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   318篇
  免费   7篇
  国内免费   11篇
林业   8篇
农学   10篇
基础科学   2篇
  32篇
综合类   29篇
农作物   9篇
水产渔业   43篇
畜牧兽医   169篇
园艺   5篇
植物保护   29篇
  2023年   3篇
  2021年   17篇
  2020年   3篇
  2017年   2篇
  2016年   5篇
  2015年   22篇
  2014年   20篇
  2013年   13篇
  2012年   6篇
  2011年   14篇
  2010年   19篇
  2009年   21篇
  2008年   13篇
  2007年   10篇
  2006年   19篇
  2005年   6篇
  2004年   9篇
  2003年   3篇
  2002年   9篇
  2001年   2篇
  1999年   2篇
  1998年   3篇
  1997年   6篇
  1996年   6篇
  1995年   2篇
  1994年   3篇
  1993年   6篇
  1991年   2篇
  1987年   2篇
  1985年   7篇
  1984年   2篇
  1982年   4篇
  1981年   4篇
  1980年   2篇
  1979年   3篇
  1977年   2篇
  1976年   5篇
  1975年   2篇
  1974年   2篇
  1973年   2篇
  1965年   3篇
  1963年   4篇
  1961年   2篇
  1959年   4篇
  1958年   5篇
  1957年   6篇
  1956年   5篇
  1955年   2篇
  1954年   5篇
  1948年   2篇
排序方式: 共有336条查询结果,搜索用时 15 毫秒
1.
To establish a protocol for a multi-phase computed tomography (CT) of the canine pancreas using the bolus-tracking technique, dynamic scan and multi-phase CT were performed in six normal beagle dogs. The dynamic scan was performed for 60 sec at 1-sec intervals after the injection (4 ml/sec) of a contrast medium, and intervals from aortic enhancement appearance to aortic, pancreatic parenchymal and portal vein peaks were measured. The multi-phase CT with 3 phases was performed three times using a bolus-tracking technique. Scan delays were 0, 15 and 30 in first multi-phase scan; 5, 20 and 35 in second multi-phase scan; and 10, 25 and 40 sec in third multi-phase scan, respectively. Attenuation values and contrast enhancement pattern were analyzed from the aorta, pancreas and portal vein. The intervals from aortic enhancement appearance to aortic, pancreatic parenchymal and portal vein peaks were 3.8 ± 0.7, 8.7 ± 0.9 and 13.3 ± 1.5 sec, respectively. The maximum attenuation values of the aorta, pancreatic parenchyma and portal vein were present at scan sections with no scan delay, a 5-sec delay and a 10-sec delay, respectively. When a multi-phase CT of the canine pancreas is triggered at aortic enhancement appearance using a bolus-tracking technique, the recommended optimal delay times of the arterial and pancreatic parenchymal phases are no scan delay and 5 sec, respectively.  相似文献   
2.
Mitochondria are highly dynamic organelles that undergo constant fusion/fission as well as activities orchestrated by large dynamin-related GTPases. These dynamic mitochondrial processes influence mitochondrial morphology, size and function. Therefore, this study was conducted to evaluate the effects of mitochondrial fission inhibitor, mdivi-1, on developmental competence and mitochondrial function of porcine embryos and primary cells. Presumptive porcine embryos were cultured in PZM-3 medium supplemented with mdivi-1 (0, 10 and 50 μM) for 6 days. Porcine fibroblast cells were cultured in growth medium with mdivi-1 (0 and 50 μM) for 2 days. Our results showed that the rate of blastocyst production and cell growth in the mdivi-1 (50 μM) treated group was lower than that of the control group (P < 0.05). Moreover, loss of mitochondrial membrane potential in the mdivi-1 (50 μM) treated group was increased relative to the control group (P < 0.05). Subsequent evaluation revealed that the intracellular levels of reactive oxygen species (ROS) and the apoptotic index were increased by mdivi-1 (50 μM) treatment (P < 0.05). Finally, the expression of mitochondrial fission-related protein (Drp 1) was lower in the embryos and cells in the mdivi-1-treated group than the control group. Taken together, these results indicate that mdivi-1 treatment may inhibit developmental competence and mitochondrial function in porcine embryos and primary cells.  相似文献   
3.
北极在许多人心中意味着遥远、寒冷和神秘,是一个冰天雪地的童话世界。然而,近年来气候变暖和油气田开发对北极带来了很大冲击,当地特有的景观、传统和生活方式随着冰雪的消融在慢慢发生变化。  相似文献   
4.
This study were carried out in the Experimental Forest (37( 48' 10" N, 127( 48' 50" E) of Gangwon Forest Development Institute, Gamjeong-ri, Chuncheon, Gangwon-do Province, Korea from Dec. 1999 to Jul. 2002. Eight individuals (three males and five females) of hazel grouse were captured and they were marked with a 14-g necklace-type transmitter. The surveying results showed that females were more active than males throughout the year, but males were more mobile than females in spring. The degree of movement for females and males was similar from summer to winter. The overlap degree of habitat was very large from spring to autumn. Hazel grouse had greater shifts in area use in winter. They used similar area from spring to autumn, made a shift in their habitat use in winter, and then shifted back to the previous habitat.  相似文献   
5.
To understand wood colonization by sapstain fungi and their potential biocontrol agents, it is necessary to differentiate these organisms directly on their natural substrates. In the present study the feasibility of transforming with the green fluorescent protein (GFP), the sapstain fungus Ophiostoma piceae and a potential biocontrol agent Cartapip®, an Ophiostoma piliferum albino strain was assessed. Transformants of the two fungal species were screened by polymerase chain reaction and Southern blot analyses. The GFP was expressed in spores, synnemata and mycelia of the transformants grown in artificial media or wood. The growth, pigmentation and wood colonization of the transformants were similar to that of the non‐transformants, suggesting that the presence of the gfp gene had no negative effect on the biology of the transformants. Using fluorescence and confocal microscopy, the GFP‐expressing fungi were easily differentiated from the wild‐type strains and other fungal species in wood, even 4 months after inoculation. The results show that the use of the GFP system is feasible to monitor Ophiostoma fungi in wood.  相似文献   
6.
Contrast enhanced ultrasound (CEUS) is useful to evaluate tissue perfusion in the kidney. In veterinary medicine, sedation or anesthesia may be required in uncooperative or panting patients. The aim of this study was to evaluate and compare the normal kidney perfusion patterns in conscious and anesthetized dogs using CEUS. Eight healthy beagles were used in this study. Scanning was performed in conscious dogs using manual restraint (conscious group), or under general anesthesia using tiletamine-zolazepam and medetomidine (TZM group) or medetomidine (M group). The contrast agent (Sonovue®) was administered as an IV bolus. The peak intensity (PI), time to peak enhancement from injection (TTP0) and the time to peak enhancement from the initial rise (TTPup), upslope, downslope and area under the curve (AUC) were analyzed. Compared to the cortical values in the conscious group, TTP0 was significantly delayed in the TZM group, and upslope, TTP0 and TTPup were significantly different in the M group. The AUCs in the TZM and M groups were not different from those in the conscious group. The upslope of renal medullary perfusion was significantly decreased in the TZM and M groups. TTP0 and TTPup were also significantly delayed in these groups. The AUC of the medulla was significantly decreased in the M group. Therefore, TZM is useful as an anesthetic protocol when performing CEUS, and the obtained data may serve as reference values in the evaluation of renal perfusion using CEUS in dogs under anesthesia.  相似文献   
7.
Phenylbutazone (PBZ) is a nonsteroidal anti‐inflammatory drug used in the treatment of chronic pain and arthritis. Topical and transdermal administration of PBZ would be beneficial in large animals in terms of minimizing gastro‐intestinal ulcerations and other side effects, easy administration to legs and joints and minimizing the dose to reduce systemic toxicity of the drug. A topical liposomal preparation with different concentrations of a mono‐substituted alkyl amide (MSA) and PBZ was formulated. The formulations were evaluated by in vitro skin‐permeation kinetics through deer skin using Franz diffusion cells. By increasing drug loading from 1% to 5% w/w, the steady‐state flux (μg/cm2/h) of PBZ was increased twofold (P < 0.001). Similarly, by increasing the MSA concentration from 0% to 4%, the steady‐state flux (μg/cm2/h) of PBZ was increased twofold (P < 0.001). Overall, by increasing the drug load and the use of an appropriate amount of the penetration enhancer, the steady‐state flux of PBZ through skin was increased fourfold (P < 0.001). MSA at both 2% and 4% w/w concentrations significantly increased the skin levels of PBZ as compared with control (P < 0.05). In conclusion, MSA served as an effective skin‐penetration enhancer in the liposomal gel of PBZ for deer.  相似文献   
8.
Objective— To (1) report a technique for repair of feline ilial fractures using a dorsally applied bone plate and (2) compare outcome with cats treated by a lateral plate.
Study Design— Prospective study.
Animals— Cats (n=10) with iliac fractures.
Methods— Cats with ilial fractures (January 2005–December 2006) were treated by application of a dorsally applied bone plate. Immediate postoperative radiographs were compared with those taken 4–6 weeks later to assess screw loosening, screw purchase, and pelvic canal narrowing. Owners were contacted for medium-term (>3 month) follow-up. Data were compared with a report of outcome after lateral plating (LP) in 21 cats.
Results— Mean (± SD) screw purchase (89 ± 11 mm) was significantly greater ( P <.01) with a dorsal plate compared with a lateral plate (33 ± 8 mm). Significantly more screws ( P <.01) were used with a dorsal plate (median, 7) compared with a lateral plate (median, 6). Significantly less postoperative pelvic canal narrowing developed in the dorsal plating group between postoperative and 4–6-week follow-up radiography compared with the LP group (2% versus 15%, P <.01).
Conclusion— Dorsal plating of feline ilial fractures results in significantly less screw loosening and pelvic canal narrowing at 4–6 weeks after surgery compared with LP.
Clinical Relevance— Dorsal plating of feline iliac fractures may reduce complications associated with pelvic canal narrowing such as constipation and megacolon.  相似文献   
9.
The objective of the present study was to investigate the effect of fermented apple diet (FAD) supplementation on the growth performance and meat quality in finishing Berkshires. The FAD was made from dropped apple mixed with rice bran and barley bran. Until 81 ± 1 kg live weight at 133 ± 1 days, the animals were fed a growing diet, after which experimental samples were fixed at 0, 2, 4 and 6% FAD as C, T1, T2 and T3 in the finishing diets. Growth performance, ADG, ADFI and feed efficiency were improved in T1 than other groups. In carcass parameters, carcass weight was higher ( P  < 0.05) in T1 than in other groups. In meat quality, moisture and crude protein contents decreased ( P  < 0.05) by addition of FAD. pH24 and WHC were higher ( P  < 0.05) in T1 than other groups. In sensory evaluation, marbling of fresh meat and tenderness, juiciness, flavor and overall acceptability of cooked meat were improved by the addition of FAD. According to the results of our experiment, FAD can be used for improvement of meat quality parameters.  相似文献   
10.
链霉菌FR-008产生一种七烯大环内酯类抗生素FR-008,对真菌具有很高的抗菌活性,并对蚊子幼虫有高毒性(袁德军和周启,1990)。负责合成FR-008的基因簇被定位(Hu et al.,1994),有21个基因(共138kb,GenBank accession number AY310323)被确认参与了抗生素FR-008的生物合成以及调节和外运(Chen et al.,2003)。然而,在FR-008基因簇最左端fscO基因上游的基因是否与FR-008抗生素生物合成相关?为此,本研究对FR-008基因簇上游区域进行了序列测定和分析。  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