全文获取类型
收费全文 | 136034篇 |
免费 | 7808篇 |
国内免费 | 70篇 |
专业分类
林业 | 5587篇 |
农学 | 4657篇 |
基础科学 | 863篇 |
17549篇 | |
综合类 | 19002篇 |
农作物 | 5140篇 |
水产渔业 | 7123篇 |
畜牧兽医 | 73136篇 |
园艺 | 1806篇 |
植物保护 | 9049篇 |
出版年
2020年 | 1185篇 |
2019年 | 1418篇 |
2018年 | 2242篇 |
2017年 | 2496篇 |
2016年 | 2303篇 |
2015年 | 2009篇 |
2014年 | 2459篇 |
2013年 | 5756篇 |
2012年 | 4372篇 |
2011年 | 5198篇 |
2010年 | 3520篇 |
2009年 | 3562篇 |
2008年 | 5168篇 |
2007年 | 4994篇 |
2006年 | 4664篇 |
2005年 | 4279篇 |
2004年 | 4139篇 |
2003年 | 4187篇 |
2002年 | 3824篇 |
2001年 | 4781篇 |
2000年 | 4645篇 |
1999年 | 3749篇 |
1998年 | 1473篇 |
1997年 | 1453篇 |
1996年 | 1345篇 |
1995年 | 1600篇 |
1994年 | 1329篇 |
1993年 | 1362篇 |
1992年 | 2766篇 |
1991年 | 2902篇 |
1990年 | 2868篇 |
1989年 | 2901篇 |
1988年 | 2612篇 |
1987年 | 2594篇 |
1986年 | 2539篇 |
1985年 | 2401篇 |
1984年 | 1957篇 |
1983年 | 1720篇 |
1982年 | 1154篇 |
1979年 | 1650篇 |
1978年 | 1287篇 |
1977年 | 1137篇 |
1976年 | 1101篇 |
1975年 | 1164篇 |
1974年 | 1357篇 |
1973年 | 1449篇 |
1972年 | 1379篇 |
1971年 | 1197篇 |
1970年 | 1248篇 |
1969年 | 1148篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
961.
962.
P. V. Tertuliano Marinho C. C. Zani F. De Biasi M. V. Bahr Arias 《The Journal of small animal practice》2014,55(10):538-541
An adult male crossbred dog was referred with a history of a road traffic accident that took place 1 month earlier. Neurological examination revealed paraplegia with absent nociception in the pelvic limbs. On epaxial palpation, significant curvature of the anatomical axis of the spine between the third and fourth lumbar vertebrae was observed, with the presence of a bone end almost piercing the dog's skin. Survey radiographs of the lumbar spine revealed severe dislocation between L3 and L4 vertebrae. During surgery, the spinal cord was not visible between the dislocated segments. Because of difficulties in reducing the lumbar luxation during surgery, vertebrectomy and vertebral shortening were performed. After alignment between vertebrae L3 and L5, eight cortical orthopaedic screws and bone cement were used for fixation. After 30 days, the dog started to use a wheelchair and was considered by its owner to have a good quality of life with no evidence of pain. To the authors’ knowledge, this is the first case of severe luxation treated by total vertebrectomy and spine shortening in a dog. This surgery can be considered as an option in the management of severe spine luxation when the spinal cord is physically transected. 相似文献
963.
R.C. Windsor B.K. Sturges K.M. Vernau W. Vernau 《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》2009,23(2):275-281
Background: Marked eosinophilic meningitis or meningoencephalomyelitis (EME) is rarely reported in dogs and the cause is usually undetermined. Long-term prognosis for dogs with cerebrospinal fluid (CSF) eosinophilia is variable.
Animals: Twenty-three client-owned dogs.
Methods: Retrospective case series. Dogs with eosinophilic CSF, defined as total nucleated cell count (TNCC) >3 cells/μL with >20% eosinophils, were identified by a computerized search of all dogs having cisternal and/or lumbar CSF analyzed as part of the diagnostic workup between 1992 and 2007.
Results: TNCC in CSF ranged from 4 to 4,740 cells/μL (median 84 cells/μL, reference range ≤3 cells/μL), with 22 to 95% (median 78%) eosinophils in the differential count. An infectious agent was identified on necropsy in 4 of 23 (17%) dogs ( Cryptococcus neoformans [n = 2], Neospora caninum [n = 1], and Baylisascaris procyonis [n = 1]). Each of these dogs had progressive neurologic deterioration. Sixteen dogs had idiopathic EME. Magnetic resonance imaging (MRI) findings were abnormal in 7 of 13 dogs with EME; 2 dogs had focal lesions and 5 dogs had multifocal lesions. Clinical signs in 12 of 16 (75%) dogs with idiopathic EME resolved with prednisone treatment. Three dogs with acute intervertebral disc herniations recovered after decompressive surgery alone.
Conclusions: Idiopathic EME is a common cause of eosinophilic pleocytosis in dogs. MRI findings are variable. Infectious causes of EME were less common and had a poor prognosis. 相似文献
Animals: Twenty-three client-owned dogs.
Methods: Retrospective case series. Dogs with eosinophilic CSF, defined as total nucleated cell count (TNCC) >3 cells/μL with >20% eosinophils, were identified by a computerized search of all dogs having cisternal and/or lumbar CSF analyzed as part of the diagnostic workup between 1992 and 2007.
Results: TNCC in CSF ranged from 4 to 4,740 cells/μL (median 84 cells/μL, reference range ≤3 cells/μL), with 22 to 95% (median 78%) eosinophils in the differential count. An infectious agent was identified on necropsy in 4 of 23 (17%) dogs ( Cryptococcus neoformans [n = 2], Neospora caninum [n = 1], and Baylisascaris procyonis [n = 1]). Each of these dogs had progressive neurologic deterioration. Sixteen dogs had idiopathic EME. Magnetic resonance imaging (MRI) findings were abnormal in 7 of 13 dogs with EME; 2 dogs had focal lesions and 5 dogs had multifocal lesions. Clinical signs in 12 of 16 (75%) dogs with idiopathic EME resolved with prednisone treatment. Three dogs with acute intervertebral disc herniations recovered after decompressive surgery alone.
Conclusions: Idiopathic EME is a common cause of eosinophilic pleocytosis in dogs. MRI findings are variable. Infectious causes of EME were less common and had a poor prognosis. 相似文献
964.
965.
Sverine Tasker Iain R. Peters Kostas Papasouliotis Simon M. Cue Barbara Willi Regina Hofmann-Lehmann Timothy J. Gruffydd-Jones Toby G. Knowles Michael J. Day Chris R. Helps 《Veterinary microbiology》2009,139(3-4):323-332
The aim of this study was to compare blood copy, haematological and glucose values between cats experimentally infected with either Mycoplasma haemofelis (Group HF: 10 cats), ‘Candidatus M. haemominutum’ (Group HM: 3 cats) or ‘Candidatus M. turicensis’ (Group TU: 3 cats). Blood samples were collected regularly up to 85 days post-infection (DPI) for haemoplasma real-time quantitative PCR, haematology, Coombs’ testing and blood glucose measurement. Statistical analysis was performed using a general linear model (ANOVA) appropriate for a repeated measures experiment with significance set as P < 0.05. Cats in Group TU had significantly lower blood copy numbers than cats in Group HF (P < 0.001) and HM (P < 0.001). All Group HF cats developed anaemia (often severe), macrocytosis and evidence of erythrocyte-bound antibodies whereas Groups HM and TU cats did not. Group HF had significantly lower PCVs, haemoglobin concentrations and red blood cell counts, and significantly higher mean cell volumes, than Groups HM and TU. In Group HF, erythrocyte-bound antibodies reactive at 4 °C (both IgM and IgG) appeared between 8 and 22 DPI and persisted for two to four weeks, whereas those reactive at 37 °C (primarily IgG) appeared between 22 and 29 DPI and persisted for one to five weeks. In most cats antibodies appeared after the fall in haemoglobin started. Although Group TU had significantly lower glucose concentrations than Groups HF (P = 0.006) and HM (P = 0.027), mean blood glucose concentrations remained within the reference range in all groups. This study demonstrates that M. haemofelis infection, in contrast to ‘Candidatus M. haemominutum’ and ‘Candidatus M. turicensis’ infection, can result in a severe macrocytic anaemia and the development of cold and warm reactive erythrocyte-bound antibodies. 相似文献
966.
967.
968.
969.
970.
为了研究日粮的蛋白质和纤维水平对仔猪生产性能和健康状况的互作,特选择96头35日龄的仔猪(体重为9.11±0.60kg),分32个栏饲养,每栏3头,分成4个日粮处理组,饲喂期21d。在设定的2×2因子处理中,4种日粮以大米、奶制品和大豆粕为基础配制,日粮蛋白质设两个水平(15.4%与19.4%,风干基),纤维也设两个水平[低水平纤维(LF)为含5.3%中性洗涤纤维,高水平纤维(HF)为含7.15%中性洗涤纤维,风干基]。高水平纤维日粮组在基础日粮中添加了40g/kg的小麦麸和20g/kg的甜菜浆。每周测定动物生产性能,试验第1天和最后一天收集粪样进行微生物学分析,并且按1(液态)到4(硬实)的评分体系对粪便进行评分。在试验最后1d,每栏选1头猪采集血液,分析急性期反应蛋白(acute-phase protein)和主要急性期反应蛋白(major acute-phase prot)(即Pig-MAP)的含量,随后进行屠宰,对消化道(包括内容物)进行称重,并进行结肠组织学分析。饲喂高水平纤维日粮的仔猪具有较大的平均日增重(390g与457g,P≤0.001)和大肠重量(以占体重比例衡量为4.4%与5.4%,P≤0.05)。这与较高的短链脂肪酸浓度(尤其是乙酸和丁酸)、较少的大肠杆菌数量(每克粪便含7.77与6.86logcfu,P≤0.05)和较高乳酸杆菌与肠道细菌比(0.76与1.37,P≤0.05)是相符的。虽然日粮蛋白质水平没有改变猪的生产性能,但是20%的蛋白质水平提高(P≤0.05)了小肠(6.5与7.7)和大肠(3.8与4.3)的相对重量(占体重的百分比)。在大肠内,含20%蛋白质的日粮使仔猪杯状细胞数量增加(4.6/100与5.4/100μm;P≤0.05),并使肠上皮内淋巴细胞数量减少(1.8/100与1.3/100μm;P≤0.05)。在健康状况方面,提高日粮纤维水平所产生的效果与日粮中的蛋白质含量有关。在含16%蛋白质的日粮中增加纤维水平可降低粪便评分值、增加抗生素治疗次数,然而在? 相似文献