全文获取类型
收费全文 | 889篇 |
免费 | 108篇 |
专业分类
997篇 |
出版年
2023年 | 8篇 |
2022年 | 4篇 |
2021年 | 21篇 |
2020年 | 11篇 |
2019年 | 16篇 |
2018年 | 12篇 |
2017年 | 12篇 |
2016年 | 16篇 |
2015年 | 41篇 |
2014年 | 31篇 |
2013年 | 35篇 |
2012年 | 46篇 |
2011年 | 56篇 |
2010年 | 32篇 |
2009年 | 15篇 |
2008年 | 37篇 |
2007年 | 39篇 |
2006年 | 39篇 |
2005年 | 30篇 |
2004年 | 27篇 |
2003年 | 35篇 |
2002年 | 17篇 |
2001年 | 28篇 |
2000年 | 27篇 |
1999年 | 38篇 |
1998年 | 9篇 |
1997年 | 9篇 |
1996年 | 12篇 |
1995年 | 12篇 |
1994年 | 14篇 |
1992年 | 32篇 |
1991年 | 21篇 |
1990年 | 18篇 |
1989年 | 19篇 |
1988年 | 14篇 |
1987年 | 13篇 |
1986年 | 19篇 |
1985年 | 23篇 |
1984年 | 16篇 |
1983年 | 5篇 |
1982年 | 13篇 |
1981年 | 7篇 |
1979年 | 8篇 |
1978年 | 4篇 |
1977年 | 7篇 |
1976年 | 6篇 |
1975年 | 5篇 |
1974年 | 6篇 |
1973年 | 3篇 |
1972年 | 4篇 |
排序方式: 共有997条查询结果,搜索用时 0 毫秒
111.
Multiplexed absolute quantification in proteomics using artificial QCAT proteins of concatenated signature peptides 总被引:1,自引:0,他引:1
Absolute quantification in proteomics usually involves simultaneous determination of representative proteolytic peptides and stable isotope-labeled analogs. The principal limitation to widespread implementation of this approach is the availability of standard signature peptides in accurately known amounts. We report the successful design and construction of an artificial gene encoding a concatenation of tryptic peptides (QCAT protein) from several chick (Gallus gallus) skeletal muscle proteins and features for quantification and purification. 相似文献
112.
RECQ1 helicase interacts with human mismatch repair factors that regulate genetic recombination 总被引:1,自引:0,他引:1
Doherty KM Sharma S Uzdilla LA Wilson TM Cui S Vindigni A Brosh RM 《The Journal of biological chemistry》2005,280(30):28085-28094
Understanding the molecular and cellular functions of RecQ helicases has attracted considerable interest since several human diseases characterized by premature aging and/or cancer have been genetically linked to mutations in genes of the RecQ family. Although a human disease has not yet been genetically linked to a mutation in RECQ1, the prominent roles of RecQ helicases in the maintenance of genome stability suggest that RECQ1 helicase is likely to be important in vivo.To acquire a better understanding of RECQ1 cellular and molecular functions, we have investigated its protein interactions. Using a co-immunoprecipitation approach, we have identified several DNA repair factors that are associated with RECQ1 in vivo. Direct physical interaction of these repair factors with RECQ1 was confirmed with purified recombinant proteins. Importantly, RECQ1 stimulates the incision activity of human exonuclease 1 and the mismatch repair recognition complex MSH2/6 stimulates RECQ1 helicase activity. These protein interactions suggest a role of RECQ1 in a pathway involving mismatch repair factors. Regulation of genetic recombination, a proposed role for RecQ helicases, is supported by the identified RECQ1 protein interactions and is discussed. 相似文献
113.
Hybrid zones are natural laboratories offering insights into speciation processes. Narrow hybrid zones are less common in the sea than on land consistent with higher dispersal among marine populations. Acanthochromis polyacanthus is an unusual bony marine fish with philopatric dispersal that exists as allopatric stocks of white, bicoloured and black fish on the Great Barrier Reef (GBR). At two latitudes, different morphs coexist and hybridize at narrow contact zones. Sequence data from mitochondrial Hypervariable Region 1 revealed contrasting patterns of introgression across these zones. At the northern hybrid zone, a single clade of mitochondrial haplotypes was found in all white fish, hybrids and tens of kilometres into pure bicoloured stock. At the southern hybrid zone, there was no introgression of mitochondrial genes into black fish and hybrids shared the bicoloured haplotypes. Based on this asymmetry, we postulate that black fish from the southern GBR have experienced a selective sweep of their mitochondrial genome, which has resulted in almost total reproductive isolation. 相似文献
114.
Margaret R. Dunne Laura Madrigal-Estebas Laura M. Tobin Derek G. Doherty 《Cancer immunology, immunotherapy : CII》2010,59(7):1109-1120
Vγ9Vδ2 T cells respond to pyrophosphate antigens and display potent antitumour activity in vitro. We have investigated the
potential of the most potent phosphoantigen known to activate Vγ9Vδ2 T cells, (E)-4-hydroxy-3-methyl-but-2 enyl pyrophosphate (HMB-PP), as an adjuvant for dendritic cell (DC)-based vaccines. A single stimulation
of peripheral blood mononuclear cells with HMB-PP and IL-2 was sufficient to generate lines of effector memory Vγ9Vδ2 T cells
that retained their cytolytic and cytokine secretion activities. These cells induced differentiation of DC into semi-mature
antigen-presenting cells expressing CD86, CD11c, CD54, HLA-DR, CD83 and CD40, which secreted low levels of bioactive IL-12
but no IL-10. Vγ9Vδ2 T cells also strongly costimulated IL-12 release but inhibited IL-10 production by lipopolysaccharide
(LPS)-stimulated DC. When substituted for Vγ9Vδ2 T cells, IFN-γ did not induce full DC maturation but it augmented IL-12 and
inhibited IL-10 release by LPS-stimulated DC, in a manner similar to HMB-PP-activated Vγ9Vδ2 T cells. Our findings indicate
that Vγ9Vδ2 T cells, stimulated with nanomolar concentrations of HMB-PP, strongly promote T helper type 1 (Th1) responses
through their ability to induce DC maturation and IL-12 secretion. This adjuvant activity may prove useful in DC-based cancer
therapies. 相似文献
115.
Addition of a prominent epitope affects influenza A virus-specific CD8+ T cell immunodominance hierarchies when antigen is limiting 总被引:1,自引:0,他引:1
Jenkins MR Webby R Doherty PC Turner SJ 《Journal of immunology (Baltimore, Md. : 1950)》2006,177(5):2917-2925
A reverse genetics strategy was used to insert the OVA peptide (amino acid sequence SIINFEKL; OVA(257-264)) into the neuraminidase stalk of both the A/PR8 (H1N1) and A/HKx31 (H3N2) influenza A viruses. Initial characterization determined that K(b)OVA257 is presented on targets infected with PR8-OVA and HK-OVA without significantly altering D(b) nucleoprotein (NP)366 presentation. There were similar levels of K(b)OVA257- and D(b)NP366-specific CTL expansion following both primary and secondary intranasal challenge. Interestingly, while variable, the presence of the immunodominant K(b)OVA257-specific response resulted in diminished D(b) acidic polymerase224- and K(b) basic polymerase subunit 1(703)-, but not D(b)NP366-specific responses and didn't alter endogenous influenza A virus-specific immunodominance hierarchies. However, challenging PR8-OVA-primed mice with HK-OVA via the i.p. route, and thereby limiting Ag dose, led to a reduction in the magnitude of all the influenza A virus-specific responses measured. A similar reduction in CTL response to native epitopes was also seen following primary respiratory HK-OVA infection of mice that received substantial numbers of K(b)OVA257-specific TCR transgenic T cells. Thus, during the course of infection, the generation of individual virus-specific CTL responses is independently regulated. However, in cases in which Ag is limiting, or high precursor frequency, the presence of immunodominant CTL responses can impact on the magnitude of other specific populations. Therefore, depending on both the size of the T cell precursor pool and the mode of Ag presentation, the addition of a major epitope can diminish the size of endogenous, influenza-specific CD8+ T cell responses, although never to the point that these are totally compromised. 相似文献
116.
Khatri A Zhang B Doherty E Chapman J Ow K Pwint H Martiniello-Wilks R Russell PJ 《The journal of gene medicine》2006,8(9):1086-1096
BACKGROUND: We aimed to evaluate the efficacy of gene-directed enzyme-prodrug therapy (GDEPT) using cytosine deaminase in combination with uracil phosphoribosyl transferase (CDUPRT) against intraprostatic mouse androgen-refractory prostate (RM1) tumors in immunocompetent mice. The product of the fusion gene, CDUPRT, converts the prodrug, 5-fluorocytosine (5FC), into 5-fluorouracil (5FU) and other cytotoxic metabolites that kill both CDUPRT-expressing and surrounding cells, via a 'bystander effect'. METHODS: Stably transformed andogen-independent mouse prostate cancer (PC) cells, RM1-CDUPRT, -GFP or GFP/LacZ cells were used. To assess the local bystander effects of CDUPRT-GDEPT, immunocompetent C57BL/6 mice implanted with cell mixtures of RM1-GFP/CDUPRT and RM1-GFP cells in different proportions intraprostatically were treated with 5FC. Pseudo-metastases in the lungs were established by a tail vein injection of untransfected RM1 cells. At necropsy, prostate weight/volume and lung colony counts were assessed. Tumors, lymph nodes, spleens and lungs were frozen or fixed for immunohistochemistry. RESULTS: CDUPRT expression in RM1-GFP/CDUPRT cells or tumors was confirmed by enzymic conversion of 5FC into 5FU, using HPLC. Treatment of mice bearing intraprostatic RM1-GFP/CDUPRT tumors with 5FC resulted in complete regression of the tumors. A 'local bystander effect' was seen, even though only 20% of the cells expressed CDUPRT. More importantly a significant reduction in pseudo-metastases of RM1 cells in lungs indicated a 'distant bystander effect'. Immunohistochemical evaluation of the treated tumors showed increased necrosis and apoptosis, with decreased tumor vascularity. There was also a significant increase in tumour-infiltration by macrophages, CD4+ T and natural killer cells. CONCLUSIONS: We conclude that CDUPRT-GDEPT significantly suppressed the aggressive growth of RM1 prostate tumors and lung pseudo-metastases via immune mechanisms involving necrosis and apoptosis. 相似文献
117.
Survival estimates for Royal Terns in southern California 总被引:1,自引:0,他引:1
ABSTRACT. Once the most abundant large tern in California, populations of Royal Terns ( Thalasseus maximus ) are now greatly reduced statewide. However, these terns are still common in southern California where the population appears to be increasing. We estimated survival of this species, for which no robust estimate of survival is available, using mark-resighting data. Apparent survival of birds >3 yr of age was estimated to be ∼0.95; first-year survival was lower at 0.86. The lower survival estimate for first-year birds probably reflects increased mortality, but could also be a function of permanent emigration by individuals in this age class. The adult survival probability is the highest reported among terns and suggests that survival is playing an important role in the recovery of this tern population and that the current population growth is not solely due to immigration. Improvements in resighting protocols, marking technology, and mark-recapture methods are recommended to better use live resighting, dead recovery, and multistate data. 相似文献
118.
119.
Structural determinants of T-cell receptor bias in immunity 总被引:1,自引:0,他引:1
Antigen-specific T-cell responses induced by infection, transplantation, autoimmunity or hypersensitivity are characterized by cells expressing biased profiles of T-cell receptors (TCRs) that are selected from a diverse, naive repertoire. Here, we review the evidence for these TCR biases, focusing on crystallographic analysis of the structural constraints that determine the binding of a TCR to its ligand and the persistence of certain TCRs in an immune repertoire. We discuss the ways in which diversity in a selected TCR repertoire can contribute to protective immunity and the implications of this for vaccine design and immunotherapy. 相似文献
120.
Doherty TA Khorram N Sugimoto K Sheppard D Rosenthal P Cho JY Pham A Miller M Croft M Broide DH 《Journal of immunology (Baltimore, Md. : 1950)》2012,188(6):2622-2629
The fungal allergen, Alternaria, is specifically associated with severe asthma, including life-threatening exacerbations. To better understand the acute innate airway response to Alternaria, naive wild-type (WT) mice were challenged once intranasally with Alternaria. Naive WT mice developed significant bronchoalveolar lavage eosinophilia following Alternaria challenge when analyzed 24 h later. In contrast to Alternaria, neither Aspergillus nor Candida induced bronchoalveolar lavage eosinophilia. Gene microarray analysis of airway epithelial cell brushings demonstrated that Alternaria-challenged naive WT mice had a >20-fold increase in the level of expression of found in inflammatory zone 1 (FIZZ1/Retnla), a resistin-like molecule. Lung immunostaining confirmed strong airway epithelial FIZZ1 expression as early as 3 h after a single Alternaria challenge that persisted for ≥5 d and was significantly reduced in STAT6-deficient, but not protease-activated receptor 2-deficient mice. Bone marrow chimera studies revealed that STAT6 expressed in lung cells was required for epithelial FIZZ1 expression, whereas STAT6 present in bone marrow-derived cells contributed to airway eosinophilia. Studies investigating which cells in the nonchallenged lung bind FIZZ1 demonstrated that CD45(+)CD11c(+) cells (macrophages and dendritic cells), as well as collagen-1-producing CD45(-) cells (fibroblasts), can bind to FIZZ1. Importantly, direct administration of recombinant FIZZ1 to naive WT mice led to airway eosinophilia, peribronchial fibrosis, and increased thickness of the airway epithelium. Thus, Alternaria induces STAT6-dependent acute airway eosinophilia and epithelial FIZZ1 expression that promotes airway fibrosis and epithelial thickness. This may provide some insight into the uniquely pathogenic aspects of Alternaria-associated asthma. 相似文献