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   3729篇
  免费   204篇
  国内免费   23篇
耳鼻咽喉   83篇
儿科学   100篇
妇产科学   104篇
基础医学   580篇
口腔科学   64篇
临床医学   314篇
内科学   788篇
皮肤病学   77篇
神经病学   378篇
特种医学   133篇
外科学   272篇
综合类   24篇
预防医学   280篇
眼科学   66篇
药学   436篇
中国医学   10篇
肿瘤学   247篇
  2024年   4篇
  2023年   48篇
  2022年   188篇
  2021年   275篇
  2020年   94篇
  2019年   145篇
  2018年   160篇
  2017年   116篇
  2016年   140篇
  2015年   129篇
  2014年   177篇
  2013年   235篇
  2012年   314篇
  2011年   295篇
  2010年   163篇
  2009年   138篇
  2008年   182篇
  2007年   237篇
  2006年   227篇
  2005年   193篇
  2004年   155篇
  2003年   115篇
  2002年   104篇
  2001年   17篇
  2000年   14篇
  1999年   10篇
  1998年   8篇
  1997年   9篇
  1996年   5篇
  1995年   6篇
  1993年   2篇
  1992年   4篇
  1990年   5篇
  1989年   4篇
  1988年   2篇
  1987年   2篇
  1986年   5篇
  1984年   2篇
  1980年   3篇
  1978年   2篇
  1977年   1篇
  1976年   2篇
  1975年   2篇
  1974年   2篇
  1973年   2篇
  1972年   3篇
  1969年   3篇
  1968年   1篇
  1967年   1篇
  1966年   1篇
排序方式: 共有3956条查询结果,搜索用时 15 毫秒
951.
Prospective studies have demonstrated that markers of inflammation, such as high-sensitivity C-reactive protein (hsCRP) and fibrinogen, predict future cardiovascular disease risk. However, the association between the hsCRP and fibrinogen levels and the extent of coronary stenosis in patients with coronary artery disease (CAD) remains controversial. The aim of our case-control study was to assess the association of inflammatory markers with the occurrence and extent of CAD. Serum hsCRP and plasma fibrinogen levels were measured in 138 patients with angiographically assessed CAD and in 183 healthy subjects matched according to age and gender. According to the number of significantly stenosed (>or= 50%) vessels, the patients were classified in four groups: those without stenosis (0-vessel disease) and those with 1, 2 or 3-vessel disease. The hsCRP and fibrinogen levels were significantly higher in patients than in controls (p < 0.001). Although the hsCRP and fibrinogen levels tended to increase with the number of stenotic vessels, the differences were only significant for hsCRP (p < 0.01). Regression analysis indicated hsCRP as an independent predictor for the presence (OR = 3.573, p < 0.05) and extent of CAD (beta = 1.095, p < 0.05). In conclusion, the present study is the first report concerning the frequency distribution of hsCRP in Serbian healthy subjects and CAD patients. We have shown that elevated levels of hsCRP are associated with the presence and extent of CAD.  相似文献   
952.
HIV‐1‐specific CD8+ T cells are present in most HIV‐1‐infected people and play an important role in controlling viral replication, but the characteristics of an effective HIV‐specific T‐cell response are largely unknown. The majority of HIV‐2‐infected people behave as long‐term non‐progressors while those who progress to AIDS do so in a manner indistinguishable from HIV‐1. A detailed study of HIV‐2 infection may identify protective immune responses. Robust gag p26‐specific T‐cell responses are elicited during HIV‐2 infection and correlate with control of viremia. In this study, we analyzed features of an HLA‐B*3501‐restricted T‐cell response to HIV‐2 p26 that may contribute to virus control. In contrast to HIV‐1, HIV‐2‐specific T cells are at an early stage of differentiation (CD27+CD28+), a finding that relates directly to CD4+ T‐cell levels and inversely to immune activation. The cells demonstrate IFN‐γ secretion, oligoclonal T‐cell receptor Vβ gene segment usage, exceptional avidity and secretion of pro‐inflammatory cytokines. Despite the potentially strong selection pressure imposed on the virus by these cells, there was no evidence of HIV‐2 sequence evolution. We propose that in chronic HIV‐2 infection, the maintenance of early‐differentiated, highly avid CD8+ T cells could account for the non‐progressive course of disease. Such responses may be desirable from an HIV vaccine.  相似文献   
953.
The aim of this study was to analyze the occurrence of TOP2A gene amplification and chromosome 17 polysomy in patients with early breast cancer and to correlate the status of these alterations with the prognostic significance expressed as patients' clinical features and survival. Such concurrent analyses of TOP2A gene status and chromosome 17 polysomy have not been performed before. Study group included 149 consecutive stage I-III patients administered standard multimodality treatment. TOP2A abnormalities were examined by standard fluorescence in situ hybridization (FISH) and developed by our group quantitative real-time PCR (qPCR). TOP2A amplification and deletion assessed by FISH were found in 23% and 7% of the tumours, respectively, and by qPCR in 31% and 11% of the tumours, respectively. Chromosome 17 polysomy was detected in 40% of the cases. TOP2A amplification (by qPCR) correlated with shorter disease-free survival (p?=?0.03) and overall survival (p?=?0.047), and the prognostic value of TOP2A was confirmed in the multivariate analysis (HR?=?3.22, 95% CI 1.09-9.56, p?=?0.03). TOP2A gene amplification, but not chromosome 17 polysomy, carries negative prognostic information in early breast cancer. Given the aforementioned results, qPCR might serve as a prognostic tool in determining the patient's prognosis.  相似文献   
954.
The aims of this study were to investigate the frequency and prognostic relevance of CD56 expression in patients with acute myeloid leukemia (AML) and to compare the importance of CD56 expression with standard prognostic factors, such as age, leukocytosis, cytogenetic abnormalities and performance status. We analyzed the data of 184 newly diagnosed patients with non-promyelocytic AML and a follow-up of 36 months. The median patient age was 58 years, with a range of 18-79. CD56+ antigen was recorded in 40 patients (21.7%). CD56 + was the most significant risk factor for OS: P = 0.05. The most significant factor for a poor rate of CR was age ≥ 55 years (P = 0.001). CD56 positivity had no significant influence on CR rate, but it was the most significant risk factor for disease-free survival (P = 0.005). The CD56 antigen is an independent prognostic risk factor, and its presence should be measured regularly for a better prognostic assessment of patients with AML.  相似文献   
955.
This single-center study estimated the significance of pretreatment factors, including comorbidities, which may predict outcome in elderly patients with acute myeloid leukemia and determined how poor risk factors may be used as decision criteria for intensity of chemotherapy in this group of patients. Seventy-seven patients aged ≥ 55 years treated under four different regimens were followed up 36 month. Our results suggest that the most significant predictor for poor overall survival is comorbidity, as scored by the Hematopoietic Cell Transplantation Comorbidity Index (HCT-CI), P = 0.008. The most significant predictor for rate of complete remission is serum lactate dehydrogenase (LDH) level, P = 0.049, and the most significant predictor of early death is leucocytosis, P = 0.007. HCT-CI ≥ 3 was the most significant factor for treatment decision making regarding intensity of chemotherapy. The use of standardized comorbidity assessment tools, such as HCT-CI, for elderly patients with AML is practical and can help to improve treatment decision regarding the intensity of chemotherapy.  相似文献   
956.
Pancreatic ductal adenocarcinoma (PDAC) is known for its poor prognosis resulting from being diagnosed at an advanced stage. Accurate early diagnosis and new therapeutic modalities are therefore urgently needed. MicroRNAs (miRNAs), considered a new class of biomarkers and therapeutic targets, may be able to fulfill those needs. Combining tissue microdissection with global miRNA array analyses, cell type-specific miRNA expression profiles were generated for normal pancreatic ductal cells, acinar cells, PDAC cells derived from xenografts and also from macrodissected chronic pancreatitis (CP) tissues. We identified 78 miRNAs differentially expressed between ND and PDAC cells providing new insights into the miRNA-driven pathophysiological mechanisms involved in PDAC development. Having filtered miRNAs which are upregulated in the three pairwise comparisons of PDAC vs. ND, PDAC vs. AZ and PDAC vs. CP, we identified 15 miRNA biomarker candidates including miR-135b. Using relative qRT-PCR to measure miR-135b normalized to miR-24 in 75 FFPE specimens (42 PDAC and 33 CP) covering a broad range of tumor content, we discriminated CP from PDAC with a sensitivity and specificity of 92.9% [95% CI=(80.5, 98.5)] and 93.4% [95% CI=(79.8, 99.3)], respectively. Furthermore, the area under the curve (AUC) value reached of 0.97 was accompanied by positive and negative predictive values of 95% and 91%, respectively. In conclusion, we report pancreatic cell-specific global miRNA profiles, which offer new candidate miRNAs to be exploited for functional studies in PDAC. Furthermore, we provide evidence that miRNAs are well-suited analytes for development of sensitive and specific aid-in-diagnosis tests for PDAC.  相似文献   
957.
958.
A loss of neurons is observed in the hippocampus of many patients with epilepsies of temporal lobe origin. It has been hypothesized that damage limitation or repair, for example using neurotrophic factors (NTFs), may prevent the transformation of a normal tissue into epileptic (epileptogenesis). Here, we used viral vectors to locally supplement two NTFs, fibroblast growth factor–2 (FGF-2) and brain-derived neurotrophic factor (BDNF), when epileptogenic damage was already in place. These vectors were first characterized in vitro, where they increased proliferation of neural progenitors and favored their differentiation into neurons, and they were then tested in a model of status epilepticus-induced neurodegeneration and epileptogenesis. When injected in a lesioned hippocampus, FGF-2/BDNF expressing vectors increased neuronogenesis, embanked neuronal damage, and reduced epileptogenesis. It is concluded that reduction of damage reduces epileptogenesis and that supplementing specific NTFs in lesion areas represents a new approach to the therapy of neuronal damage and of its consequences.  相似文献   
959.
Muscle biopsy is required to provide a definitive diagnosis in many neuromuscular disorders. Biopsy findings may indicate whether the pathological process is of neurogenic or myopathic origin. The muscle biopsy may give important information on the course of the disease (acute or chronic) and on the disease stage and progression. The interpretation of muscle biopsy, including histochemical and ultrastructural analysis, is a key factor in the diagnosis of muscular dystrophies, glycogenoses, inflammatory myopathies and congenital myopathies. An assessment of muscle biopsy on electron microscopy enables a definite diagnosis of oculopharyngeal muscular dystrophy, mitochondrial myopathy or inclusion body myositis. This paper presents an overview of general indications for muscle biopsy, biopsy procedures, as well as transportation and preparation of muscle tissue for final microscopic analysis. The interpretation of specific microscopic findings and a brief discussion on the clinical usefulness of muscle biopsy in the era of molecular diagnosis are also presented.  相似文献   
960.
Background and purposeInflammation plays a prominent role in Alzheimer disease (AD) pathogenesis. Interleukin-6 (IL-6), a pro-inflammatory cytokine, and some genetic variations in the IL-6 gene have been reported to be associated with a risk of AD. However, the results of the conducted studies are equivocal.Material and methodsWe genotyped IL-6 (–174 C/G) and apolipoprotein E gene (APOE) common polymorphisms in a large case-controlled study in a Polish population. We included 361 patients aged ≥ 65 years with AD (mean age 75.8 ± 5.3 years, 232 females [64.3%]) and 200 controls (75.3 ± 7.4 years; 119 females [59.5%]), without any neurological deficit, cognitive complaints or history of neurological diseases. The IL-6 polymorphism was genotyped using TaqMan SNP allelic discrimination by means of an ABI 7900HT (Applied Biosystems, Foster City, CA).ResultsThe distribution of the IL-6 (–174 C/G) genotypes was similar to that in the controls (AD: C/C = 15.79%, C/G = 51.25%, G/G = 32.96% vs. controls: C/C = 21.50%, C/G = 45.50%, G/G = 33.0%, p > 0.05). Our study confirms previous reports that APOE 4 is strongly related to the risk of AD (OR = 6.17; 95% CI: 4.01–9.49). APOE status did not affect the distribution of the studied IL-6 polymorphism.ConclusionIL-6 (–174 C/G) polymorphism is not a risk factor for late onset AD in a Polish population.  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