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   2753篇
  免费   127篇
  国内免费   19篇
耳鼻咽喉   41篇
儿科学   215篇
妇产科学   149篇
基础医学   211篇
口腔科学   91篇
临床医学   251篇
内科学   563篇
皮肤病学   104篇
神经病学   145篇
特种医学   135篇
外科学   523篇
综合类   42篇
预防医学   56篇
眼科学   106篇
药学   137篇
中国医学   4篇
肿瘤学   126篇
  2024年   1篇
  2023年   25篇
  2022年   42篇
  2021年   85篇
  2020年   41篇
  2019年   49篇
  2018年   72篇
  2017年   63篇
  2016年   95篇
  2015年   97篇
  2014年   114篇
  2013年   150篇
  2012年   183篇
  2011年   220篇
  2010年   111篇
  2009年   88篇
  2008年   198篇
  2007年   199篇
  2006年   209篇
  2005年   191篇
  2004年   198篇
  2003年   147篇
  2002年   103篇
  2001年   71篇
  2000年   40篇
  1999年   30篇
  1998年   17篇
  1997年   10篇
  1996年   8篇
  1995年   4篇
  1994年   5篇
  1993年   1篇
  1992年   6篇
  1991年   7篇
  1990年   3篇
  1989年   2篇
  1988年   2篇
  1987年   1篇
  1983年   2篇
  1981年   1篇
  1980年   1篇
  1979年   3篇
  1974年   1篇
  1971年   1篇
  1963年   1篇
  1960年   1篇
排序方式: 共有2899条查询结果,搜索用时 0 毫秒
991.
To evaluate surgically induced astigmatism (SIA) and axis deviation after coaxial microincision superotemporal clear corneal phacoemulsification incision in eyes with differently located steep axis. This prospective, comparative study included four groups of 45 eyes with age-related cataracts; each group underwent 2.2-mm superotemporal clear corneal incision (CCI) cataract surgery. The four groups of patients were divided by location of the steep axis. Groups were matched according to symmetry of the steep axis for both right and left eyes as follows—0°–45° of steep axis for right eyes, and 136°–180° for left eyes (group 1); 46°–90° for right eyes and 91°–135° for left eyes (group 2); 91°–135° for right eyes and 46°–90° for left eyes (group 3); and 136°–180° for right eyes and 0°–45° for left eyes (group 4). Outcome measures included changes in mean total astigmatism, SIA, and axis deviation. Astigmatism was measured by manual keratometry readings before surgery and week 1, week 4, week 8, and week 12 postoperatively. SIA was calculated by the vector analysis (Holladay–Cravy–Koch method). The magnitude of mean total astigmatism was lowest in group 3 and highest in group 1 at week 12. SIA was 0.39 diopters (D), 0.22 D, 0.17 D, and 0.28 D in group 1, group 2, group 3, and group 4, respectively. The change in astigmatic axis deviation was highest in group 3 (23.6 ± 16.6) (P < 0.05). Axis deviation and SIA were stable after week 4. Planning of CCI on or near the steep axis can help decrease corneal astigmatism.  相似文献   
992.

Background and Aim:

Resistive index (RI) is an indirect measurement of blood flow resistance that can be used to evaluate vascular damage in ophthalmologic disease. The purpose of this study was to evaluate the association between RI values of orbital arteries using the color Doppler imaging (CDI) in geriatric hypertensive patients with or without retinopathy.

Setting and Design:

Designed as a cross-sectional study.

Materials and Methods:

We evaluated 60 geriatric patients with hypertension (Group 1) and 30 healthy subjects (Group 2). Further, the patients with hypertension were grouped into two: Group 1a consisted of patients with retinopathy (n = 30), and group 1b consisted of patients without retinopathy (n = 30). The mean RI values of ophthalmic artery (OA), central retinal artery (CRA), and posterior ciliary artery (PCA) were measured using CDI.

Results:

Compared to group 2, group 1 had significantly higher mean resistive index of PCA levels (P = 0.017), whereas there were no statistical difference in mean resistive indexes of OA and CRA (both P > 0.05). Besides, there were no statistical difference in mean resistive indexes of OA, CRA, and PCA between the group 1a and group 1b (P > 0.05 for all). Mean resistive indexes of OA, CRA, and PCA were significantly correlated with the duration of hypertension (r = 0.268, P = 0.038; r = 0.315, P = 0.014; r = 0.324, P = 0.012, respectively).

Conclusions:

Our study indicates that RI might be a useful marker for the ocular hemodynamic of retinal vessels, provides morphologic and vascular information in hypertension and hypertensive retinopathy.  相似文献   
993.

BACKGROUND

Chilblains are rather common in winter months in our country.

OBJECTIVES

Determination of demographical and clinical characteristics of patients presenting with chilblains in Diyarbakir, Turkey. Evaluation of body mass index (BMI) as risk factor for development of chilblains.

METHODS

Sixty-nine patients who were diagnosed as chilblains at our outpatient clinics were included in this study. No exclusion criteria were sought. Demographical data including height and weight and answers to questions related to personal history were recorded. A control group consisting of 108 controls were chosen from among patients presenting with complaints of hair loss. Statistical analyses were conducted using SPSS 17.0.

RESULTS

Of the 69 patients with chilblains, 45 (65.2%) were females and 24 (34.8%) were males. Mean age (±SD) of the patients was 21±9. 71.2% of the patients complained of itching, 51.6% of pain, 31.3% of burning in the lesions. 61.3% of the patients reported recurrence of the lesions every winter season. Mean BMI of the patients was 20.5±2.9. Mean BMI of the controls was 22.4±3.7 and the difference was statistically significant (p=0.01).

CONCLUSIONS

Low BMI may be a risk factor contributing to development of chilblains in persons exposed to cold weather conditions. Apart from external factors, there seems to be a personal tendency to develop lesions, as many patients report recurrences every year. Diagnosis of chilblains requires wariness, as history of cold exposure may not be evident.  相似文献   
994.
The incidence of coronary anomalies (CCAs) in a typical angiographic study was 1.3%.1 Studies have been conducted on CCAs using conventional invasive coronary angiography in highly selected groups of patients but these studies may not reflect the true incidence of CCAs.Although the majority of CCAs are benign and incidentally detected during conventional angiography, certain CCAs may cause syncope, heart failure or sudden death, especially among young athletes.2,3 The US National Registry of Sudden Death in Athletes at the Minneapolis Heart Institute Registry found that CCAs were the second most common cause of sudden cardiac death (out of 17% of the population who died of cardiac-related causes).4Although conventional invasive coronary angiography is considered the gold standard for the diagnosis of CCAs, transthoracic two-dimensional echocardiography, transoesophageal echocardiography, magnetic resonance imaging and multi-slice computed tomography (MSCT) can all identify for diagnosis, CCAs in certain groups of patients.5-10 Transthoracic twodimensional echocardiography may depict the origin of the coronary arteries, especially the left main artery, but successful detection of coronary anomalies depends on the age and size of the patient.5,6Transoesophageal echocardiography has an increased success rate of identifying coronary anomalies in comparison with two-dimensional echocardiography. Nevertheless, the position of the transducer, cardiac motion, and the curvilinear course of the vessel all affect visualisation of coronary anomalies. Moreover, transoesophageal echocardiography is a semi-invasive method and is time consuming.6,7Magnetic resonance (MR) imaging provides an accurate assessment of the course of anomalous coronary arteries.8,9 However, this technique cannot be performed in patients with pacemakers, certain types of arrhythmias or defibrillating devices, and it may be difficult to perform in claustrophobic patients. Furthermore, the spatial resolution of MR imaging is substantially inferior to that of the newest generation of CT scanners.10Myocardial bridging (MB) is defined as the compression of a coronary artery during systole while it is normal in diastole. MB has been linked to serious cardiac events.11 The incidence of myocardial bridging in the population varies substantially according to invasive coronary angiography (13%) and autopsy (15–85%).12,13 The reported incidence of MB has increased up to 44% when using 64-MSCT.14 Because of its ability to cause serious cardiac events, diagnosing MB is clinically important.MSCT is a minimally invasive method that provides excellent temporal and spatial resolution of the coronary arteries. There have been a limited number of studies evaluating CCAs and MB with 64-MSCT. The aim of this study was to assess the incidence of CCAs and MB using 64-MSCT in a relatively large population.  相似文献   
995.
996.

Objective  

To evaluate predictive role of day–3 serum anti-Müllerian hormone (AMH) levels and antral follicle count (AFC) in ovarian hyperstimulation syndrome (OHSS) in patients undergoing IVF/ICSI cycles.  相似文献   
997.

Background

Henoch-Schönlein purpura (HSP) is the most common vasculitis of childhood. HSP can affect multiple organs presenting with a characteristic rash in most of the patients. Familial Mediterranean Fever (FMF) is an inherited inflammatory disease common in mediterranean populations. HSP is the most common vasculitis seen in children with FMF.

Case Presentation

A 16 year old boy was referred with history of abdominal pain lasting for 20 days. He was hospitalized and had appendectomy. Due to the persistence of his abdominal pain after surgery he was admitted to our hospital. His physical examination showed palpable purpuric rashes symmetrically distributed on lower extremities. Abdominal examination revealed periumbilical tenderness. Laboratory tests showed elevated erythrocyte sedimentation rate, Creactive protein and fibrinogen. Urinalysis revealed microscopic hematuria and severe proteinuria. The fecal occult blood testing was positive. Based on these clinic findings, the patient was diagnosed as HSP with renal, gastrointestinal tract and skin involvement. We performed DNA analysis in our patient because he had diagnosis of vasculitis with severe symptoms and found that he was carrying heterozygote P369S mutation.

Conclusion

Our case is noteworthy as it indicates that it may be important not to overlook presence of FMF mutations in patients with a diagnosis of severe vasculitis.  相似文献   
998.
Total parenteral nutrition (TPN) is a revolution in neonatal intensive care unit (NICU) care, but this therapy is not without problems. A 35-week-old, 1300 g female infant was transferred to our NICU because of bilious vomiting and feeding problems. When enteral feeding was started again, a severe condition similar to the previous one developed. On the 24th day, the patient underwent surgery with a diagnosis of Hirschprung's disease. One week before surgery, the parenteral solutions were composed without vitamins because intravenous vitamin supplements suitable for infants were not available. Thereafter, the patient suffered from severe hypoglycaemia, and sepsis started to develop, accompanied by a large anion gap and metabolic acidosis which is severe lactic acidosis refractory to massive doses of bicarbonate. The acidosis improved significantly when the patient was treated with thiamin. Although TPN is life saving in the NICU, meticulous attention must be paid while treating a patient with TPN, and all possible nutrients should be provided. In this report, a case of a preterm newborn requiring a prolonged period of TPN and complicated by serious lactic acidosis is presented and discussed.  相似文献   
999.
Acute generalized exanthematous pustulosis (AGEP) is a rare skin disorder, characterized by acute development of numerous, pin-head sized, nonfollicular pustules on erythematous skin, with high fever and neutrophilia. The condition is frequently caused by hypersensitivity reaction to drugs or viral infections. Diagnosis is established according to clinical and histological criteria. Herein, we report a 17-year-old girl with localized AGEP related to the use of amoxicillin-clavulanate.  相似文献   
1000.
Clinical Rheumatology - Microvascular damage is thought to play a role in the pathogenesis of sarcoidosis. We aimed to evaluate the nailfold capillaroscopy (NVC) pattern to detect microvascular...  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