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91.
    
The objective of this study was to assess the effects of fishmeal (FM) replacement with 0, 350 or 700 g/kg soybean meal (SBM) in combination with the supplementation of lactic acid (LA; 0, 10 or 20 g/kg) in the diets of juvenile beluga sturgeon (Huso huso; 700 ± 30 g). Nine isonitrogenous (400 g/kg protein) and isoenergetic (18 MJ/kg) diets were fed to beluga ad libitum, three times a day, for 60 days. The results showed that replacing FM with SBM without LA significantly reduced fish growth; on the other hand, LA supplementation had positive effects on fish fed diets that FM was replaced by SBM (< .05). Increasing SBM in the diet altered the fatty acid profiles of the fish, reducing long‐chain polyunsaturated fatty acids and the n‐3/n‐6 fatty acids. High amounts of SBM (700 g/kg) caused reductions in the haematocrit, glucose and cholesterol levels in the blood (< .05). In addition, the digestibility of protein, fat, dry matter and phosphorus was reduced when replacing FM with SBM, however, adding LA to the diets increased fish performance (< .05), and this improvement was sharper in 2% LA groups. The number of LA bacteria increased significantly with the dietary supplementation of LA (< .05). Based on these results, replacing 350 g/kg of FM with SBM and adding 20 g/kg LA to their feed do not negatively affect the biological and physiological indices of beluga.  相似文献   
92.
汪菁 《湖南农机》2013,(3):174-175,184
随着我国经济的快速发展,贫困问题也日益凸显。近年来,国家加大扶贫力度,大力推进小额信贷在农村的发展。农村信用社作为正规金融推进小额信贷发展的主力军,在推进小额信贷业务过程中取得了一定的成效,但也面临了一系列的问题。文章阐述农村信用社小额信贷业务的发展现状,深入剖析其在发展过程中面临的问题,并提出相应的对策建议。  相似文献   
93.
本文首先介绍了山西省中药材生产机械化发展的现状,根据近年调研和统计数据,从中药材生产机械化各环节发展情况剖析了山西省中药材生产机械化发展中存在的问题。通过对山西省中药材生产大县、合作社、农户、机具生产厂商的调研和分析,提出了针对山西省中药材机械化发展的对策及建议,为山西省中药材生产机械化发展提供依据。  相似文献   
94.
A potentially significant cause of damage to grassland soils is compaction of unsaturated soil and poaching of saturated or nearly saturated soil by animal hooves. Damage is caused when an applied stress is in excess of the bearing strength of the soil and results in a loss of soil structure, macroporosity and air or water conductivity. Severely damaged soils can cause reduced grassland productivity and make grazing management very difficult for the farmer. The actual amount of soil damage that can occur during grazing is dependent on the grass cover which acts as a protecting layer, the soil water content and the characteristics of the grazing animal (weight and hoof size). Assuming that the farmer is knowledgeable about the characteristics of the grazing animal and grass cover, it would be very useful for short‐term operational farm planning to be able to predict when soil water contents were likely to be in a critical range with respect to potential hoof damage. In this study soil moisture deficits (SMDs) which can be derived from meteorological forecasts are evaluated for predicting when soil water conditions are likely to lead to hoof damage. Two contrasting Irish grassland soils were analysed using a Hounsfield servo‐mechanical vertical testing machine to simulate static (285.4 N) and dynamic (571 N) hoof loads on the soil over a range of estimated SMDs (0, 5, 10 and 20 mm). The deficits were analysed with respect to the soil volumetric water content, compression (displacement) and change in dry bulk density. The SMDs imposed in the laboratory were similar to those under field conditions and thus the methods used in this study are applicable elsewhere. The change in dry bulk density following loading (0.2–0.7 g/cm3) was linearly related to SMD (R2 ranged from 0.90 to 0.99), leading to the conclusion that a forecast of SMD can be used to predict when grassland soils are likely to be at risk of damage from grazing.  相似文献   
95.
Internet listservers, a freely available resource on the Internet for anyone who can send and receive emails, provide a means for professionals to communicate and collaborate with each other in the field of soils and sediments. While moderated listservers are highly effective, in terms of quality and participation (activity) level, do not underestimate the knowledge base held within many of the soil and sediment-related listservers. Readers are encouraged to subscribe to those lists which match their own areas of the soil and sediment fields and to become active. Currently, the only listservers dedicated to sediments are of very low activity, with the lowest numbers of subscribers of all listservers surveyed. As a word of caution, Internet listservers are not a primary source of knowledge (in any scientific field), the quality of knowledge exchanged is highly variable, and if not properly managed, can waste time.  相似文献   
96.
机电产品的包装需要耗费大量的原木,对环境造成了极大的影响,也增加了机电产品的生产经营成本。文章从低碳和成本约束的角度,对机电产品包装概念设计的模型进行了分析和探讨。  相似文献   
97.
在新的历史条件下,随着教学改革的深入进行,对教学管理人员素质提出了更高的要求。文章通过分析高校教学管理工作对管理人员在思想政治素质、职业道德素质、科学文化素质、身心素质等方面的要求,针对高校教学管理人员素质的现状和问题,提出提高高校教学管理人员素质的对策。  相似文献   
98.
99.
 We studied the relationship between urease activity (UA) and soil organic matter (SOM), microbial biomass N (Nbiom) content, and urea-N fertilizer assimilation by maize in a Dark Red Latosol (Typic Haplustox) cultivated for 9 years under no-tillage (NT), tillage with a disc plough (DP), and tillage with a moldboard plough (MP). Two soil depths were sampled (0–7.5 cm and 7.5–15 cm) at 4 different times during the crop cycle. Urea was applied at four different rates, ranging from 0 to 240 kg N ha–1. The levels of fertilizer N did not affect the UA, SOM content, and Nbiom content. No significant difference between the treatments (NT, DP, and MP) was observed for SOM during the experiment, probably because the major part of the SOM was in recalcitrant pools, since the area was previously cultivated (conventional tillage) for 20 years. The Nbiom content explained 97% and 69% of the variation in UA in the upper and deeper soil layer, respectively. UA and biomass N were significantly higher in the NT system compared to the DP and MP systems. The highest maize productivity and urea-N recovery was also observed for the NT system. We observed that the increase in urea-N losses under NT, possibly as a consequence of a higher UA, was compensated for by the increase in N immobilized in the biomass. Received: 2 July 1999  相似文献   
100.
混合土料是由粗细土颗粒组成的土。作者对混合土料、均匀粗粒土及纯细烂土的颗粒组成与工程性质进行了对比分析。结果表明,混合土料是介于均匀粗粒土和纯细粒土之间的土,它的工程性质有别于均匀粗粒土和纯细粒土,有必要对其单独命名,这为混合土的合理定位与专门研究提供了基础。  相似文献   
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