全文获取类型
收费全文 | 662篇 |
免费 | 5篇 |
国内免费 | 1篇 |
专业分类
林业 | 25篇 |
农学 | 417篇 |
基础科学 | 1篇 |
51篇 | |
综合类 | 55篇 |
农作物 | 23篇 |
水产渔业 | 4篇 |
畜牧兽医 | 70篇 |
园艺 | 1篇 |
植物保护 | 21篇 |
出版年
2024年 | 5篇 |
2023年 | 14篇 |
2022年 | 16篇 |
2021年 | 8篇 |
2020年 | 3篇 |
2019年 | 4篇 |
2018年 | 2篇 |
2016年 | 4篇 |
2015年 | 3篇 |
2014年 | 7篇 |
2013年 | 11篇 |
2012年 | 53篇 |
2011年 | 62篇 |
2010年 | 51篇 |
2009年 | 62篇 |
2008年 | 64篇 |
2007年 | 17篇 |
2006年 | 27篇 |
2005年 | 19篇 |
2004年 | 12篇 |
2003年 | 36篇 |
2002年 | 62篇 |
2001年 | 29篇 |
2000年 | 34篇 |
1999年 | 7篇 |
1998年 | 5篇 |
1997年 | 6篇 |
1996年 | 7篇 |
1995年 | 6篇 |
1994年 | 6篇 |
1993年 | 3篇 |
1992年 | 6篇 |
1991年 | 3篇 |
1990年 | 7篇 |
1989年 | 1篇 |
1988年 | 3篇 |
1983年 | 2篇 |
1981年 | 1篇 |
排序方式: 共有668条查询结果,搜索用时 609 毫秒
41.
Based on the relationship between cities and inhabitants as the main point, the characters, complexity and openness of the urban system are discussed in this paper. Then, the nature of the city is revealed. 相似文献
42.
In the elastic-plastic solution of expansion of cylinder cavities based on Tresca strength criterion and Mohr-Coulomb strength criterion, the influence of neutral principal stress is not considered. In this paper the influence of neutral principal stress on elastic-plastic solution of expansion of cylinder cavities is considered. The calculation shows that the radius and displacement of plastic zone will reduce when the neutral principal stress is considered. The conclusions are of practical significance for geotechnical engineering. 相似文献
43.
Research on Main Microorganism Groups and Their Ecological Law im Aeration Sludge Composting Process
This paper emphatically probes into main microorganism groups and their characteristics in sewage sludge aeration composition system,and relationships between these groups and the environmental factors.Researches show that there exist interactions between microorganism groups and the environmental factors,such as organic matters,temperature and pH.Organic matters and temperature are two primary factors that effect on variations of microorganism groups. pH is a non-primary environmental factor.It is also found that microbial quantity variation curve in sludge composting process is different from that of in wastewater treatment process. 相似文献
44.
Xiao Weipin 《保鲜与加工》1996,(1):37-46
This paper discusses an important part of"The Decision Support System of Science Technology Management in Building Enterprises". It established the synthetical target system of business plan in the building enterprises, business effect prediction models, business plan decision models and their algorithm, business plan target system etc. 相似文献
45.
Xiao Dichen Liang Xichang 《保鲜与加工》1990,(1):13-22
In this paper, a calculation method of forming cutter contour of involute helical with arbitrary easement is presented, the segmantal arcs of the best uniform approximation and tolerance to fit smoothly the cutter contour points are used the profile on the cross section of the helical is calculated and the design of the cutter is examined. The method can be used to design precision forming cutter of involute helical with the arbitrary easement. It is valuable in engineering application. 相似文献
46.
A brief review on the origin of V-notched blasting and its application in engineering is given. A study on the fracturing mechanism and stress intensity factor at the tip of V-notch and parameter of the V-notched rock blasting is introduced based on reference given in this paper. It represents an idea of spiral V-notched blasting at last. 相似文献
47.
Product design now has a significant influence on the profitability of a business. Enterprise simulation can not only overcome the limitations of current product scheme cost evaluation methods , but also support Product Scheme Cost design of Dynamic Enterprise. Product Scheme Cost Design basing on Value Innovation Method aim at value increase , and use Enterprise simulation as Product design tools. To evaluate different design options, a series of runs are performed in Enterprise simulation system for each design variant. In this way , Product design face on enterprise business. This paper focus on value chain,and use it in Product design, provide a new way for Product design of Dynamic Enterprise. 相似文献
48.
Analysis on Unbalance of Real Estate Investment Goal under the Environment of High Profit Margin
下载免费PDF全文
![点击此处可从《保鲜与加工》网站下载免费的PDF全文](/ch/ext_images/free.gif)
With incessant development of Chinese real estate market, the amount and size of real estate corporations are enlarging rapidly and the real estate corporation investment goal is tending to become divertive. So it is especially important to understand rightly the investment goal of the real estate corporations. This paper analyzes the unbalance phenomena of real estate corporation investment under the environment of high profit margin and discusses the serious aftereffect from this unbalance. Finally this paper brings forward the right order of investment goals for the real estate corporations in order to contribute to a nicer performance of real estate corporations in establishing sustainable development stratagem. 相似文献
49.
The Sijiaotian Tunnel in Yunnan Dabao Highway lies in the narrow defile landscape,and the engineering geology condition is complex,with plenty of cienega.According to the actual situation of the Sijiaotian Tunnel Project in Yunnan Dabao Highway,the stability of the surrounding rock mass is studied by using a 3-D non-linear FEM.The Drucker-Prager criterion is chosen as the failure criterion of the rock.The relatively dangerous zone and the monitoring points in the tunnel are determined.The numerical results show that the Sijiaotian Tunnel is relatively stable.The conclusion has some significance for guiding the construction of similar projects. 相似文献
50.
on the basis of the experimental studies of mechanical properties in brittle rock,the generalized elastic modulus,generalized elastic Poisson ratio,irreversible deformation Poisson ratio and damage deformation characteristic arediscussed.And then,a new damage variable is defined.A new nonlinear elastic-damage constitutive equation is built and the damage evolution equation is proposed.The nonlinear elastic-damage constitutive equation is verified in the uniaxialcompression test of quartz sandstone in Chongqing.The results show that reasonableagreement exists between the theoretical analysis and the experimental data. 相似文献