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91.
92.
Inter-simple sequence repeat (ISSR) markers were used to evaluate interspecific relationships of Lycoris. Twenty-four samples were included in the study representing a total of 20 among species and varieties. Thirteen primers produced 228 discernible DNA fragments, 205, or 89.91%, of which were polymorphic, indicating a high level of interspecific genetic variation in Lycoris. Our UPGMA cluster analysis recognized four major groups of species, which were consistent with morphological and karyotype observations. The first group included species with telocentric and metacentric chromosomes, while the second consisted of species with a haploid genome of 11 subtelocentric chromosomes. The third group contained species with a mixture of subtelocentric, telocentric and metacentric chromosomes. The last group included the Japanese and Korean species. Lycoris anhuiensis was clustered within accessions of Lycoris longituba, suggesting that it could be recognized as a variety of L. longituba. Our ISSR data also suggested that L. straminea may be a hybrid between Lycoris chinensis and Lycoris radiata var. pumila, and that L. caldwellii, an allotriploid, may be of a hybrid origin of L. chinensis and L. sprengeri. 相似文献
93.
以5年生36个杂种落叶松家系为材料,测定其树高、胸径生长性状,估算变异系数、遗传力和遗传增益,筛选出优良家系。结果表明:各家系的树高、胸径存在较丰富变异,树高变异系数小于胸径,树高、胸径极显著相关(P<0.01),家系间树高、胸径差异均达极显著差异水平(P<0.01)。以10%的入选率,初选出家系1317、1324、1318、和1327为优良家系,树高平均增益为15.98%,胸径平均增益为29.46%。 相似文献
94.
利用杂种一代自由授粉的种子造林,所产生的杂种二代具有明显的增产能力。7年生的落叶松高生长比对照平均增加39.6%,其保存率也普遍高于对照。杂种二代与杂种一代一样具有较强的抗寒能力和适应性。充分利用杂种一代,可节省大量的人力、物力,促进营林生产的发展。 相似文献
95.
笔者以山西杂种榛子引种示范取得的成效为依据,对杂种榛子在山西的发展进行了区域划分,按照自然地理特点可将山西杂种榛子的栽培区域分为高寒冷凉栽培区和气候温和栽培区。认为达维是山西杂种榛子的主栽品种,辽榛3号、晋榛1号是山西杂种榛子的授粉品种。 相似文献
96.
97.
A biologically-consistent stand growth model for loblolly pine in the Piedmont physiographic region, USA 总被引:1,自引:0,他引:1
Oscar García Harold E. BurkhartRalph L. Amateis 《Forest Ecology and Management》2011,262(11):2035-2041
A theory-influenced dynamical stand growth model formulation described well the behavior of thinned and unthinned loblolly pine plantations. A simplification containing few free parameters performed as well as a fully parametrized version. It seems particularly well suited to situations where available data is scarce. The stand model can be interfaced to additional climate, nutrition and carbon cycling modules for studying the effects of a changing environment. 相似文献
98.
针对转基因741杨硬枝扦插难生根的特性,将组织培养及多种扦插繁殖技术有机结合在一起,建立了转基因741杨综合配套育苗体系,提出了适合无性繁殖的“遮阴间歇喷雾扦插”和“移棚不移苗扦插繁殖”育苗方法。转基因741杨组培快繁中,初始启动培养基为MS 6-BA1.0mg/L NAA0.1ms/L,嫩茎增殖培养基为MS 6-BA0.3~1.0mg/L IBA0~0.3mg/L,茎尖生根培养基为1/2MS 0.3IBA 1.5%蔗糖。不同月份嫩枝扦插培养的苗木中,5月份扦插的嫩枝生长较快,但苗木间分化程度较高;8月份扦插的嫩枝生长相对较慢,但苗木的分化程度低,生长整齐。不同月份苗木移栽后,生长节律相同,经过1a生长,不同月份间苗木生长差异不明显,5月份扦插的苗木生长略优于其他月份扦插的苗木。 相似文献
99.
A Review of Fine Root Dynamics in Populus Plantations 总被引:1,自引:0,他引:1
Production of native and hybridized varieties of Populus has received considerable interest in temperate regions as an alternative to agricultural crops and an additional wood source,
while acting as a potential carbon (C) sink to offset emissions of fossil fuel-based greenhouse gases. Research of root system
dynamics in Populus species is expanding, however, our understanding of the nature and role of fine roots (FR) is incomplete. The study objective,
therefore, was to review the literature regarding FR production, mortality and longevity in Populus, and evaluate the magnitude and significance of the FR fraction to C sequestration. FRs, conventionally defined as less than
2 mm in diameter and responsible for water and nutrient uptake, are an essential component of the tree. Populus FRs are relatively short-lived, with reported lifespans ranging from 30 to 300 days, depending on root diameter, tree species
and age, and soil environmental factors. Standing FR biomass fluctuates throughout the growing season. Fine root production
generally peaks in mid-summer, and ranges between 1.0 and 5.0 mg ha−1 yr−1, while FR mortality has less seasonal amplitude. Production and mortality dynamics in Populus are highly plastic in response to soil environmental conditions, and although opposing conclusions have been proposed, research
suggests soil moisture and nitrogen to be most important. Results from the literature indicate annual FR turnover to the soil
C pool may be small (0.2–1.6 mg C ha−1 yr−1), but substantial in maintaining or enhancing C levels in natural and managed stands of Populus. 相似文献
100.
Takaaki Fujimoto Kazuhito Kita Kazuko Uchiyama Makoto Kuromaru Hisashi Akutsu Kazuyuki Oda 《Journal of Forest Research》2006,11(3):157-163
Age trends in variance components and heritability of overall wood density, earlywood and latewood density, and latewood proportion
were investigated in 29-year-old trees of 19 full-sib families of hybrid larch (Larix gmelinii var. japonica × Larix kaempferi) F1. The age–age correlation and optimum selection age for these traits were also estimated and genetic and phenotypic correlations
between wood density and radial growth rate were calculated for each growth ring. Intraring wood density data were obtained
using X-ray densitometry. The coefficient of additive genetic variance was stable over all ages, whereas the coefficient of
environmental variances gradually decreased with increasing age, resulting in increases in heritability estimates with age
for overall density. The latewood proportion had the highest heritability estimates at all ages, ranging from 0.44 to 0.66.
Overall density and its various components at 28 years of age showed strong genetic correlations with their respective traits
at all younger ages. Optimum selection ages for the wood density traits ranged from 8 to 14 years, at which point maximum
gain efficiencies per year were obtained. There were negative correlations between wood density and radial growth rate at
early ages, although these relationships tended to be weaker with increasing age. These results suggest that selection at
a young age is effective for wood density, but particular care must be taken in selecting trees with an improved radial growth
rate because rapid growth will result in a low-density wood product, especially in the early growth period. 相似文献