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   9634篇
  免费   430篇
  国内免费   35篇
耳鼻咽喉   238篇
儿科学   221篇
妇产科学   131篇
基础医学   1310篇
口腔科学   214篇
临床医学   598篇
内科学   2558篇
皮肤病学   205篇
神经病学   536篇
特种医学   334篇
外科学   1560篇
综合类   47篇
预防医学   385篇
眼科学   110篇
药学   632篇
中国医学   12篇
肿瘤学   1008篇
  2023年   61篇
  2022年   112篇
  2021年   187篇
  2020年   121篇
  2019年   130篇
  2018年   139篇
  2017年   137篇
  2016年   164篇
  2015年   166篇
  2014年   209篇
  2013年   259篇
  2012年   343篇
  2011年   417篇
  2010年   227篇
  2009年   193篇
  2008年   380篇
  2007年   413篇
  2006年   431篇
  2005年   463篇
  2004年   461篇
  2003年   414篇
  2002年   490篇
  2001年   394篇
  2000年   388篇
  1999年   330篇
  1998年   133篇
  1997年   89篇
  1996年   78篇
  1995年   100篇
  1994年   79篇
  1993年   64篇
  1992年   250篇
  1991年   226篇
  1990年   220篇
  1989年   223篇
  1988年   195篇
  1987年   182篇
  1986年   158篇
  1985年   182篇
  1984年   97篇
  1983年   91篇
  1982年   39篇
  1981年   39篇
  1979年   85篇
  1978年   42篇
  1977年   56篇
  1975年   53篇
  1971年   46篇
  1969年   36篇
  1968年   38篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
BACKGROUND: For assessment of cardiac sympathetic nervous activity, the conventional protocol for iodine-123-metaiodobenzylguanidine ((123)I-MIBG) imaging requires several hours. METHODS AND RESULTS: To establish whether it is possible to shorten the conventional (123)I-MIBG imaging protocol, anterior planar imaging was performed in 42 heart failure (HF) patients at 5, 15 and 180 min. The washout rate of (123)I-MIBG from 5 to 15 min (WR5-15 min) was calculated as a novel index. WR5-15 min closely correlated with the conventional washout rate and inversely correlated with the heart to mediastinum ratio. Univariate Cox analysis revealed that rapid WR5-15 min, augmented plasma B-type natriuretic peptide level, and decreased left ventricular ejection fraction (LVEF) were predictors for cardiac events. Multivariate analysis showed WR5-15 min and LVEF were independent predictors. The cardiac event rate was markedly higher (73%) in patients when both WR5-15 min and LVEF were abnormal. CONCLUSIONS: WR5-15 min obtained from anterior planar imaging is useful for evaluating the severity of HF and clinical outcome, and may shorten the cardiac (123)I-MIBG scintigraphy protocol.  相似文献   
992.
BACKGROUND: Familial Mediterranean fever (FMF) is an autosomal recessive disease characterized by recurrent attacks of fever with serosal inflammation. FMF gene (MEFV) mutations have been identified primarily in patients from Mediterranean populations. Although several clinical cases have been reported in Japan, there have been few reports to date on mutation analysis. We studied FMF patients and their relatives to examine the clinical and genetic features of this disease in the Japanese population. METHODS: Twelve Japanese FMF patients who met the Tel Hashomer criteria and a total of 17 relatives from 5 of 10 families underwent molecular genetic studies to detect MEFV mutations. The characteristics of these Japanese FMF patients and geno-phenotypical correlations were examined. RESULTS: Almost all of our patients had been suffering for a long time from fever of unknown origin and one patient also had systemic amyloidosis. In our 12 FMF patients, we detected the substitutions E84K, L110P, E148Q, R761H and M694I. We also newly diagnosed 2 relatives as having FMF based on clinical symptoms and the existence of FMF mutations. One patient was homozygous for E148Q, the patient with systemic amyloidosis was a homozygote for M694I and 4 patients from 3 families were compound heterozygotes for E148Q and M694I. Three patients in one family were compound heterozygotes for E148Q, L110P and M694I. There were 3 patients who were heterozygous for E84K, L110P-E148Q or M694I and had no other nucleotide changes in the exons of MEFV. On the other hand, 2 relatives who had never experienced symptoms of FMF were homozygous for L110P-E148Q as well as compound heterozygous for E148Q/E148Q-R761H. E148Q and M694I were the most frequently detected substitutions in our study. CONCLUSIONS: MEFV mutations occur in Japanese FMF patients though FMF is rare in Japan. The identification of MEFV mutations could be a reliable diagnostic test for FMF. The results of genetic analyses on 14 Japanese FMF patients in this study revealed that E148Q and M694I are frequent alleles.  相似文献   
993.
The Department of Veterans Affairs (VA) has been at the vanguard of information technology (IT) and use of comprehensive electronic health records. Despite the widespread use of health IT in the VA, there are still a variety of key questions that need to be answered in order to maximize the utility of IT to improve patient access to quality services. This paper summarizes the potential of IT to enhance healthcare access, key gaps in current evidence linking IT and access, and methodologic challenges for related research. We also highlight four key issues to be addressed when implementing and evaluating the impact of IT interventions on improving access to quality care: 1) Understanding broader needs/perceptions of the Veteran population and their caregivers regarding use of IT to access healthcare services and related information. 2) Understanding individual provider/clinician needs/perceptions regarding use of IT for patient access to healthcare. 3) System/Organizational issues within the VA and other organizations related to the use of IT to improve access. 4) IT integration and information flow with non-VA entities. While the VA is used as an example, the issues are salient for healthcare systems that are beginning to take advantage of IT solutions.  相似文献   
994.
To examine the prevalence of and risk factors for low bone mineral density (BMD) (osteoporosis or osteopenia) in Japanese female patients with systemic lupus erythematosus (SLE). We performed BMD measurements by dual X-ray absorptiometry at the lumbar spine and the hip and collected basic and lifestyle-related, clinical and treatment characteristics among 58 SLE patients. Odds ratios (ORs) and their 95% confidence intervals (CIs) were assessed for associations between low BMD and selected factors among SLE patients. The mean BMD?±?SD was 0.90?±?0.17?g/cm2 at the lumbar spine and 0.76?±?0.17?g/cm2 at the hip. The prevalence of osteopenia (2.5 SD?<?T score?<?1 SD) was 50.0% and that of osteoporosis (T score?<?2.5 SD) was 13.8% in our SLE patients. After adjustment for age and disease duration, we found the number of deliveries (OR?=?5.58, 95% CI?=?1.31?C26.06; P?=?0.02) to be a risk factor for overall low BMD (T score?<?1 SD) and a maximal dosage of >50?mg/day of oral corticosteroids (OR?=?0.25, 95% CI?=?0.07?C0.91; P?=?0.035) as a preventive factor for low BMD at the lumbar spine. Reduced BMD, especially in spinal trabecular bone, was pronounced in Japanese female patients with SLE, particular in those with a history of delivery. A history of high-dose oral corticosteroids was associated with the preservation of BMD at the lumbar spine, however, further study is needed considering the limited sample size.  相似文献   
995.
Pathological features of primary biliary cirrhosis (PBC) are reviewed. Immune-mediated, non-suppurative cholangitis is the initial lesion and is followed by the gradual and extensive destruction of bile ducts and development of chronic cholestasis. Simultaneously, necro-inflammatory activities of the hepatic parenchyma and limiting plates of milder form develop not infrequently. Eventually, liver fibrosis and cirrhosis develop. A new system applicable to needle liver biopsies in which staging is evaluated using a combination of three factors (fibrosis, cholestasis, and bile duct loss) and necro-inflammatory activities of the bile duct and hepatic parenchyma are graded, is proposed. The clinical and therapeutic evaluation of PBC using this system is warranted.  相似文献   
996.
No epidemiological surveys have examined risk factors related to the death of very low birth weight infants (VLBWIs) in Japan. The objectives of this study were to examine the death rate and fatalities related to complications among VLBWIs, and to analyze factors possibly determining the death of VLBWIs. The subjects of this study were 811 VLBWIs admitted to the Neonatal Care Center of Niigata City General Hospital between April 1987 and March 2003. We obtained information on gender, birth weight, gestational age, Apgar scores, single/multiple pregnancy, postnatal transfer, mode of delivery, complications and outcome (alive or deceased) at the time of discharge from medical records. Of the 811 infants, 98 died prior to discharge (12.1%). Logistic regression analysis showed that independent risk factors for death of VLBWIs were male gender (relative risk [RR]: 2.0), low birth weight (RR: 0.56), necrotizing enterocolitis (RR: 58.0), pulmonary hypoplasia (RR: 37.8), chromosomal abnormalities (RR: 36.3), congenital heart diseases (RR: 9.8), persistent fetal circulation (RR: 9.6), neonatal asphyxia (RR: 6.3) and sepsis (RR: 4.4). The risk for death rises 1.8-fold if birth weight decreases by 100 g. A very high risk of perinatal death is associated with necrotizing enterocolitis, pulmonary hypoplasia or chromosomal abnormalities. The risk of death due to congenital heart diseases or neonatal asphyxia is relatively lower, but the incidences of these two disorders are high (8% and 6%, respectively). From the viewpoint of prophylactic treatment aimed at reducing the death rate of VLBWIs, measures to increase birth weight are of primary importance. Furthermore, early treatment and improved perinatal management of congenital heart diseases and neonatal asphyxia are anticipated to reduce the overall death rate of VLBWIs.  相似文献   
997.
Antiphospholipid antibodies (aPL) have been reported to occur in several conditions other than antiphospholipid syndrome, including infections. We herein report the case of a 21-year-old Japanese woman with Parvovirus B19 infection, who developed multiple pulmonary emboli associated with aPL, a lupus anticoagulant and IgM anticardiolipin antibody. Eight weeks later, antiphospholipid antibodies spontaneously disappeared and normal pulmonary flow was observed. Considering the high prevalence of Parvovirus B19 infection, we should be aware of thrombosis associated with transient aPL antibodies in this infectious disease.  相似文献   
998.
Though stenoses of the descending aorta and its branches are seen with congenital anomalies or systemic inflammation, occlusion of the descending aorta is extremely rare. A patient with an occluded hypoplastic descending thoracic aorta required re-operation because of graft failure between the descending thoracic aorta and the infrarenal abdominal aorta. The etiology of the aortic occlusion in this case is unknown, but inflammation, such as Takayasu disease, is speculated.  相似文献   
999.
Isolated extramedullary (EM) relapses of acute myelogenous leukemia (AML) after allogeneic hematopoietic stem cell transplantation (allo-HSCT) have been reported to be rare, and are usually followed by bone marrow relapses. We report a 49-year-old man with AML with the unfavorable chromosome abnormality 7q-, who was treated by allo-HSCT. Fifteen months after allo-HSCT, the patient initially developed a relapse only in his inguinal lymph nodes, and then bone marrow relapse became evident one month after the EM relapse. Subsequently, the patient received chemotherapy and a second allo-HSCT from another donor, but he suffered another relapse in different EM sites including the skin and central nervous system with a persistently normal marrow. This case is characterized by repeated relapses in isolated EM sites after allo-HSCT and suggests that the anti-leukemic effects of chemotherapy and/or graft-versus-leukemia effects in the EM sites might not be so uniformly effective as that in the marrow. Accordingly, we should be aware that AML relapses can occur repeatedly only in isolated EM sites post allo-HSCT, resulting in treatment failure and a poor prognosis.  相似文献   
1000.
BACKGROUND/AIMS: We investigated whether sentinel lymph node biopsy using dye technique alone is useful or not in decision-making for less invasive surgery in patients with gastric cancer. METHODOLOGY: The subjects were 43 patients who had undergone laparotomy for gastric cancer and consented to undergo sentinel lymph node biopsy using patent blue dye. The patients enrolled were 26 males and 17 females, with a mean age of 62.5 years. The tumor sites were upper third of the stomach in 14, middle third in 16, and lower third in 13 patients. The depth of invasion was mucosa in eight, submucosa in 19, muscularis propria in five, subserosa in five, and serosa in six patients. Total gastrectomy was performed in 12, subtotal gastrectomy in 28, and proximal gastrectomy in three patients. RESULTS: The mean number of sentinel lymph node biopsies per surgery was 3.5 +/- 4.1. We were able to perform blue node biopsy in 40 out of 43 patients, but could not find any blue nodes in three patients. Among the 40 patients in whom blue nodes were identified, 29 patients with no metastasis in blue nodes had no evidence of lymph node metastasis (NO). The depth of invasion was not deeper than subserosa in all these patients. Metastasis was observed in one out of the three patients in whom no blue nodes were found. CONCLUSIONS: When the depth of invasion was not deeper than the subserosa and blue nodes were identified, no metastases in either non-blue nodes or blue nodes could be found in the absence of metastatic blue nodes. Therefore, if the depth of invasion is not deeper than the subserosa in gastric cancer, metastatic search in blue nodes seems sufficient and less invasive surgery can be performed safely. Even when the invasion depth is not deeper than the submucosa, the tumor could be metastatic to Group 2 lymph nodes in patients in whom blue node biopsy revealed metastases. When metastasis is found in lymph nodes by intraoperative frozen section diagnosis, less invasive surgery for gastric cancer is not indicated.  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