全文获取类型
收费全文 | 601篇 |
免费 | 34篇 |
专业分类
林业 | 36篇 |
农学 | 12篇 |
98篇 | |
综合类 | 52篇 |
农作物 | 15篇 |
水产渔业 | 25篇 |
畜牧兽医 | 344篇 |
园艺 | 21篇 |
植物保护 | 32篇 |
出版年
2023年 | 13篇 |
2022年 | 13篇 |
2021年 | 18篇 |
2020年 | 30篇 |
2019年 | 35篇 |
2018年 | 15篇 |
2017年 | 14篇 |
2016年 | 19篇 |
2015年 | 18篇 |
2014年 | 19篇 |
2013年 | 26篇 |
2012年 | 43篇 |
2011年 | 55篇 |
2010年 | 30篇 |
2009年 | 21篇 |
2008年 | 32篇 |
2007年 | 40篇 |
2006年 | 45篇 |
2005年 | 26篇 |
2004年 | 32篇 |
2003年 | 28篇 |
2002年 | 22篇 |
2001年 | 5篇 |
2000年 | 3篇 |
1999年 | 4篇 |
1998年 | 1篇 |
1997年 | 3篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1993年 | 3篇 |
1992年 | 2篇 |
1991年 | 2篇 |
1990年 | 2篇 |
1988年 | 2篇 |
1987年 | 1篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1983年 | 3篇 |
1982年 | 1篇 |
1981年 | 2篇 |
1975年 | 1篇 |
1973年 | 1篇 |
1950年 | 1篇 |
排序方式: 共有635条查询结果,搜索用时 311 毫秒
91.
Sita S. Withers Katherine A. Skorupski Daniel York Jin W. Choi Kevin D. Woolard Renee Laufer‐Amorim Ellen E. Sparger Carlos O. Rodriguez Stephen J. McSorley Arta M. Monjazeb William J. Murphy Robert J. Canter Robert B. Rebhun 《Veterinary and comparative oncology》2019,17(1):49-60
Immunotherapeutic strategies have shown promise for the treatment of canine osteosarcoma (cOSA). Very little is known about the immune microenvironment within cOSA, however, limiting our ability to identify potential immune targets and biomarkers of therapeutic response. We therefore prospectively assessed the disease‐free interval (DFI) and overall survival time (ST) of 30 dogs with cOSA treated with amputation and six doses of adjuvant carboplatin. We then quantified lymphocytic (CD3+, FOXP3+) and macrophage (CD204+) infiltrates within the primary tumours of this cohort using immunohistochemistry, and evaluated their association with outcome. Overall, the median DFI and ST were 392 and 455 days, respectively. The median number of CD3+ and FOXP3+ infiltrates were 45.8 cells/mm2 (4.6‐607.6 cells/mm2) and 8.5 mm2 (0‐163.1 cells/mm2), respectively. The median area of CD204+ macrophages was 4.7% (1.3%‐23.3%), and dogs with tumours containing greater than 4.7% CD204+ macrophages experienced a significantly longer DFI (P = 0.016). Interestingly, a significantly lower percentage of CD204+ macrophages was detected in cOSA arising from the proximal humerus compared to other appendicular bone locations (P = 0.016). Lymphocytic infiltrates did not appear to correlate with outcome in cOSA. Overall, our findings suggest that macrophages may play a role in inhibiting cOSA progression, as has been suggested in human osteosarcoma. 相似文献
92.
Katherine C. Kral-OBrien Ryan F. Limb Torre J. Hovick Jason P. Harmon 《Strength and Conditioning Journal》2019,72(2):301-309
Rangeland management strategies impact biodiversity, the quality and quantity of ecosystem services, and overall rangeland resiliency. Previous management strategies, coupled with climate change, have led to widespread invasion by Kentucky bluegrass (Poa pratensis; bluegrass) in the Northern Great Plains, United States. Bluegrass invasions are expected to have detrimental impacts on biodiversity conservation and ecosystem services provided by rangelands. Yet none have investigated how bluegrass invasions influence pollinator populations, which are a prominent conservation concern and provide ecosystem services. We measured the impact of bluegrass invasion on mixed-grass prairie forb and butterfly communities. Obligate grassland butterflies, those that rely on grasslands, decreased as bluegrass cover increased, including the threatened Hesperia dacotae. Conversely, the abundance of facultative grassland butterflies, those found in grasslands but not fully dependent on them for their life history, increased as bluegrass increased. Moreover, plant species diversity and flowering forb species richness decreased as bluegrass cover increased. Overall, bluegrass invasion led to butterfly and plant community simplification, signaling a loss of biodiversity and potentially ecosystem services. Our research is the first to quantify how grassland butterflies and the floral resources they depend on are negatively impacted by bluegrass invasion. Resource managers should adopt management strategies that reduce bluegrass cover and improve nectar and host resources for obligate grassland butterflies. Management choices that removed disturbance regimes inherent to the Northern Great Plains (i.e., fire and grazing) led to bluegrass dominance in the region. Therefore, restoring disturbance regimes may be one way to reduce bluegrass and benefit pollinator populations. 相似文献
93.
94.
Julien J Labruyère Claudia Hartley Katherine Rogers Graham Wetherill J Fraser McConnell Ruth Dennis 《Veterinary radiology & ultrasound》2008,49(2):165-171
Vitreous degeneration is common in dogs and may be associated with cataract formation. Vitreous degeneration may be identified using B-mode ultrasonography and appears as multiple, small, motile, point-like echoes within the vitreous cavity. In humans, vitreous degeneration has also been observed in normal aging eyes but the incidence of vitreous degeneration in dogs without cataract has not previously been documented. The purpose of this study was to describe the ultrasonographic appearance of vitreous degeneration and to investigate its incidence in a population of dogs without cataract or other apparent eye disease. The eyes of 62 dogs were evaluated as part of a prospective study. All dogs underwent ophthalmological and ultrasonographic examinations and vitreal changes were graded on ultrasonography using a predetermined grading scheme. Vitreous degeneration was found in 20% (23/114) of the eyes on ultrasonographic examination but in only 8% (9/114) of eyes on direct ophthalmoscopy. Sensitivity and specificity of ophthalmoscopy using ultrasonography as a gold standard were respectively, 39% and 100%. Vitreal syneresis and asteroid hyalosis could be distinguished according to their ultrasonographic characteristics. The probability of having vitreous degeneration increased with the age of the dog (odds ratio = 6.7 for dogs of 7 + years compared with 0-6 years) and also increased in females compared with males (odds ratio = 3.6). Vitreous degeneration, especially mild vitreal syneresis, is not uncommon in normal dogs; it was shown to be an age-related condition and its significance should not be overinterpreted on ocular ultrasonography. 相似文献
95.
96.
97.
98.
99.
Meagan M. Coneybeer-Roberts Katherine M. Jennings 《International Journal of Fruit Science》2016,16(3):301-309
Field studies were conducted in 2007 and 2008 in North Carolina to determine the response of the weed Maryland meadowbeauty and blueberry to flumioxazin PRE (pre-emergence). No injury to non-bearing (blueberry plants not mature enough to produce fruit) or bearing (blueberry plants mature enough to produce fruit) blueberry from flumioxazin PRE was observed. In non-bearing blueberry, control of meadowbeauty was greater than 97% 90 DAT (days after treatment) with the registered rate of 0.42 kg ai ha–1 flumioxazin. Across two studies in bearing blueberry, a single application of flumioxazin at 0.42 kg ai ha–1 controlled meadowbeauty 79% to 92% 90 DAT. Flumioxazin at 0.21 kg ai ha–1 applied twice 60 d apart resulted in greater than 96% meadowbeauty control 90 d after the first application. Treatments of flumioxazin applied as a single application or two applications applied sequentially 60 d apart in bearing blueberry had yields ranging from 3150 to 6065 kg ha–1and 3551 to 5735 kg ha–1, respectively, and did not have a negative effect on blueberry yield regardless of application rate compared to the nontreated check. 相似文献
100.
de la Fuente J Atkinson MW Naranjo V Fernández de Mera IG Mangold AJ Keating KA Kocan KM 《Veterinary microbiology》2007,119(2-4):375-381
Anaplasma ovis (Rickettsiales: Anaplasmataceae) is a tick-borne pathogen of sheep, goats and wild ruminants. The genetic diversity of A. ovis strains has not been well characterized due to the lack of sequence information. In this study, we evaluated bighorn sheep (Ovis canadensis) and mule deer (Odocoileus hemionus) from Montana for infection with A. ovis by serology and sequence analysis of the msp4 gene. Antibodies to Anaplasma spp. were detected in 37% and 39% of bighorn sheep and mule deer analyzed, respectively. Four new msp4 genotypes were identified. The A. ovismsp4 sequences identified herein were analyzed together with sequences reported previously for the characterization of the genetic diversity of A. ovis strains in comparison with other Anaplasma spp. The results of these studies demonstrated that although A. ovismsp4 genotypes may vary among geographic regions and between sheep and deer hosts, the variation observed was less than the variation observed between A. marginale and A. phagocytophilum strains. The results reported herein further confirm that A. ovis infection occurs in natural wild ruminant populations in Western United States and that bighorn sheep and mule deer may serve as wildlife reservoirs of A. ovis. 相似文献