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   7237篇
  免费   308篇
  国内免费   52篇
耳鼻咽喉   218篇
儿科学   227篇
妇产科学   381篇
基础医学   514篇
口腔科学   390篇
临床医学   588篇
内科学   1601篇
皮肤病学   91篇
神经病学   477篇
特种医学   294篇
外科学   1419篇
综合类   115篇
预防医学   241篇
眼科学   288篇
药学   379篇
中国医学   43篇
肿瘤学   331篇
  2024年   6篇
  2023年   62篇
  2022年   132篇
  2021年   228篇
  2020年   152篇
  2019年   184篇
  2018年   204篇
  2017年   189篇
  2016年   248篇
  2015年   271篇
  2014年   327篇
  2013年   412篇
  2012年   568篇
  2011年   515篇
  2010年   320篇
  2009年   268篇
  2008年   491篇
  2007年   550篇
  2006年   516篇
  2005年   488篇
  2004年   442篇
  2003年   304篇
  2002年   332篇
  2001年   63篇
  2000年   34篇
  1999年   34篇
  1998年   28篇
  1997年   23篇
  1996年   19篇
  1995年   14篇
  1994年   13篇
  1993年   7篇
  1992年   15篇
  1991年   14篇
  1990年   13篇
  1989年   14篇
  1988年   11篇
  1987年   16篇
  1986年   5篇
  1985年   13篇
  1984年   11篇
  1983年   5篇
  1982年   3篇
  1981年   6篇
  1978年   3篇
  1977年   5篇
  1976年   3篇
  1975年   4篇
  1969年   2篇
  1966年   2篇
排序方式: 共有7597条查询结果,搜索用时 15 毫秒
61.
Introduction: During radiofrequency ablation to encircle or isolate the pulmonary veins (PVs), applications of radiofrequency energy within a PV may result in stenosis. The aim of this study was to determine whether monitoring of real-time impedance facilitates detection of inadvertent catheter movement into a PV.
Methods and Results: In 30 consecutive patients (mean age 53 ± 11 years) who underwent a left atrial ablation procedure, the three-dimensional geometry of the left atrium, the PVs, and their ostia were reconstructed using an electroanatomic mapping system. The PV ostia were identified based on venography, changes in electrogram morphology, and manual and fluoroscopic feedback as the catheter was withdrawn from the PV into the left atrium. Real-time impedance was measured at the ostium, inside the PV at approximately 1 and 3 cm from the ostium, in the left atrial appendage, and at the posterior left atrial wall. There was an impedance gradient from the distal PV (127 ± 30 Ω) to the proximal PV (108 ± 15 Ω) to the ostium (98 ± 11 Ω) in each PV (P < 0.01). There was no significant impedance difference between the ostial and left atrial sites. During applications of radiofrequency energy, movement of the ablation catheter into a PV was accurately detected in 80% of the cases (20) when there was an abrupt increase of ≥4 Ω in real-time impedance.
Conclusion: There is a significant impedance gradient from the distal PV to the left atrium. Continuous monitoring of the real-time impedance facilitates detection of inadvertent catheter movement into a PV during applications of radiofrequency energy. (J Cardiovasc Electrophysiol, Vol. 15, pp. 1-5, June 2004)  相似文献   
62.
BACKGROUND AND AIM OF THE STUDY: Although over 20,000 Edwards-Duromedics valves were implanted worldwide between 1982 and May 1988, use of the valve was voluntarily suspended by the manufacturer in May 1988 on the basis of reported leaflet escapes. In 1990, a modified version was introduced to the market, the Edwards-Tekna. The study aim was to evaluate the short-term outcome with this revised valve. METHODS: Between 1994 and 1998, 137 patients (67 males, 70 females; mean age 36.3+/-9.1 years) underwent heart valve replacement with the Edwards-Tekna prosthesis. Among these patients, 72 had isolated mitral valve replacement, 59 isolated aortic valve replacement, and six double-valve replacement. RESULTS: Early hospital mortality was 0.72% (n = 1). Follow up was 95% complete (129/136 patients discharged from hospital). Mean follow up was 24.9+/-10.5 months (range: 2 to 48 months); total follow up was 282.9 patient-years (pt-yr). Actuarial freedom from complications at two-year follow up and linearized incidence (%/pt-yr) of these events were: late mortality 87.8+/-8.5% (1.77%/pt-yr); thromboembolism 89.8+/-4.9% (2.12%/pt-yr); anticoagulation-related bleeding 97.8+/-1.5% (0.71%/pt-yr); prosthetic valve endocarditis 99.1+/-0.9% (0.35%/pt-yr); valve-related mortality 98.2+/-1.2% (0.71%/pt-yr); and valve-related morbidity and mortality 85.0+/-5.0% (4.24%/pt-yr). There was no structural valve failure such as leaflet escape in this series. Clinically significant hemolysis was not encountered (mean postoperative plasma LDH level 345+/-124 IU/l). Preoperatively, 69% of patients were in NYHA classes III/IV; at two years postoperatively 90% of survivors were in classes I/II. CONCLUSION: The Edwards-Tekna mechanical valve prosthesis has shown excellent overall clinical performance in the short term, though long-term data are needed to confirm its durability.  相似文献   
63.
OBJECTIVES: The purpose of our study was to evaluate the significance of polymorphisms in HLA class II genes in coronary artery ectasia (CAE) patients. METHODS AND RESULTS: Twenty-six patients with CAE without associated cardiac defects were enrolled in the study. CAE was defined as luminal dilation of 1.5- to 2.0-fold of normal limits. Ninety-five healthy subjects who were donors for different organ transplantations, were chosen as control group. Physical examination, electrocardiography and chest X-ray were completely normal in these cases. Both the patients and the control group were screened and compared for their HLA class II genotypes. HLA-DR B1*13, DR16, DQ2 and DQ5 genotypes were significantly more frequent in the patient group.When the known risk factors of coronary heart disease were compared in the patients carrying these genotypes with the non-carrying group, no significant differences were encountered. CONCLUSIONS: HLA-DR B1*13, DR16, DQ2 and DQ5 may be associated with the pathogenesis and increase the risk of CAE.  相似文献   
64.
Maternal smoking is considered to be a risk factor for low birth weight. It is hypothesized that alteration in leptin concentration may be associated with reduced fetal growth. In this study, we assess the effect of smoking during pregnancy on maternal and neonatal serum leptin concentrations, and also on breast milk leptin levels. When the infants were brought to routine physical examination at 7 days old, blood samples and breast milk specimens were taken for leptin measurement from mothers who smoked during pregnancy and their newborns. Nonsmoking mothers and their infants were recruited randomly over the same period as a control group. Maternal age, number of pregnancy, weight of the mothers, birth weight, and gestational age of the infants were similar in both groups (p > 0.05). There was no significant difference between groups in maternal serum and breast milk leptin levels (p = 0.14 and p = 0.96, respectively). However, serum leptin levels were found significantly lower in neonates born to smoking mothers compared with infants born to nonsmoking mothers (p = 0.02). Our findings suggest that maternal smoking dose not have an effect on maternal serum and breast milk leptin levels but decreases neonatal serum leptin concentration independent of birth weight.  相似文献   
65.
BackgroundChildren who inhabit the same house with tuberculosis (TB) patients are at high risk for infection and illness with TB. Nutritional status (stunting) in children is related to the child's ability to withstand MTB (Mycobacterium Tuberculosis). This study aims to estimated the prevalence of tuberculosis infection and its relationship to stunting in children (under five years) with household contact (HHC) with new TB cases.MethodsA cross-sectional design was implemented. Conducted in July 2018–April 2019 at 13 Public Health Center in Makassar City. The sample size was calculated using one sample situation-about precision formula. Samples were children under five who had contact with new diagnosed TB cases. Tuberculosis infection was measured by TST (tuberculin skin test). Logistic regression with causal model to examine TB infection relationship with stunting and covariate variable, analyzed using Stata/MP 13.0 software.ResultsOne hundred twenty-six (126) eligible children. Prevalence of tuberculosis infection was 38.10%. Frequency of stunted was 31 children (24.60%). Stunted nutritional status (aPR): 2.36, 95% CI 1.60–3.44), boys (aPR: 1.47, 95% CI 0.96–2.25), not getting BCG immunization (aPR: 1.58, 95%) CI 0.89–2.82), and high contact intensity (aPR: 2.62, 95% CI 1.10–6.22) best predicted the tuberculosis infection in children with TB case household contacts with a model contribution of 64%.ConclusionStunted nutritional status (moderate and severe), boys, not getting BCG immunization, and high contact intensity are the determinants of TB infection transmission in children HHC with TB. Children under five years of age who have close contact with TB cases should be targeted for priority interventions to prevent the transmission of TB infection and progressing to TB cases.  相似文献   
66.
This study was conducted to clarify the role of efflux transporter MRP2 in acetaminophen-induced hepatotoxicity in cats. Sixteen mixed bred male cats and four liver samples from mixed breed male dogs were used. The cats were assigned into four groups (n?=?4), received saline and 2, 10 and 50?mg/kg doses of acetaminophen orally for 14 days. Unlike the intact dogs, the MRP2 was not detectable in control cats. MRP2 at mRNA level was expressed in the liver of cats, which received the medium and high doses. Data suggest that the MRP2 expression may involve in the acetaminophen-induced hepatotoxicity in cats.  相似文献   
67.
Metabolic Brain Disease - Gaucher disease type 2 is the most progressive and the rarest form of Gaucher disease, defined as the acute neuronopathic type. We presented two GD2 patients who died...  相似文献   
68.
The aim of this study was to evaluate the histopathological and apoptotic changes occurring in the rat ipsilateral and contralateral testes, after experimental spermatic cord torsion, and to explore and the role of poly(ADP‐ribose) polymerase (PARP) cleavage in testicular torsion–detorsion injury. A total of 37 Wistar albino rats were subjected to 720° unilateral spermatic cord torsion for 1, 2 and 4 h, followed by 4‐h reperfusion, or else to a sham operation (control group). Histology of the testicle was evaluated using haematoxylin–eosin (H&E) staining and Johnsen's scoring system. Germ cell apoptosis was evaluated via active caspase‐3 immunostaining, and PARP expression levels were evaluated via Western blotting. The mean Johnsen's tubular biopsy scores (JTBS) of the ipsilateral testicles were lower for all torsion groups than for the controls (P < 0.05), but the JTBS of the contralateral testicles were only lower in the 4‐h torsion group (P < 0.05). The mean apoptosis score (AS) of the ipsilateral and contralateral testicles was significantly higher in the torsion groups than in the sham group. AS increased correlatively with torsion time, in both testicles. The effect of testicular torsion on PARP cleavage was time dependent, with the highest effect observed after 4 h of testicular torsion (P < 0.05). Testicular torsion caused time‐dependent histological changes, apoptosis and increases in PARP cleavage. Our results suggest that testicular torsion–detorsion injury caused cell damage and germ cell apoptosis that apparently involved cleavage of PARP. Increased PARP cleavage could, in turn, lead to enhanced apoptosis.  相似文献   
69.

Background:

Polyethylene glycol (PEG) is often considered as the first-line treatment for functional constipation in children. Descurainia sophia (L.) Webb et Berth (D. sophia) is a safe recommended medicine in Iranian folk and Traditional Persian Medicine for the treatment of constipation.

Objectives:

To clinically compare D. sophia with PEG 4000 (without electrolyte) in pediatric constipation and to assess its efficacy and side effects.

Patients and Methods:

120 patients aged 2 - 12 years with constipation for at least 3 months were included in an 8 weeks lasting randomized controlled trial within two parallel-groups. Children received either PEG, 0.4 g/kg/day, or D. sophia seeds, 2 grams (for children aged 2 - 4 years) and 3 grams (for those aged > 4 years) per day.

Results:

A total of 109 patients completed the study (56 in D. sophia and 53 in PEG group). At the end of the study, 36 (64.3%) patients in D. sophia group and 29 (54.7%) in PEG group were out of Rome III criteria (P = 0.205). Median weekly stool frequency in 0, 1, 2, 3 weeks of the treatment was found to be 2, 5, 5, 5 in D. sophia and 3, 4, 4, 5 in PEG group (P = 0.139, 0.076, 0.844, 0.294), respectively. The number of patients who suffered flatulence was less (5, 8.9%) in D. sophia group as compared to PEG group (6, 11.3%) at the end of the trial (P = 0.461). D. sophia taste was less tolerated.

Conclusions:

D. sophia is introduced as a cheap and available medication which can be applied as a safe alternative to conventional PEG in the management of pediatric chronic functional constipation.  相似文献   
70.
Delayed diagnosis of tuberculous arthritis   总被引:2,自引:0,他引:2  
Monoarticular tuberculosis (TB) affecting the knee is rare in all forms of TB (0.1-0.3%). We present the case of a patient with tuberculous arthritis in whom the diagnosis was belated due to a lack of familiarity with the disease; here, we emphasize the difficulties associated with the diagnosing joint TB. A 20-year-old man was referred to our department due to swelling of the right knee and the presence of persistent, mild pain for 4 years. The lack of systemic evidence of this disease, the indolent course of disease, and the presence of non-specific symptoms renders early recognition of this disease difficult. Furthermore, in cases in which a diagnosis cannot be reached simply by culturing the synovial fluid, synovial biopsy cultures should be considered in the diagnostic process, due to the high rate of positivity of such cultures. The diagnosis and treatment of articular TB are both urgent matters; surgical debridement and strict adherence to antituberculous chemotherapy tend to yield a satisfactory functional outcome.  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