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991.
在已有的氯离子扩散理论和孔隙分形理论的基础上,提出小孔的孔轴线分形维数表征氯离子扩散的曲折度、大孔的孔表面分形维数修正孔隙率,并推导得到基于孔隙分形修正的氯离子扩散系数模型。通过分析龄期为14 d和28 d不同配比混凝土的基于孔隙分形的氯离子扩散系数模型的计算结果和快速氯离子扩散试验(ASTM C1202)电通量,发现两者之间有良好的线性关系。采用基于孔隙分形修正的氯离子扩散系数代入Fick第二定律的解析解,对试验后各组混凝土中不同扩散深度的氯离子浓度进行拟合,计算结果与实测值吻合情况较好。 相似文献
992.
993.
《Journal of Cereal Science》2014,59(3):472-478
To study the role of abscisic acid (ABA) and gibberellin (GA) sensitivity in regulating pre-maturity α-amylase (PMA) in wheat grains, plants were grown in a glasshouse under cold-shock and ambient conditions. α-amylase activity in response to applied ABA and GA was measured in detached-grains with the embryo removed (in vitro) and in intact-grains attached to the plant (in situ). The in vitro experiment was conducted using Spark (low PMA-susceptible genotype) and Rialto (highly PMA-susceptible genotype), with the aim of defining the time point for GA-sensitivity. The results showed an increase in GA-sensitivity at about 640 degree days after anthesis (DAA) in Rialto. There was no evidence for a change in ABA-sensitivity in either variety. The in situ experiments were conducted using genotypes from a Spark × Rialto doubled haploid population segregating for the Rht-D1a (tall) or Rht-D1b allele and for the presence or absence of 1BS/1RS. For Rht-D1a (tall) or Rht-D1b genotypes with or without 1BS/1RS, the cold-shock significantly increased GA-sensitivity, whereas there was no significant change in ABA-sensitivity. These results show PMA is related to an increase in GA-sensitivity that occurs in the aleurone at around 640 degree DAA, and can be enhanced by environmental factors (e.g. cold-shock). 相似文献
994.
The University of Minnesota Gaura breeding program is developing USDA Z3-4 winter-hardy genotypes via interspecific hybridization of G. lindheimeri (Z5-6) and G. coccinea (Z2-4). Prior to commencing interspecific hybridization, the reproductive barriers operating in both parental species need to be characterized. The objective of this research was to determine the type and stability of reproductive barriers operating in G. lindheimeri by statistical comparisons between pollen tube growth and seed set in a full-sib diallel. Slowed or aborted pollen tube growth in the style indicated the presence of a gametophytic self incompatibility (SI) system. A statistical method, female (FCC) and male (MCC) coefficients of crossability, was used to verify that a stable SI system was operating and that other reproductive barriers were present. Several genotypes also expressed stage-specific inbreeding depression and incongruity. The simple linear regression equation for FCC/MCC, using pollen tube growth, was Y = 0.0124 + 0.974X, which was much closer to the expected Y = 0.0 + 1.0X (indicating a stable SI system) than the equation for seed set, Y = 0.012 + 0.910X. Using pollen tube length, both general combining ability (GCA) and specific combining ability (SCA) values were highly significant for G. lindheimeri (P ≤ 0.001). Histograms were used to delineate cut-offs to identify intra-incompatible/inter-compatible classes and S allele groups. Four possible classes were identified, but further research is needed to verify S allele genotypes.Scientific Research Paper No. 031210120 of the Department of Horticultural Science. This research was supported by a grant from the Perennial Plant Association and, in part, by the Minnesota Agricultural Experiment Station 相似文献
995.
Saxena MK Singh VP Kumar AA Chaudhuri P Singh VP Shivachandra SB Biswas A Sharma B 《Veterinary research communications》2006,30(8):851-861
Repetitive extragenic palindromic sequence-based PCR (REP-PCR) was used to characterize 67 field isolates of Pasteurella multocida originating from different animal species and geographical regions of India. REP-PCR was found to be rapid and reproducible
(three repeats were done). These isolates yielded different 23 profiles which were clustered into eight groups. The discrimination
index was moderate (D value 0.83). Somatic and antigenic typing of the isolates did not reveal any correlation with REP-PCR profiles. There was
no host-specific, type-specific, region-specific or pathenogenicity-specific pattern. The REP profiles of isolates obtained
from wild animals were similar to those obtained from domestic animals. Two common bands were present in all the isolates
irrespective of somatic or antigenic types. The results were not comparable with earlier findings, which had shown high discrimination
index and correlation with disease presentation.
Saxena, M.K., Singh, V.P., Kumar, A.A., Chaudhuri, P., Singh, V.P., Shivachandra, S.B., Biswas, A. and Sharma, B., 2006. REP–PCR
analysis of Pasteurella multocida isolates from wild and domestic animals in India. Veterinary Research Communications, 30(8), 851–861 相似文献
996.
997.
采用最近邻体列联表法和计算主要树种混交度的方法,研究亮叶水青冈天然次生林不同树种的种间分离特征。结果表明:1)亮叶水青冈空间分布格局为聚集型,该群落中随机毗邻种对的数量占优势(比例达69.89%),正分离种对较少(比例为29.88%),负分离种对极少(仅为0.23%)。星座图清晰显示种间分离在不同种之间存在一定的差异。2)随着亮叶水青冈在群落中的重要值增大,亮叶水青冈与其他树种发生正分离的种对也增加;随着亮叶水青冈径阶增大,与其他树种的分离关系逐渐接近自然状态,即以随机毗邻为主,正分离次之,负分离不存在。3)群落的平均混交度较高,取值集中在0.5~0.75,说明整体上树种之间的隔离程度较大;亮叶水青冈的混交度值为0.34,处于弱度与中度混交之间,趋向于聚集分布;茅栗、四照花等主要伴生树种的混交度在0.75左右,可以视为强度混交。种间分离类型比例和主要树种混交度的取值分析均说明该亮叶水青冈群落的稳定性较强。 相似文献
998.
以27个标准切花菊品种为试材,对标准切花菊花径及11个重要数量性状进行了遗传相关、相关遗传力及通径分析等。结果表明:12个性状的遗传力较高,达到了70%以上;花径大小与最外轮舌瓣长、次外轮舌瓣长存在极显著遗传相关关系,与次外轮舌瓣宽存在显著遗传相关关系;最外轮舌瓣长和次外轮舌瓣长同花径的相关遗传力与花径的遗传力接近,相关选择效率接近对花径的直接选择效率;选择舌瓣花长、舌瓣花多、管瓣花少、植株高度较高的品种是选育优良切花菊的有效途径。 相似文献
999.
Irwin R. Donis-González Daniel E. GuyerAnthony Pease Dennis W. Fulbright 《Postharvest Biology and Technology》2012,64(1):74-82
Little is known about Chestnut (Castanea spp.) in vivo cultivar characterization and morphology, the effect of mechanical harvesting, peelability, postharvest mold, physiological kernel decay, and quality. Thus, there is a need to develop a nondestructive technique able to assess fresh chestnut internal components, especially disorders. In this study, a medical grade computed tomography (CT) was used to obtain transversal two-dimensional (2D) images from decayed and healthy fresh chestnuts, from the hybrid cultivar ‘Colossal’ and ‘Chinese seedlings’. Attenuation coefficients, referred to as Hounsfield-units (HU) or CT numbers, were acquired from different 2D CT image regions including air, and several chestnut components containing decayed tissue, healthy tissue, various imperfections such as pellicle invagination into healthy kernel, and void spaces. Results offer an in vivo accurate insight of fresh intact chestnuts, and suggest that CT technology is appropriate for inline sorting. HU measurements can be used as a nondestructive predictor of fresh chestnut internal components with a 90.6% overall accuracy rate. 相似文献
1000.
为了测定SPF级Balb/c、KM、NIH小鼠血常规、主要脏器质量、主要脏器系数并进行比较,采用Coulter-JT全自动血常规检测仪检测小鼠血常规;精确称量小鼠主要脏器质量,计算其脏器系数。结果表明,SPF级KM小鼠与Balb/c小鼠相比,血常规指标中有14项指标有显著性差异(P<0.01或P<0.05,下同),主要脏器质量指标中有8项指标有显著性差异,主要脏器系数指标中有5项指标有显著性差异;SPF级NIH小鼠与Balb/c小鼠相比,血常规中有15项指标有显著性差异,主要脏器质量指标中有10项指标有显著性差异,主要脏器系数指标中有9项指标有显著性差异。说明不同品系小鼠某些血常规值、主要脏器质量、主要脏器系数方面有较大不同。 相似文献