首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   367篇
  免费   25篇
  国内免费   2篇
  394篇
  2021年   3篇
  2020年   4篇
  2019年   4篇
  2017年   3篇
  2016年   7篇
  2015年   10篇
  2014年   20篇
  2013年   14篇
  2012年   18篇
  2011年   16篇
  2010年   17篇
  2009年   18篇
  2008年   10篇
  2007年   11篇
  2006年   17篇
  2005年   10篇
  2004年   18篇
  2003年   11篇
  2002年   12篇
  2001年   17篇
  2000年   18篇
  1999年   11篇
  1998年   4篇
  1997年   5篇
  1996年   6篇
  1994年   2篇
  1993年   2篇
  1992年   7篇
  1991年   10篇
  1990年   4篇
  1989年   5篇
  1988年   2篇
  1987年   8篇
  1985年   3篇
  1984年   5篇
  1983年   10篇
  1982年   3篇
  1981年   2篇
  1980年   8篇
  1979年   3篇
  1978年   4篇
  1977年   4篇
  1976年   3篇
  1975年   3篇
  1974年   2篇
  1973年   2篇
  1970年   5篇
  1969年   2篇
  1967年   2篇
  1965年   2篇
排序方式: 共有394条查询结果,搜索用时 15 毫秒
1.

Introduction

Left untreated, malignant pleural mesothelioma (MPM) is associated with uniformly poor prognosis. Better survival has been reported with surgery-based multimodality therapy, but to date, no trial has demonstrated survival benefit of surgery over other therapies. We evaluated whether cancer-directed surgery influenced survival independently from other predictors in a large population-based dataset.

Methods

The SEER database was explored from 1973 to 2009 to identify all cases of pathologically-proven MPM. Age, sex, race, year of diagnosis, histology stage, cancer-directed surgery, radiation, and vital status were analyzed. The association between prognostic factors and survival was estimated using Cox regression and propensity matched analysis.

Results

There were 14,228 patients with pathologic diagnosis of MPM. On multivariable analysis, female gender, younger age, early stage, and treatment with surgery were independent predictors of longer survival. In comparison to no treatment, surgery alone was associated with significant improvement in survival [adjusted hazard ratio (adj HR) 0.64 (0.61–0.67)], but not radiation [adj HR 1.15 (1.08–1.23)]. Surgery and radiation combined had similar survival as surgery alone [adj HR 0.69 (0.64–0.76)]. Results were similar when cases diagnosed between 1973 and 1999 were compared to cases diagnosed between 2000 and 2009.

Conclusions

Despite developments in surgical and radiation techniques, the prognosis for MPM patients has not improved over the past 4 decades. Cancer-directed surgery is independently associated with better survival, suggesting that multimodal surgery-based therapy can benefit these patients. Further research in adjuvant treatment is necessary to improve prognosis in this challenging disease.  相似文献   
2.
    
Candida is the most common human fungal pathogen and causes systemic infections that require neutrophils for effective host defense. Humans deficient in the C-type lectin pathway adaptor protein CARD9 develop spontaneous fungal disease that targets the central nervous system (CNS). However, how CARD9 promotes protective antifungal immunity in the CNS remains unclear. Here, we show that a patient with CARD9 deficiency had impaired neutrophil accumulation and induction of neutrophil-recruiting CXC chemokines in the cerebrospinal fluid despite uncontrolled CNS Candida infection. We phenocopied the human susceptibility in Card9-/- mice, which develop uncontrolled brain candidiasis with diminished neutrophil accumulation. The induction of neutrophil-recruiting CXC chemokines is significantly impaired in infected Card9-/- brains, from both myeloid and resident glial cellular sources, whereas cell-intrinsic neutrophil chemotaxis is Card9-independent. Taken together, our data highlight the critical role of CARD9-dependent neutrophil trafficking into the CNS and provide novel insight into the CNS fungal susceptibility of CARD9-deficient humans.  相似文献   
3.
4.
  总被引:2,自引:0,他引:2  
Analysis of 12 polymorphic simple sequence repeats identified in the genome sequence of Phytophthora ramorum, causal agent of 'sudden oak death', revealed genotypic diversity to be significantly higher in nurseries (91% of total) than in forests (18% of total). Our analysis identified only two closely related genotypes in US forests, while the genetic structure of populations from European nurseries was of intermediate complexity, including multiple, closely related genotypes. Multilocus analysis determined populations in US forests reproduce clonally and are likely descendants of a single introduced individual. The 151 isolates analysed clustered in three clades. US forest and European nursery isolates clustered into two distinct clades, while one isolate from a US nursery belonged to a third novel clade. The combined microsatellite, sequencing and morphological analyses suggest the three clades represent distinct evolutionary lineages. All three clades were identified in some US nurseries, emphasizing the role of commercial plant trade in the movement of this pathogen.  相似文献   
5.
Although cardiomyocyte (CM) apoptosis has been well described in both in vitro and in vivo models of ischemic heart disease, the intracellular pathways leading to CM death have not been fully characterized. To define the role of death receptor signaling in CM apoptosis, we constructed recombinant adenoviral vectors carrying wild-type (wt) or dominant negative (dn) forms of the death receptor adaptor protein FADD (Fas-associated death domain protein) and used these vectors to transduce rat neonatal CMs in models of hypoxia- and serum deprivation (SD)-induced apoptosis. The combination of SD and hypoxia induced rapid activation of caspase-3 and -8 as well as DNA fragmentation, reaching a plateau within 4-8 h. Adenoviral expression of FADD-dn inhibited caspase-8 activation as well as hypoxia/SD-induced apoptosis at 24 h in an moi (multiplicity of infection)-dependent manner. In contrast, adenoviral expression of FADD-wt increased apoptosis and caspase-3 activity in CMs under both normoxic and hypoxic conditions. Surprisingly, FADD-dn, as well as the specific caspase-8 inhibitor benzyloxycarbonyl-IETD-fluoromethylketone also inhibited the activation of caspase-9 and -3 in CMs subjected to hypoxia/SD. These data suggest a primary role for FADD/caspase-8 signaling that is necessary and sufficient for apoptosis of CMs subjected to hypoxia/SD.  相似文献   
6.
In this paper we develop a model to describe the coevolution of a two-species predator-victim ecosystem. Evolution among the predators acts to displace the predators' zero growth isocline, J, to the left, whereas victim evolution has the opposite effect. More important, we show that for many such systems, there is a value of J, J1, at which the rate of predator evolution exactly equals the rate of victim evolution. This value of J turns out to be a coevolutionary steady state (CSS) which is stable to perturbations. It is suggested that this analysis permits qualitative understanding of why certain real world predator-prey systems oscillate, whereas others do not.  相似文献   
7.
The central concern of this paper is to illustrate how four apparently unrelated classes of variables — dental, perceptual, ethnic origin, and other — can be comprehended within a single parsimonious space, even though some of the measures were qualitative, others quantitative. Thirty-five hundred Israeli villagers of varied ethnic origin were examined on several aspects of oral epidemiology, a battery of tests relating to estimation of number, and miscellaneous traits, including eye colour, tasting PTC, tongue rolling, etc. Significant differences between the six Jewish groups — Yemen, Cochin, Kurdistan, Libya, Berber, and Djerba — were found in the scores of most variables. By the use of the Smallest Space Analysis, distances were established between the different ethnic groups which took into account the complex interrelations in each of 3,500 individual subjects of all 45 categories of 16 variables. A three-dimensional model of the interrelations between the ethnic groups and the trait categories was constructed from the 45 sets of coordinates which resulted from the iterative computer procedure. The ethnic group pairs at greatest distance from each other were found to be Kurdistan:Cochin, then Kurdistan:Djerba, followed by Djerba:Yemen. It is suggested that multivariate analyses of the type presented here, and including interrelations between genetic markers, anthropometric and behavioral variables, would deepen our understanding of the present structure and possible backgrounds of populations of diverse origins.  相似文献   
8.
Plaster casts of the dentition of 137 Bedouin, mostly members of the Abu Rabiya tribe in the Negev desert, were subjected to odontometric and morphologic analysis. They show a marked sexual dimorphism, very strongly developed maxillary and mandibular first molars and much reduced second molars. They exhibit the characteristics of middle-eastern populations with a rather weak expression of the shovel trait, upper premolars with relatively short BL diameters, a high prevalence of Carabelli's complex on the first maxillary molar and virtually complete absence of the protostylid. In general, the Bedouin have larger teeth than three other ethnic groups living in Israel whose dentitions have been recently investigated. Further similarities and differences are discussed.  相似文献   
9.
  总被引:3,自引:0,他引:3  
Copper, zinc superoxide dismutase (SOD1) is activated in vivo by the copper chaperone for superoxide dismutase (CCS). The molecular mechanisms by which CCS recognizes and docks with SOD1 for metal ion insertion are not well understood. Two models for the oligomerization state during copper transfer have been proposed: a heterodimer comprising one monomer of CCS and one monomer of SOD1 and a dimer of dimers involving interactions between the two homodimers. We have investigated protein-protein complex formation between copper-loaded and apo yeast CCS (yCCS) and yeast SOD1 for both wild-type SOD1 (wtSOD1) and a mutant SOD1 in which copper ligand His 48 has been replaced with phenylalanine (H48F-SOD1). According to gel filtration chromatography, dynamic light scattering, analytical ultracentrifugation, and chemical cross-linking experiments, yCCS and this mutant SOD1 form a complex with the correct molecular mass for a heterodimer. No higher order oligomers were detected. Heterodimer formation is facilitated by the presence of zinc but does not depend on copper loading of yCCS. The complex formed with H48F-SOD1 is more stable than that formed with wtSOD1, suggesting that the latter is a more transient species. Notably, heterodimer formation between copper-loaded yCCS and wtSOD1 is accompanied by SOD1 activation only in the presence of zinc. These findings, taken together with structural, biochemical, and genetic studies, strongly suggest that in vivo copper loading of yeast SOD1 occurs via a heterodimeric intermediate.  相似文献   
10.
Using high-performance liquid chromatography with electrochemical detection to measure substrate disappearance and metabolite accumulation following addition of [Leu]enkephalin to samples prepared from chick brain in vitro, the following were found: 1. [Leu]enkephalin hydrolysis by whole forebrain homogenates is almost solely attributable to aminopeptidase MII activity. 2. [Leu]enkephalin hydrolysis by whole forebrain P2 membrane fractions is attributable to both aminopeptidase MII and dipeptidyl carboxypeptidase activity. 3. Differences are apparent in both [Leu]enkephalin disappearance and Tyr-Gly-Gly accumulation in P2 membrane fractions, but not in homogenate fractions, prepared from several regions of the chick brain.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号