全文获取类型
收费全文 | 5519篇 |
免费 | 248篇 |
国内免费 | 4篇 |
专业分类
林业 | 423篇 |
农学 | 183篇 |
基础科学 | 35篇 |
1101篇 | |
综合类 | 877篇 |
农作物 | 231篇 |
水产渔业 | 344篇 |
畜牧兽医 | 2002篇 |
园艺 | 176篇 |
植物保护 | 399篇 |
出版年
2023年 | 33篇 |
2022年 | 54篇 |
2021年 | 84篇 |
2020年 | 135篇 |
2019年 | 126篇 |
2018年 | 135篇 |
2017年 | 121篇 |
2016年 | 130篇 |
2015年 | 110篇 |
2014年 | 131篇 |
2013年 | 259篇 |
2012年 | 303篇 |
2011年 | 382篇 |
2010年 | 220篇 |
2009年 | 168篇 |
2008年 | 310篇 |
2007年 | 317篇 |
2006年 | 291篇 |
2005年 | 289篇 |
2004年 | 264篇 |
2003年 | 271篇 |
2002年 | 256篇 |
2001年 | 64篇 |
2000年 | 71篇 |
1999年 | 82篇 |
1998年 | 56篇 |
1997年 | 53篇 |
1996年 | 54篇 |
1995年 | 39篇 |
1994年 | 47篇 |
1993年 | 49篇 |
1992年 | 39篇 |
1991年 | 46篇 |
1990年 | 46篇 |
1989年 | 42篇 |
1988年 | 38篇 |
1987年 | 39篇 |
1986年 | 54篇 |
1985年 | 32篇 |
1984年 | 43篇 |
1983年 | 35篇 |
1982年 | 36篇 |
1981年 | 27篇 |
1980年 | 20篇 |
1979年 | 23篇 |
1978年 | 27篇 |
1977年 | 26篇 |
1975年 | 20篇 |
1973年 | 24篇 |
1972年 | 20篇 |
排序方式: 共有5771条查询结果,搜索用时 15 毫秒
61.
Thomas Flegel Peter B?ttcher Michaele Alef Ingmar Kiefer Eberhard Ludewig Jens Thielebein Vera Grevel 《Journal of zoo and wildlife medicine》2008,39(3):468-471
A 13-yr-old Amur tiger (Panthera tigris altaica) was presented for an acute onset of paraplegia. Spinal imaging that included plain radiographs, myelography, and computed tomography performed under general anesthesia revealed lateralized spinal cord compression at the intervertebral disc space L4-5 caused by intervertebral disc extrusion. This extrusion was accompanied by an extensive epidural hemorrhage from L3 to L6. Therefore, a continuous hemilaminectomy from L3 to L6 was performed, resulting in complete decompression of the spinal cord. The tiger was ambulatory again 10 days after the surgery. This case suggests that the potential benefit of complete spinal cord decompression may outweigh the risk of causing clinically significant spinal instability after extensive decompression. 相似文献
62.
Herdt TH Neuder LM Green CD Fordyce MG Dill KJ Mahoney JH 《Journal of veterinary medical education》2008,35(1):48-50
Cooperative programs with agribusiness offer opportunities for colleges of veterinary medicine to expand their instructional programs in agricultural practice. Agribusinesses associated with livestock agriculture recognize the importance of veterinary medicine in maintaining a vibrant and successful industry. Stewardship of corporate support involves close communication with advocates within the companies, providing them with documentation of the potential effects of corporate investments. This article describes the creation of the Michigan State University (MSU) Training Center for Dairy Professionals, a key aspect of which was the identification of innovative and productive areas of mutual interest and benefit. In addition to supporting the dairy industry by training veterinary students, the program offers specific benefits to investors, including the use of MSU facilities and direct participation in veterinary instruction. 相似文献
63.
SONOGRAPHY OF THE EQUINE PALMAR METACARPAL SOFT TISSUES 总被引:2,自引:0,他引:2
It was hypothesized that ultrasonography may be a sensitive method for identifying pathologic changes in the tendons and ligaments of the palmar metacarpus of the horse. The palmar meta-carpi of equine cadavers and live horses were examined sonographically. The advantages and disadvantages of various ultrasound scanning techniques and the normal appearance of longitudinal and transverse palmar metacarpal sonograms are described. 相似文献
64.
65.
Goulle F Meige F Durieux F Malet C Toulza O Isard PF Peiffer RL Dulaurent T 《Veterinary ophthalmology》2011,14(Z1):93-98
Objective To describe a case of intracranial meningioma causing visual impairment in a cat, successfully treated by surgery. Procedures An adult neutered male domestic cat was referred with a 10‐month history of progressive visual impairment and altered behavior. Investigations included physical, ophthalmologic and neurological examinations as well as hematology, serum biochemistry and CT scan of the head. Results The menace response was absent in the left eye and decreased in the right eye. Electroretinograms were normal on both eyes, as was ophthalmic examination, ruling out an ocular cause and allowing a presumptive diagnosis of partial amaurosis due to a post‐retinal lesion. CT scan demonstrated a large sessile extra axial mass along the right parietal bone and thickening of the adjacent bone. Cerebrospinal fluid was not collected because high intracranial pressure represented a risk for brain herniation. A right rostrotentorial craniectomy was performed to remove the tumor. Ten days after surgery, vision was improved, neurological examination was normal and normal behavior was restored. Ten months after surgery, ophthalmological examination showed no visual deficit and CT scan did not reveal any sign of recurrence. Conclusion Advanced imaging techniques allow veterinarians to detect early cerebral diseases and to provide specific treatment when it is possible. In cases of feline amaurosis due to intracranial meningioma, the vital prognosis is good while the visual prognosis is more uncertain, but recovery of normal vision and normal behavior is possible as demonstrated in the present case. 相似文献
66.
67.
Thomas Alter Rita Margarete Weber Ahmad Hamedy Gerhard Glünder 《Veterinary microbiology》2011,147(1-2):90-95
Nineteen flocks of four poultry species were monitored at a veterinary field station to investigate the distribution and spread of Campylobacter genotypes between sequential and adjacent flocks. Caecal and liver samples were obtained at frequent intervals from birds of all flocks and examined for Campylobacter. Amplified fragment length polymorphism (AFLP) analysis was performed to genotype Campylobacter isolates. Of the 1643 caecal and liver samples investigated, 452 (27.5%) caecal samples and 11 (0.7%) liver samples contained Campylobacter. Of the caecal isolates 76.3% were identified as Campylobacter jejuni and 23.7% were identified as Campylobacter coli. Poultry flocks were largely colonized by more than one AFLP type and an intense exchange of Campylobacter genotypes between different poultry flocks occurred. These findings indicate that multiple genotypes can constitute the Campylobacter population within single poultry flocks, hinting to different sources of exposure and/or genetic drifts within the Campylobacter population. Nevertheless, in most flocks single Campylobacter genotypes predominated. Some strains superseded others resulting in colonization by successive Campylobacter genotypes during the observation period. In conclusion, the data demonstrate that the large genetic diversity of Campylobacter must be considered in epidemiological evaluations and microbial risk assessments of Campylobacter in poultry. 相似文献
68.
C.B. Thomas D.E. Jasper M.H. Rollins R.B. Bushnell E.J. Carroll 《Preventive veterinary medicine》1983,1(3):227-242
The bedding populations of Enterobacteriaceae, rainfall and mastitis incidence due to Enterobacteriaceae were studied over 12 months on one California dairy. The bedding material used was a mixture of sawdust and wood shavings. Over the 12-month period Escherichia coli was isolated from 59 mastitic milk samples and Klebsiella pneumoniae from 44. The bedding population, rainfall and mastitis incidence data were analyzed by fitting log-linear models. The results of these analyses indicated that rainfall, bedding populations of E. coli and E. coli mastitis incidence were statistically independent, while a strong association existed between rainfall and K. pneumoniae bedding populations and separately between K. pneumoniae bedding populations and the incidence of K. pneumoniae mastitis. 相似文献
69.
A young African grey parrot was presented for necropsy following a 3-to-4-day illness consisting of lethargy, anorexia, and diarrhea. A disseminated necrotizing hepatopathy was evident upon histologic examination of the liver. Aggregates of approximately 70-nm-diameter viral particles having morphology consistent with the family Reoviridae were demonstrated by thin-section and negative-staining electron microscopy. 相似文献
70.
Ccile De Guio Emilie Sgard‐Weisse Aurlie Thomas‐Cancian Michael Schramme 《Veterinary radiology & ultrasound》2019,60(2):167-175
The metacarpophalangeal joint is a common site of pain in horses. Little information is available about bone marrow lesions in the distal condyles of the third metacarpal bone in sports and pleasure horses. Aims of this prospective, retrospective, observational study were to evaluate the prevalence of bone marrow lesions in the distal condyles of the third metacarpal bone, to describe their anatomic distribution and to correlate lesions with the presence of lameness and the level and type of activity. All sports and pleasure horses undergoing standing low‐field MRI of the front fetlock region between 2009 and 2016 were included and divided into three lameness groups according to the results of diagnostic analgesia. Bone marrow lesions were analyzed and graded by one reader. Grades were compared between anatomical locations and between lameness groups. A total of 166 horses were sampled. The prevalence of bone marrow lesions was 76.5% (127/166). The dorsal aspects of the medial condyle (31%, 39/127) and of the sagittal ridge (28%, 36/127) were the most commonly affected locations. There was no significant difference between both forelimbs (lame limb and non‐lame limb) of the same horse. Lesion severity was neither significantly associated with the lameness group nor with the type or level of activity. The prevalence of bone marrow lesions in the distal condyles of the third metacarpal bone is high in this population and the clinical significance is not always clear. Further studies are required to elucidate the clinical significance of this finding in sports and pleasure horses. 相似文献