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   335篇
  免费   9篇
  国内免费   1篇
林业   12篇
农学   12篇
  64篇
综合类   13篇
农作物   11篇
水产渔业   37篇
畜牧兽医   164篇
园艺   3篇
植物保护   29篇
  2023年   2篇
  2022年   6篇
  2021年   13篇
  2020年   4篇
  2019年   3篇
  2018年   4篇
  2017年   11篇
  2016年   7篇
  2015年   13篇
  2014年   23篇
  2013年   25篇
  2012年   16篇
  2011年   19篇
  2010年   5篇
  2009年   14篇
  2008年   27篇
  2007年   24篇
  2006年   23篇
  2005年   23篇
  2004年   24篇
  2003年   19篇
  2002年   21篇
  2001年   4篇
  2000年   4篇
  1999年   4篇
  1998年   3篇
  1997年   1篇
  1996年   1篇
  1992年   1篇
  1990年   1篇
排序方式: 共有345条查询结果,搜索用时 15 毫秒
271.
In order to determine the time for terminating Ipomoea coccinea control in Japanese soybean‐growing systems, the relationship between the relative photosynthetic photon flux density at the emergence time of I. coccinea seedlings and their fate in competition with a Japanese determinate soybean cultivar, “Hatayutaka”, was investigated. A 2 year field study was conducted, in which I. coccinea was seeded at 0, 5 and 7 weeks after seeding of the soybean in 2010 and once per week between 0 and 7 weeks after seeding in 2011, while soybean was seeded in six plots at three different seeding times and two different row‐spacing arrangements with the same intrarow spacing. The results showed that the I. coccinea seedlings that emerged at a relative photosynthetic photon flux density of <49% grew weak or died. At this value, the canopy height‐to‐row spacing ratio of soybean was very stable, regardless of the row spacing, in both study years. This ratio was also stable when tested on 11 different soybean cultivars that covered all cultivation areas of Japan and had various growth speeds during the early growing period. A canopy height‐to‐row spacing ratio of 1.0 could be a simple and practical onsite index for determining the time to terminate I. coccinea control in Japanese soybean‐growing systems.  相似文献   
272.
Porcine zona pellucida proteins (ZPs) have been utilized as female immunocontraceptive antigens. The purpose of this study was to explore the potential use of silkworm recombinant bovine ZP4 as an alternative. When the protein was injected with monophosphoryl lipid A (MPL) – an immuno-stimulative agent – into two female goats, marked elevation of the anti-ZP4 titer was detected. Application of the purified specific IgG to a porcine in vitro fertilization system reduced the sperm penetration rate. In one goat, the cyclic profile of serum progesterone disappeared as the anti-ZP4 titer increased. Histological examination of the ovaries revealed degeneration of antral follicles with sparse infiltration of inflammatory cells in the theca, indicating that autoimmune oophoritis had been induced. Together, the present results suggest that recombinant ZP4 disturbs fertilization and exerts a pathogenic effect on follicle development in goats, thus indicating its potential as a female immunocontraceptive antigen.  相似文献   
273.
274.
The effects of amylose content and other starch properties on concentrated starch gel properties were evaluated using 10 wheat cultivars with different amylose content. Starches were isolated from grains of two waxy and eight nonwaxy wheat lines. The amylose content of waxy wheat lines was 1.4–1.7% and that of nonwaxy lines was 18.5–28.6%. Starch gels were prepared from a concentrated starch suspension (30 and 40%). Gelatinized starch was cooled and stored at 5°C for 1, 8, 16, 24, and 48 hr. The rheological properties of starch gels were studied by measuring dynamic viscoelasticity with parallel plate geometry. The low‐amylose starch showed a significantly lower storage shear modulus (G′) than starches with higher amylose content during storage. Waxy starch gel had a higher frequency dependence of G′ and properties clearly different from nonwaxy starches. In 40% starch gels, the starch with lower amylose showed a faster increase in G′ during 48 hr of storage, and waxy starch showed an extremely steep increase in G′. The amylose content and concentration of starch suspension markedly affected starch gel properties.  相似文献   
275.
Nicotinic acetylcholine receptor-channels (AChR) are believed to be the target site of cartap. In order to clarify the mechanisms of the cartap interaction with nicotinic AChRs, single-channel patch clamp experiments were performed using rat clonal phaeochromocytoma (PC12) cells. Cartap increased the short closures occurring during single-channel openings induced by acetylcholine (ACh). Thus, when co-applied with acetylcholine, cartap markedly shortened the open time associated with bursts. These effects were voltage-dependent, being more prominent at negative voltages. These results strongly suggest that cartap acts as an open channel blocker at the neuronal nicotinic AChR. © 1999 Society of Chemical Industry  相似文献   
276.
The mineral composition of taro ( Colocasia esculenta (L.) Schott) was analyzed to develop a method to distinguish taro produced in Japan and China. The concentrations of 15 elements (Al, Ca, Cl, Mg, Mn, Br, Co, Cr, Cs, Fe, K, Na, Rb, Sc, Zn) were assayed using instrumental neutron activation analysis. The concentrations of NO(3)(-), SO(4)(2-), H(2)PO(4)(-), Cl(-), malate, and oxalate were measured by ion chromatography. The mean concentrations of H(2)PO(4)(-), Co, Cr, and Na significantly differed (P < 0.01) between taro grown in Japan and that grown in China. Discriminant analysis was performed to identify the most efficient combination of elements and compounds to discriminate the taro geographic origin. The highest percentage of correct classification was achieved with a two-variable model including H(2)PO(4)(-) and Co (100% for Japanese, 93.75% for Chinese). Principal component analysis and cluster analysis using all of the assayed elements and compounds were also conducted to determine which elements significantly accounted for the variation of the taro mineral composition. We report on the potential of H(2)PO(4)(-) and Co concentrations to differentiate taro grown in China and Japan and discuss the sources of variability in the taro mineral composition of our samples.  相似文献   
277.
黄瓜(Cucumis sativusL.)是典型的冷敏型植物。对黄瓜来说,冷害是生产上制约其丰产、优质的主要逆境因素之一。为了掌握黄瓜耐冷性遗传规律,加快黄瓜耐冷品种的选育,本研究选取黄瓜耐冷型品系0839和低温敏感型品系B52为亲本杂交得到F1和F2,进行苗期低温鉴定和遗传分析。供试亲本的耐冷性主要受一对显性单基因控制。结合BSA(群体分离分析)和SSR分子标记,获得了与黄瓜耐冷性主效基因连锁的SSR标记。通过F2群体分析,鉴定出与耐冷性基因连锁的分子标记SSR07248,该标记与耐冷性基因间的遗传距离为32.6cM。  相似文献   
278.
A cat was presented with depression and anorexia. The complete blood cell count (CBC) revealed non-regenerative anemia (PCV, 8.5%), marked thrombocytopenia (2,400/µl), and leukocytosis (32,090/µl). In the peripheral blood, proliferation of blast cells (85%; 27,276/µl) and basophils (7.7%; 2,460/µl) was observed. Bone marrow aspirate showed hyperplasia with 8.8% blasts and 90.2% basophils of all nucleated cells. The blast cells were negative for myeloperoxidase staining and positive for alpha-naphthol butyrate esterase staining, indicating the agranular blasts are monoblasts. Thus, acute monoblastic leukemia (M5a) with chronic basophilic leukemia was diagnosed. Basophils accounted for more than 40% of the bone marrow, and we diagnosed secondary basophilic leukemia. Secondary basophilic leukemia should be included in the differential list when abnormal basophil increases are observed in feline bone marrow.  相似文献   
279.
Apple is a fruit crop of significant economic importance, and breeders world wide continue to develop novel cultivars with improved characteristics. The lengthy juvenile period and the large field space required to grow apple populations have imposed major limitations on breeding. Various molecular biological techniques have been employed to make apple breeding easier. Transgenic technology has facilitated the development of apples with resistance to fungal or bacterial diseases, improved fruit quality, or root stocks with better rooting or dwarfing ability. DNA markers for disease resistance (scab, powdery mildew, fire-blight, Alternaria blotch) and fruit skin color have also been developed, and marker-assisted selection (MAS) has been employed in breeding programs. In the last decade, genomic sequences and chromosome maps of various cultivars have become available, allowing the development of large SNP arrays, enabling efficient QTL mapping and genomic selection (GS). In recent years, new technologies for genetic improvement, such as trans-grafting, virus vectors, and genome-editing, have emerged. Using these techniques, no foreign genes are present in the final product, and some of them show considerable promise for application to apple breeding.  相似文献   
280.
Feline upper respiratory tract infection due to Aspergillus spp. is considered an emerging disease, with the number of reported cases continuing to rise. In this study, we report the first case of feline sinonasal aspergillosis caused by Aspergillus fischeri in Japan. The patient presented after 2 months of progressive facial deformity around the nose and nasal discharge. The isolate from this case was susceptible to itraconazole (ITZ), voriconazole and micafungin, but was resistant to amphotericine B. However, the infected cat died approximately 1 month after referral, despite treatment for 12 days ITZ administered orally at 10 mg/kg.  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