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   524篇
  免费   39篇
  国内免费   4篇
  567篇
  2023年   5篇
  2022年   12篇
  2021年   13篇
  2020年   11篇
  2019年   18篇
  2018年   16篇
  2017年   9篇
  2016年   32篇
  2015年   35篇
  2014年   37篇
  2013年   28篇
  2012年   37篇
  2011年   34篇
  2010年   22篇
  2009年   14篇
  2008年   37篇
  2007年   34篇
  2006年   25篇
  2005年   19篇
  2004年   25篇
  2003年   13篇
  2002年   8篇
  2001年   10篇
  2000年   7篇
  1999年   3篇
  1998年   7篇
  1997年   6篇
  1996年   4篇
  1994年   1篇
  1993年   2篇
  1992年   6篇
  1991年   2篇
  1990年   3篇
  1989年   2篇
  1988年   3篇
  1987年   7篇
  1986年   3篇
  1985年   1篇
  1984年   2篇
  1983年   4篇
  1982年   4篇
  1979年   1篇
  1978年   1篇
  1970年   1篇
  1963年   1篇
  1931年   2篇
排序方式: 共有567条查询结果,搜索用时 0 毫秒
51.
52.
53.
The ant‐plant Humboldtia brunonis secretes extrafloral nectar (EFN) despite the lack of antiherbivore protection from most ants. EFN was richer in composition than phloem sap and honeydew from untended Hemiptera on the plant, suggesting that EFN could potentially distract ants from honeydew, since ants rarely tended Hemiptera on this plant.  相似文献   
54.
We previously reported that i) a Western diet increased levels of unsaturated lysophosphatidic acid (LPA) in small intestine and plasma of LDL receptor null (LDLR−/−) mice, and ii) supplementing standard mouse chow with unsaturated (but not saturated) LPA produced dyslipidemia and inflammation. Here we report that supplementing chow with unsaturated (but not saturated) LPA resulted in aortic atherosclerosis, which was ameliorated by adding transgenic 6F tomatoes. Supplementing chow with lysophosphatidylcholine (LysoPC) 18:1 (but not LysoPC 18:0) resulted in dyslipidemia similar to that seen on adding LPA 18:1 to chow. PF8380 (a specific inhibitor of autotaxin) significantly ameliorated the LysoPC 18:1-induced dyslipidemia. Supplementing chow with LysoPC 18:1 dramatically increased the levels of unsaturated LPA species in small intestine, liver, and plasma, and the increase was significantly ameliorated by PF8380 indicating that the conversion of LysoPC 18:1 to LPA 18:1 was autotaxin dependent. Adding LysoPC 18:0 to chow increased levels of LPA 18:0 in small intestine, liver, and plasma but was not altered by PF8380 indicating that conversion of LysoPC 18:0 to LPA 18:0 was autotaxin independent. We conclude that i) intestinally derived unsaturated (but not saturated) LPA can cause atherosclerosis in LDLR−/− mice, and ii) autotaxin mediates the conversion of unsaturated (but not saturated) LysoPC to LPA.  相似文献   
55.
56.

Background

Phylogenetic-based classification of M. tuberculosis and other bacterial genomes is a core analysis for studying evolutionary hypotheses, disease outbreaks and transmission events. Whole genome sequencing is providing new insights into the genomic variation underlying intra- and inter-strain diversity, thereby assisting with the classification and molecular barcoding of the bacteria. One roadblock to strain investigation is the lack of user-interactive solutions to interrogate and visualise variation within a phylogenetic tree setting.

Results

We have developed a web-based tool called PhyTB (http://pathogenseq.lshtm.ac.uk/phytblive/index.php) to assist phylogenetic tree visualisation and identification of M. tuberculosis clade-informative polymorphism. Variant Call Format files can be uploaded to determine a sample position within the tree. A map view summarises the geographical distribution of alleles and strain-types. The utility of the PhyTB is demonstrated on sequence data from 1,601 M. tuberculosis isolates.

Conclusion

PhyTB contextualises M. tuberculosis genomic variation within epidemiological, geographical and phylogenic settings. Further tool utility is possible by incorporating large variants and phenotypic data (e.g. drug-resistance profiles), and an assessment of genotype-phenotype associations. Source code is available to develop similar websites for other organisms (http://sourceforge.net/projects/phylotrack).  相似文献   
57.
A partial nitrification system was investigated for 471 days under DO varying concentrations for assessing its stability and population dynamics. Within 130 days of operation at feed DO concentration of 1.0 ± 0.1 mg/L, more than 85% of nitrite was accumulated. Efficiency deteriorated when the feed DO concentration was increased to 4.2 ± 0.3 mg/L. Nitrite accumulation could not be re-established on decreasing feed DO to 1.0 ± 0.1 mg/L. Even at DO concentration of <0.05 mg/L, nitrate production was observed; a condition termed as anoxic nitrification. NOB was detected in the biomass even under this condition by Fluorescence in-situ hybridization (FISH) analysis. Through 16S rRNA gene sequencing a major fraction of unknown bacterial sequences closely resembling haloalkalophilic bacteria of marine origin were detected. The study indicated that these bacterial species might play a role in anoxic nitrification and that NOB could survive extreme low DO condition.  相似文献   
58.
In this study, thermo-adapted (Ta) PPR vaccines were assessed for their stability at 25, 37, 40, 42 and 45°C in lyophilized form using two extrinsic stabilizers {lactalbumin hydrolysate-sucrose (LS) and stabilizer E} and in reconstituted form with the diluents (1 mol/L MgSO4 or 0.85% NaCl). The lyophilized vaccines showed an expiry period of 24–26 days at 25°C, 7–8 days at 37°C and 3–4 days at 40°C. LS stabilizer was superior at 42°C with a shelf-life of 44 h, whereas in stabilizer E, a 40 h shelf-life with a comparable half-life was observed. At 45°C, the half-life in stabilizer E was better than LS and lasted for 1 day. Furthermore, the reconstituted vaccine maintained the titre for 48 h both at 4°C and 25°C and for 24–30 h at 37°C. As both the stabilizers performed equally well with regard to shelf-life and half-life, the present study suggests LS as stabilizer as a choice for lyophilization with 0.85% NaCl diluent, because it has better performance at higher temperature. These Ta vaccines can be used as alternatives to existing vaccines for the control of the disease in tropical countries as they are effective in avoiding vaccination failure due to the breakdown in cold-chain maintenance, as this vaccine is considerably more stable at ambient temperatures.  相似文献   
59.
60.
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