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   1636篇
  免费   99篇
  国内免费   5篇
耳鼻咽喉   32篇
儿科学   52篇
妇产科学   37篇
基础医学   199篇
口腔科学   41篇
临床医学   86篇
内科学   358篇
皮肤病学   93篇
神经病学   106篇
特种医学   63篇
外科学   270篇
综合类   4篇
一般理论   1篇
预防医学   118篇
眼科学   17篇
药学   85篇
肿瘤学   178篇
  2023年   9篇
  2022年   11篇
  2021年   37篇
  2020年   10篇
  2019年   38篇
  2018年   44篇
  2017年   25篇
  2016年   25篇
  2015年   32篇
  2014年   43篇
  2013年   82篇
  2012年   86篇
  2011年   114篇
  2010年   62篇
  2009年   63篇
  2008年   83篇
  2007年   90篇
  2006年   80篇
  2005年   101篇
  2004年   92篇
  2003年   103篇
  2002年   99篇
  2001年   80篇
  2000年   63篇
  1999年   80篇
  1998年   22篇
  1997年   15篇
  1996年   8篇
  1995年   17篇
  1994年   7篇
  1993年   8篇
  1992年   24篇
  1991年   20篇
  1990年   16篇
  1989年   9篇
  1988年   6篇
  1987年   7篇
  1986年   4篇
  1985年   3篇
  1984年   2篇
  1980年   2篇
  1979年   1篇
  1977年   1篇
  1976年   1篇
  1974年   1篇
  1973年   1篇
  1970年   2篇
  1969年   2篇
  1967年   4篇
  1963年   1篇
排序方式: 共有1740条查询结果,搜索用时 0 毫秒
81.
Anderson-Fabry disease (AFd) is an X-linked metabolic disease with clinical manifestations secondary to accumulation of glycosphingolipids in various tissues. We report the first case in which a patient with renal variant of AFd and chronic renal failure developed bilateral conventional renal cell carcinoma. His metabolic disorder was diagnosed only after histopathologic study of the kidney specimen resected because of the tumoral lesion. There is no clear etiologic relation between the metabolic and neoplastic disease. As AFd is not common or well known and its clinical manifestations tend to be nonspecific, the disorder is often unrecognized, misdiagnosed, or diagnosed late in life. The pathologist should be aware of this disorder when evaluating a kidney specimen from patients with chronic renal failure of unknown cause.  相似文献   
82.
83.
Summary. The degeneration of nigral dopaminergic neurons in Parkinson’s disease is believed to be associated with a glial reaction and inflammatory changes. In turn, local factors may induce changes in vascularization and contribute to neuronal vulnerability. Among these factors, Vascular Endothelial Growth Factor (VEGF) is released in adults under pathological conditions and is thought to induce angiogenesis.In order to determine whether changes in brain vasculature are observed in the affected brain regions in parkinsonism, we quantitatively analysed the VEGF-expressing cells and blood vessels in the substantia nigra of monkeys rendered parkinsonian by MPTP injection and compared the results with those obtained in control monkeys.Using stereological methods, we observed an increase in the number of VEGF-expressing neurons and an increase of the number of blood vessels and their volume occupying the substantia nigra pars compacta of monkeys rendered parkinsonian by chronic MPTP intoxication. These changes in vascularization may therefore modify the neuronal availability of blood nutrients, blood cells or toxic substances and neuronal susceptibility to parkinsonism.  相似文献   
84.
The neural basis underlying the orienting response has been thoroughly studied in frontal-eyed mammals. However, in non-mammalian species, including fish, it remains almost unknown. Therefore, we studied the contribution of the optic tectum and the mesencephalic reticular formation to the performance of the orienting response in goldfish, using behavioural, physiological, and anatomical tracer techniques. The appearance of a visual stimulus (a pellet of food) in the environment of a goldfish evoked a turn of the body to reorient the line of sight. Left-tectal lobe ablation abolished the orienting turn response towards the contralateral hemifield. Electrical microstimulation of the optic tectum suggested the presence of a motor map, which is in correspondence with the overlying visual representation, as previously reported in other vertebrates. The tracer biotin-dextran amine was injected into different functionally identified tectal zones. The results showed that rostral and caudal poles of the mesencephalic reticular formation receive outflow mainly from the rostral and caudal tectal poles, respectively. This suggests that the tectal wiring with downstream structures is site-dependent. Furthermore, the electrical activation of rostral and caudal mesencephalic reticular formation revealed a different contribution to vertical and horizontal orienting eye movements. We conclude that the basic neural system coding the orienting response appears early in phylogenesis, although some specific characteristics are selected by adaptive pressure.  相似文献   
85.
86.
Endometriosis affecting the urinary tract is very rare and the most common site of involvement is urinary bladder. The clinical features are urgency and frequency, hipogastric pain and hematuria. Cistoscopic examination is the most valuable diagnostic test but definitive diagnosis requires histologic confirmation. We report 2 cases of endometriosis in 2 young women, one with previously cesarean section, in which surgical treatment was effective. After 1 and 3 years of follow-up respectively the patients remain assymptomatic.  相似文献   
87.
In this study we demonstrated that significant egress of FDG from myocardium occurs within the first hour after tracer injection leading to nonlinear Patlak plots. There are also significant amounts of acidic FDG metabolites present in the blood. However, the impact of these metabolites on the estimates of myocardial glucose utilization (MGU) is negligible. Although further studies will be required to elucidate the reason for the egress of tracer from myocardium, not accounting for it will result in erroneous estimates of MGU.  相似文献   
88.
Background. Aberrations of the p53 gene and overexpression of its protein are widely recognized markers of malignancy including oral squamous cell carcinomas. This study was performed to evaluate the relationship of immunoexpression of p53 protein in series of 91 squamous cell carcinomas of the oral cavity with clinicopathologic parameters and to investigate whether p53 immunoexpression might influence the clinical outcome of the disease. Methods. From a group of 287 consecutive patients, 91 surgically treated ones were randomly selected. P53 protein expression was investigated by means of immunohistochemistry. Clinical and histopathologic data were gathered, and the patient survival was analyzed. Results. Of the oral carcinomas, 52.7% (n = 48) overexpressed p53, using a threshold of 10% stained cell nuclei. There was a negative correlation of p53 immunoexpression with a histologic grade of differentiation (r = ?0.236, p = .06) but not with clinical variables. Overall survival rate was 59% at 5 years. In univariate analysis, tumor size, node status, and advanced clinical stage were significantly associated with shortened overall survival. In patients without neck node metastases, p53 showed a strong correlation with survival (p = .01). In multivariate analysis performed only on N0 patients, tumor extension and p53 immunoexpression were found to be the only independent prognostic parameters with relative risks of 1.9 and 4.3, respectively. Conclusions. A strong relationship was observed between p53 immunoexpression and poor prognosis in patients with oral squamous cell carcinomas without neck node metastases. © 2004 Wiley Periodicals, Inc. Head Neck 26: 22–30, 2004  相似文献   
89.
We report on a patient with a full monosomy 21 (FM21) prenatally diagnosed in cord fetal blood, and subsequently confirmed in other tissues. Subtle chromosomal translocations of chromosome 21, were ruled-out by FISH using both painting and 21q telomeric probes. Microsatellites analysis demonstrated the paternal origin of the single chromosome. The propositus showed at 32 weeks of gestation a severe intrauterine growth retardation and microcephaly. He was born with multiple congenital malformations, hypotonia, microcephaly, bilateral microphthalmia (more severe on the left), facial dysmorphism, agenesis of the external auditory meatus, redundant skin in the neck, narrow chest, flat scrotum, cryptorchydism, hypospadias, micropene, camptodactyly, nail hypoplasia, and abnormal palmar and plantar creases. The patient died in the first day of life. At necropsy, micrencephaly, semilobar holoprosencephaly, polimicrogyria, ocular abnormalities, skeletal anomalies, congenital heart disease, and agenesis of right kidney were also observed. To our best knowledge, this case is one of the most completely patient studied with FM21.  相似文献   
90.
Liver cirrhosis main related to hepatitis C virus constitutes the main indication of liver transplantation in Europe and the USA, representing as many as 50% of the indications in adults, while cirrhosis associated with hepatitis B virus represents around 10%. The indications for transplantation in patients with infection by both viruses are fulminant hepatitis, decompensated cirrhosis and hepatocellular carcinoma. Both injections may relapse after transplantation. The evolution of the relapse in the graft is variable and can include non-significant alterations of the liver junction tests, chronic active hepatitis and cirrhosis. Less frequently, a particularly severe form called "fibrosing cholestatic hepatitis" can develop, which rapidly evolve to graft failure. The immunoglobin against the B virus and lamivudine reduce the risk of reinfection. The principal factor associated with reinfection is active viral replication before the transplantation, thus it is considered a contraindication for liver transplantation. INF-alpha has been used in the treatment of hepatitis B virus reinfection with discouraging results. More recently, lamivudine and adefovir have been used. Post-transplantation recurrence of hepatitis C is universal and its evolution towards cirrhosis is more rapid than in immunocompetent patients, with graft dysfunction being the most frequent cause of mortality and of indication for retransplantation. Different factors have been related to the severity of the recurrence including factors related to the donor, the recipient, the virus, immunosuppression and surgery. There are no preventive treatments against recurrence of post-transplantation hepatitis C. In the treatment of the hepatitis C virus recurrence, INF-alpha and rivabirin have been used in single form or in combination with variable results, with the combined therapy being more effective. Recently, encouraging results have been described with the combination of pegylated interferon and rivabirin without a higher incidence of rejection. Finally, the results of retransplantation in patients with recurrent hepatitis B or C have not been encouraging.  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