全文获取类型
| 收费全文 | 304篇 |
| 免费 | 19篇 |
| 国内免费 | 78篇 |
专业分类
| 林业 | 32篇 |
| 农学 | 42篇 |
| 基础科学 | 7篇 |
| 25篇 | |
| 综合类 | 128篇 |
| 农作物 | 37篇 |
| 水产渔业 | 30篇 |
| 畜牧兽医 | 89篇 |
| 植物保护 | 11篇 |
出版年
| 2024年 | 1篇 |
| 2022年 | 1篇 |
| 2021年 | 3篇 |
| 2020年 | 4篇 |
| 2019年 | 3篇 |
| 2018年 | 1篇 |
| 2017年 | 1篇 |
| 2016年 | 3篇 |
| 2014年 | 4篇 |
| 2013年 | 18篇 |
| 2012年 | 18篇 |
| 2011年 | 24篇 |
| 2010年 | 22篇 |
| 2009年 | 8篇 |
| 2008年 | 10篇 |
| 2007年 | 3篇 |
| 2006年 | 7篇 |
| 2005年 | 9篇 |
| 2004年 | 20篇 |
| 2003年 | 41篇 |
| 2002年 | 61篇 |
| 2001年 | 60篇 |
| 2000年 | 42篇 |
| 1999年 | 24篇 |
| 1997年 | 5篇 |
| 1995年 | 2篇 |
| 1994年 | 2篇 |
| 1993年 | 1篇 |
| 1992年 | 1篇 |
| 1991年 | 1篇 |
| 1988年 | 1篇 |
排序方式： 共有401条查询结果，搜索用时 453 毫秒
31.
32.
33.
The composite material of nano-Al 2O 3 and UHMW-PE was made by the way of pressing and agglomeration. Effect of nano-Al 2O 3 on the friction, wear characteristic of Ultra High Molecular Weight Polyethylene plastic was studied by using MPV-200 model friction and wear tester and caustic wear one. At the same time, the hardness of UHMW-PE was mensurated in sclerometer. The results showed that nano-Al 2O 3 not only decreases the friction coefficient of UHMW-PE, but also greatly reduce the wear of UHMW-PE.The hardness of UHMW-PE is improved. Which possesses important theoretic significance for optimizing of structure and property of UHMW-PE material. 相似文献
34.
35.
In Chinese traditional medicine, the pulse signal plays an important role for diagnosis. To investigate the effective technique for identifying heroin druggers through the pulse signal, the feature extraction algorithm based on the biocepstrum and the third-order cepstrum entropy of the pulse signal is studied. On the basis of concise and rigorous discussion for the algorithm, the biocepstrum-based diagonal slice components are estimated for human pulse signals of 20 heroin druggers and 20 healthy normal subjects. The magnitude of the sample value of diagonal slice at m=n=1 and the third-order cepstrum entropy of magnitudes of sample values of the diagonal slice within a particular region are used as two feature parameters for every human pulse signal to form a feature vector. A classifier based on the criterion of squared Mahalanobis distance is successfully designed. Applying the designed classifier to 40 feature vectors, the correct identification rate reaches 87.5%. The research result shows that the method of the feature extraction and classifier design presented in is valuable for identifying the human pulse signals of heroin druggers. 相似文献
36.
In view of the necessity of gas detection in environment, an embedded gas detection system is designed based on the basic principles of chromatography change of chemical reaction between nano-porphyrin arrays and micro-gas, which takes ARM9 S3C2440A as the core and nano-porphyrin array as the sensors. The overall program, the circuit organization and control software of the main function module such as spectrum signal acquisition, processing and monitoring are presented. With energy conservation differential equation, the control model of temperature and flow rate in the sample chamber is established, which can precisely control the detection conditions of chemical sensors. Some typical trace gases such as ammonia, enanthaldehyde, cyclohexane and hexanal are tested by the system, and the results show that the system can achieve rapid and accurate detection of trace volatile gas. 相似文献
37.
Job shop scheduling is an important part of manufacturing process. Pre-mature, local optimal solution or low convergence rate of Genetic Algorithm may come across in solving scheduling problem in multi-Job shop. To avoid those unhealthy tendencies, this paper introduced the Dynamical Niche Sets-based Cooperative Evolutionary Algorithm model.In the Algorithm, Process-based chromosome encoding method was used; the crossover operator and mutation operator were designed to adjust operation sequences and choose process routes. The cooperative scheduling problem in multi-Job shop was solved using dynamical niche sets technology and multi-population cooperative evolution method. The Experiment result shows the proposed method has good advantages. 相似文献
38.
采取适当的栽培设施 ,通过调节温、光等环境因子 ,以料代土 ,研究寒冷季节草皮的工厂化生产技术 ,以改变传统的种植方式 相似文献
39.
采用回归通用旋转设计方法试验,组建了以水稻纹枯病进展速率(R)为目标函数的数学模型:结果表明:对纹枯病进展速率的影响是氮量>密度>钾肥,其中以施氮量为关键因素;对病害进展速率影响的交互因素是氮量和钾肥。经模型的模拟优化和仿真,在试验幅度内,每亩施纯氮量最高,钾肥用量最小,密度最大的情况下,病害进展速率最大;在施氮量最小、钾肥量偏低、密度最小的情况下,病害进展速率最小(最优)。 相似文献
40.
软枣猕猴桃原生质体培养与细胞团再生的初步研究 总被引：7，自引：1，他引：7
以软猕猴桃叶片、叶片愈伤组织为材料，研究了影响原生质体分离和培养的因素。结果表明，原生质体分离，酶液配方2优于配方1，成龄叶片优于幼龄叶片；培养方法以浅层培养法最好；改良MS液体培养基培养愈伤组织原生质体，5-7d出现第一次细胞分裂，14d出现第2次细胞分裂，30d形成多细胞团，55d形成肉眼可见的小愈伤组织。 相似文献