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   109篇
  免费   20篇
林业   3篇
  11篇
综合类   13篇
农作物   14篇
畜牧兽医   75篇
植物保护   13篇
  2023年   1篇
  2022年   2篇
  2021年   2篇
  2020年   1篇
  2019年   1篇
  2018年   3篇
  2017年   6篇
  2016年   4篇
  2015年   4篇
  2014年   5篇
  2013年   11篇
  2012年   2篇
  2011年   10篇
  2010年   4篇
  2009年   5篇
  2008年   2篇
  2007年   4篇
  2006年   6篇
  2005年   7篇
  2004年   5篇
  2003年   1篇
  2002年   1篇
  2001年   6篇
  2000年   1篇
  1999年   3篇
  1998年   2篇
  1997年   2篇
  1996年   1篇
  1995年   1篇
  1994年   1篇
  1990年   2篇
  1988年   2篇
  1986年   1篇
  1985年   3篇
  1984年   2篇
  1983年   1篇
  1982年   3篇
  1980年   1篇
  1979年   1篇
  1977年   1篇
  1975年   1篇
  1972年   1篇
  1969年   1篇
  1968年   1篇
  1892年   1篇
  1891年   1篇
  1885年   1篇
  1884年   1篇
排序方式: 共有129条查询结果,搜索用时 15 毫秒
71.
NorValley is a multi-purpose, high-yielding, whiteskinned cultivar suitable for processing into chips, dehydrated flakes, or for table stock use. It chips directly from long-term storage at 6 C without reconditioning. NorValley has wide adaptability and is suitable for production on irrigated or non-irrigated land and has a low incidence of hollow heart. NorValley was released by the North Dakota Agricultural Experiment Station on August 22,1996.  相似文献   
72.
生活在此处     
当邦妮和汉密尔顿·潘思打算为即将开始的婚姻生活寻找一个新家时,他们对未来并没有任何详细的规划,这个全新的温馨家园是由梅勒妮为他们设计的。现在,这对夫妇和11个月大的双胞胎女儿一起生活在伯明翰乡村的小别墅里,庭前碧树小径,一派悠然自得的田园风情。  相似文献   
73.
Manganese (Mn) is a trace element present in forages and cereals, and its concentration depends on soil status. Manganese deficiency in cattle, goats and ewes not only impairs oestrous cycle but reduces calf birth weight. The achievement of the first oestrus is delayed, and more attempts are necessary to obtain a successful conception. This study was conducted to investigate the effect of the availability of supplemental Mn during IVM on DNA damage of cumulus cells and total glutathione (GSH) content in oocytes and cumulus cells. The effect of supplementary Mn during IVM on subsequent embryo development was also studied. The results reported here indicate (i) DNA damage in cumulus cells decreased with 0, 2, 5 and 6 ng/ml Mn supplementation during IVM (p < 0.05). (ii) Intracellular GSH‐GSSG content increased (p < 0.01) with different Mn concentrations in oocytes and cumulus cells. Also, cumulus cell number per cumulus oocyte‐complexes (COC) did not differ either before or after IVM. (iii) Addition of Mn to maturation medium resulted in similar cleavage rates (p > 0.05) at 0, 2, 5 and 6 ng/ml Mn. However, subsequent embryo development to blastocyst stage was significantly higher (p < 0.01) in oocytes matured with 5 and 6 ng/ml Mn. (iv) There was also an increase (p < 0.05) in mean cell number per blastocyst obtained from oocytes matured with 5 and 6 ng/ml respect to zero Mn (IVM alone) and 2 ng/ml Mn. This study provides evidence that optimal embryo development to the blastocyst stage was partially dependent on the presence of Mn during IVM. Moreover, the availability of Mn during oocyte maturation ensures ‘normal’ intracellular GSH content in COCs and protects DNA integrity of cumulus cells.  相似文献   
74.
OBJECTIVE: To examine the effect of various clinical tracks within the veterinary medical clinical curriculum at Texas A&M University on clinical diagnostic proficiency as determined by pre- and post-training assessment. We expected that the clinical track chosen by the student would impact their measured outcome with bias toward higher scores in their chosen field. DESIGN: Prospective cohort study. STUDY POPULATION: 32 students from the College of Veterinary Medicine and Biomedical Sciences at Texas A&M University. PROCEDURES: By use of standardized, written case scenarios, clinical reasoning was assessed twice: once prior to the clinical (fourth) year of the curriculum and again at completion of the clinical year. Students demonstrated their abilities to collect and organize appropriate clinical data (history, physical examination, and laboratory findings), determine clinical diagnoses, and formulate and implement acceptable treatment modalities. Data from clinical assessments were compared for a given cohort and correlated with other measures (eg, grades, standardized test scores, and species-specific curricular track). RESULTS: Differences were detected in clinical diagnostic proficiency among students in different clinical tracks and for different species groups in the case scenarios. Tracking by species group in the clinical veterinary curriculum appeared to affect development of clinical reasoning and resulted in differential proficiency among cases for differing species groups. CONCLUSIONS AND CLINICAL RELEVANCE: Differences in clinical experiences between small animal tracks and all other track opportunities (large animal, mixed animal, and alternative) influenced the development of clinical proficiency in fourth-year veterinary students during their clinical training period.  相似文献   
75.
The aim of this study was to investigate the influence of zinc (Zn) on the health of cumulus–oocyte complex (COC) during in vitro maturation (IVM). Experiments were designed to evaluate the effect of Zn added to IVM medium on: DNA integrity, apoptosis, cumulus expansion and superoxide dismutase (SOD) activity of cumulus cells (CC). Also, role of CC on Zn transport during IVM was evaluated on oocyte developmental capacity. DNA damage and early apoptosis were higher in CC matured with 0 μg/ml Zn compared with 0.7, 1.1 and 1.5 μg/ml Zn (p < 0.05). Cumulus expansion did not show differences in COC matured with or without Zn supplementation (p > 0.05). Superoxide dismutase activity was higher in COC matured with 1.5 μg/ml Zn than with 0 μg/ml Zn (p < 0.05). Cleavage and blastocyst rates were recorded after IVM in three maturation systems: intact COCs, denuded oocytes with cumulus cells monolayer (DO + CC) and denuded oocytes (DO). Cleavage rates were similar when COC, DO + CC or DO were matured with 1.5 μg/ml Zn compared with control group (p > 0.05). Blastocyst rates were significantly higher in COC than in DO + CC and DO with the addition of 1.5 μg/ml Zn during IVM (p < 0.01). Blastocyst quality was enhanced in COC and DO + CC compared with DO when Zn was added to IVM medium (p < 0.001). The results of this study indicate that Zn supplementation to IVM medium (i) decreased DNA damage and apoptosis in CC; (ii) increased SOD activity in CC; (iii) did not modify cumulus expansion and cleavage rates after in vitro fertilization; (iv) improved subsequent embryo development up to blastocyst stage; and (v) enhanced blastocyst quality when CC were present either in intact COC or in coculture during IVM.  相似文献   
76.
A new labdane-diterpene, viteagnusin I (1), together with 23 known phytoconstituents were isolated from the fruits of Vitex agnus-castus L, and their structures characterized by spectroscopic methods (NMR and MS). The known compounds include ten flavonoids, five terpenoids, three neolignans, and four phenolic compounds, as well as one glyceride. Biological evaluation identified apigenin, 3-methylkaempferol, luteolin, and casticin as weak ligands of delta and mu opioid receptors, exhibiting dose-dependent receptor binding.  相似文献   
77.
Biosecurity risks are a major threat to the profitability of the industry as well as impacting human and animal health. Livestock producers play a crucial role in biosecurity as the first to notice changes in the health or productivity of their stock and are generally responsible for implementing protective measures. However, uptake of biosecurity measures by producers is variable. We critically appraised the current literature regarding biosecurity practices in Australian livestock industries and highlight aspects that are well understood as well as those where further research or information is needed. Findings from 12 cross-sectional studies suggest that Australian producers' knowledge of biosecurity methods and importance might have a positive influence on their willingness to implement or incorporate biosecurity practices. There is moderate evidence supportive of biosecurity being well understood by livestock producers across Australia. Barriers to producers using biosecurity practices included lack of information or communication from agricultural, veterinary or government organisations. It was found that larger stock numbers were positively correlated with biosecurity implementation and that producers used veterinarians, government and industry agencies as resources for trusted information.  相似文献   
78.
On March 1, 1992, the North Dakota Agricultural Experiment Station announced the release of a new russet potato cultivar named Goldrush. Goldrush is an oblong, smooth, russet-skinned potato cultivar that has very white flesh, good culinary quality, resistance to hollow heart and is adapted for both the fresh and processing market.  相似文献   
79.
Russet Norkotah is a long, smooth, shallow-eyed, russet-skinned potato cultivar with wide adaptation. It has a smooth golden russet-skin and produces a high percent of medium sized U.S. No. 1 tubers that are good count-carton size.  相似文献   
80.
In this study, Babesia screening was conducted in 55 rodents and 160 tick samples collected from primary forests and an oil palm plantation in Sarawak, Malaysian Borneo. PCR targeting the 18S ribosomal DNA revealed the presence of Babesia spp. DNA detected in two questing male Haemaphysalis shimoga ticks collected from the oil palm plantation. Sequence analysis revealed that both sequences were identical and had 98.6% identity to a Babesia macropus sequence obtained from Eastern grey kangaroos (Macropus giganteus) in Australia. Phylogenetic tree revealed clustering with marsupial-associated Babesia spp. in the Babesia sensu stricto clade. Whether or not H. shimoga is the competent vector and the importance of the Babesia sp. detected in this study warrants more investigation.  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