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51.
我国地域辽阔,但可利用土地资源少,同时由于生产建设和自然灾害等,造成许多优质土地资源损毁。调查清楚土地损毁情况,采取针对性的土地复垦措施,在目前经济发展中显得尤为迫切。以山东某矿区为例,确定了历史遗留损毁土地的划定依据,利用RS与GIS等技术手段对矿区进行地表沉陷预计,用遥感影像提取土地利用变化情况,得到了历史遗留损毁土地的位置、面积和损毁类型等信息,为后期土地复垦与规划提供参考。   相似文献   
52.
Forest losses or gains have long been recognized as critical processes modulating the carbon flux between the biosphere and the atmosphere. Timely, accurate and spatially explicit information on forest disturbance and recovery history is required for assessing the effectiveness of existing forest management. The major objectives of our research focused on testing the mapping efficacy of the vegetation change tracker (VCT) model over a forested area in China. We used a new version of VCT algorithm built upon the Landsat time series stacks (LTSS). The LTSS consisted of yearly image acquisitions to map forest disturbance history from 1987 to 2011 over the Ning-Zhen Mountains, Jiangsu Province of east China. The LTSS consisted of TM and ETM+ scenes with different projections due to distinct data sources (Beijing remote sensing ground station and the USGS EROS Center). The validation results of the disturbance year maps showed that most spatial agreement measures ranged from 70 to 86 %, comparable with the VCT accuracies reported for many places in USA. Very low accuracies were identified in 1995 (38.3 %) and 1992 (56.2 %) in the current analysis. These resulted from the insensitivity of the VCT algorithm to detect low intensity disturbances and also from the mis-registration errors of the image pairs. Major forest disturbance types existing in our study area were identified as agricultural expansion (39.8 %), urbanization (24.9 %), forest management practice (19.3 %), and mining (12.8 %). In general, there was a gradual decreasing trend in forest cover throughout this region, caused principally by China’s economic, demographic, environmental and political policies and decisions, as well as some weather events. While VCT has largely been used to assess long term changes and trends in the USA, it has great potential for assessing landscape level change elsewhere throughout the world.  相似文献   
53.
辉夜姬——日本竹文化的象征   总被引:1,自引:0,他引:1  
《竹取物语》是日本物语文学之"鼻祖",有着浓厚的日本竹文化背景。通过小说中竹文化背景、竹子发光、竹灵信仰、竹工艺文化、三月长大、辉夜姬的光辉、命名竹文化、管弦竹文化、八月十五升月日等方面,揭示日本竹文化内涵,论证了此竹之传奇的主人公辉夜姬业已成为日本竹文化的象征。  相似文献   
54.
Discovering the key genes responsible for deep‐sowing germination is very meaningful to cultivate maize varieties with strong germination ability in soil. In this study, ZmMYB59 gene whose functions remain unknown was successfully cloned. Subcellular localization showed that ZmMYB59 was localized in the nucleus. By analysing cis‐acting elements of its promoter sequence, many elements of MYB binding domain responsive to hormones (particularly gibberellin, GA) were found. On this basis, ZmMYB59 expression in different sowing depths, germination stages, tissues and treatments was analysed by real‐time PCR. ZmMYB59 expression levels in embryos or seedlings were significantly decreased with the increase in sowing depth at 2 days or 4 days after sowing (DAS). Further analysis showed that its expression in mesocotyls was also significantly downregulated with the increase in sowing depth at both 6 DAS and 8 DAS. Similarly, seed soaking with 10‐5 M GA3 inhibited ZmMYB59 expression in mesocotyls at 3 DAS. These results suggest that ZmMYB59 may play a negative regulatory role in seed germination in deep soil and the regulation is involved in GA signalling pathway.  相似文献   
55.
萘醌类化合物普遍被报道具备较好的抗肿瘤能力。以1,5-二羟基萘为原料,经五步反应得到了4个末端含有羟基的萘醌类衍生物(6a-d)和1个未含羟基的萘醌类衍生物(6e),并通过质谱和1H NMR进行结构鉴定,采用MTT法评价了5种化合物对人肝癌细胞Hep3B细胞系的生长抑制作用。结果显示取代基末端含羟基的萘醌类衍生物的抗肿瘤活性与碳链长度有密切关系。研究中的6 d对肿癌细胞Hep3B抑制活性最强,IC50为9.1μmol·m L~(-1)。  相似文献   
56.
豆粕是一种优质的植物性蛋白来源,含有丰富的氨基酸,但也含有胰蛋白酶抑制因子、抗原蛋白以及大豆凝集素等抗营养因子,容易引起犊牛消化功能紊乱,造成营养性腹泻,限制了其在犊牛上的使用量。微生物发酵可以改善豆粕的营养价值,使抗营养因子得到充分的降解,生成的小肽和有机酸有利于犊牛消化吸收和肠道健康,进而提高犊牛断奶日增重和免疫能力,降低犊牛的腹泻率和断奶应激。本文综述了豆粕经过发酵后带来营养价值的变化,并就发酵豆粕在犊牛上的应用进行概述,为其今后在犊牛中的应用提供参考。  相似文献   
57.
随着畜禽规模养殖的发展,高度集约化养殖模式将影响畜禽的健康状况、疫病防控和福利水平。一种无接触、无应激的射频识别(Radio Frequency Identifi cation,RFID)技术应运而生,该技术可以在无损状态下采集畜禽的行为、生理生化和养殖环境指标,从而为评估集约化养殖的效果和影响提供基础数据。文章讨论了三种常见类型的RFID系统在畜禽养殖中的应用,系统地比较了各类系统的优缺点及适宜应用场景,进一步提出RFID在畜禽养殖中的未来应用方向,以期为深化畜禽信息采集的研究提供参考。  相似文献   
58.
对灰铸铁的研究现状和生产中的一些新技术做了评述。重点介绍了高强度薄壁灰铸铁的生产现状以及先进的制造工艺和先进的制造手段在灰铸铁生产中应用所取得的技术成果。  相似文献   
59.
We investigated the effects of a dual‐frequency frequency‐sweeping ultrasound (DFFSU) treatment on the functional properties and structure of zein. The solubility of ultrasound‐treated zein proteins increased slightly but significantly as the treatment time increased. The results showed that the DFFSU treatment had an obvious influence on the mean particle size and the size distribution. A significant (P < 0.05) increase in the size of the particles with respect to time was observed after a sonication time of more than 20 min in zein solutions. Differential scanning calorimetry results showed that sonication alters the thermal behavior of zein. Circular dichroism spectra showed a small increase in the percentage of ordered structure elements within the protein molecule. After 60 min of ultrasonication, the percentage of α‐helix structures increased by 0.9%, whereas the percentage of β‐sheets and β‐turns decreased by 0.5%. Microstructural analyses by scanning electron microscopy showed that several microholes appeared in the zein following ultrasonic pretreatment. Under the conditions investigated in this study, DFFSU treatment was found to affect the studied functional properties of the zein protein. This technology could be used to obtain improved functional properties in some protein samples.  相似文献   
60.
In this study, the effects of mixing process parameters (degree of vacuum, water addition, and mixing time under vacuum) on the cooking and sensory quality properties of Chinese white noodles were investigated by using one commercial‐scale noodle production line and one typical commercial wheat flour. Noodle appearance, firmness, elasticity, smoothness, and total quality scores were significantly improved as the degree of vacuum increased from 0 to 0.06 MPa, although lower sensory scores and larger cooking losses occurred when noodles were mixed at 0.08 MPa. Noodles with a water addition of 35% had the highest total score and the highest scores for each sensory factor. As mixing time increased, the sensory score of cooked noodles increased initially and then decreased. With a mixing time of 7 min, the sensory score was the highest and cooking loss was the lowest. The results of response surface methodology indicated that fresh noodle quality was most affected by the water addition, followed by vacuum degree. Added water was a more important source of variation for appearance, firmness, stickiness, smoothness, total score, and cooking loss than degree of vacuum and mixing time, whereas degree of vacuum was the predominant source of variation for color and elasticity. The interactions between the factors had little effect on sensory and cooking properties. The optimal mixing conditions were determined to be as follows: degree of vacuum, 0.06 MPa; added water, 35.6%; and mixing time, 7.25 min. Furthermore, vacuum mixing produced a more even, coherent, and closed microstructure for the sheeted dough than nonvacuum mixing.  相似文献   
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