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   64篇
  免费   8篇
林业   4篇
农学   1篇
基础科学   1篇
  8篇
综合类   18篇
农作物   3篇
水产渔业   9篇
畜牧兽医   28篇
  2023年   2篇
  2022年   1篇
  2021年   2篇
  2020年   3篇
  2019年   2篇
  2018年   1篇
  2017年   4篇
  2015年   2篇
  2012年   4篇
  2011年   1篇
  2010年   3篇
  2009年   2篇
  2008年   2篇
  2007年   4篇
  2006年   3篇
  2005年   1篇
  2004年   3篇
  2003年   2篇
  2002年   4篇
  2001年   1篇
  2000年   1篇
  1999年   1篇
  1995年   1篇
  1992年   1篇
  1991年   1篇
  1990年   3篇
  1989年   3篇
  1988年   1篇
  1987年   2篇
  1986年   1篇
  1985年   1篇
  1983年   1篇
  1977年   1篇
  1974年   1篇
  1973年   1篇
  1970年   1篇
  1969年   1篇
  1968年   1篇
  1967年   1篇
  1947年   1篇
排序方式: 共有72条查询结果,搜索用时 31 毫秒
51.
52.
53.
Starches from eight soft wheat samples (two parent lines and six offspring) were isolated; relationships between their structures and properties were examined. Branch chain‐length distributions of amylopectins were determined by using high‐performance anion exchange chromatography equipped with an amyloglucosidase reactor and a pulsed amperometric detector (HPAEC‐ENZ‐PAD). Results showed that the average chain length of the eight samples varied at DP 25.6–26.9. Starch samples of lines 02, 60, 63, 95, and 114 consisted of amylopectins with more long chains (DP ≥ 37) and longer average chain length (DP 26.2–26.9) than that of other samples. These starch samples of longer branch chain length displayed higher gelatinization temperatures (55.3–56.5°C) than that of other samples (54.4–54.9°C) and higher peak viscosity (110–131 RVU) and lower pasting temperature (86.3–87.6°C) than others (83–100 RVU and 88.2–88.9°C, respectively). The Mw of amylopectins, determined by using high‐performance size exclusion chromatography equipped with multiangle laser‐light scattering and refractive index detectors (HPSEC‐MALLS‐RI), were similar for all samples (6.17 × 108 to 6.97 × 108). There were no significant differences in amylose and phosphorus contents between samples. These results indicated that physical properties of wheat starch were affected by the branch‐chain length of amylopectin.  相似文献   
54.
Dredging can have significant impacts on aquatic environments, but the direct effects on fish have not been critically evaluated. Here, a meta‐analysis following a conservative approach is used to understand how dredging‐related stressors, including suspended sediment, contaminated sediment, hydraulic entrainment and underwater noise, directly influence the effect size and the response elicited in fish across all aquatic ecosystems and all life‐history stages. This is followed by an in‐depth review summarizing the effects of each dredging‐related stressor on fish. Across all dredging‐related stressors, studies that reported fish mortality had significantly higher effect sizes than those that describe physiological responses, although indicators of dredge impacts should endeavour to detect effects before excessive mortality occurs. Studies examining the effects of contaminated sediment also had significantly higher effect sizes than studies on clean sediment alone or noise, suggesting additive or synergistic impacts from dredging‐related stressors. The early life stages such as eggs and larvae were most likely to suffer lethal impacts, while behavioural effects were more likely to occur in adult catadromous fishes. Both suspended sediment concentration and duration of exposure greatly influenced the type of fish response observed, with both higher concentrations and longer exposure durations associated with fish mortality. The review highlights the need for in situ studies on the effects of dredging on fish which consider the interactive effects of multiple dredging‐related stressors and their impact on sensitive species of ecological and fisheries value. This information will improve the management of dredging projects and ultimately minimize their impacts on fish.  相似文献   
55.
Extended culture of mouse embryo cells without senescence: inhibition by serum   总被引:20,自引:0,他引:20  
Mouse embryo cells cultured in vitro in serum-supplemented media undergo growth crisis, resulting in the loss of genomically normal cells prior to the appearance of established, aneuploid cell lines. Mouse embryo cells established and maintained for multiple passages in the absence of serum did not exhibit growth crisis or gross chromosomal aberration. Cells cultured under these conditions were dependent on epidermal growth factor for survival. Proliferation was reversibly inhibited by serum or platelet-free plasma, suggesting that mouse embryo cultures maintained by conventional procedures are under the influence of inhibitory factors.  相似文献   
56.
Wood can be a good source of DNA for various applications in forensic forestry and timber trade if high-quality DNA can be retrieved from the dry wood. In order to provide a general guideline for DNA authenticity testing established for Neobalanocarpus heimii, this study was designed to evaluate the potential of extracting DNA from the dry wood. Overall, the efficacy of DNA extraction was higher for the cambium and sapwood than for the heartwood tissues. In terms of DNA extraction protocols, the Qiagen kit and CTAB with PTB protocol showed higher PCR amplification rates. In order to safeguard the intactness of the DNA, the DNA extraction from dry wood is recommended to be carried out within 6?weeks after felling for logs and 6?months after felling for stumps. The results also showed that the amplicon size might not account for the PCR amplification success rate, and chloroplast genome yielded higher amplification success rate compared with nuclear genome. However, only the chloroplast region can be perfectly retrieved from heat-treated lumber.  相似文献   
57.
Lymphoma is an important disease in dogs and people, with similar biological characteristics. We tested the binding affinity of a peptidomimetic LLP2A, previously shown to bind the alpha4-beta1 integrin on human lymphoma cell lines, to lymphocytes of dogs with spontaneously occurring lymphoma. Fine needle aspirates of lymph nodes from 32 dogs with B-cell lymphoma and 7 dogs with T-cell lymphoma were evaluated using flow cytometry. For B cells, the lowest MFI levels were in unlabeled, non-neoplastic lymphocytes. The highest median fluorescent intensity (MFI) levels occurred in LLP2A-labeled lymphoma cells from dogs that had not received chemotherapy followed by labeled lymphoma cells from dogs that had received chemotherapy. The fluorescence profile of the T-cell samples was similar although many of the differences were not statistically significant, likely due to low sample number. Specifically, LLP2A-labeled T-cell lymphoma cells had a significantly higher MFI compared to unlabeled non-neoplastic lymphocytes. LLP2A affinity was not significantly different in unlabeled and labeled T-cell lymphoma cells, and labeled non-neoplastic lymphocytes. For both B and T cells, labeling with LLP2A tended to increase MFI in both normal and lymphoma cells. Lymphoma cells had higher mean MFI levels than non-neoplastic lymphocytes, and chemotherapy acted to decrease MFI. In summary, these data demonstrate that LLP2A has affinity to canine lymphoma cells and indicates expression of the alpha4-beta1 integrin on these cells. In fact, LLP2A preferentially binds neoplastic B-cells, suggesting that this small molecule may be of use in cross-species clinical trials of targeted therapeutics.  相似文献   
58.
BACKGROUND: Diseases and abnormal physiologic conditions can alter the concentrations of enzymes, metabolites, minerals, and hormones in the blood of animals. The ringed seal (Pusa hispida) has been selected as a key species for environmental monitoring, but information on disease and health parameters for this species is scarce. OBJECTIVES: The aim of the study reported here was to obtain serum chemistry reference intervals for free-ranging ringed seals in Svalbard, and then to evaluate serum chemistry values in relation to age, body condition, and sex. METHODS: Blood samples were collected after death from ringed seals in Wijdefjorden and Billefjorden, Svalbard (2002-2003; n = 75). Serum was analyzed for 24 selected serum chemistry parameters (enzymes, protein, metabolites, minerals, and cortisol). RESULTS: Compared with younger or older animals, seals between 7 and 16 years of age had larger variations in the activities of alanine transaminase, aspartate transaminase, lactate dehydrogenase, and creatine kinase (CK). Animals classified as having low body condition status had more variation in the serum activity of these enzymes, compared with that in animals with higher condition scores. Serum cortisol concentration was higher in young animals (1-5 years) than in older animals. Serum CK activity was higher in males than in females. CONCLUSION: The data reported here may be useful in monitoring the health of ringed seals and for tracking the impact of environmental changes in the Arctic.  相似文献   
59.
60.
Toxicology is a vast subject. Animals are exposed to numerous drugs, household products, plants, chemicals, pesticides and venomous animals. In addition to the individual toxicity of the various potential poisons, there is also the question of individual response and, more importantly, of species differences in toxicity. This review serves to address some of the common questions asked when dealing with animals with possible poisoning, providing evidence where available. The role of emetics, activated charcoal and lipid infusion in the management of poisoning in animals, the toxic dose of chocolate, grapes and dried fruit in dogs, the use of antidotes in paracetamol poisoning, timing of antidotal therapy in ethylene glycol toxicosis and whether lilies are toxic to dogs are discussed.  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