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排序方式: 共有846条查询结果,搜索用时 15 毫秒
61.
Shi-chao WANG Jin-zhou WANG Ya-wen ZHAO Yi REN Ming-gang XU Shu-xiang ZHANG Chang-ai LU 《农业科学学报》2019,18(11):2619-2627
The contribution percentage of inherent soil productivity (CPISP) refers to the ratio of crop yields under no-fertilization versus under conventional fertilization with the same field management. CPISP is a comprehensive measure of soil fertility. This study used 1 086 on-farm trials (from 1984–2013) and 27 long-term field experiments (from 1979–2013) to quantify changes in CPISP. Here, we present CPISP3 values, which reflect the CPISP states during the first three years after site establishment, for a series of sites at different locations in China collected in 1984–1990 (the 1980s), 1996–2000 (the 1990s), and 2004–2013 (the 2000s). The results showed that the average CPISP3 value for three crops (wheat, rice, and maize) was 53.8%. Historically, the CPISP3 in the 1990s (57.5%) was much higher than those in the 1980s (50.3%), and the 2000s (52.0%) (P≤0.05). Long-term no-fertilization caused CPISP levels to gradually decline and then stabilize; for example, in a mono-cropping system with irrigation, the CPISP values in Northwest and Northeast China declined by 4.5 and 4.0%, respectively, each year for the first ten years, but subsequently, the CPISP values stabilized. In contrast, the CPISP for upland crops in double-cropping systems continued to decrease at a rate of 1.1% per year. The CPISP for upland-paddy cropping decreased very slowly (0.07% per year), whereas the CPISP for paddy cropping decreased sharply (3.1% per year, on average) for the first two years and then remained steady during the following years. Therefore, upland crops in double-cropping systems consume the most inherent soil productivity, whereas paddy fields are favourable for maintaining a high level of CPISP. Overall, our results demonstrate a need to further improve China's CPISP3 values to meet growing productivity demands. 相似文献
62.
Xing ZHOU Yan-hong LU Yu-lin LIAO Qi-dong ZHU Hui-dan CHENG Xin NIE Weidong CAO Jun NIE 《农业科学学报》2019,18(10):2381-2392
The double-rice cropping system is a very important intensive cropping system for food security in China. There have been few studies of the sustainability of yield and accumulation of soil organic carbon(SOC) in the double-rice cropping system following a partial substitution of chemical fertilizer by Chinese milk vetch(Mv). We conducted a 10-year(2008–2017) field experiment in Nan County, South-Central China, to examine the double-rice productivity and SOC accumulation in a paddy soil in response to different fertilization levels and Mv application(22.5 Mg ha~(–1)). Fertilizer and Mv were applied both individually and in combination(sole chemical fertilizers, Mv plus 100, 80, 60, 40, and 0% of the recommended dose of chemical fertilizers, labeled as F100, MF100, MF80, MF60, MF40, and MF0, respectively). It was found that the grain yields of double-rice crop in treatments receiving Mv were reduced when the dose of chemical fertilizer was reduced, while the change in SOC stock displayed a double peak curve. The MF100 produced the highest double-rice yield and SOC stock, with the value higher by 13.5 and 26.8% than that in the F100. However, the grain yields increased in the MF80(by 8.4% compared to the F100), while the SOC stock only increased by 8.4%. Analogous to the change of grain yield, the sustainable yield index(SYI) of double rice were improved significantly in the MF100 and MF80 compared to the F100, while there was a slight increase in the MF60 and MF40. After a certain amount of Mv input(22.5 Mg ha~(–1)), the carbon sequestration rate was affected by the nutrient input due to the stimulation of microbial biomass. Compared with the MF0, the MF100 and MF40 resulted in a dramatically higher carbon sequestration rate(with the value higher by 71.6 and 70.1%),whereas the MF80 induced a lower carbon sequestration rate with the value lower by 70.1% compared to the MF0. Based on the above results we suggested that Mv could partially replace chemical fertilizers(e.g., 40–60%) to improve or maintain the productivity and sustainability of the double-rice cropping system in South-Central China. 相似文献
63.
对试验药剂80%吡蚜酮·烯啶虫胺WG和对照药剂25%噻嗪酮WP防治稻飞虱效果进行了田间药效试验,结果表明:80%吡蚜酮·烯啶虫胺WG对水稻褐飞虱和白背飞虱具有很好的防治效果,速效性好、持效期长,且对水稻安全.每667 m2用药量为12 g时,药后3d、7d、14d、21 d防效分别达84.97%、89.19%、91.26%、92.28%;极显著优于对照药剂25%噻嗪酮WP,生产上可大面积推广应用. 相似文献
64.
65.
RICHARD G. HARVEY TREVOR J. WHITBREAD LUIS FERRER JOHN E. COOPER 《Veterinary dermatology》1992,3(1):13-19
Abstract— Epidermotropic cutaneous T-cell lymphoma was diagnosed in six Syrian hamsters (Mesocricetus auratus) with a generalised dermatosis characterised by pruritus, alopecia and exfoliative erythroderma. Plaques and nodules were evident in one animal. Clinical and histopathological findings were suggestive of mycosis fungoides and electron microscopical investigations in one case were supportive. Immuno-histochemical stains for CD3 antigen were strongly positive in all cases. Résumé— Un lyphome T cutané a été diagnostiqué chez six hamsters de Sibérie (Mesocricetus auratus) avec une dermatose généralisée, caractérisée par un prurit, une alopécle et une érythrodermie exfoliative. Des plaques et des nodules ont été observées sur un animal. Les données cliniques et histopathologiques étaient évocatrices d'un mycosis fungoïdes et les examens en microscopie électronique étaient compatibles dans un cas. Les marquages immuno-histochimiques de l'antigène CD3 étaient très positifs dans tous les cas. Zusammenfassung— Bei sechs Syrischen Goldhamstern (Mesocricetus auratus) wurde ein epidermotropes kutanes T-Zell-Lymphom mit einer generalisierten Dermatose diagnostiziert, die durch Pruritus, Alopezie und eine exfoliative Erythrodermie gekennzeichnet war. Bei einem Tier traten auch Plagues und Knoten auf. Die klinischen und histopathologischen Befunde deuteten auf Mycosis fungoides hin. Elektronenmikroskopische Untersuchungen unterstützten diesen Verdacht in einem Fall. Immunhistochemische Färbungen auf CD3-Antigen waren bei alien Fallen stark positiv. Resumen En un grupo de seis hamsters de siria, (Mesocricetus auratus), se diagnosticó limfoma epidermotrópico cutáneo de linfocitos T, presentando una dermatosis generalizada de tipo pruriginoso, acompañada de alopecia y eritroderma exfoliativo. Las placas y nódulos fueron evidentes en uno de los animales. Los estudios clinicos e histopatológicos indicaron una micosis fungoide, y las investigaciones de microscopía, en uno de los caseos, pareció indicar lo mismo. La tintura inmuno-histoquimica para el antígeno CD3 resultó claramente positiva en todod los casos. 相似文献
66.
Reticuloendotheliosis virus (REV) causes the atrophy of immune organs and immuno-suppression in chickens, but the underlying molecular mechanism of the immune response after infection by REV is not well understood. Presently, the RNA-seq was used to analyze the regulation of immune response to REV in chicken lymphocytes from peripheral blood. Overall, 134 differentially expressed long non-coding RNAs (lncRNAs) between cells with REV infection or without in vitro were screened. Based on the differentially expressed protein-coding genes, the nucleotide-binding oligomerization domain (NOD)-like receptor pathway related to immune regulation was enriched. Two lncRNAs (L11530 and L09863) were predicted to target the NOD1 and tumor necrosis factor receptor-associated factor 5 (TRAF5) gene, respectively, which are involved in the NOD-like receptor pathway with cis-regulation way. The in vitro results revealed the significantly up-regulated (P<0.01) levels of lncRNA-L11530 and its target gene, NOD1, and the significantly down-regulated (P<0.05) levels of lncRNA-L09863 and its target gene, TRAF5, in lymphocytes after REV infection. These changes also occurred in vivo in blood lymphocytes of chickens infected with REV. Further, L09863 and L11530 were respectively interfered, the expression levels of their target genes NOD1 or TRAF5 were significantly down-regulated, accompanied by the change of IL-8 and IL-18 secretions in lymphocytes. The NOD-like receptor pathway appears to be important in the immune response to REV, LncRNA-11530 and IncRNA-09863 might involve in the immune regulation on REV infection by targeting NOD1 or TRAF5 in blood lymphocytes of chickens. Our findings reveal a new regulation of lncRNAs (L11530 and L09863) on immunity in chicken peripheral blood lymphocytes for REV infection by changing the expression of the target genes via the NOD-like receptor pathway. 相似文献
67.
2年新植2年宿根区域试验和多年生产示范表明,闽糖86-2121是个萌芽率一般,分蘖率强,高产稳产、含糖量高、蔗糖分一般,中晚熟、宿根性强、抗旱抗病力强的甘蔗新品种,栽培上要适当增加下种量,及早追肥,宿根蔗宜早松蔸管理。 相似文献
68.
Cry1Ai-h-loop 2 is a mutant of Cry1Ai constructed by exchanging loop 2 from Cry1Ah protein and shows insecticidal activity against Helicoverpa armigera. The toxicity of Cry1 Ai-h-loop 2, in contrast to the very low toxicity of Cry1Ai, is closely associated with the eleven residues in the loop 2 region. To characterize the key sites of loop 2 in Cry1Ai-h-loop 2, alaninesubstituted mutants were generated. The toxicity of these mutants against H. armigera indicated that dual-mutant on Gly373 and Asn375 caused a significant decrease in toxic activity. ELISA binding and competition binding assays demonstrated that the reduction of toxicity in the mutant of interest was correlated with decreased binding affinity. 相似文献
69.
CD147基因在家兔肠道的克隆与结构预测 总被引:2,自引:1,他引:1
基于电子延伸序列,克隆并分析兔CD147基因.采用兔十二指肠黏膜组织提取总RNA,进行RT-PCR反应,测序并进行结构预测.克隆的兔CD147基因包含一个完整的开放阅读框架,全长为810 bp,编码由270个氨基酸残基组成的CD147前体蛋白,推导的氨基酸序列信号肽为1~16个氨基酸.氨基酸序列与牛、人、褐鼠、野猪的同源性分别为62.5%,65.9%,59.5%和66.3%,三级结构预测表明CD147具有2个免疫球蛋白类似区.试验成功克隆了兔CD147基因,注册到GenBank(Accession.EU650668),并预测其三级结构,为进一步研究其生物学功能奠定基础. 相似文献
70.
2002年调查表明,黔东南州烟叶调拨站烟叶仓储库区危害烟叶的主要害虫种类有烟草粉螟和烟草甲2种。选用几种杀虫剂对其进行防治效果比较试验,结果表明:强敌-312WP 50 g 80%敌敌畏EC 250 mL处理区防治效果最好,药后7 d,防治效果达93.56%~96.79%,平均为95.18%;药后15 d,防治效果达90.67%~92.82%,平均为91.75%;药后30 d,防治效果达88.20%~89.53%,平均为88.87%,均显著高于其它4个处理区的防治效果。强敌-312WP 50 g 80%敌敌畏EC 250 mL在大面积防治示范区对2种害虫的防治效果,在仓储烟叶区,空仓地面和包装麻片上的防治效果相近,药后7 d,防治效果在89.66%~93.75%,平均为91.29%;药后30 d,防治效果达92.5%~100%,平均为95.19%;药后90 d,防治效果仍保持在75.00%~86.67%,平均为81.03%。试验示范证明,强敌-312WP 50 g 80%敌敌畏EC 250 mL是防治危害仓储烟叶烟草粉螟和烟草甲的最有效药剂和浓度。该药剂符合高效、低毒、低残留,对人畜安全的现代农药要求,在储烟库区有较好的推广前景。 相似文献