges, we also provide suggestions, such as the use of propensity scores for dealing with selection bias and the use of covariates to control for confounding effects. These challenges are then illustrated with examples from diverse subfields of fisheries, including (i) the analysis of the stock–recruit relationship, (ii) fisheries management, rebuilding and population viability, (iii) habitat‐specific vital rates, (iv) life‐history theory and (v) the evaluation of marine reserves. We conclude with our reasons for believing that meta‐analysis will continue to grow in importance for these and many other research goals in fisheries science and argue that standards of practice are therefore essential.  相似文献   
94.
LED激发光源叶绿素荧光参数在线监控系统   总被引:3,自引:1,他引:2  
研究设计了一种基于MINIPAM荧光仪调制脉冲式荧光检测技术的LED阵列输出光强叶绿素荧光参数在线监控系统。该系统利用可编程电源为LED列阵提供恒流输出驱动,利用LED列阵作为激发叶绿素产生荧光的光化光,利用MINIPAM荧光仪对植物光系统II的稳态荧光Fs、光适应下最大荧光Fm'进行检测,并结合系统传感器对环境温度、光合有效辐射PAR等植物环境因子的测量,综合分析环境因素对实际量子效率ΦpsII等参数的影响。系统通过串口与上位机通信,上位机可利用DELPHI7语言编制的监控软件对植物光适应下的荧光参数进行实时在线监控。试验表明,与传统的试验方法相比该系统具有精度高、应用范围广等优点,是一种具有广泛应用前景的实时光合能力测量与控制仪器。  相似文献   
95.
Objective – To describe the use of IV and oral mycophenolate mofetil (MMF) as adjunctive therapy in 3 dogs with severe generalized myasthenia gravis.
Case Series Summary – Three dogs suffering from severe generalized myasthenia gravis as confirmed by acetylcholine antibody titers were treated with MMF as part of their treatment regimens. All 3 dogs had radiographic evidence of megaesophagus and suffered from severe regurgitation. Each dog was initially treated with pyridostigmine and supportive agents. When clinical remission was not achieved, IV MMF was administered to all dogs. Signs of clinical remission were apparent within 48 hours and all dogs were later maintained on oral MMF following resolution of regurgitation.
New or Unique Information Provided – This is the first report of the use of IV MMF as adjunctive treatment in dogs with severe generalized myasthenia gravis. Outcome was favorable in all 3 dogs and no adverse effects were noted from the MMF.  相似文献   
96.
97.
Detection, genetic characterization, and control of bovine viral diarrhea virus (BVDV) disease in a large commercial dairy herd is reported. Precolostral BVDV serum antibody was detected in 5.3% (12/226) of newborn calves before the test and removal of persistently infected (PI) animals and in 0.4% (2/450) of newborn calves after the removal of PI heifers.  相似文献   
98.
Two experimental parainfluenza type 3 virus (PI3V) challenge studies were undertaken to evaluate the efficacy of a single intranasal dose of an attenuated live vaccine containing modified live bovine respiratory syncytial virus (BRSV) and temperature-sensitive PI3V in 3-week-old calves. In the first study, vaccine efficacy was evaluated in colostrum deprived calves. Nasal shedding of PI3V was highly significantly reduced in vaccinated calves challenged 10 days or 21 days after vaccination. In the second study, vaccine efficacy was assessed in calves with maternal antibodies against PI3V by challenge 66 days post-vaccination. Vaccination also significantly reduced PI3V excretion after challenge in this study. In both studies, clinical signs after challenge were very mild and were not different between vaccinated and control calves.  相似文献   
99.
Bottom trawl fishing is a controversial activity. It yields about a quarter of the world's wild seafood, but also has impacts on the marine environment. Recent advances have quantified and improved understanding of large‐scale impacts of trawling on the seabed. However, such information needs to be coupled with distributions of benthic invertebrates (benthos) to assess whether these populations are being sustained under current trawling regimes. This study collated data from 13 diverse regions of the globe spanning four continents. Within each region, we combined trawl intensity distributions and predicted abundance distributions of benthos groups with impact and recovery parameters for taxonomic classes in a risk assessment model to estimate benthos status. The exposure of 220 predicted benthos‐group distributions to trawling intensity (as swept area ratio) ranged between 0% and 210% (mean = 37%) of abundance. However, benthos status, an indicator of the depleted abundance under chronic trawling pressure as a proportion of untrawled state, ranged between 0.86 and 1 (mean = 0.99), with 78% of benthos groups > 0.95. Mean benthos status was lowest in regions of Europe and Africa, and for taxonomic classes Bivalvia and Gastropoda. Our results demonstrate that while spatial overlap studies can help infer general patterns of potential risk, actual risks cannot be evaluated without using an assessment model that incorporates trawl impact and recovery metrics. These quantitative outputs are essential for sustainability assessments, and together with reference points and thresholds, can help managers ensure use of the marine environment is sustainable under the ecosystem approach to management.  相似文献   
100.
Farmer-to-farmer outreach was used within a targeted watershed to promote the installation of conservation buffers. In this program called “FarmLink”, four farmers/landowners were employed part-time as “advisors” and trained by University of Nebraska-Lincoln Extension, Natural Resources Conservation Service, and Natural Resources District personnel. Topics included basic buffer design and benefits, availability of incentive programs, and sales techniques. These individuals then contacted their neighbors to explain the need for and benefits of buffers and other conservation practices. In early 2003, 42 landowners were contacted, leading to contracts for the establishment of 16 separate conservation practices on 24.8 ha (61.3 acres) of farmland. These included just over 8 ha (20 acres) of grassed waterways or similar plantings and 14 ha (35 acres) of streamside buffers. In addition, because of information received in the training sessions, one of the advisors installed 1.7 ha (4.3 acres) of streamside buffers, 0.45 ha (1.1 acres) of grassed waterways, and 2.0 ha (5.0 acres) of grasses and forbs on his own land. During these contacts, it became apparent that: (1) many farmers and landowners were not familiar with the multitude of programs available to assist with the installation and maintenance of conservation practices; and (2) landowners generally appreciated the personal touch of someone coming out to talk directly to them, pointing out specific areas on their land where conservation practices could best be implemented, discussing available compensation programs, and describing management needed to help ensure practice success. Although one-to-one contacts cannot be used in all cases, it was demonstrated to be effective in this watershed.  相似文献   
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