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   1821篇
  免费   80篇
  国内免费   16篇
耳鼻咽喉   35篇
儿科学   61篇
妇产科学   61篇
基础医学   126篇
口腔科学   33篇
临床医学   174篇
内科学   391篇
皮肤病学   22篇
神经病学   115篇
特种医学   62篇
外国民族医学   3篇
外科学   374篇
综合类   44篇
一般理论   1篇
预防医学   74篇
眼科学   40篇
药学   157篇
中国医学   5篇
肿瘤学   139篇
  2023年   18篇
  2022年   53篇
  2021年   99篇
  2020年   55篇
  2019年   73篇
  2018年   74篇
  2017年   47篇
  2016年   47篇
  2015年   47篇
  2014年   88篇
  2013年   119篇
  2012年   133篇
  2011年   175篇
  2010年   98篇
  2009年   68篇
  2008年   116篇
  2007年   102篇
  2006年   81篇
  2005年   77篇
  2004年   69篇
  2003年   54篇
  2002年   35篇
  2001年   16篇
  2000年   25篇
  1999年   26篇
  1998年   8篇
  1997年   3篇
  1996年   8篇
  1995年   6篇
  1994年   6篇
  1993年   7篇
  1992年   16篇
  1991年   11篇
  1990年   5篇
  1989年   12篇
  1988年   2篇
  1987年   2篇
  1983年   4篇
  1982年   3篇
  1978年   2篇
  1977年   3篇
  1973年   1篇
  1972年   2篇
  1971年   2篇
  1970年   2篇
  1969年   4篇
  1968年   2篇
  1966年   2篇
  1962年   1篇
  1927年   1篇
排序方式: 共有1917条查询结果,搜索用时 46 毫秒
1.
2.

Background

Clear cell renal cell carcinoma (ccRCC) is known to occur across the adult lifetime traversing the spectrum of age-related organismal changes. Little is known as to how the aging process may affect the course of renal cell carcinoma (RCC) and the repertoire of genes involved.

Methods

Using The Cancer Genome Atlas (n?=?436) and Cancer Genomics of the Kidney (n?=?89) datasets, we applied regression analysis to examine associations between patient age and gene expression profiles in ccRCC tumors and normal kidney tissues. Pathway enrichment analysis was performed to identify cellular process that is affected by aging in ccRCC. Moreover, connectivity mapping analysis was used to predict age-dependent response to drug treatments.

Results

Our analysis revealed different age-dependent gene expression spectra in ccRCC and normal kidney tissues. These findings were significant and independently reproducible in both datasets examined. Age up-regulated genes, showing higher expression in older patients, were significantly enriched (false discovery rate <0.05) in normal tissues for pathways associated with immune response and extracellular matrix organization, whereas age up-regulated genes in tumors were enriched for metabolism and oxidation pathways. Strikingly, age down-regulated genes in normal cells were also enriched for metabolism and oxidation, while those in tumors were enriched for extracellular matrix organization. Further in silico analysis of potential drug targets predicted preferential efficacy of Phosphoinositide 3-kinase inhibitor or immunotherapy in association with age.

Conclusion

We report on previously unrecognized associations between age and molecular underpinnings of RCC, including age-associated expression of genes implicated in RCC development or treatment.  相似文献   
3.
4.
5.

Background and Purpose:   

Management of rib fractures constitutes a major part of the trauma workload of any unit. Rib fractures result in disrupted chest wall mechanics and ventilatory insufficiency. The ability of a lung injury scoring system to predict the degree of respiratory dysfunction after rib fractures was evaluated.  相似文献   
6.
A 48‐year‐old male patient with long‐standing ulcerative colitis since February 2001 which was diagnosed by endoscopy, developed acute digital ischemia affecting both hands with fixed colour changes in the left index finger which was followed shortly by digital ulceration. Magnetic resonance angiography (MRA) of both upper limbs showed evidence of vasculitis affecting digital arterioles on both sided and right subclavian occlusion. The patient received pulse methylprednisolone followed by cyclophosphamide pulse therapy, the latter continuing on a monthly basis for 6 months with appreciable improvement and remission of the vasculitic process; follow‐up MRA showed reperfusion of the previously occluded subcalvian artery. To the authors’ knowledge vasculitis complicating the course of ulcerative colitis is a rare association and is only sporadically reported in the literature. This rare entity should be diagnosed early and aggressively treated; MRA is a very promising diagnostic tool that is suitable for both diagnosis and follow‐up of patients with this rare entity.  相似文献   
7.
8.
Using intact ethanol-fixed cytokeratin monoclonal (CAM 5.2) and propidium iodide dual-stained cells, we have performed two-color multiparametric flow cytometric (FCM) DNA analysis and S-phase fraction (SPF) determination on 165 mechanically dissociated breast carcinomas. Sixty-seven patients were axillary node positive, 33 patients node negative; 59 had biopsy only and in 8, FCM was performed on tissue from metastatic lesions. Overall, 62% of the tumors contained aneuploid cell populations. Abnormal cellular DNA content (aneuploidy) was significantly correlated with high nuclear grade (p less than 0.001), lack of estrogen receptors (p less than 0.001), presence of vascular invasion (p less than 0.04), high histologic grade (p less than 0.04), and tumor size (p less than 0.03) but not with patient age (p greater than 0.07) or axillary node status (p greater than 0.50). SPF values derived from ungated histograms had a positively skewed frequency distribution (range 2 to 30%, N = 152) with an overall median of 11% (diploid, 8.9%; aneuploid, 15.7%). Higher SPF values were significantly correlated with aneuploidy (p less than 0.001), presence of necrosis (p less than 0.001), lack of estrogen receptor (p less than 0.0001), high nuclear grade (p less than 0.001), vascular invasion (p less than 0.003), tumor size (p less than 0.006), and high histologic grade (p less than .004) but not the presence of lymph node metastases (p greater than 0.56). Mean SPF values were significantly higher when calculated from cytokeratin gated DNA histograms (14.1% versus 11.5%, p less than 0.001), probably due to exclusion of contaminating stromal/inflammatory cells; and significantly lower when calculated from debris subtracted histograms (7.8% versus 11.4%). Cytokeratin gated and debris subtracted SPF values both had a greater degree of correlation than ungated values with clinicopathologic factors of known prognostic significance.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
9.
Dysfunction of the central dopaminergic neurotransmission has been suggested to play an important role in the etiology of certain neuropsychiatric disorders such as drug abuse. It has been shown that the dopamine D2 receptor (DRD2) gene dysfunction is associated with multi-drug addiction. Addiction to opium is the most common form of drug abuse in Iran. We studied the allelic association between DRD2 Taq I A polymorphism in 100 opium-dependent Iranian patients and 130 unrelated controls. A 310 bp (base pair) region surrounding Taq I site at the DRD2 locus was amplified by polymerase chain reaction (PCR) and the PCR product was incubated with Taq I restriction enzyme. The A1 allele remained intact while the A2 allele was cut. Significant association was observed between A1 allele and addiction in the patients group (P < 0.0001). Moreover, the frequency of A1A1 genotype was significantly higher in opium users than controls (P < 0.0001). Our result indicates that DRD2 might be involved in the pathophysiology of opium addiction.  相似文献   
10.
Hereditary hearing loss (HHL) is a very common disorder. When inherited in an autosomal recessive manner, it typically presents as an isolated finding. Interestingly and unexpectedly, in spite of extreme heterogeneity, mutations in one gene, GJB2, are the most common cause of congenital severe-to-profound deafness in many different populations. In this study, we assessed the contributions made by GJB2 mutations and chromosome 13 g.1777179_2085947del (the deletion more commonly known as del (GJB6-D13S1830) that includes a portion of GJB6 and is hereafter called Delta(GJB6-D13S1830)) to the autosomal recessive non-syndromic deafness (ARNSD) genetic load in Iran. Probands from 664 different nuclear families were investigated. GJB2-related deafness was found in 111 families (16.7%). The carrier frequency of the 35delG mutation showed a geographic variation that is supported by studies in neighboring countries. Delta(GJB6-D13S1830) was not found. Our prevalence data for GJB2-related deafness reveal a geographic pattern that mirrors the south-to-north European gradient and supports a founder effect in southeastern Europe.  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