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   1140篇
  免费   81篇
  国内免费   5篇
耳鼻咽喉   21篇
儿科学   44篇
妇产科学   5篇
基础医学   103篇
口腔科学   37篇
临床医学   110篇
内科学   261篇
皮肤病学   7篇
神经病学   77篇
特种医学   41篇
外科学   233篇
综合类   15篇
一般理论   1篇
预防医学   54篇
眼科学   31篇
药学   100篇
中国医学   2篇
肿瘤学   84篇
  2024年   3篇
  2023年   16篇
  2022年   50篇
  2021年   100篇
  2020年   61篇
  2019年   62篇
  2018年   66篇
  2017年   43篇
  2016年   47篇
  2015年   46篇
  2014年   69篇
  2013年   69篇
  2012年   112篇
  2011年   96篇
  2010年   51篇
  2009年   37篇
  2008年   56篇
  2007年   55篇
  2006年   53篇
  2005年   39篇
  2004年   29篇
  2003年   21篇
  2002年   17篇
  2001年   4篇
  2000年   5篇
  1999年   5篇
  1998年   4篇
  1997年   2篇
  1992年   2篇
  1990年   4篇
  1989年   1篇
  1984年   1篇
排序方式: 共有1226条查询结果,搜索用时 62 毫秒
101.
Current advancements in imaging technology, especially three-dimensional/four-dimensional ultrasound and contrast-enhanced imaging, have increased the diagnostic yield of adnexal masses. The benefit of ultrasound is the characterization of an adnexal mass, suggesting the probable etiology of the mass. Masses may be divided as solid, cystic, or complex. It is predominantly the solid and complex masses that need a thorough evaluation. The role of color-flow imaging is now gaining importance and criteria for distinguishing between benign and malignant masses are often possible. Availability of a scoring system enables the differentiation of small adnexal masses. Several benign lesions may present as complex masses but can be distinguished and diagnosed on sonography. The availability of 3D ultrasound has been of great use to understand spatial relations and vascular morphology. Sonography allows a more detailed assessment of morphologic features of an adnexal mass. With a benign-appearing adnexal mass on sonography, the need for any further diagnostic tests is often obviated.  相似文献   
102.
ABSTRACT

Introduction

The globally rampant SARS CoV-2 pandemic requires novel medical strategies to control the severity of disease and death due to complications. Of the 15–20% patients that develop pulmonary symptoms, a sub-set develops an acute respiratory distress syndrome (ARDS) rapidly progressing into a critical condition. Marked elevation of cytokines/chemokines is observed with elevation of additional markers of inflammation, coagulation, and organ damage such as CRP, D-dimer, LDH, Ferritin and Troponin-I. This hyperinflammation leads to worsening of oxygen saturation due to pulmonary infiltration and exudation, organ damage, and dysfunction of coagulation pathway and may lead to multi-organ failure.  相似文献   
103.
104.
105.
The purpose of the present study was to assess the effect of crude extracts of marine actinobacteria on larvicidal, repellent, and ovicidal activities against Culex tritaeniorhynchus and Culex gelidus (Diptera: Culicidae). The early fourth instar larvae of C. tritaeniorhynchus and C. gelidus, reared in the laboratory, were used for larvicidal, ovicidal, and repellent assay with crude extracts of actinobacteria. Saccharomonospora spp. (LK-1), Streptomyces roseiscleroticus (LK-2), and Streptomyces gedanensis (LK-3) were identified as potential biocide producers. Based on the antimicrobial activity, three strains were chosen for larvicidal activity. The marine actinobacterial extracts showed moderate to high larvicidal effects after 24 h of exposure at 1,000 ppm and the highest larval mortality was found in extract of LK-3 (LC50 = 108.08 ppm and LC90 = 609.15 ppm) against the larvae of C. gelidus and (LC50 = 146.24 ppm and LC90 = 762.69 ppm) against the larvae of C. tritaeniorhynchus. Complete protections for 240 min were found in crude extract of LK-2 and LK-3 at 1,000 ppm, against mosquito bites of C. tritaeniorhynchus and C. gelidus, respectively. After 24-h treatment, mean percent hatchability of the ovicidal activity was observed. The percent hatchability was inversely proportional to the concentration of extract and directly proportional to the eggs. Crude extracts of LK-1 and LK-3 showed no hatchability at 1,000 ppm against C. tritaeniorhynchus and C. gelidus, respectively. This is an ideal ecofriendly approach for the control of Japanese encephalitis vectors, C. tritaeniorhynchus and C. gelidus.  相似文献   
106.
Prior transcranial magnetic stimulation studies showed that resting motor threshold is elevated in abstinent cocaine-dependent patients, suggesting a decrease in axonal excitability. In contrast, the increased incidence of seizures and psychosis in this group suggests increased excitability or decreased inhibition. Here, we studied long-interval intracortical facilitation and long-interval intracortical inhibition, paired-pulse transcranial magnetic stimulation measures that are more directly linked to glutamatergic cortical facilitation and GABAergic inhibition, respectively. Ten cocaine-dependent and 10 healthy controls were examined. Resting motor threshold, long-interval intracortical facilitation and long-interval intracortical inhibition were tested from the left motor cortex. The cocaine group showed an elevated resting motor threshold and an increased long-interval intracortical facilitation, whereas long-interval intracortical inhibition was normal. Although the increase in long-interval intracortical facilitation suggests exaggerated cortical glutamatergic excitability, the increase in resting motor threshold may signify a protective mechanism against seizures and psychosis.  相似文献   
107.
Primary biliary cirrhosis (PBC) is a chronic cholestatic liver disorder that can progress to cirrhosis, shortening life expectancy. PBC patients are often asymptomatic, present with biochemical cholestasis, and test positive (>or=90%) for antimitochondrial antibodies (AMAs) in serum. Although AMA positivity without biochemical cholestasis may indicate increased risk of future PBC development, the contribution of these antibodies to pathogenesis remains enigmatic. Environmental risks and genetic determinants are likely implicated in PBC etiology. Given the familial aggregation of PBC, we hypothesized that AMAs also aggregate among relatives of PBC probands. We investigated the prevalence of AMAs in first-degree relatives (FDRs) of PBC probands to examine whether AMAs aggregate in such pedigrees. Using a PBC family registry, we prospectively screened for AMAs in the serum of 306 FDRs in 145 pedigrees, 350 PBC probands, and 196 controls who were age-matched, sex-matched, race-matched, and residence-matched to probands. The prevalence of AMA in FDRs and controls was 13.1% and 1%, respectively. Greater prevalence of AMA was found in female FDRs of PBC probands [sisters (20.7%), mothers (15.1%), and daughters (9.8%)] than in male FDRs [brothers (7.8%), fathers (3.7%), and sons (0%)]. CONCLUSIONS: AMAs aggregate among FDRs of PBC probands. Our data have clinical implications for FDRs of PBC probands because AMA positivity may suggest susceptibility to PBC. Thus, the identification and follow-up of these relatives may lead to earlier disease diagnosis and treatment. Furthermore, if AMA development is heritable, this trait will provide a basis to dissect the genetic predisposition to PBC.  相似文献   
108.
Hospitalization for diabetic ketoacidosis (DKA) is increasing, perhaps due to the rising incidence of DKA in patients with type 2 diabetes mellitus (T2DM). Ethnic minority groups are at increased risk for T2DM. This study aimed at elucidating the characteristics of patients with ketosis-prone diabetes in a predominantly ethnic minority population. We performed a retrospective analysis of adults admitted with DKA at the Bronx Lebanon Hospital Center, Bronx, NY over 3 years. The patients were divided into cohorts based on type of diabetes and ethnicity. The cohorts were described and compared using statistical methods. We recorded 219 cases of DKA in 168 patients, 97% of whom were African American or Hispanic. Fifty-three (32%) patients had T2DM. New-onset diabetes, which was more common in T2DM (P < .0001), and African Americans (P = .008), occurred in 42 patients (25%). Readmission with DKA was more common in the Hispanic patients with type 1 diabetes mellitus (T1DM) (P = .0001). Type 2 diabetes mellitus was more prevalent in the African Americans (P = .04). Patients with T1DM had more severe acidosis than patients with T2DM (lower pH and bicarbonate and larger anion gap; P = .03, .02, and .005, respectively). Creatinine level was higher in patients with T2DM (P = .04) who were also less likely to have identifiable precipitating causes (P = .02). Hemoglobin A(1c) level was higher in patients with new-onset diabetes (P < .05), but did not differ between those with T1DM and T2DM. Mortality, which was 2%, occurred only in the African Americans with T2DM. We conclude that DKA is an important mode of initial presentation of T2DM, with new-onset T2DM accounting for about 60% of all new cases of DKA. African American patients with T2DM, in comparison with the Hispanic patients, are more susceptible to developing DKA. Diabetic ketoacidosis could occur in T2DM without any identifiable precipitant. The rising incidence of DKA may be attributable to its increasing occurrence in T2DM; therefore, measures aimed at primary prevention of T2DM are worthwhile.  相似文献   
109.
110.
Rural-dwelling older adults experience unique challenges related to accessing medical and social services. This article describes the development, implementation, and experience of a novel, community-based program to identify rural-dwelling older adults with unmet medical and social needs that leveraged the existing emergency medical services (EMS) system. The program specifically included geriatrics training for EMS providers; screening of older adult EMS patients for falls, depression, and medication management strategies by EMS providers; communication of EMS findings to community-based case managers; in-home evaluation by case managers; and referral to community resources for medical and social interventions. Measures used to evaluate the program included patient needs identified by EMS or the in-home assessment, referrals provided to patients, and patient satisfaction. EMS screened 1,231 of 1,444 visits to older patients (85%). Of those receiving specific screens, 45% had fall-related, 69% medication management-related, and 20% depression-related needs identified. One hundred and seventy-one eligible EMS patients who could be contacted accepted the in-home assessment. Of the 153 individuals completing the assessment, 91% had identified needs and received referrals or interventions. This project demonstrated that screening by EMS during emergency care for common geriatric syndromes and linkage to case managers is feasible in this rural community, although many will refuse the services. Further patient evaluations by case managers, with subsequent interventions by existing service providers as required, can facilitate the needed linkages between vulnerable rural-dwelling older adults and needed community-based social and medical services.  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