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131.
中国热带地区不同作物长期轮作对土壤线虫群落结构及多样性的影响 总被引:1,自引:0,他引:1
A field experiment was carried out from 2003 to 2013 in the Wanzhong Farm of the Hainan Island, China, to determine the effects of two long-term banana rotations on the abundance and trophic groups of soil nematode communities in the island. The experiment was set out as a randomized complete block design with three replications of three treatments: banana-pineapple rotation(AB), banana-papaya rotation(BB) and banana monoculture(CK) in a conventional tillage system. Soil samples were taken at depths of 0–10, 10–20 and 20–30 cm, and nematodes were extracted by a modified cotton-wool filter method and identified to the genus level. Nematode ecological indices of Shannon-Weaver diversity(H′), dominance index(λ), maturity index(MI), plant parasite index(PPI), structure index(SI), enrichment index(EI), and channel index(CI) were calculated. A total of 28 nematode genera with relative abundance over 0.1% were identified, among which Tylenchus and Paratylenchus in the AB, Thonus in the BB, Tylenchus and Helicotylenchus in the CK were the dominant genera. The rotation soils favored bacterivores, fungivores and omnivores-predators with high colonizer-persister(c-p) values. Soil food web in the rotation systems was highly structured, mature and enriched as indicated by SI, MI and EI values, respectively. Higher abundance of bacterivores and lower values of CI suggested that the soil food web was dominated by a bacterial decomposition pathway in rotation soils. Nematode diversity was much higher after a decade of rotation.Soil depth had significant effects on the abundance of soil nematodes, but only on two nematode ecological indices(λ and MI). 相似文献
132.
SSR标记在玉米遗传多态性及杂种优势群划分中的应用 总被引:1,自引:2,他引:1
描述了SSR分子标记的基本概念,简述了SSR标记在玉米遗传多态性分析、杂种优势群划分以及玉米轮回选择群体的遗传多样性方面的应用,同时展望了其应用前景。 相似文献
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[目的]为探索商品有机肥在新烟区对烤烟的影响,筛选出适合红塔集团遮放烟叶基地单元使用的商品有机肥。[方法]对4种商品有机肥进行大面积对比试验示范,调查各处理烤烟主要大田生育期、农艺性状、经济性状,并且对初烤烟叶进行外观质量和内在化学成分检测分析。[结果]施用有机肥能够促进烟叶落黄成熟,缩短KRK26品种大田生育期,且能提高烟叶产值,提高初烤烟叶外观质量光泽度和烟叶产值量,初烤烟叶化学成分趋于协调。[结论]在几种商品有机肥中,李杨牌有机肥的总体表现较好,可以在基地单元作进一步试验示范。 相似文献
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Chlamydial complement fixing antibodies were followed in 5 small Finnish dairy herds. All 53 animals in the herds were bled. In herds A, B, C and D the blood samples were collected in May and in the following autumn after the pasturing period and in herd E over a period of 2 years at about 1 ½-month intervals. The frequencies of positive reactions among the adults and the calves younger than 1 year did not differ significantly from each other, but there were considerable seasonal variations in the frequencies. The highest frequency was found during springtime and early summer and the lowest in autumn. 相似文献
138.
CHENG Zengqing FAN Gencheng DOU Xiaolong LIU Hongxiang SHEN Maoxin XU Quangang YANG Hanchun 《畜牧兽医学报》1956,51(10):2463-2471
The aim of this study was to identify pathogens, which caused pericardial effusion, hepatomegaly and bleeding at a chicken farm in Henan province, and furthermore to analyze effectiveness of immunogenic proteins of the pathogen. This study employed virus isolation, serological assays, PCR and sequencing analysis, animal experimentation, E. coli expression and protein purification, immunogenicity and challenge test and other methods. The results showed that virus was isolated in 7-day-old SPF chicken embryonated eggs, inoculated via the yolk sac route by two blind passages. Viral confirmation was carried out using PCR techniques, and showed a 900-bp-long fragment which shared a 100% homology with the Hexon gene of the serotype C4 strain. Serum neutralization results indicated that this isolate avian adenovirus was the group I type 4 avian adenovirus, named HN-ZK strain. The virus could induce CPE on primary hepatocytes of chicken embryo, and its titer was 107.5 TCID50·0.1 mL-1. Animal experimentation illustrated that the isolated virus caused 100% (10/10) typical symptoms and pathogenicity in 35-day-old SPF chickens. Furthermore, the DNA of the isolate virus was used as a template to express Fiber-2 fragment, with a molecular weight of 33 kDa by using the E. coli expression system, and the protein was concentrated and purified to 300 mg·mL-1 after centrifugation and purification. SPF chickens were immunized with different doses of the purified Fiber-2 protein, and showed that a dose of 20 μg per chick was completely resistant to challenge of the virulent virus, suggesting the purified Fiber-2 protein has better immunogenicity. This study can provide data for diagnosing the hydropericardium hepatitis syndrome, and developing a genetic engineering subunit vaccine. 相似文献
139.
油松毛虫卵(块)和蛹种群简单随机抽样最适样方大小的确定方法 总被引:1,自引:0,他引:1
在种群空间格局的研究的基础上,采用7种方法对同松毛虫卵(块)和蛹种群简单随机抽样技术中最适样方大小的确定问题进行了研究,结果表明,无论是卵(块)抑或蛹种群,都是在u=1时抽样误差最低,即以单株油松为样方时最为适宜,此外,文中还列出了考虑抽样花费时确定最适样方式大小的各种方法,并讨论了有关问题。 相似文献
140.
Magana JG Tewolde A Anderson S Segura JC 《Tropical animal health and production》2006,38(7-8):583-591
The objective was to evaluate the effect of cow genetic group, nutritional level and their interaction on some economically
important traits of dual-purpose herds managed under field conditions. Nine herds were monitored during a production cycle
in Yucatan, Mexico. Herds were grouped into four nutritional levels (NL) based on the metabolizable energy (ME) apparently
available on pasture, nutritional management, and milk production. Cows were classified into three genetic groups (GG): low
(≤25%), middle (25–75%) and high (≥75%) graded for Bos taurus inheritance. Total milk sold (TMS), days in milk (DIM), TMS adjusted to DIM within each NL (TMSA), body condition score (BCS)
at calving, changes of BCS during lactation (CBCS), calf weaning weight (WW), age at weaning (AW), kg of calf weaned per cow
(KWC) and calf mortality were studied. The statistical model included the fixed effects of NL, GG, month of calving (MC),
parity number (PN) and BCS at calving and GG × NL interaction. The effects of NL, GG, MC, PN and GG × NL were significant
(p < 0.05) for TMS, KWC. As expected, TMS increased with NL from 562.4 ± 106 kg for NL1 to 2366.3 ± 100.1 kg for NL4. KWC was
greatest for NL2 (138.6 kg) followed by NL1 (135 kg); the lowest KWC corresponded to NL4 (96.0 kg) (p < 0.05). TMS values for the middle (1727 ± 94.7 kg) and the high graded GG (1603.5 ± 83.5 kg) were twice those for the low
graded GG cows (828.5 ± 95 kg) (p < 0.05). KWC was also higher for the middle graded group (152.8 kg) than for the low or (104 kg) or the high graded GG (118
kg) (p < 0.05). With better nutrition cows of all GG improved their milk performance but not the calf traits. CBCS was negative
for all GG. The highest BCS lost was for cows in NL1 and NL2 and for cows in the high graded GG (p < 0.05). 相似文献