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   450篇
  免费   21篇
  国内免费   1篇
林业   18篇
农学   20篇
  71篇
综合类   19篇
农作物   28篇
水产渔业   71篇
畜牧兽医   183篇
园艺   2篇
植物保护   60篇
  2022年   2篇
  2021年   18篇
  2020年   8篇
  2019年   9篇
  2018年   10篇
  2017年   16篇
  2016年   17篇
  2015年   7篇
  2014年   18篇
  2013年   30篇
  2012年   22篇
  2011年   24篇
  2010年   16篇
  2009年   18篇
  2008年   38篇
  2007年   29篇
  2006年   30篇
  2005年   27篇
  2004年   21篇
  2003年   32篇
  2002年   15篇
  2001年   15篇
  2000年   10篇
  1999年   13篇
  1998年   1篇
  1997年   3篇
  1996年   3篇
  1994年   2篇
  1993年   1篇
  1992年   6篇
  1991年   4篇
  1990年   3篇
  1989年   2篇
  1984年   1篇
  1973年   1篇
排序方式: 共有472条查询结果,搜索用时 156 毫秒
41.
To clarify the cellular source and secretory pattern of inhibin in the Japanese quail during follicular development, the plasma concentrations of immunoreactive (ir) inhibin were measured from 1 to 7 weeks after hatching. Localization of the inhibin/activin alpha, beta A and beta B subunits was investigated by immunohistochemistry. To monitor development of the pituitary and ovarian functions, the plasma luteinizing hormone (LH) and progesterone concentrations were also measured. Ovarian weight increased gradually until 6 weeks of age and then abruptly increased at 7 weeks of age just at the onset of egg production. Plasma concentrations of LH increased significantly at 6 weeks of age. The plasma concentrations of ir-inhibin and progesterone and the pituitary contents of LH also increased significantly at 7 weeks of age. Immunohistochemically, the inhibin/activin alpha, beta A and beta B subunits were localized in the granulosa cells of all follicles during different stages of development from 1 to 7 weeks after hatching. The inhibin alpha, beta A and beta B subunits were also found in the interstitial cells but not theca cells of all follicles. These results demonstrated that the plasma concentrations of ir-inhibin of the female Japanese quails rose with ovarian development. The immunohistochemical results suggested that granulosa and interstitial cells are the major source of ovarian inhibins in female Japanese quails.  相似文献   
42.
We compared the hair cortisol levels of lactating dairy cows in a cold‐ and a warm‐temperate region out of four climatic zones in Japan. We simultaneously investigated the effects of calving number, lactation period and month of hair sampling. Hair of nine Holstein lactating cows chosen from each region (i.e. 18 cows per sampling) was sampled in March, June, September and December. Number of calvings (1, 2, ≥3) and lactation duration (early: <100, middle: 101–200, and late: >201 days) were balanced between regions. Cortisol was extracted from hair by methanol, and its level was determined with a cortisol immunoassay kit. A multi‐way analysis of variance revealed that the effects of month of hair sampling (P < 0.001) and its combination with region (P < 0.05) were significant. In a multiple comparison test, significant differences (P < 0.01) in hair cortisol level (pg/mg of hair) were found between June (13.0 ± 1.0) and the other 3 months, and between September (1.6 ± 0.2) and December (4.5 ± 0.3). The rise in cortisol level from March to June was more intense in the cold‐temperate region. These results demonstrate the necessity of considering seasonal variations in each climatic region when we use hair cortisol level as an indicator of stress.  相似文献   
43.
44.
Black spot disease, which is caused by the Japanese pear pathotype of the filamentous fungus Alternaria alternata (Fries) Keissler, is one of the most harmful diseases in Japanese pear cultivation. We mapped a gene for susceptibility to black spot disease in the Japanese pear (Pyrus pyrifolia Nakai) cultivar ‘Kinchaku’ (Aki gene) at the top of linkage group 11, similar to the positions of the susceptibility genes Ani in ‘Osa Nijisseiki’ and Ana in ‘Nansui’. Using synteny-based marker enrichment, we developed novel apple SSR markers in the target region. We constructed a fine map of linkage group 11 of ‘Kinchaku’ and localized the Aki locus within a 1.5-cM genome region between SSR markers Mdo.chr11.28 and Mdo.chr11.34. Marker Mdo.chr11.30 co-segregated with Aki in all 621 F1 plantlets of a ‘Housui’ × ‘Kinchaku’ cross. The physical size of the Aki region, which includes three markers (Mdo.chr11.28, Mdo.chr11.30, and Mdo.chr11.34), was estimated to be 250 Kb in the ‘Golden Delicious’ apple genome and 107 Kb in the ‘Dangshansuli’ Chinese pear genome. Our results will help to identify the candidate gene for susceptibility to black spot disease in Japanese pear.  相似文献   
45.
Emphysematous cystitis is a rare disorder caused by bacterial infection and characterized by gas accumulation within the bladder wall with cyst formation. This report describes the histopathological characteristics of emphysematous cystitis found in a diabetic female beagle induced by streptozotocin and alloxan. Macroscopically, multiple cyst-like structures were observed on the cut surface of the urinary mucosa. During fixation, small specimens cut from the mucosa floated on the surface of the fixative solution. Histopathologically, multiple cysts were lined with a single layer of flattened cells found to be immunohistochemically positive for vimentin, partially positive for α-smooth muscle actin or macrophage scavenger receptor, class A, and thought to be myofibroblasts, fibroblasts or macrophages. Multinucleated giant cells were observed around the cysts, and gram-negative short bacilli were observed in the lumen of the urinary bladder. From these findings, this case was diagnosed as emphysematous cystitis.  相似文献   
46.
47.
Blooms of toxic dinoflagellates of the genus Ostreopsis, which is known as a producer of palytoxin (PTX) analogs, may pose a threat to human health in tropical, subtropical, and temperate regions around the world. In the present study, we established a suitable culture method for Ostreopsis spp. isolated from Japanese coastal waters and characterized their growth potential using the method to discuss their bloom dynamics. Each clonal strain of Ostreopsis cf. ovata, Ostreopsis sp.?1, Ostreopsis sp.?5, and Ostreopsis sp.?6 was incubated in 25?×?150?mm test tubes with a flat bottom containing various kinds of medium. Since Ostreopsis spp. strains grew well in IMK and/or f/2 media, we selected these media for cultivation of all the Ostreopsis spp. isolates. Growth rates of O. cf. ovata (0.834?divisions/day), Ostreopsis sp.?1 (0.619?divisions/day), and Ostreopsis sp.?6 (1.04?divisions/day) that produce PTX analogs significantly differed (p?<?0.05) respectively and are clearly higher than those of other reported epiphytic dinoflagellate Gambierdiscus toxicus, Prorocentrum lima, and Coolia monotis cultures, which suggest that these species have ecological advantages to predominate through the algal succession in Japanese coastal waters, resulting in a potential risk to human health in this region.  相似文献   
48.
Previous studies have indicated that some leptin gene polymorphisms were associated with economically important traits in cattle breeds. However, polymorphisms in the leptin gene have not been reported thus far in Japanese Black cattle. Here, we aimed to identify the leptin gene polymorphisms which are associated with carcass traits and fatty acid composition in Japanese Black cattle. We sequenced the full‐length coding sequence of leptin gene for eight Japanese Black cattle. Sequence comparison revealed eight single nucleotide polymorphisms (SNPs). Three of these were predicted to cause amino acid substitutions: Y7F, R25C and A80V. Then, we genotyped these SNPs in two populations (JB1 with 560 animals and JB2 with 450 animals) and investigated the effects on the traits. Y7F in JB1 and A80V in JB2 were excluded from statistical analysis because the minor allele frequencies were low (< 0.1). Association analysis revealed that Y7F had a significant effect on the dressed carcass weight in JB2; R25C had a significant effect on C18:0 and C14:1 in JB1 and JB2, respectively; and A80V had a significant effect on C16:0, C16:1, C18:1, monounsaturated fatty acid and saturated fatty acid in JB1. The results suggested that these SNPs could be used as an effective marker for the improvement of Japanese Black cattle.  相似文献   
49.
Two-dimensional condensation was initiated in a self-assembled mixed monolayer of spiropyran and octadecanol by a nanosecond laser pulse. The dynamics of the process were monitored using nanosecond pump-probe Brewster angle microscopy. Domain growth followed a power law with a growth exponent of 0.47 at a velocity approaching 20?ms(-1). This represents a limit for the rate of longitudinal signaling of pressure waves through a self-assembled amphiphilic layer at an interface and adds to our understanding of signal transmission rates in biomimetic membranes where morphological change in one region can be signaled to a more remote region.  相似文献   
50.
We report here the interesting case of a 5-year-old male cynomolgus monkey with goblet cell hyperplasia and thickening of the muscular layer throughout the small intestine without exhibiting any clinical symptoms. Necropsy examination showed diffuse thickening of the intestinal wall from the jejunum to the ileum, with an appearance likened to a rubber tube. Histopathologically, marked thickening was observed in both the mucosal and muscular layers in the jejunum and ileum, and slight thickening was observed in the duodenum. Goblet cell hyperplasia with extension of the circular folds and villi was prominently observed. The mucosal surface was covered with a thick mucus layer containing desquamated mucosal epithelial cells, and both the inner and outer muscular layers were markedly thickened due to smooth muscle hypertrophy. Neither macroscopic nor histopathological examination identified any causative factors, such as infection, enteritis and intestinal stenosis, or obstruction that may have caused development of this lesion. Given these observations, this case may simply be considered of spontaneous goblet cell hyperplasia and muscular layer thickening in the small intestine of a cynomolgus monkey.  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