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61.
A radiologic and tomographic study was made of the cranioencephalic topography of canary goats of medium weight and size. In a first step, the exocranialis references corresponding to an axis designed at the level of the meatus acusticus externus and parallel to the basicranial axis were anatomically and radiologically defined. Conventional stereotaxic techniques were then used to reach the standard position of the head in order to obtain macroscopical cross sections at different levels perpendicular to the base of the cranium. In a second step, a tomographic study was made to confirm the design of the axis.  相似文献   
62.
青杨楔天牛对杨树危害的研究   总被引:3,自引:0,他引:3       下载免费PDF全文
定量研究青杨楔天牛对白城杨的危害表明:寄生直径小于0.5cm的枝梢,侵入初期92.2%枯萎风折;寄生直径小于1.0cm的枝梢,侵入后期11.5%风折,成虫出孔后87.4%的寄生枝梢干枯风折。青杨楔天牛形成的虫瘿对枝梢的连年生长量影响时间长,影响量大。每主梢有1只和2只虫瘿其第1、2、3年连年生长量分别减少28.3%、16.4%、9.8%和42.0%、28.9%、17.2%。每侧枝上有1只和2只虫瘿其第1、2、3年连年生长量分别减少21.7%、12.1%、6.3%和34.8%、22.8%、13.8%。  相似文献   
63.
The spatial and temporal evolution of soil water content (θ) in Quercus ilex dehesas has been investigated to determine how trees modify the soil water dynamics and the nature of tree-grass interactions in terms of soil water use in these ecosystems. Soil physical parameters and θ were measured at different distances from the tree trunk (2–30 m) in the upper 300 cm of soil. θ was measured monthly by TDR during 2002–2005. Tree water potential was determined during the summers of 2004 and 2005. At deeper soil layers, mean θ values were higher beyond than beneath tree canopy during dry periods. θ depletion beyond tree canopy continued even in summer, when herbaceous plants dried up, suggesting that trees uptake water from the whole inter-tree space. Results have shown a high dependence of trees on deep water reserves throughout late spring and summer, which helps to avoid competition for water with herbaceous vegetation.  相似文献   
64.
1994年,吉林省日本松干蚧分布面积256.7hm^2,到2002年,分布面积达到10867.2hm^2,呈快速扩散蔓延趋势。日本松干阶主要治理对策是:在疫情发生区,以营林抚育、封山育林、生物防治为主,以化学防治为辅,全力封锁控制疫情,严防继续扩散蔓延,努力减轻危害损失,对无防治前途的疫林进行有计划地砍伐更新;在疫情保护区,通过隔离带和检疫检查站建设,阻断日本松干蚧的自然和人为传播。  相似文献   
65.
高性能耐磨纸的研究   总被引:4,自引:0,他引:4  
探索了不同的涂布量、胶粘剂的种类和用量对耐磨纸的耐磨转数、吸水高度和湿强度的影响,通过优化涂布工艺配方使耐磨纸的耐磨转数提高到7000转以上。  相似文献   
66.
Godefroid  M.  Morente  M.  Schartel  T.  Cornara  D.  Purcell  A.  Gallego  D.  Moreno  A.  Pereira  J. A.  Fereres  A. 《Journal of pest science》2022,95(2):855-868

The bacterium Xylella fastidiosa (Xf) is an invasive insect-borne pathogen, which causes lethal diseases to important crops including olives, citrus, almonds and grapes as well as numerous forest, ornamental, and uncultivated plants. Outbreaks of Xf-related plant diseases are currently occurring in the Mediterranean region, causing substantial losses to various agricultural sectors. Several models have recently been published to identify which regions are at highest risk in Europe; however, such models did not consider the insect vectors, which constitute the key driver of short-range Xf spread. We fitted bioclimatic species distribution models to depict the macroclimatic preferences of the meadow spittlebug Philaenus spumarius L. (1978) (Hemiptera: Aphrophoridae), the major epidemiologically relevant vector currently responsible for Xf spread in the Europe. Many regions of Western Europe and Mediterranean basin are predicted by models as highly climatically suitable for this vector, including all regions where severe Xf have occurred so far. Conversely, the driest and warmest areas of the Mediterranean basin are predicted as little suitable for P. spumarius. Models forecast that agricultural-important parts of the southern Mediterranean area might experience a substantial decrease in climatic suitability for P. spumarius by the period 2040–2060. Areas predicted as highly suitable just for the bacterium but not optimal for this vector are apparently still free of severe Xf outbreaks, suggesting that climate tolerances of P. spumarius might partly explain the current spatial pattern of Xf outbreaks in Europe and should always be considered in further risk assessments.

  相似文献   
67.
Salmonella enterica serovar typhimurium (S. typhimurium) is one of the most frequent Salmonella serotypes isolated from European pigs. Despite the advances in understanding the mechanisms involved in host–pathogen interactions and host cell responses to S. typhimurium, the global change that occurs in naturally exposed populations has been poorly characterized. Here, we present a proteomics study on intestinal mucosa of pigs naturally infected with S. typhimurium, in order to better understand the pathogenesis of salmonellosis and the pathways which might be affected after infection. Samples were analyzed by 2D-DIGE and 44 different proteins exhibited statistically significant differences. The data set was analyzed by employing the Ingenuity Pathway Analysis and the physiological function most significantly perturbed were immunological and infectious disease, cellular assembly and organization and metabolism. The pathways implicated in the porcine immune response to S. typhimurium were gluconeogenesis and Rho GDI/RhoA signaling, and our results suggest that keratins and the intermediate filaments could play an important role in the damage of the mucosa and in the success of infection. The role of these findings in salmonellosis has been discussed, as well as the importance of analyzing naturally infected animals to have a complete picture of the infection. Also, we compared the results found in this work with those obtained in a similar study using experimentally infected animals.  相似文献   
68.
An outbreak of human leishmaniosis was confirmed in the southwest of the province of Madrid, Spain, between July 2009 and December 2012. Incidence of Leishmania infection in dogs was unchanged in this period, prompting a search for alternative sylvatic infection reservoirs. We evaluated exposure to Leishmania in serum samples from animals in the area with an indirect immunofluorescence test (IFAT). Using promastigotes from six culture passages and a 1/25 threshold titer, we found anti-Leishmania infantum seroreactivity in 9.3% of cats (4 of 43), 45.7% of rabbits (16/35) and 74.1% of hares (63/85). Use of promastigotes from >10 in vitro passages resulted in a notably IFAT lower titer, suggesting antigenic changes during extended culture. Postmortem inspection of seropositive animals showed no clinical signs of infection. The results clearly suggest that asymptomatic hares were the main reservoir in the outbreak, and corroborate IFAT as a sensitive serological surveillance method to detect such cryptic Leishmania infections.  相似文献   
69.
This study reports a functional characterization of a limited segment (QTL) of sheep chromosome 12 associated with resistance to the abomasal nematode Haemonchus contortus. The first objective was to validate the identified QTL through the comparison of genetically susceptible (N) and resistant (R) sheep produced from Martinik × Romane back-cross sheep. The R and N genotype groups were then experimentally infected with 10 000 H. contortus larvae and measured for FEC (every three days from 18 to 30 days post-challenge), haematocrit, worm burden and fertility. Significant differences in FEC and haematocrit drop were found between R and N sheep. In addition, the female worms recovered from R sheep were less fecund. The second step of the characterization was to investigate functional mechanisms associated with the QTL, thanks to a gene expression analysis performed on the abomasal mucosa and the abomasal lymph node. The gene expression level of a candidate gene lying within the QTL region (PAPP-A2) was measured. In addition, putative interactions between the chromosome segment under study and the top ten differentially expressed genes between resistant MBB and susceptible RMN sheep highlighted in a previous microarray experiment were investigated. We found an induction of Th-2 related cytokine genes expression in the abomasal mucosa of R sheep. Down-regulation of the PAPP-A2 gene expression was observed between naïve and challenged sheep although no differential expression was recorded between challenged R and N sheep. The genotyping of this limited region should contribute to the ability to predict the intrinsic resistance level of sheep.  相似文献   
70.
以相关文献中药剂抑菌试验的结果为参考,选用7种常见杀菌剂,在天津汉沽地区针对烂皮型溃疡病较重的毛白杨和水泡型溃疡病较重的107杨开展药剂防治试验,防治前后分别进行病情调查,并对调查结果和防治成本进行了统计分析。防效分析结果表明:腐烂净(腐殖酸铜)、轮腐净(甲硫·福美胂)对烂皮型溃疡病防效最好,病情抑制率依次为75.33%,70.89%,且二者防效无显著差异(P0.05);80%多菌灵可湿性粉剂和轮腐净(甲硫·福美胂)对水泡型溃疡病防效最好,病情抑制率依次为72.00%,68.44%,且二者防效无显著差异(P0.05)。防治成本分析表明:不包含病斑刮除的人工费用(80元·百株-1),腐烂净(腐殖酸铜)和轮腐净(甲硫·福美胂)成本最低,分别为44.6元·百株-1和51.5元·百株-1,80%多菌灵可湿性粉剂成本较高,达到73.5元·百株-1。综合考虑防治效果和经济效益,轮腐净(甲硫·福美胂)是防治两种类型溃疡病的最优选择。  相似文献   
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