全文获取类型
收费全文 | 842篇 |
免费 | 73篇 |
国内免费 | 1篇 |
专业分类
林业 | 37篇 |
农学 | 23篇 |
基础科学 | 8篇 |
119篇 | |
综合类 | 137篇 |
农作物 | 59篇 |
水产渔业 | 75篇 |
畜牧兽医 | 359篇 |
园艺 | 15篇 |
植物保护 | 84篇 |
出版年
2022年 | 9篇 |
2021年 | 9篇 |
2020年 | 9篇 |
2019年 | 23篇 |
2018年 | 16篇 |
2017年 | 21篇 |
2016年 | 26篇 |
2015年 | 21篇 |
2014年 | 11篇 |
2013年 | 41篇 |
2012年 | 59篇 |
2011年 | 70篇 |
2010年 | 39篇 |
2009年 | 39篇 |
2008年 | 55篇 |
2007年 | 52篇 |
2006年 | 50篇 |
2005年 | 31篇 |
2004年 | 38篇 |
2003年 | 29篇 |
2002年 | 27篇 |
2001年 | 14篇 |
2000年 | 11篇 |
1999年 | 16篇 |
1998年 | 4篇 |
1997年 | 7篇 |
1996年 | 5篇 |
1995年 | 5篇 |
1994年 | 6篇 |
1993年 | 9篇 |
1992年 | 12篇 |
1991年 | 19篇 |
1990年 | 9篇 |
1989年 | 11篇 |
1988年 | 8篇 |
1987年 | 10篇 |
1986年 | 4篇 |
1985年 | 7篇 |
1984年 | 5篇 |
1983年 | 6篇 |
1982年 | 6篇 |
1980年 | 6篇 |
1979年 | 7篇 |
1978年 | 5篇 |
1976年 | 4篇 |
1972年 | 3篇 |
1970年 | 4篇 |
1969年 | 3篇 |
1930年 | 3篇 |
1928年 | 3篇 |
排序方式: 共有916条查询结果,搜索用时 437 毫秒
1.
Recent literature and public discourse emphasize the role of craft breweries in the revitalization process of economically distressed neighborhoods across the U.S. With this, many are reporting rising property values in areas surrounding craft breweries. This research examines the impacts of craft breweries on both residential and commercial property values in a case study of Charlotte, North Carolina. Estimating a series of hedonic models which incorporate a difference‐in‐difference estimator, we find that craft breweries have a positive impact on residential property values. While many areas in close proximity to a craft brewery appear to have been associated with relatively higher price premiums even before the opening of the brewery, breweries tend to add to this premium, especially in center‐city neighborhoods. We find no significant impacts on commercial property values. These results are informative to policy makers considering revising zoning laws and other regulations in efforts to promote the growth of craft breweries and spur economic development in their local economies. 相似文献
2.
David E. Anderson Peter D. Constable Kathleen E. Yvorchuk Neil V. Anderson Guy St-Jean Linda Rock 《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》1994,8(3):207-211
An alpaca and a llama in late stages of gestation were evaluated for lethargy, anorexia, and recumbency. Both camelids had cloudy, white, turbid serum, elevated serum triglyceride (1564, 5658 mg/dL, respectively) and cholesterol (158, 297 mg/dL, respectively) concentrations, and ketonuria. Signs of fetal stress were evident ultrasonographically in the alpaca, and a live cria was delivered by Cesarean section performed under general anesthesia. The alpaca developed severe metabolic acidosis, hepatic lipidosis, and acute renal failure secondary to renal lipidosis and died 36 hours after admission despite medical therapy. Histopathology revealed renal and hepatic lipidosis and neutrophilic pancreatitis. The cria died 72 hours after birth. The llama responded to IV electrolyte, dextrose, and regular crystalline insulin therapy. The pregnancy was maintained, and the llama was discharged from the hospital 20 days after admission. Two months after discharge, the llama gave birth to a live, 5 kg cria. Findings of hypertriglyceridemia, hypercholesterolemia, elevated sorbitol dehydrogenase activity, metabolic acidosis, azotemia, and ketonuria occurred in these two camelids. Based on this report, camelids appear to be similar to both horses and cattle in their response to severe energy imbalances in late gestation. 相似文献
3.
4.
Barber SM McLaughlin BG Fretz PB 《The Canadian veterinary journal. La revue veterinaire canadienne》1983,24(2):46-49
A one month old Quarterhorse colt was presented after a week history of bilateral nasal discharge and respiratory difficulty. The cervical esophagus was greatly dilated, tortuous and filled with diluted milk. A nasogastric tube could not be passed beyond the base of the heart. An aspiration pneumonia was found at postmortem examination and the esophageal segment from the pharynx to the base of the heart was dilated, thin-walled, had degenerative muscular changes, and a reduction in size and number of ganglion cells of the myenteric plexus. Muscular hypertrophy of the terminal esophagus had reduced its lumen size. Some similarities and disparities of this condition to achalasia of man and megaesophagus of dogs are discussed. 相似文献
5.
Hirsch VM McLaughlin BG Parent J 《The Canadian veterinary journal. La revue veterinaire canadienne》1983,24(10):301-304
Lymphosarcoma in a six year old male Doberman pinscher was accompanied by hypercalcemia, generalized osteolysis and renal calcification. Tumor involvement of bone marrow was extensive. The possible pathogenesis of hypercalcemia was thought to be the result of a locally active bone-resorbing factor secreted by the tumor cells. 相似文献
6.
John D. Armstrong Karen J. Millidine Neil B. Metcalfe 《Ecology of Freshwater Fish》2011,20(3):371-376
Abstract – Standard metabolic rate (SMR, closely related to basal and resting metabolism) varies by up to threefold among juvenile Atlantic salmon, Salmo salar L., of similar size at common temperature. Here, consequences of this variation are predicted by combining empirically derived relationships between SMR, specific dynamic action, energy budgets, water velocity, food level in the environment and food availability to fish. The range of velocities across which growth is predicted to occur is inversely related to a fish’s SMR. Growth is positively related to SMR at high but negatively related to it at low‐food levels. The relationship between food level and the range of velocities over which lower SMR fish can grow but higher SMR fish cannot is asymmetrically bi‐phasic and peaked. It is predicted that maternal manipulation of offspring SMR would generate fitness benefits through bet‐hedging against unpredictability in food level and increases in the overall range of velocities that the family of offspring can occupy and thrive in. 相似文献
7.
Josephine A. Dornbusch Laura E. Selmic Pin‐Chieh Huang Jonathan P. Samuelson Eric M. McLaughlin Vincent A. Wavreille Jessica A. Ogden Brittany Abrams Alex Kalamaras Eric Green Eric T. Hostnik Lincoln Every Jason A. Fuerst Ryan Jennings Christopher Premanandan Joshua N. Lorbach Sarah C. Linn Aneesh Alex Janet E. Sorrells Lingxiao Yang Stephen A. Boppart 《Veterinary surgery : VS》2021,50(1):111-120
8.
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
9.
10.
Natural products derived from micro-organisms, plants and animals possess inherent biological properties and are, therefore, an excellent source of lead chemicals on which to base synthesis programmes employing rational design techniques. Only a fraction of the fungal kingdom has been screened systematically for novel metabolites despite their suspected potential. Moreover, the fungi are generally manipulable in laboratory culture systems and, because of their developmental versatility, they offer tremendous potential as sources of novel metabolites. Primary assay systems based on biochemical targets provide an effective means of screening microbial products; such assay systems also efficiently support chemical purification of lead activities and rapid elucidation of new chemical templates. 相似文献