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   24419篇
  免费   1202篇
  国内免费   120篇
耳鼻咽喉   317篇
儿科学   500篇
妇产科学   323篇
基础医学   3222篇
口腔科学   514篇
临床医学   1680篇
内科学   6587篇
皮肤病学   335篇
神经病学   1805篇
特种医学   1078篇
外科学   3809篇
综合类   107篇
一般理论   3篇
预防医学   619篇
眼科学   487篇
药学   1720篇
中国医学   96篇
肿瘤学   2539篇
  2023年   155篇
  2022年   325篇
  2021年   500篇
  2020年   232篇
  2019年   380篇
  2018年   454篇
  2017年   362篇
  2016年   432篇
  2015年   464篇
  2014年   592篇
  2013年   743篇
  2012年   1244篇
  2011年   1317篇
  2010年   715篇
  2009年   583篇
  2008年   1072篇
  2007年   1196篇
  2006年   1125篇
  2005年   1233篇
  2004年   1087篇
  2003年   1087篇
  2002年   1083篇
  2001年   738篇
  2000年   773篇
  1999年   724篇
  1998年   318篇
  1997年   245篇
  1996年   262篇
  1995年   226篇
  1994年   210篇
  1993年   176篇
  1992年   545篇
  1991年   539篇
  1990年   491篇
  1989年   476篇
  1988年   381篇
  1987年   338篇
  1986年   360篇
  1985年   334篇
  1984年   234篇
  1983年   199篇
  1982年   104篇
  1980年   108篇
  1979年   183篇
  1978年   116篇
  1977年   113篇
  1974年   102篇
  1972年   105篇
  1969年   97篇
  1968年   100篇
排序方式: 共有10000条查询结果,搜索用时 29 毫秒
1.

Background

Photosensitizers used for photodynamic therapy (PDT) to treat dermatologic disease are metabolized into mainly protoporphyrin IX (PpIX), which has five absorption wavelength peaks: 410?nm, 510?nm, 545?nm, 580?nm, and 630?nm. Although only red light around 635?nm and blue light around 400?nm are used as light sources for PDT, the efficiency of PDT might be improved by using multiple wavelengths, including those that correspond to the other absorption peaks of PpIX. Furthermore, because the target disease often occurs on the face, a flexible-type light-source unit that can be fitted to the lesion without unnecessarily exposing the mucous membranes, e.g., the eyes, nostrils, and mouth, is preferred.

Objective

We investigated the efficacy of a flexible light-emitting diode (LED) unit that emits multiple wavelengths to improve PDT effects.

Methods

HaCaT cells were incubated with 5-ALA and subsequently irradiated with either a single wavelength or sequentially with two wavelengths. Cell viability and reactive oxygen species were analyzed. Nude mice were implanted with COLO679 cells by subcutaneous injection into the flank. 5-ALA was subcutaneously injected into the tumor. The tumor was irradiated with 50?J/cm2 (day 0) and assessed daily until day 21.

Results

The synergistic PDT effects of dual-wavelength irradiation and reactive oxygen species production were highest with the 405-nm and 505-nm wavelength combination. This dual wavelength combination was also the most effective in vivo.

Conclusion

We could therefore conclude that dual-wavelength PDT is an efficient strategy for improving the therapeutic effects of PDT. Using a flexible LED unit is expected to achieve more uniform irradiation of uneven areas.  相似文献   
2.
3.
4.
5.

Background

There were few studies assessed the postoperative sarcopenia in patients with cancers. The objective of present study was to assess whether postoperative development of sarcopenia could predict a poor prognosis in patients with adenocarcinoma of esophagogastric junction, (AEG) and upper gastric cancer (UGC).

Methods

Patients with AEG and UGC who were judged as non-sarcopenic before surgery were reassessed the presence of postoperative development of sarcopenia 6 months after surgery. Patients were divided into the development group or non-development group, and clinicopathological factors and prognosis between these two groups were analyzed.

Results

The 5-year overall survival rates were significantly poorer in the development group than non-development group (68.0% vs. 92.6%, P?=?0.0118). Multivariate analyses showed that postoperative development of sarcopenia was an independent prognostic factor for poor overall survival (P?=?0.0237).

Conclusions

Postoperative development of sarcopenia was associated with a poor prognosis in patients with AEG and UGC.  相似文献   
6.
<正>Stroke is a leading cause of mortality and severe neurological disability worldwide; however, curative therapeutic options are limited. Although recanalization therapy using endovascular thrombectomy has demonstrated great benefits in the functional outcome of patients with acute ischemic stroke, the rate of excellent clinical outcomes remains limited. Therefore, the current recanalization  相似文献   
7.
8.
9.
10.
The feasibility of ventilation imaging with hyperpolarized (HP) 129Xe MRI has been investigated for quantitative and regional assessment of ventilation in spontaneously breathing mice. The multiple breath ventilation imaging technique was modified to the protocol of spontaneous inhalation of HP 129Xe delivered continuously from a 129Xe polarizer. A series of 129Xe ventilation images was obtained by varying the number of breaths before the 129Xe lung imaging. The fractional ventilation, r, was successfully evaluated for spontaneously breathing mice. An attempt was made to detect ventilation dysfunction in the emphysematous mouse lung induced by intratracheal administration of porcine pancreatic elastase (PPE). As a result, the distribution of fractional ventilation could be visualized by the r map. Significant dysfunction of ventilation was quantitatively identified in the PPE‐treated group. The whole‐lung r value of 0.34 ± 0.01 for control mice (N = 4) was significantly reduced, to 0.25 ± 0.07, in PPE‐treated mice (N = 4) (p = 0.038). This study is the first application of multiple breath ventilation imaging to spontaneously breathing mice, and shows that this methodology is sensitive to differences in the pulmonary ventilation. This methodology is expected to improve simplicity as well as noninvasiveness when assessing regional ventilation in small rodents. Copyright © 2014 John Wiley & Sons, Ltd.  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