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   320篇
  免费   26篇
  国内免费   1篇
  2024年   1篇
  2023年   2篇
  2022年   11篇
  2021年   16篇
  2020年   7篇
  2019年   11篇
  2018年   27篇
  2017年   9篇
  2016年   20篇
  2015年   13篇
  2014年   20篇
  2013年   26篇
  2012年   21篇
  2011年   23篇
  2010年   6篇
  2009年   9篇
  2008年   13篇
  2007年   16篇
  2006年   8篇
  2005年   14篇
  2004年   11篇
  2003年   6篇
  2002年   5篇
  2001年   6篇
  2000年   5篇
  1999年   2篇
  1998年   2篇
  1997年   3篇
  1996年   3篇
  1994年   3篇
  1992年   3篇
  1991年   5篇
  1990年   2篇
  1989年   2篇
  1988年   5篇
  1987年   3篇
  1986年   1篇
  1985年   2篇
  1984年   1篇
  1979年   1篇
  1977年   2篇
  1975年   1篇
排序方式: 共有347条查询结果,搜索用时 31 毫秒
61.
After nitrite treatment, various kinds of pickled vegetables and sun-dried fishes produced in Japan showed direct-acting mutagenicity on Salmonella typhimurium TA100, inducing 1900-18000 revertants/g. Kimchis, sun-dried fishes, sun-dried squid, soy sauces, fish sauces, bean pastes and shrimp paste produced in Korea, the Philippines and Thailand also showed direct-acting mutagenicity after nitrite treatment. All soy sauces and fish sauces tested contained as much tyramine as 17-1020 micrograms/ml, but very low or undetectable amounts of (-)-(1S,3S)- and (-)-(1R,3S)-1-methyl-1,2,3,4-tetrahydro-beta-carboline-3-carboxylic acids.  相似文献   
62.
A strain of Klebsiella pneumoniae that used aliphatic nitriles as the sole source of nitrogen was adapted to benzonitrile as the sole source of carbon and nitrogen. Gas chromatographic and mass spectral analyses of culture filtrates indicated that K. pneumoniae metabolized 8.4 mM benzonitrile to 4.0 mM benzoic acid and 2.7 mM ammonia. In addition, butyronitrile was metabolized to butyramide and ammonia. The isolate also degraded mixtures of benzonitrile and aliphatic nitriles. Cell extracts contained nitrile hydratase and amidase activities. The enzyme activities were higher with butyronitrile and butyramide than with benzonitrile and benzamide, and amidase activities were twofold higher than nitrile hydratase activities. K. pneumoniae appears promising for the bioremediation of sites contaminated with aliphatic and aromatic nitriles.  相似文献   
63.
The present work examined morphological and physiological aspects of osmoregulation in some differently adapted populations of Typha domingensis. Six populations of T. domingensis were grown in waterlogged conditions under four levels of nickel (0, 50, 100 and 1500 mg/kg of Ni). The Ni tolerance was explored on the basis of different characteristics of shoots. Along with the increasing level of Ni stress, all populations showed an increment of proline and glycinebetaine content, low photosynthetic and transpiration rates and decreased chlorophyll content. Analyzed morphological parameters revealed possible adaptations to deal with Ni stress. The less tolerant Sahianwala population produced more aerenchyma, less accumulation of osmolytes and reduced shoot fresh weight under Ni stress than the tolerant ones. Our results suggested that T. domingensis has the capacity to survive under Ni stress and could be used for the absorption of toxic metal ions from industrially polluted water.  相似文献   
64.
65.
This overview groups some of the recent studies highlighting the potential application of Raman microspectroscopy as an analytical technique in preclinical development to predict drug mechanism of action and in clinical application as a companion diagnostic and in personalised therapy due to its capacity to predict cellular resistance and therefore to optimise chemotherapeutic treatment efficacy. Notably, the anthracyclines, doxorubicin and actinomycin D, elicit similar spectroscopic signatures of subcellular interaction characteristic of the mode of action of intercalation. Although cisplatin and vincristine show markedly different signatures, at low exposure doses, their signatures at higher doses show marked similarities to those elicited by the intercalating anthracyclines, confirming that anticancer agents can have different modes of action with different spectroscopic signatures, depending on the dose. The study demonstrates that Raman microspectroscopy can elucidate subcellular transport and accumulation pathways of chemotherapeutic agents, characterise and fingerprint their mode of action, and potentially identify cell‐resistant strains. The consistency of the spectroscopic signatures for drugs of similar modes of action, in different cell lines, suggests that this fingerprint can be considered a “spectralome” of the drug‐cell interaction suggesting a new paradigm of representing spectroscopic responses.   相似文献   
66.
Journal of Plant Growth Regulation - Plants face different types of biotic and abiotic stresses during their life span. Heavy metal (HM) stress is considered as one of the most challenging and...  相似文献   
67.
68.
Chili pepper (Capsicum annum L.) is an important economic crop that is severely destroyed by the filamentous oomycete Phytophthora capsici. Little is known about this pathogen in key chili pepper farms in Punjab province, Pakistan. We investigated the genetic diversity of P. capsici strains using standard taxonomic and molecular tools, and characterized their colony growth patterns as well as their disease severity on chili pepper plants under the greenhouse conditions. Phylogenetic analysis based on ribosomal DNA (rDNA), β-tubulin and translation elongation factor 1α loci revealed divergent evolution in the population structure of P. capsici isolates. The mean oospore diameter of mating type A1 isolates was greater than that of mating type A2 isolates. We provide first evidence of an uneven distribution of highly virulent mating type A1 and A2 of P. capsici that are insensitive to mefenoxam, pyrimorph, dimethomorph, and azoxystrobin fungicides, and represent a risk factor that could ease outpacing the current P. capsici management strategies.  相似文献   
69.
Four series of heterocyclic compounds, namely, tetrahydro-2H-1,3,5-thiadiazine thione derivatives were synthesized in good to excellent yields and were screened for their in vitro antileishmanial activities against Leishmania major (promastigotes). Most of the compounds showed significant antileishmanial activity within the range of IC50?=?15.48–39.36?μM when compared with standard pentamidine (IC50?=?14.95?μM). The structure-activity relationship showed that N-3 and N-5 substituents have a key role against leishmanicidal activity. The ester analogues (series B) were found to have a 1.5 to 5-fold reduced activity compared to their acidic counterparts. Cytotoxicity against mammalian mouse fibroblast 3?T3 cells was also evaluated and compared between the acid and its ester analogue. The reduction of antileishmanial activity and loss of toxicity in the newly developed THTT ester derivative indicates that these compounds can be used as a template study for the production of effective antileishmanial ester prodrugs.  相似文献   
70.
The prime objective of this research work is to prepare readily soluble synthetic analogues of naturally occurring 3-O-flavonol glycosides and then investigate the influence of various substituents on biological properties of synthetic compounds. In this context, a series of varyingly substituted 3-O-flavonol glycosides have been designed, synthesized and characterized efficiently. The structures of synthetic molecules were unambiguously corroborated by IR, 1H, 13C NMR and ESI-MS spectroscopic techniques. The structure of compound 22 was also analyzed by X-ray diffraction analysis. All the synthetic compounds (2130) were evaluated for in vitro inhibitory potential against cholinesterase enzymes. The results displayed that most of the derivatives were potent inhibitors of acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) with varying degree of IC50 values. The experimental results were further encouraged by molecular docking studies in order to explore their binding behavior with the active pocket of AChE and BChE enzymes. The experimental and theoretical results are in parallel with one another.  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