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   350篇
  免费   26篇
  国内免费   52篇
耳鼻咽喉   3篇
儿科学   10篇
妇产科学   3篇
基础医学   45篇
口腔科学   16篇
临床医学   66篇
内科学   75篇
皮肤病学   12篇
神经病学   5篇
特种医学   67篇
外科学   36篇
综合类   9篇
预防医学   12篇
眼科学   1篇
药学   41篇
肿瘤学   27篇
  2023年   2篇
  2021年   5篇
  2020年   3篇
  2019年   6篇
  2018年   7篇
  2017年   7篇
  2016年   10篇
  2015年   10篇
  2014年   14篇
  2013年   15篇
  2012年   8篇
  2011年   17篇
  2010年   16篇
  2009年   13篇
  2008年   10篇
  2007年   52篇
  2006年   12篇
  2005年   18篇
  2003年   3篇
  2002年   7篇
  2001年   11篇
  2000年   8篇
  1999年   4篇
  1998年   18篇
  1997年   11篇
  1996年   21篇
  1995年   13篇
  1994年   19篇
  1993年   10篇
  1992年   1篇
  1991年   2篇
  1990年   5篇
  1989年   9篇
  1988年   5篇
  1987年   5篇
  1986年   8篇
  1985年   6篇
  1984年   3篇
  1982年   1篇
  1981年   4篇
  1980年   3篇
  1979年   1篇
  1978年   3篇
  1977年   6篇
  1976年   5篇
  1975年   4篇
  1973年   1篇
  1971年   1篇
  1962年   1篇
  1959年   1篇
排序方式: 共有428条查询结果,搜索用时 15 毫秒
1.
2.
Uroscopy in the 21st century: high-field NMR spectroscopy   总被引:1,自引:1,他引:0  
From the experiments described, it can be seen that there are different research approaches that can be taken and these are summarized in Table 1. Whereas much scientific research is principally hypothesis led, there remains, nevertheless, an important place for exploratory research. High resolution NMR can measure, directly and simultaneously, a wide range of endogenous metabolites in biological fluids and has the unique capability of providing structural information on the metabolites detected. It has proved to be a powerful research tool with which to study inherited metabolic diseases, renal disease, drug metabolism, and toxicity, and can be used to monitor the effects of drug therapy. For instance, by using a library of experimental toxins one can map the metabolic profile of site-specific nephron injury. With this approach in man one could eventually take an unknown disease such as Balkan nephropathy and predict the initial site of tubular injury, the mode of injury and therefore the kind of toxin capable of producing that injury. NMR spectroscopic techniques are still advancing rapidly, with ever increasing sensitivity and sophistication of NMR pulse sequences to enhance structural elucidation in complex mixtures. Given the advances in directly coupled HPLC-NMR and even HPLC-NMR-mass spectroscopy it is likely that these technologies in conjunction with pattern recognition will make major contribution to our understanding of renal processes and provide new diagnostic insights in the 21st century.   相似文献   
3.

Background  

Correct diagnosis in psychiatry may be improved by novel diagnostic procedures. Computerized Decision Support Systems (CDSS) are suggested to be able to improve diagnostic procedures, but some studies indicate possible problems. Therefore, it could be important to investigate CDSS systems with regard to their feasibility to improve diagnostic procedures as well as to save time.  相似文献   
4.
Cystic hypersecretory carcinoma (CHC) is a rare variant of intraductal carcinoma. A CHC in a 50-year-old woman was excised and processed for light and electron microscopy and immunohistochemistry. The tumor had a marked cystic appearance. The walls of the cysts consisted of epithelial and myoepithelial cells and a well-developed basement membrane. The epithelial cells contained well-developed rough-surfaced endoplasmatic reticulum and Golgi apparatus. Secretory granules were not detected, with the exception of a few mucus-producing cells. The secretion was predominantly homogenous, reminiscent of thyroid colloid, and demonstrated distinct PAS positivity. The cells displayed a strong labeling with epithelial membrane antigen (EMA) and EMA-positive structures were observed within the intraluminal secretion, too. Some of these were stained by alcian blue. In addition, the colloid-like material was admixed with mucus showing a filamentous internal structure and lipid droplets resulting in some heterogenity of the secretion. Intraductal micropapillary proliferation in some of the cysts and adjacent nondistended ducts was a further defining feature of the tumor. Steroid hormone receptor and Ki-67 proliferation marker immuno his Tochemistry showed scattered positivity among the tumor cells. These results are in agreement with previous observations and further clarify the nature of this low-grade in situ cancer.  相似文献   
5.
6.
7.
The International Journal of Cardiovascular Imaging - There is conflicting evidence regarding the significance of iatrogenic atrial septal defects (iASDs) after transseptal puncture during...  相似文献   
8.

BACKGROUND:

Flavonoids are polyphenolic substances with antioxidant properties, and they are found in different vegetables and fruits. Epidemiological studies have shown that the consumption of flavonoids reduces the prevalence of cardiovascular diseases. The use of synthetic antioxidants, however, has been limited because of their toxicity. Therefore, medical researchers have intensified their quest to find natural antioxidants.

OBJECTIVES:

To investigate the effect of several pure flavonoids, such as kaempferol, quercetin, morin and rutin, on red blood cell hemolysis and evaluate their -SH capacity as an indicator of membrane protection.

METHODS:

The rate of hemolysis and cell membrane -SH capacity were determined by spectrophotometry. Red blood cell peroxidation was induced using 2,2′-azo-bis-(2-amidinopropane) dihydrochloride. The effect of each flavonoid on hemolysis was examined at three concentrations (0.5 μg/mL, 5 μg/mL and 10 μg/mL), however, only the greatest concentration (10 μg/mL) of each flavonoid was used to study the effect on -SH groups.

RESULTS:

In all cases, the antioxidant activity was dose-dependent. Rutin showed the highest inhibitory effect on hemolysis among flavonoids (42.5%). The protective effect of kaempferol, rutin and morin against -SH group oxidation measured 7.7%, 23.3% and 26.4%, respectively.

CONCLUSIONS:

Results showed that flavonoids and flavonoid-containing plants can be used as natural antioxidants for the treatment and prevention of disease conditions, the pathogenesis of which is mediated by lipid peroxidation.  相似文献   
9.
Graefe's Archive for Clinical and Experimental Ophthalmology - To assess spontaneous blinking and anomalous eyelid movements in patients with hemifacial spasm with an emphasis on interocular...  相似文献   
10.
Collagens in the extracellular matrix (ECM) provide a physical barrier to tumor immune infiltration, while also acting as a ligand for immune inhibitory receptors. Transforming growth factor-β (TGF-β) is a key contributor to shaping the ECM by stimulating the production and remodeling of collagens. TGF-β activation signatures and collagen-rich environments have both been associated with T cell exclusion and lack of responses to immunotherapy. Here, we describe the effect of targeting collagens that signal through the inhibitory leukocyte-associated immunoglobulin-like receptor-1 (LAIR-1) in combination with blockade of TGF-β and programmed cell death ligand 1 (PD-L1). This approach remodeled the tumor collagenous matrix, enhanced tumor infiltration and activation of CD8+ T cells, and repolarized suppressive macrophage populations, resulting in high cure rates and long-term tumor-specific protection across murine models of colon and mammary carcinoma. The results highlight the advantage of direct targeting of ECM components in combination with immune checkpoint blockade therapy.  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