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   5683篇
  免费   272篇
  国内免费   33篇
耳鼻咽喉   110篇
儿科学   267篇
妇产科学   129篇
基础医学   473篇
口腔科学   234篇
临床医学   508篇
内科学   1319篇
皮肤病学   103篇
神经病学   277篇
特种医学   116篇
外科学   924篇
综合类   349篇
一般理论   4篇
预防医学   359篇
眼科学   186篇
药学   388篇
中国医学   32篇
肿瘤学   210篇
  2024年   4篇
  2023年   86篇
  2022年   279篇
  2021年   396篇
  2020年   183篇
  2019年   200篇
  2018年   227篇
  2017年   152篇
  2016年   186篇
  2015年   245篇
  2014年   284篇
  2013年   289篇
  2012年   427篇
  2011年   399篇
  2010年   232篇
  2009年   195篇
  2008年   304篇
  2007年   292篇
  2006年   300篇
  2005年   281篇
  2004年   227篇
  2003年   214篇
  2002年   171篇
  2001年   46篇
  2000年   49篇
  1999年   35篇
  1998年   28篇
  1997年   18篇
  1996年   21篇
  1995年   13篇
  1994年   15篇
  1993年   7篇
  1992年   23篇
  1991年   20篇
  1990年   19篇
  1989年   13篇
  1988年   14篇
  1987年   13篇
  1986年   5篇
  1985年   10篇
  1984年   5篇
  1983年   6篇
  1980年   5篇
  1979年   5篇
  1977年   5篇
  1974年   6篇
  1973年   4篇
  1972年   4篇
  1970年   5篇
  1969年   4篇
排序方式: 共有5988条查询结果,搜索用时 62 毫秒
61.
激素敏感脂酶基因高度表达对泡沫细胞形成的作用   总被引:3,自引:0,他引:3  
中国仓鼠卵细胞在给予β-VLDL后,细胞内蓄积胆固醇酯,形成泡沫样细胞。以腺病毒基因转移方法书激素敏感脂酶基因转染到中国仓鼠卵细胞中,得到了来自激素敏感脂酶的胆固醇酯水解活性高度表达,此时,β-VLDL导致的胆固醇酯蓄积作用被阻断,提示增加胆固醇酯水解可以防止泡沫细胞形成。  相似文献   
62.
It has been commonly recognized that circadian rhythm and sleep/wake cycle are causally involved in bipolar disorder. There has been a paucity of systematic research considering the relations between sleep and mood states in bipolar disorder. The current study examines the possible influences of sleep deprivation on mood states and endocrine functions among first-degree relatives of patients with bipolar disorder and healthy controls. Blood samples were taken at two time points in the consecutive mornings at predeprivation and postdeprivation periods. Participants simultaneously completed the Profiles of Mood States at two time points after giving blood samples. Plasma T3 and TSH levels increased after total sleep deprivation in both groups. Sleep deprivation induced TSH levels were reversely associated with depression–dejection among healthy controls. A paradoxical effect was detected for only the first-degree relatives of the patients that changes in plasma cortisol levels negatively linked to depression–dejection and anger–hostility scores after total sleep deprivation. Plasma DHEA levels became correlated with vigor-activity scores after sleep deprivation among first-degree relatives of bipolar patients. On the contrary, significant associations of depression–dejection, anger–hostility, and confusion–bewilderment with the baseline plasma DHEA levels became statistically trivial in the postdeprivation period. Findings suggested that first-degree relatives of patients with bipolar disorder had completely distinct characteristics with respect to sleep deprivation induced responses in terms of associations between endocrine functions and mood states as compared to individuals whose relatives had no psychiatric problems. Considering the relationships between endocrine functions and mood states among relatives of the patients, it appears like sleep deprivation changes the receptor sensitivity which probably plays a pivotal role on mood outcomes among the first-degree relatives of patients with bipolar disorder.  相似文献   
63.
The self-renewal versus differentiation choice of Drosophila and mammalian neural stem cells (NSCs) requires Notch (N) signaling. How N regulates NSC behavior is not well understood. Here we show that canonical N signaling cooperates with a noncanonical N signaling pathway to mediate N-directed NSC regulation. In the noncanonical pathway, N interacts with PTEN-induced kinase 1 (PINK1) to influence mitochondrial function, activating mechanistic target of rapamycin complex 2 (mTORC2)/AKT signaling. Importantly, attenuating noncanonical N signaling preferentially impaired the maintenance of Drosophila and human cancer stem cell-like tumor-forming cells. Our results emphasize the importance of mitochondria to N and NSC biology, with important implications for diseases associated with aberrant N signaling.  相似文献   
64.
65.
Clinical Oral Investigations - 3D cephalometric analysis performed on cone-beam or multi-slice computed tomography (CBCT, MSCT) has superior diagnostic value compared to 2D cephalometry based on...  相似文献   
66.
BackgroundThe coronavirus diseases of 2019 (COVID-19) pandemic was classified as one of the worst pandemics in the 21st century. Its rapid transmission, unpredicted mortality rate, and the uncertainty surrounding its transmission method have evoked additional fear and anxiety. Nonetheless, to the best of our knowledge, no prior study has explored PTSD prevalence three months after the start of the quarantine procedures in Saudi Arabia nor has examined PTSD prevalence by three different methods.ObjectiveThis observational cross-sectional study aimed to identify the prevalence, severity, and influencing factors of PTSD in different regions of Saudi Arabia three months after the onset of the quarantine procedures related to the COVID-19 pandemic.MethodsThrough the month of June 2020, 1374 people (49.05% men and 50.95% women) completed a 35-item, 10-minute online. The prevalence of PTSD was measured using PCL-S (specific for COVID-19) that assesses the 17 symptoms of PTSD. Resilience was measured using 2-items Arabic version of the Connor-Davidson Resilience Scale 2 (CD-RISC 2).ResultsWe calculated the prevalence by three methods, namely, PTSD cut-off score, criteria, and combined, and the prevalence was 22.63%, 24.8%, and 19.6%, respectively. Female participants showed higher prevalence than male. As well, participants who were either tested positive or suspected of having been infected with COVID-19 showed higher PTSD prevalence. Higher resilience was associated with lower PTSD prevalence.ConclusionsThis was the first study to report PTSD prevalence by three differential methods three months after the onset of the quarantine procedures related to the COVID-19 pandemic in Saudi Arabia. We observed a significant impact of the COVID-19 pandemic in the Saudi population; therefore, great attention should be performed in implementing new procedures that deal with the highlighted risk factors, especially in vulnerable groups, to overcome the psychological impact of the COVID-19 pandemic.  相似文献   
67.
In this study, we aimed to compare the effects of dexpanthenol and N-acetylcysteine on wound healing. The wound healing process is a multifaceted sequence of activities associated with tissue restoration process. A number of investigations and clinical studies have been performed to determine new approaches for the improvement of wound healing. A total of 30 rats were divided into 3 equal groups. A linear 2-cm incision was made in the rats'' skin. No treatment was administered in the first (control) group. Dexpanthenol cream was administered to the rats in the second group and 3% N-acetylcysteine cream was administered to the rats in the third group. The wound areas of all of the rats were measured on certain days. On the 21st day, all wounds were excised and histologically evaluated. The epithelialization and granulation rates between the groups were revealed to be similar in microscopic evaluations. Although the fibrosis was remarkable in the control group as compared with the other groups, it was similar in N-acetylcysteine and dexpanthenol groups. Angiogenesis rate was remarkable in the N-acetylcysteine group compared with the others. In multiple-comparison analysis, Dexpanthenol and N-acetylcysteine groups had similar results in terms of wound healing rates (P < 0.05), which were both higher than in the control group (P > 0.05). The efficacy of N-acetylcysteine in wound healing is comparable to dexpanthenol, and both substances can be used to improve wound healing.Key words: N-acetylcysteine, Dexpanthenol, Wound healingWound healing is a multifaceted sequence of activities associated with the tissue restoration process.1 This activity takes place in 4 main steps: inflammation, proliferation, matrix deposition, and remodeling.2,3 Moreover, there are many factors that might have harmful effects on the wound healing process. In this regard, there have been numerous analyses and clinical studies aiming to find new methods for the improvement of wound healing processes.4Dexpanthenol is the biologically-active alcohol of pantothenic acid, which leads to an elevation in the amount of coenzyme A in the cell. Dexpanthenol is extensively used in topical form, since it can easily penetrate the skin even at large local concentrations. When used in formulations, dexpanthenol is most effective for the stimulation of epithelialization, granulation, and the mitigation of itching.5N-acetylcysteine (NAC) is a prodrug that supplies bioavailable cysteine for glutathione replenishment and prevents oxidative damage as well as inflammation. It also leads to glutathione (GSH) formation in the body. Besides fostering angiogenesis, it is used to scavenge free radicals. NAC has a number of functions in the stages of repair process, including cell proliferation, migration, and scratch wound healing. Moreover, NAC has also been reported to promote wound healing in diabetic rats.6In this study, we aimed to compare the effects of dexpanthenol, a molecule that is widely used to improve wound healing, and NAC, a molecule that reduces oxidative stress and inflammation, on wound healing.  相似文献   
68.
69.
70.
Hydatid cyst disease, which is endemically observed and an important health problem in our country, involves the spleen at a frequency ranking third following the liver and the lungs. In this study, we aimed to evaluate the efficacy and results of management in splenic hydatid cysts. The demographic data, localization, diagnosis, treatment methods, and the length of postoperative hospital stay of patients with splenic hydatid cysts in a 12-year period were evaluated retrospectively. Seventeen cases were evaluated. Among these, 13 were females and four were males. Seven had solitary splenic involvement, eight had involvement of both the spleen and the liver, and two had multiple organ involvement. Ten had undergone splenectomy, one had undergone distal splenectomy, and the remaining cases had undergone different surgical procedures. The patients had received albendazole treatment in the pre- and postoperative period. One patient had died secondary to hypernatremia on the first postoperative day. The clinical picture in splenic hydatid cysts, which is seen rarely, is usually asymptomatic. The diagnosis is established by ultrasonography and abdominal CT. Although splenectomy is the standard mode of treatment, spleen-preserving methods may be used.  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