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   4737篇
  免费   256篇
  国内免费   10篇
耳鼻咽喉   26篇
儿科学   167篇
妇产科学   143篇
基础医学   546篇
口腔科学   51篇
临床医学   821篇
内科学   787篇
皮肤病学   81篇
神经病学   458篇
特种医学   76篇
外科学   470篇
综合类   38篇
一般理论   7篇
预防医学   671篇
眼科学   57篇
药学   243篇
中国医学   6篇
肿瘤学   355篇
  2024年   5篇
  2023年   27篇
  2022年   34篇
  2021年   72篇
  2020年   60篇
  2019年   103篇
  2018年   113篇
  2017年   92篇
  2016年   92篇
  2015年   108篇
  2014年   160篇
  2013年   258篇
  2012年   386篇
  2011年   370篇
  2010年   227篇
  2009年   184篇
  2008年   327篇
  2007年   360篇
  2006年   345篇
  2005年   326篇
  2004年   324篇
  2003年   310篇
  2002年   249篇
  2001年   36篇
  2000年   31篇
  1999年   31篇
  1998年   40篇
  1997年   38篇
  1996年   40篇
  1995年   36篇
  1994年   31篇
  1993年   37篇
  1992年   21篇
  1991年   13篇
  1990年   17篇
  1989年   10篇
  1988年   11篇
  1987年   11篇
  1986年   9篇
  1985年   7篇
  1984年   7篇
  1983年   7篇
  1982年   7篇
  1981年   13篇
  1980年   10篇
  1976年   2篇
  1975年   2篇
  1973年   1篇
  1972年   1篇
  1971年   1篇
排序方式: 共有5003条查询结果,搜索用时 0 毫秒
951.
BACKGROUND: Although colorectal cancer (CRC) is the third leading cause of cancer death among US women and is particularly deadly among African Americans, CRC screening rates remain low. Within a low-income population of women, the authors examined racial differences in practices, knowledge, and barriers related to CRC screening. METHODS: Face-to-face interviews were conducted with 941 women (white, n= 186; African American, n= 755) older than age 50 years who were living in subsidized housing communities in 11 cities in North and South Carolina. Women were asked questions about their CRC screening history and their knowledge and beliefs concerning CRC screening. RESULTS: Half (49%) of the women interviewed were within CRC screening guidelines, and this did not vary by race (P= .17). However, African American women were half as likely as white women to report having had a screening colonoscopy within the past 10 years (odds ratio [OR], 0.46; P< .001). Awareness of tests for CRC was low overall (39%) and was lower among African Americans than whites (OR, 0.44; P< .001). Compared with white women, African American women were less likely to report embarrassment as a barrier (OR, 0.59; P= .008) and more likely to report lack of insurance coverage (OR, 1.75; P= .098). CONCLUSIONS: Efforts must continue to increase women's knowledge of both CRC screening tests and colon cancer risk factors. Among these low-income women, routine encounters with the healthcare system may present opportunities to reduce deficits in CRC knowledge and to improve overall CRC screening rates.  相似文献   
952.
953.
954.
Lymphedema is a chronic and progressive long-term adverse effect of breast cancer treatment commonly defined by swelling of the affected arm. Current clinical guidelines indicate that women with and at risk for lymphedema should protect the affected arm from overuse. In clinical practice, this often translates into risk aversive guidance to avoid using the arm. This could lead to a disuse pattern that may increase the likelihood of injury from common activities of daily living. Further, such guidance poses an additional barrier to staying physically active, potentially translating to weight gain, which has been shown to be associated with worse clinical course for women with lymphedema. We hypothesize that a program of slowly progressive strength training with no upper limit on the amount of weight that may be lifted would gradually increase the physiologic capacity of the arm so that common activities represent a decreasing percentage of maximal capacity. Theoretically, this increased capacity should decrease the risk that daily activities put stress on the lymphatic system of the affected side. The Physical Activity and Lymphedema (PAL) Trial is a recently completed randomized controlled exercise intervention trial that recruited 295 breast cancer survivors (141 with lymphedema at study entry, 154 at risk for lymphedema at study entry). The purpose of this report is to provide detail regarding the study design, statistical design, and protocol of the PAL trial.  相似文献   
955.
956.
Pitch deviation analysis of pathological voice in connected speech   总被引:1,自引:0,他引:1  
OBJECTIVES: This study compares normal and pathologic voices using a novel voice analysis algorithm that examines pitch deviation during connected speech. The study evaluates the clinical potential of the algorithm as a mechanism to distinguish between normal and pathologic voices using connected speech. METHODS: Adult vocalizations from normal subjects and patients with known benign free-edge vocal fold lesions were analyzed. Recordings had been previously obtained in quiet under controlled conditions. Two phrases and sustained /a/ were recorded per subject. The subject populations consisted of 10 normal and 31 abnormal subjects. The voice analysis algorithm generated 2-dimensional patterns that represent pitch deviation in time and under variable window widths. Measures were collected from these patterns for window widths between 10 and 250 ms. For comparison, jitter and shimmer measures were collected from sustained /a/ by means of the Computerized Speech Lab (CSL). A t-test and tests of sensitivity and specificity assessed discrimination between normal and abnormal populations. RESULTS: More than 58% of the measures collected from connected speech outperformed the CSL jitter and shimmer measures in population discrimination. Twenty-five percent of the experimental measures (including /a/) indicated significantly different populations (p < .01%). CONCLUSIONS: The results demonstrate that the algorithm distinguishes between normal and abnormal populations by use of samples of connected speech.  相似文献   
957.
958.
959.
Background Idiopathic pulmonary arterial hypertension (IPAH) is a rare disease in children. By definition it is a diagnosis of exclusion, and CT of the chest is primarily performed to exclude other causes. Previous studies have defined CT features suggestive of the diagnosis of IPAH, but these have all been limited to the adult population. Objective Contrast-enhanced chest CT and high-resolution CT findings in IPAH were evaluated in an attempt to define features consistently seen in children with this condition. Materials and methods The chest CT scans performed at initial presentation were reviewed in 17 children with echocardiographic or angiographic evidence of IPAH. Result There were nine boys and eight girls, ranging in age from 1 month to 17 years. The extrapulmonary findings included cardiomegaly with right-sided cardiac enlargement, which was seen in 13 children. The central pulmonary arteries were enlarged in 15 children, with peripheral enlargement in two. In six children this resulted in bronchial compression. In addition, mediastinal and hilar lymphadenopathy was noted in three children. Prominent intrapulmonary features included a peripheral vasculopathy, with enlarged tortuous vessels, seen in eight children. Ill-defined ground-glass centrilobular opacities were also noted in eight children, representing the most common parenchymal abnormality. Other findings included septal lines in five, diffuse ground-glass opacification in four and focal hyperlucent zones in three. Mosaic attenuation was seen in one child. Conclusion A variety of imaging findings are identified in IPAH. Features particularly consistent with the diagnosis include peripheral vasculopathy and centrilobular opacities in the setting of cardiomegaly and central pulmonary arterial enlargement.  相似文献   
960.
Preservative sensitivity in the UK was last assessed in 2000. Given the changes in preservative usage, we have re-evaluated our patch test data in order to detect any changes in the trend of sensitization. The results of patch testing using the extended British Contact Dermatitis Society Standard series were collected from 9 dermatology centres in the UK. Positive reactions to each of 10 preservative allergens were captured together with the MOAHFLA indices for each centre. In total, 6958 patients were tested during the period 2004-2005. The current data were compared with previously published data. Formaldehyde and methylchloroisothiazolinone/methyl-isothiazolinone have the highest positivity rates at 2.0% and chloroxylenol the lowest at 0.2%. Parabens mix has the highest irritancy rate. Compared with the UK data in 2000, the positivity rate of imidazolidinyl urea (0.02 < P < 0.05) has significantly increased and that of methyldibromo glutaronitrile has significantly reduced (P < 0.001).  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