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   3656篇
  免费   261篇
  国内免费   27篇
耳鼻咽喉   19篇
儿科学   188篇
妇产科学   168篇
基础医学   426篇
口腔科学   112篇
临床医学   310篇
内科学   705篇
皮肤病学   64篇
神经病学   193篇
特种医学   229篇
外科学   556篇
综合类   70篇
预防医学   210篇
眼科学   132篇
药学   255篇
中国医学   29篇
肿瘤学   278篇
  2023年   32篇
  2022年   32篇
  2021年   125篇
  2020年   68篇
  2019年   81篇
  2018年   98篇
  2017年   79篇
  2016年   74篇
  2015年   86篇
  2014年   125篇
  2013年   131篇
  2012年   243篇
  2011年   267篇
  2010年   141篇
  2009年   150篇
  2008年   172篇
  2007年   195篇
  2006年   186篇
  2005年   187篇
  2004年   153篇
  2003年   127篇
  2002年   137篇
  2001年   148篇
  2000年   129篇
  1999年   100篇
  1998年   40篇
  1997年   26篇
  1996年   33篇
  1995年   30篇
  1994年   21篇
  1993年   19篇
  1992年   54篇
  1991年   44篇
  1990年   39篇
  1989年   36篇
  1988年   46篇
  1987年   55篇
  1986年   52篇
  1985年   29篇
  1984年   20篇
  1983年   17篇
  1982年   13篇
  1981年   11篇
  1979年   15篇
  1978年   11篇
  1977年   10篇
  1976年   9篇
  1975年   6篇
  1973年   9篇
  1971年   7篇
排序方式: 共有3944条查询结果,搜索用时 15 毫秒
71.
BACKGROUND: AND OBJECTIVES: The mitochondrial DNA A to G mutation at nucleotide 3243 (mt3243) is associated with a subtype of diabetes characterized by maternal transmission and deafness. We have previously reported a 2.7% prevalence of this mutation in a cohort of young patients with either type 1 or type 2 diabetes. In this study, we aimed to confirm this finding by examining for the prevalence of this mutation in a large-scale study. SUBJECTS AND METHODS: Nine hundred and six unrelated Chinese patients with type 2 diabetes and 213 nondiabetic controls were studied. The presence of mt3243 mutation was determined by polymerase chain reaction amplification and ApaI digestion. RESULTS: This mutation was found in four of 133 (3.0%) patients with early onset ( 40 years) diabetes and no family history. Basal pancreatic beta-cell function, as assessed by fasting plasma C-peptide, was variable amongst mutation carriers, and did not correlate with the level of heteroplasmy of mutation. CONCLUSIONS: In agreement with most studies, our results suggest that despite the high prevalence of positive maternal family history of diabetes amongst our type 2 diabetic patients, mt3243 mutation was not a major cause of diabetes in either early- or late-onset diabetic patients in Hong Kong. The role of other genetic, environmental and intrauterine factors needs further investigation.  相似文献   
72.
Introduction: Challenges remain in predicting mortality and severe myocardial dysfunction in patients undergoing primary percutaneous coronary intervention (PPCI) for ST elevation myocardial infarction (STEMI).

Areas covered: Cardiogenic shock is associated with a high mortality rate. Less well characterized are patients who are not in cardiogenic shock but will die from pump failure as a result of a STEMI. There is a long history of using hemodynamics to risk stratify patients with acute MI with the Killip class being shown to provide prognostic information in the prereperfusion, thrombolytic and PPCI eras. Recent studies have identified low systolic blood pressure (SBP), elevated heart rate, elevated left ventricular end diastolic pressure (LVEDP), and low SBP/LVEDP ratio as hemodynamic parameters associated with early mortality in patients undergoing PPCI. Although infrequently used, prognostic information can be obtained from right heart catheterization in the setting of STEMI with the best-studied parameters being cardiac power, pulmonary capillary wedge pressure (PCWP), cardiac output, right atrial pressure/PCWP ratio, and pulmonary artery pulsatility index.

Expert commentary: Hemodynamic parameters measured at the time of PPCI provide important prognostic information. Whether hemodynamics can be used to determine which patients benefit from early initiation of mechanical support remains to be determined.  相似文献   

73.
74.

Background

Optimal management of urinary tract infections (UTIs) in the emergency department (ED) is challenging due to high patient turnover, decreased continuity of care, and treatment decisions made in the absence of microbiologic data. We sought to identify risk factors for return visits in ED patients treated for UTI.

Methods

A random sample of 350 adult ED patients with UTI by ICD 9/10 codes was selected for review. Relevant data was extracted from medical charts and compared between patients with and without ED return visits within 30 days (ERVs).

Results

We identified 51 patients (15%) with 59 ERVs, of whom 6% returned within 72 h. Nearly half of ERVs (47%) were UTI-related and 33% of ERV patients required hospitalization. ERVs were significantly more likely (P < 0.05) in patients with the following: age  65 years; pregnancy; skilled nursing facility residence; dementia; psychiatric disorder; obstructive uropathy; healthcare exposure; temperature  38 °C heart rate > 100; and bacteremia. Escherichia coli was the most common uropathogen (70%) and susceptibility rates to most oral antibiotics were below 80% in both groups except nitrofurantoin (99% susceptible).Cephalexin was the most frequently prescribed antibiotic (51% vs. 44%; P = 0.32). Cephalexin bug-drug mismatches were more common in ERV patients (41% vs. 15%; P = 0.02). Culture follow-up occurred less frequently in ERV patients (75% vs. 100%; P < 0.05).

Conclusions

ERV in UTI patients may be minimized by using ED-source specific antibiogram data to guide empiric treatment decisions and by targeting at-risk patients for post-discharge follow-up.  相似文献   
75.
PURPOSE: To examine the feasibility of a direct videoscopic approach to the descending thoracic aorta for endograft delivery to the aortic arch. METHODS: A double purse-string suture was placed on the aorta of 3 pigs via a thoracoscopic approach. Subsequently, the aorta was cannulated in the center of the purse-string. A 22-F delivery catheter was advanced under fluoroscopic control over a guidewire via a trocar into the proximal aorta. After deployment of a tubular endograft, the catheter was withdrawn from the aorta while simultaneously tightening the purse-string suture, without aortic cross clamping. The outcome was evaluated by post implant angiography and autopsy results. RESULTS: The procedure was successfully completed in all animals, with a mean total procedure time of 126 minutes (range 118-137). Mean endograft implantation time from needle puncture to catheter extraction was 27 minutes (range 21-37). Hemostasis was obtained in all animals after withdrawal of the delivery catheter and tightening the purse-string suture. The mean blood loss was 143 mL (range 80-220). Autopsy proved all purse-string sutures to be adequately placed and all endografts deployed in the correct position. CONCLUSION: A direct videoscopic approach to the descending thoracic aorta proved a feasible technique for endograft delivery to the aortic arch in a porcine model.  相似文献   
76.
77.
We report a case of progressive right coronary artery dissection complicating direct angioplasty for an acute inferior myocardial infarct, with successful bail-out stenting of the affected vessel.  相似文献   
78.
Summary A wide variety of diseases and injuries can cause granulomatous hepatitis, and drug-induced granulomatous hepatitis is a well-described entity. Sulfonylurea derivatives, which are commonly used oral hypoglycemic agents in the treatment of non-insulin-dependent diabetes mellitus, have been implicated in liver disease. However, glyburide, a second-generation sulfonylurea and a potent hypoglycemic drug, is considered to have less hepatic side effects than chlorpropamide. It has been reportedly associated with cholestatic jaundice and hepatitis and with hypersensitivity angiitis. A case of necrotizing granuloma has been reported. We present a second case of granulomatous hepatitis occurring in a patient who had been taking glyburide for approximately three years, and we review the literature for glyburide-associated hepatitis.  相似文献   
79.
Described here is a case of multiple myeloma in a patient with sickle cell anemia. Viscometric studies were made by comparing the patient's whole blood, plasma and washed red blood cells with those of a normal control subject and a patient with sickle cell anemia. Results showed that the increased viscosity of the patient's whole blood as compared with that of the control patient with sickle cell anemia was mainly due to erythrocytic Interaction with the circulating abnormal immunoglobulin. It is postulated that the increased frequency of vaso-occlusive crisis that occurred in our patient in the months before the diagnosis and treatment of multiple myeloma, was due to this cell-protein interaction with the resulting enhancement of whole blood viscosity and the sickling phenomena.  相似文献   
80.
The in vitro steroidogenic capacity of the gonadal tissue in the protandrous Rhabdosargus sarba was studied. Testicular and ovarian tissues from various sexual phases were used either separately or combined. With progesterone as precursor, high yield of 5 beta-reduced metabolites, and no 11-ketotestosterone or 11 beta-hydroxytestosterone were found. The production of 5 beta-pregnan-3 alpha-ol-20-one and 5 beta-pregnane-3,20-dione was very high in incubations with testicular tissue from intersexes or males and was low in those with ovarian tissue only. The production of 17 alpha-hydroxyprogesterone was high in the female but was low in other sexual phases. With testosterone as precursor, 11-ketotestoterone and 11 beta-hydroxytestosterone were identified. The latter was the most abundant and prominent polar steroid in all incubations. 5 beta-Reductase activity was high in the male and relatively low in the female. 5 alpha-Reduced products, however, were absent. There was an increase in the production of androstenedione as the animal underwent sex reversal. The significance of this change in steroidogenesis in this protandrous fish is at present under investigation. Experimental results also indicated that in the intersexual gonad there may be interaction between the testicular component and the ovarian component in steroidgenesis.  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