收费全文 | 6871篇 |
免费 | 298篇 |
国内免费 | 26篇 |
耳鼻咽喉 | 120篇 |
儿科学 | 59篇 |
妇产科学 | 35篇 |
基础医学 | 978篇 |
口腔科学 | 153篇 |
临床医学 | 383篇 |
内科学 | 1574篇 |
皮肤病学 | 101篇 |
神经病学 | 301篇 |
特种医学 | 327篇 |
外科学 | 1426篇 |
综合类 | 12篇 |
一般理论 | 1篇 |
预防医学 | 158篇 |
眼科学 | 133篇 |
药学 | 522篇 |
中国医学 | 17篇 |
肿瘤学 | 895篇 |
2022年 | 59篇 |
2021年 | 122篇 |
2020年 | 60篇 |
2019年 | 84篇 |
2018年 | 117篇 |
2017年 | 101篇 |
2016年 | 104篇 |
2015年 | 108篇 |
2014年 | 141篇 |
2013年 | 185篇 |
2012年 | 308篇 |
2011年 | 305篇 |
2010年 | 168篇 |
2009年 | 162篇 |
2008年 | 291篇 |
2007年 | 299篇 |
2006年 | 300篇 |
2005年 | 292篇 |
2004年 | 303篇 |
2003年 | 296篇 |
2002年 | 330篇 |
2001年 | 250篇 |
2000年 | 225篇 |
1999年 | 209篇 |
1998年 | 85篇 |
1997年 | 80篇 |
1996年 | 53篇 |
1995年 | 56篇 |
1994年 | 55篇 |
1993年 | 51篇 |
1992年 | 178篇 |
1991年 | 184篇 |
1990年 | 158篇 |
1989年 | 159篇 |
1988年 | 156篇 |
1987年 | 166篇 |
1986年 | 132篇 |
1985年 | 127篇 |
1984年 | 79篇 |
1983年 | 55篇 |
1982年 | 32篇 |
1979年 | 62篇 |
1978年 | 35篇 |
1975年 | 31篇 |
1974年 | 32篇 |
1973年 | 36篇 |
1971年 | 41篇 |
1970年 | 33篇 |
1968年 | 41篇 |
1967年 | 33篇 |
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Methods: Individuals who visited the outpatient clinic or were admitted to the palliative care unit were eligible. Patients with a performance status of 4 and/or those unable to complete questionnaires were excluded. PA was evaluated using a bioanalyzer device. The correlation coefficient between PA and the variables of interest was analyzed.
Results: A total of 102 patients were analyzed. PA was weakly correlated with age (ρ = ?0.22), performance status (ρ = ?0.30), functional well-being (ρ?=?0.20), anorexia/cachexia subscale (ρ?=?0.22), and Functional Assessment of Anorexia/Cachexia Therapy trial outcome index (ρ?=?0.26). PA was also correlated with fluid retention (ρ = ?0.34) and albumin (ρ?=?0.32), C-reactive protein (ρ = ?0.31), and hemoglobin (ρ?=?0.41) levels. Sub-analysis stratified according to sex revealed that males demonstrated the same results; however, female sex demonstrated a correlation between PA and social well-being (ρ = ?0.43).
Conclusions: PA was correlated with physical condition, but not with psychological well-being. 相似文献
Methods: Forty-nine patients scheduled to undergo open thoracotomy were randomly assigned to receive one of two anesthesia regimens: continuous epidural infusion of ropivacaine and morphine, along with intravenous infusion of ketamine (0.05 mg [middle dot] kg-1 [middle dot] h-1 [approximately 3 mg/h], ketamine group, n = 24) or placebo (saline, control group, n = 25). Epidural analgesia was continued for 2 days after surgery, and infusion of ketamine or placebo was continued for 3 days. Pain was assessed at 6, 12, 24, and 48 h after surgery. Patients were asked about their pain, abnormal sensation on the wound, and inconvenience in daily life at 7 days and 1, 3, and 6 months after surgery.
Results: The visual analog scale scores for pain at rest and on coughing 24 and 48 h after thoracotomy were lower in the ketamine group than in the control group (pain at rest, 9 +/- 11 vs. 25 +/- 20 and 9 +/- 11 vs. 18 +/- 13; pain on coughing, 26 +/- 16 vs. 50 +/- 17 and 30 +/- 18 vs. 43 +/- 18, mean +/- SD; P = 0.002 and P = 0.01, P < 0.0001 and P = 0.02, respectively). The numerical rating scale scores for baseline pain 1 and 3 months after thoracotomy were significantly lower in the ketamine group (0.5 [0-4] vs. 2 [0-5] and 0 [0-5] vs. 1.5 [0-6], median [range], respectively; P = 0.02). Three months after surgery, a higher number of control patients were taking pain medication (2 vs. 9; P = 0.03). 相似文献
Methods: In order to determine the concentrations of melanin and hemoglobin in skin, we used the spectrum resolution (SR) method. In brief, the absorption spectrum of the skin was calculated from the reflection spectrum using a spectrophotometer. The concentrations of melanin and hemoglobin were then determined using a multiple regression analysis, assuming that the absorption spectrum of the skin is expressed as a linear summation of the absorptions of melanin and hemoglobin according to the Lambert–Beer law. The skin changes in the volar forearm, which had been irradiated by ultraviolet rays (UV), were observed daily by the SR method.
Results: A multiple regression analysis with an absorption spectrum of 500–700 nm was performed. The multiple correlation coefficient was 0.993, resulting in a satisfactory precise estimate of the concentrations of melanin. After UV irradiation, the concentration of melanin monitored by the SR method increased until 8 days and decreased gradually afterwards.
Conclusions: The SR method allows the evaluation of the changes of epidermal melanin induced by UV irradiation. 相似文献