全文获取类型
收费全文 | 1082篇 |
免费 | 45篇 |
国内免费 | 97篇 |
专业分类
林业 | 100篇 |
农学 | 108篇 |
基础科学 | 184篇 |
126篇 | |
综合类 | 315篇 |
农作物 | 133篇 |
水产渔业 | 32篇 |
畜牧兽医 | 121篇 |
园艺 | 34篇 |
植物保护 | 71篇 |
出版年
2024年 | 6篇 |
2023年 | 13篇 |
2022年 | 57篇 |
2021年 | 57篇 |
2020年 | 45篇 |
2019年 | 38篇 |
2018年 | 28篇 |
2017年 | 72篇 |
2016年 | 45篇 |
2015年 | 60篇 |
2014年 | 50篇 |
2013年 | 64篇 |
2012年 | 68篇 |
2011年 | 80篇 |
2010年 | 71篇 |
2009年 | 65篇 |
2008年 | 67篇 |
2007年 | 52篇 |
2006年 | 36篇 |
2005年 | 53篇 |
2004年 | 22篇 |
2003年 | 16篇 |
2002年 | 13篇 |
2001年 | 13篇 |
2000年 | 13篇 |
1999年 | 8篇 |
1998年 | 14篇 |
1997年 | 14篇 |
1996年 | 7篇 |
1995年 | 6篇 |
1994年 | 7篇 |
1993年 | 10篇 |
1992年 | 5篇 |
1991年 | 11篇 |
1990年 | 3篇 |
1989年 | 3篇 |
1988年 | 4篇 |
1987年 | 5篇 |
1986年 | 2篇 |
1984年 | 5篇 |
1983年 | 2篇 |
1981年 | 1篇 |
1978年 | 4篇 |
1977年 | 1篇 |
1974年 | 1篇 |
1972年 | 1篇 |
1969年 | 1篇 |
1968年 | 1篇 |
1966年 | 1篇 |
1955年 | 2篇 |
排序方式: 共有1224条查询结果,搜索用时 578 毫秒
91.
埃及血吸虫和曼氏血吸虫四跨膜孤儿受体(trispanning orphan receptors,TOR)受体可以结合补体C2a,可能在血吸虫免疫逃避过程中起重要作用。为研究日本血吸虫TOR受体的特性和功能,利用PCR扩增到Sj TOR基因并进行了生物信息学分析;同时克隆了Sj TOR基因N端第一个膜外区(ed1)基因,构建了重组质粒p ET-28a-Sj TOR-ed1,在大肠杆菌BL21(DE3)中诱导表达后用组蛋白亲和层析纯化获得重组蛋白Sj TOR-ed1,Western blot结果显示r Sj TOR-ed1能被日本血吸虫阳性小鼠血清识别。该研究为进一步开展研究日本血吸虫TOR受体的功能提供了基础。 相似文献
92.
R. M. Wallace D. Stanek S. Griese D. Krulak N. M. Vora L. Pacha V. Kan M. Said C. Williams T. H. Burgess S. S. Clausen C. Austin J. Gabel M. Lehman L. N. Finelli G. Selvaggi P. Joyce F. Gordin D. Benator A. Bettano S. Cersovsky C. Blackmore S. V. Jones B. D. Buchanan A. I. Fernandez D. Dinelli K. Agnes A. Clark J. Gill M. Irmler D. Blythe K. Mitchell T. J. Whitman M. J. Zapor S. Zorich C. Witkop P. Jenkins P. Mora D. Droller S. Turner L. Dunn P. Williams C. Richards G. Ewing K. Chapman C. Corbitt T. Girimont R. Franka S. Recuenco J. D. Blanton K. A. Feldman 《Zoonoses and public health》2014,61(8):560-570
This article describes and contrasts the public health response to two human rabies cases: one organ recipient diagnosed within days of symptom onset and the transplant donor who was diagnosed 18 months post‐symptom onset. In response to an organ‐transplant‐related rabies case diagnosed in 2013, organ donor and recipient investigations were conducted by multiple public health agencies. Persons with potential exposure to infectious patient materials were assessed for rabies virus exposure. An exposure investigation was conducted to determine the source of the organ donor's infection. Over 100 persons from more than 20 agencies spent over 2700 h conducting contact investigations in healthcare, military and community settings. The 564 persons assessed include 417 healthcare workers [5.8% recommended for post‐exposure prophylaxis (PEP)], 96 community contacts (15.6% recommended for PEP), 30 autopsy personnel (50% recommended for PEP), and 21 other persons (4.8% recommended for PEP). Donor contacts represented 188 assessed with 20.2% recommended for PEP, compared with 5.6% of 306 recipient contacts recommended for PEP. Human rabies cases result in substantial use of public health and medical resources, especially when diagnosis is delayed. Although rare, clinicians should consider rabies in cases of encephalitis of unexplained aetiology, particularly for cases that may result in organ donation. 相似文献
93.
Farm-level land diversity of smallholders with limited input resources during urbanization in Taiwan
During urbanization in Taiwan, the input resources of farmland are always compressed by other land uses; the landscape diversity of small farms is emphasized in rural areas. To determine the extent to which diversity in farmland use corresponds with urbanization, a goal programming study was established. This was analysed by investigating several assumed options of diversification that are available to the smallholder. The results revealed that the existing pattern of land use among members of the Taoyuan Irrigation Association (TIA) is constrained mainly by the basic requirement for paddy fields. The value of the gross benefit of farmer could be reduced by 20 %, and that of landscape diversity could increase by 67 % in cases of which the paddy field is reduced for other land use through the optimal allocation of the studied land use was implemented. Sensitivity analysis indicated that the existing pattern of land use can survive the potential shortage of input resources to adapt urbanization through the diversified land use. Among the options for diversified land use, a varied landscape can be created that will both enrich the recreational space, and enhance the reasonable consumption of limited input resources in small farm. 相似文献
94.
小麦白粉病是世界范围内广泛流行的小麦叶部真菌病害,显著影响小麦的产量和品质。由于现有品种的白粉病抗性不断丧失,使得进一步挖掘新的白粉病抗源及抗病基因十分重要。本研究以硬粒小麦品种UC1113和Kofa构建的包含93个株系的F8代RIL群体为材料,利用235个多态性标记构建遗传图谱,并结合白粉病成株抗性表型数据,对4个环境下的白粉病成株抗性进行QTL定位。结果表明,在RIL群体中共定位到4个与白粉病成株抗性相关的QTL,分别位于1AL、4AL(2)和5AL染色体上。其中,来自UC1113的3个QTL( QPm.hnau-1AL 、 QPm.hnau-4AL.1 和 QPm.hnau-4AL.2 )为新的白粉病成株抗性QTL。本研究为小麦白粉病抗性基因挖掘和抗病育种提供了重要信息。 相似文献
95.
近年来福建省设施蔬菜发展较快.通过总结福建省设施蔬菜生产现状、设施类型及应用性能,分析设施蔬菜产业发展过程中存在的问题,并提出对策,以期为设施蔬菜产业良性、高效发展提供参考. 相似文献
96.
97.
分别采用组织块法和消化法2种接种方法进行银狐垂体细胞系构建研究。在消化法中使用不同浓度的胰蛋白酶来检验效果,同时在原代培养期使用反复差速贴壁法纯化,传代培养期结合使用反复差速贴壁以及两步消化法进行处理。结果表明:组织块法接种后成纤维细胞生长明显,原代培养后期成纤维细胞已为主要细胞;降低胰蛋白酶浓度能降低对细胞损伤,但消化时间会增长;采用消化法接种在抑制成纤维细胞生长方面效果好于组织块法。纯化效果上,结合反复差速贴壁法与两步消化法处理后获得了较好的效果,在原代培养时期能较好去除成纤维细胞并通过持续使用该方法可在传二代后获得较高纯度的细胞,纯度能达到80%以上,能够建立细胞系。 相似文献
98.
99.
N C Kan 《Avian diseases》1991,35(4):941-949
Avian carcinoma retrovirus MH2 induces leukemia and solid tumors in chickens and transforms fibroblasts and macrophages in vitro. The genome of MH2 consists of two oncogenes, v-mht/mil and v-myc. Most of the transforming activity of MH2 is attributed to the v-myc oncogene. In contrast, the v-mht/mil oncogene alone does not induce a fully transformed phenotype of avian primary fibroblasts in vitro. It was shown previously that v-mht/mil is the avian homology of the v-raf oncogene in murine sarcoma retrovirus 3611. Because the v-raf oncogene transforms murine fibroblasts very efficiently, the present study tested the hypothesis that an extra segment in the 5' end of v-mht/mil relative to v-raf suppressed the fibroblast-transforming activity of v-mht/mil. By introducing an in-frame deletion of 195 nucleotides into the 5' end of v-mht/mil, the results demonstrate that in the presence of an inactive v-myc oncogene, the 5'-deleted v-mht/mil oncogene fails to transform chicken embryo fibroblasts. Therefore, it is likely that avian primary fibroblasts lack a cellular component that serves as a critical substrate/target for v-mht/mil-induced cellular transformation. 相似文献
100.