全文获取类型
收费全文 | 70077篇 |
免费 | 4019篇 |
国内免费 | 1283篇 |
专业分类
林业 | 3546篇 |
农学 | 3451篇 |
基础科学 | 1250篇 |
8505篇 | |
综合类 | 13173篇 |
农作物 | 2652篇 |
水产渔业 | 3183篇 |
畜牧兽医 | 34275篇 |
园艺 | 994篇 |
植物保护 | 4350篇 |
出版年
2021年 | 689篇 |
2020年 | 738篇 |
2019年 | 811篇 |
2018年 | 1126篇 |
2017年 | 1233篇 |
2016年 | 1158篇 |
2015年 | 1198篇 |
2014年 | 1267篇 |
2013年 | 3115篇 |
2012年 | 2235篇 |
2011年 | 2687篇 |
2010年 | 1888篇 |
2009年 | 1845篇 |
2008年 | 2410篇 |
2007年 | 2413篇 |
2006年 | 2275篇 |
2005年 | 2004篇 |
2004年 | 1730篇 |
2003年 | 1849篇 |
2002年 | 1854篇 |
2001年 | 2153篇 |
2000年 | 2071篇 |
1999年 | 1726篇 |
1998年 | 876篇 |
1997年 | 802篇 |
1996年 | 756篇 |
1995年 | 848篇 |
1994年 | 755篇 |
1993年 | 730篇 |
1992年 | 1348篇 |
1991年 | 1468篇 |
1990年 | 1345篇 |
1989年 | 1345篇 |
1988年 | 1221篇 |
1987年 | 1173篇 |
1986年 | 1215篇 |
1985年 | 1207篇 |
1984年 | 967篇 |
1983年 | 906篇 |
1979年 | 896篇 |
1978年 | 702篇 |
1977年 | 694篇 |
1976年 | 711篇 |
1975年 | 714篇 |
1974年 | 866篇 |
1973年 | 842篇 |
1972年 | 812篇 |
1971年 | 727篇 |
1970年 | 769篇 |
1969年 | 733篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
992.
993.
The effect of lactic acid bacterial starter culture and chemical additives on wilted rice straw silage 下载免费PDF全文
Yan‐Su Wang Wei Shi Lin‐Ting Huang Cheng‐Long Ding Chuan‐Chao Dai 《Animal Science Journal》2016,87(4):525-535
Lactic acid bacteria (LAB) are suitable for rice straw silage fermentation, but have been studied rarely, and rice straw as raw material for ensiling is difficult because of its disadvantages, such as low nutrition for microbial activities and low abundances of natural populations of LAB. So we investigated the effect of application of LAB and chemical additives on the fermentation quality and microbial community of wilted rice straw silage. Treatment with chemical additives increased the concentrations of crude protein (CP), water soluble carbohydrate (WSC), acetic acid and lactic acid, reduced the concentrations of acid detergent fiber (ADF) and neutral detergent fiber (NDF), but did not effectively inhibit the growth of spoilage organisms. Inoculation with LABs did not improve the nutritional value of the silage because of poor growth of LABs in wilted rice straw. Inoculation with LAB and addition of chemical materials improved the quality of silage similar to the effects of addition of chemical materials alone. Growth of aerobic and facultatively anaerobic bacteria was inhibited by this mixed treatment and the LAB gradually dominated the microbial community. In summary, the fermentation quality of wilted rice straw silage had improved by addition of LAB and chemical materials. 相似文献
994.
INVITED REVIEW—IMAGE REGISTRATION IN VETERINARY RADIATION ONCOLOGY: INDICATIONS,IMPLICATIONS, AND FUTURE ADVANCES 下载免费PDF全文
Yang Feng Jessica Lawrence Kun Cheng Dean Montgomery Lisa Forrest Duncan B. Mclaren Stephen McLaughlin David J. Argyle William H. Nailon 《Veterinary radiology & ultrasound》2016,57(2):113-123
The field of veterinary radiation therapy (RT) has gained substantial momentum in recent decades with significant advances in conformal treatment planning, image‐guided radiation therapy (IGRT), and intensity‐modulated (IMRT) techniques. At the root of these advancements lie improvements in tumor imaging, image alignment (registration), target volume delineation, and identification of critical structures. Image registration has been widely used to combine information from multimodality images such as computerized tomography (CT), magnetic resonance imaging (MRI), and positron emission tomography (PET) to improve the accuracy of radiation delivery and reliably identify tumor‐bearing areas. Many different techniques have been applied in image registration. This review provides an overview of medical image registration in RT and its applications in veterinary oncology. A summary of the most commonly used approaches in human and veterinary medicine is presented along with their current use in IGRT and adaptive radiation therapy (ART). It is important to realize that registration does not guarantee that target volumes, such as the gross tumor volume (GTV), are correctly identified on the image being registered, as limitations unique to registration algorithms exist. Research involving novel registration frameworks for automatic segmentation of tumor volumes is ongoing and comparative oncology programs offer a unique opportunity to test the efficacy of proposed algorithms. 相似文献
995.
Comparison of bupivacaine and dexmedetomidine femoral and sciatic nerve blocks with bupivacaine and buprenorphine epidural injection for stifle arthroplasty in dogs 下载免费PDF全文
996.
The 5‐lipoxygenase inhibitor tepoxalin induces oxidative damage and altered PTEN status prior to apoptosis in canine osteosarcoma cell lines 下载免费PDF全文
J. P. Loftus D. Cavatorta J. J. Bushey C. B. Levine C. S. Sevier J. J. Wakshlag 《Veterinary and comparative oncology》2016,14(2):e17-e30
The 5‐lipoxygenase (5‐LOX) inhibitor tepoxalin has been shown to slow canine osteosarcoma (OSA) tumour xenografts growth, yet the mechanisms are poorly elucidated. Further examination of tepoxalin in canine OSA cell lines shows that tepoxalin treated cells undergo apoptosis through caspase‐3 activation and annexin staining. Interestingly, apoptosis is superseded by an increase in reactive oxygen species (ROS), as measured by activation of dihydrorhodamine 123 and mitosox. This increase in ROS appears to be related to the 5‐LOX inhibitor regardless of cellular 5‐LOX status, and was not observed after treatment with the tepoxalin metabolite RWJ20142. Additionally, 5‐LOX inhibition by tepoxalin appears to increase phosphatase and tensin (PTEN) homolog activity by preventing its alkylation or oxidation. PTEN modification or inhibition allows phosphoinositide‐3 (PI3) kinase activity thereby heightening activation of protein kinase B (AKT) phosphorylation. Our data suggest that off target oxidation and LOX inhibition play roles in the apoptotic response. 相似文献
997.
998.
Canine transmissible venereal tumour (CTVT) is a contagious venereal tumour of dogs, commonly observed in dogs that are in close contact with one another, or in stray and wild dogs that exhibit unrestrained sexual activity. CTVT represents a unique, naturally transmissible, contagious tumour, where the mutated tumour cell itself is the causative agent and perpetuates as a parasitic allograft in the host. Clinical history, signalment and cytological features are often obvious for establishing a diagnosis though biopsy and histological examination may be needed in atypical cases. Most cases are curable with three intravenous injections of vincristine sulphate at weekly intervals. The role of stray and wild dogs makes the disease difficult to control and necessitates sustained animal birth control in stray dogs along with prompt therapy of the affected dogs. This review captures the manifold developments in different areas embracing this fascinating tumour, including its biology, diagnosis and therapeutic alternatives. 相似文献
999.
Severe hyperkalemia presenting with wide‐complex tachycardia in a puppy with acute kidney injury secondary to leptospirosis 下载免费PDF全文
1000.