全文获取类型
收费全文 | 8874篇 |
免费 | 567篇 |
国内免费 | 51篇 |
专业分类
林业 | 550篇 |
农学 | 447篇 |
基础科学 | 80篇 |
1544篇 | |
综合类 | 634篇 |
农作物 | 450篇 |
水产渔业 | 683篇 |
畜牧兽医 | 4113篇 |
园艺 | 127篇 |
植物保护 | 864篇 |
出版年
2023年 | 82篇 |
2022年 | 155篇 |
2021年 | 279篇 |
2020年 | 273篇 |
2019年 | 339篇 |
2018年 | 292篇 |
2017年 | 321篇 |
2016年 | 331篇 |
2015年 | 234篇 |
2014年 | 319篇 |
2013年 | 497篇 |
2012年 | 518篇 |
2011年 | 558篇 |
2010年 | 275篇 |
2009年 | 315篇 |
2008年 | 438篇 |
2007年 | 437篇 |
2006年 | 388篇 |
2005年 | 366篇 |
2004年 | 333篇 |
2003年 | 304篇 |
2002年 | 344篇 |
2001年 | 241篇 |
2000年 | 244篇 |
1999年 | 204篇 |
1998年 | 59篇 |
1997年 | 59篇 |
1996年 | 55篇 |
1995年 | 51篇 |
1994年 | 38篇 |
1993年 | 38篇 |
1992年 | 80篇 |
1991年 | 52篇 |
1990年 | 61篇 |
1989年 | 66篇 |
1988年 | 62篇 |
1987年 | 51篇 |
1986年 | 46篇 |
1985年 | 60篇 |
1984年 | 39篇 |
1983年 | 42篇 |
1982年 | 31篇 |
1980年 | 23篇 |
1979年 | 37篇 |
1978年 | 21篇 |
1977年 | 21篇 |
1974年 | 23篇 |
1973年 | 25篇 |
1972年 | 24篇 |
1970年 | 26篇 |
排序方式: 共有9492条查询结果,搜索用时 0 毫秒
961.
962.
963.
van Wuijckhuise L Dercksen D Muskens J de Bruijn J Scheepers M Vrouenraets R 《Tijdschrift voor diergeneeskunde》2006,131(18):649-654
For the first time Bluetongue (BT) has been diagnosed in the Netherlands. The clinical symptoms of BT on five farms during the first outbreak ever in the Netherlands are described. Fever and swollen sensitive coronets leading to reluctance to stand and walk were sometimes the first symptoms. Later lesions in the mouth occurred with foamy salivation and respiratory problems. In other cases a swollen head with swollen lips and foamy salivation were the first clinical signs. Also sudden death occurred. In the first sixteen confirmed cases morbidity and mortality were lower than described in outbreaks in other countries. Good collaboration between practitioners, specialists of the Animal Health Service (GD-Deventer), and specialists of the Food and Consumer Product Safety Authority (VWA) and CIDC-Lelystad (Wageningen UR) led to a rapid notification and ultimately confirmation of the suspected diagnosis BT. 相似文献
964.
Prolonged elevated atmospheric CO2 might alter decomposition. In a 90-day incubation study, we determined the long-term (9 years) impact of elevated CO2 on N mineralization of Lolium perenne and Trifolium repens plant material grown at ambient and elevated CO2 and low- and high-15N fertilizer additions. No significant differences were observed in recovery rates between any of the treatments, except an N addition effect was observed for L. perenne (0.4 versus 0.5% day−1 in high versus low N). The results suggest that elevated CO2 did not change plant N mineralization in any of the soils, because of a surplus of available N in the fertilized and leguminous systems, and because of insignificant plant responses to elevated CO2 in the low soil N availability systems. 相似文献
965.
de Bruijckere G 《Tijdschrift voor diergeneeskunde》2006,131(8):300; author reply 300
966.
967.
968.
OBJECTIVE: To review the gross, microscopic, and functional anatomy of the cranial cruciate ligament (CCL) in dogs. STUDY DESIGN: Literature review. METHODS: Reports of the anatomy and function of the cruciate ligaments in dogs were retrieved by search of the 1975-2005 PubMed database. RESULTS: The CCL has an important biomechanical function resisting cranial drawer, hyperextension, and internal rotation and acts to fine tune and guide the stifle through its rolling and sliding motion. It has a complex architecture, and distinct geographic regions within the ligament have different functional roles depending on the angle and loading conditions. Collagen type I is the main component of the extracellular matrix; the fibrils have a crimped structure. The cruciate ligaments are almost completely covered by synovium, protecting them from synovial fluid. Cruciate blood supply is mainly of soft tissue origin. The intraligamentous network is relatively limited whereas the core of the middle third of the CCL is even less well vascularized. Neurohistologic studies are very limited in the dog. Various mechanoreceptors and proprioceptive receptors have been identified within the substance of the cruciate ligaments. CONCLUSIONS: CCL structural characteristics play an important part in its complex behaviour with the crimped pattern of the collagen fibrils being an important determinant of its biomechanical properties. In contrast to reports of managing CCL rupture, there are few reports describing the microanatomy and neurovascular morphology of the cruciate ligaments. CLINICAL RELEVANCE: Cruciate disease is likely multi-factorial. Improved understanding of CCL degradation leading to CCL rupture is critical to development of new diagnostic tests for cruciate disease in dogs. Appropriate intervention during the early stages of disease process might preserve CCL structural properties by preventing further collagen degradation. Accurate knowledge of functional and fiber bundle anatomy is imperative for reconstruction and restoration of normal stifle joint physiology. Reconstructive goals should alleviate existing instability and mimic normal kinematics. Knowledge of the exact function of the CCL in the neuromuscular control around the stifle joint could possibly explain osteoarthritis progression after CCL damage. 相似文献
969.
Bonnefont-Rebeix C de Carvalho CM Bernaud J Chabanne L Marchal T Rigal D 《Veterinary immunology and immunopathology》2006,109(1-2):167-176
In this study, canine monocyte-derived dendritic cells (cMo-DC) were produced in presence of canine GM-CSF (cGM-CSF) and canine IL-4 (cIL-4), and they were characterized by their dendritic morphology, MLR functionality and phenotype. We noticed that cMo-DC were labelled with three anti-human CD86 (FUN-1, BU63 and IT2.2 clones), whereas resting and activated lymphocytes or monocytes were not stained. CD86 expression was induced by cIL-4 and was up-regulated during the differentiation of the cMo-DC, with a maximum at day 7. Furthermore, cMo-DC were very potent even in low numbers as stimulator cells in allogeneic MLR, and BU63 mAb was able to completely block the cMo-DC-induced proliferation in MLR. We also observed that cMo-DC highly expressed MHC Class II and CD32, but we failed to determine their maturation state since the lack of commercially available canine markers. Moreover, cMo-DC contained cytoplasmic periodic microstructures, potentially new ultrastructural markers of canine DC recently described. In conclusion, this work demonstrates that the CD86 costimulatory marker is now usable for a better characterization of in vitro canine DC. 相似文献
970.