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81.
中国臭蚁属分类研究:膜翅目 蚁科 臭蚁亚科   总被引:2,自引:1,他引:2  
记述中国臭蚁属昆虫5种,其中描述1新种。研究了在中国记载的种和变种,提出4个新异名,提供4种的测量、描述、插图和分布,编制了工蚁分种检索表。模式标本保存于西南林学院森保系昆虫标本室,云南昆明。  相似文献   
82.
粗糙集神经网络在昆虫总科阶元分类学上的应用   总被引:2,自引:0,他引:2  
为研究粗糙集和神经网络相结合方法的实践性,以及昆虫的数学形态特征在总科阶元上作为分类特征的可行性、可靠性和重要性。从总科角度对鳞翅目(Lepidoptera)和鞘翅目(Coleoptera)5个总科23种虫体图像中提取的昆虫面积、周长等11项数学形态特征进行粗糙集神经网络分析。结果表明:在总科阶元上,11项特征的可靠性大小为,面积、亮斑数>周长、横轴长、形状参数、圆形性、似圆度、偏心率>纵轴长、叶状性、球状性,与赵汗青等的统计分析结果中属性特征的重要性大多数一致;神经网络模式识别结果与传统分类结果完全一致。应用粗糙集理论进行昆虫数学形态特征分类结果准确;在昆虫总科阶元分类上粗糙集神经网络较统计学方法具有优势。  相似文献   
83.
Soil systematics and classification systems Part I: Fundamentals Soil‐ordering systems are primarily based and developed on one of two underlying principles: They are either categorized according to soil‐forming processes, or the formation of categories develops by chosen parameters. This perspective has already been established in the literature, though it is often confusing as many terms are defined and applied differently. In this contribution, the various definitions of systematics, classification, taxonomy, and identification will be clearly differentiated and summarized. The core of our work is to clearly define and contrast three terms: systematics, classification, and identification. Systematics is the fundamental scientific and deductive ordering of objects into systematic units. The purpose of this approach is to organize the entire spectrum of knowledge within a discipline into a transparent and manageable form. Classification, in direct contrast to systematics, is goal‐oriented and an inductive ordering of objects. Thus, the ordering scheme consists of classes which are clearly parameterized. Identification is the ordering of new objects into an already existing systematics or classification system. Close attention is paid to both the differences and the similarities between a systematics and a classification system, especially pertaining to their practical applications. The identification requires that the category‐forming characteristics can be measured (e.g., for soil systematics, these are the soil‐forming processes and factors). Currently, it is unfortunately not feasible to objectively quantify most soil‐forming processes. Thus, most attempts at categorizing soils by systematics are hypothetical and highly subjective in nature. The resulting identification derived from the soil systematics approach is open to questions and contestable, since a graded measuring system does not yet exist to verify these determinations. In contrast, a soil‐classification system does allow an objective soil‐profile identification, although such systems are conceived pragmatically and designed for a practical purpose (e.g., not scientifically based on process intensities). Unfortunately, such a classification system cannot be applied as a universal scientific categorization system due to this method of conception. Both categorization approaches are required in soil science in order to satisfy both the practical and the scientific aspects of the field. However, substantial research must be done to complete and verify systematics. The only viable short‐term solution is through the development of a graded classification system where the categories of the system are directly derived from the current systematics approach. In the long run both the exact investigation and the detailed modeling of the soil‐forming processes are inevitable.  相似文献   
84.
Summary Contrary to views that cassava (Manihot esculenta) is only known in cultivation an argument is made that wild accessions of the species grow over much of the American neotropics, in Brazil, Bolivia, Peru, Venezuela, Guyana, and Surinam. Three subspecies are recognized. M. esculenta subsp. esculenta is the domesticate and includes all cultivars known in cultivation. The wild M. esculenta subsp. peruviana occurs in eastern Peru and western Brazil. The wild M. esculenta subsp. flabellifolia shows a wider distribution and ranges from the central Brazilian state of Goiás northward to Venezuelan Amazonia. The large area of distribution of the two wild subspecies makes it difficult to assign a place of initial domestication.  相似文献   
85.
88 herbarium specimens of the genus Lolium were scored for 22 characters, comprising 7 vegetative, 8 inflorescence and 7 seed characters. The aim was to review the species relationship and to produce a lateral key to the genus. The data were analysed using principal components analysis, discriminant function analysis and cluster analysis. All analyses separated L. perenne, L. multiflorum and L. temulentum from each other. The 2 varieties of L. rigidum showed varying degrees of separation from each other and from L. multiflorum. Their distinction as a species and as 2 varieties is discussed. L. perenne and L. rigidum were shown to contain the greatest similarity between species and L. temulentum was found to be the most distinct. A lateral key is proposed that separates the species on the basis of 11 morphological characters that are easily scored in the field.  相似文献   
86.
Nuclear RFLPs were used to study the genetic relationships of 2 Portuguese coles, tronchuda cabbage and Galega kale, and 13 otherBrassica oleracea cultivars and 4 nine-chromosome wild brassicas. Cluster and principal coordinates analysis were conducted using RFLP data from 60 probe-enzyme combinations, detecting 277 polymorphic restriction fragments. The results showed that the accessions clustered in five groups: one with all theB. oleracea cultivars except kailan, and the four others isolated with kailan, wildB. oleracea, B. insularis andB. cretica, andB. montana, respectively. Kailan was separated from the other accessions ofB. oleracea cultivars and genetically close to the wildB. oleracea, that was clearly separated from the other nine-chromosome wild brassicas. In theB. oleracea cultivars 3 groupings were clearly individualized: i) including broccolis and cauliflower; ii) with a misture of kales and cabbages originally from Central-North Europe; iii) formed by Portuguese coles. These preliminary results suggest the existence of three major regions of domestication of B. oleracea in Europe: Italy, Central-North Europe and Portugal. Kailan or chinese kale seems to have evolved separately from the otherB. oleracea cultivars in Eastern Asia.  相似文献   
87.
Amplified Fragment Length Polymorphisms (AFLPs) were employed within the taxonomically difficult Solanum nigrum L. complex in order to characterize the genetic diversity present in a collection of the Gatersleben Genebank, to classify taxonomically unknown material, and to correlate the clustering of the examined accessions with their geographic origin. The results from AFLP analyses using two primer combinations on 44 entries from five species led to the detection of four major clusters, simultaneously uncovering significant differences in the levels of genetic diversity within or between species. S. americanumexhibited the highest infraspecific variation despite close geographic origins, simultaneously being placed in a clearly separated cluster in comparison to the other examined species of the complex. In addition, these other species showed even less interspecific variation than was found at the infraspecific level in S. americanum. In terms of taxonomy, the application of AFLPs helped in the classification of 13 black nightshade accessions formerly only listed as Solanum sp. This also was confirmed by morphological determination. Furthermore, one accession formerly classified as S. physalifolium var. nitidibaccatum i) clustered with AFLPs and ii) was identified morphologically as S. villosum. Contradictory classifications remain for two further entries from the same species, found within the S. nigrum cluster after AFLP analyses, while belonging to S. physalifolium var. nitidibaccatum according to herbarium specimen. Finally, as indicated by the information on provenance in geographically separated subclusters in S. americanum and partially in S. villosum, clues on the currently unknown origin of accessions from the genebank seem feasible by AFLP data.  相似文献   
88.
对甘蔗育种有重要利用价值的除Saccharum属外,还有一些与之关系密切的近缘植物.它们构成了“Saccharum复合群”,包括:Miscanthus属、Erianthus属的Ripidium部分、Sclerstachya属、Narenga属和Saccharum属。本文评述了这些植物的分类、分布、特征特性及对甘蔗育种的意义。  相似文献   
89.
杨树栅锈菌Melampsora spp的数量分类研究   总被引:1,自引:0,他引:1  
栅锈菌种Melampsora spp.的分类过去主要根据其寄主、转主寄主范围及冬孢子形态特征;但用这个原则对杨树上栅锈菌分类是很困难的。因为:1.冬孢子的相似性,大部分杨树栅锈菌的冬孢子在形态上区别不显著;2.多寄主性;3.交叉发生性;一种杨树甚至同一棵树上能同时有两种栅锈菌存在;4.缺转主寄主性;即有些杨树栅锈菌不经转主寄主而完成生活史;5.强制接种可以使非寄主植物发病。由于分类中遇到的上述困难,使杨树栅锈菌的分类转向了夏孢子阶段的性状。Kraa-  相似文献   
90.
曾义雄1980年发表了巨须螨科(Cunaxidae Thor,1902)的一个新属Lapicunaxa,但属以上的分类地位一直未确定。根据J.Den Heyer(1980)的新分类系统和作者的研究认为,该属似应上升为亚科,定名为叠板巨须螨亚科La-picunaxinae。  相似文献   
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