首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   2254篇
  免费   403篇
  国内免费   55篇
农学   7篇
基础科学   2篇
综合类   140篇
农作物   1篇
水产渔业   3篇
畜牧兽医   2558篇
植物保护   1篇
  2024年   2篇
  2023年   112篇
  2022年   24篇
  2021年   127篇
  2020年   199篇
  2019年   206篇
  2018年   141篇
  2017年   134篇
  2016年   139篇
  2015年   171篇
  2014年   155篇
  2013年   114篇
  2012年   118篇
  2011年   92篇
  2010年   81篇
  2009年   83篇
  2008年   72篇
  2007年   96篇
  2006年   63篇
  2005年   59篇
  2004年   74篇
  2003年   60篇
  2002年   43篇
  2001年   47篇
  2000年   40篇
  1999年   34篇
  1998年   29篇
  1997年   21篇
  1996年   21篇
  1995年   17篇
  1994年   14篇
  1993年   20篇
  1992年   16篇
  1991年   8篇
  1990年   13篇
  1989年   13篇
  1988年   10篇
  1987年   9篇
  1986年   8篇
  1985年   6篇
  1984年   5篇
  1983年   2篇
  1982年   2篇
  1981年   3篇
  1980年   4篇
  1978年   2篇
  1977年   1篇
  1956年   2篇
排序方式: 共有2712条查询结果,搜索用时 343 毫秒
41.
Recent technological advances in the human food industry with respect to meat processing have decreased the availability of animal proteins to the pet food industry which typically formulates diets with an excess of animal protein. In the long term, this is not sustainable; thus, alternative protein sources need to be investigated. This study examined three canine diets, comparing a typical animal protein‐based diet (control) with two experimental diets where the animal protein was substituted in part with vegetable protein (formulated based either on total protein or amino acid content) using a broiler model. Each diet was fed to six cages each containing two birds from day 15, 18 cages in total (36 birds). Excreta were collected from days 19 to 21. On day 23, birds were euthanized and weighed, and their ileal digesta were collected and pooled for each cage. In addition, one leg per cage was collected for evaluation of muscle mass. Results showed no significant difference in animal performance (feed intake or live weight gain) or muscle to leg proportion across the diets. Birds fed the control diet and the diet balanced for amino acid content exhibited the greatest coefficients of apparent metabolizability for nitrogen (p < .001). Birds fed the diets that contained partial replacement of animal with vegetable protein generally had greater ileal digestibility of amino acids compared to birds fed the control (animal protein) diet. Analysis of excreta showed no dietary difference in terms of dry matter content; however, birds fed the diet balanced for total protein and the diet balanced for amino acid content had significantly greater excreta nitrogen than the control (= .038). Overall, the study suggests vegetable proteins when formulated based on amino acid content are a viable alternative to animal proteins in canine diets.  相似文献   
42.
43.
44.
Contrast enhanced ultrasound (CEUS) is useful to evaluate tissue perfusion in the kidney. In veterinary medicine, sedation or anesthesia may be required in uncooperative or panting patients. The aim of this study was to evaluate and compare the normal kidney perfusion patterns in conscious and anesthetized dogs using CEUS. Eight healthy beagles were used in this study. Scanning was performed in conscious dogs using manual restraint (conscious group), or under general anesthesia using tiletamine-zolazepam and medetomidine (TZM group) or medetomidine (M group). The contrast agent (Sonovue®) was administered as an IV bolus. The peak intensity (PI), time to peak enhancement from injection (TTP0) and the time to peak enhancement from the initial rise (TTPup), upslope, downslope and area under the curve (AUC) were analyzed. Compared to the cortical values in the conscious group, TTP0 was significantly delayed in the TZM group, and upslope, TTP0 and TTPup were significantly different in the M group. The AUCs in the TZM and M groups were not different from those in the conscious group. The upslope of renal medullary perfusion was significantly decreased in the TZM and M groups. TTP0 and TTPup were also significantly delayed in these groups. The AUC of the medulla was significantly decreased in the M group. Therefore, TZM is useful as an anesthetic protocol when performing CEUS, and the obtained data may serve as reference values in the evaluation of renal perfusion using CEUS in dogs under anesthesia.  相似文献   
45.
通过注射利血平复制犬脾虚证动物模型,观察犬临床体征、体重及部分血清指标变化情况,并研究针灸对脾虚犬体重及血清指标的影响。结果显示,实验犬出现脾虚证后,其体重显著低于空白对照组(P〈0.05),血清谷丙转氨酶(ALT)、谷草转氨酶(AST)活性与丙二醛(MDA)含量均显著增高(P〈0.05);血清超氧化物歧化酶(SOD)活性显著降低(P〈0.05)。经针灸治疗后,实验组犬各项指标均得到明显改善,与阳性对照组比较呈显著性差异(P〈0.05)。试验结果表明,皮下注射利血平复制犬脾虚证动物模型后,选用一定穴位进行针灸,对治疗犬脾虚证有明显疗效。  相似文献   
46.
Bacillus coagulans GBI-30, 6086 is a commercially available spore-forming non-toxigenic microorganism approved for use in dog foods with high resiliency to stresses associated with commercial manufacturing. The objectives of this research were to examine the effect of B. coagulans on stool quality, nutrient digestibility, and intestinal health markers in healthy adult dogs. Extruded diets containing graded levels of B. coagulans applied either to the base ration before extrusion or to the exterior of the kibble as a topical coating after extrusion were randomly assigned to 10 individually housed adult beagle dogs (7 castrated males and 3 spayed females) of similar age (5.75 ± 0.23 yr) and body weight (12.3 ± 1.5 kg). The study was designed as a 5 × 5 replicated Latin square with 16-d adaptation followed by 5-d total fecal collection for each period. Five dietary treatments were formulated to deliver a dose of 0-, 6-, 7-, 8-, and 9-log10 colony-forming units (CFU) per dog per day for the control (CON), extruded B. coagulans (PEX), and low, moderate, and high B. coagulans coating levels (PCL, PCM, and PCH), respectively. Food-grade TiO2 was added to all diets at a level of 0.4% to serve as an indigestible dietary marker for digestibility calculations. Data were analyzed using a mixed model through SAS (version 9.4, SAS Institute, Inc., Cary, NC) with treatment as a fixed effect and room (i.e., replicate), period, and dog(room) as random effects. Apparent total tract digestibility of organic matter, crude protein, crude fat, and gross energy calculated by the marker method were numerically greatest for dogs fed the 9-log10 dose treatment with increases (P < 0.05) observed in gross energy and organic matter digestibility compared with the negative control. No significant differences were observed in food intake, stool quality, fecal pH, fecal ammonia, fecal short-chain fatty acids, or branched-chain fatty acids for the extruded B. coagulans treatment (PEX) or the coated B. coagulans treatments (PCL, PCM, and PCH) compared with CON. These results suggest that B. coagulans has a favorable impact on nutrient digestibility and no apparent adverse effects when added to extruded diets at a daily intake level of up to 9-log10 CFU in healthy adult dogs.  相似文献   
47.
An 8-year-old neutered male Yorkshire Terrier dog presented with head pressing, vestibular ataxia, neck tenderness, and no oculocephalic reflex. A demarcated lesion in the pons was identified on MRI. The patient was tentatively diagnosed with a glioma and was treated with hydroxyurea plus imatinib and prednisolone. After 30 days of therapeutic treatment, the patient showed a clear improvement in neurological signs, which lasted for 1117 days. On day 569 after the initiation of treatment, 18F-fluorodeoxyglucose (FDG)-positron emission tomography (PET) was performed with no significant findings on visual analysis. The average and maximal standardized uptake values (SUVs) were 1.92 and 2.29, respectively. The tumor-to-normal-tissue (T/N) ratio was 0.97. The first evidence of clinical deterioration was noticed on day 1147. On day 1155, 3,4-dihydroxy-6-[18F]-fluoro-l-phenylalanine (18F-FDOPA)-PET was performed. High uptake of 18F-FDOPA was observed in the intracranial lesion. The mean and maximal SUVs of the tumor were 1.59 and 2.29, respectively. The T/N ratio was 2.22. The patient was euthanized on day 1155 and histopathologic evaluations confirmed glioma (astrocytoma). This case shows that chemotherapy with hydroxyurea plus imatinib may be considered in the treatment of canine glioma. Furthermore, this is the first case describing the application of 18F-FDG and 18F-FDOPA in a dog with glioma.  相似文献   
48.
49.
从疑似犬瘟热(CD)病犬的脏器中分离到1株病毒,经间接免疫荧光试验、RT-PCR鉴定、红细胞凝集试验和对不同动物致病性试验,证实该病毒为犬瘟热病毒(CDV)强毒株,命名为CDV YD株。对H基因序列的测定和分析表明,YD株H基因与国内强毒株更接近,核苷酸同源性为98.4%~99.7%,氨基酸同源性为97.8%~99.7%,而与疫苗株核苷酸同源性较远为91.2%~91.5%,氨基酸同源性为90.3%~91.2%。推导的H蛋白氨基酸序列中有9个潜在的N连接糖基化位点(N-X-S/T),可能与病毒体外复制和中和抗体有关,另外有12个保守的半胱氨酸(Cys)残基,对H蛋白二级结构起重要作用;根据H基因核苷酸序列绘制的进化树表明,CDV YD株属于国内流行基因型:Asia-1型。该研究为了解当前中国CDV流行变异情况和犬瘟热疫苗的研发提供了数据。  相似文献   
50.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号