全文获取类型
收费全文 | 993篇 |
免费 | 49篇 |
出版年
2023年 | 13篇 |
2022年 | 13篇 |
2021年 | 31篇 |
2020年 | 17篇 |
2019年 | 25篇 |
2018年 | 28篇 |
2017年 | 26篇 |
2016年 | 33篇 |
2015年 | 51篇 |
2014年 | 48篇 |
2013年 | 72篇 |
2012年 | 75篇 |
2011年 | 72篇 |
2010年 | 41篇 |
2009年 | 35篇 |
2008年 | 49篇 |
2007年 | 44篇 |
2006年 | 35篇 |
2005年 | 35篇 |
2004年 | 30篇 |
2003年 | 25篇 |
2002年 | 18篇 |
2001年 | 20篇 |
2000年 | 15篇 |
1999年 | 18篇 |
1998年 | 4篇 |
1997年 | 3篇 |
1996年 | 4篇 |
1995年 | 6篇 |
1994年 | 6篇 |
1993年 | 6篇 |
1992年 | 16篇 |
1991年 | 12篇 |
1990年 | 11篇 |
1989年 | 17篇 |
1988年 | 6篇 |
1987年 | 10篇 |
1986年 | 4篇 |
1985年 | 10篇 |
1984年 | 6篇 |
1982年 | 3篇 |
1981年 | 6篇 |
1979年 | 7篇 |
1978年 | 3篇 |
1977年 | 7篇 |
1975年 | 5篇 |
1972年 | 2篇 |
1971年 | 2篇 |
1970年 | 2篇 |
1966年 | 3篇 |
排序方式: 共有1042条查询结果,搜索用时 484 毫秒
921.
IL-12 and IL-18 are immunomodulatory cytokines that play important roles in host immune response against cancers. Variation in DNA sequence in gene promoter may lead to altered IL-18 production and/or activity, and hence can modulate an individual's susceptibility to BC. To test this hypothesis, we investigated the relationship of IL-18 gene promoter −137 G/C and −607C/A polymorphisms and IL12 (− 16974) A/C with the risk of BC in North Indian population. Polymorphisms in IL-18 and IL-12 genes were analyzed in 200 BC patients and 200 age, ethnicity and sex-matched controls, using restriction fragment length polymorphism-polymerase chain reaction (PCR-RFLP) and amplification refractory mutation specific-polymerase chain reaction (ARMS) method. The concentrations of IL-18 in serum were determined by ELISA. Significant association was observed with IL18 (− 137) G/C heterozygous genotype (GC) with 1.96 folds risk of BC as well at C allele carrier and variant C allele having 2 fold and 1.6 fold risk for BC respectively. IL18 (− 607) C/A, heterozygous CA genotype also showed a high risk (OR = 1.59) for BC. While IL12 (− 16974) A/C heterozygote genotype and C allele carrier demonstrated reduced risk of BC. Hetero genotype of IL18 (− 137) G/C was associated with risk of recurrence (HR = 2.35) in superficial BC patients receiving BCG treatment thus showing least survival. The distributions of IL-18 gene haplotypes were not significantly different between patients and controls. Serum IL-18 levels were significantly higher in BC patients than in the healthy subjects (p = 0.025). Serum IL-18 levels was also significantly associated with IL18 (− 137) G/C in heterozygous genotype (GC) (p = 0.048). Our results suggest that IL-18 gene polymorphism contributes to bladder cancer risk whereas IL-12 is protective. A relation between IL18 (− 137) G/C in heterozygous genotype with elevated IL-18 serum level and bladder cancer risk has been registered in the present study. 相似文献
922.
923.
S. Pradeep P. Faseela M. K. Sarath Josh S. Balachandran R. Sudha Devi Sailas Benjamin 《Biodegradation》2013,24(2):257-267
This unique study describes how Aspergillus japonicus, Penicillium brocae and Purpureocillium lilacinum, three novel isolates of our laboratory from heavily plastics-contaminated soil completely utilized the plasticizer di(2-ethylhexyl)phthalate (DEHP) bound to PVC blood storage bags (BB) in simple basal salt medium (BSM) by static submerged growth (28 °C). Initial quantification as well as percentage utilization of DEHP blended to BB were estimated periodically by extracting it into n-hexane. A two-stage cultivation strategy was employed for the complete mycoremediation of DEHP from BB in situ. During the first growth stage, about two-third parts of total (33.5 % w/w) DEHP bound to BB were utilized in two weeks, accompanied by increased fungal biomass (~0.15–0.32 g per g BB) and sharp declining (to ~3) of initial pH (7.2). At this stagnant growth state (low pH), spent medium was replaced by fresh BSM (pH, 7.2), and thus in the second stage the remaining DEHP (one-third) in BB was utilized completely. The ditches and furrows seen from the topology of the BB as seen by the 3D AFM image further confirmed the bioremediation of DEHP physically bound to BB in situ. Of the three mycelial fungi employed, P. lilacinum independently showed highest efficiency for the complete utilization of DEHP bound to BB, whose activity was comparable to that of the consortium comprising all the three fungi described herein. To sum up, the two-stage cultivation strategy demonstrated in this study shows that a batch process would efficiently remediate the phthalic acid esters blended in plastics on a large scale, and thus it offers potentials for the management of plastics wastes. 相似文献
924.
K. M. Ramkumar C. Manjula B. Elango K. Krishnamurthi S. Saravana Devi P. Rajaguru 《Cell proliferation》2013,46(3):263-271
Objectives
Gymnema montanum Hook, an Indian Ayurvedic medicinal plant, is used traditionally to treat a variety of ailments. Here, we report anti‐cancer effects and molecular mechanisms of ethanolic extract of G. montanum (GLEt) on human leukaemia HL‐60 cells, compared to peripheral blood mononuclear cells.Materials and methods
HL‐60 cells were treated with different concentrations of GLEt (10–50 μg/ml) and cytotoxicity was assessed by MTT assay. Levels of lipid peroxidation, antioxidants, mitochondrial membrane potential and caspase‐3 were measured. Further, apoptosis was studied using annexin‐V staining and the cell cycle was analyzed by flow cytometry.Results
GLEt had a potent cytotoxic effect on HL‐60 cells (IC50‐20 μg/ml), yet was not toxic to normal peripheral blood mononuclear cells. Exposure of HL‐60 cells to GLEt led to elevated levels of malonaldehyde formation, but to reduced glutathione, superoxide dismutase, catalase and glutathione peroxidase activities (P < 0.05). Induction of apoptosis was confirmed by observing annexin‐V positive cells, associated with loss of mitochondrial membrane potential. Cell cycle arrest at G0/G1 was observed in GLEt‐treated HL‐60 cells, indicating its potential at inducing their apoptosis.Conclusions
Findings of the present study suggest that G. montanum induced apoptosis in the human leukaemic cancer cells, mediated by collapse of mitochondrial membrane potential, generation of reactive oxygen species and depletion of intracellular antioxidant potential.925.
Praveen Kumar Jaiswal Vibha Singh Rama Devi Mittal 《Indian journal of human genetics》2013,19(3):293-300
BACKGROUND AND AIM:
p73, a novel P53 homolog and plays an important role in modulating cell cycle control, apoptosis and cell growth while P21, functions to negatively control the cell cycle. P53 up regulates p21 expression in response to deoxyribonucleic acid damage leading to cell cycle arrest at G1 checkpoint. In the present study, we are targeting p21 codon 31 and p73 gene variants of G4C14-to-A4T14 (Exon 2) polymorphism for bladder cancer (BC) risk in North Indians.MATERIALS AND METHODS:
The above gene variants of P21 and P73 were assessed in the case-control study comprising of 200 BC cases and 200 healthy controls of the same age, gender and similar ethnicity. Genotyping was performed by polymerase chain reaction (PCR) restriction fragment length polymorphism method and PCR-based confronting two-pair primers (PCR with CTPP).RESULTS:
The variant genotype of p73Exon 2 polymorphism showed significant risk for BC (p = 0.014). While combining with heterozygous genotype, variant genotype of p73Exon2 showed a significant association with BC risk (p = 0.010). While in case of p21 codon31 showed no significant association for BC risk at genotypic level. Significant association between p73Exon2 polymorphism and smoking was observed for BC risk. Furthermore, gene combination analysis revealed that AT/AT-Ser/Ser is associated with risk for BC. Variant genotype of P73Exon2 was associated with reduced risk of recurrence (p = 0.039) in superficial BC patients receiving Bacillus Calmette-Guerin treatment thus showing least survival (log rank = 0.029).CONCLUSION:
Our study provided evidence that the p73 G4C14 > A4T14 (Exon2) polymorphisms were associated with higher risk of BC in North Indian population. 相似文献926.
Veerabrahmam Alugolu Satyanarayana Rentala Aruna Lakshmi Komarraju Uma Devi Parimi 《Bioinformation》2013,9(7):334-338
Piperine, a major constituent of Piper nigrum (Black pepper), is one of the well known components in many Ayurvedic
formulations. Piperine is most studied bioenhancer because it inhibits drug metabolizing enzymes in rodents and increases plasma
concentrations of several drugs, including P-glycoprotein substrates. However, there areno evidences on piperine-iron conjugate to
inhibit human CYP450 3A4. We therefore investigated the influence of piperine-Fe conjugate to study the metabolism of iron with
CYP450 3A4. Our in silico results showed that Piperine when conjugated with iron, inhibited activity of CYP450 3A4. This
improved the binding of piperine-Fe conjugate with CYP450 3A4 and increased bioavailability. 相似文献
927.
928.
James J. Burston Devi Rani Sagar Pin Shao Mingfeng Bai Emma King Louis Brailsford Jenna M. Turner Gareth J. Hathway Andrew J. Bennett David A. Walsh David A. Kendall Aron Lichtman Victoria Chapman 《PloS one》2013,8(11)
Osteoarthritis (OA) of the joint is a prevalent disease accompanied by chronic, debilitating pain. Recent clinical evidence has demonstrated that central sensitization contributes to OA pain. An improved understanding of how OA joint pathology impacts upon the central processing of pain is crucial for the identification of novel analgesic targets/new therapeutic strategies.Inhibitory cannabinoid 2 (CB2) receptors attenuate peripheral immune cell function and modulate central neuro-immune responses in models of neurodegeneration. Systemic administration of the CB2 receptor agonist JWH133 attenuated OA-induced pain behaviour, and the changes in circulating pro- and anti-inflammatory cytokines exhibited in this model. Electrophysiological studies revealed that spinal administration of JWH133 inhibited noxious-evoked responses of spinal neurones in the model of OA pain, but not in control rats, indicating a novel spinal role of this target. We further demonstrate dynamic changes in spinal CB2 receptor mRNA and protein expression in an OA pain model. The expression of CB2 receptor protein by both neurones and microglia in the spinal cord was significantly increased in the model of OA. Hallmarks of central sensitization, significant spinal astrogliosis and increases in activity of metalloproteases MMP-2 and MMP-9 in the spinal cord were evident in the model of OA pain. Systemic administration of JWH133 attenuated these markers of central sensitization, providing a neurobiological basis for analgesic effects of the CB2 receptor in this model of OA pain. Analysis of human spinal cord revealed a negative correlation between spinal cord CB2 receptor mRNA and macroscopic knee chondropathy.These data provide new clinically relevant evidence that joint damage and spinal CB2 receptor expression are correlated combined with converging pre-clinical evidence that activation of CB2 receptors inhibits central sensitization and its contribution to the manifestation of chronic OA pain. These findings suggest that targeting CB2 receptors may have therapeutic potential for treating OA pain. 相似文献
929.
C. Subathra Devi Renuka Elizabeth Joseph Harini Saravanan S. Jemimah Naine V. Mohana Srinivansan 《生物学前沿》2013,8(6):632-639
The current work was attempted to isolate and characterize the serratiopeptidase producing Serratia sp. Among the 10 bacterial isolates 7 strains were identified as Serratia sp. Out of 7 strains one showed potent proteolytic activity and selected for further studies. Based on the morphological, biochemical and molecular characterization, the potent isolate (RH03) was identified as Serratia marcescens (GenBank accession number: KC961637) and the strain was designated as Serratia marcescens VITSD2. The production of serratiopeptidase was carried out in trypticase soya broth and the enzyme was partially purified using ammonium sulfate precipitation and dialysis. The specific activity was determined by casein hydrolysis assay and was found to be 12.00, 21.33, and 25.40 units/rag for crude, precipitated and dialysed samples. The molecular weight of the protease was determined by SDS-PAGE and it was found to be 50 kDa. The antibacterial activity of the produced serratiopeptidase showed moderate activity against Pseudomonas aeruginosa MTCC No. 4676 (12 mm) and Escherichia coli MTCC No. 1588 (15 mm). 相似文献
930.
Nef-mediated enhancement of virion infectivity and stimulation of viral replication are fundamental properties of primate lentiviruses 下载免费PDF全文
Münch J Rajan D Schindler M Specht A Rücker E Novembre FJ Nerrienet E Müller-Trutwin MC Peeters M Hahn BH Kirchhoff F 《Journal of virology》2007,81(24):13852-13864
Nef is a multifunctional accessory protein of primate lentiviruses. Recently, it has been shown that the ability of Nef to downmodulate CD4, CD28, and class I major histocompatibility complex is highly conserved between most or all primate lentiviruses, whereas Nef-mediated downregulation of T-cell receptor-CD3 was lost in the lineage that gave rise to human immunodeficiency virus type 1 (HIV-1). Whether or not other Nef activities are preserved between different groups of primate lentiviruses remained to be determined. Here, we show that nef genes from a large variety of HIVs and simian immunodeficiency viruses (SIVs) enhance virion infectivity and stimulate viral replication in human cells and/or in ex vivo infected human lymphoid tissue (HLT). Notably, nef alleles from unpassaged SIVcpz and SIVsmm enhanced viral infectivity, replication, and cytopathicity in cell culture and in ex vivo infected HLT as efficiently as those from HIV-1 and HIV-2, their human counterparts. Furthermore, nef genes from several highly divergent SIVs that have not been found in humans were also highly active in human cells and/or tissues. Thus, most primate lentiviral Nefs enhance virion infectivity and stimulate viral replication. Moreover, our data show that SIVcpz and SIVsmm Nefs do not require adaptive changes to perform these functions in human cells or tissues and support the idea that nef alleles from other primate lentiviruses would also be capable of promoting efficient virus spread in humans. 相似文献