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   1978篇
  免费   72篇
  国内免费   6篇
  2024年   1篇
  2023年   23篇
  2022年   75篇
  2021年   137篇
  2020年   85篇
  2019年   89篇
  2018年   97篇
  2017年   85篇
  2016年   102篇
  2015年   144篇
  2014年   162篇
  2013年   163篇
  2012年   149篇
  2011年   130篇
  2010年   85篇
  2009年   73篇
  2008年   99篇
  2007年   72篇
  2006年   59篇
  2005年   61篇
  2004年   53篇
  2003年   28篇
  2002年   37篇
  2001年   4篇
  2000年   1篇
  1999年   2篇
  1997年   3篇
  1996年   4篇
  1995年   5篇
  1994年   5篇
  1993年   1篇
  1992年   2篇
  1991年   1篇
  1989年   2篇
  1987年   1篇
  1983年   3篇
  1982年   2篇
  1981年   2篇
  1980年   2篇
  1976年   1篇
  1975年   1篇
  1972年   1篇
  1964年   2篇
  1962年   1篇
  1961年   1篇
排序方式: 共有2056条查询结果,搜索用时 109 毫秒
31.
Habib  K. A.  Islam  Md. J.  Nahar  N.  Neogi  A. K.  Fraser  T. H. 《Journal of Ichthyology》2021,61(4):505-513
Journal of Ichthyology - Three species of cardinalfishes viz. Ostorhinchus cookii (Macleay, 1881), Lepidamia kalosoma (Bleeker, 1852) and Apogonichthyoides sialis (Jordan et Thompson, 1914)...  相似文献   
32.
This study was undertaken to investigate oxidative stress tolerant mechanisms in chilli (Capsicum annuum L.) under drought genotypes through evaluating morphological, physiological, biochemical and stomatal parameters. Twenty genotypes were evaluated for their genetic potential to drought stress tolerant at seedling stage. Thirty days old seedlings were exposed to drought stress induced by stop watering for the following 10 days and rewatering for the following one week as recovery. Based on their survival performance, two tolerant genotypes viz. BD-10906 and BD-109012 and two susceptible genotypes viz. BD-10902 and RT-20 were selected for studying the oxidative stress tolerance mechanism. Drought reduced root and shoot length, dry weight, ratio, petiole weight and leaf area in both tolerant and susceptible genotypes, and a higher reduction was observed in susceptible genotypes. Lower reduction of leaf area and photosynthetic pigments were also found in tolerant genotypes. Moreover, tolerant genotypes showed higher recovery than susceptible genotypes after the removal of stress. A higher reduction of relative water content (RWC) may cause an imbalance between absorbed and transpirated water in susceptible genotypes. Higher accumulation of proline in tolerant genotypes might be helpful to for better osmotic maintenance than that in susceptible genotypes. Tolerant genotypes showed higher antioxidant activity as they showed DPPH radical scavenging percentage than the susceptible genotypes. Moreover, closer stomata in tolerant genotypes than susceptible ones helped to avoid dehydration in tolerant genotypes. Thus, the above morphological, physiological, biochemical and stomatal parameters helped to show better tolerance in chilli under drought stress.  相似文献   
33.
Plant and Soil - The major factors controlling the soil methane (CH4) concentration and CH4 emissions of various plant (mainly wetland) species were identified. Five plant species (Oryza sativa,...  相似文献   
34.
The length-weight relationships (LWRs) of six Nemacheilid species (Schistura chindwinica, S. fasciata, S. khugae, S. minuta, S. reticulata and S. rubrimaculata) have been analyzed. Fish samples were collected on quarterly basis from March 2018 to February 2019. Sampling was performed using cast nets (mesh size 5–10 mm; about 50 sq m area covered each time and water depth was 4 ft approx.), and electrofishing (Ultrasonic Inverter Electro Fisher, 24 volts, 4 m) in the day time. The total length (TL) of individual fish was measured to 0.1 cm with a digital caliper and body weights (BW) were measured to 0.001 g with digital electronic balances. The parameters for the LWR equations were calculated, and the respective statistics such as the 95% confidence interval for parameters “a” and “b” are provided as well as the coefficient of correlation. For five species a new maximum total length has been documented.  相似文献   
35.
Length weight relationships (LWR) of five marine fishes were estimated from the Bay of Bengal, Bangladesh. Fish samples were collected occasionally from fisher's catch with gill net (mesh size: 3 cm) during November 2019 to October 2020. Fishing was done overnight. Total length (0.1 cm) and body weight (0.01 g) of each individual were measured. We recorded maximum total length for P. maculatus (55.0 cm) and P. parmatus (39.0 cm).  相似文献   
36.
Molecular Biology Reports - Alzheimer's disease is a common neurodegenerative disease in the elderly population and a leading cause of dementia. Genetics and environmental risk factors were...  相似文献   
37.
Amino Acids - The antidiabetic effect of l-leucine has been attributed to its modulatory effect on glucose uptake and lipid metabolism in muscles. However, there is a dearth on its effect on...  相似文献   
38.
Probiotics and Antimicrobial Proteins - The use of in vitro systems that allow efficient selection of probiotic candidates with immunomodulatory properties could significantly minimize the use of...  相似文献   
39.
Probiotics and Antimicrobial Proteins - In this study, a bacterial strain COFCAU_P1, isolated from the digestive tract of a freshwater teleost rohu (Labeo rohita), was identified as Bacillus...  相似文献   
40.
Two series of chalcone/aryl carboximidamide hybrids 4a–f and 6a–f were synthesised and evaluated for their inhibitory activity against iNOS and PGE2. The most potent derivatives were further checked for their in vivo anti-inflammatory activity utilising carrageenan-induced rat paw oedema model. Compounds 4c, 4d, 6c and 6d were proved to be the most effective inhibitors of PGE2, LPS-induced NO production, iNOS activity. Moreover, 4c, 4d, 6c and 6d showed significant oedema inhibition ranging from 62.21% to 78.51%, compared to indomethacin (56.27 ± 2.14%) and celecoxib (12.32%). Additionally, 4c, 6a and 6e displayed good COX2 inhibitory activity while 4c, 6a and 6c exhibited the highest 5LOX inhibitory activity. Compounds 4c, 4d, 6c and 6d fit nicely into the pocket of iNOS protein (PDB ID: 1r35) via the important amino acid residues. Prediction of physicochemical parameters exhibited that 4c, 4d, 6c and 6d had acceptable physicochemical parameters and drug-likeness. The results indicated that chalcone/aryl carboximidamides 4c, 4d, 6c and 6d, in particular 4d and 6d, could be used as promising lead candidates as potent anti-inflammatory agents.  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