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Abstract – Foraging juvenile fish with relatively high food demands are usually vulnerable to various aquatic and avian predators. To compromise between foraging and antipredator activity, they need exact and reliable information about current predation risk. Among direct predator-induced cues, visual and olfactory signals are considered to be most important. Food intake rates and prey-size selectivity of laboratory-reared, naive young-of-the-year (YOY) perch, Perca fluviatilis , were studied in experiments with Daphnia magna of two size classes: 2.8 and 1.3 mm as prey and northern pike, Esox lucius , as predator. Neither total intake rate nor prey-size selectivity was modified by predator kairomones alone (water from an aquarium with a pike was pumped into the test aquaria) under daylight conditions. Visual presentation of pike reduced total food intake by perch. This effect was significantly more pronounced (synergistic) when visual and olfactory cues were presented simultaneously to foraging perch. Moreover, the combination of cues caused a significant shift in prey-size selection, expressed as a reduced proportion of large prey in the diet. Our observations demonstrate that predator-induced olfactory cues alone are less important modifiers of the feeding behaviour of naive YOY perch than visual cues under daylight conditions. However, pike odour acts as a modulatory stimulus enhancing the effects of visual cues, which trigger an innate response in perch. 相似文献
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评价适合选育加工型马铃薯品种的杂交组合 总被引:1,自引:0,他引:1
中国马铃薯的种植面积和产量均占世界首位,随着人们生活水平的提高和饮食结构的改善,以及外资企业在中国的纷纷建厂,对食品加工型马铃薯品种的市场需求日益增加,食品加工型马铃薯品种的培育已成为当务之急。本文根据食品加工型马铃薯品种的6项选育指标(炸制品质、薯形、产量、大中薯率、抗病性、熟期),对14个马铃薯杂交组合进行单个指标的评价和组合的级别评价,最终确定组合F81109×B5141-6、B5141-6×F58050、F67128×F61101、F49013×F61101、F71002×F59103可作为选育食品加工型马铃薯品种比较有前景的杂交组合。 相似文献
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Gülşen Sertkaya Marta Martini Paolo Ermacora Rita Musetti Ruggero Osler 《Phytoparasitica》2005,33(4):380-390
During the late summer-early autumn of 2002, surveys were carried out in Turkey to determine the presence of phytoplasma diseases
in fruit trees. Phytoplasmas were detected and characterized by PCR-RFLP analysis and TEM technique in stone fruit and pear
trees in the eastern Mediterranean region of the country. Six out of 24 samples, including almond, apricot, peach, pear and
plum, gave positive results in PCR assays. RFLP analysis usingSspI andBsaAI enzymes of PCR products obtained with primer pair f01/r01 enabled identification of the phytoplasmas involved in the diseases.
Stone fruit trees, including a local apricot variety (‘Sakıt’) and a pear sample, were found to be infected with European
stone fruit yellows (ESFY, 16SrX-B) and pear decline (PD, 16SrX-C) phytoplasmas, respectively. This is the first report in
Turkey of PD phytoplasma infecting pear and of ESFY phytoplasma infecting almond, apricot, myrobalan plum and peach; ESFY
phytoplasma infecting Japanese plum was previously reported.
http://www.phytoparasitica.org posting July 21, 2005. 相似文献
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The interactive effects of rooting volume and nutrient availability in a skeletal soil medium designed to meet street tree and pavement needs were observed in a containerized experiment. Benjamin fig (Ficus benjamina L.) was grown in a stone-soil blended skeletal soil material (CU-Soil™) and compared to a loam soil. The same topsoil used as the soil component in the skeletal soil material was used as the sole component in the comparison soil-only treatment.Plants grown in the skeletal soil material had reduced leaf tissue N content and depressed growth compared with plants grown in non-diluted soil. No other mineral deficiencies were found. Leaf number, chlorophyll concentration, shoot weight, and root characteristics were all affected.Reduced growth from soil dilution could be offset by the provision of an enlarged rooting volume for root development. Large containers of skeletal soil were observed to have smaller root systems compared to equivalent net volumes of loam soil at the first two harvest dates of the study. By the end of the study, the large containers of skeletal soil were observed to have developed larger root systems compared to equivalent net volumes of loam soil; resulting in comparable leaf N levels and total plant dry matter. Plants in skeletal soil had lower shoot: root ratios at the end of the study. Investing resources to further root growth in times of nutrient shortages is a probable plant reaction as evidenced by differences in specific root length between treatments. The study allowed a method for directly partitioning the containerization effect by having equivalent amounts of soil over two volumes. 相似文献
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转基因食品的检测方法 总被引:8,自引:0,他引:8
目前,世界各国对转基因食品的检测主要从外源DNA和蛋白两种生物大分子入手,所广泛采用的方法有聚合酶链式反应(PCR)、生物芯片技术(Biochips)、酶联免疫吸附测定(ELISA)和侧流技术(Lateral Flow)。本文综述了各种方法的原理以及这些方法用于检测转基因食品时的优缺点。 相似文献
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采用22种限制性内切酶分析了三江白猪线粒体DNA的多态性。结果表明:在60头个体中检出30种限制性态型.归结为7种基因单倍型;其间的差异来自少数限制性位点的突变。单倍型间平均遗传距离为0.35%,群体遗传多态程度为0.044%。三江白猪遗传多样性非常贫乏,说明三江白猪与地方种猪起源于一个共同祖先,在品种形成早期受到创立者效应的制约。 相似文献