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   13000篇
  免费   509篇
  国内免费   69篇
耳鼻咽喉   168篇
儿科学   432篇
妇产科学   408篇
基础医学   1162篇
口腔科学   390篇
临床医学   1112篇
内科学   2783篇
皮肤病学   209篇
神经病学   607篇
特种医学   411篇
外科学   2365篇
综合类   388篇
现状与发展   1篇
一般理论   13篇
预防医学   770篇
眼科学   292篇
药学   1166篇
中国医学   94篇
肿瘤学   807篇
  2024年   120篇
  2023年   146篇
  2022年   379篇
  2021年   594篇
  2020年   342篇
  2019年   428篇
  2018年   507篇
  2017年   315篇
  2016年   399篇
  2015年   412篇
  2014年   557篇
  2013年   734篇
  2012年   978篇
  2011年   942篇
  2010年   541篇
  2009年   411篇
  2008年   680篇
  2007年   758篇
  2006年   677篇
  2005年   608篇
  2004年   537篇
  2003年   464篇
  2002年   444篇
  2001年   150篇
  2000年   127篇
  1999年   127篇
  1998年   72篇
  1997年   60篇
  1996年   56篇
  1995年   40篇
  1994年   49篇
  1993年   34篇
  1992年   94篇
  1991年   56篇
  1990年   70篇
  1989年   62篇
  1988年   47篇
  1987年   50篇
  1986年   31篇
  1985年   43篇
  1984年   29篇
  1983年   38篇
  1982年   21篇
  1980年   20篇
  1979年   34篇
  1978年   20篇
  1977年   26篇
  1974年   36篇
  1973年   34篇
  1972年   23篇
排序方式: 共有10000条查询结果,搜索用时 125 毫秒
81.

Background and Aim:

Ischemia/reperfusion (I/R) injury in the liver occurs after a prolonged period of ischemia followed by restoration of hepatic blood perfusion. During the surgery of abdominal aorta, I/R injury causes damage to lower extremities and many organs, especially liver. The antioxidant and tumor necrosis factor-alpha (TNF-α) suppression effects of topiramate (TPM) have been reported in several studies. We evaluated the potential protective effect of TPM on cellular damage in liver tissue during I/R injury.

Materials and Methods:

Thirty male Wistar albino rats were divided into three groups: Control, I/R, and I/R plus TPM (I/R + TPM) groups. Laparotomy without I/R injury was performed in the control group. After laparotomy, cross-ligation of infrarenal abdominal aorta was applied for 2 h in I/R groups that was followed by 2 h of reperfusion. TPM (100 mg/kg/day) was orally administrated to the animals in the I/R + TPM group for seven consecutive days before I/R procedure.

Results:

The I/R group''s TNF-α and interleukin-6 (IL-6) levels were significantly higher than those of the control (P = 0.010; P = 0.002) and I/R + TPM groups (P = 0.010; P = 0.002, respectively). Asymmetric dimethyl arginine (ADMA) levels of I/R group were higher than the control (P = 0.015) and I/R + TPM groups. I/R caused serious histopathological damage to liver tissue; however, TPM led to very low histopathological changes.

Conclusion:

Our data demonstrated that TPM treatment prominently decreases the severity of liver I/R injury. TPM pretreatment may have preventive effects on liver injury via I/R during intra-abdominal surgery.  相似文献   
82.

Ethnopharmacological relevance

The fruit hull of Garcinia mangostana Linn. has been used in traditional medicine for treatment of various inflammatory diseases. Hence, this study aims to investigate the in vitro and in vivo anti-inflammatory effect of β mangostin (βM), a major compound present in Garcinia mangostana.

Materials and methods

The in silico analysis of inflammatory mediators such as cyclooxygenase (COX) and nuclear factor-kappa B (NF-kB) were performed via molecular docking. Further evaluation of anti-inflammatory effect was conducted in lipopolysaccharide (LPS) induced RAW 264.7 macrophages. Suppression of activated NF-kB was analyzed by high content screening. βM triggered inhibition of COX-1 and COX-2 in vitro were studied using biochemical kit. The in vivo model used in this study was carrageenan-induced peritonitis model, where reduction in carrageenan-induced peritonitis is measured by leukocyte migration and vascular permeability. In addition, the evaluation of βM?s effect on carrageenan induced TNF-α and IL-1β release on peritoneal fluid was also carried out.

Results

Treatment with βM could inhibit the LPS-induced NO production but not the viability of RAW 264.7. Similarly, βM inhibited PGE2 production and the cytokines: TNF-α and IL-6. The COX catalyzed prostaglandin biosynthesis assay had showed selective COX-2 inhibition with a 53.0±6.01% inhibition at 20 µg/ml. Apart from this, βM was capable in repressing translocation of NF-kB into the nucleus. These results were concurrent with molecular docking which revealed COX-2 selectivity and NF-kB inhibition. The in vivo analysis showed that after four hours of peritonitis, βM was unable to reduce vascular permeability, yet could decrease the total leukocyte migration; particularly, neutrophils. Meanwhile, dexamethasone 0.5 mg/kg, successfully reduced vascular permeability. The levels of TNF-α and IL-1β in peritoneal fluid was reduced significantly by βM treatment.

Conclusion

The current study supports the traditional use of Garcinia mangostana fruit hull for treatment of inflammatory conditions. In addition, it is clear that the anti-inflammatory efficacy of this plant is not limited to the presence of α and γ, but β also with significant activity.  相似文献   
83.
    

Ethnopharmacological relevance

African trypanosomiasis is one of the neglected tropical diseases caused by different species of trypanosomes that affect both human and livestock with devastating consequences in the continent. Most of the affected populations commonly use traditional medicinal plants for the treatment of the disease. Consequently, this prompted ethnopharmacological research activities on the anti-trypanosomal activity of a number of these African medicinal plants in order to validate their ethnomedicinal use. Furthermore, such studies could lead to the identification of chemical leads for the development of newer anti-trypanosomal agents from those plants. This review aims to provide updated information on the ethnopharmacological evidence of African medicinal plants with anti-trypanosomal activity.

Methods

Literature was collected via electronic search (PubMed, Sciencedirect, Medline and Google Scholar) from published articles that report on the in vitro or in vivo anti-trypanosomal activity of plants that were collected from different parts of Africa.

Results

African medicinal plants investigated for in vitro and in vivo anti-trypanosomal activity from January 1993 to October 2013 are systematically compiled and all the in vivo studies are critically discussed. A total of 264 plant species belonging to 79 families were investigated for anti-trypanosomal activity. However, only 48 bioactive anti-trypanosomal compounds were successfully isolated in pure forms. Furthermore, some of the plants were investigated for possible ameliorative effects on the trypanosome-induced pathological changes out of which 18 plants were reported to be effective while a few others were not. In spite of interesting preclinical ethnopharmacological evidence for anti-trypanosomal activity, not a single African medicinal plant was investigated in a clinical study.

Conclusion

Several African medicinal plants have demonstrated promising anti-trypanosomal effects but the studies on the anti-trypanosomal potentials of these plants are not taken beyond proof of concept stage. It is hoped that the article would stimulate future clinical studies because of the paucity of knowledge in this area.  相似文献   
84.

Ethnopharmacological relevance

Khaya senegalensis A. Juss (Meliaceae) is commonly exploited for the traditional treatment of diabetes mellitus in Nigeria and Togo. The present study was conducted to examine the anti-diabetic activity of Khaya senegalensis butanol fraction (KSBF) of root ethanolic extract in a type 2 diabetes (T2D) model of rats.

Materials and methods

T2D was induced in rats by feeding a 10% fructose solution ad libitum for two weeks followed by a single intraperitoneal injection of streptozotocin (40 mg/kg body weight) and the animals were treated with 150 and 300 mg/kg body weight (BW) of the fraction for five days in a week. Relevant diabetes-related parameters were analyzed in all experimental animals.

Results

The KSBF treatment, at 300 mg/kg BW, significantly (p<0.05) reduced blood glucose level, improved oral glucose tolerance ability and β-cell function (HOMA-β), decreased insulin resistance (HOMA-IR), stimulated hepatic glycogen synthesis, ameliorated serum lipids alterations and prevented hepatic and renal damages compared to untreated diabetic rats. Additionally, the fraction insignificantly (p>0.05) improved weight gain, decreased food and fluid intake, stimulated insulin secretion and lowered serum fructosamine concentrations compared to untreated diabetic rats.

Conclusions

Data from this study suggests that orally administered KSBF, at 300 mg/kg BW, possess remarkable anti-type 2 diabetic activity and could ameliorate some diabetes-associated complications and hence can be considered as a source of potential anti-type 2 diabetic medicine.  相似文献   
85.
ObjectiveRecent studies have suggested that nuts have favorable effects beyond lipid lowering. We aimed to investigate effect of the Antep pistachio (Pistacia vera L.) on blood glucose, lipid parameters, endothelial function, inflammation, and oxidation in healthy young men living in a controlled environment.MethodsA Mediterranean diet was administered to normolipidemic 32 healthy young men (mean age 22 y, range 21–24) for 4 wk. After 4 wk, participants continued to receive the Mediterranean diet but pistachio was added for 4 wk by replacing the monounsaturated fat content constituting ≈20% of daily caloric intake. Fasting blood samples and brachial endothelial function measurements were performed at baseline and after each diet.ResultsCompared with the Mediterranean diet, the pistachio diet decreased glucose (P < 0.001, ?8.8 ± 8.5%), low-density lipoprotein (P < 0.001, ?23.2 ± 11.9%), total cholesterol (P < 0.001, ?21.2 ± 9.9%), and triacylglycerol (P = 0.008, ?13.8 ± 33.8%) significantly and high-density lipoprotein (P = 0.069, ?3.1 ± 11.7%) non-significantly. Total cholesterol/high-density lipoprotein and low-density lipoprotein/high-density lipoprotein ratios decreased significantly (P < 0.001 for both). The pistachio diet significantly improved endothelium-dependent vasodilation (P = 0.002, 30% relative increase), decreased serum interleukin-6, total oxidant status, lipid hydroperoxide, and malondialdehyde and increased superoxide dismutase (P < 0.001 for all), whereas there was no significant change in C-reactive protein and tumor necrosis factor-α levels.ConclusionIn this trial, we demonstrated that a pistachio diet improved blood glucose level, endothelial function, and some indices of inflammation and oxidative status in healthy young men. These findings are in accordance with the idea that nuts, in particular pistachio nuts, have favorable effects beyond lipid lowering that deserve to be evaluated with prospective follow-up studies.  相似文献   
86.
Allogeneic hematopoietic cell transplantation (HCT) has been shown to restore normal hematopoiesis in patients with Fanconi anemia (FA), with excellent results in matched related donor HCT. Outcomes of alternative donor HCT are less favorable, however. In patients without FA, several reports have documented stable engraftment and/or a low risk of graft-versus-host disease (GVHD) using unmanipulated HLA-mismatched related donors and post-HCT cyclophosphamide (PT-CY) for GVHD prophylaxis. Data on the use of this approach in patients with FA are scarce, and thus we launched a study of HLA-mismatched related donor HCT in these patient. Here we report our findings in 19 patients. The conditioning was fludarabine 30 mg/m2/day for 5 days, antithymocyte globulin 5 mg/kg/day for 4 days, and total body irradiation (total dose, 200 cGy). GVHD prophylaxis was cyclosporine and mycophenolate and reduced doses of PT-CY, 25 mg/kg, on days +3 and +5. All patients exhibited absolute neutrophil count recovery. Grade III-IV acute GVHD occurred in 3 patients, and chronic GVHD occurred in 1 patient. At a mean follow-up of 38.3 ± 5.8 months, the 5-year probability of overall survival for our patients was 89.2% ± 7.2%. The regimen was well tolerated; hemorrhagic cystitis occurred in 7 patients, and severe mucositis occurred in 5 patients. There were 2 deaths; the primary cause of death was severe GVHD in 1 patient and leukemia recurrence in the other. We conclude that in patients with FA lacking a matched related donor, the use of mismatched related HCT with low-dose PT-CY is a viable option; it is well tolerated, with a high rate of engraftment and an acceptable incidence of GVHD.  相似文献   
87.

Purpose

Triple (ER-, PR-, HER2-) negative breast carcinoma lack targeted therapies, making this group of tumors difficult to treat. By definition, the lack of HER2 expression means a case scoring 0 or 1+ after immunophenotypical analysis and makes the patients avoiding therapeutical chances with anti-HER2 inhibitors. We sought to recruit from a group of triple negative breast carcinoma, patients eligible for effective personalized targeted therapy with anti-HER therapies on the basis of their HER2 gene status.

Methods

135 patients diagnosed with IHC triple negative breast carcinoma were studied. Whole tissue sections were used for in situ hybridization analysis.

Results

8/100 (8 %) of ductal-type triple negative breast carcinoma presented Her-2/neu gene amplification versus 2/35 (5.7 %) non-ductal triple negative breast carcinoma. Three cases showed a ratio 2.5. One case showed Her-2/neu heterogeneous gene amplification, ratio 2.3. The other six showed from 7 to 8 absolute Her-2/neu gene copy number. Two cases staged pT1c, and eight cases staged pT2. Eight cases graded G3 and two cases G2.

Conclusion

(1) Eight percentage of ductal and 5.7 % non-ductal-type triple negative breast carcinoma present Her-2/neu gene amplification, (2) the standard diagnostic flowchart “do not FISH in 0–1+ (HER2-) breast carcinoma” should be replaced by “do FISH in triple (ER-, PR-, HER2-) negative breast carcinoma,” to avoid loss of therapeutical chances in a cohort of such a patients, (3) we demonstrated the identification of a small but significant subset of patients targetable with anti-HER2 inhibitors, giving patients affected by (ex)triple negative breast carcinoma new personalized therapeutical chances.  相似文献   
88.
Pulmonary arterial hypertension (PAH) is a progressive and a life-threatening disease with its high morbidity and mortality ratios. On searching for new shining targets in pathogenesis, we noticed, in our previous studies, urotensin-II (UII) in systemic sclerosis with potent angiogenic and pro-fibrotic features. Owing to the mimicking properties of UII with endothelin-1 (ET1), we attempted to investigate the effect of palosuran in a PAH rat model. Thirty rats were randomly divided into three groups, with each group comprising 10 rats: group 1 (control group) received the vehicle subcutaneously, instead of monocrotaline (MCT) and vehicle; group 2 (MCT group) received subcutaneous MCT and vehicle; and group 3 (MCT + palosuran group) received subcutaneous MCT and palosuran. Serum UII, ET1, transforming growth factor-β1 (TGF-β1) levels, pulmonary arteriolar pathology of different diameter vessels, and cardiac indices were evaluated. The ET1, TGF-β1, and UII levels were significantly diminished in the treatment group, similar to the controls (p?<?0.001). Right ventricular hypertrophy index and mean pulmonary arterial pressure scores were also significantly reduced in the treatment group (p?=?0.001). Finally, in the 50–125-μm diameter arterioles, in contrast to Groups 3 and 1, there was a statistically significant thickness (p?<?0.01) in the arteriolar walls of rats in Group 2. The treatment effect on arteries of more than 125-μm diameters was found to be valuable but not significant. Owing to its healing effect on hemodynamic, histological, and biochemical parameters of MCT-induced PAH, palosuran as an antagonist of UII might be an optional treatment alternative for PAH.  相似文献   
89.
90.

Background

Two-dimensional (2D) speckle-tracking strain imaging is a novel method for assessment of regional myocardial deformation that uses tracking of acoustic speckles or kernels rather than Doppler myocardial velocities. It has been suggested that Left atrial (LA) strain as measured by 2D speckle tracking can be used to evaluate dynamic LA function.

Objective

To study the relation between left atrial deformation and the severity of coronary artery stenosis in patients with stable coronary artery disease (CAD).

Study design

30 patients with stable coronary artery disease (SCAD) with coronary artery stenosis (>50%) who were admitted for elective coronary angiography at Ain Shams University hospitals and AlAzhar University hospitals were included in the study. Measurements of conventional echocardiographic parameters as well as LA strain and strain rate parameters were obtained, Syntax (SX) score was calculated for all patients.

Results

Patients were categorized into 3 groups: low Syntax score of <23 (Group I), moderate syntax score 23–32 (Group II) and high syntax score of ≥33 (Group III). Peak atrial longitudinal strain (PALS) (Group I: 29.80?±?4.48, Group II: 22.44?±?1.42, Group III: 19.53?±?4.46; p?<?0.001) and Peak atrial contraction strain (PACS) (Group I: 13.43?±?4.05, Group II: 10.84?±?2.47, Group III: 7.19?±?0.71; p?<?0.022) were significantly lower in high syntax group. Significant negative correlation was found between SX score level and LA strain parameters (PALS and PACS) (r?=?0.861; p?<?0.001).

Conclusion

Left atrial deformation analysis by 2D Speckle tracking Doppler Echocardiography can predict the severity of coronary affection in patients with stable CAD.  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