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41.
归纳了近几十年来对此类暴雨的研究成果,总结了其气候特征,主要从中纬系统的相互作用、地形作用、重力惯性波、中尺度系统综述了其形成的机理。  相似文献   
42.
In the period 1994–1996 a post-harvest survey was conducted in wheat, barley and oats to assess the occurrence and geographic distribution of Fusarium species in Norwegian cereals. The number of samples investigated was adjusted proportionally to the production of each cereal species within the regions. A total of 695 grain samples were analysed. The amount of Fusarium infection varied with cereal species and region of origin. The most frequently isolated Fusarium spp. from all samples were F. avenaceum, F. poae, F. tricinctum and F. culmorum. Other important toxigenic Fusarium spp. were F. graminearum, “powdery F. poae”, F. equiseti and F. sporotrichioides. A north-south gradient was valid for F. tricinctum, F. poae and in 1994 for “powdery F. poae”. In 1994 “powdery F. poae” was the most abundant potential producer of HT-2 and T-2 toxins in Norwegian cereals. Distribution of F. graminearum and F. culmorum demonstrated in this study, corresponded to previously reported DON-distribution, although DON seems to be produced by different species in different regions. Distribution of the isolated Fusarium species and comparison between cereals and locations are discussed.  相似文献   
43.
氮、磷、钾配施对草原3号苜蓿干草产量的影响   总被引:1,自引:0,他引:1  
采用“3414”试验设计对草原3号苜蓿进行大田施肥,通过对苜蓿干草产量进行多元回归分析和模拟寻优分析来探索氮、磷、钾肥的肥料效应。结果表明,施肥在不同程度上增加了苜蓿干草产量,增产幅度在7.20%~26.85%之间,增产最高的施肥处理是P2K1N1;在单因子施肥效应中,苜蓿干草产量随着磷肥施入量增加而增加,随着钾肥和氮肥施入量增加而先增加后降低。在两因子互作效应中,氮磷、磷钾互作对苜蓿干草产量具有一定的促进作用,氮钾互作对苜蓿干草产量具有一定抑制作用。通过模拟寻优分析得到最优施肥配比为P2O5 180.22kg/hm^2、K2O 52.82kg/hm^2、N 41.84kg/hm^2,产量达11257.09kg/hm^2。磷、钾、氮以及饲草产量的最优配比区间分别为178.2~182.33kg/hm^2、51.38~54.38kg/hm^2、40.8~42.9kg/hm^2、11247.36~11266.82kg/hm^2。  相似文献   
44.
郭殿荣  吴玉林 《蚕业科学》1994,20(4):225-230
室内药敏试验0.1%—0.5%保蚕宁2号对柞蚕链球菌有抑制作用,四龄盛食期添食0.13%保蚕宁2号对柞蚕再感染空胴病有防治作用,旦效果显著。小区试验经添食药物的空胴病发病率下降69.5%,死笼茧率平均下降38.25%,结茧率平均提高50.25%。农村多点试验治愈率达63%,发病率下降67.3%,结茧率提高52.11%。保蚕宁2号药源充足,价格适宜,可在柞蚕生产区普遍推广应用。  相似文献   
45.
The study assessed the success of “Cocoa na Chocolate” musical intervention for agricultural mobilization in Oyo State, Nigeria. Responses from 160 randomly selected students on awareness, exposure, retention, perception, and constraints to utilizing its message using structured questionnaires were analyzed. Most respondents (88.8%) had contact with the album, many (55.6%) were aware of its agricultural content, heard it six times, and most (76.1%) retained the contents. More (54.9%) had an unfavorable perception of its mobilization potential, and were constrained to utilize its message by credit facilities (M = 1.0938). Workable agricultural credit schemes are needed to complement future mobilization efforts.  相似文献   
46.
Whole-genome sequencing of “Candidatus Liberibacter asiaticus” (Las) indicated some polymorphic gene regions enabling the molecular characterization of this bacterium. Although the population diversity of Las in China has been previously studied, no reports have used a combination of a prophage region and short tandem repeat (STR) loci for phylogenetic relationship characterization. In this study, we investigated the genetic diversity and structure of 667 Las strains from nine provinces in southern China using multiple genetic loci including three type-specific prophage loci, two STR loci, and a miniature inverted-repeat transposable element (MITE) region. The results indicated that the genetic diversity varied according to the gene loci used. The prophage regions, including the MITEs, revealed significant genetic differences of Las populations in Yunnan and Guizhou from other provinces, while the STR loci only indicated a difference of Las population in Guizhou from those of other provinces. In particular, the Las population shown to be diverse in Jiangxi at the CLIBASIA_01215_STR locus was not diverse when measured using the other loci. Considering all loci, the Las populations from Yunnan and Guizhou were different, those from Guangdong and Guangxi were complex, while the Las population in Jiangxi was comparatively simple. Las populations from five neighbouring provinces, including Guangdong, Guangxi, Hunan, Fujian, and Jiangxi were grouped in a big cluster. The Las population structure changed with age according to the prophage type. This study evaluated the method used for studying the molecular diversity of Las populations and provided more detailed information on the geographical origin and epidemic trend of Chinese Las populations.  相似文献   
47.
Seed shattering is a significant problem with buckwheat, especially at harvesting time. Several reports have shown that a green-flower mutant of buckwheat, such as W/SK86GF, has a strong pedicel. Although a strong pedicel may provide some resistance to shattering in the field, no study has thoroughly examined this issue. In this paper, we demonstrate that a W/SK86GF has shattering resistance by comparing the degrees of shattering of W/SK86GF and Kitawasesoba (leading variety of Hokkaido with non-green-flower traits) through a test for four years, including a typhoon hit year in the field. In a non-typhoon year, the shattering seed ratio (shattering seed weight/(yield + shattering seed weight) × 100) of W/SK86GF at maturing time +15 days (+15D) was lower than that of Kitawasesoba. In a typhoon hit year, the shattering seed ratios of Kitawasesoba at maturing time and +15D were surprisingly high, 14.4 and 21.1%, respectively. On the other hand, those of W/SK86GF were only 3.08% and 2.57%, respectively; indicating W/SK86GF is promising as a shattering resistant line even in a typhoon hit year. From these results, shattering resistance of W/SK86GF can be evaluated after maturing time such as +15D and pedicel strength would confer W/SK86GF a shattering resistant trait.  相似文献   
48.
为了筛选出优良家系及单株,为桉树良种改良提供优质的遗传材料,对27月生30个桉树杂种家系试验林的生长和抗风能力进行分析和遗传评估.结果表明:试验林的树高(H)、胸径(D)、材积(V)、抗风指数(WR)在家系水平上、家系×重复交互作用水平上均存在极显著的差异(P<0.01),在家系水平上4个性状均受到较高程度的遗传控制,单株水平上H、D、V3个性状受到较高强度的遗传控制,而WR受到较弱程度的遗传控制.遗传相关分析表明H、D、V、WR4个性状两两之间都呈极显著正相关(P<0.01),其中,在生长性状中,D与V之间的相关关系最为密切;在抗风能力方面,WR与D之间的相关关系最为密切.通过构建性状选择指数方程,按照选择标准选出8个优良家系,39个优良单株,入选率分别为26.67%、5.65%.其中优良家系的遗传增益在H、D、V和WR上分别达到了8.24%、9.99%、25.24%和3.76%,优良单株的遗传增益在H、D、V和WR上分别为22.55%、13.45%、105.49%和1.90%.  相似文献   
49.
知识服务是高校图书馆的核心服务,概述了知识创新及知识创新服务的内涵,探讨了高校图书馆知识创新服务现状,提出互联网+高校知识创新服务管理策略,包括向融合图书馆转型、打造智慧馆员、移动交互式大平台建设、构建知识创新服务体系、图书馆空间的再造等。  相似文献   
50.
[目的]为正确认识台风对桉树人工林蒸腾耗水的影响。[方法]采用热扩散茎流计对尾巨桉树干液流在台风前后进行连续监测,分析其对台风天气的响应,并同步测定林分气象条件,分析台风过程中树干液流与气象因子之间的相关性。[结果]表明:台风当天,树干液流密度与台风登陆前后(单峰)不同,呈不规律多峰型曲线,树干日均液流密度(2.89 mL·h~(-1)·cm~(-2))较台风前减少53%,夜间液流波动较大;日间最大峰值(7.76 mL·h~(-1)·cm~(-2))出现在下午,峰值较台风前降低55%,树干液流日通量极显著小于台风登陆前后;台风登陆前树干液流密度峰值(17.4 mL·h~(-1)·cm~(-2))及平均液流密度(6.15 mL·h~(-1)·cm~(-2))分别是台风登陆过后的1.24倍和1.14倍,台风后树干液流日通量较台风前均有所下降;台风当天,影响液流的主要气象因子为风速、大气温度、空气湿度、水汽压亏缺和降雨量,液流与风速的相关系数较台风前增大52%,与降雨量的相关系数是台风前的2.6倍,与其他因子的相关系数较台风前均下降了50%左右,而台风登陆前后之间的主要影响因子差异不大。[结论]台风当天的日均液流密度、白天的平均液流密度和日通量均极显著小于台风前后,而夜间液流显著大于台风前后;台风前后的日均液流密度差异不显著,夜间液流台风前显著大于台风后;台风过程中风速成为影响液流的关键因子,与太阳辐射相关性不显著,其他影响因子与台风前后相同,但相关系数除风速和降雨量外均显著下降。  相似文献   
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