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   1131篇
  免费   69篇
  国内免费   14篇
耳鼻咽喉   23篇
儿科学   20篇
妇产科学   17篇
基础医学   114篇
口腔科学   51篇
临床医学   123篇
内科学   285篇
皮肤病学   43篇
神经病学   83篇
特种医学   20篇
外科学   177篇
综合类   31篇
预防医学   52篇
眼科学   38篇
药学   88篇
中国医学   9篇
肿瘤学   40篇
  2024年   1篇
  2023年   35篇
  2022年   92篇
  2021年   104篇
  2020年   56篇
  2019年   71篇
  2018年   67篇
  2017年   52篇
  2016年   49篇
  2015年   45篇
  2014年   76篇
  2013年   75篇
  2012年   75篇
  2011年   77篇
  2010年   37篇
  2009年   36篇
  2008年   38篇
  2007年   45篇
  2006年   47篇
  2005年   34篇
  2004年   27篇
  2003年   14篇
  2002年   13篇
  2001年   6篇
  2000年   5篇
  1999年   3篇
  1998年   5篇
  1997年   9篇
  1996年   2篇
  1995年   2篇
  1993年   3篇
  1989年   1篇
  1987年   1篇
  1986年   1篇
  1984年   1篇
  1982年   1篇
  1980年   3篇
  1976年   2篇
  1974年   1篇
  1971年   1篇
  1969年   1篇
排序方式: 共有1214条查询结果,搜索用时 15 毫秒
991.
BACKGROUND: C-phycocyanin, a biliprotein pigment found in some blue green algae (Spirulina platensis) with nutritional and medicinal properties, was investigated for its efficacy on sodium oxalate-induced nephrotoxicity in experimentally induced urolithic rats. METHODS: Male Wistar rats were divided into four groups. Hyperoxaluria was induced in two of these groups by intraperitoneal infusion of sodium oxalate (70 mg/kg), and a pretreatment of phycocyanin (100 mg/kg) as a single oral dosage was given to one of these groups by 1 h prior to sodium oxalate infusion challenges. The study also encompasses an untreated control group and a phycocyanin-alone treated drug control group. The extent of lipid peroxidation (LPO) was evaluated in terms of renal concentrations of MDA, conjugated diene and hydroperoxides. The following assay was performed in the renal tissue (a) antioxidant enzymes such as superoxide dismutase (SOD) and catalase, (b) glutathione metabolizing enzymes such as glutathione peroxidase (GPx), glutathione reductase (GR), glutathione-S-transferase (GST) and glucose 6-phosphate dehydrogenase (G6PD), (c) the low molecular weight antioxidants (GSH, vitamins E and C) and protein carbonyl content. RESULTS: The increased concentrations of MDA, conjugated diene and hydroperoxide (index of the lipid peroxidation) were controlled (P < 0.001) in the phycocyanin-pretreated group. At the outset, the low molecular weight antioxidants were appreciably increased (P < 0.001), whereas the tissue protein carbonyl concentration was decreased (P < 0.001), suggesting that phycocyanin provides protection to renal cell antioxidants. It was noticed that the activities of antioxidant enzymes and glutathione metabolizing enzymes were considerably stabilized in rats pretreated with phycocyanin. CONCLUSION: We suggest that phycocyanin protects the integrity of the renal cell by stabilizing the free radical mediated LPO and protein carbonyl, as well as low molecular weight antioxidants and antioxidant enzymes in renal cells. Thus, the present analysis reveals that the antioxidant nature of C-phycocyanin protects the renal cell against oxalate-induced injury and may be a nephroprotective agent.  相似文献   
992.
Background/aim Magnetic resonance (MR) images, signal intensity ratios calculated using region of interests (ROI) in T2W images by proportioning the dominant myoma to iliac muscle can aid patient selection and, thus, in achieving better outcomes with the uterine artery embolization (UAE) procedure. The present study investigates the association between the success of UAE treatment with signal intensity (SI) ratio of the dominant myoma to the iliac muscle in MR imaging performed prior to the procedure.Materials and methods This is a retrospective study and included 30 patients who admitted to our clinic between February 2017 and July 2019 due to symptoms associated with myoma and who underwent MR imaging before and after UAE treatment. All patients, MR images obtained before UAE treatment and at the 12th month after the procedure were evaluated. In MRI, SI values were calculated by proportioning the dominant myoma to the iliac muscle using circular ROI in T1 weighted (W), T2W, and post-contrast T1W images. In the present study, 50% or more volumetric regression of the myoma with infarction of fibroids (loss of enhancement) at the 12-month follow-up MRI after the procedure was considered a successful procedure. Results Myoma volumes calculated in MR images showed significant differences between the MRI performed before UAE procedure and the MRI performed at the 12th month after the procedure (p < 0.0001). SI ratio calculated from pre-procedure T2W MR images was found to be a significant determinant of 50% or more volumetric regression in the myoma after UAE procedure (p = 0.017), T1W, post-contrast T1W images were not statistically significant (p = 0.211).Conclusion Our results indicate that SI ratio of the dominant myoma to the iliac muscle calculated using ROI in T2W images of MR studies performed before UAE procedure can predict the success of the procedure.  相似文献   
993.

Background

Different medical therapies are employed in acute lung injury (ALI) but there is still a debate about the efficacy of these drugs. Among these therapies steroids are clinically applied and bosentan is experimentally studied. The aim of this study was to evaluate the efficacy of these two drugs to treat inflammation in ALI by histopathological comparison.

Methods

The five experimental groups (n = 5 per group) were: saline control (Group I); lipopolysaccharide (LPS) + saline (Group II); LPS + dexamethasone (Group III); LPS + 50 mg/kg bosentan (Group IV); and LPS + 100 mg/kg bosentan (Group V). Bosentan was administered orally one hour before and 12 hours after LPS treatment. Dexamethasone was administered intraperitoneally in three doses of 1 mg/kg; one dose was co-administered with LPS and the other two doses were given respectively 30 minutes before and after LPS treatment. Vasodilation-congestion, hemorrhage, polymorphonuclear leukocyte (PMN) infiltration, mononuclear leukocyte (MNL) infiltration, alveolar wall thickening, alveolar destruction/emphysematous appearance, and focal organization were the parameters used as criteria for evaluating inflammation and efficacy of treatment.

Results

Compared to the LPS-only group (Group II), dexamethasone treatment (Group III) resulted in significant improvements in vasodilation-congestion, hemorrhage, PMN and MNL infiltration, alveolar wall thickening and emphysematous areas. Treatment with 50 mg/kg dose of bosentan (Group IV) also resulted in significant improvements in hemorrhage, PMN and MNL infiltration, alveolar wall thickening and alveolar destruction. Reducing lung injury and reparative effects of 100 mg/kg bosentan were significant in all parameters.

Conclusions

Bosentan is as effective as dexamethasone for treating lung injury in ALI. Bosentan at 100 mg/kg can be recommended as a first treatment choice based on its significant reducing lung injury and reparative effects.
  相似文献   
994.
Methyl and ethyl alcohol poisoning are still responsible for high morbidity and mortality rates. The purpose of this retrospective study was to examine ethyl and methyl alcohol poisoning related deaths in Ankara and surrounding cities between 2001 and 2011 and compare them with previous studied conducted in Turkey and other countries. For this purpose, 10,720 medico-legal autopsy cases performed in Ankara Branch of the Council of Forensic Medicine were reviewed in terms of alcohol poisonings.The deaths due to methanol and ethanol poisoning were 74 (0.69% of all medico-legal autopsies performed) and the distribution among them was 35 (47.3%) for methanol poisoning and 39 (52.7%) for ethanol poisoning. Overwhelming majority of the cases were male (n = 67, 90.5%). The mean age of the victims was 44.9 ± 10.9 years and ranging from 21 to 92 years. The age group of 35–49 years was the mostly affected. Most of the cases were seen in 2004 (n = 12, 16.2%). The levels of postmortem blood alcohol levels were available for all cases and the mean alcohol levels were 322.8 ± 155.5 mg/dL ranging from 74 to 602 mg/dL for methanol and 396.8 ± 87.1 mg/dL and ranging from 136 to 608 mg/dL for ethanol.Early diagnosis is essential for successful treatment in methanol and ethanol poisoning. Besides increased awareness, more sensitive/specific diagnostic tools, and the prompt approach to the poisoned individual should be implemented in the hospitals.  相似文献   
995.
ObjectiveEpithelial ovarian neoplasms are extremely uncommon in children. Ovarian mucinous cystadenoma is benign and an extremely rare presentation in the premenarchal period. We present a case of giant mucinous cystadenoma of the left ovary in a 13-year-old and a review of the supporting literature.Case ReportThe patient was admitted with a history of increasing abdominal distension and pain for approximately 3 months and a history of an ovarian mass for 3 years. An adnexal mass measuring 40 × 30 × 20 cm was detected by abdominal ultrasonography and computed tomography. The tumor markers CEA, CA 19-9, and CA-125 were elevated, although α-fetoprotein and human chorionic antigen levels were within the normal range. The patient underwent surgery. The smooth-surfaced mass filled the abdomen. A frozen section biopsy was performed, and the results indicated a benign mucinous cystadenoma. A unilateral oophorectomy with tumor removal was performed.ConclusionThe ovarian mass was revealed by abdominal distension, and a diagnosis was established by frozen biopsy. Complete and careful surgical resection provides satisfactory results; however, careful follow-up is required.  相似文献   
996.
997.
998.
999.
1000.
Objectives:To detect the cotinine and nicotine serum concentrations of female and male C57BL/6J mice after a 4-week exposure to electronic (e)-cigarette vapors using ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS).Methods:This experimental study was carried out at an animal facility and laboratories, College of Pharmacy, King Saud University, Riyadh, Saudi Arabia, between January and August 2020. A 4-week exposure to e-cigarettes was carried out using male and female mice and serum samples were obtained for cotinine and nicotine quantification using UPLC-MS/MS. The chromatographic procedures involved the use of a BEH HSS T3 C18 column (100 mm x 2.1 mm, 1.7 μm) with acetonitrile as a mobile phase and 0.1% formic acid (2:98 v/v).Results:The applied methodology has highly efficient properties of detection, estimation, and extraction, where the limit of quantification (LOQ) for nicotine was 0.57 ng/mL and limit of detection (LOD) for nicotine was 0.19 ng/mL, while the LOQ for cotinine was 1.11 ng/mL and LOD for cotinine was 0.38 ng/mL. The correlation coefficient was r2>0.99 for both compounds. The average recovery rate was 101.6±1.33 for nicotine and 100.4±0.54 for cotinine, while the precision and accuracy for cotinine and nicotine were less than 6.1. The serum cotinine level was higher in males (433.7±19.55) than females (362.3±16.27).Conclusion:This study showed that the gender factor might play a crucial role in nicotine metabolism.  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