全文获取类型
收费全文 | 8704篇 |
免费 | 454篇 |
国内免费 | 652篇 |
专业分类
林业 | 1220篇 |
农学 | 661篇 |
基础科学 | 366篇 |
1469篇 | |
综合类 | 3806篇 |
农作物 | 419篇 |
水产渔业 | 287篇 |
畜牧兽医 | 1093篇 |
园艺 | 213篇 |
植物保护 | 276篇 |
出版年
2024年 | 56篇 |
2023年 | 168篇 |
2022年 | 270篇 |
2021年 | 282篇 |
2020年 | 287篇 |
2019年 | 375篇 |
2018年 | 205篇 |
2017年 | 368篇 |
2016年 | 464篇 |
2015年 | 362篇 |
2014年 | 485篇 |
2013年 | 525篇 |
2012年 | 685篇 |
2011年 | 694篇 |
2010年 | 513篇 |
2009年 | 503篇 |
2008年 | 477篇 |
2007年 | 529篇 |
2006年 | 416篇 |
2005年 | 335篇 |
2004年 | 249篇 |
2003年 | 206篇 |
2002年 | 169篇 |
2001年 | 143篇 |
2000年 | 140篇 |
1999年 | 126篇 |
1998年 | 90篇 |
1997年 | 76篇 |
1996年 | 76篇 |
1995年 | 81篇 |
1994年 | 79篇 |
1993年 | 76篇 |
1992年 | 62篇 |
1991年 | 58篇 |
1990年 | 58篇 |
1989年 | 39篇 |
1988年 | 27篇 |
1987年 | 28篇 |
1986年 | 8篇 |
1985年 | 4篇 |
1984年 | 4篇 |
1983年 | 3篇 |
1982年 | 1篇 |
1977年 | 4篇 |
1975年 | 1篇 |
1973年 | 1篇 |
1956年 | 2篇 |
排序方式: 共有9810条查询结果,搜索用时 0 毫秒
31.
32.
M. Pettersson S. Eriksson 《Acta Agriculturae Scandinavica, Section A - Animal Sciences》2016,66(4):183-189
There is substantial international influence on the Swedish Warmblood (SWB) sport horse population. The SWB Association suspects that imported horses are pre-selected based on their anticipated performance level, which could lead to biased estimated breeding values (EBVs) for stallions. This study examined different strategies to handle records for imported horses in the genetic evaluation. The stallions were evaluated for 10 traits using 3 different EBV estimation methods that were compared based on ranking comparisons of stallions, accuracy, correlations and absolute differences between EBVs. The results showed that the stallions’ EBVs were affected by imported offspring which, as a group, had higher average scores than horses born in Sweden. Sire EBVs differed by up to 0.6 genetic standard deviation of the trait between methods for stallions with >50% imported offspring. Excluding imported offspring lowered the accuracies and caused larger re-ranking compared with including a fixed effect of origin in the model. 相似文献
33.
34.
This paper points out the shortcoming of the existing project break-even analysis method. A new improved method-the dynamic project break-even analysis method has been put forward. 相似文献
35.
Nonlinear characteristic of servo value is the important factor influencing hydraulic system, the model of electro-hydraulic servo pressure control system is designed. In this model, flux-equation of servo valve is specially applied and some non-linear characteristics are considered. Furthermore, SIMULINK toolbox of MATLAB language software is applied to solve mathematic model and simulation curves of some variables are obtained. The calculation results are in good agreement with the experimental results. 相似文献
36.
37.
Appraise the Traditional stocks inherent value models ,and point out their shortcomings.Then a improved stocks inherent value model which emphasize growth of listed Company is set up.The improved model can explain the situation for the times of knowledge economy.Finally, the growth of listed company and is studied a analytic Hierarchy Process model to appraise the growth of listed company is set up. 相似文献
38.
39.
40.
Zou Jianbo 《保鲜与加工》1992,(4)
In this paper, the concept of basic for linear vector extreme value problem is introduced in the partially ordered vector space. Some properties and results of the linear programming are generalized. And the existaence therom of basic optimal solution is proved. 相似文献