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   576篇
  免费   19篇
  国内免费   2篇
耳鼻咽喉   8篇
儿科学   12篇
妇产科学   15篇
基础医学   129篇
口腔科学   15篇
临床医学   57篇
内科学   71篇
皮肤病学   6篇
神经病学   29篇
特种医学   18篇
外科学   75篇
综合类   19篇
一般理论   1篇
预防医学   48篇
眼科学   45篇
药学   30篇
中国医学   5篇
肿瘤学   14篇
  2024年   1篇
  2023年   5篇
  2022年   16篇
  2021年   22篇
  2020年   12篇
  2019年   15篇
  2018年   22篇
  2017年   11篇
  2016年   16篇
  2015年   15篇
  2014年   24篇
  2013年   30篇
  2012年   35篇
  2011年   44篇
  2010年   15篇
  2009年   33篇
  2008年   31篇
  2007年   39篇
  2006年   22篇
  2005年   33篇
  2004年   28篇
  2003年   28篇
  2002年   36篇
  2001年   3篇
  2000年   12篇
  1999年   12篇
  1998年   2篇
  1997年   2篇
  1996年   3篇
  1995年   3篇
  1994年   1篇
  1992年   2篇
  1991年   6篇
  1990年   2篇
  1989年   4篇
  1988年   3篇
  1985年   1篇
  1980年   1篇
  1979年   1篇
  1978年   2篇
  1970年   1篇
  1969年   1篇
  1965年   1篇
  1964年   1篇
排序方式: 共有597条查询结果,搜索用时 15 毫秒
41.
Tetrodotoxin (TTX) was localized as brown color in different tissues of an undescribed species of the nemertean genus Cephalothrix (phylum Nemertea) and a turbellarian Planocera reticulata (phylum Platyhelminthes) on light microscopy by means of a monoclonal anti-TTX antibody. In the Cephalothrix sp., TTX was recognized in the vesicles apically arranged in the bacillary cells in the epidermis, basal lamina, the granular cells in the proboscis epithelium, rhynchocoel epithelium, and the vesicles in the basal portion of the intestinal wall near the blood vessels and rhynchocoel. The excretory system and the ovum also showed positive reaction of TTX antigen-antibody. On the other hand, the hermaphrodite flatworm P. reticulata exhibited TTX antigen-antibody complex only in their ovum. To our knowledge, this is the first experimental effort on micro-distribution of TTX in invertebrates.  相似文献   
42.
This study aims to explore and examine the conjectures surrounding the utilization of family planning services among currently married couples of childbearing age in Renk County.This study has adopted a qualitative method to collect data on factors affecting the utilization of family planning services through focus group discussions and in-depth interviews, in rural and urban areas of Renk County. It targeted married women, men as well as unmarried men and women. The researchers conducted nine focus group discussions and nine interviews at both Jelhak (rural setting) and Renk (urban setting). The results suggested that the people of Renk County prefer to have large families and therefore choose not to use family planning methods. The data collected was analyzed by means of thematic analysis. This included the construction of a thematic framework, coding, editing and categorization of available data as well as the creation of sub-themes.The result also suggested that perception is a main factor that affects utilization of family planning services with a majority of the people in Renk and Jelhak preferring to have many children in order to increase the family size for some reasons. These are linked to religion, social stigma and taboo that are attached to childless people or users of family planning methods for birth control purposes.The responses revealed some variation in perception between rural (Jelhak) and urban (Renk) areas. Respondents from Renk area reported that some people use family planning services for economic reasons that involve alleviation of financial difficulties and provision of better education when the family size is small. On the other hand, rural people from Jelhak perceive family planning to be socially un-acceptable. Furthermore, men and women of Jelhak reported that after each birth of a child, married couples avoid sexual relationship for a period of two years as means of family planning. Women of both Urban and Rural settings reported intentions to use conventional methods of family planning without the knowledge of their spouses.  相似文献   
43.
Dieting is becoming a popular phenomenon among university students to achieve or maintain a healthy weight. The purpose of this study is to obtain a preliminary understanding of what dieting practices university students use in order to achieve their desirable body weight and to determine the magnitude of body dissatisfaction in relation to weight status among a sample of students (n=252) from the Lebanese American University in Beirut, Lebanon. Students filled out a self-reported questionnaire that included questions on their dieting and physical activity practices in addition to the body shape questionnaire (BSQ). Weight and height were measured to calculate body mass index. Percentage body fat was measured using Tanita scale body fat analyzer 300A. The outcome of this study showed that smoking and unhealthy dieting practices were not common among students (only 26% reported smoking, 8% reported taking laxatives and 4% taking diet pills). Half of the students reported practicing regular physical activity. Multivitamin intake was also not popular among students. BSQ scores indicate that the majority of students were not worried about their body image perception (64% reported not being worried, 19% were slightly worried, 12% were moderately worried and 5% were extremely worried). A gender difference was observed in the BSQ scores, as 89% of the "extremely worried" students were females. Collectively, results indicate that unhealthy dieting practices are uncommon among students. However, developing health promotion awareness' programs to promote good self image within the concept of a realistic healthy weight will be beneficial, especially among females.  相似文献   
44.
The present study was designed to explore the possible antioxidant and hypolipidemic effects of the aqueous extract of Ajuga iva (0.5% in the diet) in rats fed a high-cholesterol (1%) diet (HCD). The results indicated that the HCD-Ai versus HCD treatment led to many changes in biochemical parameters. They showed a decrease of plasma total cholesterol (TC) and VLDL-cholesterol but an increase of HDL(2)-cholesterol. The triacylglycerol contents were reduced in plasma and in VLDL. The lipid peroxidation determined by TBARS was decreased by 75% in plasma. TBARS in liver, heart and kidneys were highly reduced excepted in the adipose tissue. Ajuga iva treatment enhanced superoxide dismutase activity in liver and kidney. Glutathione reductase activity was lowered in adipose tissue but increased in liver and in kidney. A significant increase was noted in glutathione peroxidase activity in liver, heart and kidney but a low value in adipose tissue was observed. In conclusion, the present study demonstrates that in addition to its potent TG and TC-lowering effects, Ajuga iva is effective in improving the antioxidant status by reducing lipid peroxidation in plasma and tissues and enhancing the antioxidant enzymes in rats fed high-cholesterol diet. Furthermore, Ajuga iva may reduce intestinal cholesterol absorption.  相似文献   
45.

Background

The spectrum of lung neuroendocrine tumors (NETs) encompasses low grade typical carcinoid (TC), intermediate grade atypical carcionid (AC) and high grade, both large cell neuroendocrine carcinoma (LCNEC) and small cell lung cancer (SCLC), with extreme differences in management and survival.

Objective

To study clinicopathologic and prognostic factors affecting survival of lung NETs.

Patients and methods

This is a retrospective study evaluating 35 patients with primary lung NETs treated at National Cancer Institute of Egypt (NCI-E) between January 2010 and December 2014. Pathological diagnosis depended on definite morphology and positivity to at least one of the neuroendocrine markers by immunohistochemistry.

Results

The mean age of the patients was 53?±?11.2?years with male predominance. Performance status (PS) I was encountered in 48.6%. SCLC was the prevalent histology in 68.6%, followed by LCNEC & TC in 20 & 11.4%, respectively. Curative surgery was employed in 100 & 57% of TC & LCNEC patients, respectively. Stage IV was anticipated in 87.5 & 43% of SCLC & LCNEC, respectively. For the entire cohort, the median event-free survival (EFS) and overall survival (OS) were 8.0 and 13.7?months, respectively, whereas the 3-year EFS and OS were 17.8 & 20%, respectively. SCLC patients showed significantly the worst OS compared to other NETs (p?=?0.001). Patients who presented with stage IV and PS?>?I demonstrated significantly shorter OS than those with locoregional and PS I (p?=?0.00001 & p?=?0.002, respectively).

Conclusions

SCLC subtype, stage IV and initial PS?>?I are poor prognostic factors for lung NETs associated with shorter survival. This conclusion needs to be confirmed by larger studies.  相似文献   
46.
47.
Degeneration of the human lumbar spine ligaments. An ultrastructural study   总被引:6,自引:0,他引:6  
The fine structural alterations in human lumbar spine ligaments were studied in tissue samples obtained from 8 young patients operated upon for idiopathic scoliosis and from 10 adult patients operated upon for herniated discs. The ultrastructure of the scoliotic ligaments was found to be normal. The majority of cells encountered were the fibroblastic-like cells. The collagen-proteoglycans interaction was similar to that described in other normal soft tissues. However, two forms of degenerative changes were demonstrated in posterior ligaments of patients with herniated discs. Metaplasia of ligamentous tissue into fibrocartilage was a common finding. The fibroblasts were replaced by chondrocytes. A few cells which had suffered necrosis were found. Alterations in the collagen-proteoglycans arrangement were also evidenced. This form of degeneration resembled that commonly associated with wear and tear phenomena. A second form of degeneration due to ageing was found to coexist with the aforementioned alterations.  相似文献   
48.
Neuroimaging of stroke: a review   总被引:5,自引:0,他引:5  
Advances in neuroimaging technology during the past 30 years have resulted in a virtual explosion in the amount of pathologic information that can be obtained in the clinical stroke setting. This neuroimaging revolution has led to a much better understanding of cerebrovascular and tissue pathology, creating a wide array of opportunities for acute treatment and secondary prevention. Advances include early and accurate detection of ischemic and infarcted tissue and the ability to reveal hypoperfused tissue at risk. Clinicians are increasingly able to noninvasively detect embolic and atherothrombotic intravascular lesions. Vascular lesions associated with stroke can be characterized through endovascular neuroimaging techniques and repaired by various means. In this article, we provide an overview and update on the various techniques used in the neuroimaging of stroke and intracranial hemorrhage, including computed tomography, magnetic resonance imaging, ultrasound, and catheter angiography. We outline the specific role of each modality in clinical practice.  相似文献   
49.
50.
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