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   1660篇
  免费   118篇
  国内免费   353篇
  2023年   34篇
  2022年   37篇
  2021年   49篇
  2020年   62篇
  2019年   71篇
  2018年   53篇
  2017年   63篇
  2016年   62篇
  2015年   74篇
  2014年   81篇
  2013年   103篇
  2012年   56篇
  2011年   93篇
  2010年   66篇
  2009年   84篇
  2008年   112篇
  2007年   107篇
  2006年   77篇
  2005年   65篇
  2004年   73篇
  2003年   59篇
  2002年   55篇
  2001年   51篇
  2000年   50篇
  1999年   47篇
  1998年   44篇
  1997年   38篇
  1996年   28篇
  1995年   43篇
  1994年   38篇
  1993年   34篇
  1992年   25篇
  1991年   14篇
  1990年   19篇
  1989年   18篇
  1988年   5篇
  1987年   8篇
  1986年   6篇
  1985年   19篇
  1984年   19篇
  1983年   10篇
  1982年   9篇
  1981年   7篇
  1980年   9篇
  1979年   12篇
  1978年   8篇
  1977年   7篇
  1976年   8篇
  1975年   4篇
  1974年   8篇
排序方式: 共有2131条查询结果,搜索用时 15 毫秒
1.
Folsomia Candida was maintained on potato dextrose agar (PDA) plates precolonised by the mycoparasite Coniothyrium minitans for 3 yr but the sciarid Bradysia sp. survived for a maximum of only three generations. Collembolans and sciarid larvae from these cultures were able to transmit C. minitans to uninoculated PDA plates through the survival of spores in faecal pellets. Adult and larval sciarids also transmitted C. minitans from PDA culture to uninoculated PDA plates by contamination on the cuticle. In soil and sand both sciarids and collembolans were able to transmit C. minitans from C. m/m'tans-inoculated to uninoculated sclerotia of Sclerotinia sclerotiorum. Inoculation of sclerotia with C. minitans enabled greater populations of larger collembolans to develop. In the glasshouse where C. minitans had been applied to the soil, one adult sciarid and four collembolans out of 70 and 101 insects collected respectively yielded C. minitans on placement onto PDA + Aureomycin.  相似文献   
2.
The lipid composition of swimming spores, cysts and five hour germlings was established. Spores utilized triglycerides first, then phospholipids. Upon encystment all glycolipid components decreased, while in germlings the phospholipids, monoglycerides and sterol esters exhibited a marked increase.  相似文献   
3.
Time course studies of carotenoid production and of mycelial growth in liquid cultures of Phycomyces blakesleeanus wild type [NRRL 1555 (?)], red mutants C9, C10 and C13 and the heterokaryon C2 * C9 are reported. The ratios of the concentrations of lycopene, γ-carotene and β-carotene in the red mutant C13 and in the heterokaryon C2 * C9 during the growth periods were measured. In these strains the concentration of lycopene is close to its final value after 2 days of growth, at a time at which β-carotene is just beginning to be produced. It is suggested that the β-carotene produced late is possibly synthesized via β-zeacarotene.  相似文献   
4.
5.
6.
Three new dihydroisocoumarin derivatives, penicisimpins A⿿C (1⿿3), were isolated and identified from Penicillium simplicissimum MA-332, a fungus derived from the rhizosphere of the marine mangrove plant Bruguiera sexangula var. rhynchopetala. Their structures and absolute configurations were elucidated by extensive spectroscopic methods in combination with X-ray diffraction experiment. Compounds 1⿿3 exhibited brine shrimp (Artemia salina) lethality as well as broad-spectrum antimicrobial activities.  相似文献   
7.
A qualitative bioassay was developed with Macrophomina phaseoli (Maubl.) Ashby to assess photosporogenic activity of different fatty acid fractions  相似文献   
8.
A total of 120 fungal strains were isolated from soil samples and evaluated in the bioreduction of substituted acetophenones to the corresponding (R)‐alcohols. Among these strains, isolate Trichothecium roseum EBK‐18 was highly effective in the production of (R)‐alcohols with excellent enantioselectivity (ee > 99%). Gram scale preparation of (R)‐1‐phenylethanol is reported. Chirality 2010. © 2009 Wiley‐Liss, Inc.  相似文献   
9.
Marine derived fungus has gained increasing ground in the discovery of novel lead compounds with potent biological activities including anti-inflammation. Here, we first report the characterization of one new sorbicillinoid ( 1 ) and fourteen known compounds ( 2 – 15 ) from the ethyl acetate (AcOEt) extract of a cultured mangrove derived fungus Penicillium sp. DM815 by UV, IR, HR ESI-Q-TOF MS, and NMR spectra. We then evaluated the anti-inflammatory effects of eleven sorbicillinoids ( 1 – 11 ) using cultured macrophage RAW264.7 cells. The results show that compound 9 , and to a lesser degree compound 5 , significantly inhibited the Gram-negative bacteria lipopolysaccharide (LPS)-induced upregulation of the inducible nitric oxide synthase (iNOS). Consistently, compounds 5 and 9 significantly reduced the level of nitric oxide (NO), the product of iNOS, induced by LPS. We further show that these two compounds dose-dependently inhibited LPS-triggered iNOS expression and NO production, but had no effect on proliferation of RAW264.7 cells in the presence of LPS. In conclusion, our study identifies novel and known sorbicillinoids as potent anti-inflammatory agents, holding the promise of developing novel anti-inflammation treatment in the future.  相似文献   
10.
The racemate and the enantiomers of cytosporone E [3-heptyl-4,5,6-trihydroxyphthalide (1)], a metabolite of the endophytic fungus, CR200 (Cytospora sp.), were synthesized. The key steps were (i) Sharpless asymmetric dihydroxylation of an alkene (8) and (ii) HPLC separation of the enantiomers of tert-butyldimethylsilyl ether (12) on a chiral stationary phase. The racemate and enantiomers of cytosporone E showed only weak antimicrobial activity with no difference among them.  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