全文获取类型
收费全文 | 12315篇 |
免费 | 3717篇 |
专业分类
林业 | 1606篇 |
农学 | 580篇 |
基础科学 | 10篇 |
2480篇 | |
综合类 | 580篇 |
农作物 | 234篇 |
水产渔业 | 2662篇 |
畜牧兽医 | 6076篇 |
园艺 | 141篇 |
植物保护 | 1663篇 |
出版年
2023年 | 35篇 |
2022年 | 48篇 |
2021年 | 208篇 |
2020年 | 545篇 |
2019年 | 1060篇 |
2018年 | 1057篇 |
2017年 | 1091篇 |
2016年 | 1070篇 |
2015年 | 932篇 |
2014年 | 942篇 |
2013年 | 1300篇 |
2012年 | 772篇 |
2011年 | 813篇 |
2010年 | 752篇 |
2009年 | 391篇 |
2008年 | 514篇 |
2007年 | 391篇 |
2006年 | 422篇 |
2005年 | 357篇 |
2004年 | 362篇 |
2003年 | 372篇 |
2002年 | 329篇 |
2001年 | 251篇 |
2000年 | 272篇 |
1999年 | 111篇 |
1998年 | 38篇 |
1997年 | 48篇 |
1996年 | 49篇 |
1995年 | 81篇 |
1994年 | 48篇 |
1993年 | 30篇 |
1992年 | 26篇 |
1990年 | 27篇 |
1988年 | 26篇 |
1986年 | 33篇 |
1985年 | 28篇 |
1984年 | 26篇 |
1983年 | 24篇 |
1980年 | 29篇 |
1977年 | 27篇 |
1948年 | 33篇 |
1942年 | 53篇 |
1941年 | 46篇 |
1940年 | 44篇 |
1939年 | 51篇 |
1938年 | 34篇 |
1937年 | 31篇 |
1936年 | 23篇 |
1935年 | 47篇 |
1931年 | 24篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Compatibility of root growth and tuber production of potato cultivars with dynamic and static water‐saving irrigation managements
下载免费PDF全文
![点击此处可从《Soil Use and Management》网站下载免费的PDF全文](/ch/ext_images/free.gif)
S. H. Ahmadi M. Agharezaee A. A. Kamgar‐Haghighi A. R. Sepaskhah 《Soil Use and Management》2017,33(1):106-119
The important root characteristics of root length density (RLD) and root mass density (RMD) generally differ among irrigation managements and potato cultivars. The objective of this study was to investigate the RLD and RMD variations and their functional relationships with gross potato tuber yield for two commercial potato cultivars, Agria and Sante, under different irrigation strategies. Full irrigation and water‐saving irrigation strategies, deficit and partial root drying irrigations, were applied statically (S) and dynamically (D) based on daily crop evapotranspiration. Results showed that SPRD had significantly greater RLD (3.64 cm/cm3) and RMD (132.7 μg/cm3) than other irrigation treatments. Between the potato cultivars, Agria had significantly larger values of RLD (3.50 cm/cm3) and RMD (138.7 μg/cm3) than Sante. The functional relationship between the root growth characteristics and tuber yield showed that under water‐saving irrigations, Agria increased root mass at the expense of gross tuber yield but Sante increased root mass to maintain larger gross tuber yields. However, Agria produced more roots and gross tuber yield than Sante, and it is concluded that Agria is a more drought‐tolerant potato cultivar, which is recommended for tuber production in regions where water might be scarce. It was shown that larger root production in potatoes was associated with improved tolerance to water stress. 相似文献
2.
T. Pudert A. Weyrich F. Geburek C. Herden M. Röcken 《Equine Veterinary Education》2021,33(11):e386-e392
Thymoma is a rare condition in horses. This case of a 24-year-old Warmblood gelding that was presented with oedema and signs of vascular congestion of the left forelimb caused by a thoracic mass is described. The diagnostic work-up included blood chemistry, cytology of pleural effusion, ultrasonography, radiography and the visualisation and collection of a tissue sample by thoracoscopy. Finally, post-mortem findings and histopathology revealed thymic epithelial neoplasia with histomorphologic features previously unreported in horses. The unique mixture of spindle-shaped and epithelioid tumour cells in combination with clear features of malignancy suggested the application of the Moran and Suster histological classification system for thymomas in humans (Moran and Suster, 2008, Curr. Treat. Options Oncol., 9, 288), which has not been reported in an equine case before and fits well to the present case. 相似文献
3.
Kim Birnie‐Gauvin Lasse Birch Hjrup Theis Kragh Lene Jacobsen Kim Aarestrup 《Ecology of Freshwater Fish》2019,28(3):376-384
Pike (Esox lucius) occupy coastal streams and rivers of the Baltic Sea, where they attain large sizes (>5 kg). These large sizes are perhaps due to the fact that they can tolerate relatively high salinities and can thus forage in the nearby more productive brackish environments. In an attempt to quantify the extent to which pike utilise brackish environments, and to provide some insight into the underlying causes for brackish water migrations, we tagged 30 pike from a western Baltic river with acoustic transmitters and were able to track 21 individuals for 1 year. Based on experienced from local anglers, this population was assumed to be brackish in nature, where individuals underwent freshwater migrations to spawn. Our findings however suggest that the smallest and most active individuals make short exits into brackish waters and do so on rare occasions. Our results further indicate that neither sex nor size is related to activity level. We suggest that these patterns reflect two distinct behaviours—active and passive—and that large pike can be supported by the food availability in the river, without the need to venture into coastal zones, thus defying the conventional view that Baltic pike are all brackish in nature. 相似文献
4.
5.
B. Götz 《Journal of pest science》1938,14(8):92-93
Ohne Zusammenfassung 相似文献
6.
7.
Fr. 《Journal of pest science》1942,18(11):131
Ohne Zusammenfassung 相似文献
8.
9.
10.
Revierförfter von Mühlen zu Solitude 《European Journal of Forest Research》1868,12(1):340-342
Ohne Zusammenfassung
Bergleiche Auguftheft diefer Bl?tter, in melchem gleichfalls auf die Wichtigfeit diefes Qegenftandes hingemiefen murde. Die
Red. 相似文献