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931.
以野生天蓝苜蓿种子发育5~7d无菌苗的子叶、下胚轴和种子苗叶片为外植体,对其愈伤组织诱导及其分化的基本培养与外源激素组合和浓度配比进行试验。结果表明:对子叶、下胚轴和叶片愈伤组织诱导最适宜的基础培养基分别是MS、B5和SH;激素的种类及其浓度配比对于愈伤组织的诱导因不同的外植体有很大的差异。其中,子叶、下胚轴以MS+NAA(0.5~1.0 mg/L)+6-BA(0.7mg/L)效果较好,叶片以SH+NAA(0.5~1.0mg/L)+2,4-D(1.5~5 mg/L)+6-BA(0.7mg/L)较好,少量下胚轴在MS+NAA(0.5mg/L)+6-BA(0.7mg/L)和MS+NAA(0.5mg/L)+KT(0.5 mg/L)的培养基中直接分化出胚状体,并成功发育成植株。在培养基Whb5上,子叶、下胚轴和叶片的分化都得到了很好的效果,分化率分别为43%、57%、40%,15~30d后都能再生植株。 相似文献
932.
鳞毛蕨(Dryopteris filix-mas)天山云杉林种群结构分析 总被引:7,自引:5,他引:7
以西天山国家自然保护区内1 hm2原始鳞毛蕨(Dryopteris filix-mas)天山云杉纯林临时标准地调查材料为基础,分析鳞毛蕨天山云杉林胸径、树高和年龄结构、种群存活曲线以及基本测树因子之间的相互关系.结果表明:①鳞毛蕨天山云杉纯林种群结构稳定,无论是胸径、树高抑或年龄,均呈现出明显的倒"J"型,属于典型的异龄林林分结构,林木更新良好,在其自维持过程中不断有大量小径木更新补充;②林木株数随胸径、树高和年龄的增大,呈负指数函数或负幂函数递减;③树木胸径和树高随年龄的增大,按理查兹生长曲线递增;④胸径与树高的关系为非线性关系.此外,种群存活曲线总体趋势呈现"凹"型,表明该种群是一个连续更新的种群,在林分生长发育过程主要受到小尺度林冠干扰的影响. 相似文献
933.
地下微生境位置的确定对于干旱区植被生态系统的恢复具有重要意义,但目前尚没有准确、简单可行的确定方法.应用额济纳盆地的野外调查与室内实验数据,分析了3类植物群落结构(草本 灌木组合、灌木 乔木组合及草本 灌木 乔木组合)中的土壤过氧化氢酶活性曲线.结果发现:过氧化氢酶活性曲线的各峰值区与植物群落中各生活型植物的根群位置对应,而已有研究指出植物的根群位置正与植物的地下微生境位置对应.因此,可以通过分析过氧化氢酶活性曲线来确定植物地下微生境的空间位置. 相似文献
934.
B. Wang C. L. Brubaker W. Tate M. J. Woods B. A. Matheson J. J. Burdon 《Plant pathology》2006,55(6):746-755
Genetic variation among 348 isolates of Fusarium oxysporum f.sp. vasinfectum (Fov) collected from diseased cotton plants in 31 fields in six cotton-growing regions in New South Wales and Queensland in 2002 and 2004 was analysed using amplified fragment length polymorphisms (AFLPs). Twenty-eight haplotypes were identified based on 146 polymorphic bands generated with four Eco RI and Mse I and four Hind III and Mse I primer combinations. The haplotypes separated into two distinct groups (37% similarity), with 21 in group I and seven in group II. The two unique vegetative compatibility groups of Fov known to occur in Australia (VCG 01111 and VCG 01112) were correlated to the two AFLP groups, with both VCG 01111 reference isolates being included in group I and both VCG 01112 reference isolates in group II. Group I was widespread, occurring in all regions sampled and all but one of the fields, while group II was limited to three fields in the Boggabilla region. Group I was further divided into two subgroups. The two haplotypes in subgroup I-B (I-20 and I-21) may represent the emergence of a new form of Fov based on their marked genetic discrimination from the subgroup I-A haplotypes. No spatial population differentiation was discernible at the national level, as only 3·9% of total genetic variation was attributed to differences among regions ( P = 0·4868). When each region was analysed separately, clear differentiation was found in the Boggabilla region, with 86·3% of total genetic variation resulting from differences among fields ( P < 0·0001). 相似文献
935.
Through a detailed case study of a two‐species (Lolium rigidum and Avena sterilis) weed community at contrasting scales, this paper examined factors that affect weed distribution across space and time in a commercial wheat field in north‐east Spain. A. sterilis showed relatively stable spatial distribution and spatial structure of its population over time at large scale, with well‐defined patches, although weed density rose quickly. L. rigidum showed poorly defined patches that were not stable across time. Interaction between species could explain to some degree the spatial distribution at large scale: a negative relationship was detected between the spatial structures of both weed populations. At fine scale, both species showed a clear interaction effect from primary dispersal (more important in A. sterilis) and secondary dispersal from combine harvesting (more important in L. rigidum). 相似文献
936.
纤维素复合酶对羔羊消化道组织结构的影响 总被引:1,自引:0,他引:1
为了探明纤维素复合酶提高羔羊饲料消化率的消化道组织学基础,选择刚出生且体重相近的波尔山羊公羔30只(20日龄开始自由采食优质苜蓿干草, 80日龄断奶)分为对照组和试验组(添加0.2%酶制剂),分别在2、3和4月龄每组各选体重相近的3只羔羊屠宰.结果表明,瘤胃乳头长度、宽度和单位面积瘤胃乳头表面积随月龄增加而增加,而单位面积乳头数随着月龄的增加而减少(P < 0.01).酶制剂提高3、4月龄羔羊瘤胃乳头长度(P < 0.01)、宽度(P > 0.05)和单位面积瘤胃乳头表面积(P < 0.01),减少单位面积乳头数(P < 0.01).显著提高3月龄十二指肠肠绒毛的长度(P < 0.05).在3、4月龄,酶制剂有增加小肠隐窝深度和黏膜厚度的趋势,但未达到显著水平(P > 0.05). 相似文献
937.
938.
Although the spatial genetic differentiation that occurs in animal populations has been extensively studied, information on temporal variations in genetic structure and diversity is still lacking, especially for animals with oscillating populations. In the present study, we used the mtDNA D‐loop sequence to assess the temporal genetic variation in samples from six successive years for the greater long‐tailed hamster, Tscherskia triton. Sampling was carried out between 1998 and 2003 in cropland on the North China Plain, China. A total of 108 individuals were analyzed. The temporal samples showed a high level of genetic diversity. Substantial genetic changes in haplotype frequencies over time were detected for the hamster population. Random genetic drift and migration are likely to be the major factors responsible for the observed temporal pattern. The genetic diversity of the hamster population was higher in years with higher population density, and lower in years with lower population density. The result supports our hypothesis that genetic diversity decreases when population density declines in animals whose population oscillates greatly between years. The combined effects of inbreeding and genetic drift caused by reproduction, dispersal and population size might play important roles in the observed changes in genetic structure and diversity between years. 相似文献
939.
940.