全文获取类型
收费全文 | 8460篇 |
免费 | 540篇 |
国内免费 | 821篇 |
专业分类
林业 | 282篇 |
农学 | 633篇 |
基础科学 | 64篇 |
1406篇 | |
综合类 | 3476篇 |
农作物 | 496篇 |
水产渔业 | 796篇 |
畜牧兽医 | 1664篇 |
园艺 | 361篇 |
植物保护 | 643篇 |
出版年
2024年 | 54篇 |
2023年 | 152篇 |
2022年 | 279篇 |
2021年 | 364篇 |
2020年 | 361篇 |
2019年 | 410篇 |
2018年 | 293篇 |
2017年 | 464篇 |
2016年 | 513篇 |
2015年 | 392篇 |
2014年 | 488篇 |
2013年 | 484篇 |
2012年 | 678篇 |
2011年 | 693篇 |
2010年 | 560篇 |
2009年 | 530篇 |
2008年 | 441篇 |
2007年 | 509篇 |
2006年 | 405篇 |
2005年 | 338篇 |
2004年 | 217篇 |
2003年 | 168篇 |
2002年 | 140篇 |
2001年 | 127篇 |
2000年 | 98篇 |
1999年 | 99篇 |
1998年 | 79篇 |
1997年 | 71篇 |
1996年 | 59篇 |
1995年 | 51篇 |
1994年 | 49篇 |
1993年 | 38篇 |
1992年 | 38篇 |
1991年 | 41篇 |
1990年 | 30篇 |
1989年 | 37篇 |
1988年 | 15篇 |
1987年 | 24篇 |
1986年 | 8篇 |
1985年 | 7篇 |
1983年 | 3篇 |
1982年 | 1篇 |
1981年 | 3篇 |
1980年 | 2篇 |
1979年 | 2篇 |
1978年 | 1篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1973年 | 1篇 |
1955年 | 2篇 |
排序方式: 共有9821条查询结果,搜索用时 875 毫秒
881.
SMV1号对大豆膜质过氧化及保护酶体系的影响 总被引:1,自引:1,他引:0
本文从大豆膜质过经反应及其保护酶体系的变化,过氧化物酶和苹果酸氮酶同工酶表达牧场生,分析了不同类型的大豆品种对大豆病毒病1号生理小种(SMV1)侵染后的生理生化反应。研究结果表明,大豆品种经SMV1号株系诱导后,感病品种丙二醛(MDA)、越氧化物歧化酶(SOD)活性增加幅较大,抗病品种增加较少,过氧化氢酶(CAT)活性的表达则相反,在花叶病毒侵染条件下,感病与抗病品种过氧化物酶和苹果酸脱氢酶同工酶 相似文献
882.
饲用酶制剂作用机制的研究进展 总被引:6,自引:0,他引:6
分别从饲用酶制剂对畜禽日粮中抗营养因子,消化道内源酶活,微生物菌群,消化器官,外周血液激素水平以及畜禽机体免疫机能等方面的影响,对其改善畜禽生产性能的作用机制进行了探讨,饲用酶主要是通过消除抗营养因子(SNSP,消化酶抑制剂,细胞壁和植酸)和补充内源酶等方式提高日粮养分消化率,并减少有害微生物的过度繁殖,进而改善畜禽生产性能。 相似文献
883.
884.
Blood samples were collected from 98 horses suspected of having borreliosis or granulocytic ehrlichiosis in Connecticut and New York State, USA during 1985, 1995, and 1996. Serum antibodies to Borrelia burgdorferi were detected by an enzyme-linked immunosorbent assay (ELISA), based on whole-cell and recombinant antigens, in 82 (84%) horses. Of the 181 sera tested, 59% were positive, using whole-cell antigens, compared to 48% with protein (p)37 and 35% with VlsE antigens. An ELISA containing either of these fusion proteins can be used as an adjunct to general screening by an ELISA or immunoblotting in animals not vaccinated for this disease. 相似文献
885.
Interleukin-2 is a vital cytokine secreted by activated T lymphocytes, and plays important role in the regulation of cellular
and humoral immunity of animals. In our experiment, IL2 cDNA of the Tibet Pig was first cloned by RT-PCR from ConA-stimulated
lymphocytes in the blood and subcloned into pMD-18 T vector, which then was identified with endonuclease restriction. The
sequencing result showed that Tibet pig IL-2 (TPIL-2) cDNA was 503 bp long (ORF was 465 bp) (Genbank accession number: AY
294018). The recombinant prokaryotic and eukaryotic expression plasmids of the cDNA were then constructed to analyse the ability
to stimulate the proliferation of porcine lymphocytes in vitro. The recombinant porcine IL-2 expressed in the prokaryotic cells was found to be of 43 kDa molecular mass, which was consistent
with a 17.4 kDa protein deduced from the IL-2 cDNA sequence (glutathione S-transferase molecular mass is 26 kDa); the recombinant protein in eukaryotic cells was confirmed by use of specific rabbit
anti-porcine IL-2 serum in an ELISA. The bioactivity of TPIL-2 was detected through MTT colorimetry by stimulating the proliferation
of pig ConA-stimulated blasts in vitro. The results indicate that the TPIL-2 significantly promoted the proliferation of ConA-stimulated blasts of pig. This confirms
that IL-2 cDNA of the Tibet pig was successfully cloned and expressed in prokaryotic and eukaryotic cells, which lays the
foundation for the the preparation of specific recombinant IL-2 protein and development of novel immune adjuvants to raise
the immunity of pigs against various infectious pathogens and increase the immunoprotective efficacy of vaccines. 相似文献
886.
Abhinandan?Deora Yasuyuki?HashidokoEmail author Md.?Tofazzal?Islam Satoshi?Tahara 《European journal of plant pathology / European Foundation for Plant Pathology》2005,112(4):311-322
A total of 150 bacteria were isolated from rhizoplanes of the host and non-host plants of a phytopathogenic Peronosporomycete Aphanomyces cochlioides. Upon screening, 5% of the isolates were evaluated as antagonists as they inhibited radial growth of A. cochlioides AC-5 hyphae in a dual culture assay. In addition, those antagonistic bacteria also induced characteristic morphological alterations in the A. cochlioides AC-5 hyphae that grew towards bacterial colonies. Hyphal morphological alterations observed in AC-5 and other tested strains of Peronosporomycetes included excessive branching, curly growth, unusually longer and pointed tip formation and swelling; all of these were comparable to the alterations induced by known antimicrobial compounds. Among the antagonistic bacteria, Pseudomonas sp. strain EC-S101 induced a unique branching pattern (tree-like) in AC-5 hyphae by continuous apical bifurcation of successive hyphae, where increases in number of branches and hyphal area were linearly correlated with time up to 10 h. Our observations suggested that the pathogen might have lost its ability of normal branch production; however maintained the capability of self-branching. Soluble extracts from the culture fluids of Pseudomonas sp. strain EC-S101 and Stenotrophomonas maltophilia EC-S105 induced similar excessive branching and curly growth in A. cochlioides hyphae as the respective bacterium. These results revealed that bacterial metabolites appeared to be responsible for induction of morphological alterations. Interestingly, the antagonistic bacteria that induced hyphal morphological alterations, also efficiently suppressed in vivo damping-off disease caused by AC-5. We suggest that antagonistic rhizoplane bacteria have the capability to induce diverse morphological alterations in Peronosporomycetes hyphae during in vitro interactions. Hyphal morphological alterations associated with growth inhibition and the induction of characteristic morphological changes indicate antagonistic activity against the Peronosporomycete. 相似文献
887.
888.
猕猴桃果实发育中内源激素水平变化的研究 总被引:30,自引:3,他引:27
应用酶联免疫法(ELISA)测定了美味猕猴桃'Hayward'受精和果实发育中内源生长素(IAA)、玉米素(ZRs)和脱落酸(ABA)水平的变化,以及未受精果实对这些激素变化的影响。结果表明,在花前子房中三类激素已有一定的水平。花后2天完成受精作用,初生胚乳核开始分裂。花后5-7天,合子分裂,果实中AII、ABA含量达到高峰。花后10-40天和80-100天,果实各有一次快速膨大期,前期与果肉中Z 相似文献
889.
890.
感染牛的血清蛋白和某些血清酶的活性,血清总蛋白浓度和GPT、ARG、CHE的活性值,均在正常范围之内,GOT的活性值在虫体移行的末期和出现临床症状的早期明显升高,γ-GT、AMLY和AKP的活性增高与成虫在胆管内定植并与出现临床症状同步。国产丙硫苯咪唑10mg/kg体重剂量驱虫既高效,副作用又 相似文献