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991.
鹦鹉饲养过程中常见的细菌病主要包括大肠杆菌病、传染性鼻炎、禽霍乱、传染性眼炎等。通过对鹦鹉常见疫病的病原菌进行分离鉴定,探讨了鹦鹉常见细菌病的主要致病菌的类型以及行之有效的防治方案。试验结果表明,引起鹦鹉常见细菌病的主要致病菌有大肠杆菌、鸡副嗜血杆菌、多杀性巴氏杆菌、金黄色葡萄球菌和耐药性链球菌。 相似文献
992.
以黄河兰州段11个不同采样点3种多环芳烃的临测浓度及其对6~38种水生生物的LC50为基础资料,分别应用商值法、概率密度函数重叠面积和联合概率曲线3种风险浮价方法对黄河兰州段苯并(a)芘、荧蒽、芘的生态风险进行了评价.结果表明:黄河兰州段3种PAHs残留具有一定的生态风险.其中低暴露风险条件下(受威胁生物不超过1%),... 相似文献
993.
Thomas Weinzierl Jan Wehberg Jürgen Bhner Olaf Conrad 《Land Degradation \u0026amp; Development》2016,27(2):281-294
The Okavango catchment in southern Africa is subject to environmental as well as socio‐economic transformation processes such as population growth and climate change. The degradation of soil and vegetation by deforestation and overgrazing is one of the downsides of this development, reducing the capacity of the land to provide ecosystem functions and services. In this study, climate simulations are brought together with secondary socioeconomic, pedologic and remote‐sensing data in a GIS‐based assessment of the factors commonly associated with land degradation risk. A high resolution overview is provided for decision‐makers and stakeholders in the region by identifying priority intervention areas where a long‐term decline in ecosystem function and land productivity is most likely to occur. The approach combines 19 risk factors into seven individual ratings for topography, landcover, soil, demography, infrastructure, livestock pressure and climate. These ratings are then weighted and combined into an integrated degradation risk index (DRI). The results show that the land degradation risk is quite heterogeneously distributed in the study area and caused by different factors. Three hot‐spots are identified and compared, one of which is in the far northwestern part of the catchment, one around the local center Rundu and one on the outskirts of the Okavango Delta. We conclude that the approach is suitable to give an overview on degradation risk in the study area, although the classification process is a crucial procedure that should be standardized for further research. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
994.
WANG Fang ZHENG Xiaoxian HU Yang LIU Bo . School of Forest Beijing Forestry University Beijing P. R. China . Municipal Bureau of L scape Forestry of Dongping County Dongping 《中国林业科技(英文版)》2011,(3):31-38
For the healthy management of plantation, a health assessment indicator system was designed at forest stand scale for the larch plantation in Jin'ouling Forest Farm, Wangqing Forestry Bureau, Jilin Province. The system consisted of 3 categories—forest structure, external interferences and management objectives, with 15 indicators. The results showed that: 1) the assessment indicator system was scientific and rational for different age groups of larch plantations; 2) both the half-mature larch plantation and... 相似文献
995.
Simon Bilodeau-Gauthier Daniel Houle Christian GagnonBenoît Côté Christian Messier 《Forest Ecology and Management》2011,261(1):95-104
Partitioning of elements in tree xylem is being increasingly studied, as it suggests that elements are potentially mobile within the xylem long after their uptake. A recent study revealed that only the most mobile xylem fraction (water-soluble) of base cations (calcium [Ca], magnesium [Mg], and potassium [K]) increased at higher soil acidity, while the two mobile fractions (water- and acid-soluble) of acidic metals—potentially phytotoxic aluminium (Al), cadmium (Cd) and manganese (Mn)—were significantly enhanced on very acid soils. The current paper presents an investigation of soil-wood chemistry relationships with basal area tree growth. It was hypothesized that the growth of sugar maple would be reduced by low base cation and high acidic metal concentrations in the xylem mobile fractions. Sugar maple trees (n = 55) from six watersheds in southern Quebec, Canada were analysed by sequential chemical extractions for the water-soluble, acid-soluble and residual fractions of base cations (Ca, K, Mg) and acidic metals (Al, Cd, Mn) in xylem. Generally, tree growth was positively correlated to concentrations of base cations in wood (ρ = 0.27-0.50) and soil (ρ = 0.41-0.67), and negatively correlated to concentrations of acidic metals in wood (ρ = −0.33 to −0.52) and soil (ρ = −0.67). However, these relations differed depending on the element fraction considered. Water- and acid-soluble xylem concentrations of base cations and Al were among the best predictors of growth trends (R2 = 0.46-0.51). The relationship between acidic metals and tree growth is further discussed. 相似文献
996.
在工程实践中,承包商风险管理能力的高低将直接影响着工程风险的高低,作为业主在进行风险评估时不应忽略承包商风险管理能力对风险高低的影响。为此提出承包商风险管理能力指数概念,并构建基于风险自然属性评估和风险管理能力评估相结合的工程项目风险综合评估模型,以完善和充实风险等级评估的内涵。 相似文献
997.
998.
999.
如何监控施工质量和施工安全 总被引:1,自引:0,他引:1
施工质量和工程建设的安全始终贯穿于工程建设的全过程,如何监控和保证质量及施工安全,是每个参与工程建设和管理人员的职责和义务;特别是工程监理人员更要加强重视,只有加强了施工现场管理和监控,才能有效的控制施工质量和预防事故的发生。 相似文献
1000.
地质钻探施工是一项复杂的系统工程,涉及到安全、人力、设备、质量、经济效益等;尤其是钻孔施工中的安全和生产管理,是钻探生产管理的主要任务。 相似文献