全文获取类型
收费全文 | 451篇 |
免费 | 26篇 |
出版年
2023年 | 10篇 |
2022年 | 8篇 |
2021年 | 22篇 |
2020年 | 12篇 |
2019年 | 6篇 |
2018年 | 5篇 |
2017年 | 12篇 |
2016年 | 20篇 |
2015年 | 29篇 |
2014年 | 23篇 |
2013年 | 44篇 |
2012年 | 35篇 |
2011年 | 46篇 |
2010年 | 31篇 |
2009年 | 20篇 |
2008年 | 16篇 |
2007年 | 24篇 |
2006年 | 11篇 |
2005年 | 12篇 |
2004年 | 14篇 |
2003年 | 15篇 |
2002年 | 11篇 |
2001年 | 4篇 |
2000年 | 3篇 |
1999年 | 3篇 |
1998年 | 3篇 |
1997年 | 3篇 |
1996年 | 3篇 |
1995年 | 4篇 |
1994年 | 4篇 |
1993年 | 1篇 |
1992年 | 1篇 |
1991年 | 5篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1986年 | 1篇 |
1980年 | 1篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1974年 | 1篇 |
1973年 | 1篇 |
1972年 | 3篇 |
1968年 | 4篇 |
1965年 | 1篇 |
排序方式: 共有477条查询结果,搜索用时 171 毫秒
431.
Soumit K. Behera Ashish K. Mishra Nayan Sahu Amrit Kumar Niraj Singh Anoop Kumar Omesh Bajpai L. B. Chaudhary Prem B. Khare Rakesh Tuli 《Biodiversity and Conservation》2012,21(5):1159-1176
The data on microclimate were collected between 2010 and 2011 in five forest communities (dry miscellaneous, sal mixed, lowland
miscellaneous, teak and savannah) in a tropical moist deciduous forest in Katerniaghat Wildlife Sanctuary, Uttar Pradesh,
India to compare how vegetation structure affects microclimate. Diurnal variations in microclimatic variables [photosynthetically
active radiation (PAR) at forest understory level, air temperature, soil surface temperature, ambient CO2, air absolute humidity] were measured with LI-COR 840, LI-COR 191, LI-COR 190 SZ, LI-1400-101 and LI-1400-103 (LI-COR; Lincoln,
NE, USA) at centre of three 0.5 ha plots in each forest community. The diurnal trend in microclimatic parameters showed wide
variations among communities. PAR at forest floor ranged from 0.0024 to 1289.9 (μmol m−2s−1) in post-monsoon season and 0.0012 to 1877.3 (μmol m−2s−1) in mid-winter season. Among the five communities, the highest PAR value was observed in savannah and lowest in sal mixed
forest. All the forest communities received maximum PAR at forest floor between 1000 and 1200 h. The ambient air temperature
ranged from 19.15 to 26.69°C in post-monsoon season and 11.31 to 23.03°C in mid-winter season. Soil temperature ranged from
13.54 to 36.88°C in post-monsoon season and 6.39 to 29.17°C in mid-winter season. Ambient CO2 ranged from 372.16 to 899.14 μmol mol−1 in post-monsoon season and 396.65 to 699.65 μmol mol−1 in mid-winter season. In savannah ecosystem, diurnal trend of ambient CO2 was totally different from rest four communities. According to Canonical correspondence analysis, PAR and ambient CO2 are most important in establishment of forest community, among microclimatic variables. 相似文献
432.
433.
Geetu Singh Prasoon Gupta Preeti Rawat Anju Puri Gitika Bhatia Rakesh Maurya 《Phytomedicine》2007,14(12):792-798
Ethanol extract of Coccinia grandis (L.) Voigt showed significant triglyceride (TG) and cholesterol-lowering effects in dyslipidemic hamster model. Ethanolic extract was fractionated into chloroform, n-butanol and water-soluble fractions and were evaluated. Activity was proved to be concentrated in chloroform-soluble fraction. Chloroform-soluble fraction containing active component was subjected to repeated column chromatography, furnished a polyprenol characterized as C60-polyprenol (1) isolated for the first time from this plant. It significantly decreased serum TG by 42%, total cholesterol (TC) 25% and glycerol (Gly) 12%, accompanied HDL-C/TC ratio 26% in high-fat diet (HFD)-fed dyslipidemic hamsters at the dose of 50 mg/kg body weight. Results are comparable to standard drug fenofibrate at the dose of 108 mg/kg. Based on these investigations, it was concluded that the compound polyprenol (1) isolated from leaves of C. grandis possess marked antidyslipidemic activity. 相似文献
434.
Gauri Garg Dhingra Anjali Saxena Aeshna Nigam Princy Hira Nirjara Singhvi Shailly Anand Jasvinder Kaur Jaspreet Kaur Ankita Dua Vivek Negi Vipin Gupta Utkarsh Sood Roshan Kumar Sukanya Lal Helianthous Verma Mansi Verma Priya Singh Charu Dogra Rawat Charu Tripathi Chandni Talwar Shekhar Nagar Nitish Kumar Mahato Om Prakash Mona Singh R. C. Kuhad Yogendra Singh Banwari Lal Sunil Pabbi Namita Singh V. C. Kalia Rup Lal 《Indian journal of microbiology》2021,61(2):111
435.
Divya Rawat Saurabh Kumar Chhonker Rayees Ahmad Naik Raj Kumar Koiri 《Journal of biochemical and molecular toxicology》2021,35(1)
Hepatocellular carcinoma (HCC) is the fifth most commonly diagnosed cancer worldwide and is associated with poor prognosis. The current study aimed to assess the therapeutic efficacy of resveratrol when administered alone and in combination with nicotinamide against alcohol‐aflatoxin B1‐induced HCC. Results reveal that during the development and progression of cancer, there was a decline in the level of antioxidant enzymes catalase, glutathione peroxidase, glutathione reductase (GR), antioxidant glutathione, and glutathione S‐transferase, which is an enzyme of detoxification pathways. Treatment of resveratrol restored the level of catalase and glutathione peroxidase toward normal in alcohol‐aflatoxin B1‐induced HCC; however, nicotinamide worked in concert with resveratrol only in upregulating the activity of glutathione reductase, glutathione level, and glutathione S‐transferase. SIRT1 agonist resveratrol was observed to modulate the activity of antioxidant enzymes by negatively regulating the expression of nuclear factor‐κB (NF‐κB) in alcohol‐aflatoxin B1‐induced HCC, thereby suggesting a cross‐talk between antioxidant enzymes SIRT1 and NF‐κB during the development and progression of HCC and its therapeutics by resveratrol and nicotinamide. 相似文献
436.
Arunagiri Anoop Srivastav Ranganathan Bhagwan Das Dhaked Narendra Nath Jha Supriya Pratihar Saikat Ghosh Shruti Sahay Santosh Kumar Subhadeep Das Mamata Kombrabail Kumud Agarwal Reeba S. Jacob Praful Singru Prasenjit Bhaumik Ranjith Padinhateeri Ashutosh Kumar Samir K. Maji 《The Journal of biological chemistry》2014,289(24):16884-16903
The storage of protein/peptide hormones within subcellular compartments and subsequent release are crucial for their native function, and hence these processes are intricately regulated in mammalian systems. Several peptide hormones were recently suggested to be stored as amyloids within endocrine secretory granules. This leads to an apparent paradox where storage requires formation of aggregates, and their function requires a supply of non-aggregated peptides on demand. The precise mechanism behind amyloid formation by these hormones and their subsequent release remain an open question. To address this, we examined aggregation and fibril reversibility of a cyclic peptide hormone somatostatin (SST)-14 using various techniques. After proving that SST gets stored as amyloid in vivo, we investigated the role of native structure in modulating its conformational dynamics and self-association by disrupting the disulfide bridge (Cys3–Cys14) in SST. Using two-dimensional NMR, we resolved the initial structure of somatostatin-14 leading to aggregation and further probed its conformational dynamics in silico. The perturbation in native structure (S-S cleavage) led to a significant increase in conformational flexibility and resulted in rapid amyloid formation. The fibrils formed by disulfide-reduced noncyclic SST possess greater resistance to denaturing conditions with decreased monomer releasing potency. MD simulations reveal marked differences in the intermolecular interactions in SST and noncyclic SST providing plausible explanation for differential aggregation and fibril reversibility observed experimentally in these structural variants. Our findings thus emphasize that subtle changes in the native structure of peptide hormone(s) could alter its conformational dynamics and amyloid formation, which might have significant implications on their reversible storage and secretion. 相似文献
437.
Effective and specific in planta RNAi in cyst nematodes: expression interference of four parasitism genes reduces parasitic success 总被引:3,自引:0,他引:3
下载免费PDF全文
![点击此处可从《Journal of experimental botany》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Sindhu Anoop S.; Maier Tom R.; Mitchum Melissa G.; Hussey Richard S.; Davis Eric L.; Baum Thomas J. 《Journal of experimental botany》2009,60(1):315-324
Cyst nematodes are highly evolved sedentary plant endoparasitesthat use parasitism proteins injected through the stylet intohost tissues to successfully parasitize plants. These secretoryproteins likely are essential for parasitism as they are involvedin a variety of parasitic events leading to the establishmentof specialized feeding cells required by the nematode to obtainnourishment. With the advent of RNA interference (RNAi) technologyand the demonstration of host-induced gene silencing in parasites,a new strategy to control pests and pathogens has become available,particularly in root-knot nematodes. Plant host-induced silencingof cyst nematode genes so far has had only limited success butsimilarly should disrupt the parasitic cycle and render thehost plant resistant. Additional in planta RNAi data for cystnematodes are being provided by targeting four parasitism genesthrough host-induced RNAi gene silencing in transgenic Arabidopsisthaliana, which is a host for the sugar beet cyst nematode Heteroderaschachtii. Here it is reported that mRNA abundances of targetednematode genes were specifically reduced in nematodes feedingon plants expressing corresponding RNAi constructs. Furthermore,this host-induced RNAi of all four nematode parasitism genesled to a reduction in the number of mature nematode females.Although no complete resistance was observed, the reductionof developing females ranged from 23% to 64% in different RNAilines. These observations demonstrate the relevance of the targetedparasitism genes during the nematode life cycle and, potentiallymore importantly, suggest that a viable level of resistancein crop plants may be accomplished in the future using thistechnology against cyst nematodes. Key words: beet cyst nematode (BCN), soybean cyst nematode (SCN), host induced, in planta RNAi, resistance, RNAi, transgenic
Received 19 August 2008; Revised 25 October 2008 Accepted 27 October 2008 相似文献
438.
Our previous studies show that the depletion of cholesterol or sphingolipids (raft-associated lipids) from receptor-bearing
adherent cell lines blocks HIV-1 entry and HIV-1 Env-mediated membrane fusion. Here we have evaluated the mechanism(s) by
which these lipids contribute to the HIV-1 Env-mediated membrane fusion. We report the following: (1) GSL depletion from a
suspension T lymphocyte cell line (Sup-T1) reduced subsequent fusion with HIV-1IIIB-expressing cells by 70%. (2) Cholesterol
depletion from NIH3T3 cells bearing HIV-1 receptors (NIH3T3CD4R5/NIH3T3CD4X4) did not impair subsequent fusion with HeLa cells
expressing the corresponding HIV-1 Envs. In contrast GSL depletion from these targets reduced fusion by 50% suggesting that
GSL facilitate fusion in different ways. (3) GSL-deficient GM95 cells bearing high receptors fused with HIV-1 Env-expressing
cells at 37°C with kinetics similar to that of GSL + NIH3T3 targets. Based on these observations, we propose that the plasma
membrane cholesterol is required to maintain the integrity of receptor pools whereas GSLs are involved in stabilizing the
coupling of inter-receptor pools. 相似文献
439.
ATP-dependent Clp protease (ClpP) is a core unit of a major bacterial protease complex employing as a new attractive drug target for that isolates, which are resistant to antibiotics. Mycobacterium tuberculosis, a gram-positive bacterium, is one of the major causes of hospital acquired infections. ClpP in Mycobacterium tuberculosis is usually tightly regulated and strictly requires a member of the family of Clp-ATPase and often further accessory proteins for proteolytic activation. Inhibition of ClpP eliminates these safeguards and start proteolytic degradation. Such uncontrolled proteolysis leads to inhibition of bacterial cell division and eventually cell death. In order to inhibit Clp protease, at first three dimensional structure model of ClpP in Mycobacterium tuberculosis was determined by comparative homology modeling program MODELLER based on crystal structure of the proteolytic component of the caseinolytic Clp protease (ClpP) from E. coli as a template protein and has 55%sequence identity with ClpP protein. The computed model's energy was minimized and validated using PROCHECK to obtain a stable model structure and is submitted in Protein Model Database (PMDB-ID: PM0075741). Stable model was further used for virtual screening against marine derived bioactive compound database through molecular docking studies using AutoDock 3.05. The docked complexes were validated and enumerated based on the AutoDock Scoring function to pick out the best marine inhibitors based on docked Energy. Thus from the entire 186 Marine compounds which were Docked, we got best 5 of them with optimal docked Energy (Ara-A: -14.31 kcal/mol, Dysinosin C: - 14.90kcal/mol, Nagelamide A: -20.49 kcal/mol, Strobilin: -8.02 kcal/mol, Manoalide: -8.81 kcal/mol). Further the five best-docked complexes were analyzed through Python Molecular Viewer software for their interaction studies. Thus from the Complex scoring and binding ability its deciphered that these Marine compounds could be promising inhibitors for ClpP as Drug target yet pharmacological studies have to confirm it. 相似文献
440.