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   115篇
  免费   8篇
  国内免费   1篇
林业   1篇
农学   4篇
基础科学   1篇
  11篇
综合类   20篇
农作物   5篇
水产渔业   10篇
畜牧兽医   62篇
园艺   1篇
植物保护   9篇
  2023年   1篇
  2021年   4篇
  2019年   5篇
  2018年   2篇
  2017年   3篇
  2016年   4篇
  2015年   2篇
  2014年   6篇
  2013年   9篇
  2012年   3篇
  2011年   5篇
  2010年   6篇
  2009年   1篇
  2008年   4篇
  2007年   3篇
  2006年   5篇
  2005年   2篇
  2004年   2篇
  2003年   2篇
  2002年   6篇
  2001年   1篇
  2000年   9篇
  1999年   1篇
  1998年   2篇
  1997年   3篇
  1996年   3篇
  1994年   1篇
  1993年   2篇
  1992年   3篇
  1991年   1篇
  1989年   3篇
  1988年   1篇
  1987年   3篇
  1986年   1篇
  1985年   4篇
  1984年   1篇
  1983年   2篇
  1981年   1篇
  1980年   1篇
  1968年   1篇
  1956年   1篇
  1954年   1篇
  1952年   1篇
  1944年   1篇
  1928年   1篇
排序方式: 共有124条查询结果,搜索用时 734 毫秒
101.
针对《现代养殖设施与设备》课程没有规范教材的现状,探索符合人才培养目标和规格、适应市场需求的特色应用型教材建设,为应用型人才培养提供知识载体。并通过进一步实践,为教材的修订完善明确了方向。  相似文献   
102.
In a 20‐yr‐old long‐term experiment, the impact of continuous application of organic manures and inorganic fertilizers on soil quality and the sustainability of finger millet production was conducted on two cropping systems: finger millet and finger millet–groundnut on an Alfisol of semi‐arid southern India. The study was conducted from 1992 to 2011 at the All India Coordinated Research Project for Dryland Agriculture, UAS, Bangalore, using a randomized block design. The treatments comprised of T1: control [no fertilizer and no farmyard manure (FYM) applied], T2: FYM 10 t/ha, T3: FYM 10 t/ha + 50% of recommended NPK (50:50:25 kg/ha), T4: FYM 10 t/ha + 100% of recommended NPK and T5: 100% recommended NPK. Comparison of long‐term yield data between treatments was used to calculate a ‘sustainability yield index’ (SYI), which was greatest for T4 (FYM 10 t/ha + 100% of recommended NPK), in both rotational (0.68) and monocropping (0.63) situations. Soil quality indices were determined using principal component analysis linear scoring functions. The key indicators which contributed to the soil quality index (SQI) under rotation were organic C; potentially available N; extractable P, K and S; exchangeable Ca and Mg; dehydrogenase activity and microbial biomass C and N. The largest SQI (7.29) was observed in T4 (FYM 10 t/ha + 100% NPK), and the smallest (3.70) SQI was for the control. Application of 10 t/ha FYM together with NPK (50:50:25 kg/ha) sustained a mean yield of 3884 kg/ha.  相似文献   
103.
Wild waterfowl and their habitats are the main reservoirs of influenza A virus (IAV) mainly during the breeding season and prior to migration. This study describes the molecular characterization of an IAV isolated from 240 water samples of a small wetland during non-breeding season of migratory wild ducks in the State of Mexico, Mexico. The results showed that the virus belongs to the H4N2 subtype and each of its eight segments of the viral genome has similarity to IAV isolated from ducks in North America. This study suggests that IAV can be isolated from small wetland during non-breeding season of migrating waterfowl.  相似文献   
104.
A 13‐year‐old Quarter Horse mare presented for evaluation of chronic intermittent colic. Following extensive diagnostics, abdominal radiographs revealed two round, radiopaque objects in the caudal abdomen. Palpation per rectum and transrectal ultrasonography of the reproductive tract confirmed that the round objects were uterine marbles. Dinoprost tromethamine (Lutalyse, 5 mg i.m. q. 24 h for 2 days) was administered to bring the mare into oestrus, and both uterine marbles were manually removed from the uterus following digital dilation of the relaxed cervix. Follow‐up with the owner 12 months after discharge revealed that the mare had shown no further signs of abdominal discomfort since having the uterine marbles removed. To the authors' knowledge, this is the first published report of chronic intermittent colic attributed to uterine marbles in a mare.  相似文献   
105.
Molecular sexing is a rapid and safe procedure for bird sex determination. Two universal methods based on the amplification of a chromo‐helicase‐DNA‐Binding 1 (CHD) gene region, located in both sexual chromosomes (Z and W), have been established. We found that molecular sexing of Oreophasis derbianus failed by using these two procedures. One of them is based on a restriction site located in CHD1W gene but absent in CHD1Z. The DdeI restriction site, used successfully to determine gender in several bird species, was found to be lost because of nucleotide change in O. derbianus. This change created a new restriction site, NlaIII, that was successfully applied for sexing this endangered bird.  相似文献   
106.
To estimate when, during stallions’ extra‐gonadal reserves (EGR) depletion period, sperm quality would reach its highest quality, six light breed sexually rested stallions were collected daily for 7 days to deplete EGR. On collection days 1, 3, 5, and 7, sperm output, total (TM) and progressive (PM) motility, morphology, and plasma membrane (PLM) integrity were evaluated. Sperm output decreased as EGR depletion advanced, stabilizing on days 5–7. Sperm motility (TM and PM) and morphology were not different during EGR depletion. Plasma membrane integrity improved from day 1 to 3; however, no further improvement observed on days 5 and 7. Sperm of sexually rested stallions reach the highest quality on day 3 of the EGR depletion period.  相似文献   
107.
This study aimed to establish a culture system that improves the in vitro development of caprine preantral follicles. In a first experiment, follicles were encapsulated as a single unit per bead and cultured singly or in groups or with five follicles in the same alginate (ALG) bead for 18 days. In a subsequent experiment, the “five follicles per bead” design was chosen to culture in ALG, fibrin–alginate (FA) or hyaluronate (HA) for 18 days. In a third experiment, we chose the five follicles per bead in FA to culture for 30 days. The culture set‐up of five follicles per ALG bead increased antrum formation and follicle diameter compared to the other culture designs (p < .05). Moreover, under this condition, 44.44% of the oocytes from in vitro cultured preantral follicles reached meiotic resumption. A significant increase of follicle diameter occurred in attachment system and FA (p < .05), but the ALG condition reached the highest among all groups on day 18 (p < .05). Follicles encapsulated in matrix produced more estradiol and progesterone than attachment system (p < .05). The expression of MMP‐9 mRNA was higher in FA than in other groups (p < .05) and similar to antral follicles from in vivo control (p > .05). Only FA group resulted in oocytes matured. After 30 days, oocytes from preantral follicles in vitro grown in FA developed to eight‐cell parthenotes. In conclusion, a culture system using FA supported the development of caprine preantral follicles cultured in group and included in the same bead of hydrogel, improving the oocyte maturation and producing parthenotes.  相似文献   
108.
109.
Three rice cultivars, IR712, M1–48 and E425 were grown in solution culture for 10 weeks in temperature controlled glasshouses at IRRI, Los Baños, Philippines. Treatments consisted of two Mn levels, 0.5 and 50 μg.cm‐3 and two temperature regimes, 35/27 and 20/20 (day/night) in °C. Dry matter and Mn concentrations were determined at 2‐week intervals. In a second experiment, the M1–48 cultivar was grown in solutions containing 0.5, 1, 40 and 80 μg.cm‐3 Mn at 35/27, 29/21 and 20/20 °C (day/night) temperatures.

It was concluded that rice is more sensitive to excess Mn under cool conditions and that the concentration of Mn in the tissue at which toxicity symptoms appear or growth is decreased depends on the age of the tissues and the environmental conditions under which the plant is growing. Growth of two‐day old seedlings exposed to excess Mn was decreased to a greater degree than was that of 2‐week old seedlings. It is suggested that in screening rice cultivars for tolerance to excess Mn the environmental conditions should be rather rigidly controlled.  相似文献   

110.
A Tritrichomonas foetus-specific 5' Taq nuclease assay using a 3' minor groove binder-DNA probe (TaqMan MGB) targeting conserved regions of the internal transcribed spacer-1 (ITS-1) was developed and compared to established diagnostic procedures. Specificity of the assay was evaluated using bovine venereal microflora and a range of related trichomonad species. Assay sensitivity was evaluated with log(10) dilutions of known numbers of cells, and compared to that for microscopy following culture (InPouch TF test kit) and the conventional TFR3-TFR4 PCR assay. The 5' Taq nuclease assay detected a single cell per assay from smegma or mucus which was 2500-fold or 250-fold more sensitive than microscopy following selective culture from smegma or mucus respectively, and 500-fold more sensitive than culture followed by conventional PCR assay. The sensitivity of the conventional PCR assay was comparable to the 5' Taq nuclease assay when testing purified DNA extracted from clinical specimens, whereas the 5' Taq nuclease assay sensitivity improved using crude cell lysates, which were not suitable as template for the conventional PCR assay. Urine was evaluated as a diagnostic specimen providing improved and equivalent levels of T. foetus detection in spiked urine by both microscopy following culture and direct 5' Taq nuclease detection, respectively, compared with smegma and mucus, however inconclusive results were obtained with urine samples from the field study. Diagnostic specimens (n=159) were collected from herds with culture positive animals and of the 14 animals positive by 5' Taq nuclease assay, 3 were confirmed by selective culture/microscopy detection (Fisher's exact test P<0.001). The 5' Taq nuclease assay described here demonstrated superior sensitivity to traditional culture/microscopy and offers advantages over the application of conventional PCR for the detection of T. foetus in clinical samples.  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