全文获取类型
收费全文 | 734篇 |
免费 | 26篇 |
国内免费 | 9篇 |
专业分类
林业 | 33篇 |
农学 | 217篇 |
基础科学 | 51篇 |
71篇 | |
综合类 | 219篇 |
农作物 | 42篇 |
水产渔业 | 9篇 |
畜牧兽医 | 73篇 |
园艺 | 22篇 |
植物保护 | 32篇 |
出版年
2024年 | 12篇 |
2023年 | 35篇 |
2022年 | 44篇 |
2021年 | 25篇 |
2020年 | 15篇 |
2019年 | 25篇 |
2018年 | 14篇 |
2017年 | 17篇 |
2016年 | 19篇 |
2015年 | 15篇 |
2014年 | 35篇 |
2013年 | 40篇 |
2012年 | 45篇 |
2011年 | 49篇 |
2010年 | 37篇 |
2009年 | 37篇 |
2008年 | 41篇 |
2007年 | 30篇 |
2006年 | 47篇 |
2005年 | 24篇 |
2004年 | 14篇 |
2003年 | 24篇 |
2002年 | 20篇 |
2001年 | 19篇 |
2000年 | 11篇 |
1999年 | 5篇 |
1998年 | 5篇 |
1997年 | 5篇 |
1996年 | 2篇 |
1995年 | 7篇 |
1994年 | 7篇 |
1993年 | 2篇 |
1992年 | 8篇 |
1991年 | 5篇 |
1990年 | 4篇 |
1989年 | 8篇 |
1988年 | 5篇 |
1987年 | 4篇 |
1986年 | 5篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1958年 | 1篇 |
排序方式: 共有769条查询结果,搜索用时 15 毫秒
1.
肉鹅的骨骼在2—6周龄,肌肉在4.9周龄生长发育最快。根据这一生长发育规律,对肉鹅进行大棚快速育肥,可获得理想的经济效益。 相似文献
2.
Ning De-juan Hou Pei-chen Hu Zan-min Shen Xin Chen Shao-liang College of Biological Sciences Biotechnology Beijing Forestry University Beijing P. R. China Institute of Genetics Developmental Biology Chinese Academy of Sciences Beijing P. R. China 《中国林学(英文版)》2006,8(4):15-19
For this paper, the plasma membrane (PM) H -ATPase gene has been cloned from Populus euphratica Oliv. through a homology based strategy. The isolated 3,210 bp cDNA contains a single 2,862 bp open reading frame (ORF) which encodes a putative H -ATPase protein of 953 amino acid residues, with a significant homology to plasma membrane H -ATPase of Primus persica, Phaseolus vulgaris, Sesbania rostrata and Daucus carota. The predicted protein has a molecular weight of 104,553 Da. The copy number analysis revealed multiple copies of the PM H -ATPase in the P. euphratica genome after digestion of their genomic DNA by the restriction enzymes EcoRI, NdeⅠ, FbaⅠand BglⅡ, and Southern blot. 相似文献
3.
越冬橘园蜘蛛群落多样性研究 总被引:2,自引:0,他引:2
通过系统调查,湖南省邵阳市越冬橘园蜘蛛群落共有12科22属28种,其中斑管巢蛛(Clubionareichlini)和美丽蚁蛛(Myrmarachaefarmicaria)为优势种。异质性大的越冬橘园蜘蛛群落的多样性指数、丰富度和个体总数均大于异质性小的越冬橘园,越冬橘园蜘蛛群落的多样性指数大小主要由群落物种丰富度和个体总数决定,与均匀度大小无关。 相似文献
4.
余庆位于黔中腹地,拥有良好的茶叶生长环境生长,但茶叶经济蒸蒸日上的同时,茶园基础管理也出现了茶园老化低产、管理不当、茶园的基础环境差等问题。对此可以通过更新茶树、改造树冠、土壤、园相,加强生态建设并辅以改造后的管理等方法改善上述问题。 相似文献
5.
本文根据灌溉配水渠系的运行特点,提出在一定轮期和来水流量限制条件下实现下级配水渠最优组合及其配水时间最优排序的一种0-1规划模型,实例运算表明,这种方法可有效减少无效弃水和闸门调节次数,同时对渠道横断面的设计有参考意义。 相似文献
6.
Based on the theory of the K map simplification of logical function(KSLF),this article releases a ICAI Realization for KSLF.Providing three kinds of teaching style:commonness, teaching, practice.This product,wich supports for the K map simplification with random item,is not only helpful to the construction of the curriculum of digital circuit ,but also to the design for digital application system.Under the practice method, This product's guides,checks,and corrects the student's whole process forthe proceeding of KSLF automaticly under the teaching method. 相似文献
7.
Du Yang Xin Mingdao Huang Shaoming 《保鲜与加工》1995,(5):50-56
A new type of three dimenstional inner microfin tube is devoloped. Under four different pressures and in the range of condensing mass velocities from 33 to 153 kg/m2 . s,and by the experimental study of the three kinds of tubes with different microfin parameters, the performances of the condensation heat transfer for R11 in the horizontal microfin tubes and obtained. The experiments show that the inner microfin tube is a hopeful and nighty effective condensing heat transfer enhancement tube. 相似文献
8.
In urban design, only by continuous and dynamic research work from design to finally putting it into practice, can we made good control on city appearance. This article analyzes nowadays defects in our urban design from two aspects as the result establishment and validated control, and tries to conceive a feasibility plan to solve the problem. 相似文献
9.
10.
According to the requirements of communication power supply, such as high reliability, wide application and high availability, the authors raise a new remote control design for a multi-output power supply for communication equipment based on TCPIP protocol and embedded technology. Then the hardware design is given for the system is discussed based on Ethernet professional chip PRTL8019AS and related circuits. The firmware software design for the salve-computer based TCPIP technology, and the soft design of communieation and control for the master-computer are proposed based on Winsoek and MFC technology in detail A test machine is built to do the testing, the test results prove that the test machine works stably and well, satisfies the design rules and also provides a feasible method for the remote supervise in communication power supplier whose requirement includes remote supervise, no-people on duty and so on. 相似文献