全文获取类型
收费全文 | 3817篇 |
免费 | 174篇 |
国内免费 | 393篇 |
专业分类
林业 | 405篇 |
农学 | 602篇 |
基础科学 | 338篇 |
544篇 | |
综合类 | 1105篇 |
农作物 | 216篇 |
水产渔业 | 159篇 |
畜牧兽医 | 597篇 |
园艺 | 163篇 |
植物保护 | 255篇 |
出版年
2024年 | 22篇 |
2023年 | 49篇 |
2022年 | 109篇 |
2021年 | 162篇 |
2020年 | 140篇 |
2019年 | 142篇 |
2018年 | 76篇 |
2017年 | 151篇 |
2016年 | 131篇 |
2015年 | 161篇 |
2014年 | 149篇 |
2013年 | 195篇 |
2012年 | 219篇 |
2011年 | 213篇 |
2010年 | 252篇 |
2009年 | 243篇 |
2008年 | 200篇 |
2007年 | 240篇 |
2006年 | 195篇 |
2005年 | 195篇 |
2004年 | 89篇 |
2003年 | 90篇 |
2002年 | 88篇 |
2001年 | 98篇 |
2000年 | 91篇 |
1999年 | 94篇 |
1998年 | 83篇 |
1997年 | 74篇 |
1996年 | 70篇 |
1995年 | 58篇 |
1994年 | 81篇 |
1993年 | 44篇 |
1992年 | 36篇 |
1991年 | 21篇 |
1990年 | 27篇 |
1989年 | 33篇 |
1988年 | 21篇 |
1987年 | 12篇 |
1986年 | 10篇 |
1985年 | 4篇 |
1984年 | 3篇 |
1983年 | 1篇 |
1982年 | 4篇 |
1981年 | 4篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1972年 | 1篇 |
1971年 | 1篇 |
排序方式: 共有4384条查询结果,搜索用时 15 毫秒
101.
Jianpeng Gao Mingxing Tian Yanqing Bao Peng Li Jiameng Liu Chan Ding Shaohui Wang Tao Li Shengqing Yu 《Veterinary research》2016,47(1)
Brucellosis, caused by a facultative intracellular pathogen Brucella, is one of the most prevalent zoonosis worldwide. Host infection relies on several uncanonical virulence factors. A recent research hotpot is the links between carbon metabolism and bacterial virulence. In this study, we found that a carbon metabolism-related pyruvate kinase (Pyk) encoded by pyk gene (locus tag BAB_RS24320) was associated with Brucella virulence. Determination of bacterial growth curves and resistance to environmental stress factors showed that Pyk plays an important role in B. abortus growth, especially under the conditions of nutrition deprivation, and resistance to oxidative stress. Additionally, cell infection assay showed that Pyk is necessary for B. abortus survival and evading fusion with lysosomes within RAW264.7 cells. Moreover, animal experiments exhibited that the Pyk deletion significantly reduced B. abortus virulence in a mouse infection model. Our results elucidated the role of the Pyk in B. abortus virulence and provided information for further investigation of Brucella virulence associated carbon metabolism. 相似文献
102.
A peptide of foot-and-mouth disease virus serotype Asia1 generating a neutralizing antibody response, and an immunostimulatory peptide 总被引:2,自引:0,他引:2
Wang JL Liu MQ Han J Chen WZ Cong W Cheng G Gao YH Lu YG Chen JL Zuo XP Yan WY Zheng ZX 《Veterinary microbiology》2007,125(3-4):224-231
The epitopes of the capsid of foot-and-mouth disease virus (FMDV) play important roles in the construction of highly immunogenic subunit vaccines. However few epitopes have been found for FMDV serotype Asia1. In this study we screened for epitopes of the VP1 and VP2 proteins of FMDV serotype Asia1 isolate, YNBS/58. Fragments consisting of amino acids 133-163 of VP1 and amino acids 1-33 of VP2 contained epitopes, and both induced lymphoproliferation in guinea pigs. Only the VP1 fragment induced neutralizing antibodies but the VP2 peptide dramatically increased the neutralizing antibody response induced by the VP1 peptide. 相似文献
103.
104.
Zhu Caicao Wang Hongen Gong JianxiaoYu Shixing 《保鲜与加工》1993,(6):51-57
In this paper,the mill stand and the rolled piece were studied as a system. Based on the disoreted masses and the deformation of bending curve of the roller and roll housing, according to Rayleigh method,the equivalent mass and and the equivalent stiffness of the mode were solved,and set up a multiple degree of freedom vibration dynamic model. And also did theoretical analysis and calculation with an exapmle of the 4200 thick plate rolling mills. 相似文献
105.
Sheng Guangmin Gong Shihong Zhu Jinfu 《保鲜与加工》1989,(2):67-72
In this paper, the strain fatigue: crack propagation rates of vanadium bearing HSLA steel with different micro-structures are measured under constant load conditions, and the relationship between the crack propagation rate and the microstructures of steel is also studied. 相似文献
106.
Based on the analysis and study on some existed models for two-dimensional Guillotine Cutting-Stock problem, it is pointed out that some kinds of the models may miss some good cutting patterns,and some may result in inadequate solutions because of only considering the patterns with the smallest waste. A kind of revised two-dimensional cutting-stock models are developed,which transform the two-dimensional problem into the one-dimensional one using the dimension-decreasing heuristic method and whose initial patterns are considered comprehensively. In this kind of models, not only the least waste,but also the other constraints,such as the demands and the relative area of the order plates are considered. 相似文献
107.
Gong Jian Liu Fei Xu Zhongjun 《保鲜与加工》1997,(1):92-97
Based on alalysing the mathematical models for one dimensional equal stock cutting problem,a knapsack column generation algorithm has been constructed,which is a successive approximate algorithm for the practical engineering.In the end of this paper,some computational examples have been presented,which show that the convergence and optimum results of the algorithm are quite good. 相似文献
108.
研究表明:圆果种比长果种工艺纤维支数高65公支左右;品种间差异极显著;工艺纤维细度与单株原麻重等5个经济性状呈极显著负相关,与出麻率等性状呈显著正相关;麻株各部位中以中部工艺纤维支数最高,梢部次之,基部最低;适时播种、适当密植、适量适时施肥,适时早收等栽培技术措施能提高工艺纤维支数。通过对构成产量和工 相似文献
109.
110.