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   396篇
  免费   22篇
耳鼻咽喉   3篇
儿科学   38篇
妇产科学   7篇
基础医学   59篇
口腔科学   8篇
临床医学   27篇
内科学   84篇
皮肤病学   1篇
神经病学   38篇
特种医学   6篇
外科学   72篇
综合类   3篇
一般理论   2篇
预防医学   13篇
眼科学   10篇
药学   4篇
中国医学   2篇
肿瘤学   41篇
  2023年   3篇
  2022年   4篇
  2021年   6篇
  2020年   8篇
  2019年   4篇
  2018年   14篇
  2017年   12篇
  2016年   10篇
  2015年   9篇
  2014年   10篇
  2013年   29篇
  2012年   25篇
  2011年   21篇
  2010年   13篇
  2009年   15篇
  2008年   16篇
  2007年   23篇
  2006年   13篇
  2005年   23篇
  2004年   15篇
  2003年   14篇
  2002年   8篇
  2001年   4篇
  1999年   11篇
  1998年   6篇
  1997年   5篇
  1996年   4篇
  1995年   8篇
  1994年   2篇
  1993年   4篇
  1992年   6篇
  1991年   8篇
  1990年   6篇
  1989年   3篇
  1988年   2篇
  1987年   2篇
  1985年   3篇
  1984年   3篇
  1982年   5篇
  1979年   2篇
  1978年   2篇
  1977年   2篇
  1975年   3篇
  1974年   5篇
  1973年   5篇
  1972年   2篇
  1970年   4篇
  1969年   5篇
  1968年   5篇
  1967年   2篇
排序方式: 共有418条查询结果,搜索用时 0 毫秒
1.
Highly malignant cell lines and low-malignant cell lines isolated from three different methylcholanthrene-induced murine fibrosarcomas were examined for their ability to attach to plastic dishes and collagen-coated dishes under serumfree conditions and in the presence of serum. Most of the cells from the three highly malignant lines attached and spread under all conditions. By 72h, there was a significant increase in the number of cells indicating that at least some of the cells had undergone division (even in the absence of serum). In contrast, fewer of the cells from the three low-malignant lines attached and spread on the plastic or collagen substrates in the absence of serum or in the presence of 0.1 per cent serum. However, when 15g laminin per dish was added along with the lowmalignant cells, they then attached and spread on the plastic and collagen-coated dishes. Previous studies have indicated that the highly malignant lines express cell surface antigens that cross-react with laminin while the low-malignant cell lines do not. We speculate that the differences between the high- and low-malignant cells in the expression of cell surface laminin-like antigens contribute to the dissimilarities in attachment and spreading capacity. These differences may also contribute to the dissimilarity between these cells in malignant potential.  相似文献   
2.

Background  

To determine whether the use of an electronic, sensor based stethoscope affects the cardiac auscultation skills of undergraduate medical students.  相似文献   
3.
The spectrum of somatic TP53 single basepair substitutions detected in 955 cancers was compared with that of 2,224 different germline mutations in 279 different human genes (other than TP53), reported as the cause of inherited disease. This comparison reveals that, disregarding a relatively small subset (12%) of TP53 mutations that probably result from the action of exogenous mutagens, both the relative rates and the nearest-neighbor spectra of single basepair substitutions are similar in the two datasets. This spectral resemblance suggests that a substantial proportion of cancer-associated somatic TP53 mutations result from endogenous cellular mechanisms. The likelihood of clinical observation of a particular mutation type differs, however, between tumors and genetic diseases, when the chemical properties of the resulting amino acid substitutions are considered. Together with a sixfold higher observation likelihood for mutations at evolutionary conserved residues, this finding argues that selection is a critical factor in determining which TP53 mutations are found to be associated with human cancer. © 1995 Wiley-Liss, Inc.  相似文献   
4.
The causes of the "endothelial dysfunction" accompanying preeclampsia are unknown. Women with preeclampsia have a marked hyperlipidemia which reflects altered lipid metabolism. We asked if the hyperlipidemic sera of preeclamptic women could cause altered endothelial cell properties. Cultured endothelial cells were incubated with sera from women with preeclampsia (PE) or normal pregnancies as controls. Fifty PE-sera were tested and in 45 cases the endothelial cells acquired a large number of sudanophilic granules which by electron microscopy had lipid appearance. In 31 incubations with 31 individual control sera cellular lipid granules were observed in 4 cases. The cellular triglyceride content was increased to 153 +/- 30 compared to 48 +/- 10 micrograms/mg cell protein in the control cells. Furthermore, the endothelial release of prostacyclin, measured as 6-keto PGF1 alpha, was 8.8 +/- 0.6 ng/mg cell protein in cells incubated with PE-sera as compared to 40.3 +/- 6.4 ng/mg in the control cells. Conclusion: The hyperlipidemic sera from preeclamptic women induced triglyceride accumulation in cultured endothelial cells. This was accompanied by altered endothelial function as demonstrated by reduced prostacyclin release.  相似文献   
5.
Abstract Background. Oral intake (60 ml daily) over 12 days in eight healthy volunteers of an immunostimulatory extract based on the medicinal mushroom Agaricus blazei Murill (AbM (AndoSan(?))), reduced the monocyte and granulocyte release of mainly proinflammatory cytokines in vivo, suggesting an anti-inflammatory effect. In this foremost in vivo study, the aim was to examine the effect of such AndoSan(?) consumption on the expression of adhesion molecules CD11b, CD11c and CD62L and production of reactive oxygen species (ROS) in leukocytes. Methodology/Principal findings. As shown by flow cytometry, there was a significant increase of CD62L expression on monocytes and granulocytes from before (day 0) compared with 12 days after daily AndoSan(?) consumption. However, only minor alterations and no clear trend in the expression of CD11b and CD11c were detected. Intracellular ROS (mainly superoxide ion) were significantly reduced in these cells from days 0 to 12. Conclusions/Significance. These results support that oral intake of AndoSan(?) exhibits an anti-inflammatory effect in humans in vivo.  相似文献   
6.
In a randomized prospective study, we selected 15 patients for arthroscopic subacromial decompression (ASD) and 19 patients for open subacromial decompression (OSD). All had impingement syndrome (Neer grade II), and had been unsuccessfully treated without surgery for more than 6 months. The UCLA Shoulder Rating Scale, Visual Analogue Scales for pain and satisfaction, isokinetic dynamometer recordings and physical testing were assessed preoperatively and at 1 (except isokinetic testing), 3, 6, and 12 months, and, finally, 8 years after surgery. We found essentially no differences in the clinical tests between the groups during this period. The use of ASD or OSD seems to be a matter of cosmesis and personal preference.  相似文献   
7.

Background

This single-institution, consecutive series of transsphenoidal procedures included all patients in a defined population of 2.6 million inhabitants who underwent surgery during a specific time period.

Objective

We sought to determine the surgical complication rate and overall survival rate after transsphenoidal surgery for pituitary adenoma.

Methods

All transsphenoidal procedures for histologically verified pituitary adenomas performed between September 2002 and February 2011 at our institution were included in this study. The data were obtained from a prospectively collected database and from reviewing medical records. No patients were lost to follow-up, and the median follow-up time was 28 months.

Results

A total of 506 transsphenoidal procedures were performed on 446 patients. There were 268 microscopic and 238 endoscopic procedures involving 352 non-functioning and 154 hormone-secreting adenomas. A total of 73 % of the procedures were primary surgeries, and 27 % were repeat surgeries for tumor recurrence. The overall complication rate was 9.1 %. The three most frequent complications were cerebrospinal fluid (CSF) leakage (4.7 %), meningitis (2 %), and visual deterioration (2 %). Multivariate analyses showed that the overall risk for complications increased with older age, surgery for recurrent tumors, and surgery performed by a low-volume surgeon. There was no significant difference in the overall complication rate between the microsurgical and endoscopic techniques. The rate of surgical mortality was 0.6 %, and the overall survival rates at 1 and 5 years were 95 % and 90 %, respectively. The only negative predictor of survival was older age.

Conclusions

Transsphenoidal surgery for pituitary adenomas has a low complication rate and a low rate of mortality. We did not find a significant difference in the complication rate between endoscopic and microscopic techniques.  相似文献   
8.
A system for robotically assisted retinal surgery has been developed to rapidly and safely place lesions on the retina for photocoagulation therapy. This system provides real-time, motion stabilized lesion placement for typical irradiation times of 100 ms. The system consists of three main subsystems: a digital-based global tracking subsystem; a fast, analog local tracking subsystem; and a confocal reflectance subsystem to control lesion parameters dynamically. We have reported previously on these individual subsystems. This paper concentrates on the development of a second hybrid system prototype. Considerable progress has been made toward reducing the footprint of the optical system, simplifying the user interface, fully characterizing the analog tracking system, using measurable lesion reflectance parameters to develop a noninvasive method to infer lesion depth, and integrating the subsystems into a seamless hybrid system. These system improvements and progress toward a clinically significant system are covered in detail within this paper. The tracking algorithms and concepts developed for this project have considerable potential for application in many other areas of biomedical engineering.  相似文献   
9.
We report HLA-A, -C, -B, -DRB1, -DQB1 and -DPB1 allele frequencies and estimated haplotype frequencies from 4514 healthy Norwegians who volunteered to participate in the Norwegian Bone Marrow Donor Registry. HLA genotyping was conducted on a Next Generation Sequencing platform. Data were analyzed using Arlequin and Pypop software. No significant deviations from Hardy-Weinberg Equilibrium were noted at any of the loci studied. We discuss the representability for the Norwegian population and argue that the presented HLA data could serve as a Norwegian reference panel.  相似文献   
10.

Background

The association between low birth weight (LBW) and increased risk of obesity, hypertension and cardiovascular disease later in life is well documented in epidemiological studies. However, clinical follow-up studies of LBW populations have only partly supported this.

Aims

Evaluate associations between LBW and body fat, blood pressure (BP), lung and endothelial function, and maximal oxygen uptake (VO2max) in 18 year old young adults.

Subjects

Thirty-seven subjects born prematurely with birth weight < 1501 g (VLBW group), 47 born at term with low weight (< 10th centile) for gestational age (SGA group) and 63 controls with normal birth weight participated in the study.

Outcome measures

Anthropometric measurements, BP, endothelial function, lung function and VO2max were recorded.

Results

Both LBW groups were shorter, lighter, had smaller head circumference and higher subscapular-to-triceps skinfold-ratio than controls. Systolic and mean arterial BP was higher in the VLBW compared with the control group, whereas there were no differences between the groups in endothelial function. The VLBW group had reduced dynamic lung volumes lower carbon monoxide transfer factor and lower VO2max compared with controls. In particular young adults born VLBW who were also growth retarded in utero had higher indices of central body fat, higher BP and lower VO2max.

Conclusion

We found that very preterm birth, but not growth retardation at term, was associated with higher BP and a less favourable fat distribution. In particular, the young adults born VLBW who were also growth retarded in utero had less favourable outcomes.  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