全文获取类型
收费全文 | 1992篇 |
免费 | 98篇 |
国内免费 | 1篇 |
专业分类
林业 | 101篇 |
农学 | 68篇 |
基础科学 | 9篇 |
381篇 | |
综合类 | 246篇 |
农作物 | 145篇 |
水产渔业 | 154篇 |
畜牧兽医 | 742篇 |
园艺 | 53篇 |
植物保护 | 192篇 |
出版年
2023年 | 10篇 |
2022年 | 9篇 |
2021年 | 27篇 |
2020年 | 41篇 |
2019年 | 37篇 |
2018年 | 31篇 |
2017年 | 35篇 |
2016年 | 38篇 |
2015年 | 33篇 |
2014年 | 52篇 |
2013年 | 94篇 |
2012年 | 92篇 |
2011年 | 134篇 |
2010年 | 55篇 |
2009年 | 71篇 |
2008年 | 100篇 |
2007年 | 117篇 |
2006年 | 121篇 |
2005年 | 93篇 |
2004年 | 101篇 |
2003年 | 80篇 |
2002年 | 84篇 |
2001年 | 32篇 |
2000年 | 31篇 |
1999年 | 29篇 |
1998年 | 18篇 |
1997年 | 20篇 |
1996年 | 17篇 |
1995年 | 13篇 |
1994年 | 18篇 |
1993年 | 16篇 |
1992年 | 32篇 |
1991年 | 12篇 |
1990年 | 28篇 |
1989年 | 24篇 |
1988年 | 16篇 |
1987年 | 21篇 |
1986年 | 18篇 |
1985年 | 25篇 |
1984年 | 25篇 |
1982年 | 10篇 |
1981年 | 17篇 |
1980年 | 11篇 |
1979年 | 11篇 |
1978年 | 12篇 |
1976年 | 16篇 |
1975年 | 10篇 |
1974年 | 14篇 |
1973年 | 12篇 |
1967年 | 11篇 |
排序方式: 共有2091条查询结果,搜索用时 0 毫秒
1.
George J. Brewer MD William Schall DVM Robert Dick BS Vilma Yuzbasiyan-Gurkan PhD Michael Thomas DVM George Padgett DVM 《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》1992,6(1):41-43
Inherited canine copper toxicosis is a serious problem in Bedlington terriers and West Highland White terriers, and may also be a problem in other less-studied breeds. Affected dogs become ill at midlife with progressive and ultimately fatal liver disease. Treatments for removal of copper and prevention of copper accumulation are available, but are most effective if begun before the dog becomes ill. Until recently diagnosis has not been available until the dog is 1 year of age, and then only by an invasive liver biopsy with determination of liver copper concentration. The authors studied the use of 64copper for early diagnosis of canine copper toxicosis. Two procedures were evaluated. The first involved measuring the concentration of 64copper in blood 24 hours after oral administration of the radioisotope. At this time, 64copper was associated primarily with ceruloplasmin secreted into the blood by the liver. This procedure is useful in the diagnosis of the human counterpart, Wilson's disease. However, the authors found it to be nondiscriminatory between affected and unaffected dogs. In contrast, the second procedure, which involved measuring 64copper excreted in stool during 48 hours after an intravenous dose of radioisotope, yielded results that differentiated most affected and unaffected dogs. 相似文献
2.
We investigated the effect of vaccination of male beef calves (mean age+/-S.D.: 158+/-31 days) against bovine herpes virus (BHV-1 or IBR virus), bovine respiratory syncitial virus (BRSV), bovine viral diarrhea (BVD) virus and para-influenza (PI(3)) virus on the incidence of respiratory disease during the first forty days after weaning and entering a feed-lot in Portugal. In May 2003, Mertolenga, Preta and mixed-breed calves from 10 different beef herds, were systematically assigned (by order of entrance in a chute) to two treatment groups, before moving to a common feed-lot. One hundred and twenty five male calves were vaccinated with a quadrivalent vaccine (Rispoval 4) and revaccinated after 21-27 days while 148 herdmates were injected with saline (0.9% NaCl) on the same occasions. The incidence and severity of clinical cases of "bovine respiratory disease" (BRD) were evaluated every day during the first 40 days after entering the feed-lot. Morbidity (3% vs. 14%) and mortality (0% vs. 4%) due to BRD were significantly lower in the vaccinated group. Ten days after revaccination, the calves were treated with an antimicrobial - ending the study - after an outbreak of BRD caused a high incidence of disease in the non-vaccinated group. In conclusion, our results showed that Rispoval 4, a quadrivalent vaccine against respiratory viruses, under field conditions, reduces morbidity and mortality due to BRD in beef calves after weaning. 相似文献
3.
Sykes JE Bailiff NL Ball LM Foreman O George JW Fry MM 《Journal of the American Veterinary Medical Association》2004,224(12):1946-51, 1930-1
A 3-year-old sexually intact male Bull Mastiff underwent splenectomy for splenic thrombosis; prior to and after splenectomy, multiple blood transfusions were administered. Two weeks after the procedure, T-cell lymphoproliferative disease was diagnosed. Treatment with prednisone and chlorambucil was initiated, and 2 weeks later, cytologic examination of a blood smear revealed small (0.3 microm), coccoid basophilic bodies on the surface of approximately 70% of the RBCs. Morphologically, these resembled "Candidatus Mycoplasma haemominutum." A polymerase chain reaction assay was used to amplify a partial 16S rRNA sequence in blood obtained from the dog; the product was sequenced and compared with 16S rRNA gene sequences of other hemotropic mycoplasmas. The sequence was 98% homologous to that of "Candidatus M haemominutum", but only 77% homologous to that of M haemocanis and M haemofelis. 相似文献
4.
The study was designed to evaluate the anticoccidial activity of the methanolic extract of Musa paradisiaca root in chickens. The chickens were divided into six groups of 12 chickens each. Each chicken in five groups was infected
with 8,000 infective coccidia (Eimeria tenella) oocysts at day 28 of age while one group served as uninfected control. At day 7 post-infection, two chickens remaining in
each group were sacrificed for postmortem examination to confirm coccidiosis. Also at day 7 post-infection, each chicken in
four infected groups was given graded doses (250, 500 and 1,000 mg/kg b.w.) of the extract or amprolium (conventional drug).
Two groups (an infected and uninfected group) did not receive treatment. Parameters used to assess progress of infection and
response to treatment included clinical signs typical of coccidiosis, oocyst count per gramme of faeces (OPG) and packed cell
volume (PCV). Treatment of previously infected chickens with M. paradisiaca root extract resulted in a progressive decrease in severity of observed clinical signs, marked reductions in OPG and a gradual
increase in PCV. In each case, the changes were dose dependent. There was no significant difference in mean OPG and mean PCV
of the extract (at 1,000 mg/kg b.w.) and amprolium-treated groups at termination of the study (at day 50 of age). In the acute
toxicity study, the extract was found to be non-toxic to the chickens even at the highest dose of 4,000 mg/kg b.w. The results
of this study demonstrated that the extract has anticoccidial activity in a dose-dependent manner and at a dosage of 1,000 mg/kg
b.w. had similar efficacy with amprolium in the treatment of chicken coccidiosis. 相似文献
5.
6.
C. Renee Andrea DVM Lisle W. George DVM PhD Diplomate ACVIM 《Veterinary surgery : VS》1999,28(5):311-314
OBJECTIVE: To report surgical correction of hypertrophic periocular fat pads that cause loss of vision and behavioral changes in pot-bellied pigs. STUDY DESIGN: A retrospective study. ANIMALS OR SAMPLE POPULATION: Nine Vietnamese pot-bellied pigs. METHODS: Medical records of nine pot-bellied pigs admitted between 1994 and 1997 for loss of vision associated with hypertrophied periocular fat accumulations were reviewed. Outcome was assessed by contacting owners 4 months to 5 years after surgery. RESULTS: The most common clinical signs were related to impaired vision and included periocular dermatitis, lethargy, and aggressive behavior. Surgical removal of redundant periorbital fat and skin resulted in marked improvement in vision and behavior in all pigs. Overall client satisfaction was excellent. 相似文献
7.
8.
Rebecca Manley Andrea R. Matthews Federica Morandi George A. Henry Katherine H. DeAnna Gordon Conklin Ann Reed 《Veterinary radiology & ultrasound》2013,54(3):253-262
Motion artifact is an important limiting factor for abdominal magnetic resonance imaging (MRI) in veterinary patients. The purpose of this study was to determine the effects of pulse sequence on abdominal MRI diagnostic quality in dogs. Ten normal dogs were each scanned using 16 MRI pulse sequences. Sequences included breath‐holding sequences, respiratory navigation sequences, and traditional spin‐echo sequences. Four observers independently scored diagnostic quality for each sequence based on the appearance of specific organs, overall diagnostic quality, and degree of artifactual interference. Signal‐to‐noise ratio and contrast‐to‐noise ratio were also calculated for each sequence. The sequence with the highest overall mean diagnostic quality score was the dorsal T2 turbo spin echo (TSE) with fat saturation and breath‐holding. The sequence with the lowest mean diagnostic quality score was the dorsal T2 fast spin echo. The sequence with the highest signal‐to‐noise ratio for all evaluated organs was the sagittal T1 spin echo. Signal‐to‐noise and contrast‐to‐noise ratios did not correlate with subjective assessment of overall diagnostic quality for the majority of the sequences evaluated (P < 0.05). The three sequences considered to have the highest diagnostic quality for the cranial abdomen were the dorsal T2 TSE with fat saturation and breath‐hold, transverse T1 turbo fast low‐angle shot gradient echo with breath‐hold, and dorsal T2 half‐Fourier acquisition single shot TSE with respiratory navigation. These sequences had short acquisition times, yielded studies of similar diagnostic quality, provided complementary information, and are therefore recommended for routine canine abdominal MRI protocols. 相似文献
9.
Burkholder WJ Lees GE LeBlanc AK Slater MR Bauer JE Kashtan CE McCracken BA Hannah SS 《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》2004,18(2):165-175
Young adult heterozygous (carrier) female dogs with X-linked hereditary nephropathy (XLHN) have glomerular proteinuria but are otherwise healthy. Because data regarding dietary influences on the magnitude of proteinuria in dogs with spontaneous glomerular disease are not available, 12 such dogs were studied in a double crossover experiment intended to determine effects of altering dietary protein intake for up to 6 weeks. Dogs were blocked by urine protein : creatinine ratio (UPC) and randomly assigned to receive 2 diets: high protein (34.6% dry matter [DM], HP) or low protein (14.1% DM, LP) fed in HP-LP-HP or LP-HP-LP sequence. Food intake was measured daily, body weight (BW) was measured twice weekly, and UPC, plasma creatinine, blood urea nitrogen, phosphorus, albumin, and protein concentrations were measured at 2-week intervals. Nutrient digestibility was measured during the third treatment period. Diet had a significant effect (P < .0001) on all measured variables except plasma phosphorus (P > .5), but unintended differences in digestibility of protein and energy (P < or = .01) prevented assignment of the diet effect exclusively to protein. Proteinuria was greater (UPC 4.7 +/- 2.2 versus 1.8 +/- 1.1, P < .0001) when the HP diet was fed, but the LP diet did not maintain starting BW or plasma albumin concentration within the normal reference range. Diet greatly affects the magnitude of proteinuria in XLHN carrier females. Dietary protein restriction can reduce proteinuria in dogs with glomerular disease, but BW and blood protein concentrations may not be maintained if the restriction is too severe. 相似文献
10.
Polizopoulou ZS Kazakos G Patsikas MN Roubies N 《Journal of Feline Medicine and Surgery》2005,7(6):363-368
A case of hypervitaminosis A with secondary entrapment and compression of the left brachial plexus nerve roots is described. A 9-year-old male castrated domestic shorthair, fed a home-made diet based on raw pork liver, was submitted for examination for a left forelimb lameness that evolved to paralysis over a 2-month period. Clinical examination revealed a flaccid paralysis and atrophy of all left forelimb muscles. An ipsilateral Horner's syndrome was also noted. Radiological examination of the cervical and thoracic spine showed massive new bone formation at the ventral aspect of the second cervical to sixth thoracic vertebra. The diagnosis of hypervitaminosis A was made, based on the clinical and radiographic findings, as well as the determination of serum vitamin A concentration, which was 630 microg/dl, three times above the upper normal limit for this species. Despite the unfavourable initial prognosis, the cat progressively regained function of the affected limb approximately 6 months after the diet was changed to a commercial canned food. 相似文献