全文获取类型
收费全文 | 204篇 |
免费 | 15篇 |
专业分类
219篇 |
出版年
2024年 | 1篇 |
2022年 | 10篇 |
2021年 | 10篇 |
2020年 | 5篇 |
2019年 | 2篇 |
2018年 | 11篇 |
2017年 | 5篇 |
2016年 | 4篇 |
2015年 | 17篇 |
2014年 | 11篇 |
2013年 | 18篇 |
2012年 | 14篇 |
2011年 | 16篇 |
2010年 | 16篇 |
2009年 | 10篇 |
2008年 | 5篇 |
2007年 | 10篇 |
2006年 | 6篇 |
2005年 | 1篇 |
2004年 | 2篇 |
2003年 | 3篇 |
2002年 | 2篇 |
2001年 | 1篇 |
1999年 | 5篇 |
1998年 | 2篇 |
1997年 | 5篇 |
1996年 | 2篇 |
1994年 | 4篇 |
1993年 | 1篇 |
1992年 | 4篇 |
1990年 | 1篇 |
1988年 | 5篇 |
1986年 | 1篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1981年 | 1篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1975年 | 1篇 |
1972年 | 2篇 |
1971年 | 1篇 |
排序方式: 共有219条查询结果,搜索用时 0 毫秒
61.
All biotic species, including humans, requires energy for their survival and obtained from the process of metabolism. Present work deals with the thermodynamic analysis of the metabolic process of humans and establishes the relation for entropy generation. Further, this entropy generation is linked with the thermodynamics life cycle assessment of humans. Data used in this work is provided by the National sample survey office (NSSO), Government of India. Entropy generation is determined on the bases of per kg of carbohydrate, palmitic acid and 20 amino acids. Finally, the life span of humans has been determined on the grounds of the entropy generation. Entropy generated by Haryana people is maximum in all states, and Tamilnadu people have the minimum among all the states. Total entropy production for Haryana is 23.59 kJ/K-kg-food and for Tamilnadu 19.71 kJ/K-kg-food. People living in Haryana has a life span of 66 years, and Tamilnadu people have a life span of 79 years. The life span for other states ranging in 66–79 years. Variation of ±3% is recorded in the life span of people when compared with the NITI Aayog report. There is a minor difference of 1.22 years in case of life expectancy of Kerla when compared to the NITI Aayog report. In current research work effect of water and air, inhalation is not considered. So one can think these parameters and analyze the variation of the result. 相似文献
62.
Binod P Sukumaran RK Shirke SV Rajput JC Pandey A 《Journal of applied microbiology》2007,103(5):1845-1852
AIMS: To evaluate the biocontrol efficacy of culture filtrate containing chitinase from Trichoderma harzianum against Heliothis. METHODS AND RESULTS: T. harzianum was cultured by submerged fermentation using colloidal chitin as sole carbon source. The ability of the culture filtrate to hydrolyse colloidal chitin indicated the presence of chitinase as one of its components. Biocontrol assay on Heliothis showed that the culture filtrate is a potent antifeedant as it reduced the feeding rate and body weight of the larvae. It reduced the successful pupation and increased larval and pupal mortality in a dosage-dependent manner when applied topically. The highest mortalities (70%) were recorded for groups treated with 2000 U ml(-1) chitinase activity. The percentage of adult emergence was zero for the highest chitinase concentration (2000 U ml(-1)) tried. CONCLUSIONS: The studies showed that the culture filtrate containing chitinase from T. harzianum is capable of negatively affecting the growth and metamorphosis of Heliothis larvae. SIGNIFICANCE AND IMPACT OF THE STUDY: In view of the need for safer and environmentally friendly pest management tools, the present study could help in the development of enzyme-based biopesticides against Heliothis. 相似文献
63.
64.
KATALIN É. SZABÓ JUDIT MAKK KEVE TIHAMÉR KISS ALEXANDER EILER ÉVA ÁCS BENCE TÓTH ÁRON KEVE KISS STEFAN BERTILSSON 《Freshwater Biology》2008,53(7):1359-1371
1. An artificial glass substratum was incubated in the River Danube for a period of 28 days in order to detect the sequential colonization of microorganisms.
2. Light and fluorescent microscopy showed that microalgae and the picoalgal fraction on the slides increased rapidly over the first 2 weeks of colonization. Diatoms were numerically the most abundant component of the periphyton and their species richness and diversity increased rapidly in the early phase of colonization whereas diversity subsequently increased moderately.
3. Evenness of the diatom community was initially high, lower in the intermediate phase and again higher later on. Succession involving early, intermediate and late colonizer species was observed. Community composition during the first 5 days of colonization was very different from later stages whereas there were only minor changes subsequently.
4. Molecular community analysis by means of terminal restriction fragment length polymorphism analysis of PCR amplified 16S rRNA and 18S rRNA genes pointed to even larger differences between the composition of samples obtained early and late in the period.
5. The number of 18S rRNA and 16S rRNA terminal restriction fragments (T-RF-s) was variable over the colonization period and the fragment patterns of both the bacterial and eukaryotic portion of the microbial community were variable, with most T-RF-s unique to a single sample, suggesting a wide diversity and dynamic properties of periphytic organisms. 相似文献
2. Light and fluorescent microscopy showed that microalgae and the picoalgal fraction on the slides increased rapidly over the first 2 weeks of colonization. Diatoms were numerically the most abundant component of the periphyton and their species richness and diversity increased rapidly in the early phase of colonization whereas diversity subsequently increased moderately.
3. Evenness of the diatom community was initially high, lower in the intermediate phase and again higher later on. Succession involving early, intermediate and late colonizer species was observed. Community composition during the first 5 days of colonization was very different from later stages whereas there were only minor changes subsequently.
4. Molecular community analysis by means of terminal restriction fragment length polymorphism analysis of PCR amplified 16S rRNA and 18S rRNA genes pointed to even larger differences between the composition of samples obtained early and late in the period.
5. The number of 18S rRNA and 16S rRNA terminal restriction fragments (T-RF-s) was variable over the colonization period and the fragment patterns of both the bacterial and eukaryotic portion of the microbial community were variable, with most T-RF-s unique to a single sample, suggesting a wide diversity and dynamic properties of periphytic organisms. 相似文献
65.
Reeta Sharma Heiko Stuckas Ranjana Bhaskar Sandeep Rajput Imran Khan Surendra Prakash Goyal Ralph Tiedemann 《Conservation Genetics》2009,10(4):909-914
We analyzed mtDNA polymorphisms (parts of control region, ND5, ND2, Cytb, 12S, together 902 bp) in 59 scat and 18 tissue samples from 13 Indian populations of the critically endangered Indian tiger
(Panthera tigris tigris), along with zoo animals as reference. Northern tiger populations exhibit two unique haplotypes suggesting genetic isolation.
Western populations from Sariska (extinct in 2004) and Ranthambore are genetically similar, such that Ranthambore could serve
as a source for reintroduction in Sariska. Zoo populations maintain mitochondrial lineages that are rare or absent in the
wild. 相似文献
66.
Rishi K. Somvanshi Sabina Billova Geetanjali Kharmate Padmesh S. Rajput Ujendra Kumar 《Cellular signalling》2009,21(9):1396-1414
Somatostatin receptors show great diversity in response to agonist mediated receptor-specific homo- and heterodimerizations. Here, using photobleaching-fluorescence resonance energy transfer, immunocytochemistry, western blot and co-immunoprecipitation, we investigated dimerization, trafficking, coupling to adenylyl cyclase and signaling of human somatostatin receptor-4 (hSSTR4) in HEK-293 cells. We also determined the role of the C-tail of hSSTR4 on physiological responses of the cells. wt-hSSTR4 exogenously expressed in HEK-293 cells exhibits constitutive dimerization, inhibits forskolin-stimulated cAMP, and displays agonist dependent changes in pERK1/2 and pERK5 expressions. Upon C-tail deletion, the receptor loses membrane expression and ability to dimerize and inhibition of cAMP and pERK5 however, displays several-fold increases in the expression of pERK1/2. Chimeric hSSTR4 with the C-tail of hSSTR5 functions like wt-hSSTR4, in contrast, with the C-tail of hSSTR1 functions like C-tail deleted hSSTR4. hSSTR4 dimerization and signaling are associated with increased cyclin-dependent-kinase p27kip1 expression and inhibition of the cell proliferation. We also report heterodimerization between hSSTR4/hSSTR5, but not between hSSTR4/hSSTR1, with significant changes in receptor functions. Taken together, these data define a novel mechanism for the role of hSSTR4 in cell proliferation and modulation of signaling pathways. 相似文献
67.
S. Malhotra A. K. Pandey Y. S. Rajput R. Sharma 《Journal of molecular recognition : JMR》2014,27(8):493-500
In the present work, aptamers against aflatoxin M1 and aflatoxin B1 were generated and tested for creating proof of principle of recognition of aflatoxin M1 by generated aptamers. The aptamers were selected through the process referred as systematic evolution of ligands by exponential enrichment. A total of 41 different aptamer (36 aptamers for aflatoxin M1 and 5 for aflatoxin B1) sequences were obtained. The determination of dissociation constant (Kd) values revealed that aptamers generated against aflatoxin M1 exhibited Kd values in the range of 35–1515 nM. Selected aptamers were grouped on the basis of the presence of common motifs or G‐quadruplex. We find it interesting that one aptamer with no conserved motif or G‐quadruplex had lowest Kd value (Kd = 35 nM). This structural motif is very distinct from motifs present in other aptamers. The Kd values of selected aptamers for aflatoxin B1 were in the range of 96–221 nM. One aptamer from each group was further tested for its ability to be used in aptasensor. The aptamer recognized aflatoxin M1 as indicated by color change (red to purple or blue) of aptamer‐coated gold nanoparticles in the presence of 250–500 nM aflatoxin M1. The aptamers can be used in developing methods for detection/estimation/separation of aflatoxin or antidote for aflatoxin toxicity. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
68.
Siddiqui BS Rasheed M Ilyas F Gulzar T Tariq RM Naqvi SN 《Zeitschrift für Naturforschung. C, Journal of biosciences》2004,59(1-2):104-112
As a result of chemical investigation on the ethanolic extract of fresh fruit coatings of Azadirachta indica A. Juss. (neem), twenty-seven compounds were identified in non-polar to less polar fractions which showed pesticidal activity determined by WHO method against Anopheles stephensi Liston. These identifications were basically made through GC-EIMS and were further supported by other spectroscopic techniques, including 13C NMR, UV and FTIR as well as retention indices. Thus sixteen n-alkanes, 1-16; three aromatics 2,6-bis-(1,1-dimethylethyl)-4-methyl phenol (17), 2-(phenylmethylene)-octanal (20), 1,2,4-trimethoxy-5-(1Z-propenyl)-benzene (27); three benzopyranoids 3,4-dihydro-4,4,5,8-tetramethylcoumarin (18), 3,4-dihydro-4,4,7,8-tetramethylcoumarin-6-ol (19), 1,3,4,6,7,8-hexahydro-4,6,6,7,8,8-hexamethyl-cyclopenta[g]-2-benzopyran (22); one sesquiterpene methyl-3,7,11-trimethyl-2E,6E,10-dodecatrienoate (21); three esters of fatty acids methyl 14-methyl-pentadecanoate (23), ethyl hexadecanoate (24), ethyl 9Z-octadecenoate (25) and one monoterpene 3,7-dimethyl-1-octen-7-ol (26) were identified. Except 6, 8, 24 and 25 all these compounds were identified for the first time from the pericarp and fifteen of these, 1-3, 7, 9, 10, 17-23, 26, 27, are hitherto unreported previously from any part of the tree. Although this tree is a rich source of various natural products, it is the first report of identification of mono- and sesquiterpenes 26 and 21 and a potent antioxidant, 17. 相似文献
69.
Paul A. Lapchak Paul D. Boitano Pramod V. Butte David J. Fisher Thilo H?lscher Eric J. Ley Miriam Nu?o Arne H. Voie Padmesh S. Rajput 《PloS one》2015,10(6)
Background and Purpose
Transcranial near-infrared laser therapy (TLT) is a promising and novel method to promote neuroprotection and clinical improvement in both acute and chronic neurodegenerative diseases such as acute ischemic stroke (AIS), traumatic brain injury (TBI), and Alzheimer’s disease (AD) patients based upon efficacy in translational animal models. However, there is limited information in the peer-reviewed literature pertaining to transcranial near-infrared laser transmission (NILT) profiles in various species. Thus, in the present study we systematically evaluated NILT characteristics through the skull of 4 different species: mouse, rat, rabbit and human.Results
Using dehydrated skulls from 3 animal species, using a wavelength of 800nm and a surface power density of 700 mW/cm2, NILT decreased from 40.10% (mouse) to 21.24% (rat) to 11.36% (rabbit) as skull thickness measured at bregma increased from 0.44 mm in mouse to 0.83 mm in rat and then 2.11 mm in rabbit. NILT also significantly increased (p<0.05) when animal skulls were hydrated (i.e. compared to dehydrated); but there was no measurable change in thickness due to hydration.In human calvaria, where mean thickness ranged from 7.19 mm at bregma to 5.91 mm in the parietal skull, only 4.18% and 4.24% of applied near-infrared light was transmitted through the skull. There was a slight (9.2-13.4%), but insignificant effect of hydration state on NILT transmission of human skulls, but there was a significant positive correlation between NILT and thickness at bregma and parietal skull, in both hydrated and dehydrated states.Conclusion
This is the first systematic study to demonstrate differential NILT through the skulls of 4 different species; with an inverse relationship between NILT and skull thickness. With animal skulls, transmission profiles are dependent upon the hydration state of the skull, with significantly greater penetration through hydrated skulls compared to dehydrated skulls. Using human skulls, we demonstrate a significant correlation between thickness and penetration, but there was no correlation with skull density. The results suggest that TLT should be optimized in animals using novel approaches incorporating human skull characteristics, because of significant variance of NILT profiles directly related to skull thickness. 相似文献70.
Liu XQ Rajput A Geng L Ongchin M Chaudhuri A Wang J 《The Journal of biological chemistry》2011,286(18):16082-16090
Microsatellite instability (MSI), which occurs in 15% of colorectal cancer, has been shown to have a lower incidence of metastasis and better patient survival rates compared with microsatellite stable colorectal cancer. However, a mechanistic understanding of the basis for this difference is very limited. Here, we show that restoration of TGFβ signaling by re-expression of TGFβ receptor II in MSI colon cancer cells increased PI3K/AKT activation, conferred resistance to growth factor deprivation stress-induced apoptosis, and promoted cell motility in vitro. Treatment with a potent PI3K inhibitor (LY294002) blocked the prosurvival and promotility effects of TGFβ, indicating that TGFβ-mediated promotion of cell survival and motility is dependent upon activation of the PI3K/AKT pathway. Analysis of apoptotic effectors that are affected by TGFβ signaling indicated that Bim is an effector of TGFβ-mediated survival. In addition, TGFβ-induced down-regulation of E-cadherin contributed to the prosurvival effect of TGFβ, and restoration of TGFβ signaling in MSI colon cancer cells increased liver metastasis in an orthotopic model in vivo. Taken together, our results demonstrate that restoration of TGFβ signaling promotes cell survival, motility, and metastatic progression in MSI colon cancer cells and indicate that TGFβ receptor II mutations contribute to the favorable outcomes in colon cancer patients with MSI. 相似文献