全文获取类型
收费全文 | 1526篇 |
免费 | 74篇 |
专业分类
1600篇 |
出版年
2022年 | 10篇 |
2021年 | 21篇 |
2020年 | 15篇 |
2019年 | 17篇 |
2018年 | 24篇 |
2017年 | 28篇 |
2016年 | 28篇 |
2015年 | 43篇 |
2014年 | 53篇 |
2013年 | 75篇 |
2012年 | 105篇 |
2011年 | 81篇 |
2010年 | 61篇 |
2009年 | 35篇 |
2008年 | 58篇 |
2007年 | 68篇 |
2006年 | 59篇 |
2005年 | 52篇 |
2004年 | 40篇 |
2003年 | 42篇 |
2002年 | 37篇 |
2001年 | 49篇 |
2000年 | 40篇 |
1999年 | 41篇 |
1998年 | 18篇 |
1997年 | 17篇 |
1996年 | 13篇 |
1995年 | 18篇 |
1994年 | 18篇 |
1993年 | 10篇 |
1992年 | 25篇 |
1991年 | 38篇 |
1990年 | 34篇 |
1989年 | 29篇 |
1988年 | 31篇 |
1987年 | 26篇 |
1986年 | 15篇 |
1985年 | 12篇 |
1984年 | 12篇 |
1983年 | 12篇 |
1981年 | 13篇 |
1980年 | 10篇 |
1979年 | 19篇 |
1978年 | 12篇 |
1974年 | 9篇 |
1973年 | 15篇 |
1972年 | 11篇 |
1971年 | 15篇 |
1970年 | 13篇 |
1969年 | 14篇 |
排序方式: 共有1600条查询结果,搜索用时 15 毫秒
961.
Sandeep Saxena Sam Dupont Vuppalapaty Meghah Mula G. Meena Lakshmi Sachin K. Singh Cherukuvada V. Brahmendra Swamy Mohammed M. Idris 《Proteomics》2013,13(5):860-865
Ciona intestinalis (the common sea squirt) is the closest living chordate relative to vertebrates with cosmopolitan presence worldwide. It has a relatively simple nervous system and development, making it a widely studied alternative model system in neuroscience and developmental biology. The use of Ciona as a model organism has increased significantly after the draft genome was published. In this study, we describe the first proteome map of the neural complex of C. intestinalis. A total of 544 proteins were identified based on 1DE and 2DE FTMS/ITMSMS analyses. Proteins were annotated against the Ciona database and analyzed to predict their molecular functions, roles in biological processes, and position in constructed network pathways. The identified Ciona neural complex proteome was found to map onto vertebrate nervous system pathways, including cytoskeleton remodeling neurofilaments, cell adhesion through the histamine receptor signaling pathway, γ‐aminobutyric acid‐A receptor life cycle neurophysiological process, glycolysis, and amino acid metabolism. The proteome map of the Ciona neural complex is the first step toward a better understanding of several important processes, including the evolution and regeneration capacity of the Ciona nervous system. 相似文献
962.
963.
Sudheesh Pilakka-Kanthikeel Venkata Subba Rao Atluri Vidya Sagar Shailendra K. Saxena Madhavan Nair 《PloS one》2013,8(4)
Parenteral use of drugs; such as opiates exert immunomodulatory effects and serve as a cofactor in the progression of HIV-1 infection, thereby potentiating HIV related neurotoxicity ultimately leading to progression of NeuroAIDS. Morphine exposure is known to induce apoptosis, down regulate cAMP response element-binding (CREB) expression and decrease in dendritic branching and spine density in cultured cells. Use of neuroprotective agent; brain derived neurotropic factor (BDNF), which protects neurons against these effects, could be of therapeutic benefit in the treatment of opiate addiction. Previous studies have shown that BDNF was not transported through the blood brain barrier (BBB) in-vivo.; and hence it is not effective in-vivo. Therefore development of a drug delivery system that can cross BBB may have significant therapeutic advantage. In the present study, we hypothesized that magnetically guided nanocarrier may provide a viable approach for targeting BDNF across the BBB. We developed a magnetic nanoparticle (MNP) based carrier bound to BDNF and evaluated its efficacy and ability to transmigrate across the BBB using an in-vitro BBB model. The end point determinations of BDNF that crossed BBB were apoptosis, CREB expression and dendritic spine density measurement. We found that transmigrated BDNF was effective in suppressing the morphine induced apoptosis, inducing CREB expression and restoring the spine density. Our results suggest that the developed nanocarrier will provide a potential therapeutic approach to treat opiate addiction, protect neurotoxicity and synaptic density degeneration. 相似文献
964.
Jessica D. Jones Nielsen Anthony A. Laverty Christopher Millett Arch G. Mainous III Azeem Majeed Sonia Saxena 《PloS one》2013,8(6)
Objective
To describe the trends in hospital admissions associated with obesity as a primary diagnosis and comorbidity, and bariatric surgery procedures among children and young people in England.Design
National time trends study of hospital admissions data between 2000 and 2009.Participants
Children and young people aged 5 to 19 years who were admitted to hospital with any diagnosis of obesity.Main outcome measures
Age- and sex-specific admission rates per million children.Results
Between 2000 and 2009, age- and sex-specific hospital admission rates in 5–19 year olds for total obesity-related diagnoses increased more than four-fold from 93.0 (95% CI 86.0 to 100.0) per million children to 414.0 (95% CI 410.7 to 417.5) per million children, largely due to rising admissions where obesity was mentioned as a co-morbidity. The median age of admission to hospital over the study period was 14.0 years; 5,566 (26.7%) admissions were for obesity and 15,319 (73.3%) mentioned obesity as a comorbidity. Admissions were more common in girls than boys (56.2% v 43.8%). The most common reasons for admission where obesity was a comorbid condition were sleep apnoea, asthma, and complications of pregnancy. The number of bariatric surgery procedures has risen from 1 per year in 2000 to 31 in 2009, with the majority were performed in obese girls (75.6%) aged 13–19 years.Conclusions
Hospital admission rates for obesity and related comorbid conditions have increased more than four-fold over the past decade amongst children and young people. Although some of the increase is likely to be due to improved case ascertainment, conditions associated with obesity in children and young people are imposing greater challenges for health care providers in English hospitals. Most inpatient care is directed at dealing with associated conditions rather than primary assessment and management of obesity itself. 相似文献965.
Hosseinzadeh Z Bhavsar SK Shojaiefard M Saxena A Merches K Sopjani M Alesutan I Lang F 《Biochemical and biophysical research communications》2011,(2):456-213
JAK2 (Janus kinase-2) overactivity contributes to survival of tumor cells and the V617FJAK2 mutant is found in the majority of myeloproliferative diseases. Tumor cell survival depends on availability of glucose. Concentrative cellular glucose uptake is accomplished by Na+ coupled glucose transport through SGLT1 (SLC5A1), which may operate against a chemical glucose gradient and may thus be effective even at low extracellular glucose concentrations. The present study thus explored whether JAK2 activates SGLT1. To this end, SGLT1 was expressed in Xenopus oocytes with or without wild type JAK2, V617FJAK2 or inactive K882EJAK2 and electrogenic glucose transport determined by dual electrode voltage clamp experiments. In SGLT1-expressing oocytes but not in oocytes injected with water or JAK2 alone, the addition of glucose to the extracellular bath generated a current (Ig), which was significantly increased following coexpression of JAK2 or V617FJAK2, but not by coexpression of K882EJAK2. Kinetic analysis revealed that coexpression of JAK2 enhanced the maximal transport rate without significantly modifying the affinity of the carrier. The stimulating effect of JAK2 expression was abrogated by preincubation with the JAK2 inhibitor AG490. Chemiluminescence analysis revealed that JAK2 enhanced the carrier protein abundance in the cell membrane. The decline of Ig during inhibition of carrier insertion by brefeldin A was similar in the absence and presence of JAK2. Thus, JAK2 fosters insertion rather than inhibiting retrieval of carrier protein into the cell membrane. In conclusion, JAK2 upregulates SGLT1 activity which may play a role in the effect of JAK2 during ischemia and malignancy. 相似文献
966.
967.
968.
Constant Anatole Pieme Guru Kumar Santosh Emmanuel Mouafo Tekwu Tülin Askun Hatice Aydeniz Jeanne Yonkeu Ngogang Shashi Bhushan Ajit Kumar Saxena 《Biological research》2014,47(1)
Background
Zanthoxylum heitzii is a spice used to prepare several dishes and to treat tumors, syphilis, malaria, cardiac palpitations, urogenital infections in the west region of Cameroon, but the antitumor mechanisms and chemical composition are not yet investigated.This study was aimed to determine the antiproliferative effects of four extracts from the fruits and barks of Zanthoxyllum heitzii (Rutaceae) on apoptosis in human promyelocytic cells, their mechanisms and the chemical composition. The 3-(4, 5-dimethylthiazole-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay was used to determine the fifty percent inhibition (IC50) concentration of the cell lines after treatment. The effect on morphology was observed using a light or fluorescence microscopy. The rate of apoptosis and the cell cycle were measured using flow cytometry (FCM). The phytochemical analysis of the extract was carried with HPLC/MS methods.Results
The phytochemical analysis of the extracts indicated the presence of four known polyphenols (Syringic acid, Juglon, Luteolin and Myricetin) in both fruits and barks of Z. heitzii but in different quantities. Syringic acid and Myricetin concentrations were between 17-21 fold higher in the fruits than the stem bark. Rhamnetin (393.35 μg/mL) and Oleuropein (63.10 μg/mL) were identified only in the stem barks of Z. heitzii. Among the four extracts tested for cytotoxicity properties, only the methanol extract of fruits and barks significantly inhibited cell proliferation of HL-60 cells with IC50 value of 20 μg/mL and 12 μg/mL respectively. HL-60 cells treated with Z. heitzii extracts significantly produced reactive oxygen species (ROS) with concurrent loss of mitochondrial membrane potential (MMP). Modifications in the DNA distribution and enhanced of G1/G0 phase cell cycle arrest were observed in a concentration dependent manner.Conclusions
Polyphenols from Z. heitzii plant exert inhibitory effect on HL-60 cells through the reactive oxygen species (ROS) generation, loss of mitochondrial membrane potential and cell cycle destabilization. 相似文献969.
Objective
To assess whether increased awareness and diagnosis of obstructive sleep apnoea syndrome (OSAS) and national guidance on tonsillectomy for recurrent tonsillitis have influenced the socio-demographic profile of children who underwent tonsillectomy over the last decade.Method
Retrospective time-trends study of Hospital Episodes Statistics data. We examined the age, sex and deprivation level, alongside OSAS diagnoses, among children aged <16 years who underwent (adeno)tonsillectomy in England between 2001/2 and 2011/12.Results
Among children aged <16 years, there were 29,697 and 27,732 (adeno)tonsillectomies performed in 2001/2 and 2011/12, respectively. The median age at (adeno)tonsillectomy decreased from 7 (IQR: 5–11) to 5 (IQR: 4–9) years over the decade. (Adeno)tonsillectomy rates among children aged 4–15 years decreased by 14% from 350 (95%CI: 346–354) in 2001/2 to 300 (95%CI: 296–303) per 100,000 children in 2011/12. However, (adeno)tonsillectomy rates among children aged <4 years increased by 58% from 135 (95%CI: 131–140) to 213 (95%CI 208–219) per 100,000 children in 2001/2 and 2011/2, respectively. OSAS diagnoses among children aged <4 years who underwent surgery increased from 18% to 39% between these study years and the proportion of children aged <4 years with OSAS from the most deprived areas increased from 5% to 12%, respectively.Conclusions
(Adeno)tonsillectomy rates declined among children aged 4–15 years, which reflects national guidelines recommending the restriction of the operation to children with more severe recurrent throat infections. However, (adeno)tonsillectomy rates among pre-school children substantially increased over the past decade and one in five children undergoing the operation was aged <4 years in 2011/12.The increase in surgery rates in younger children is likely to have been driven by increased awareness and detection of OSAS, particularly among children from the most deprived areas. 相似文献970.
Jinping Zhang Jia Wang Lan Pang Guorui Xie Thomas Welte Vandana Saxena Jason Wicker Brian Mann Lynn Soong Alan Barrett Willi Born Rebecca O'Brien Tian Wang 《PloS one》2014,9(9)
γδ T cells express several different toll-like receptor (TLR)s. The role of MyD88- dependent TLR signaling in TCR activation of murine γδ T cells is incompletely defined. Here, we report that Pam3CSK4 (PAM, TLR2 agonist) and CL097 (TLR7 agonist), but not lipopolysaccharide (TLR4 agonist), increased CD69 expression and Th1-type cytokine production upon anti-CD3 stimulation of γδ T cells from young adult mice (6-to 10-week-old). However, these agonists alone did not induce γδ T cell activation. Additionally, we noted that neither PAM nor CL097 synergized with anti-CD3 in inducing CD69 expression on γδ T cells of aged mice (21-to 22-month-old). Compared to young γδ T cells, PAM and CL097 increased Th-1 type cytokine production with a lower magnitude from anti-CD3- stimulated, aged γδ T cells. Vγ1+ and Vγ4+ cells are two subpopulations of splenic γδ T cells. PAM had similar effects in anti-CD3-activated control and Vγ4+ subset- depleted γδ T cells; whereas CL097 induced more IFN-γ production from Vγ4+ subset-depleted γδ T cells than from the control group. Finally, we studied the role of MyD88-dependent TLRs in γδ T cell activation during West Nile virus (WNV) infection. γδ T cell, in particular, Vγ1+ subset expansion was significantly reduced in both MyD88- and TLR7- deficient mice. Treatment with TLR7 agonist induced more Vγ1+ cell expansion in wild-type mice during WNV infection. In summary, these results suggest that MyD88-dependent TLRs provide co-stimulatory signals during TCR activation of γδ T cells and these have differential effects on distinct subsets. 相似文献