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   4328篇
  免费   423篇
  国内免费   12篇
耳鼻咽喉   31篇
儿科学   88篇
妇产科学   109篇
基础医学   504篇
口腔科学   70篇
临床医学   421篇
内科学   850篇
皮肤病学   44篇
神经病学   235篇
特种医学   122篇
外科学   666篇
综合类   133篇
预防医学   443篇
眼科学   185篇
药学   312篇
中国医学   96篇
肿瘤学   454篇
  2023年   43篇
  2022年   57篇
  2021年   93篇
  2020年   64篇
  2019年   109篇
  2018年   96篇
  2017年   87篇
  2016年   85篇
  2015年   124篇
  2014年   147篇
  2013年   181篇
  2012年   267篇
  2011年   264篇
  2010年   170篇
  2009年   160篇
  2008年   262篇
  2007年   255篇
  2006年   228篇
  2005年   253篇
  2004年   201篇
  2003年   204篇
  2002年   160篇
  2001年   112篇
  2000年   115篇
  1999年   113篇
  1998年   44篇
  1997年   33篇
  1996年   27篇
  1995年   22篇
  1994年   30篇
  1993年   21篇
  1992年   86篇
  1991年   72篇
  1990年   64篇
  1989年   50篇
  1988年   62篇
  1987年   60篇
  1986年   45篇
  1985年   40篇
  1984年   25篇
  1983年   26篇
  1982年   27篇
  1981年   17篇
  1980年   10篇
  1979年   18篇
  1978年   15篇
  1976年   17篇
  1974年   12篇
  1972年   12篇
  1970年   11篇
排序方式: 共有4763条查询结果,搜索用时 15 毫秒
941.
Abstract: Background: An understanding of patterns of breastfeeding is necessary for the effective implementation of breastfeeding promotion and intervention programs. In Hong Kong, little current data have been gathered on women's breastfeeding rates. The objective of this study was to determine how patterns of breastfeeding, maternal demographics, and maternal employment affect continuation of breastfeeding in primiparous women in Hong Kong. Method: A longitudinal self‐report survey was used to collect data when first‐time mothers (n = 218) were in the hospital, at 1, 3, 6, 9, and 12 months postpartum, or until they weaned their infant. All data (self‐report survey, demographic data, and follow‐up telephone surveys) were collected in Cantonese and then translated into English. Data were analyzed by determining, first, the influence of individual variables on the length of breastfeeding using a simple Cox regression analysis, and second, by grouping variables according to time sequence and entering them into a Cox regression model in 4 sequential phases. Results: Factors that were significantly associated with continuation of breastfeeding were maternal age (HR = 0.97; p = 0.048); attendance at a prenatal breastfeeding class (HR = 0.69; p = 0.020); intended weeks of breastfeeding (HR = 0.97; p < 0.001); breastfeeding score in hospital (HR = 0.99; p = 0.009); and length of exclusive breastfeeding (HR = 0.93; p < 0.001). Similar results were obtained in the multiphase Cox regression analysis; only the breastfeeding score in hospital became marginally insignificant (p = 0.053) after adjusting for demographics, prenatal, and other immediate postpartum factors. Conclusions: Short periods of exclusive breastfeeding and early supplementation were common in this sample. Unlike previous research, maternal employment was not a statistically significant factor in length of continued breastfeeding. Study findings show that multiple factors influence continued breastfeeding in Hong Kong, suggesting further areas for investigation. Changes in practice may improve continued and exclusive breastfeeding rates. (BIRTH 30:3 September 2003)  相似文献   
942.
Zinc-deficient rats that had received a single dose of N-methyl-N-nitrosourea (MNU) intragastrically developed malignant lymphomas involving the liver, spleen, lung and kidney, as well as the usual epithelial tumours at the site of administration. Interestingly, the incidence of squamous-cell carcinoma of the pharynx was significantly higher in zinc-deficient rats than in control animals. Since MNU does not require metabolic activation, the development of the malignant lymphomas might be related to the generally depressed immunological state of zinc-deficient rats.  相似文献   
943.
A direct teratogenic effect of antiepileptic drugs (AEDs) on the fetus has been postulated. However, there may also be a primary effect of AEDs on placenta, with secondary consequences to the fetus. Thirteen carefully medically controlled epileptic women were followed prenatally and perinatally. Placentas from all were investigated morphologically and in two with electronmicroscopy. In nine patients, the placentas were studied with respect to insulin and insulin-like growth factor (IGF-I and IGF-II) receptor activity. In this pilot study of a group of carefully medically controlled epileptic women with low levels of AEDs, the results did not differ from normal controls. The possibility of adverse effects of higher concentrations of AEDs cannot be excluded, however.  相似文献   
944.
945.
946.

Background and aim

Despite a growing body of evidence from Western populations on the health benefits of Dietary Approaches to Stop Hypertension (DASH) diets, their applicability in South East Asian settings is not clear. We examined cross-sectional associations between DASH diet and cardio-metabolic risk factors among 1837 Malaysian and 2898 Philippines participants in a multi-national cohort.

Methods and results

Blood pressures, fasting lipid profile and fasting glucose were measured, and DASH score was computed based on a 22-item food frequency questionnaire. Older individuals, women, those not consuming alcohol and those undertaking regular physical activity were more likely to have higher DASH scores. In the Malaysian cohort, while total DASH score was not significantly associated with cardio-metabolic risk factors after adjusting for confounders, significant associations were observed for intake of green vegetable [0.011, standard error (SE): 0.004], and red and processed meat (?0.009, SE: 0.004) with total cholesterol. In the Philippines cohort, a 5-unit increase in total DASH score was significantly and inversely associated with systolic blood pressure (?1.41, SE: 0.40), diastolic blood pressure (?1.09, SE: 0.28), total cholesterol (?0.015, SE: 0.005), low-density lipoprotein cholesterol (?0.025, SE: 0.008), and triglyceride (?0.034, SE: 0.012) after adjusting for socio-demographic and lifestyle groups. Intake of milk and dairy products, red and processed meat, and sugared drinks were found to significantly associated with most risk factors.

Conclusions

Differential associations of DASH diet and dietary components with cardio-metabolic risk factors by country suggest the need for country-specific tailoring of dietary interventions to improve cardio-metabolic risk profiles.  相似文献   
947.
To access temporal changes in psychobehavioral responses to the coronavirus disease (COVID-19) pandemic, we conducted a 5-round (R1–R5) longitudinal population-based online survey in Hong Kong during January–September 2020. Most respondents reported wearing masks (R1 99.0% to R5 99.8%) and performing hand hygiene (R1 95.8% to R5 97.7%). Perceived COVID-19 severity decreased significantly, from 97.4% (R1) to 77.2% (R5), but perceived self-susceptibility remained high (87.2%–92.8%). Female sex and anxiety were associated with greater adoption of social distancing. Intention to receive COVID-19 vaccines decreased significantly (R4 48.7% to R5 37.6%). Greater anxiety, confidence in vaccine, and collective responsibility and weaker complacency were associated with higher tendency to receive COVID-19 vaccines. Although its generalizability should be assumed with caution, this study helps to formulate health communication strategies and foretells the initial low uptake rate of COVID-19 vaccines, suggesting that social distancing should be maintained in the medium term.  相似文献   
948.
949.
Annals of Surgical Oncology - Healthcare policies have focused on centralizing care to high-volume centers in an effort to optimize patient outcomes; however, little is known about patients’...  相似文献   
950.

Purpose

Our case series aims to study the growing use of FDG PET/CT in diagnostic evaluation and follow up of IgG4-RD with emphasis on patients presenting with coronary artery involvement.

Methods

We conducted a search on the nuclear medicine and rheumatology service databases and identified patients with histologically proven IgG4-RD with FDG PET/CT performed at the Singapore General Hospital. The radiological, clinical, and laboratory findings of these patients were analyzed retrospectively.

Results

The series included ten male and two female patients. The commonest organ involved (five patients) was the pancreas. In three patients, coronary artery involvement manifested as soft tissue masses surrounding the arterial lumens. In these patients, histological diagnosis was established from alternative biopsy sites with abnormal metabolic activity on FDG PET/CT.Correlation between laboratory and metabolic imaging findings was not statistically significant in our series.Four patients had follow-up FDG PET/CT; three showed interval reduction in metabolic activity to baseline. One showed persistent abnormal metabolic activity before a rise in IgG4 levels. The metabolic imaging response was used to guide steroid dose.

Conclusions

FDG PET/CT is a useful tool in evaluation and follow-up of IgG4-RD, particularly in identifying alternative biopsy sites in patients who present with coronary artery involvement. Hypermetabolic coronary artery masses on FDG PET/CT should raise clinical suspicion of IgG4-RD. As the coronary artery masses may not show decrease in size after treatment, FDG PET/CT is also useful for metabolic response assessment.
  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