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   3636篇
  免费   208篇
  国内免费   5篇
耳鼻咽喉   16篇
儿科学   92篇
妇产科学   90篇
基础医学   384篇
口腔科学   52篇
临床医学   505篇
内科学   539篇
皮肤病学   76篇
神经病学   262篇
特种医学   93篇
外科学   500篇
综合类   49篇
一般理论   4篇
预防医学   546篇
眼科学   134篇
药学   278篇
中国医学   3篇
肿瘤学   226篇
  2023年   33篇
  2022年   55篇
  2021年   93篇
  2020年   50篇
  2019年   91篇
  2018年   85篇
  2017年   78篇
  2016年   79篇
  2015年   93篇
  2014年   128篇
  2013年   170篇
  2012年   286篇
  2011年   295篇
  2010年   156篇
  2009年   120篇
  2008年   224篇
  2007年   230篇
  2006年   228篇
  2005年   235篇
  2004年   202篇
  2003年   192篇
  2002年   157篇
  2001年   45篇
  2000年   39篇
  1999年   37篇
  1998年   31篇
  1997年   24篇
  1996年   23篇
  1995年   24篇
  1994年   17篇
  1993年   11篇
  1992年   25篇
  1991年   33篇
  1990年   27篇
  1989年   20篇
  1988年   14篇
  1987年   17篇
  1986年   18篇
  1985年   13篇
  1984年   16篇
  1983年   12篇
  1980年   10篇
  1979年   8篇
  1976年   7篇
  1975年   7篇
  1974年   7篇
  1973年   10篇
  1972年   7篇
  1971年   12篇
  1970年   8篇
排序方式: 共有3849条查询结果,搜索用时 15 毫秒
61.

Purpose

To investigate whether intravitreal ranibizumab injections administered to a child alter systemic plasma levels of total and free VEGF 165.

Methods

A 9-year-old child sustained a choroidal rupture from blunt trauma. He subsequently developed a secondary choroidal neovascular membrane, which was treated with five ranibizumab injections over a period of 8 months. Peripheral venous blood samples were taken at each visit over a period of 12 months and plasma was extracted. Plasma VEGF 165 levels were determined using enzyme-linked immunosorbent assay and were assayed both pre- and post-immunodepletion to remove complexed VEGF.

Results

Plasma VEGF 165 levels proved labile following intravitreal injection of ranibizumab. Levels increased by 30% above baseline following the first intravitreal ranibizumab injection, but then returned to baseline despite two subsequent injections. There was then a rebound increase of 67% in total plasma VEGF levels following a further injection, which remained above baseline for 12 weeks despite two further intravitreal ranibizumab injections. Baseline levels were re-attained 26 weeks after the final injection.

Conclusions

These results suggest intravitreal ranibizumab injections can cause significant, multiphasic changes in systemic VEGF levels. This may be of particular clinical significance in children as VEGF is known to be vital in the development of major organs, in addition to its role in the maintenance of normal organ function in adults.  相似文献   
62.

Background

Diabetic retinopathy is one of the most common complications of diabetes. The screening of patients with diabetes to detect retinopathy is recommended by several professional guidelines but is an underutilized service.

Objective

To analyze the relationship between the frequency of retinopathy screening and the cost of care in adult patients with diabetes.

Methods

Truven Health MarketScan commercial databases (2000–2013) were used to identify the diabetic population aged 18 to 64 years for the performance of a 2001–2013 annual trend analysis of patients with type 1 and type 2 diabetes and a 10-year longitudinal analysis of patients with newly diagnosed type 2 diabetes. In the trend analysis, the prevalence of diabetes, screening rate, and allowed cost per member per month (PMPM) were calculated. In the longitudinal analysis, data from 4 index years (2001–2004) of patients newly diagnosed with type 2 diabetes were combined, and the costs were adjusted to be comparable to the 2004 index year cohort, using the annual diabetes population cost trends calculated in the trend analysis. The longitudinal population was segmented into the number of years of diabetic retinopathy screening (ie, 0, 1–4, 5–7, and 8–10), and the relationship between the years of screening and the PMPM allowed costs was analyzed. The difference in mean incremental cost between years 1 and 10 in each of the 4 cohorts was compared after adjusting for explanatory variables.

Results

In the trend analysis, between 2001 and 2013, the prevalence of diabetes increased from 3.93% to 5.08%, retinal screening increased from 26.27% to 29.58%, and the average total unadjusted allowed cost of care for each patient with diabetes increased from $822 to $1395 PMPM. In the longitudinal analysis, the difference between the screening cohorts’ mean incremental cost increase was $185 between the 0- and 1–4–year cohorts (P <.003) and $202 between the 0- and 5–7–year cohorts (P <.023). The cost differences between the other cohorts, including $217 between the 0- and 8–10–year cohorts (P <.066), were not statistically significant.

Conclusions

Based on our analysis, the annual retinopathy screening rate for patients with diabetes has remained low since 2001, and has been well below the guideline-recommended screening levels. For patients with type 2 diabetes, the mean increase in healthcare expenditures over a 10-year period after diagnosis is not statistically different among those with various retinopathy screening rates, although the increase in healthcare spending is lower for patients with diabetes who were not screened for retinopathy compared with patients who did get screened.  相似文献   
63.
Fixed dose combination (FDC) dual bronchodilators that co-administer a long acting β2-adrenoceptor agonist (LABA) and a long acting muscarinic antagonist (LAMA) are a new class of inhaled treatment for chronic obstructive pulmonary disease (COPD). This review focuses on the clinical evidence for the benefit of LABA/LAMA FDCs compared with monocomponent treatments, and also compared with active comparators that are widely used for the treatment of COPD, namely tiotropium and salmeterol-fluticasone. Novel FDC dual bronchodilators include QVA149 and umeclidinium/vilanterol (UMEC/VI). Long term clinical trials show that QVA149 and UMEC/VI are superior to monocomponent therapy in terms of trough forced expiratory volume in 1 s (FEV1), although the FEV1 improvement was limited to approximately 80–90% of the added monocomponent values. This suggests that the effect of combining a LABA and a LAMA is not fully additive. LABA/LAMA FDC were associated with the largest mean changes in symptoms and health status that were above the minimal clinically important difference, in contrast to the monocomponents. Furthermore, these LABA/LAMA FDCs demonstrated superiority over the active comparators tiotropium and salmeterol-fluticasone in terms of trough FEV1 and patient-reported outcomes. LABA/LAMA FDCs offer a simplified means of maximizing bronchodilation for COPD patients, with the improvements in lung function being mirrored by benefits in terms of symptoms and exacerbations. The use of LABA/LAMA FDCs in clinical practice is set to grow and further studies are needed to define their optimal place in treatment guidelines.  相似文献   
64.
The mortality rate in spontaneous bacterial peritonitis is reportedly high. Patients rarely survive the initial infection. Most patients die either because of infection or end-stage liver disease. A patient with alcoholic cirrhosis and portal hypertension with five distinct episodes of spontaneous bacterial peritonitis over a 2 1/2-year period is described.  相似文献   
65.
The objectives of this study were to examine relationships between baseline levels of reproductive hormones in older men and (1) change in bone mineral density (BMD) over 5 years and (2) incident fractures over an average of 6 years' follow‐up. A total of 1705 men aged 70 years and older from the Concord Health and Ageing in Men Project (CHAMP) study were assessed at baseline (2005–2007), 2 years follow‐up (2007–2009), and 5 years follow‐up (2010–2013). At baseline, testosterone (T), dihydrotestosterone (DHT), estradiol (E2), and estrone (E1) were measured by liquid chromatography–tandem mass spectrometry (LC‐MS/MS), and sex hormone–binding globulin (SHBG), luteinizing hormone (LH), and follicle‐stimulating hormone (FSH) by immunoassay. Hip BMD was measured by dual X‐ray absorptiometry (DXA) at all three time‐points. Fracture data were collected at 4‐monthly phone calls and verified radiographically. Statistical modeling was by general estimating equations and Cox model regression. Univariate analyses revealed inverse associations for serum SHBG, FSH, and LH and positive association for E1 but not DHT or E2 with BMD loss at the hip across the three time points. Serum levels of SHBG (β = –0.071), FSH (β = –0.085), LH (β = –0.070), and E1 (β = 0.107) remained significantly associated with BMD loss in multivariate‐adjusted models; however, we were unable to identify any thresholds for accelerated BMD loss according to reproductive steroids. Incident fractures (all, n = 171; hip, n = 44; and nonvertebral, n = 139) were all significantly associated with serum SHBG, FSH, and LH levels in univariate models but none remained significantly associated in multivariate‐adjusted model. Serum T, DHT, E2, and E1 levels were not associated with incident fractures in univariate or multivariate‐adjusted analyses. In older men, lower serum SHBG, FSH, and LH and higher E1 levels protected against loss of BMD without increasing fracture rate. This means these reproductive variables may be considered as novel biomarkers of bone health during male aging. © 2015 American Society for Bone and Mineral Research.  相似文献   
66.
Previously reported cases of botulism in infants have been diagnosed as infant botulism; that is, botulism caused by intestinal colonization by Clostridium botulinum with intraluminal production and absorption of toxin. Foodborne botulism is caused by ingestion of preformed toxin. We describe an unusual case of foodborne botulism in a 6-month-old infant caused by the ingestion of improperly prepared home-canned baby food. This represents the youngest age of onset for foodborne botulism in the United States of which we are aware and illustrates the need to rule out foodborne botulism, which represents a public health emergency, regardless of the patient's age. The diagnosis could have been readily missed or delayed in this case because the weakness was rapidly progressive rather than insidious, as is typical of infant botulism.  相似文献   
67.
68.

Background

Early identification and entry into care is critical to reducing morbidity and mortality in children with HIV. The objective of this report is to describe the impact of the Tingathe programme, which utilizes community health workers (CHWs) to improve identification and enrolment into care of HIV-exposed and -infected infants and children.

Methods

Three programme phases are described. During the first phase, Mentorship Only (MO) (March 2007–February 2008) on-site clinical mentorship on paediatric HIV care was provided. In the second phase, Tingathe-Basic (March 2008–February 2009), CHWs provided HIV testing and counselling to improve case finding of HIV-exposed and -infected children. In the final phase, Tingathe-PMTCT (prevention of mother-to-child transmission) (March 2009–February 2011), CHWs were also assigned to HIV-positive pregnant women to improve mother-infant retention in care. We reviewed routinely collected programme data from HIV testing registers, patient mastercards and clinic attendance registers from March 2005 to March 2011.

Results

During MO, 42 children (38 HIV-infected and 4 HIV-exposed) were active in care. During Tingathe-Basic, 238 HIV-infected children (HIC) were newly enrolled, a six-fold increase in rate of enrolment from 3.2 to 19.8 per month. The number of HIV-exposed infants (HEI) increased from 4 to 118. During Tingathe-PMTCT, 526 HIC were newly enrolled over 24 months, at a rate of 21.9 patients per month. There was also a seven-fold increase in the average number of exposed infants enrolled per month (9.5–70 patients per month), resulting in 1667 enrolled with a younger median age at enrolment (5.2 vs. 2.5 months; p<0.001).During the Tingathe-Basic and Tingathe-PMTCT periods, CHWs conducted 44,388 rapid HIV tests, 7658 (17.3%) in children aged 18 months to 15 years; 351 (4.6%) tested HIV-positive. Over this time, 1781 HEI were enrolled, with 102 (5.7%) found HIV-infected by positive PCR. Additional HIC entered care through various mechanisms (including positive linkage by CHWs and transfer-ins) such that by February 2011, a total of 866 HIC were receiving care, a 23-fold increase from 2008.

Conclusions

A multipronged approach utilizing CHWs to conduct HIV testing, link HIC into care and provide support to PMTCT mothers can dramatically improve the identification and enrolment into care of HIV-exposed and -infected children.  相似文献   
69.

Background

Dialysis-requiring acute kidney injury (D-AKI) is a serious complication in hospitalized heart failure (HF) patients. However, data on national trends are lacking after 2002.

Methods

We used the Nationwide Inpatient Sample (2002–2013) to identify HF hospitalizations with and without D-AKI. We analyzed trends in incidence, in-hospital mortality, length of stay (LoS), and cost. We calculated adjusted odds ratios (aORs) for predictors of D-AKI and for outcomes including in-hospital mortality and adverse discharge (discharge to skilled nursing facilities, nursing homes, etc).

Results

We identified 11,205,743 HF hospitalizations. Across 2002–2013, the incidence of D-AKI doubled from 0.51% to 1.09%. We found male sex, younger age, African-American and Hispanic race, and various comorbidities and procedures, such as sepsis and mechanical ventilation, to be independent predictors of D-AKI in HF hospitalizations. D-AKI was associated with higher odds of in-hospital mortality (aOR 2.49, 95% confidence interval [CI] 2.36–2.63; P?<?.01) and adverse discharge (aOR 2.04, 95% CI 1.95–2.13; P?<?.01). In-hospital mortality and attributable risk of mortality due to D-AKI decreased across 2002–2013. LoS and cost also decreased across this period.

Conclusions

The incidence of D-AKI in HF hospitalizations doubled across 2002–2013. Despite declining in-hospital mortality, LoS, and cost, D-AKI was associated with worse outcomes.  相似文献   
70.
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