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   377篇
  免费   21篇
  国内免费   6篇
耳鼻咽喉   1篇
妇产科学   10篇
基础医学   41篇
口腔科学   8篇
临床医学   35篇
内科学   61篇
神经病学   26篇
特种医学   80篇
外科学   52篇
综合类   5篇
预防医学   14篇
药学   41篇
中国医学   3篇
肿瘤学   27篇
  2023年   2篇
  2022年   2篇
  2021年   8篇
  2020年   1篇
  2019年   8篇
  2018年   10篇
  2017年   6篇
  2016年   6篇
  2015年   9篇
  2014年   11篇
  2013年   22篇
  2012年   35篇
  2011年   60篇
  2010年   15篇
  2009年   14篇
  2008年   24篇
  2007年   39篇
  2006年   27篇
  2005年   31篇
  2004年   17篇
  2003年   18篇
  2002年   8篇
  2001年   2篇
  1999年   5篇
  1998年   3篇
  1997年   2篇
  1996年   1篇
  1991年   3篇
  1989年   1篇
  1988年   1篇
  1986年   1篇
  1958年   1篇
  1957年   1篇
  1956年   3篇
  1955年   3篇
  1954年   4篇
排序方式: 共有404条查询结果,搜索用时 171 毫秒
1.
2.
The main biologically active components of plants belonging to the genus Allium, responsible for their biological activities, including anti-inflammatory, antioxidant and immunomodulatory, are organosulfur compounds. The aim of this study was to synthetize the mixture of dipropyl polysulfides (DPPS) and to test their biological activity in acute hepatitis. C57BL/6 mice were administered orally with DPPS 6 h before intravenous injection of Concanavalin A (ConA). Liver inflammation, necrosis and hepatocytes apoptosis were determined by histological analyses. Cytokines in liver tissue were determined by ELISA, expression of adhesive molecules and enzymes by RT PCR, while liver mononuclear cells were analyzed by flow cytometry. DPPS pretreatment significantly attenuated liver inflammation and injury, as evidenced by biochemical and histopathological observations. In DPPS-pretreated mice, messenger RNA levels of adhesion molecules and NADPH oxidase complex were significantly reduced, while the expression of SOD enzymes was enhanced. DPPS pretreatment decreased protein level of inflammatory cytokines and increased percentage of T regulatory cells in the livers of ConA mice. DPPS showed hepatoprotective effects in ConA-induced hepatitis, characterized by attenuation of inflammation and affection of Th17/Treg balance in favor of T regulatory cells and implicating potential therapeutic usage of DPPS mixture in inflammatory liver diseases.  相似文献   
3.
4.
Introduction: A clinically normal‐appearing nipple in patients with breast cancer may contain unsuspected neoplastic cells. Preservation of a nipple containing occult malignancy could potentially increase local recurrence rates and affect disease‐free survival. Consequently, patients considered for breast conservation operations with nipple preservation must be carefully selected. Methods: Information available on 382 patients diagnosed and treated with breast cancer at the Clinical Center Nis from 2000 to 2003 were retrospectively reviewed. Multivariate hazard analyses was used to assess the association between potential risk factors of cancerous nipple involvement. Results: The frequency of nipple involvement was 12.04%. Nearly half of the patients had disease stage III and IV. Most patients, 29 (63.04%), had a tumor to nipple distance of less then 2 cm. Twenty‐five patients (54.34%) had more then four positive axillary nodes. A central/overlap tumor location was present in 28 (60.87%) patients. Cox multivariate analysis of prognostic factors showed that Stage III (RH 4.79 (1.50–14.68, 1.50–14.72); P= 0.008), central/overlap tumor location (RH 3.28 (0.90–11.20); P= 0.078) and nuclear grade III or greater (RH 2.26 (0.79 to 6.65); P= 0.065) had a statistically significant effect on malign nipple involvement. Conclusions: The multivariable model used in this study showed a significant association between stage, centrally located tumors and nuclear grade III or greater in predicting the risk of cancerous nipple involvement. Preoperative magnetic resonance imaging or computed tomography scan examinations are recommended for treatment planning of breast cancer, in particular nipple preserving surgery in patients with central/overlap tumor localization and with a tumor to nipple distance of less than 2 cm.  相似文献   
5.
Andric N  Ascoli M 《Endocrinology》2008,149(11):5549-5556
We examine the pathways involved in the luteinizing hormone receptor (LHR)-dependent activation of the epidermal growth factor (EGF) network using cocultures of LHR-positive granulosa cells and LHR-negative test cells expressing an EGF receptor (EGFR)-green fluorescent protein fusion protein. Activation of the LHR in granulosa cells results in the release of EGF-like growth factors that are detected by measuring the phosphorylation of the EGFR-green fluorescent protein expressed only in the LHR-negative test cells. Using neutralizing antibodies and real-time PCR, we identified epiregulin as the main EGF-like growth factor produced upon activation of the LHR expressed in immature rat granulosa cells, and we show that exclusive inhibition or activation of the ERK1/2 cascade in granulosa cells prevents or enhances epiregulin release, respectively, with little or no effect on epiregulin expression. These results show that the LHR-stimulated ERK1/2 pathway stimulates epiregulin release.  相似文献   
6.
Objective: To measure fetal and maternal plasma homocysteine (Hcy) concentrations in uncomplicated pregnancies.

Methods: Paired maternal venous and fetal umbilical cord blood (n?=?81) samples were evaluated for plasma Hcy and vitamin B12 levels, in addition to eight neonatal umbilical cord blood samples obtained immediately following delivery.

Results: Both fetal and maternal Hcy concentrations were positively correlated with advancing gestational age (ρ?=?0.44, p?<?0.0001; and ρ?=?0.27, p?<?0.05, respectively). Fetal plasma Hcy concentrations [2.2?µmol/l (IQR: 2.0–3.2)] were significantly lower than both neonatal umbilical vein [5.0?µmol/l (IQR: 4.4–6.5); p?<?0.001] and maternal plasma Hcy levels [4.4?μmo/l (IQR: 3.4–5.4); p?<?0.001]. In addition, Hcy values at term were higher in the umbilical vein compared with the umbilical artery [5.0?μmol/l (IQR: 3.4–5.4) versus 4.2?μmol/l (IQR: 3.7–5.5), respectively; p?=?0.016]. Significant correlation was noted and between fetal and maternal Hcy levels (ρ?=?0.50, p?<?0.0001), while fetal Hcy was negatively correlated with maternal B12 concentrations (ρ?=??0.32, p?<?0.001).

Conclusions: Fetal Hcy levels were significantly lower than maternal and neonatal levels and correlated with gestational age across the second half of pregnancy.  相似文献   

7.
BACKGROUND: Most studies have shown that early post-infarction angina (EPA) implies an unfavorable long-term prognosis among patients with acute myocardial infarction (AMI). However, some studies have failed to establish a link between the occurrence of EPA and increased mortality and recurrent infarction rates. METHODS AND RESULTS: In order to evaluate a long-term prognosis in patients with EPA, we assessed the 5-year prognosis of 80 patients with AMI by the presence or absence of EPA. During the 5-year follow up, the occurrence of death, cardiac death, recurrent infarction, unstable angina, heart failure, revascularization and cardiac events were recorded. A cardiac event was defined as an occurrence of any of the following events: cardiac death, recurrent infarction, unstable angina, heart failure and revascularization. Survival analysis showed no differences between patients with and without EPA in the probability of death (p=NS), cardiac death (p=NS), recurrent myocardial infarction (p=NS) and unstable angina (p=NS). Patients with EPA had a higher probability of developing cardiac events (p=0.0285) and undergoing revascularization procedures (p=0.0188). CONCLUSIONS: EPA increases the risk of patients developing cardiac events and undergoing revascularization procedures, and thereby implies a poor long-term prognosis for patients with AMI.  相似文献   
8.
BACKGROUND/AIMS: Helicobacter pylori elicits a strong local and systemic humoral immune response, but it is not able to eliminate bacteria. Immune response may be important for the course of infection that may lead to different gastroduodenal disease. In order to investigate differences in systemic humoral immune response between patients with different gastroduodenal diseases, we conducted clinical and serological studies. METHODOLOGY: From 1999 to 2001 we enrolled 80 patients with dyspeptic symptoms: 26 with gastritis, 12 with duodenal ulcer, 29 with gastric cancer and 13 with gastric lymphoma. In all patients during diagnostic work-up we performed ELISA test with Helicobacter pylori-specific IgG and IgA. We investigated difference in stimulation of different immunoglobulin classes in patients with different gastroduodenal diseases, particularly benign and malignant. We estimated significance of differences with Mann-Whitney and Fisher exact probability test. RESULTS: All patients enrolled in the study were seropositive. Patients with gastritis had statistically significant higher level of IgG than patients with gastric cancer (p=0.0001), and gastric lymphoma (p=0.006). Patients with duodenal ulcer had statistically significant higher level of IgG than patients with gastric cancer (p=0.02), and gastric lymphoma (p=0.046). IgA level was significantly higher in patients with gastritis than in patients with gastric cancer (p=0.03). IgA>IgG ratio was significantly more frequent in patients with gastric cancer and gastric lymphoma than in patients with gastritis and duodenal ulcer (p=0.0002). CONCLUSIONS: Result of our study suggested that Helicobacter pylori elicits different systemic humoral immune response in patients with gastritis and duodenal ulcer than in patients with gastric cancer and gastric lymphoma at least in intensity of stimulation of different immunoglobulin classes.  相似文献   
9.
10.
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