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51.
A literature survey was conducted to determine the amphibian diversity and distribution in Brazilian Amazonia. Patterns of endemisms and similarity of fauna between localities were also addressed. Twenty-eight inventories were found for the region, the majority localized in areas with easier access by road or river. A minimum of 163 amphibian species was recorded for Brazilian Amazonia. Although many species are endemic to the Amazonian lowlands as an entity, the patterns of species uniqueness among sites suggested low endemic distribution within the lowlands of the Amazon Basin. The mean similarity between localities varied from low to intermediate (mean=0.40), indicating that the Brazilian Amazonia is characterized by distinctive assemblages of amphibians throughout its extension. Localities further apart had lower similarity. No threatened species were recorded. These results contribute to determine priority areas for new inventories and establishment of conservation units. We suggest that areas next to the Amazon deforestation frontier should be prioritized for new studies due to the high rate of alteration and potential loss of species. Additionally, studies on amphibian population dynamics are few in Brazilian Amazonia and more of them should be emphasized to help to draw a better picture of the status of amphibians in this region. 相似文献
52.
Reserve corridors in production forestry landscapes are frequently concentrated in riparian areas. This study describes the numerical response of ground-dwelling beetles to increasing distance from streams, with the aim of evaluating the effectiveness of such a bias in reserve allocation. Patterns in abundance and diversity of epigaeic beetles were quantified at four first order streams in wet eucalypt forest in Tasmania, Australia. The depth and pattern of beetles’ riparian response varied between streams. Commonly trapped beetles were less abundant near to three of the four streams, and the numerical response model differed in each case. Species richness of common beetles was also lower near one of the streams. Pooled abundance and richness of rare species did not vary in response to the riparian-upslope transition. No riparian or upslope specialist species were identified among the most commonly collected species. Compared to upslope habitat, the riparian-upslope transition encompassed greater variability in species composition without actually increasing overall richness. The study findings demonstrate the need for ecosystem-specific data to optimize reserve placement, since the results were not predicted from general vegetation patterns, ecological theory, or the widely held assumption that riparian areas support greater abundance and diversity of organisms than adjacent upslope areas. Reserves encompassing more upslope habitat are recommended to complement those located in riparian areas. 相似文献
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We sampled saproxylic beetles using trunk window traps in two birch-dominated forests in Finland during 1990-1999. The sampling scheme, 10 traps attached to living fruiting bodies of Fomes fomentarius growing on dead birches, remained unchanged in both forests throughout the study period. Beetles belonging to 32 selected families were identified every year, whereas all species were identified during the last 4 years. Total number of identified individuals was 40,294 and number of species 583, of which 258 were saproxylic (dependent on dead wood). Species richness of rare and threatened saproxylic beetles in the samples varied a lot between the years and did not fluctuate synchronously between the forests. Variation between years was smaller when all saproxylic species were pooled together and some abundant species fluctuated synchronously in the two forests. Similarity indices and DCA-ordination did not generally suggest decreasing similarity between samples with increasing temporal isolation. Incidence-based similarities of common saproxylic species within and between forests and years were high (means 0.7-0.8), whereas those of rare saproxylics were roughly 50% smaller and much more variable. More than 75% of the common saproxylic species found during the entire 10-year period were detected already after 3 years of sampling but accumulation of rare and threatened species was much slower. Our results suggest that: (1) occurrence of rare and threatened species in samples is much less predictable than that of common species and, e.g. reserve selection based on rarities should be made cautiously; (2) estimation of total number of threatened species in a forest is very difficult, because such species accumulate slowly in the samples; (3) samples from different years can be comparable in certain cases. 相似文献
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为了寻求一种安全有效的方法防治由意大利青霉(Penicillium italicum)引起的柑橘青霉病,该研究分析了碳酸铵作为通常认为安全的药剂抑制意大利青霉生长的可能作用机制及对脐橙、皇帝柑、沃柑3种不同类型柑橘贮藏品质的影响。结果表明,碳酸铵能抑制意大利青霉孢子萌发和菌丝生长,且呈现剂量依赖效应,在质量浓度分别为 0.4 g/L和0.8 g/L时可完全抑制孢子萌发和菌丝生长。结构观察表明,碳酸铵引起菌丝生长节点稀疏和分支减少;超微结构观察发现菌丝严重皱缩,菌丝线粒体结构异常。生理生化分析表明,碳酸铵处理,引起线粒体的钠/钾离子ATP酶(Na+/ K+-ATPase)、钙离子ATP酶(Ca2+-ATPase)和镁离子ATP酶(Mg2+-ATPase)活性下降,导致还原型谷胱甘肽(Reduced Glutathione,GSH)含量及谷胱甘肽还原酶(Glutathione Reductase,GR)活性降低,活性氧清除体系超氧化物歧化酶(Superoxide Dismutase,SOD)、过氧化氢酶(Catalase,CAT)、过氧化物酶(Peroxidase,POD)活性紊乱,促进H2O2积累。添加活性氧清除剂半胱氨酸(Cysteine,Cys)能部分恢复碳酸铵处理的病菌孢子萌发。活体接种表明,16 g/L碳酸铵处理显著减小了柑橘果实接种意大利青霉的病斑直径(P<0.05),减轻果实发病。碳酸铵处理能降低3种类型柑橘果实自然发病率,且对果实失重率、色泽、可溶性固形物、可滴定酸、维生素C、还原糖含量无不良影响。结果表明,碳酸铵通过损伤意大利青霉菌丝线粒体结构和功能,促进活性氧积累来发挥抗真菌活性,碳酸铵可以作为杀菌剂的绿色有效替代方法,研究结果为碳酸铵防治柑橘果实采后腐烂提供参考。 相似文献
55.
天然甜槠林物种多样性的研究 总被引:1,自引:0,他引:1
本文运用物种多样性、物种丰富度、物种均匀度等分析方法对福建省周宁县天然甜槠林的群落组成进行研究。结果表明:甜槠群落物种多样性指数和均匀度值均较大,群落结构复杂、物种丰富。研究结果为保护该地域森林植被提供了理论依据。 相似文献
56.
Non-native pollinator species are now widely utilized to facilitate pollination of agricultural crops. Evaluation of the ecological risk of alien pollinators is necessary because they could have a large impact on native ecosystems through disturbing native plant-pollinator interactions. We conducted a greenhouse experiment to examine the impact of the non-native commercialized European bumblebees, Bombus terrestris, on the pollination success of seven Japanese bumblebee-pollinated plant species. Plants were exposed to three groups of bumblebees: native bumblebee(s) only (NATIVE treatment); the alien bee only (ALIEN) and a mix of the two (MIX). ALIEN treatment had negative effects on fruitset and/or fruit quality of five plants, including self-incompatible and compatible, herb and woody, and queen- and worker-pollinated species. The negative effects were caused by a decrease in legitimate flower visitation due to (1) physical inaccessibility to nectary in deep-corolla flowers by the alien bee with insufficient tongue length and, (2) biased flower preference between short-corolla flowers. Fruitset tended to decrease drastically for the self-incompatible species while fruit quality decreased moderately for the self-compatible species. Effects of MIX were not intermediate between NATIVE and ALIEN in most plant species, and caused pollination success to vary in an unpredictable manner amongst plant species, probably due to interaction between native and alien bees. This non-linear relationship between plants’ pollination success and the relative density of the alien suggests that the alien bee can disturb pollination of a plant species even when only representing a small fraction of the total pollinator community. 相似文献
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抚顺西排土场矸石山阴坡随着排矸年限的增加,物种多样性发生变化,物种数由初期的4科5种增至后期14科29种。植被由最初的鹅绒藤+豚草+刺蒺藜群落,逐步演变到榆树群落。在阴坡,不同排矸年限的样地,植物群落多样性指数随着排矸时间的延长而增加;物种综合多样性指数、丰富度指数与排矸年限呈显著正相关关系。 相似文献