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   6929篇
  免费   405篇
  国内免费   99篇
耳鼻咽喉   88篇
儿科学   104篇
妇产科学   130篇
基础医学   719篇
口腔科学   267篇
临床医学   575篇
内科学   2183篇
皮肤病学   86篇
神经病学   596篇
特种医学   247篇
外科学   1164篇
综合类   14篇
一般理论   1篇
预防医学   277篇
眼科学   68篇
药学   328篇
中国医学   6篇
肿瘤学   580篇
  2024年   14篇
  2023年   136篇
  2022年   260篇
  2021年   472篇
  2020年   276篇
  2019年   310篇
  2018年   345篇
  2017年   243篇
  2016年   286篇
  2015年   297篇
  2014年   386篇
  2013年   426篇
  2012年   609篇
  2011年   528篇
  2010年   295篇
  2009年   290篇
  2008年   394篇
  2007年   359篇
  2006年   326篇
  2005年   262篇
  2004年   207篇
  2003年   174篇
  2002年   131篇
  2001年   41篇
  2000年   33篇
  1999年   30篇
  1998年   28篇
  1997年   14篇
  1996年   17篇
  1995年   16篇
  1994年   13篇
  1992年   11篇
  1991年   12篇
  1990年   13篇
  1989年   19篇
  1988年   16篇
  1987年   14篇
  1986年   11篇
  1985年   11篇
  1979年   8篇
  1978年   9篇
  1977年   8篇
  1976年   5篇
  1974年   13篇
  1973年   6篇
  1972年   7篇
  1971年   8篇
  1970年   8篇
  1969年   7篇
  1966年   5篇
排序方式: 共有7433条查询结果,搜索用时 5 毫秒
91.
Autosomal-recessive osteopetrosis is a severe genetic disease caused by osteoclast failure. Approximately 50% of the patients harbor mutations of the ATP6i gene, encoding for the osteoclast-specific a3 subunit of V-ATPase. We found inactivating ATP6i mutations in four patients, and three of these were novel. Patients shared macrocephaly, growth retardation and optic nerve alteration, osteosclerotic and endobone patterns, and high alkaline phosphatase and parathyroid hormone levels. Bone biopsies revealed primary spongiosa lined with active osteoblasts and high numbers of tartrate-resistant acid phosphatase (TRAP)-positive, a3 subunit-negative, morphologically unremarkable osteoclasts, some of which located in shallow Howship lacunae. Scarce hematopoietic cells and abundant fibrous tissue containing TRAP-positive putative osteoclast precursors were noted. In vitro osteoclasts were a3-negative, morphologically normal, with prominent clear zones and actin rings, and TRAP activity more elevated than in control patients. Podosomes, alphaVbeta3 receptor, c-Src, and PYK2 were unremarkable. Consistent with the finding in the bone biopsies, these cells excavated pits faintly stained with toluidine blue, indicating inefficient bone resorption. Bone marrow transplantation was successful in all patients, and posttransplant osteoclasts showed rescue of a3 subunit immunoreactivity.  相似文献   
92.
An antimetastatic role for decorin in breast cancer   总被引:1,自引:0,他引:1  
Decorin, a member of the small leucine-rich proteoglycan gene family, down-regulates members of the ErbB receptor tyrosine kinase family and attenuates their signaling, leading to growth inhibition. We investigated the effects of decorin on the growth of ErbB2-overexpressing mammary carcinoma cells in comparison with AG879, an established ErbB2 kinase inhibitor. Cell proliferation and anchorage-independent growth assays showed that decorin was a potent inhibitor of breast cancer cell growth and a pro-apoptotic agent. When decorin and AG879 were used in combination, the inhibitory effect was synergistic in proliferation assays but only additive in both colony formation and apoptosis assays. Active recombinant human decorin protein core, AG879, or a combination of both was administered systemically to mice bearing orthotopic mammary carcinoma xenografts. Primary tumor growth and metabolism were reduced by approximately 50% by both decorin and AG879. However, no synergism was observed in vivo. Decorin specifically targeted the tumor cells and caused a significant reduction of ErbB2 levels in the tumor xenografts. Most importantly, systemic delivery of decorin prevented metastatic spreading to the lungs, as detected by novel species-specific DNA detection and quantitative assays. In contrast, AG879 failed to have any effect. Our data support a role for decorin as a powerful and effective therapeutic agent against breast cancer due to its inhibition of both primary tumor growth and metastatic spreading.  相似文献   
93.
Gardner syndrome, a variant of familial adenomatous polyposis, is an autosomal dominant genetic disease characterized by the combined presence of multiple intestinal polyps and extraintestinal manifestations. The extraintestinal manifestations include multiple osteomas, connective tissue tumors, thyroid carcinomas, and hypertrophy of the pigmented epithelium of the retina. Osteoma is a benign neoplasm of bone tissue characterized by slow continuous growth that usually affects the long bones and cranial bones and is a major symptom for Gardner syndrome. The authors report the extraintestinal lesions affecting the maxillofacial regions in 2 male patients (father and son) with Gardner syndrome. The presurgical planning and surgical management of these lesions are described.  相似文献   
94.
95.
Contrast induced nephropathy (CIN) is a common complication of coronary angiography/angioplasty. Prevention is the key to reduce the incidence of CIN and it begins with appropriate pre-procedural management. Statins have been shown to possess pleiotropic effects (anti-oxidant, anti-inflammatory and anti-thrombotic properties) and their effects on CIN were assessed in several studies with conflicting results. Aim of this meta-analysis is to evaluate the efficacy of short-term statins for the prevention of CIN in patients undergoing coronary angiography/percutaneous interventions. We performed formal searches of PubMed, EMBASE, Cochrane central register of controlled trials and major international scientific session abstracts from January 1990 to January 2014 of trials which compares short-term statins versus Placebo for the prevention of CIN in patients undergoing coronary angiography/angioplasty. Data regarding study design, statin dose, inclusion/exclusion criteria, number of patients, and clinical outcome was extracted by 2 investigators. Eight trials were included, with a total of 4734 patients. CIN occurred in 79/2,358 patients (3.3 %) treated with statins versus 153/2,376 patients (6.4 %) of the placebo group [OR 95 % CI 0.50 (0.38–0.66), p < 0.00001; p het = 0.39]. Benefits were both observed with high-dose short-term statins [OR 95 % CI 0.44 (0.30–0.65), p < 0.0001; p het = 0.16] and low-dose statins, [OR 95 % CI 0.58 (0.39–0.88), p = 0.010; p het = 0.90]. By meta-regression analysis, no significant relationship was observed between benefits from statin therapy and patient’s risk profile (p = 0.26), LDL cholesterol (p = 0.4), contrast volume (p = 0.94) or diabetes rate (p = 0.38). This meta-analysis showed that among patients undergoing coronary angiography/percutaneous intervention the use of short-term statins reduces the incidence of CIN, and therefore is highly recommended even in patients with low LDL-cholesterol levels.  相似文献   
96.
97.
98.
AIMS: We correlated the finding of cardioinhibitory carotid sinus hypersensitivity (CSH) with that observed during a spontaneous syncopal relapse by means of an implantable loop recorder (ILR). METHODS AND RESULTS: We included 18 consecutive patients with suspected recurrent neurally mediated syncope and positive cardioinhibitory response during carotid sinus massage (max pause 5.5 +/- 1.6 s) who had subsequent documentation of a spontaneous syncope by means of an ILR. They were compared with a 2:1 age- and sex-matched group of 36 patients with a clinical diagnosis of recurrent neurally mediated syncope and negative response to carotid sinus massage, tilt testing and ATP test. Asystole >3 s was observed at the time of the spontaneous syncope in 16 (89%) of CSH patients and in 18 (50%) of the control group (P = 0.007). Sinus arrest was the most frequent finding among CSH patients but not among controls (72 vs. 28%, P = 0.003). After ILR documentation, 14 CSH patients with asystole received dual-chamber pacemaker implantation; during 35 +/- 22 months of follow-up, 2 syncopal episodes recurred in 2 patients (14%), and pre-syncope occurred in another 2 patients (14%). Syncope burden decreased from 1.68 (95% confidence interval 1.66 - 1.70) episodes per patient per year before to 0.04 (0.038-0.042) after pacemaker implant (98% relative risk reduction). CONCLUSIONS: In patients with suspected neurally mediated syncope, the finding of cardioinhibitory CSH predicts an asystolic mechanism at the time of spontaneous syncope and, consequently, suggests a possible benefit of cardiac pacing therapy.  相似文献   
99.
AIM: To evaluate the predictors of 10-year survival of patients with hepatitis C recurrence. METHODS: Data from 358 patients transplanted between 1989 and 2010 in two Italian transplant centers and with evidence of hepatitis C recurrence were analyzed. A χ2, Fisher's exact test and Kruskal Wallis' test were used for categorical and continuous variables, respectively. Survival analysis was performed at 10 years after transplant using the Kaplan-Meier method, and a log-rank test was used to compare groups. A P level less than 0.05 was considered significant for all tests. Multivariate analysis of the predictive role of different variables on 10-year survival was performed by a stepwise Cox logistic regression.RESULTS: The ten-year survival of the entire population was 61.2%. Five groups of patients were identified according to the virological response or lack of a response to antiviral treatment and, among those who were not treated, according to the clinical status(mild hepatitis C recurrence, "too sick to be treated" and patients with comorbidities contraindicating the treatment). While the 10-year survival of treated and untreated patients was not different(59.1% vs 64.7%, P = 0.192), patients with a sustained virological response had a higher 10-year survival rate than both the "non-responders"(84.7% vs 39.8%, P 0.0001) and too sick to be treated(84.7% vs 0%, P 0.0001). Sustained virological responders had a survival rate comparable to patients untreated with mild recurrence(84.7% vs 89.3%). A sustained virological response and young donor age were independent predictors of 10-year survival. CONCLUSION: Sustained virological response significantly increased long-term survival. Awaiting the interferon-free regimen global availability, antiviral treatment might be questionable in selected subjects with mild hepatitis C recurrence.  相似文献   
100.
Background.?The spread of Klebsiella pneumoniae (Kp) strains that produce K. pneumoniae carbapenemases (KPCs) has become a significant problem, and treatment of infections caused by these pathogens is a major challenge for clinicians. Methods.?In this multicenter retrospective cohort study, conducted in 3 large Italian teaching hospitals, we examined 125 patients with bloodstream infections (BSIs) caused by KPC-producing Kp isolates (KPC-Kp) diagnosed between 1 January 2010 and 30 June 2011. The outcome measured was death within 30 days of the first positive blood culture. Survivor and nonsurvivor subgroups were compared to identify predictors of mortality. Results.?The overall 30-day mortality rate was 41.6%. A significantly higher rate was observed among patients treated with monotherapy (54.3% vs 34.1% in those who received combined drug therapy; P?=?.02). In logistic regression analysis, 30-day mortality was independently associated with septic shock at BSI onset (odds ratio [OR]: 7.17; 95% confidence interval [CI]: 1.65-31.03; P?=?.008); inadequate initial antimicrobial therapy (OR: 4.17; 95% CI: 1.61-10.76; P?=?.003); and high APACHE III scores (OR: 1.04; 95% CI: 1.02-1.07; P?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