全文获取类型
收费全文 | 3375篇 |
免费 | 167篇 |
国内免费 | 185篇 |
专业分类
林业 | 859篇 |
农学 | 197篇 |
基础科学 | 302篇 |
553篇 | |
综合类 | 1380篇 |
农作物 | 24篇 |
水产渔业 | 75篇 |
畜牧兽医 | 73篇 |
园艺 | 219篇 |
植物保护 | 45篇 |
出版年
2024年 | 16篇 |
2023年 | 66篇 |
2022年 | 94篇 |
2021年 | 88篇 |
2020年 | 84篇 |
2019年 | 113篇 |
2018年 | 51篇 |
2017年 | 89篇 |
2016年 | 132篇 |
2015年 | 85篇 |
2014年 | 223篇 |
2013年 | 207篇 |
2012年 | 357篇 |
2011年 | 316篇 |
2010年 | 295篇 |
2009年 | 244篇 |
2008年 | 248篇 |
2007年 | 222篇 |
2006年 | 166篇 |
2005年 | 141篇 |
2004年 | 93篇 |
2003年 | 70篇 |
2002年 | 63篇 |
2001年 | 45篇 |
2000年 | 35篇 |
1999年 | 23篇 |
1998年 | 17篇 |
1997年 | 13篇 |
1996年 | 24篇 |
1995年 | 18篇 |
1994年 | 21篇 |
1993年 | 16篇 |
1992年 | 12篇 |
1991年 | 10篇 |
1990年 | 8篇 |
1989年 | 8篇 |
1988年 | 8篇 |
1987年 | 4篇 |
1985年 | 1篇 |
1963年 | 1篇 |
排序方式: 共有3727条查询结果,搜索用时 140 毫秒
41.
Zheng Xiaoqing 《保鲜与加工》1995,(4):9-17
In view of the complication of compreliensive evaluation to development projectplanning alternatives,an AHP model for comprehensive evaluation to the alternatives is advanced,the way of determinating the weight of each index affecting the aIternatives' quality is expounded,and the general methods of evaluating the alternatives with the indexes are given. 相似文献
42.
The policy of public participation in urban planning was first practiced in Europe in the 1960s. After 40 years of development, the policy has become the essential step of city planning in Western countries where as is just at the elementary step in China. For the purpose of knowing the situation about the policy performing in local cities and discussing the feasibility of public participation in urban planning, several kinds of investigation have been done. From the investigation, it is found that although the public participation has already been the important step of urban planning in some city during just several years,there are still many problems. This paper shows a panorama view of this issue. Th describe the future of public participation in e authors will offer some solutions according to the problems and the urban planning. 相似文献
43.
Interest in DNA computing has increased overwhelmingly since Adleman successfully demonstrated its capability to solve Hamiltonian Path Problem. This article introduces the improving method in virtue of the biological thery of DNA technology, a new molecular algorithm is advanced. After a numerical simulation, the result shows that it avoids the prematurely and lower convergent speed of the classic genetic algorithm, and inherits global search capability, the validity and the speed of the genetic algorithm have been increased. The best result can be obtained in few iterative times. It is fit for solving path planning problem. 相似文献
44.
Zen Fanqi Gu Yuasheng Zen Xianglin 《保鲜与加工》1993,(4):136-143
Based on the network planning model developed by the author for an overhaul project of a rolling mill production line in a heavy steel plant, an new multiobjective network planning model is proposed in this paper. The formulations of network time parameters are derived. The optimization problem of multiobjective network planning is also discussed. And it has been found out that the fractional single-objctive network is only one of the cases in this model. 相似文献
45.
Sun Hongbo Xu Guoyu Qin Yihong 《保鲜与加工》1992,(4):80-86
This paper proposes a multi - objective fuzzy decision - making approach for power network planning under uncertainty ,which simutaneously considers not only the least investment cost,the minimum power loss,the maximum reliability,and the least environmental impacts, but also the uncertainty about the future load growth and the capital investment availability. The validity and effectiveness of the proposed approach is verified with numerical examples. 相似文献
46.
47.
基于Petri网的产品拆卸过程规划 总被引:1,自引:1,他引:1
引用拆卸优先矩阵来描述产品零件间的物理特性,并以优先矩阵为基础,以Petri网为工具,建立了包括零部件回收价值及拆卸成本在内的产品拆卸Petri网模型,采用Petri网基于不变量的性能分析方法,对模型进行求解,得到了满足需求约束的最佳拆卸序列。 相似文献
48.
This paper describes a role playing planning exercise that has been used for training agriculturists, engineers and agricultural economists for more than ten years. It sets out the objectives and key features of the exercise and the experience that has been gained in its use. The exercise has been found to successfully test and integrate subject matter expertise acquired from formal teaching. It also highlights the multiple and often conflicting objectives of irrigation planning, and the need for full evaluation of alternatives and sound technical judgements under conditions of inadequate data and time pressure. The exercise is also successful in developing professional personal skills such as group working, interviewing and presentation, and is recommended as an effective training aid. 相似文献
49.
本文提出了喷灌工程规划设计多方案选优的语言化与定量化相结合的模糊综合评判数学模型,从而可得到比传统喷灌工程规划设计方案选优方法更为合理、满意的结果。 相似文献
50.
基于GIS技术的小型水库规划方法 总被引:2,自引:2,他引:2
在小流域治理中,为了提高水库规划的精确度和速度,提出了基于GIS技术来实现小型水库规划的方法。主要是基于GIS技术的库客曲线的制作方法;小型水库规划的可视化。在GIS中,真实地形在计算机中的表达用数字高程模型(DEM)表示,水库规划的三维可视化环境的实现需利用0penGL技术。 相似文献