全文获取类型
收费全文 | 1320篇 |
免费 | 75篇 |
国内免费 | 1篇 |
出版年
2022年 | 15篇 |
2021年 | 34篇 |
2020年 | 11篇 |
2019年 | 16篇 |
2018年 | 22篇 |
2017年 | 22篇 |
2016年 | 33篇 |
2015年 | 45篇 |
2014年 | 47篇 |
2013年 | 78篇 |
2012年 | 88篇 |
2011年 | 96篇 |
2010年 | 54篇 |
2009年 | 50篇 |
2008年 | 70篇 |
2007年 | 52篇 |
2006年 | 45篇 |
2005年 | 63篇 |
2004年 | 68篇 |
2003年 | 34篇 |
2002年 | 38篇 |
2001年 | 26篇 |
2000年 | 19篇 |
1999年 | 13篇 |
1998年 | 17篇 |
1997年 | 12篇 |
1996年 | 12篇 |
1992年 | 11篇 |
1991年 | 7篇 |
1990年 | 16篇 |
1989年 | 11篇 |
1988年 | 19篇 |
1987年 | 13篇 |
1986年 | 9篇 |
1985年 | 16篇 |
1984年 | 12篇 |
1983年 | 15篇 |
1982年 | 8篇 |
1981年 | 17篇 |
1980年 | 18篇 |
1979年 | 7篇 |
1978年 | 16篇 |
1977年 | 10篇 |
1976年 | 13篇 |
1975年 | 12篇 |
1974年 | 9篇 |
1973年 | 10篇 |
1972年 | 7篇 |
1971年 | 11篇 |
1970年 | 9篇 |
排序方式: 共有1396条查询结果,搜索用时 265 毫秒
51.
Govindan Nadar Rajivgandhi Chelliah Chenthis Kanisha Govindan Ramachandran Natesan Manoharan Ramzi A. Mothana Nasir A. Siddiqui Adnan J. Al-Rehaily Riaz Ullah Omer M. Almarfadi 《Saudi Journal of Biological Sciences》2021,28(3):1763-1769
In this study, the phytochemical, phenolic, flavonoid and bioactive compounds were successfully screened from crude extract of Sargassum wightii by LC-MS analysis after NIST interpretation. Bacterial growth inhibition study result was shown with 24 mm zone inhibition at 200 µg/mL concentration against P. aeruginosa. The increased phenolic content was much closed to gallic acid and the range was observed at 250 μg/mL concentration. In addition, flavonoid contents of the algae extract was indicated more significant with rutin at 200 μg/mL. In result, both the phenolic and flavonoid contents of the extract were more correlated with gallic acid and rutin. Further, the total anti-oxidant and DPPH radical scavenging activities were shown increased activity at 200 μg/mL concentrations. Furthermore, the excellent anti-bacterial alteration result was observed at 200 μg/mL concentration by minimum inhibition concentration. Therefore, the result was revealed that the marine algae Sargassum wightii has excellent phytochemical and anti-oxidant activities, and it has improved anti-bacterial activity against P. aeruginosa. 相似文献
52.
The interaction of naringenin (Nar) and its neohesperidoside, naringin (Narn), with calf thymus deoxyribonucleic acid (ctDNA) in the absence and the presence of β-cyclodextrin (β-CD) was investigated. The interaction of Nar and Narn with β-CD/ctDNA was analyzed by using absorption, fluorescence, and molecular modeling techniques. Docking studies showed the existence of hydrogen bonding, electrostatic and phobic interaction of Nar and Narn with β-CD/DNA. 1:2 stoichiometric inclusion complexes were observed for Nar and Narn with β-CD. With the addition of ctDNA, Nar and Narn resulted into the fluorescence quenching phenomenon in the aqueous solution and β-CD solution. The binding constant K b and the number of binding sites were found to be different for Nar and Narn bindings with DNA in aqueous and β-CD solution. The difference is attributed to the structural difference between Nar and Narn with neohesperidoside moiety present in Narn. 相似文献
53.
54.
Qiang Wei Stefano Costanzi Ramachandran Balasubramanian Zhan-Guo Gao Kenneth A. Jacobson 《Purinergic signalling》2013,9(2):271-280
The role of the A2B adenosine receptor (AR) in prostate cell death and growth was studied. The A2B AR gene expression quantified by real-time quantitative RT-PCR and Western blot analysis was the highest among four AR subtypes (A1, A2A, A2B, and A3) in all three commonly used prostate cancer cell lines, PC-3, DU145, and LNCaP. We explored the function of the A2B AR using PC-3 cells as a model. The A2B AR was visualized in PC-3 cells by laser confocal microscopy. The nonselective A2B AR agonist NECA and the selective A2B AR agonist BAY60-6583, but not the A2A AR agonist CGS21680, concentration-dependently induced adenosine 3′,5′-cyclic monophosphate (cyclic AMP) accumulation. NECA diminished lactate dehydrogenase (LDH) release, TNF-α-induced increase of caspase-3 activity, and cycloheximide (CHX)-induced morphological changes typical of apoptosis in PC-3 cells, which were blocked by a selective A2B AR antagonist PSB603. NECA-induced proliferation of PC-3 cells was diminished by siRNA specific for the A2B AR. The selective A2B AR antagonist PSB603 was shown to inhibit cell growth in all three cell lines. Thus, A2B AR blockade inhibits growth of prostate cancer cells, suggesting selective A2B AR antagonists as potential novel therapeutics. 相似文献
55.
André Mischo Oliver Ohlenschläger Ramadurai Ramachandran Matthias Görlach 《Biomolecular NMR assignments》2013,7(1):47-49
The resonance assignment of an amino-terminal pyroglutamic acid containing peptide derived from the E6 protein of human papillomavirus (HPV) type 51 in complex with PDZ domain 2 of hDlg/SAP-97 is reported. The assignments include 1H, 13C and 15N resonances for the protein and peptide in the complex and all of the peptide’s pyroglutamic acid nuclei. 相似文献
56.
Kidney transplantation (KT) is only viable renal replacement option for most patients in India. Most patients do not have health insurance and meet treatment expenditure from their own resources. We prospectively evaluated the expenses associated with KT and its impact on the socioeconomic status of families in a public hospital. All direct and indirect expenses incurred by the patients from the time of diagnosis of chronic kidney disease to KT were recorded. Direct expenses included physician fees, cost of drugs and disposables, dialysis, and expenses on investigations and hospitalization. Indirect expenses included travel, food, stay, and loss of income suffered by the family. Educational dropout and financial loss were also recorded. There were 43 males and 7 females between the ages of 12 and 57 years. Direct expenses ranged from US$ 2,151–23,792 and accounted for two-thirds of the total expenses. Pre-referral hospitalization, dialysis and medication accounted for majority of direct expense. Indirect expenses ranged from US$ 226–15,283. Travel expenses and loss of income accounted for most of indirect expense. About 54%, 8%, and 10% of families suffered from severe, moderate, and some financial crisis respectively. A total of 38 families had job losses, and 1 patient and 12 caregivers dropped out of studies. To conclude, KT is associated with catastrophic out-of-pocket expenditure and pushes a majority of the patients who come for treatment to public hospitals into severe financial crisis. Educational dropout and loss of jobs are other major concerns. Systematic efforts are required to address these issues. 相似文献
57.
Brian A. Chow Seth W. Donahue Michael R. Vaughan Brendan McConkey Mathilakath M. Vijayan 《PloS one》2013,8(6)
Hibernation is an adaptation to conserve energy in the face of extreme environmental conditions and low food availability that has risen in several animal phyla. This phenomenon is characterized by reduced metabolic rate (∼25% of the active basal metabolic rate in hibernating bears) and energy demand, while other physiological adjustments are far from clear. The profiling of the serum proteome of the American black bear (Ursus americanus) may reveal specific proteins that are differentially modulated by hibernation, and provide insight into the remarkable physiological adaptations that characterize ursid hibernation. In this study, we used differential gel electrophoresis (DIGE) analysis, liquid chromatography coupled to tandem mass spectrometry, and subsequent MASCOT analysis of the mass spectra to identify candidate proteins that are differentially expressed during hibernation in captive black bears. Seventy serum proteins were identified as changing by ±1.5 fold or more, out of which 34 proteins increased expression during hibernation. The majority of identified proteins are involved in immune system processes. These included α2-macroglobulin, complement components C1s and C4, immunoglobulin μ and J chains, clusterin, haptoglobin, C4b binding protein, kininogen 1, α2-HS-glycoprotein, and apoplipoproteins A-I and A-IV. Differential expression of a subset of these proteins identified by proteomic analysis was also confirmed by immunodetection. We propose that the observed serum protein changes contribute to the maintenance of the hibernation phenotype and health, including increased capacities for bone maintenance and wound healing during hibernation in bears. 相似文献
58.
Ajay Kumar D.M. Pandey Thomson Abraham Jacob Mathew Padma Ramachandran 《Archives Of Phytopathology And Plant Protection》2013,46(6):710-720
Tapping panel dryness (TPD) syndrome affecting rubber tree (Hevea brasiliensis) is known to reduce natural latex production. Its aetiology remains ambiguous despite long years of research. A low molecular weight RNA similar to viroid RNA was isolated from TPD-affected samples of rubber trees. In the present study, a modified return-polyacrylamide gel electrophoresis procedure was standardised. The viroid-like low molecular weight (LMW) RNA was found associated with leaf, bark and root tissues and rubber seedlings. The technique was employed to detect LMW RNA in different clones of rubber planted in different locations and in bud-grafted plants. The LMW RNA isolated from TPD-affected trees was found infectious on seedlings of tomato cv Pusa Ruby. The LMW RNA was reisolated from symptomatic tomato leaves but not from control plants. This is for the first time that a biotic agent, a viroid RNA, is found consistently associated with the syndrome. The technology developed can be useful to demonstrate the onset of TPD in untapped trees in the absence of other methods such as nucleic acid hybridisation. 相似文献
59.
A.K. Vijayan L. Sithara Joseph Thomas J. Thomas R.S. Misra K.A. Saju 《Archives Of Phytopathology And Plant Protection》2013,46(18):2270-2277
Incidence of root rot and foliar yellowing, rhizome rot, panicle wilt and stem rot diseases of small cardamom (Elettaria cardamomum Maton) are caused by Fusarium oxysporum Schlecht., and were surveyed in the high ranges of Idukki district, Kerala during 2010–2011. The diseases were noticed in different areas to varying degrees. Root rot was found to be most severe, followed by pseudostem rot, rhizome rot and panicle wilt. The Fusarium infections were prevalent throughout the year (January–December) and varied from 1.5 to 10.6%. Even though the pathogen was isolated from different plant parts, during pathogenicity studies, all the isolates could cross-infect other plant parts too. Twenty different isolates of F. oxysporum were obtained from diseased samples, and five morphologically distinct isolates were analysed with Randomly Amplified Polymorphic DNA (RAPD) markers to study the genetic variability, if any, among them. PCR amplification of total genomic DNA with random oligonucleotide primers generated unique banding patterns, depending upon primers and isolates. Nine oligunucleotide primers were selected for the RAPD assays, which resulted in 221 bands for the five isolates of F. oxysporum. The number of bands obtained was entered into an NTSYS, and the results showed moderate genetic variability among F. oxysporum isolates causing root rot, rhizome rot, panicle wilt and pseudostem rot, collected from different locations. The dendrogram of different isolates into groups resulted in one major cluster at 0.61 similarity index comprising of four isolates (CRT 3, CRR 3, CPW 2 and CSR 1) and one isolate (CRT 5) formed in a separate cluster. Among the five isolates of F. oxysporum, CRT 5 was entirely different from the other four isolates. The isolates also differ according to the geographical area, as revealed from the genetic variability observed in different root rot isolates (CRT 3 and CRT 5). It is inferred that despite moderate variability, F. oxysporum, infecting small cardamom in Idukki district of Kerala, consists of a single clonal lineage. 相似文献
60.
G. Smilin Bell Aseervatham Thilagar Sivasudha Mohan Suganya Angappan Rameshkumar Ramachandran Jeyadevi 《Neurochemical research》2013,38(8):1715-1725
Epilepsy prevails to be a neurological disorder in anticipation of safer drugs with enhanced anticonvulsant efficacy as presently available drugs fails to offer adequate control of epileptic seizures in about one-third of patients. The objective of this study was to evaluate the effect of Trichosanthes tricuspidata methanolic extract (TTME) against epilepsy mediated oxidative stress in pilocarpine induced mice. Intraperitonial administration of pilocarpine (85 mg/kg) induced seizure in mice was assessed by behavior observations, which is significantly (p < 0.05) reduced by TTME (100 and 200 mg/kg; i.p) in a dose dependant manner, similar to diazepam. Seizure was accompanied by significant increase in lipid peroxidation and the hippocampal nitrite content in pilocarpine group when compared with control. Moreover, the antioxidant enzymes superoxide dismutase, catalase and glutathione levels were decreased in pilocarpine administered groups. TTME administration attenuated oxidative damage as evident by decreased lipid oxidative damage and nitrite–nitrate content and restored the level of enzymatic antioxidant defenses in hippocampus. Involvement of free radicals during epilepsy is further confirmed by histopathological analysis which showed the loss of neuronal cells in hippocampus CA1 and CA3 pyramidal region. Our findings strongly support the hypothesis that TTME has anticonvulsant activity accompanied with the strong antioxidant potential plays a crucial role in reducing the oxidative stress produced by seizure. 相似文献