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   129篇
  免费   10篇
  国内免费   1篇
林业   13篇
农学   9篇
  25篇
综合类   19篇
农作物   5篇
水产渔业   19篇
畜牧兽医   41篇
园艺   2篇
植物保护   7篇
  2022年   2篇
  2021年   6篇
  2018年   3篇
  2017年   5篇
  2016年   11篇
  2015年   4篇
  2014年   1篇
  2013年   12篇
  2012年   7篇
  2011年   8篇
  2010年   1篇
  2009年   3篇
  2008年   10篇
  2007年   9篇
  2006年   7篇
  2005年   10篇
  2004年   7篇
  2003年   9篇
  2002年   1篇
  2001年   4篇
  2000年   7篇
  1999年   2篇
  1998年   2篇
  1994年   1篇
  1993年   1篇
  1991年   1篇
  1980年   1篇
  1976年   1篇
  1975年   1篇
  1969年   1篇
  1968年   1篇
  1963年   1篇
排序方式: 共有140条查询结果,搜索用时 15 毫秒
131.
The inhibitory activity of carpropamid on scytalone dehydratase (SDH) extracted from a carpropamid-resistant strain of Magnaporthe grisea (Hebert) Barr was dramatically reduced in comparison with that on SDH extracted from the sensitive strain. A single-point mutation (G to A) located at the upstream region (233 bp downstream from the ATG codon) resulting in a one-amino-acid substitution (valine [GTG] 75 to methionine [ATG]: V75M) was found in the resistant strain. To examine whether the V75M mutation is the primary reason for decreasing the sensitivity of SDH to carpropamid, the SDH cDNAs of both the sensitive and the resistant strain were cloned into a GST-fused protein expression vector-system. The recombinant SDHs of both strains exhibited the same sensitivities to carpropamid as those extracted from the mycelia of the respective strains. These data clearly revealed that the V75M mutation causes the low sensitivities of the SDHs of the carpropamid-resistant strains, and strongly suggests that the V75M mutation confers resistance of these strains to carpropamid.  相似文献   
132.
The expressions of cytokeratin 8 and 18 (CK8 and CK18) in the normal canine skin (2 cases) and cutaneous adnexal tumors (127 cases) were investigated immunohistochemically. In the normal skin, co-expression of CK8/18 was found in the glandular epithelium of apocrine sweat glands, and single CK8-immunoreactivity was detected occasionally in the external root sheath at the isthmus and suprabulbar regions of the hair follicles. Neoplastic glandular epithelial cells in all apocrine gland tumors (21/21 cases, 100%) had co-expression of CK8/18. In trichoblastomas (27/28 cases, 96%), most neoplastic cells were diffusely positive for CK8, but those were negative for CK18. Single CK8-expression was also observed in basaloid neoplastic cells in several cases of trichoepitheliomas (7/19 cases, 37%) and pilomatricoma (1/7 cases, 14%). In several cases of trichoblastomas (4/28 cases, 14%) and trichoepitheliomas (2/19 cases, 11%), tumor cells forming glandular structures had co-expression of CK8/18. There were no positive reactions for both CK8 and 18 in infundibular keratinizing acanthomas, and sebaceous and hepatoid gland tumors. The present findings indicate that co-expression of CK8/18 is a specific feature of apocrine sweat glands and single CK8-expression represents the natures of external root sheath or pluripotential stem cells. Thus, the combination of CK8- and 18-immunostainings may have the utility to confirm the directions of differentiation in canine cutaneous adnexal tumors providing a reliable hallmark for histopathological diagnoses.  相似文献   
133.
It has been reported that mature adipocyte-derived dedifferentiated fat (DFAT) cells show multilineage differentiation potential similar to that observed in mesenchymal stem cells. Since DFAT cells can be prepared from a small quantity of adipose tissue, they could facilitate cell-based therapies in small companion animals such as cats. The present study examined whether multipotent DFAT cells can be generated from feline adipose tissue, and the properties of DFAT cells were compared with those of adipose-derived stem cells (ASCs). DFAT cells and ASCs were prepared from the floating mature adipocyte fraction and the stromal vascular fraction, respectively, of collagenase-digested feline omental adipose tissue. Both cell types were evaluated for growth kinetics, colony-forming unit fibroblast (CFU-F) frequency, immunophenotypic properties, and multilineage differentiation potential.DFAT cells and ASCs could be generated from approximately 1 g of adipose tissue and were grown and subcultured on laminin-coated dishes. The frequency of CFU-Fs in DFAT cells (35.8%) was significantly higher than that in ASCs (20.8%) at passage 1 (P1). DFAT cells and ASCs displayed similar immunophenotypes (CD44+, CD90+, CD105+, CD14?, CD34? and CD45?). Alpha-smooth muscle actin-positive cells were readily detected in ASCs (15.2 ± 7.2%) but were rare in DFAT cells (2.2 ± 3.2%) at P1. Both cell types exhibited adipogenic, osteogenic, chondrogenic, and smooth muscle cell differentiation potential in vitro. In conclusion, feline DFAT cells exhibited similar properties to ASCs but displayed higher CFU-F frequency and greater homogeneity. DFAT cells, like ASCs, may be an attractive source for cell-based therapies in cats.  相似文献   
134.
In the present study, we examined the effect of high water temperature on brain-pituitary-gonad (B-P-G) axis of a perciform fish red seabream, Pagrus (Chrysophrys) major during its spawning season (April-May). High water temperature negatively affected all levels in B-P-G axis and turned out to be the termination factor of the spawning season of this species.  相似文献   
135.
比较了NaOH和Na2CO3对水冬瓜油(酸值22 mg/g)的碱炼效果,并应用正交和单因子试验,分析了Na2CO3溶液浓度、反应温度、反应搅拌强度和水洗温度4种因子对水冬瓜油碱炼降酸效果的影响,确定了碱炼降酸的最佳Na2CO3用量和Na2CO3碱炼水冬瓜油的最优工艺条件。结果表明,Na2CO3碱炼效果优于NaOH;以碱炼油的得率和酸值为指标,Na2CO3碱炼水冬瓜油的最佳反应条件为:Na2CO3水溶液浓度为170 g/L,反应温度为75℃,搅拌速度为100 r/min,水洗温度为80℃,固体Na2CO3用量为105 g/kg;在此条件下,水冬瓜毛油的酸值可降至1mg/g以下,可作为碱催化酯交换法制备生物柴油的原料。  相似文献   
136.
137.
138.
A high-pressure phase of TiO(2), which had been observed by shock-wave experiments and remained unresolved, has been studied by in situ x-ray diffraction. The single phase was formed at 20 gigapascals and 770 degrees C with the use of sintered-diamond multianvils; it has the same structure as baddeleyite, the stable phase of ZrO(2) at ambient conditions. The coordination number of Ti increases from six to seven across the rutile to baddeleyite transition, and the volume is reduced by approximately 9 percent.  相似文献   
139.
Understanding the seasonal and regional patterns of nitrogen (N) components in the headwaters of forested watersheds is important for forests management. Here, we investigated the NO3-N concentration and its seasonal variations in the baseflow headwaters in Japanese coniferous forests with different N saturation status in five regions (i.e., Nagano, Tokyo, Aichi, Kochi and Mie). We found that the ratios of NO3-N to DON were significantly higher in the N-saturated regions including Nagano (14.1 ± 2.2) and Tokyo (16.5 ± 4.1), compared with the regions, which didn't experience N saturation including Aichi (1.4 ± 0.2), Kochi (5.1 ± 1.8), and Mie (2.2 ± 0.5). In comparison with the regions without experiencing N saturation, the relatively higher NO3-N concentration, as well as its contrastive variation between growing season and dormant season, was also characteristic of the seasonal NO3-N concentration in the N-saturated regions. Our findings have indicated that NO3-N concentration, its seasonal variations, and the ratio of NO3-N to DON, are the better and applicable indicators for evaluating N saturation status in Japanese coniferous forests.  相似文献   
140.
Soybeans planted in early to mid-June (early) are less affected by rainfall during rainy season than those conventionally planted in early to mid-July in southwestern Japan. Also, narrow row cultivation is expected to increase soybean yield and save labor for inter-tillage and ridging. Field experiments were performed in 2014 and 2015 to test the effect of plant density (high, middle, and low) under early planting condition on growth, yield, and several agronomical traits of Sachiyutaka A1 and three new genotypes (Sakukei 155, Kanto 127 and Shikoku 15). Early planting was performed in mid- to late June, even though rainy season started in early June. Higher plant densities produced 13% greater yield than low plant density through an increase in biomass accumulation, especially at R5. Among yield components, only pods m?2 was significantly and positively correlated with yield, indicating that an increase in pods m?2 led to a greater yield with higher plant densities. The yields of Sachiyutaka A1 were relatively stable for two years, but the lodging resistance should be further improved. Shikoku 15 had greater yield potential and lodging resistance, but its resistance to damping-off disease should be improved. Sakukei 155 with medium plant density produced relatively high and stable yield with less lodging. Although the yield of Kanto 127 fluctuated between experimental years, this genotype showed higher yield potential in higher plant densities with less lodging in 2015. Thus, Sakukei 155 and Kanto 127 with high or medium density may be suitable for early planting in this region.  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