全文获取类型
收费全文 | 152篇 |
免费 | 17篇 |
专业分类
林业 | 16篇 |
农学 | 3篇 |
14篇 | |
综合类 | 20篇 |
农作物 | 2篇 |
水产渔业 | 5篇 |
畜牧兽医 | 100篇 |
园艺 | 4篇 |
植物保护 | 5篇 |
出版年
2023年 | 5篇 |
2022年 | 1篇 |
2021年 | 1篇 |
2020年 | 5篇 |
2019年 | 7篇 |
2018年 | 6篇 |
2017年 | 5篇 |
2016年 | 6篇 |
2015年 | 3篇 |
2014年 | 4篇 |
2013年 | 11篇 |
2012年 | 9篇 |
2011年 | 9篇 |
2010年 | 6篇 |
2009年 | 4篇 |
2008年 | 9篇 |
2007年 | 6篇 |
2006年 | 4篇 |
2005年 | 4篇 |
2004年 | 3篇 |
2003年 | 6篇 |
2002年 | 4篇 |
2001年 | 4篇 |
1999年 | 5篇 |
1998年 | 2篇 |
1997年 | 3篇 |
1996年 | 7篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1993年 | 2篇 |
1992年 | 2篇 |
1991年 | 7篇 |
1989年 | 1篇 |
1986年 | 1篇 |
1982年 | 1篇 |
1981年 | 2篇 |
1978年 | 1篇 |
1976年 | 1篇 |
1974年 | 1篇 |
1973年 | 1篇 |
1970年 | 1篇 |
1967年 | 3篇 |
1966年 | 1篇 |
1961年 | 1篇 |
1957年 | 1篇 |
1897年 | 1篇 |
排序方式: 共有169条查询结果,搜索用时 265 毫秒
91.
Polarized and unpolarized neutron scattering was used to measure the wave vector- and frequency-dependent magnetic fluctuations in the normal state (from the superconducting transition temperature, Tc = 35 kelvin, up to 350 kelvin) of single crystals of La1.86Sr0.14CuO4. The peaks that dominate the fluctuations have amplitudes that decrease as T-2 and widths that increase in proportion to the thermal energy, kBT (where kB is Boltzmann's constant), and energy transfer added in quadrature. The nearly singular fluctuations are consistent with a nearby quantum critical point. 相似文献
92.
Pedro Yoelvys de la Fé Rodríguez Luis O. Maroto Martin Eduardo Cruz Muñoz Hein Imberechts Patrick Butaye Bruno Maria Goddeeris Eric Cox 《Tropical animal health and production》2013,45(2):435-440
Intestinal contents of suckling (n?=?45) and newly weaned (n?=?45) piglets, suffering from diarrhea in the province of Villa Clara in Cuba, were tested for viral, bacterial, and parasitic enteropathogens from May to June 2008. At least one enteropathogen was identified in 53.3 % of piglets and enterotoxigenic Escherichia coli (ETEC; 25.6 %) was the major pathogen; mostly STa+/STb+ or F4+/STa+/STb+ ETEC were isolated. The overall occurrence of the rest of pathogens was 10 % for transmissible gastroenteritis virus (TGEV) and Cryptosporidium parvum, 6.7 % for rotavirus A and Isospora suis, 5.6 % for α-toxigenic Clostridium perfringens, 3.3 % for verotoxigenic E. coli (VTEC), and 2.2 % for Salmonella enterica subspecies enterica serovar Newport. TGEV and α-toxigenic C. perfringens were only identified in suckling piglets, while Salmonella Newport and VTEC were only detected in weaned pigs. Porcine epidemic diarrhea virus (PEDV), β-toxigenic C. perfringens, Eimeria spp., and helminths were not identified. Eight kinds of mixed infections were detected in 25 % of enteropathogen positive piglets. ETEC was present in 10 of 12 mixed infections, and TGEV infections were never combined. This survey demonstrates that several enteropathogens are circulating in piggeries located in the province of Villa Clara in Cuba, and that is necessary to improve surveillance, prevention, and control of enteric infections in order to increase production efficiency. 相似文献
93.
94.
Ultrasound during mid‐gestation: Agreement with physical foetal and placental measurements and use in predicting gestational age in sheep 下载免费PDF全文
AK Jones RE Gately KK McFadden ML Hoffman SM Pillai SA Zinn KE Govoni SA Reed 《Reproduction in domestic animals》2017,52(4):649-654
To determine the effects of poor maternal nutrition and litter size on foetal growth during mid‐gestation, pregnant ewes (n = 82) were fed 100%, 60% or 140% of NRC TDN beginning at day 30.2 ± 0.2 of gestation. Transabdominal ultrasound was performed weekly between day 46.0 ± 0.4 and 86.0 ± 0.7 to monitor foetal heart width (HW), umbilical diameter (UMB), rib width (RW) and placentome outer (OD) and inner diameter (ID). Data were analysed with repeated‐measures using the mixed procedure for effects of maternal diet, litter size and gestation, and equations predictive of gestational age were generated using the regression procedure. To determine the agreement of ultrasound measurement and actual size, ewes (n = 20–21) were euthanized at day 45 or 90 to obtain corresponding postmortem measurements for Bland–Altman analysis. The HW, UMB and placentome OD and ID increased with gestation (p < .0001) but were unaffected by maternal diet or litter size (p ≥ .12). Ultrasound underestimated postmortem measurements of HW (14.8%), UMB (7.3%), placentome OD (4.5%) and ID (37.3%) at day 90 of gestation. Ultrasound underestimated RW at day 45 (7.7%) but overestimated RW (23.8%) at day 90, indicating inconsistent bias when reporting RW by ultrasound. Combining the HW, UMB, RW and placentome OD generated the strongest equation predictive of gestational age (R2 = .91). These findings indicate that during mid‐gestation, maternal diet or litter size did not affect HW, UMB or placentome diameters and these factors can be used to estimate gestational age. 相似文献
95.
Lulu Rayhan Khushi SM Rubaiot Abdullah Sanjoy Saha Mohammad Raqibul Hasan Siddique 《Southern Forests》2019,81(1):45-48
Gmelina arborea Roxb. is a fast-growing, deciduous tree species native to Bangladesh. It has been widely planted since 1992 for commercial production of pulpwood in hilly areas of Bangladesh. The purpose of this study was to derive well-fitting allometric models for estimation of aboveground biomass, and carbon and nutrient (nitrogen, phosphorus and potassium) stocks in G. arborea to ensure sustainable production and management of this species. Eight linear models with 64 regression equations were tested for estimation of aboveground biomass, carbon and nutrient stocks in different parts (leaves, branches, bark and stem) of the plant. The best-fitting allometric models were selected in accordance with various relevant statistical criteria. 相似文献
96.
97.
New approaches to nematode control in sheep are urgently needed as anthelmintic drench resistance becomes ever more widespread among worm populations. Here we briefly describe and assess a number of new technologies which will become increasingly important in anti-nematode control programmes in the future. These include vaccines, immunomodulants, strategic grazing practices, the use of biological agents to destroy nematode larvae, biological anthelmintics and targeted silencing of genes regulating nematode development. 相似文献
98.
Kinzel S Hein S Buecker A Krombach GA Kuepper W 《Journal of the American Veterinary Medical Association》2003,223(9):1311-1315
OBJECTIVE: To determine diagnostic features and efficacy of treatment of arthrosis of the cervical articular facet joints between C2 and C3 in Scottish Deerhounds. DESIGN: Retrospective study. ANIMALS: 9 client-owned dogs. PROCEDURE: Medical records of affected dogs were reviewed. Diagnosis was confirmed by results of clinical examination (signs of severe pain from unilateral or bilateral flexion of the cervical vertebral column), radiography, myelography, and computed tomography. Treatment consisted of fluoroscopy-guided intra-articular injection of corticosteroids and lidocaine. RESULTS: Unilateral or bilateral arthrosis of the cervical facet joints between C2 and C3 was detected in all dogs. In 7 dogs, signs of pain were elicited by flexion of the side of the neck in which affected joints were detected radiographically. Two dogs had signs of pain during right lateral flexion, although bilateral lesions were detected. Five dogs had unilateral lesions, and 4 dogs had bilateral lesions; sclerosis and hypertrophy of the articular process were common. Two dogs had bridging of the articular space. Use of computed tomography confirmed the diagnosis. Myelography did not reveal abnormalities of the spinal cord or canal. After treatment, 8 dogs had rapid marked improvement of clinical signs, and 7 dogs remained free of clinical signs for > 4 months. CONCLUSIONS AND CLINICAL RELEVANCE: Arthrosis of the cervical facet joints in Scottish Deerhounds is a severely painful condition for which conventional radiography is a useful screening test. Intra-articular administration of corticosteroids and anesthetic is efficacious, long-lasting, and minimally invasive. 相似文献
99.
Kinzel S Hein S von Scheven C Küpper W 《Berliner und Münchener tier?rztliche Wochenschrift》2002,115(1-2):53-56
Denervation of the canine hip joint capsule is described as a surgical therapy method in the treatment of canine hip joint dysplasia and arthrosis. The goal of this operation is a removal of the pain immediately and a reactivation of the dynamic active component of the hip joint in moving the body forward. Simple removal of the periosteum of the craniolateral acetabulum edge destroys the rami articulares of the cranial glutaeal nerve and the rami articulares dorsalis of the sciatic nerve. Within 10 years now we performed the denervation of the canine hip joint capsule. Evaluation of the post operative clinical course in 269 cases revealed an impressive improvement of lameness due to pain relief in almost 92% of the cases. 相似文献
100.
Retention of aging ewes is a strategy producers may use to maintain or increase flock size. Older ewes can have a higher risk of mortality and health issues, but these may be minimised with early intervention and culling. This retrospective study examined the incidence and causes of mortality and culling in a flock of Merino ewes as they aged from 4.5 to 5.5 until 9.5 to 10.5 years. The annual rate of ewe mortality ranged from 6.2% to 9.9%, with lambing complications being the major source of reported loss. Annual culling rates ranged from 1.6% to 42.8%, the larger rates reflecting opportunistic replacement with younger ewes rather than essential culling to maintain welfare and productivity. The major reasons for culling were low condition score, worn or missing teeth or faulty udders. The incidence of other faults was low. Only 18.3% of ewes remained when aged 9.5–10.5 years and these were fertile (89% pregnant) with a high proportion of multiple fetuses (52%) in their final year, although fleece weight had declined. Younger ewes born in 2004/2005 tended to have lower annual mortality rates than the aged ewes, but 8%–12% were still culled annually. It is concluded that an annual inspection pre-joining of all ewes and preventative culling for health issues is necessary to minimise any increase in mortality and risk to ewe welfare from retaining aging ewes. More frequent inspection will be required as potential health issues develop during the year, as these may not be evident pre-joining. 相似文献