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   6446篇
  免费   719篇
  国内免费   32篇
耳鼻咽喉   32篇
儿科学   153篇
妇产科学   115篇
基础医学   893篇
口腔科学   103篇
临床医学   809篇
内科学   1599篇
皮肤病学   241篇
神经病学   554篇
特种医学   382篇
外科学   591篇
综合类   90篇
一般理论   2篇
预防医学   891篇
眼科学   55篇
药学   351篇
中国医学   3篇
肿瘤学   333篇
  2023年   75篇
  2022年   35篇
  2021年   73篇
  2020年   94篇
  2019年   81篇
  2018年   140篇
  2017年   103篇
  2016年   137篇
  2015年   149篇
  2014年   211篇
  2013年   289篇
  2012年   336篇
  2011年   371篇
  2010年   201篇
  2009年   203篇
  2008年   312篇
  2007年   312篇
  2006年   283篇
  2005年   260篇
  2004年   270篇
  2003年   215篇
  2002年   225篇
  2001年   215篇
  2000年   166篇
  1999年   184篇
  1998年   143篇
  1997年   125篇
  1996年   126篇
  1995年   108篇
  1994年   106篇
  1993年   85篇
  1992年   105篇
  1991年   86篇
  1990年   103篇
  1989年   133篇
  1988年   104篇
  1987年   104篇
  1986年   98篇
  1985年   88篇
  1984年   55篇
  1983年   53篇
  1982年   47篇
  1981年   49篇
  1979年   52篇
  1978年   32篇
  1977年   41篇
  1976年   41篇
  1975年   34篇
  1973年   34篇
  1971年   38篇
排序方式: 共有7197条查询结果,搜索用时 78 毫秒
31.
32.
Integrated surveillance of infectious multi-source diseases using a combination of epidemiology, ecology, genetics and evolution can provide a valuable risk-based approach for the control of important human pathogens. This includes a better understanding of transmission routes and the impact of human activities on the emergence of zoonoses. Until recently New Zealand had extraordinarily high and increasing rates of notified human campylobacteriosis, and our limited understanding of the source of these infections was hindering efforts to control this disease. Genetic and epidemiological modeling of a 3-year dataset comprising multilocus sequence typed isolates from human clinical cases, coupled with concurrent data on food and environmental sources, enabled us to estimate the relative importance of different sources of human disease. Our studies provided evidence that poultry was the leading cause of human campylobacteriosis in New Zealand, causing an estimated 58–76% of cases with widely varying contributions by individual poultry suppliers. These findings influenced national policy and, after the implementation of poultry industry-specific interventions, a dramatic decline in human notified cases was observed in 2008. The comparative-modeling and molecular sentinel surveillance approach proposed in this study provides new opportunities for the management of zoonotic diseases.  相似文献   
33.
BACKGROUND: Basal cell carcinoma (BCC) is the most common type of skin cancer. One of the main problems with BCC is the risk of local recurrence of the tumor after treatment. This is mainly due to its irregular outgrowths, which cannot be detected clinically. OBJECTIVE: To better understand the tumor morphology and growth pattern of BCC, we tried to develop a method that provides a precise three-dimensional model of the tumor. METHODS: Because Mohs surgery provides the best overview of the tumor and the tumor margins (both lateral and in depth), the reconstruction was based on slides from Mohs surgery. After digitization and processing of the slides, the tumor was then surrounded by a Mohs surgeon on a computer screen. These selections (lines) were used for a three-dimensional reconstruction of the tumor using MedSurf3D software. RESULTS: This method allows three-dimensional reconstruction of any given BCC. The MedSurf3D software enables visualization of a three-dimensional model of the tissue, which is removed during the surgical procedure. CONCLUSIONS: Three-dimensional reconstruction is a fascinating tool that might improve our understanding of the behavior, growth pattern, and tumor morphology of BCCs. This technique might also be useful in other fields of cutaneous oncology, such as the calculation of the tumor volume of melanomas.  相似文献   
34.
SIR, We appreciate the comments of Kleiman et al., which serveto  相似文献   
35.
Purpose. The objective of this study is to correlate drug release mechanism with measured drug concentration profiles in gel layers of Carbopol® matrices containing mesalamine or benzoic acid. Methods. Release rate experiments with Carbopol® matrices were performed using a rotating disk apparatus. Matrices were frozen and the gel layer in the matrices was sliced using a microtome in a cryostat. Drug concentration profiles were determined by direct measurement of the concentration of the drug in the gel slices. The pH of the slices was measured using microelectrodes, and water content was measured by Karl Fisher titration. Results. The concentration gradient in mesalamine matrices decreased over time and correlated with square root of time release rate kinetics. The concentration profiles of benzoic acid were unchanged over time and correlated with zero order release rate kinetics. Carbopol gel layers were highly hydrated (93–95% water). Gel layers in matrices with mesalamine had a more alkaline microenvironmental pH. This higher pH resulted in increased growth of the thickness of the gel layer and a reduction drug diffusivity in comparison to benzoic acid matrices. Conclusions. The release rate kinetics of mesalamine and benzoic acid correlated to the measured concentration profiles. The shape of the concentration profiles is determined by the rate of growth of the Carbopol® gel layer and drug diffusivity.  相似文献   
36.
Of 74 paediatric inpatients with acute glomerulonephritis, 58 (78%) had a raised (greater than 1/200) antistreptolysin O titre. Serum C3 concentration was low in 73, but returned to normal within six weeks. Streptococcal infection remains the commonest cause of acute nephritis in children in Hong Kong, possibly due to overcrowded living conditions.  相似文献   
37.
38.
39.
40.
Six patients with upper cervical spine ossicles and Down syndrome from a study population of 184 are described. The average age was 20.6 years at the time of diagnosis. Three of the patients were involved in tumbling. Radiographic anatomy of the ossicles and the dens, as well as serial radiographs in three of the six patients, suggest that this represents an avulsion of the upper end of the dens rather than an occipital vertebrae, ossiculum terminale, or os odontoideum, as previously described. The authors advocate restriction of high-risk activities for all patients with Down syndrome.  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