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   23222篇
  免费   1439篇
  国内免费   221篇
耳鼻咽喉   381篇
儿科学   369篇
妇产科学   300篇
基础医学   3935篇
口腔科学   401篇
临床医学   1935篇
内科学   4573篇
皮肤病学   748篇
神经病学   1958篇
特种医学   1325篇
外科学   3088篇
综合类   93篇
一般理论   4篇
预防医学   871篇
眼科学   496篇
药学   2138篇
中国医学   298篇
肿瘤学   1969篇
  2024年   16篇
  2023年   200篇
  2022年   508篇
  2021年   828篇
  2020年   426篇
  2019年   593篇
  2018年   690篇
  2017年   525篇
  2016年   792篇
  2015年   1014篇
  2014年   1159篇
  2013年   1378篇
  2012年   2031篇
  2011年   1948篇
  2010年   1127篇
  2009年   923篇
  2008年   1413篇
  2007年   1306篇
  2006年   1219篇
  2005年   1104篇
  2004年   957篇
  2003年   832篇
  2002年   729篇
  2001年   431篇
  2000年   406篇
  1999年   344篇
  1998年   194篇
  1997年   179篇
  1996年   151篇
  1995年   129篇
  1994年   111篇
  1993年   90篇
  1992年   112篇
  1991年   109篇
  1990年   81篇
  1989年   90篇
  1988年   93篇
  1987年   82篇
  1986年   70篇
  1985年   71篇
  1984年   45篇
  1983年   47篇
  1982年   37篇
  1981年   25篇
  1980年   32篇
  1979年   38篇
  1978年   25篇
  1977年   23篇
  1976年   20篇
  1975年   19篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
Purpose Pseudomembranous colitis is a severe form of antibiotic-associated diarrhea. However, there have been no reports about the factors that make patients with presumed antibiotic-associated diarrhea susceptible to pseudomembranous colitis. This study was designed to determine the clinical risk factors for pseudomembranous colitis among the patients with presumed antibiotic-associated diarrhea. Methods This was a retrospective study of 150 consecutive patients admitted to our institution between January 2000 and December 2004 with a diagnosis of presumed antibiotic-associated diarrhea. All patients underwent sigmoidoscopy or colonoscopy because of diarrhea after administration of antibiotics. Pseudomembranous colitis was confirmed both endoscopically and histologically. Various clinical parameters were compared between the pseudomembranous colitis group and non-pseudomembranous colitis group. Results The mean age of patients was 61 years, and 60 percent (90/150) was female. Pseudomembranous colitis was diagnosed in 53 percent (80/150). On univariate analysis, older than aged 70 years (P = 0.014), antibiotic therapy for more than 15 days (P < 0.0001), hospital stay for more than 20 days (P < 0.0001), number of antibiotics used more than one (P = 0.01), and surgical procedures (P = 0.029) were significant parameters for pseudomembranous colitis. On multivariate analysis, the important clinical risk factors were advanced age (older than aged 70 years; adjusted odds ratio, 2.7; 95 percent confidence interval, 1.208–6.131; P < 0.016) and long hospital stay (more than 20 days; adjusted odds ratio, 5.1; 95 percent confidence interval, 2.1–12.259; P < 0.0001). When both risk factors were present, the positive predictive value of pseudomembranous colitis was 0.86. Conclusions Advanced age and long hospital stay may make patients with presumed antibiotic-associated diarrhea susceptible to pseudomembranous colitis. Therefore, pseudomembranous colitis should be first suspected in cases with presumed antibiotic-associated diarrhea having such risk factors. Poster presentation at the meeting of the Asian-Pacific Digestive Week 2005, Seoul, Republic of Korea, September 25 to 28, 2005.  相似文献   
992.
A 42-year-old man was admitted to our hospital with a history of fever, headache and disorientation. His cerebrospinal fluid revealed eosinophilia and his serum had an antibody against Angiostrongylus cantonensis (A. cantonensis). Then, he was diagnosed as eosinophilic meningoencephalitis caused by A. cantonensis. He was treated with repeated lumbar punctures and oral prednisolone. Although a symptom he had been suffering from at the time of his admission was urinary retention, this symptom disappeared as his general condition improved. Therefore his case was considered to be Elsberg syndrome with eosinophilic meningoencephalitis caused by A. cantonensis.  相似文献   
993.
Splenic pseudocyst is a rare complication of abdominal trauma. Although it is rare, splenic pseudocyst is well-documented in the literature. According to the current classification, approximately 30% of all splenic cysts or pseudocysts result from direct abdominal trauma. In addition, chronic pancreatitis leads to change of nearby organs with possible acute and chronic complications including splenic lesions. This unusual complication can occur in both emergent and non-emergent conditions. The useful diagnostic procedures to assess intrasplenic pseudocyst are sonogram, CT scan, splenic scan, and occasionally angiography. However, definite diagnosis of pseudocyst is possible only after splenectomy when the absence of epithelial lining is confirmed histologically. Splenic pseudocyst requires surgical resection. We experienced a 31-year-old man who confirmed of warmness in the left side of back with left upper quadrant abdominal pain for several months. First impression was splenic lymphangioma based on CT scan and sonogram finding. Splenectomy was performed. Microscopic examination revealed splenic pseudocyst with fibrous capsule without epithelial lining.  相似文献   
994.
995.
Shin MG  Kajigaya S  McCoy JP  Levin BC  Young NS 《Blood》2004,103(2):553-561
Somatic mitochondrial DNA (mtDNA) mutations accumulate with age in postmitotic tissues but have been postulated to be diluted and lost in continually proliferating tissues such as bone marrow (BM). Having observed marked sequence variation among healthy adult individuals' total BM cell mtDNA, we undertook analysis of the mtDNA control region in a total of 611 individual CD34+ clones from 6 adult BM donors and comparison of these results with the sequences from 580 CD34+ clones from 5 umbilical cord blood (CB) samples. On average, 25% (range, 11% to 50%) of individual CD34+ clones from adult BM showed mtDNA heterogeneity, or sequence differences from the aggregate mtDNA sequence of total BM cells of the same individual. In contrast, only 1.6% of single CD34+ clones from CB showed mtDNA sequence variation from the aggregate pattern. Thus, age-dependent accumulation of mtDNA mutations appears relatively common in a mitotically active human tissue and may provide a method to approximate the mutation rate in mammalian cells, to assess the contribution of reactive oxygen species to genomic instability, and for natural "marking" of hematopoietic stem cells; our data also have important implications for the aging process, forensic identifications, and anthropologic conclusions dependent on the mtDNA sequence.  相似文献   
996.
Five recombinant antigens (Ags; 85A, 85B, 85C, superoxide dismutase [SOD], and 35-kDa protein) were purified from Mycobacterium avium subsp. paratuberculosis and evaluated for their ability to stimulate peripheral blood mononuclear cells (PMBCs) from fecal-culture-positive cows (low and medium shedders) and culture-negative healthy cows. Recombinant Ags 85A, 85B, and 85C induced significant lymphocyte proliferation as well as the production of gamma interferon (IFN-gamma), interleukin-2 (IL-2), IL-12, and tumor necrosis factor alpha (TNF-alpha), but not IL-4, from low and medium shedders. The 85 antigen complex did not stimulate PMBC proliferation from culture-negative healthy cows. The 35-kDa protein also induced significant lymphocyte proliferation as well as the production of IFN-gamma and IL-4 from low and medium shedders. CD4(+) T cells and CD25(+) (IL-2R) T cells were stimulated the most by 85A and 85B, while the 35-kDa protein primarily stimulated CD21(+) B cells involved in humoral immune responses. Interestingly, SOD was less immunostimulatory than other antigens but strongly induced gammadelta(+) T cells, which are thought to be important in the early stages of infection, such as pathogen entry. These data provide important insight into how improved vaccines against mycobacterial infections might be constructed.  相似文献   
997.
PurposeGiant cell tumors (GCTs) are common benign primary bone tumors and are well known for their locally aggressive performance and tendency to recur. The purpose of this study was to analyze the effects of denosumab and risk factors for recurrent spinal GCTs.Materials and MethodsWe searched PubMed, EMBASE, Web of Science, and Cochrane Library databases to identify differences between individuals treated with and without denosumab and risk factors for spinal GCT recurrence. Patient data, including age, sex, tumor resection range, location, denosumab use, Campanacci grade, and radiotherapy, were documented. Comparable factors were evaluated using odds ratios (ORs) and weighted mean differences (WMDs) with 95% confidence intervals (CIs).ResultsSixteen studies were included. The overall incidence of spinal GCT recurrence was 29%. Campanacci grade III tumors showed better recurrence outcomes than grades I and II (OR, 16.36; 95% CI, 4.19–63.93; p<0.001). Gross total resection (OR, 0.09; 95% CI, 0.04–0.19; p<0.001), radiotherapy (OR, 0.27; 95% CI, 0.11–0.65; p=0.004), and the use of denosumab during subtotal resection (OR, 2.95; 95% CI, 1.07–8.17; p=0.04) were important factors for reducing recurrence.ConclusionClinicians must consider the effects of gross total resection, radiotherapy use, and denosumab use in cases of subtotal resection during spinal GCT treatment. So far, many researchers have used denosumab in spinal GCT, but none have clearly suggested an endpoint. Most studies, however, recommend using it for more than 6 months.  相似文献   
998.
This article reviews the literature on capillarization of hepatic sinusoids since its discovery in 1963. Liver sinusoidal endothelial cells are uniquely fenestrated and lack an underlying basement membrane. In chronic liver disease, the sinusoids capillarize and transform into systemic capillaries, a process termed capillarization of sinusoids. The histopathology is marked by defenestration, basement membrane formation, and space of Disse fibrogenesis. Capillarized sinusoids compromise the bidirectional exchange of materials between sinusoids and hepatocytes, leading to hepatocellular dysfunction. Sinusoidal capillarization was first described in active cirrhosis of alcoholics in 1963. Since then, it has been found in early and progressive stages of alcoholic hepatic fibrosis before the onset of cirrhosis. The sinusoidal structure is not altered in alcoholic steatosis without fibrosis. Defenestration impairs the ability of the endothelium to filter chylomicron remnants from sinusoids into the Disse's space, contributing to alcohol-induced postprandial hyperlipidemia and possibly atherosclerosis. Ethanol also modulates the fenestration dynamics in animals. In baboons, chronic alcohol consumption diminishes endothelial porosity in concomitance with hepatic fibrogenesis and in rats defenestrates the endothelium in the absence of fibrosis, and sometimes capillarizes the sinusoids. Acute ethanol ingestion enlarges fenestrations in rats and contracts fenestrations in rabbits. In sinusoidal endothelial cell culture, ethanol elicits fenestration dilation, which is likely related to its interaction with fenestration-associated cytoskeleton. Ethanol potentiates sinusoidal injury caused by cocaine, acetaminophen or lipopolysaccharide in mice and rats. Understanding ethanol's mechanisms on pathogenesis of sinusoidal capillarization and fenestration dynamics will lead to development of methods to prevent risks for atherosclerosis in alcoholism.  相似文献   
999.
1000.
Sparganosis is a parasitic infestation of human by plerocercoid larvae. Sparganum is usually reported to be found in the subcutaneous tissues as well as other organs, including scrotum. However, testicular sparganosis is extremely rare, because of strong capsule of tunica albuginea. An urban-living 54-yr-old Korean man presented with left scrotal pain for 6 yr. Both testes look normal physically. Ultrasonography revealed poorly defined, heterogeneous mass with increased echogenicity in the left testis. This case was misdiagnosed as testicular tumor and underwent orchiectomy, but was diagnosed as testicular sparganosis by histopathology. Sparganosis should be included for differential diagnosis of testis tumor in countries where sparganosis is prevalent.

Graphical Abstract

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