全文获取类型
收费全文 | 25634篇 |
免费 | 1197篇 |
国内免费 | 2996篇 |
专业分类
林业 | 3007篇 |
农学 | 3698篇 |
基础科学 | 2054篇 |
4407篇 | |
综合类 | 7657篇 |
农作物 | 1456篇 |
水产渔业 | 1005篇 |
畜牧兽医 | 3757篇 |
园艺 | 926篇 |
植物保护 | 1860篇 |
出版年
2024年 | 69篇 |
2023年 | 293篇 |
2022年 | 686篇 |
2021年 | 1050篇 |
2020年 | 1003篇 |
2019年 | 902篇 |
2018年 | 656篇 |
2017年 | 932篇 |
2016年 | 861篇 |
2015年 | 1182篇 |
2014年 | 1087篇 |
2013年 | 1351篇 |
2012年 | 1619篇 |
2011年 | 1658篇 |
2010年 | 1606篇 |
2009年 | 1478篇 |
2008年 | 1400篇 |
2007年 | 1477篇 |
2006年 | 1356篇 |
2005年 | 1155篇 |
2004年 | 564篇 |
2003年 | 513篇 |
2002年 | 458篇 |
2001年 | 467篇 |
2000年 | 565篇 |
1999年 | 698篇 |
1998年 | 619篇 |
1997年 | 538篇 |
1996年 | 518篇 |
1995年 | 512篇 |
1994年 | 469篇 |
1993年 | 418篇 |
1992年 | 392篇 |
1991年 | 303篇 |
1990年 | 248篇 |
1989年 | 208篇 |
1988年 | 165篇 |
1987年 | 92篇 |
1986年 | 63篇 |
1985年 | 32篇 |
1984年 | 16篇 |
1983年 | 35篇 |
1982年 | 18篇 |
1981年 | 24篇 |
1980年 | 11篇 |
1979年 | 7篇 |
1974年 | 9篇 |
1965年 | 6篇 |
1964年 | 6篇 |
1963年 | 8篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
81.
Avian reoviruses (ARVs) can result in disease and economic losses in the poultry industry. Vaccines against ARV may not provide full protection and can cause adverse reactions. The coding sequence of the sigma C protein from strain S1133 of avian reovirus was expressed in Schizasaccharomyces pombe. Sigma C protein expression was demonstrated by Western blotting, and the protein was evaluated for its ability to protect specific-pathogen-free (SPF) chickens against challenge with the virulent S1133 strain. Serologic and challenge-infection data showed the efficacy of the recombinant vaccine administered orally each week for 3 consecutive wk. Sigma C protein induced antibody, as determined by enzyme-linked immunosorbent assay. Percentage (%) protection induced by the low dose (125 microg purified yeast-expressed sigma C protein/chicken) or the high dose (250 microg purified yeast-expressed sigma C protein/chicken) was 64 and 91, respectively. The commercial vaccine administered once or twice provided 82% protection. Results supported the feasibility of a plant-derived vaccine for use in poultry immunization schemes. 相似文献
82.
不同的干燥工艺对荷花蜂花粉功能成分的影响 总被引:1,自引:0,他引:1
探讨了5种干燥工艺对荷花蜂花粉功能成分的影响。微波干燥的干燥效率最高,60%火力处理540s可使水分从31.41%降到6.42%;干燥方式对荷花蜂花粉蛋白质影响较小;微波干燥后总黄酮提取率最高,为13.20mg/g;真空冷冻干燥后维生素C和过氧化氢酶含量最高,分别为48.89mg/100g和29.86mg/g·min。总的来说,真空冷冻干燥对荷花蜂花粉的功能成分影响最小;常压恒温干燥对功能成分影响较小、工艺简单、对设备要求低,宜于大规模应用于实际生产中。 相似文献
83.
Avian leukosis virus subgroup A (ALV‐A) is a retrovirus which infects egg‐type chickens and is the main pathogen of lymphoid leukosis (LL) and myeloid leukosis (ML). In order to greatly enhance the diagnosis and treatment of clinical avian leukemia, two monoclonal antibodies (MAbs) to ALV‐A were developed by fusion between SP2/0 and spleen cells from mice immunized with expressed ALV‐A env‐gp85 protein. Using immunofluorescence assay (IFA), two MAbs reacted with ALV‐A, but not with subgroups B and J of ALV. Western blot tests showed that molecular weight of ALV‐A envelope glycoprotein recognized by MAbs was about 53 kD. Isotyping test revealed that two MAbs (A5C1 and A4C8) were IgG1 isotypes. These MAbs can be used for diagnosis and epidemiology of ALV‐A. 相似文献
84.
85.
改革开放20多年来。黔西南州农业获得了长足发展,在产品供求关系、生产目标、增长方式、经营形式、产业关联等方面都发生了显著变化,进入了农产品供求基本平衡,以提高品质、优化结构和增加农民收入为主,注重传统投入与资本集约和技术集约相结合的优化发展阶段。加入WTO,对于我州正处在发展新阶段的农业和农村经济来说。是一次重要的机遇和挑战。面对激烈的国际、国内市场竞争。在西部大开发中,为了改善生态环境,调整农业结构,增加农民收入,州委、州政府决定把草地畜牧业作为我州农业和农村产业结构调整的重点。制定了百万亩草地畜牧业发展规划。出台了加快草地畜牧业发展的实施意见。 相似文献
86.
87.
88.
J.‐J. Luo H.‐W. Song B. Zhang L.‐L. Li Y.‐G. Chen Y. Peng L.‐Z. Wu J.‐X. Fan J.‐S. Zhan 《Journal of animal physiology and animal nutrition》2014,98(3):517-521
To clone adiponectin (ADPN) gene from Shaziling porcine adipocyte and construct its eukaryotic expression vector, total RNA was extracted from subcutaneous fatty tissue. One pair of specific primers was designed by Primer 5.0 software according to the sequence of ADPN gene of porcine available in GenBank. The ADPN gene was amplified by PCR from cDNA and cloned into pMD18‐T vector to construct recombinant clonal vector pMD‐ADPN, sequenced and analysed. A recombinant expression plasmid pPICZaA‐ADPN was constructed by subcloning the cloned ADPN gene into the linearized pPICZaA vector. Then, the plasmid pPICZaA‐ADPN was expressed in Pichia pastoris (GS115) by electrotransformation. Western blot and Bradford analysis were used to determine the target protein induced by methanol. Results showed that the genome size of ADPN was 732 bp and encoded 244 amino acid, the nucleotide sequence of ADPN shared 100% identity with that of porcine available in GenBank. Western blot and Bradford analysis showed that the recombinant ADPN was expressed in GS115 correctly and has certain immune activity. The expression level of ADPN was 28.5 μg/ml. In conclusion, the recombinant ADPN could express in eukaryotic expression vector pPICZaA‐ADPN constructed in this study effectively. 相似文献
89.
一、采取寄养措施的前提1.母犬产后死亡。2.母犬产后乳汁分泌过少,哺育较多的仔犬有困难。3.母犬产仔过多,超过其有效哺乳头数。4.不同品种仔犬的经济价值不同,利用奶水较好的母犬来哺育经济价值高的仔犬。二、寄养方法主要有直接寄养和交叉寄养两种方法。1.直接寄养是指直接把 相似文献
90.