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   247篇
  免费   4篇
  国内免费   1篇
林业   12篇
农学   5篇
  26篇
综合类   14篇
农作物   10篇
水产渔业   31篇
畜牧兽医   127篇
植物保护   27篇
  2022年   5篇
  2021年   9篇
  2020年   4篇
  2019年   2篇
  2018年   3篇
  2017年   3篇
  2016年   9篇
  2015年   10篇
  2014年   10篇
  2013年   8篇
  2012年   12篇
  2011年   26篇
  2010年   5篇
  2009年   10篇
  2008年   20篇
  2007年   14篇
  2006年   13篇
  2005年   21篇
  2004年   10篇
  2003年   9篇
  2002年   7篇
  2001年   6篇
  2000年   3篇
  1999年   3篇
  1998年   2篇
  1997年   3篇
  1996年   2篇
  1995年   2篇
  1994年   1篇
  1992年   1篇
  1991年   6篇
  1990年   1篇
  1989年   3篇
  1988年   2篇
  1987年   1篇
  1981年   1篇
  1980年   1篇
  1979年   1篇
  1977年   1篇
  1967年   2篇
排序方式: 共有252条查询结果,搜索用时 62 毫秒
41.
Absorption by the tap-root and by different nodal roots of white clover S100 and translocation of 32P were investigated to find to what extent nodal roots can compensate for the absence of a tap-root. 32P absorbed from the tap-root was distributed evenly within the whole plant. When translocation from the 2nd and 7th nodal roots was studied, similar distribution was obtained only from the nodal root closer to the centre of the plant. The backward movement of 32P absorbed from nodal roots at the base of the plant increased as the root size increased. Removal of tap-roots resulted in temporary depression of translocation; its effect disappeared within 3 weeks.
It is concluded that the ability of nodal roots to compensate for loss of the tap-root depends on their position and size.  相似文献   
42.
To investigate the effects of high and low somatostatinergic tone on GH-releasing peptide-2 (GHRP-2) and GH-releasing hormone (GHRH)-induced growth hormone (GH) secretion in swine, we examined GHRP-2- and GHRH-induced GH secretion after pretreatment with atropine or pyridostigmine. Pretreatment of swine with atropine (80 µg/kg bodyweight (BW), intravenous (i.v.)) 15 min before i.v. administration of saline, GHRP-2 (30 µg/kg BW), GHRH (1 µg/kg BW) or a combination of GHRP-2 and GHRH, reduced plasma GH area under the curve ( P  < 0.05), completely blocked GH response to GHRH, and attenuated GH response to GHRP-2 and GHRH combined ( P  < 0.05), without affecting GH response to GHRP-2 only. A synergistic effect of GHRP-2 and GHRH was not observed. In contrast, pretreatment of swine with pyridostigmine (100 µg/kg BW, i.v.), under the same pretreatment conditions as above, increased plasma GH concentration ( P  < 0.01), augmented GH response to GHRP-2 ( P  < 0.05), and GHRP-2 and GHRH combined ( P  < 0.05), but did not affect GH response to GHRH. These results suggest that the cholinergic muscarinic agents atropine and pyridostigmine modulate the GH response to GHRP-2 and GHRH, and that GHRP-2 acts antagonistically on the inhibitory effect of somatostatin in swine.  相似文献   
43.
44.
We evaluated the influence on milk production of feeding early lactation cows a diet that included 14.5% crude protein (CP) and that did not meet methionine (Met) requirements or that met them by supplying rumen‐protected Met (RPMet). Thirty‐nine multiparous Holstein cows were allocated into two groups. For 15 weeks after calving, each group was fed one of the two total mixed rations, Control (= 20) or Treatment (= 19). The Treatment group received added RPMet at 0.034% (8 g/day) of the Control diet on dry matter basis. The adequacies of Met for the Control and Treatment groups were 96% and 106%, respectively, and for other amino acids, >110%. The CP level (14.5%) was 1 percentage point lower than that recommended by the Japanese Feeding Standard (2006). No between‐group differences were found in milk yield (40 kg/day), milk composition, plasma profile, rumen fermentation, nitrogen balance, or cow health. Met intake and the amount of rumen‐undegradable feed Met were higher in the Treatment group (< 0.05). Microbial Met and total metabolizable Met did not differ between groups. Supplying RPMet in a 14.5% CP diet during early lactation did not dramatically affect milk production, because the amount of total metabolizable Met was unchanged.  相似文献   
45.
Conclusions When the hydroxyl values of materials containing phenolic 3 or sterically hindered hydroxyl groups were determined by the esterification method, the values were considerably smaller than the theoretical values. In contrast, the NCO method provided hydroxyl values much closer to the theoretical values for such materials, though the values varied depending on the kinds and amounts of catalysts.The quantity of hydroxyl groups reacting with the NCO group could be directly determined by the NCO method using a catalyst mixture consisting of DABCO and DBTDL in a molar ratio of 21. Therefore, this method can be considered useful for determining the hydroxyl value before preparing polyurethane from liquefied wood or bark.Part of this paper was presented at the 51st Annual Meeting of the Japan Wood Research Society, Tokyo, April 1988  相似文献   
46.
The indirect fluorescent antibody test (IFAT) revealed seropositivity to Coxiella burnetii in aged non-laying chickens in poultry farms in a prefecture in the central part of Japan. Seropositivity was 7%, and antibody titers ranged from 16 to 64. No DNA fragment specific for C. burnetii was detected in the chickens by nested-PCR. The prevalence of C. burnetii infection in a prefecture of Japan in which poultry farming prospers was 7%.  相似文献   
47.
Commercial western blot (WB) assay was used to detect serum antibodies specific to Echinococcus multilocularis in 23 horses in which infection was confirmed by postmortem inspection at a slaughterhouse. Livers contained from 1 to >20 nodular lesions; foci diameter ranged from 1 to 25 mm. Antibody tests of serum from all 23 animals were negative for antigen bands at 7, 16, 18, and 26-28 kDa, which show specificity in the serum of human patients. However, sera from two infected horses with the largest nodules (diameter, 25 mm) showed positive response to one of the 22-kDa and 30-kDa antigen bands. It may be possible to diagnose E. multilocularis infection in horses based on the detection of these bands on commercial WB assay.  相似文献   
48.
A 15-year-old Dutch Warmblood gelding suddenly developed incoordination and hindlimb stumbling. The horse had a history of eyelid lymphoma. Necropsy revealed yellow-white or dark reddish-brown masses adhering to the outer surface of the spinal dura mater from the first cervical vertebra to the seventh thoracic vertebra. The spinal cord close to the first cervical vertebra and the seventh thoracic vertebra was markedly compressed by the masses filling the epidural space. The masses were also observed in the larynx, eyelids, and adipose-rich tissues, including the joints and orbits. They appeared similar in shape. The mandibular, retropharyngeal, axillary, superficial inguinal, deep inguinal, and lateral iliac lymph nodes were solid and enlarged. Histologically, the masses were composed of small or medium-sized lymphocyte-like tumor cells, but atypical cells and mitotic figures were rare. There were moderate infiltrations of macrophages and multinucleated giant cells, which were occasionally ingesting the surrounding tumor cells. Immunohistochemically, the tumor cells were classified as T-cell-derived cells. Throughout the spinal cord, enlargement or loss of nerve axons, dilation of periaxonal spaces, and macrophage infiltration into periaxonal spaces were observed, mainly in the ventral funiculus. Spinal cord compression by the tumor mass was suggested as a cause of the locomotive dysfunction. This is the first report of equine lymphoma with ataxia located from the proximal cervical to middle thoracic dura mater and in joint cavities.  相似文献   
49.
A case was discovered where the embryo transfer (ET) calf had been infected with bovine leukemia virus (BLV) from the recipient cow. The embryo was transferred from the BLV-uninfected donor cow to the recipient cow. However, the BLV test had not been performed to the recipient cow before ET was performed. The ET calf was raised in a calf hatch from birth to 1-month old and was given the recipient cow's colostrum and milk artificially. The ET calf was raised with the two other calves from a 1-month old to a 6-month old. The BLV test was performed to the ET calf by agar gel precipitation (AGP) and passive haemagglutination (PHA) assay when the ET calf was 6 months old. Because the ET calf was positive, the BLV test was performed to the recipient cow, the two other calves raised with the ET calf and the two dams of the two other calves. Because the recipient cow only was positive at the time of the first test, we judged that the ET calf had been infected with BLV from the recipient cow. The importance of the BLV test being carried out on the recipient cow for the prevention of enzootic bovine leukemia in a case of ET was recognised.  相似文献   
50.
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