全文获取类型
收费全文 | 9476篇 |
免费 | 498篇 |
国内免费 | 759篇 |
专业分类
林业 | 1330篇 |
农学 | 611篇 |
基础科学 | 2191篇 |
1355篇 | |
综合类 | 3303篇 |
农作物 | 170篇 |
水产渔业 | 644篇 |
畜牧兽医 | 493篇 |
园艺 | 133篇 |
植物保护 | 503篇 |
出版年
2024年 | 65篇 |
2023年 | 185篇 |
2022年 | 245篇 |
2021年 | 262篇 |
2020年 | 315篇 |
2019年 | 346篇 |
2018年 | 199篇 |
2017年 | 286篇 |
2016年 | 336篇 |
2015年 | 299篇 |
2014年 | 444篇 |
2013年 | 428篇 |
2012年 | 661篇 |
2011年 | 588篇 |
2010年 | 477篇 |
2009年 | 542篇 |
2008年 | 523篇 |
2007年 | 977篇 |
2006年 | 788篇 |
2005年 | 603篇 |
2004年 | 543篇 |
2003年 | 443篇 |
2002年 | 219篇 |
2001年 | 184篇 |
2000年 | 151篇 |
1999年 | 121篇 |
1998年 | 68篇 |
1997年 | 69篇 |
1996年 | 55篇 |
1995年 | 61篇 |
1994年 | 50篇 |
1993年 | 38篇 |
1992年 | 29篇 |
1991年 | 39篇 |
1990年 | 26篇 |
1989年 | 18篇 |
1988年 | 17篇 |
1987年 | 7篇 |
1986年 | 6篇 |
1984年 | 3篇 |
1982年 | 4篇 |
1981年 | 1篇 |
1980年 | 2篇 |
1979年 | 1篇 |
1978年 | 2篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1955年 | 5篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
农业机械化是农业现代化的基础,是现代化的先决条件,发展农业机械化迫切需要加大投入。为此,分析了金华市现阶段农机化投入的现状及存在的问题;提出了通过建立政府、集体、信贷、农户、外资等“多位一体”的投入机制,加大农机化投入,促进农机化事业健康发展的思路。 相似文献
2.
从师生自身反馈角度,结合成立于2003年的中国地质大学工程学院土木工程试验班的具体情况,针对其本硕贯通式的培养教学计划,提出了包括增加专业软件学习、互动式外语教学、高低阶力学课程合并、压缩人文社科类课程等具体改进建议。 相似文献
3.
本文论述了在工程建设中钢筋混凝土质量优劣的重要性,并结合当前施工中存在的一些问题,探讨了该采取的方法,以达到控制工程质量的目的。 相似文献
4.
抓好公路施工管理与质量管理的体会 总被引:3,自引:0,他引:3
工程质量是企业素质的综合反映,是项目管理水平的重要标志。质量是企业的生命线。 相似文献
5.
液压技术的应用已成为现代化农业机械的典型标志。为此,介绍了农机液压技术的应用现状;并根据科学技术的发展,简要分析了农机液压技术的发展趋势。 相似文献
6.
7.
P. Laffaille A. Acou J. Guillouët B. Mounaix A. Legault 《Ecology of Freshwater Fish》2006,15(4):583-588
Abstract – Changes in the numbers and size-class structure of European silver eels, Anguilla anguilla , in the River Frémur (France) were examined over a 9-year period after installation of downstream eel passes. The number of silver eels migrating downstream peaked in 1999, then decreased strongly and steadily after 2000, reaching relatively low levels. At the same time, a gradual shift in the silver eel sex ratio from a dominance of males (size from 270 to 442 mm, age from 3 to 6 years) to females (size from 366 to 1112 mm, age from 4 to 9 years) was recorded. Possible explanations for the escapement patterns observed are environmental sex determination and the installation of eel passes on the main hydraulic engineering structures in 1992 and 1996. 相似文献
8.
Articular cartilage repair is one of the most challenging issues which remains to be resolved in clinic work. Discovering of bone marrow stromal cells (BMSC) and its application in tissue engineering provide new methods for the treatment of cartilage defects. High seeding density, appropriate cytokines and three-dimensional culture play important roles in the process of inducing BMSC differentiating into chondrocytes, suitable scaffold is also essential in reconstructing cartilage in vitro by methods of tissue engineering. 相似文献
9.
Effects of straw and silicon soil amendments on some foliar and stem-base diseases in pot-grown winter wheat 总被引:2,自引:0,他引:2
Four foliar and two stem-base pathogens were inoculated onto wheat plants grown in different substrates in pot experiments. Soils from four different UK locations were each treated in three ways: (i) straw incorporated in the field at 10 t ha−1 several months previously; (ii) silicon fertilization at 100 mg L−1 during the experiment; and (iii) no amendments. A sand and vermiculite mix was used with and without silicon amendment. The silicon treatment increased plant silica concentrations in all experiments, but incorporating straw was not associated with raised plant silica concentrations. Blumeria graminis and Puccinia recondita were inoculated by shaking infected plants over the test plants, followed by suitable humid periods. The silicon treatment reduced powdery mildew ( B. graminis ) substantially in sand and vermiculite and in two of the soils, but there were no effects on the slight infection by brown rust ( P. recondita ). Phaeosphaeria nodorum and Mycosphaerella graminicola were inoculated as conidial suspensions. Leaf spot caused by P. nodorum was reduced in silicon-amended sand and vermiculite; soil was not tested. Symptoms of septoria leaf blotch caused by M. graminicola were reduced by silicon amendment in a severely infected sand and vermiculite experiment but not in soil or a slightly infected sand and vermiculite experiment. Oculimacula yallundae (eyespot) and Fusarium culmorum (brown foot rot) were inoculated as agar plugs on the stem base. Severity of O. yallundae was reduced by silicon amendment of two of the soils but not sand and vermiculite; brown foot rot symptoms caused by F. culmorum were unaffected by silicon amendment. The straw treatment reduced severity of powdery mildew but did not detectably affect the other pathogens. Both straw and silicon treatments appeared to increase plant resistance to all diseases only under high disease pressure. 相似文献
10.
浅谈工程造价的预结算审核 总被引:2,自引:0,他引:2
工程造价的预结算审核是合理确定工程造价的必要程序及重要手段.本文从工程造价中存在的问题,工程造价审核的内容、方法等三个方面论述了工程造价及其预结算的审核工作过程. 相似文献