全文获取类型
收费全文 | 464篇 |
免费 | 21篇 |
出版年
2024年 | 1篇 |
2023年 | 3篇 |
2022年 | 13篇 |
2021年 | 19篇 |
2020年 | 11篇 |
2019年 | 12篇 |
2018年 | 19篇 |
2017年 | 22篇 |
2016年 | 21篇 |
2015年 | 23篇 |
2014年 | 31篇 |
2013年 | 34篇 |
2012年 | 54篇 |
2011年 | 39篇 |
2010年 | 17篇 |
2009年 | 6篇 |
2008年 | 16篇 |
2007年 | 19篇 |
2006年 | 25篇 |
2005年 | 18篇 |
2004年 | 16篇 |
2003年 | 2篇 |
2002年 | 14篇 |
2001年 | 3篇 |
2000年 | 1篇 |
1999年 | 3篇 |
1998年 | 3篇 |
1997年 | 2篇 |
1996年 | 3篇 |
1995年 | 5篇 |
1994年 | 4篇 |
1993年 | 2篇 |
1992年 | 3篇 |
1991年 | 2篇 |
1989年 | 1篇 |
1988年 | 3篇 |
1987年 | 2篇 |
1985年 | 1篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1978年 | 2篇 |
1977年 | 4篇 |
1976年 | 1篇 |
1974年 | 2篇 |
1973年 | 1篇 |
排序方式: 共有485条查询结果,搜索用时 19 毫秒
101.
Microalgae as multi-functional options in modern agriculture: current trends,prospects and challenges 总被引:2,自引:0,他引:2
Nirmal Renuka Abhishek Guldhe Radha Prasanna Poonam Singh Faizal Bux 《Biotechnology advances》2018,36(4):1255-1273
Algae are a group of ubiquitous photosynthetic organisms comprising eukaryotic green algae and Gram-negative prokaryotic cyanobacteria, which have immense potential as a bioresource for various industries related to biofuels, pharmaceuticals, nutraceuticals and feed. This fascinating group of organisms also has applications in modern agriculture through facilitating increased nutrient availability, maintaining the organic carbon and fertility of soil, and enhancing plant growth and crop yields, as a result of stimulation of soil microbial activity. Several cyanobacteria provide nitrogen fertilization through biological nitrogen fixation and through enzymatic activities related to interconversions and mobilization of different forms of nitrogen. Both green algae and cyanobacteria are involved in the production of metabolites such as growth hormones, polysaccharides, antimicrobial compounds, etc., which play an important role in the colonization of plants and proliferation of microbial and eukaryotic communities in soil. Currently, the development of consortia of cyanobacteria with bacteria or fungi or microalgae or their biofilms has widened their scope of utilization. Development of integrated wastewater treatment and biomass production systems is an emerging technology, which exploits the nutrient sequestering potential of microalgae and its valorisation. This review focuses on prospects and challenges of application of microalgae in various areas of agriculture, including crop production, protection and natural resource management. An overview of the recent advances, novel technologies developed, their commercialization status and future directions are also included. 相似文献
102.
Higher expression of human telomerase reverse transcriptase in productively‐infected CD4 cells possibly indicates a mechanism for persistence of the virus in HIV infection 下载免费PDF全文
103.
Poonam?Yadav Ravdeep?Kaur Mukesh?Kumar?Kanwar Renu?BhardwajEmail author Geetika?Sirhindi Leonard?Wijaya M.?N.?Alyemeni Parvaiz?AhmadEmail author 《Journal of Plant Growth Regulation》2018,37(2):575-590
The transition metal elements like copper act as double-edged sword for living cells. Cu, a redox active metal, is essential for various biological processes, but at higher concentrations it leads to toxicity by inducing production of reactive oxygen species (ROS). Thus, the objective of the present study was to investigate the effects of exogenously applied castasterone on oxidative stress markers and redox homeostasis managers in Brassica juncea plants subject to copper stress for 30 days. Copper-exposed plants showed accumulation of free radicals (H2O2 and superoxide anion) and lipid peroxidation. However, the exogenous treatment of seeds via the seed soaking method with different concentrations of castasterone reduced H2O2 production, superoxide anion radical content, and lipid peroxidation, thus indicating improved detoxification of ROS. Enzyme activity was increased by 19.19% for guaiacol peroxidase, 16.20% for superoxide dismutase, 35.74% for glutathione peroxidase, 27.58% for dehydroascorbate reductase, and 42.75% for ascorbate peroxidase, with castasterone pre-soaking under copper stress. The levels of non-enzymatic antioxidants were also increased with castasterone pre-treatment under copper stress. It may be concluded that castasterone treatment enhanced redox homeostasis managers in addition to increased levels of osmoprotectants. 相似文献
104.
Protective antigen (PA) is the binding component of anthrax lethal toxin produced by Bacillus anthracis, and constitutes a major ingredient of the vaccine against anthrax. PA and lethal factor when added together are cytolytic to mouse macrophages and J774G8 macrophage cell line. This in vitro lethal toxicity assay is very useful in understanding the molecular mechanism of action of lethal toxin. Effective utilization of PA is, however, hampered due to its thermolability. On prolonged storage at 37 ° C, PA was found to lose its activity almost completely. The effect of solvent additives like trehalose, sorbitol, xylitol, sodium citrate and magnesium sulphate on the thermal stabilization of PA was examined. The results indicated an increase in the stability of PA when the incubation at 37 ° C was carried out in the presence of solvent additives used in the 1–3 M range. Magnesium sulphate helped retain the activity up to 82.7% against the control in which no additive was used, as judged by cytolytic assay using J774G8 macrophage cell line. Trehalose or sodium citrate also showed an appreciable protection of PA activity, while sorbitol or xylitol were not very effective. Competitive binding assay using radiolabeled PA showed that PA had lost capacity of binding to macrophage cells on prolonged incubation at 37 ° C. Circular dichroism results at 4, 18 and 37 ° C indicated an increase in secondary structure at 37 ° C relative to that at 4 or 18 ° C, supporting the activity data. 相似文献
105.
Photosynthetic acclimation to elevated CO2 in wheat cultivars 总被引:2,自引:0,他引:2
Wheat (T. aestivum) cvs. Kalyansona and Kundan grown under atmospheric (CA) and elevated CO2 concentrations (650±50 cm3 m-3 - CE) in open top chambers were examined for net photosynthetic rate (PN), stomatal limitation (l
s) of P
N, ribulose-1,5-bisphosphate carboxylase (RuBPC) activity, and saccharide content of the leaves. The P
N values of both CA- and CE-grown plants compared at the same CO2 concentration showed a down regulation under CE at the post-anthesis stage. The negative acclimation of P
N appeared to be due to both stomatal and mesophyll components, and the RuBPC activity got also adjusted. There was a decrease
in activation state of RuBPC under CE. In connection with this, an increased accumulation of saccharides in wheat leaf under
CE was observed. Kalyansona, owing to its larger sink potential in terms of the number of grains, showed a greater enhancement
under CE in both post-ear emergence dry matter production and grain yield. Under CE, this cultivar also showed a lower down
regulation of P
N than Kundan.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
106.
107.
Complete Nucleotide Sequence of Ageratum enation virus and an Alphasatellite Infecting a New Host Glycine max in India 下载免费PDF全文
Shivani Sharma Lakhmir Singh Poonam Roshan Aditya Kulshreshtha Nageswar Singh Vipin Hallan 《Journal of Phytopathology》2016,164(7-8):554-557
During 2011, leaf crumpling, yellowing and stunting were observed on soya bean (Glycine max) in Himachal Pradesh, India. PCR‐based detection confirmed the presence of a begomovirus. The viral genome was amplified by rolling circle amplification, cloned and sequenced. The complete nucleotide sequence of DNA‐A showed highest nucleotide identity to an isolate of Ageratum enation virus infecting a weed Ageratum conyzoides. In addition, a DNA molecule was found which shared 95% nucleotide identity with an alphasatellite infecting ageratum. Neither beta satellite nor DNA‐B was detected in the infected samples. 相似文献
108.
Vanila Sharma Paresh Sharma Angamuthu Selvapandiyan Poonam Salotra 《Molecular microbiology》2016,99(3):597-610
Protein modification by ubiquitin (Ub) and Ub‐like molecules (Ubls) is a diverse biological process that regulates the activity of the target proteins. Systematic studies of Ubls in trypanosomatids like Leishmania, the causative organism of potentially fatal visceral leishmaniasis, would yield a better understanding of the disease pathogenesis and identify novel therapeutic targets. The present study is the first to characterize Leishmania donovani‐specific Ub‐related modifier‐1 (LdUrm1) and the associated conjugation pathway. Based on homology modeling, LdUrm1 was found to possess a β‐grasp fold and a C‐terminal di‐glycine motif unique to Ub/Ubls, essential for its conjugation to the target proteins. We identified LdUba4 as the E1 enzyme for LdUrm1 and demonstrated its energy‐dependent enzymatic activity. LdUrm1 was immunolocalized anteriorly near the flagellar reservoir, while LdUba4 was cytoplasmic, both in promastigotes and axenic amastigotes. Expression of nonconjugatable LdUrm1 in L. donovani resulted in depleted parasite growth suggesting its role in the pathogenesis. By mass spectrometry, we identified Rab5, a known mediator of early endosome regulated hemoglobin endocytosis in Leishmania, as a target of LdUrm1. Our data suggest that LdUrm1 conjugation pathway may have a role in early endosome‐mediated heme uptake in Leishmania that may be explored as a drug target. 相似文献
109.
New efficient catalysts based on electrophilic N‐fluoro quaternary ammonium salts are reported for catalytic allylation of (E)‐N,1‐diphenylmethanimine. The chiral version of the catalyst based on cinchonidine (F‐CD‐BF4) shows high catalytic activity with approximately 94% ee and TOF (>800 h?1). The F‐CD‐BF4 is prepared from cinchonidine and Selectfluor by one‐step transfer fluorination. 相似文献
110.
Yadav Manisha Shivani Misra Alka Tandon Poonam 《Origins of life and evolution of the biosphere》2019,49(1-2):89-103
Origins of Life and Evolution of Biospheres - The Structure of carbodiimide has been studied by using quantum chemical methods. Carbodiimide (HNCNH) has been detected towards Sagittarius B2 (N) in... 相似文献