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   2310篇
  免费   135篇
  国内免费   17篇
耳鼻咽喉   52篇
儿科学   86篇
妇产科学   166篇
基础医学   198篇
口腔科学   88篇
临床医学   226篇
内科学   492篇
皮肤病学   35篇
神经病学   139篇
特种医学   67篇
外国民族医学   1篇
外科学   397篇
综合类   53篇
一般理论   1篇
预防医学   106篇
眼科学   60篇
药学   170篇
中国医学   6篇
肿瘤学   119篇
  2023年   24篇
  2022年   68篇
  2021年   125篇
  2020年   58篇
  2019年   80篇
  2018年   87篇
  2017年   44篇
  2016年   61篇
  2015年   79篇
  2014年   97篇
  2013年   128篇
  2012年   174篇
  2011年   197篇
  2010年   118篇
  2009年   101篇
  2008年   166篇
  2007年   143篇
  2006年   112篇
  2005年   102篇
  2004年   107篇
  2003年   66篇
  2002年   68篇
  2001年   24篇
  2000年   24篇
  1999年   19篇
  1998年   12篇
  1997年   5篇
  1996年   6篇
  1995年   5篇
  1994年   8篇
  1992年   11篇
  1991年   12篇
  1989年   6篇
  1988年   11篇
  1987年   10篇
  1986年   7篇
  1985年   8篇
  1983年   3篇
  1982年   4篇
  1980年   6篇
  1978年   4篇
  1977年   4篇
  1976年   3篇
  1975年   6篇
  1974年   11篇
  1973年   12篇
  1972年   5篇
  1971年   5篇
  1970年   3篇
  1969年   6篇
排序方式: 共有2462条查询结果,搜索用时 15 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.
Background  Psoriasis is a chronic disease characterized by abnormal epidermal proliferation, inflammation and angiogenesis. It has been reported that vascular endothelial growth factor (VEGF) is overexpressed in lesional psoriatic skin and its serum levels are significantly elevated in patients with moderate to severe disease.
Objective  This study aims to evaluate the possible role of VEGF in the pathogenesis of psoriasis, and its significance as an indicator of disease severity and control.
Methods  Thirty patients with moderate to severe psoriasis and 10 healthy controls were subjected to baseline evaluation of VEGF. Patients were divided into three groups according to the received treatment: psoralen plus ultraviolet A (PUVA) thrice weekly (group 1), acitretin 50 mg daily (group 2), and combined PUVA twice weekly and acitretin 25 mg daily (group 3).Treatment continued for 16 weeks or up to clinical cure. Every patient was subjected to severity evaluation by Psoriasis Area and Severity Index (PASI) and measurement of serum VEGF before and after treatment.
Results  Mean serum levels of VEGF were significantly elevated in patients (327 ± 66.2 pg/mL) than control subjects (178 ± 83.4 pg/mL). A highly significant correlation was found between VEGF and PASI score, but not with other variables. The best clinical response, the least side-effects and the highest reduction of VEGF serum levels were achieved by the combined therapy.
Conclusion  The present study supported the proposed role of VEGF in the pathogenesis of psoriasis, and suggested that it could serve as a good indicator of disease severity and control.  相似文献   
5.
6.

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   
7.
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   
8.
9.
BACKGROUND: Severe ovarian hyperstimulation syndrome (OHSS) is potentially dangerous. The study aim was to evaluate the efficacy and safety of percutaneous pigtail catheter drainage for the management of ascites complicating severe OHSS. METHODS: This was a prospective trial conducted at a private IVF centre and a tertiary teaching medical centre. A total of 26 patients with severe OHSS was recruited. Patients were divided into two groups. Patients in group 1 (n = 13) were hospitalized, while patients in group 2 (n = 13) were managed on an outpatient basis. A pigtail catheter was inserted under transabdominal ultrasound guidance and kept in place until drainage ceased. The main outcome measures were resolution of OHSS as determined by symptomatology and laboratory values, time to removal of catheter, patient tolerance of the procedure and complication rate. RESULTS: The catheter was successfully placed in all patients following one attempt and was kept in place for a mean +/- SD of 12.9 +/- 4.3 days (range 7-24). Average amount of fluid drained was 11.2 +/- 4.3 l (range: 3.35-18.5). An improvement of symptoms and signs was noted 24-48 h after catheter placement in all patients in both groups. Procedure was well tolerated and no complications reported. CONCLUSIONS: Percutaneous placement of a pigtail catheter is a safe and effective treatment modality for severe OHSS. It may represent an attractive alternative to multiple vaginal or abdominal paracentesis.  相似文献   
10.
The virulence genotype profile and presence of a pathogenicity island(s) (PAI) were studied in 18 strains of F165-positive Escherichia coli originally isolated from diseased calves or piglets. On the basis of their adhesion phenotypes and genotypes, these extraintestinal pathogenic strains were classified into three groups. The F165 fimbrial complex consists of at least two serologically and genetically distinct fimbriae: F165(1) and F165(2). F165(1) is encoded by the foo operon (pap-like), and F165(2) is encoded by fot (sfa related). Strains in group 1 were foo and fot positive, strains in group 2 were foo and afa positive, and strains in group 3 were foo positive only. The strains were tested for the presence of virulence genes found mainly in extraintestinal pathogenic E. coli (ExPEC) strains. Although all the strains were positive for the papA variant encoding F11 fimbriae incD, traT, and papC, the prevalence of virulence genes commonly found in PAIs associated with ExPEC strains was highly variable, with strains of group 2 harboring most of the virulence genes tested. papG allele III was detected in all strains in group 1 and in one strain in group 3. All other strains were negative for the known alleles encoding PapG adhesins. The association of virulence genes with tRNA genes was characterized in these strains by using pulsed-field gel electrophoresis and DNA hybridization. The insertion site of the foo operon was found at the pheU tRNA locus in 16 of the 18 strains and at the selC tRNA locus in the other 2 strains. Furthermore, 8 of the 18 strains harbored a high-pathogenicity island which was inserted in either the asnT or the asnV/U tRNA locus. These results suggest the presence of one or more PAIs in septicemic strains from animals and the association of the foo operon with at least one of these islands. F165-positive strains share certain virulence traits with ExPEC, and most of them are pathogenic in piglets, as tested in experimental infections.  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