全文获取类型
收费全文 | 13085篇 |
免费 | 545篇 |
国内免费 | 1545篇 |
专业分类
林业 | 1456篇 |
农学 | 2128篇 |
基础科学 | 1403篇 |
2360篇 | |
综合类 | 3626篇 |
农作物 | 668篇 |
水产渔业 | 424篇 |
畜牧兽医 | 1790篇 |
园艺 | 370篇 |
植物保护 | 950篇 |
出版年
2024年 | 31篇 |
2023年 | 125篇 |
2022年 | 361篇 |
2021年 | 565篇 |
2020年 | 512篇 |
2019年 | 499篇 |
2018年 | 348篇 |
2017年 | 431篇 |
2016年 | 524篇 |
2015年 | 590篇 |
2014年 | 550篇 |
2013年 | 643篇 |
2012年 | 815篇 |
2011年 | 911篇 |
2010年 | 861篇 |
2009年 | 778篇 |
2008年 | 734篇 |
2007年 | 741篇 |
2006年 | 690篇 |
2005年 | 616篇 |
2004年 | 324篇 |
2003年 | 255篇 |
2002年 | 218篇 |
2001年 | 220篇 |
2000年 | 266篇 |
1999年 | 372篇 |
1998年 | 300篇 |
1997年 | 300篇 |
1996年 | 262篇 |
1995年 | 236篇 |
1994年 | 219篇 |
1993年 | 190篇 |
1992年 | 162篇 |
1991年 | 112篇 |
1990年 | 103篇 |
1989年 | 93篇 |
1988年 | 68篇 |
1987年 | 37篇 |
1986年 | 24篇 |
1985年 | 11篇 |
1984年 | 17篇 |
1983年 | 10篇 |
1982年 | 7篇 |
1981年 | 5篇 |
1980年 | 7篇 |
1979年 | 4篇 |
1978年 | 3篇 |
1965年 | 5篇 |
1964年 | 3篇 |
1941年 | 3篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
11.
游离甲醛和人造板释放甲醛 总被引:20,自引:1,他引:20
甲醛是室内空气污染源,它常与甲醛系统粘接连在一起,本文根据国内外资料评述人造板甲醛释放量,分析了脲醛树脂的水解和人造板释放甲醛的机理,还介绍了甲醛的毒害,各国政府的有关法规以各种降低甲醛释放量的方法。 相似文献
12.
2007年6月24日,我基地1头牧羊犬产下5头仔犬,仔犬健康良好.9月12日进行健康检查时,发现其中1头小犬(公,3月龄)双侧肘头部有明显的肿胀,触诊有温热感,波动明显,大如鸡蛋.小犬精神状态良好,体温、吃喝正常,未出现其他异常情况. 相似文献
13.
14.
15.
Yao Baoan Zhao Junlong Ma Lihua Liu Zhongling 《Tropical animal health and production》1997,29(4):40S-42S
Tropical Animal Health and Production - Packed erythrocytes infected withBabesia bovis were mixed with an equal volume of 16% dimethyl sulphoxide (DMS0) in Alsever’s solution and dispensed... 相似文献
16.
Michal Vla?ín Robert Luká? Zuzana Kauerová Pavel Kohout Josef Ma?ek Eli?ka Bartheldyová ?těpán Koudelka Zina Korvasová Jana Plocková Nikola Hronová Jaroslav Turánek 《Canadian journal of veterinary research》2014,78(2):133-139
Specific contrast ultrasound is widely applied in diagnostic procedures on humans but remains underused in veterinary medicine. The objective of this study was to evaluate the use of microbubble-based contrast for rapid ultrasonographic diagnosis of thrombosis in small animals, using male New Zealand white rabbits (average weight about 3.5 kg) as a model. It was hypothesized that the use of microbubble-based contrast agents will result in a faster and more precise diagnosis in our model of thrombosis. A pro-coagulant environment had been previously established by combining endothelial denudation and external vessel wall damage. Visualization of thrombi was achieved by application of contrast microbubbles [sterically stabilized, phospholipid-based microbubbles filled with sulfur hexafluoride (SF6) gas] and ultrasonography. As a result, rapid and clear diagnosis of thrombi in aorta abdominalis was achieved within 10 to 30 s (mean: 17.3 s) by applying microbubbles as an ultrasound contrast medium. In the control group, diagnosis was not possible or took 90 to 180 s. Therefore, sterically stabilized microbubbles were found to be a suitable contrast agent for the rapid diagnosis of thrombi in an experimental model in rabbits. This contrast agent could be of practical importance in small animal practice for rapid diagnosis of thrombosis. 相似文献
17.
18.
[Objective] The paper was to investigate effects on fermentation bed temperature,growth performance,diarrhea rate and digestive en-zyme activity of weaning piglets by using spent mushroom substrate of Pleurotus eryngii as padding.[Method] A total of 120 weaning piglets(Duroc × Landrace ×Yorkshire) with average initial body weight of(8.0 ±0.5)kg were allocated to five dietary treatments in a randomized complete block design for 42 d,each of which was replicated three times with eight piglets per replicate(half male,half female).The padding for control group was(50% sawdust +50% rice husk);experimental group Ⅰ 100% spent mushroom substrate;experimental group Ⅱ(15% sawdust +15% rice husk +70% spent mushroom substrate);experimental group Ⅲ(25% sawdust +25% rice husk +50% spent mushroom substrate);experimental group Ⅳ(35% sawdust +35% rice husk +30% spent substrate).[Result] There was no significant difference in surface temperature of fermentation bed between experimental groups and control group(P0.05).Compared with the control group,the temperature under 20 cm of fermentation bed in ex-perimental groups I,Ⅱ and Ⅲ increased significantly(P0.05).Except for experimental group Ⅳ,other three experimental groups had higher aver-age daily gain(P0.05) and experimental group Ⅰ had higher average daily feed intake(P0.05) compared to the control group.The diarrhea rate and mortality of weaning piglets in experimental groups Ⅱ,Ⅲ and Ⅳ were significantly decreased compared with the control group(P0.05).Compared with the control group,other three experimental groups had higher digestive enzyme activity in duodenal contents except for experimental group Ⅳ(P0.05).[Conclusion] Spent mushroom substrate of P.eryngii can be used as fermentation bed padding,and the optimal proportion was experimental group Ⅲ. 相似文献
19.
Zhang Q Li D Liu X Liu Z Cai X Wu G Qi S Yang S Yan X Shang Y He J Ma J Li J Ma W Han R Liu X Zhang J Xie Q Zhang Z 《Research in veterinary science》2008,85(2):368-371
This study was carried out to investigate the biological characteristics of the foot-and-mouth disease (FMD) virus strain Asia-1 China/2005, which is responsible for the 2005 epidemic in China. The result showed that this strain is not host restricted, and could not only cause FMD in cattle and sheep but also in pigs by either inoculation or direct contact. 相似文献
20.
粤北桑芽瘿蚊Giadomyiasp是粤北桑树的主要害虫之一,其形态特征主要表现在成虫触角、前翅、外生殖器的形态,卵、幼虫胸骨片的形状,蛹胸足长短等方面,与广东老蚕区(顺德)的桑吸浆虫(Contariniasp.)有着明显差异。 相似文献