全文获取类型
收费全文 | 7169篇 |
免费 | 3383篇 |
国内免费 | 1篇 |
专业分类
林业 | 263篇 |
农学 | 452篇 |
基础科学 | 6篇 |
1585篇 | |
综合类 | 101篇 |
农作物 | 117篇 |
水产渔业 | 2516篇 |
畜牧兽医 | 4181篇 |
园艺 | 22篇 |
植物保护 | 1310篇 |
出版年
2023年 | 15篇 |
2022年 | 5篇 |
2021年 | 137篇 |
2020年 | 481篇 |
2019年 | 1037篇 |
2018年 | 905篇 |
2017年 | 946篇 |
2016年 | 945篇 |
2015年 | 827篇 |
2014年 | 826篇 |
2013年 | 997篇 |
2012年 | 502篇 |
2011年 | 519篇 |
2010年 | 625篇 |
2009年 | 282篇 |
2008年 | 279篇 |
2007年 | 122篇 |
2006年 | 145篇 |
2005年 | 135篇 |
2004年 | 141篇 |
2003年 | 128篇 |
2002年 | 136篇 |
2001年 | 83篇 |
2000年 | 105篇 |
1999年 | 17篇 |
1998年 | 10篇 |
1997年 | 14篇 |
1996年 | 12篇 |
1995年 | 11篇 |
1994年 | 16篇 |
1993年 | 11篇 |
1991年 | 6篇 |
1990年 | 9篇 |
1989年 | 5篇 |
1986年 | 5篇 |
1984年 | 5篇 |
1983年 | 6篇 |
1982年 | 5篇 |
1979年 | 5篇 |
1978年 | 6篇 |
1977年 | 7篇 |
1970年 | 6篇 |
1968年 | 3篇 |
1940年 | 3篇 |
1939年 | 3篇 |
1931年 | 3篇 |
1928年 | 3篇 |
1927年 | 4篇 |
1926年 | 7篇 |
1898年 | 4篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
881.
SUSANNE A. E. B. BOROFFKA CHRISTIANE GÖRIG EDUARDO AURIEMMA MAARTJE H. A. C. PASSON‐VASTENBURG GEORGE VOORHOUT PAUL Y. BARTHEZ 《Veterinary radiology & ultrasound》2008,49(6):540-544
We describe the magnetic resonance (MR) imaging aspects of normal canine optic nerve, the diameter of the optic nerve as measured on MR images, and optimal MR sequences for the evaluation of the optic nerve using a 0.2 T MR unit. Three millimeter contiguous slides of the normal canine orbital region were acquired in transverse and dorsal oblique planes using a variety of tissue weighting sequences. It was apparent that detailed anatomic assessment of the optic nerve can be performed with low‐field MR imaging, but none of the sequences provided unequivocal superior image quality of the optic nerve. The mean diameter of the optic nerve sheath complex was 3.7 mm and of the optic nerve 1.7 mm. The intraorbital and intracanalicular parts of the optic nerve are consistently visible and differentiation between the optic nerve and optic nerve sheath complex is possible using low‐field MR systems. 相似文献
882.
Tien‐Chun WAN Fu‐Yuan CHENG Yu‐Tse LIU Chao‐Ming WANG Ching‐Lin SHYU Chih‐Ming CHEN Liang‐Chuan LIN Ryoichi SAKATA 《Animal Science Journal》2008,79(6):693-698
A novel Bacillus species of Calculus Bovis (cow gallstone) was isolated and identified in this study. Morphological features, bacterial fatty acid analysis using a microbial identification system, carbon source utilization profiles using Biolog system and 16S rDNA sequencing were employed to identify the isolated bacterium. This isolated bacterium was observed to be Gram‐negative, aerobic growing, rod‐shaped and short chain. The results of bacterial fatty acid analysis and physiological characteristics were not matched to the database. The main fatty acids found in the bacterium were 65.96% branched chain saturated fatty acids (iso C11:0, anteiso C11:0 and iso C13:0~anteiso C19:0). The bacterium oxidized 35 carbon sources and weakly responded with 49 of the 95 different carbon sources analyzed with the Biolog identification system. Based on 16S rDNA sequence analysis, this bacterium was classified as a novel Bacillus species. 相似文献
883.
Stuart C Clark‐Price DVM MS Diplomate ACVIM Lysa P Posner DVM Diplomate ACVA 《Veterinary anaesthesia and analgesia》2008,35(6):473-479
ObjectiveTo assess whether recovery from general anesthesia, in an illuminated or a darkened stall, has an effect on time to first movement, time to standing, and recovery score.Study designProspective randomized clinical study.AnimalsTwenty-nine healthy, 2- to 5-year-old horses undergoing surgical correction of dorsal displacement of the soft palate.MethodsEach horse was assigned randomly to recover in either an illuminated (n = 15) or a darkened stall (n = 14). For pre-anesthetic medication, all horses received intravenous (IV) xylazine (0.4 mg kg−1) and butorphanol (0.02 mg kg−1). Anesthesia was induced with midazolam (0.1 mg kg−1) and ketamine (2.2 mg kg−1) IV and maintained on isoflurane in oxygen. Vital parameters, end-tidal CO2 and isoflurane were recorded at 5-minute intervals. At the conclusion of anesthesia, horses were placed in either an illuminated or a darkened stall and xylazine (0.2 mg kg−1) IV was administered at extubation. Video cameras were used to record the horses while they were allowed to recover undisturbed. Video recordings were later viewed and recoveries were evaluated on a 100-point scale by three graders.ResultsHorses in illuminated and darkened recovery stalls were evaluated on total anesthesia time, minimum alveolar concentration hours of isoflurane, time to first movement, time to standing, and total recovery score. There were no significant differences between the two groups in any of the measured parameters.ConclusionRecovering horses in a darkened versus an illuminated recovery stall may provide no benefit.Clinical relevanceDarkening the recovery stalls for horses recovering from general anesthesia may be unnecessary. 相似文献
884.
B. Matharoo‐Ball A. K. Miles C. S. Creaser G. Ball R. Rees 《Veterinary and comparative oncology》2008,6(4):224-247
Companion animals are exposed to similar environmental conditions and carcinogens as humans. In some animal cancers, there also appears to be the same genetic changes associated as in humans. However, little work has been carried out in cancer biomarker identification in animals. The recent dramatic advances in molecular medicine, genomics, proteomics and translational research will allow biomarker identification, which may provide the best strategies for veterinarians and clinicians to combat disease by early diagnosis and administration of effective treatments. Proteomics may have important applications in cancer diagnosis, prognosis and predictive clinical outcome that could directly change clinical practice by affecting critical elemen‐ts of care and management. This review summarizes the advances in proteomics that has propelled us to this exciting age of clinical proteomics, and highlights the future work that is required for this to become a reality. In this review, we will discuss the available proteomic technologies and their limitations, and highlight the key areas of research and how they have been used to discover cancer biomarkers. The principles described here are equally applicable to human and animal disease, but implementation of ‘omic’ technologies requires stringent guidelines for collection of clinical material, the application of analytical techniques and interpretation of the data. 相似文献
885.
886.
887.
888.
889.
890.