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   329篇
  免费   4篇
  国内免费   1篇
林业   40篇
农学   14篇
  37篇
综合类   17篇
农作物   8篇
水产渔业   42篇
畜牧兽医   133篇
园艺   6篇
植物保护   37篇
  2023年   4篇
  2022年   9篇
  2021年   11篇
  2020年   6篇
  2019年   5篇
  2018年   8篇
  2017年   3篇
  2016年   9篇
  2015年   15篇
  2014年   12篇
  2013年   20篇
  2012年   19篇
  2011年   22篇
  2010年   8篇
  2009年   10篇
  2008年   21篇
  2007年   18篇
  2006年   20篇
  2005年   13篇
  2004年   23篇
  2003年   23篇
  2002年   22篇
  2001年   15篇
  2000年   7篇
  1999年   3篇
  1998年   2篇
  1997年   3篇
  1996年   1篇
  1995年   1篇
  1978年   1篇
排序方式: 共有334条查询结果,搜索用时 0 毫秒
181.
Defensins are generally implicated in the quick resistance of epithelial surfaces to microbials; however, recent reports have indicated that defensins also have unknown purposes in relation to noninfectious diseases. In this study, the localization patterns of anti-microbial peptides, β defensins (BDs), in the tracheal epithelium of male C3H mice under exposure to toluene were analyzed by immunohistochemistry. Mice were exposed one to ten times to toluene for 30 min by nose-only inhalation. Expression of BDs was revealed by immunohistochemistry in serial sections of trachea after the final exposure. Expression of BD-1 was usually observed at almost the same levels in all exposure groups, and expression of BD-2 was observed in the control group; however, the signals for BD-2 decreased gradually with frequency of exposure. In the group exposed ten times, expression of BD-2 decreased to far lower than that of the control group. No expression of BD-3 was detected in any groups. Interestingly, expression of BD-4 increased to the maximum in the group exposed four times and decreased to a level lower than that of the control in the group exposed ten times. The results of the present study indicated that toluene gas might change the expression pattern of BDs in the tracheal epithelial cells. The oscillation of expression of BD-4 was quite characteristic and might contribute to morphological damage in on the epithelial cells.  相似文献   
182.
Ion beam irradiation is attracting attention in floriculture as a means of inducing mutations. We investigated the effect of ion beam irradiation on induction of ray florets color/shape mutants from two strains of chrysanthemum to create new flower cultivars. The ray florets and leaf explants of chrysanthemum cultivars, ‘Shiroyamate’ and ‘H13’, respectively, cultured on MS medium were irradiated with 12C5+ ion beam at doses of 1, 2, 4 and 8Gy. The frequency of shoot primordia formation on ray florets explants of ‘Shiroyamate’ and shoot bud formation on leaf explants of ‘H13’ was decreased by 8Gy and 4Gy irradiation, respectively. The effective dose of ion beam was less than 4Gy in ‘Shiroyamate’ and less than 2Gy in ‘H13’. After exposure to an effective dose of ion beam, regenerated plants were grown in a green-house and the field. Yellow ray florets mutants from ‘Shiroyamate’, and various ray florets color mutants (dark-red, light red, pink, pink spray) and a flower shape mutant (double-ray florets) from ‘H13’ were induced by ion beam irradiation. Furthermore, a white mutant was obtained from a chimeric mutant. These results suggest that the combination of ion beam irradiation and tissue culture would be an effective means of generation mutants at a high efficiency.  相似文献   
183.
184.
185.
In the present study, we have developed an allele-specific primer-polymerase chain reaction (ASP-PCR) for genotyping a single nucleotide polymorphism (SNP) of swine Toll-like receptor 2 (TLR2) (C406G), which is related to the prevalence of pneumonia caused by Mycoplasma hyopneumoniae. We also compared the allele frequency among several pig breeds of Japan and the Czech Republic. Allele-specific primers were constructed by introducing 1-base mismatch sequence before the SNP site. The swine TLR2 C406G mutation was successfully determined by the ASP-PCR using genomic DNA samples in Japan as previously genotyped by a sequencing method. Using the PCR condition determined, genomic DNA samples from pig blood obtained from 110 pigs from 7 different breeds in the Czech Republic were genotyped by the ASP-PCR. The genotyping results from the ASP-PCR were completely matched with the results from the sequencing method. The allele frequency of the swine TLR2 C406G mutation was 27.5% in the Czech Republic and 3.6% in Japan. The C406G mutation was only found in the Landrace breed in Japan, and was almost exclusively found in the Landrace breed in the Czech Republic as well. These results indicated the usefulness of ASP-PCR for detecting a specific SNP for swine TLR2.  相似文献   
186.
187.
To investigate the hemodynamic effects on seven anesthetized dogs with experimentally-induced mitral insufficiency, isosorbide dinitrate (ISDN) in sustained release form (EV151) was administered at different dosages (0, 2, 8 and 16 mg/kg). The drug administration resulted in altered pulmonary arterial wedge pressure (preload), and cardiac output and total systemic resistance (afterload). Arterial pressure increased in the control group and in animals receiving 2 mg/kg, but decreased in animals 1-2 hr after receiving 8 and 16 mg/kg dosages. Cardiac output increased in animals receiving 2, 8 and 16 mg/kg dosages, with concomitant decreases in total systemic resistance. ISDN caused mild vasodilation at 2 mg/kg and severe vasodilation at 8 and 16 mg/kg. Future experiments on non-anesthetized dogs may be of benefit.  相似文献   
188.
单叶蔷薇的花芽形态分化   总被引:5,自引:0,他引:5  
 单叶蔷薇花芽分化从3月下旬开始至4月下旬完成, 历时30 d, 其过程可分为形态分化前、苞叶原基分化期、萼片原基分化期、花瓣原基分化期、雄蕊原基分化期、雌蕊原基分化期。其中花瓣原基的分化只进行1次, 这是形成单轮花瓣的原因。各花器官原基起源于花分生组织的边缘区细胞。生殖生长锥直径和细胞数的增加在生长锥膨大期和心皮分化期较高。  相似文献   
189.
190.
To expand the utilization of waste newspapers and lignin, activated carbon (AC) sheets, as an example of AC moldings, were prepared from those mixtures. The isolated lignins used were softwood and hardwood acetic acid lignins (SAL and HAL), softwood kraft lignin (KL), and wheat-straw lignin (WSL). The mixtures were molded into precursory sheets by thermal compression and then converted to AC sheets by carbonization and steam activation. The flexural strength of the precursory sheets was dramatically improved by additing the lignins compared to that of sheets without lignin. The strength of several sheets was more than 25 MPa. This suggested that lignins act as adhesives. SAL and HAL sheets with 40% newspaper were strengthened by the carbonization, whereas the strength of other lignin sheets was depressed. Finally, the AL-based AC sheets showed higher flexural strength (>6MPa) than others. Most of the AC sheets had adsorption ability comparable to that of commercially available AC powder and granules. The capacities were almost independent of paper content. Among the AC moldings tested, the AL-based AC sheets showed the fastest adsorption top-chlorophenol. Thus, viable AC moldings can be prepared from lignin-wastepaper mixtures, particularly SAL and HAL.  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