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   1275篇
  免费   186篇
  国内免费   18篇
耳鼻咽喉   20篇
儿科学   55篇
妇产科学   22篇
基础医学   81篇
口腔科学   38篇
临床医学   206篇
内科学   273篇
皮肤病学   104篇
神经病学   39篇
特种医学   132篇
外科学   201篇
综合类   94篇
现状与发展   30篇
预防医学   61篇
眼科学   15篇
药学   34篇
中国医学   4篇
肿瘤学   70篇
  2024年   18篇
  2023年   179篇
  2022年   12篇
  2021年   16篇
  2020年   55篇
  2019年   21篇
  2018年   51篇
  2017年   45篇
  2016年   39篇
  2015年   57篇
  2014年   85篇
  2013年   63篇
  2012年   30篇
  2011年   30篇
  2010年   76篇
  2009年   88篇
  2008年   30篇
  2007年   51篇
  2006年   18篇
  2005年   17篇
  2004年   11篇
  2003年   19篇
  2002年   17篇
  2001年   11篇
  2000年   13篇
  1999年   28篇
  1998年   36篇
  1997年   49篇
  1996年   40篇
  1995年   35篇
  1994年   29篇
  1993年   34篇
  1992年   8篇
  1991年   8篇
  1990年   9篇
  1989年   22篇
  1988年   21篇
  1987年   14篇
  1986年   5篇
  1985年   12篇
  1984年   4篇
  1983年   3篇
  1982年   8篇
  1981年   10篇
  1980年   12篇
  1978年   5篇
  1977年   3篇
  1976年   13篇
  1975年   10篇
  1974年   3篇
排序方式: 共有1479条查询结果,搜索用时 15 毫秒
991.
992.
993.
Anomalous origin of one pulmonary artery from the aorta (AOPA) is a rare congenital anomaly. Here, we report the case of a premature infant with a delayed diagnosis of AOPA who died before surgical repair could be attempted, and we review the literature regarding the diagnosis and surgical approaches in premature infants with AOPA. © 2013 Wiley Periodicals, Inc. J Clin Ultrasound 42 :367–370, 2014  相似文献   
994.
995.
Background Human nail clippings are increasingly used in epidemiological studies as biomarkers for assessing diet and environmental exposure to trace elements or other chemical compounds. However, little is known about the growth rate of human nails. Objective To estimate the average growth rate of fingernails and toenails and examine factors that may influence nail growth rate. Methods Twenty‐two healthy American young adults marked their nails close to the proximal nail fold with a provided nail file following a standardized protocol, and recorded the date and the distance from the proximal nail fold to the mark. One to three months later, participants recorded the date and distance from the proximal nail fold to the mark again. Nail growth rate was calculated based on recorded distance and time between the two measurements. Results Average fingernail growth rate was faster than that of toenails (3.47 vs. 1.62 mm/month, P < 0.01). There was no significant difference between right and left fingernail/toenail growth rates. The little fingernail grew slower than other fingernails (P < 0.01); the great toenail grew faster than other toenails (P < 0.01). Younger age, male gender, and onychophagia were associated with faster nail growth rate; however, the differences were not statistically significant. Conclusion Nail growth rates have increased compared with previous estimates conducted decades ago. Toenail clippings may reflect a long exposure time frame given the relatively slow growth rate.  相似文献   
996.
997.
The correct choice of cosmetic products and cleansers is very important to improve skin hydration, to provide moisturizing benefits and to minimize cutaneous damage caused by surfactants. In fact, surfactants may damage protein structures and solubilize lipids. Soaps, defined as the alkali salts of fatty acids, are the oldest surfactants and are quite aggressive. Syndets (synthetic detergents) vary in composition and surfactant types (anionic, cationic, amphotheric, non‐ionic). These new skin cleansing products also contain preservatives, fragrances, and sometimes emollients, humectants and skin nutrients. We present a revision of the literature and discuss recent findings regarding skin cleansers.  相似文献   
998.
Rationale, aims and objectives Acute fever is the most common clinical symptom for infectious diseases. It is necessary to identify risk factors for infectious patients with acute fever and formulate activation criteria of early warning infectiosity score system (EWIS) to alert outpatient clinic doctors. Methods Logistic regression analysis was used to determine risk factors for infectious diseases from the clinical data of 758 patients with acute fever. Risk factors were weighted and an EWIS was formulated. A receiver operator characteristic (ROC) analysis of weighted cumulative scores was performed to evaluate the diagnostic accuracy of EWIS, and the Kappa test used to confirm diagnostic reliability. A χ2‐test for trend was applied to determine the relevance between EWIS and incidence of infectious diseases. Results Risk factors for infections included conjunctival hyperaemia, rash, diarrhoea, increased alanine aminotransferase, splenomegaly and abnormal percentage of peripheral neutrophils (NE%). Risk factors were weighted and tabulated. The areas under the ROC curves of the EWIS was 0.929 and ≥4 points predicted infectious diseases, and the Kappa values were 0.750. As the score increased, the incidence of infectious diseases increased. The areas under the ROC curves of the EWIS predicting on single viral and bacterial infectious diseases were 0.961 and 0.896, and the Kappa values were 0.807 and 0.701, respectively. Conclusions Risk factors for infections have been identified, quantified and formulated into a table of EWIS that have high diagnostic accuracy and reliability for the early identification of contagious diseases.  相似文献   
999.
Background Pre‐operative determination of primary melanoma thickness could be a tool to identify those patients who could be treated with radical primary tumour excision and sentinel lymph node biopsy in a single procedure. An excellent correlation between sonographic and histological measurement of maximal tumour thickness has been achieved using 20‐MHz transducers. Objective To show that widely available high resolution ultrasound with 12–15 MHz linear probe could also reliably assess the thickness of primary melanoma. Methods Sixty‐nine patients underwent ultrasound evaluation of 70 clinically and dermoscopically suspicious pigmented skin lesions before surgical excision. Results The sensitivity, specificity, positive and negative predictive values of ultrasound to detect melanoma > 1 mm were 92%, 92%, 95% and 81% respectively. The correlation between ultrasound and histological tumour thickness was very good [Pearson’s correlating index 0.823 (P < 0.001)]. Mean difference between sonographic and histological measurements was 0.045 mm with limits of agreement estimated at ?1.4 and +1.49, and a bias between two methods 45 μm. Conclusion Ultrasound examination with a 12–15 MHz linear transducer can reliably differentiate primary melanoma > 1 mm from those ≤ 1 mm.  相似文献   
1000.
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