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   406篇
  免费   16篇
  国内免费   1篇
林业   26篇
农学   17篇
基础科学   1篇
  37篇
综合类   25篇
农作物   105篇
水产渔业   44篇
畜牧兽医   145篇
园艺   6篇
植物保护   17篇
  2023年   5篇
  2022年   22篇
  2021年   25篇
  2020年   10篇
  2019年   10篇
  2018年   13篇
  2017年   12篇
  2016年   12篇
  2015年   18篇
  2014年   27篇
  2013年   24篇
  2012年   33篇
  2011年   27篇
  2010年   23篇
  2009年   15篇
  2008年   14篇
  2007年   32篇
  2006年   24篇
  2005年   23篇
  2004年   5篇
  2003年   11篇
  2002年   10篇
  2001年   3篇
  2000年   7篇
  1999年   4篇
  1998年   1篇
  1996年   1篇
  1993年   1篇
  1988年   1篇
  1987年   1篇
  1985年   1篇
  1978年   1篇
  1977年   1篇
  1976年   2篇
  1974年   1篇
  1972年   2篇
  1969年   1篇
排序方式: 共有423条查询结果,搜索用时 22 毫秒
321.
In this study, near-infrared absorbing dyes, namely new rigidified heptamethine cyanines dyes, were synthesized by the reaction of bis-aldehyde-(1-formyl-3-hydroxymethylene)cyclohexene with 1,1,2-trimethylbenzindole derivatives. Two new rigidified heptamethine cyanine dyes were readily prepared by a novel semi-catalyzed method, considering their potential applications for photodynamic therapy. Absorption properties in near-infrared regions may provide these dyes to be applicable in optical recording media, biological fluorescent stains and probes. Synthesis details and full spectroscopic characterizations of the cyanines were described.  相似文献   
322.
An 8-month-old cat was presented with bilateral hydronephrosis. Bilateral ureteral obstructions were identified by diagnostic imaging and confirmed by necropsy. Histopathologic findings revealed polypoid transitional epithelial hyperplasia with chronic lymphoplasmacytic inflammation. This report documents congenital ureteral strictures as a cause of ureteral obstruction in a young cat.  相似文献   
323.
Marine actinobacteria-produced fucoidanases have received considerable attention as one of the major research topics in recent years, particularly for the medical exploitation of fucoidans and their degradation products. The present study describes the optimization and production of a novel fucoidanase for the green synthesis of gold nanoparticles and its biological applications. The production of fucoidanase was optimized using Streptomyces sp. The medium components were selected in accordance with the Plackett-Burman design and were further optimized via response surface methodology. The fucoidanase was statistically optimized with the most significant factors, namely wheat bran 3.3441 g/L, kelp powder 0.7041 g/L, and NaCl 0.8807 g/L, respectively. The biosynthesized gold nanoparticles were determined by UV-vis spectroscopy and were further characterized by X-ray diffraction analysis, Fourier transform infrared spectroscopy, field emission scanning electron microscopy, energy dispersive X-ray analysis, and high-resolution transmission electron microscopy. Furthermore, the biosynthesized gold nanoparticles exhibited a dose-dependent cytotoxicity against HeLa cells and the inhibitory concentration (IC50) was found to be 350 µg/mL at 24 h and 250 µg/mL at 48 h. Therefore, the production of novel fucoidanase for the green synthesis of gold nanoparticles has comparatively rapid, less expensive and wide application to anticancer therapy in modern medicine.  相似文献   
324.
Aquacultured fish are the richest natural source of protein. However, their overproduced biomass is often discarded due to production imbalance, causing considerable losses to the fishery industry. Therefore, it is necessary to utilize surplus fish and add value to overproduced fish. We performed complex enzyme-assisted hydrolysis to determine the correlation between its physical characteristics and anti-hypertensive activity in vitro and in vivo using an SHR model. Protamex-Pepsin assisted hydrolysate from Paralichthys olivaceus (POppH) produced by complex enzyme-assisted hydrolysis contained low-molecular-weight peptides and amino acids with anti-hypertensive activity. POppH regulated blood pressure and serum angiotensin II and angiotensin-I-converting enzyme levels, and histological and ultrasound image analysis revealed substantially reduced thickness and diameter of the carotid aorta in the POppH-administered SHR group. Therefore, we propose to reduce food loss due to overproduction by utilizing the anti-hypertensive activity and physical properties of POppH; the results demonstrate its application as a therapeutic agent.  相似文献   
325.
326.
The spinline behavior in dual nozzle electrospinning was observed using high shutter speed photography and laser scattering technique. It was found that the spinlines of each nozzle have skewed bell shapes. The solution concentration, the number of nozzles, the nozzle-to-nozzle distance (NND) showed significant effects on both the spinline shape and the fiberweb morphology. They were also resulted from the inter- and the intra-spinline repulsive forces. Especially the fibers collected in the middle of the collecting plate were oriented along the tangential direction to the two webs spun from each nozzle.  相似文献   
327.
328.
329.
Neospora caninum is an intracellular apicomplexan parasite that infects a wide range of mammals and has been associated with abortion in cattle worldwide. Artemisinin is an effective antimalarial compound derived from a traditional Chinese herbal remedy, qinghao or Artemisia annua L. In the study reported, the cultured host cells (vero cells or mouse peritoneal macrophages) infected with N. caninum tachyzoites were incubated with alpha-MEM (minimal essential medium) 10%HS supplemented with various concentration or artemisinin (20, 10, 1, 0.1 and 0.01 microg/ml) to examine the efficacy of artemisinin against N. caninum tachyzoites intracellular multiplication. In long-term studies, at 20 or 10 microg/ml for 11 days, artemisinin reduced N. caninum and completely eliminated all microscopic foci of N. caninum. At 1 microg/ml for 14 days, artemisinin reduced N. caninum and completely achieved elimination of all microscopic foci of N. caninum. There was no apparent toxicity to host cells in long-term studies. In short-term studies, at > or = 0.1microg/ml, artemisinin reduced N. caninum tachyzoites intracellular multiplication, significantly (P < 0.05) and appeared to depend on the artemisinin concentrations. Pretreatment of host cells or N. caninum tachyzoites with artemisinin had no effect on N. caninum tachyzoites intracellular multiplication. These results demonstrate that artemisinin inhibited N. caninum tachyzoites intracellular multiplication.  相似文献   
330.
The effect of ginkgo fruit addition on methane production potential of cattle feces and slurry was assessed in relation to other fermentation products and the microbial community. Holstein cattle fresh feces and slurry were left at 30°C for 0, 30, 60, 90, and 180 days with/without ginkgo fruit to monitor the effect on fermentation potential. With the addition of ginkgo fruit, methane production potential of feces was reduced on Day 30 and thereafter, and that of slurry was consistently reduced over the experimental period. As a general trend, ginkgo fruit addition resulted in decreased acetate and increased propionate in feces and acetate accumulation in slurry. With ginkgo fruit addition, MiSeq analyses indicated decreases in methanogen (in particular Methanocorpusculum), Ruminococcaceae, and Clostridiaceae populations and increases in Bacteroidaceae and Porphyromonadaceae populations, which essentially agreed with quantitative real-time polymerase chain reaction (qPCR) assay results. These data indicate that direct addition of ginkgo fruit to cattle excreta is useful for reducing methane emissions by altering the microbial community structure. The application of ginkgo fruit to lower methane emissions from cattle excreta is, therefore, useful in cases in which the excreta is left without special management for a long period of time.  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