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   364篇
  免费   10篇
林业   19篇
农学   5篇
基础科学   1篇
  58篇
综合类   22篇
农作物   13篇
水产渔业   48篇
畜牧兽医   195篇
植物保护   13篇
  2022年   2篇
  2021年   14篇
  2020年   7篇
  2019年   4篇
  2018年   4篇
  2017年   7篇
  2016年   12篇
  2015年   7篇
  2014年   6篇
  2013年   13篇
  2012年   3篇
  2011年   24篇
  2010年   7篇
  2009年   11篇
  2008年   23篇
  2007年   10篇
  2006年   29篇
  2005年   15篇
  2004年   21篇
  2003年   17篇
  2002年   14篇
  2001年   19篇
  2000年   16篇
  1999年   14篇
  1998年   1篇
  1997年   5篇
  1995年   1篇
  1994年   3篇
  1993年   1篇
  1992年   10篇
  1991年   11篇
  1990年   4篇
  1989年   6篇
  1988年   4篇
  1987年   7篇
  1986年   4篇
  1985年   6篇
  1984年   1篇
  1981年   1篇
  1979年   5篇
  1975年   1篇
  1973年   1篇
  1969年   1篇
  1967年   1篇
  1966年   1篇
排序方式: 共有374条查询结果,搜索用时 31 毫秒
101.
We examined early morphological changes in pancreatic endocrine cells within 12 h of intravenous streptozotocin (STZ) administration (60 mg/kg). Thirty rats were allocated either to a control group (vehicle alone) or to one of four experimental groups tested after 3, 6, 9 and 12 h. Karyopyknosis and cytoplasmic vacuoles were first observed in beta-cell cytoplasm 3 h after STZ administration (STZ-3 h), and the most severe damage was found in beta cells at STZ-12 h. Insulin-positive non-islet cells were observed near the intercalated duct (ICD) and/or centroacinar (CA) cells at STZ-6 h and their numbers peaked at STZ-6 h. The distribution patterns of the insulin-positive cells and those of nestin and insulin-like growth factor-1 were similar and their nuclei were positive for proliferating cell nuclear antigen. Thus, ICD cells and/or CA cells reacted immediately to transform into insulin-secreting cells to replace injured beta cells (or to compensate for the lack of beta cells) within 12 h of STZ administration.  相似文献   
102.
A 7-year-old intact female golden Retriever was referred for evaluation of an intraorbital mass of the left eye. Based on ophthalmoscopy, ultrasonography and magnetic resonance imaging (MRI), the tentative diagnosis was made as an intraocular neoplasia, especially choroidal melanoma. The orbital exenteration of the affected eye was performed. The mass was histologically diagnosed as malignant choroidal melanoma. No signs of recurrence and metastasis were detected by thoracic radiographs, blood examinations and MR images, and the dog was clinically healthy for 23 months after operation.  相似文献   
103.
Nasal swabs of 293 calves were examined for Mycoplasma. The samples were collected from calves affected with respiratory diseases on 71 farms in various parts of Japan between 1996 and 1997. Mycoplasma bovirhinis was isolated from 47 of 293 calves (16.0%). Mycoplasma alkalescens, M. bovis, M. arginini, M. bovigenitalium and Acholeplasma spp. were isolated from 19 (6.5%), seven (2.4%), four (1.4%), four (1.4%) and 18 (6.1%) calves, respectively. Pasteurella multocida and P. haemolytica were isolated from 60% of Mycoplasma-positive calves. However, other bacteria were not isolated from calves. To evaluate the antimicrobial susceptibility of their isolates, 68 M. bovirhinis, 21 M. alkalescens and 10 M. bovis strains were examined for 12 antimicrobial agents. All isolates showed higher susceptibility to tiamulin than to the other drugs used in the study. However, erythromycin had no effect on any of the Mycoplasma strains studied. The field isolates were less susceptible than the type strains to some drugs, such as spiramycin, oxytetracycline and tylosin.  相似文献   
104.
OBJECTIVE: To determine whether small intestinal ischemia and reperfusion induces bacterial translocation and proinflammatory cytokine response in either the systemic or portal circulation in dogs. ANIMALS: 17 healthy adult Beagles. PROCEDURE: The superior mesenteric artery (SMA) was occluded for 0 (group-3 dogs), 30 (group-1 dogs), or 60 (group-2 dogs) minutes, followed by reperfusion for 180 minutes; serum lactate and endotoxin concentrations and tumor necrosis factor-alpha (TNF-alpha), interleukin-1beta (IL-1beta), and IL-6 activities in the systemic and portal circulation and intramucosal pH were measured at various time points. RESULTS: In group-2 dogs, TNFalpha activity was found to be significantly increased in the portal circulation, peaking at 60 minutes of reperfusion; TNF-alpha activity, in the systemic circulation, gradually increased from 60 minutes of reperfusion to the end of the experiment; however, the increase was not significant. In group-1 and -2 dogs, IL-6 activities significantly and gradually increased in the systemic and portal circulation during the reperfusion phase, and the magnitude of these increases was dependent on the duration of the ischemic phase. There were no significant changes in IL-1beta activity or endotoxin concentration in any dog group. CONCLUSIONS AND CLINICAL RELEVANCE: Results of the our study indicate that intestinal ischemia and reperfusion leads to significant increases of the circulating TNF-alpha and IL-6 activities, depending on the duration of the ischemia phase, in the absence of detectable endotoxin in the circulation. This finding suggests that intestinal ischemia and reperfusion induces a systemic proinflammatory cytokine response in dogs.  相似文献   
105.
To study the effect of estrogenic chemicals on fish, the gonadosomatic index (GSI = [testis weight/body weight] x 100) and testis histology of mature common carp (Cyprinus carpio) from 2 contaminated sites (Ishizu and Wada rivers, Osaka) and a control site were examined between June 1998 and March 2001. The concentration of nonylphenol, bisphenol A and 17beta-estradiol in the Ishizu river was 3-4 times higher than in the Wada river. In the pre-breeding and breeding seasons, there were no significant differences in body weight among carp from the 3 sites, the body weight of Ishizu river carp being significantly lower (p<0.05) than that of Wada river fish only in the post-breeding season. The GSI and testis weight in fish from the Ishizu river were significantly lower (p<0.05) than in control fish during all phases of gonadal cycle and lower than in Wada river fish in the pre-breeding and post-breeding season. No histological abnormalities were found in the testes of the males examined. Histological observation of the testes revealed a delay in the onset of spermatogenesis in fish from the Ishizu river compared with those from the other sites. These results clearly imply that the estrogenic chemicals in the Ishizu river adversely affect the testis development of the fish.  相似文献   
106.
In 1996 and 1997, the seroprevalence against Leptospira in parturient sows with premature birth or stillbirth from two herds was investigated. In three out of four sow serum samples obtained in Gunma Prefecture, the antibody titers to Leptospira interrogans serovar copenhageni (M20) were higher than 10,000 (the reciprocal of the serum dilution). Furthermore, the antibody titers to L. interrogans serovar canicola (Hond Utrecht IV) were significantly high in the three sows and the titers ranged from 1,000 to 3,000. In sows obtained in Chiba Prefecture, significantly high antibody titers to serovar copenhageni (M20) were confirmed in eight out of 40 sows, and antibody titers greater than 10,000 in six of them. Significantly high antibody titers to L. interrogans serovar icterohaemorrhagiae (RGA) and L. canicola (Hond Utrecht IV) were confirmed in four and 18 out of the 40 sows, respectively, compared with the titers to the other serovars. These findings may indicate the prevalence of leptospirosis in pig herds in both Gunma and Chiba Prefectures.  相似文献   
107.
Activities of malate dehydrogenase (MDH) and aspartate aminotransferase in the malate-aspartate shuttle were significantly increased in the cytosolic fractions of livers with early neoplastic symptoms such as swelling and discoloration in transgenic mice carrying the prototype human c-Ha-ras gene, Tg-rasH2 mice, which were administered with diethylnitrosamine (DEN) as a carcinogenic chemical at a dose of 200 mg/kg body weight. Cytosolic MDH/LDH (lactate dehydrogenase) (ML) ratio increased significantly and was considered to be a useful marker to characterize the energy metabolism at early neoplastic stage in livers of the Tg-rasH2 mice.  相似文献   
108.
A female stillborn Holstein calf with shortened cervical and thoracic regions, protrusion of the tongue, and bilateral symmetric flexural contraction of the anterior limbs was delivered on gestation day 281. Multiple hemivertebrae, fused and misshaped vertebrae, synostosis and scoliosis of cervical, thoracic and lumbar vertebral column were found in the affected calf by radiographic and computed tomographic (CT) analysis. Ten pairs of ribs were present and the sternum consisted of 9 sternebrae. Multiple morphologic abnormalities including fusion, malformation, and displacement, were found in the ribs and sternum. Cardiac anomalies, including atrial septal defect and hypertrophy of right ventricle, were observed. DNA-polymerase chain reaction (PCR) analysis demonstrated that amplified product from the liver DNA of the affected calf had identical pattern to that associated with complex vertebral malformation (CVM) of Holstein calves and that her dam was a heterozygous carrier of CVM. The affected calf was diagnosed as having CVM based on the DNA-PCR results and the characteristic findings, and was recorded as a first documentation of CVM confirmed in a Holstein calf in Japan.  相似文献   
109.
110.
To eliminate the masking effect by flavonoid glycosides, which comprise approximately 70% of conventionally prepared sample, the readily extractable fraction from Citrus juice, which was prepared by adsorbing on HP-20 resin and eluting with ethanol and acetone from the resin, was subjected to antiproliferative tests against several cancer cell lines. Screening of 34 Citrus juices indicated that King (Citrus nobilis) strongly inhibited proliferation of all cancer cell lines examined. Sweet lime and Kabuchi inhibited three of the four cancer cell lines. In contrast, these samples were substantially less cytotoxic toward normal human cell lines.  相似文献   
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