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   355篇
  免费   1篇
林业   5篇
农学   1篇
  18篇
综合类   21篇
农作物   8篇
水产渔业   33篇
畜牧兽医   244篇
植物保护   26篇
  2025年   1篇
  2024年   3篇
  2023年   4篇
  2022年   6篇
  2021年   6篇
  2020年   6篇
  2019年   5篇
  2018年   8篇
  2017年   4篇
  2016年   9篇
  2015年   9篇
  2014年   13篇
  2013年   13篇
  2012年   20篇
  2011年   21篇
  2010年   3篇
  2009年   9篇
  2008年   11篇
  2007年   21篇
  2006年   17篇
  2005年   25篇
  2004年   14篇
  2003年   17篇
  2002年   11篇
  2001年   13篇
  2000年   15篇
  1999年   9篇
  1998年   2篇
  1996年   4篇
  1995年   5篇
  1994年   3篇
  1992年   14篇
  1991年   2篇
  1990年   9篇
  1989年   4篇
  1988年   2篇
  1985年   1篇
  1984年   3篇
  1982年   2篇
  1980年   1篇
  1979年   1篇
  1975年   2篇
  1974年   3篇
  1973年   1篇
  1972年   2篇
  1968年   1篇
  1963年   1篇
排序方式: 共有356条查询结果,搜索用时 20 毫秒
41.
    
The temporal expression of estrogen receptor (ER)-α and ER-β mRNA was examined in male Japanese quails. Femurs of quails receiving 17β-estradiol underwent RTPCR and histochemical analysis 1 to 15 days after treatment. Untreated quails were used as controls (day 0). Between days 0 and 5, cells lining the bone endosteal surface differentiated into osteoblasts, which in turn formed medullary bone. Expression of ER-α was already observed on day 0 and increased slightly during bone formation whereas ER-β was hardly detected throughout this process. After osteoclasts appeared on the medullary bone surface, this type of bone disappeared from the bone marrow cavity (days 7~15). ER-α expression simultaneously decreased slightly and ER-β levels remained very low. These results suggest that estrogen activity mediated by ER-α not only affects medullary bone formation but also bone resorption.  相似文献   
42.
Interleukin 10 (IL-10) genes of Djungarian, Chinese, and Syrian hamsters were cloned. The clones of IL-10 consisted of 537 bp nucleotides and 178 amino acids in full length, and the nucleotide and amino acid sequences exhibited a high degree of homology with those of the mouse and human. Since the number and position of signal sequences, N-glycosylations and cysteine sites in the IL-10 amino acid sequences of the hamsters were the same as those of the mouse, we suggest that the IL-10 molecular structures of the hamster are closer to that of the mouse than human.  相似文献   
43.
44.
    
The prevalence of faecal carriage of salmonella in 5393 pigs reared on 218 pig farms located in 31 of 47 prefectures in Japan over the period July 2003 to June 2005 was investigated. We isolated 172 strains belonging to 20 serovars and one untypable Salmonella enterica from 169 pig faecal samples (3.1%) collected from 48 farms (22.0%). The most prevalent type of S. enterica was untypable O4,12:d:- which lacks phase 2 flagellar antigen, representing 29.1% (50/172) of all isolates. Of 26 S. enterica serovar Typhimurium isolates, 16 strains appeared to be definitive phage type 104 (DT104) by polymerase chain reaction.  相似文献   
45.
    
Hypothermia during anesthetic events is a common adverse effect of anesthesia in laboratory animals. In particular, small rodents such as mice is susceptible to hypothermia during anesthetic events. Therefore, the animals will need additional thermal support by external heating devices during and after anesthesia. In general, the time of recovery from anesthesia is typically longer in case of injectable anesthesia rather than inhalant anesthesia. However, the durations of thermal support have been almost limited to 1 hr from administration of anesthesia in general. Our study objectives are two-fold: 1) to compare the levels of hypothermia induced by injectable anesthesia with medetomidine-midazolam-butorphanol (MMB) and inhalant anesthesia with isoflurane (ISO); 2) to find the adequate durations of thermal support for preventing hypothermia induced by their anesthesia in mice. Adult male ICR mice were anesthetized during 40 min without and with the thermal support for 1 (both anesthetic groups), 2, 3, and 5 hr (in MMB group). Without thermal support, the decrease of body temperature in MMB group were more severe than that in ISO group. The durations of thermal support completely prevented hypothermia at 5 hr-support in MMB group and that at 1 hr-support in ISO group. However, the other short durations did not prevent hypothermia at 1, 2 and 3 hr-support in MMB group. These results suggest that the mice should be received thermal support over 5 hr after injection of MMB anesthesia to prevent hypothermia.  相似文献   
46.
Cloning of the canine yes oncogene was attempted from a c library derived from a healthy canine spleen using a human c-yes-1 probe. The nucleotide and amino acid sequences revealed that the canine yes gene contained an open reading frame consisting of 539 amino acids. Its product had a molecular mass of 60,368 Daltons and showed 95·9 per cent and 90·4 per cent homology with human and chick p61c-yes, respectively. Moreover, the product had a myristylation signal, src homology region (SH) 3, SH2, and tyrosine kinase domains showing 98·8 per cent and 96·0 per cent homology with those of human beings and chickens, respectively. These findings indicate that the products of the canine yes gene may have non-receptor-type tyrosine kinase activity on the cell membrane, as is the case in human and chick p61c-yes  相似文献   
47.
    
Grazed pastures contribute significantly to the global nitrous oxide (N2O) budget. In grazed pastures, the highest N2O emission rates are often reported during winter when soils are wet. This review discusses the current knowledge about factors controlling winter N2O emissions in grazed pastures. High N2O emissions from pastures during winter are also observed from winter‐housed animal feeding systems. At near‐zero temperature, N2O producing microbial activity is limited but some soil microbial communities adjust to low temperature better than others. Soil microbiological studies focusing on the identification of cold‐tolerant denitrifiers and/or changes in microbial community structures under cold conditions are required. In winter‐grazed pastures, the availability of substrates, such as nitrate () and labile organic carbon (C), for soil microbes producing N2O is influenced by factors such as animal wintering system, effluent management systems and plant activity. When animals are housed, N2O emissions during the winter storage of manures and the emissions after their application are important contributors to N2O inventories. The activity of pasture during winter and its relationship to N2O emissions requires further study in order to understand the competition between plants and N2O producing microbes for nitrogen, and the role of root exudation. Additionally, the effect of low temperatures on nutrient availability under urine patches is still not well known. The reduction of N2O to dinitrogen is regulated by an enzyme N2O reductase and its encoding gene (nosZ) expression needs to be studied in more detail to investigate the mechanisms behind winter N2O emissions. To mitigate N2O emissions during winter, restricted grazing regimes and the use of nitrification inhibitors have been studied; however, little is known about the effectiveness of these methods in mitigating N2O emissions during freeze/thaw cycles and during periods of snow‐cover.  相似文献   
48.
Medical records of dogs with colorectal polyps were retrospectively reviewed, and clinical presentation of inflammatory colorectal polyps in miniature dachshunds was evaluated. Of 33 dogs found to have colorectal polyps, miniature dachshunds were markedly over-represented with 16 dogs (48%), of which 12 (75%) were found to have inflammatory polyps. Multiple polyps localized between the rectum and the descending colon was the most common finding in miniature dachshunds with inflammatory polyps. Twenty dogs (80%) out of 25 miniature dachshunds with inflammatory colorectal polyps responded to immunosuppressive therapy using prednisolone and cyclosporine. The results of this study indicate that miniature dachshunds are predisposed to develop inflammatory colorectal multiple polyps, for which immunosuppressive therapy may be a treatment option.  相似文献   
49.
50.
GM2 gangliosidosis variant 0 (human Sandhoff disease) is a lysosomal storage disease caused by simultaneous deficiencies of acid beta-hexosaminidase (Hex) A and Hex B due to an abnormality of beta-subunit, a common component in these enzyme molecules, which is coded by the HEXB gene. In the present study, a retrospective diagnosis was performed in 2 previous suspected cases of feline Sandhoff-like disease using a DNA test to detect the causative mutation identified previously in 4 cats in 2 other families of Japanese domestic cats. Enzymic analysis was also performed using stored leukocytes and plasma collected from the subject families in order to investigate the usefulness of enzymic diagnosis and genotyping of carriers. The DNA test suggested that the 2 cases were homozygous recessive for the mutation. Consequently, 6 cats homozygous for the same mutation have been found in 4 separate locations of Japan, suggesting that this mutant allele may be spread widely in the Japanese domestic cat populations. In enzymic analysis, Hex A and Hex B activities in leukocytes and plasma measured using 4-methylumbelliferyl N-acetyl-beta-D-glucosaminide as a substrate were negligible in affected cats, compared with those in normal and carrier cats. However, there was a wide overlap in enzyme activity between normal and carrier cats. Therefore, it was concluded that enzymic analysis is useful for diagnosis of affected cats, but is not acceptable for genotyping of carriers.  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