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   879篇
  免费   59篇
  国内免费   5篇
耳鼻咽喉   15篇
儿科学   18篇
妇产科学   31篇
基础医学   114篇
口腔科学   88篇
临床医学   68篇
内科学   131篇
皮肤病学   13篇
神经病学   54篇
特种医学   28篇
外科学   63篇
综合类   49篇
一般理论   1篇
预防医学   115篇
眼科学   27篇
药学   75篇
中国医学   8篇
肿瘤学   45篇
  2023年   8篇
  2022年   26篇
  2021年   55篇
  2020年   32篇
  2019年   35篇
  2018年   60篇
  2017年   25篇
  2016年   28篇
  2015年   30篇
  2014年   32篇
  2013年   50篇
  2012年   62篇
  2011年   69篇
  2010年   47篇
  2009年   19篇
  2008年   40篇
  2007年   34篇
  2006年   34篇
  2005年   34篇
  2004年   27篇
  2003年   20篇
  2002年   21篇
  2001年   11篇
  2000年   15篇
  1999年   16篇
  1998年   5篇
  1997年   2篇
  1994年   1篇
  1992年   2篇
  1991年   11篇
  1990年   9篇
  1989年   12篇
  1988年   10篇
  1987年   7篇
  1986年   8篇
  1985年   3篇
  1984年   2篇
  1983年   8篇
  1982年   1篇
  1981年   2篇
  1979年   4篇
  1978年   7篇
  1977年   1篇
  1975年   6篇
  1974年   1篇
  1973年   2篇
  1972年   3篇
  1971年   2篇
  1970年   1篇
  1968年   1篇
排序方式: 共有943条查询结果,搜索用时 15 毫秒
91.
92.
Bovine tooth enamel with a low and uniform fluorine content was used for the study of fluorine uptake by the Micro-Acid-Drop enamel biopsy technique from different treatment agents commonly used in Sweden. The fluorine concentration in the enamel was also measured after an exposure of the treated test surfaces in artificial saliva for 90 minutes. Sodium fluoride 0.2% and 2%, ferric aluminum fluoride solution and Duraphat varnish showed a high uptake of fluorine in the enamel with the highest concentration in the surface layer. Fluor Protector and the toothpastes showed a considerably lower fluorine uptake. After immersion in artificial saliva of the specimens, the concentration of fluorine in the enamel decreased.  相似文献   
93.

Background

In the fight against malaria caused by Plasmodium falciparum, the successes achieved by artemisinin were endangered by resistance of the parasites to the drug. Whole genome sequencing approach on artemisinin resistant parasite line discovered k13 gene associated with drug resistance. In vitro and in vivo studies indicated mutations in the k13 gene were linked to the artemisinin resistance.

Methodology

The literatures published after April, 2015 up to December, 2016 on k13 mutant alleles for artemisinin resistance in Plasmodium falciparum and relevant literatures were comprehensively reviewed.

Results

To date, 13 non-synonymous mutations of k13 gene have been observed to have slow parasite clearance. Worldwide mapping of k13 mutant alleles have shown mutants associated with artemisinin resistance were confined to southeast Asia and China and did not invade to African countries. Although in vitro ring stage survival assay of 0–3 h was a recently developed assay, it was useful for rapid detection of artemisinin resistance associated k13 allelic marker in the parasite. Recently, dissemination of k13 mutant alleles was recommended to be investigated by identity of haplotypes. Significant characteristics of well described alleles in the reports were mentioned in this review for the benefit of future studies.

Conclusion

According to the updates in the review, it can be concluded artemisinin resistance does not disseminate to India and African countries within short period whereas regular tracking of these mutants is necessary.  相似文献   
94.
95.

Introduction

Studies on bariatric patients with cirrhosis and portal hypertension are limited. The aim of this study was to review our experience in cirrhotic patients with portal hypertension who had bariatric surgery.

Method

All cirrhotic patients with portal hypertension who underwent laparoscopic bariatric surgery, from 2007 to 2017, were retrospectively reviewed.

Results

Thirteen patients were included; eight (62%) were female. The median age was 54 years (interquartile range, IQR 49–60) and median BMI was 48 kg/m2 (IQR 43–55). Portal hypertension was diagnosed based on endoscopy (n?=?5), imaging studies (n?=?3), intraoperative increased collateral circulation (n?=?2), and endoscopy and imaging studies (n?=?3). The bariatric procedures included sleeve gastrectomy (n?=?10, 77%) and Roux-en-Y gastric bypass (n?=?3, 23%). The median length of hospital stay was 3 days (IQR 2–4). Three 30-day complications occurred including wound infection (n?=?1), intra-abdominal hematoma (n?=?1), and subcutaneous hematoma (n?=?1). No intraoperative or 30-day mortalities. There were 11 patients (85%) at 1-year follow-up and 9 patients (69%) at 2-year follow-up. At 2 years, the median percentage of excess weight loss (EWL) and total weight loss (TWL) were 49 and 25%, respectively. There was significant improvement in diabetes (100%), dyslipidemia (100%), and hypertension (50%) at 2 years after surgery.

Conclusion

Bariatric surgery in selected cirrhotic patients with portal hypertension is relatively safe and effective.
  相似文献   
96.
97.
Honey is reported to contain various compounds such as phenols, vitamins and antioxidants. The present study investigates the anticancer potential of Tualang honey (Agromas) (TH) in human breast (MCF-7 and MDA-MB-231) and cervical (HeLa) cancer cell lines; as well as in the normal breast epithelial cell line, MCF-10A. The cells were treated with increasing doses of TH (1-10%) for up to 72 h. Increase in lactate dehydrogenase (LDH) leakage from the cell membranes indicates that TH is cytotoxic to all three cancer cells with effective concentrations (EC50) of 2.4-2.8%. TH is however, not cytotoxic to the MCF-10A cells. Reactivity with annexin V fluorescence antibody and propidium iodide as analysed by flow cytometry and fluorescence microscopy shows that apoptosis occurred in these cancer cells. TH also reduced the mitochondrial membrane potential (Δψm) in the cancer cell lines after 24 h of treatment. The activation of caspase-3/7 and -9 was observed in all TH-treated cancer cells indicating the involvement of mitochondrial apoptotic pathway. This study shows that TH has significant anticancer activity against human breast and cervical cancer cell lines.  相似文献   
98.
Inophyllin A (INO-A), a pyranoxanthone isolated from the roots of Calophyllum inophyllum represents a new xanthone with potential chemotherapeutic activity. In this study, the molecular mechanism of INO-A-induced cell death was investigated in Jurkat T lymphoblastic leukemia cells. Assessment of phosphatidylserine exposure confirmed apoptosis as the primary mode of cell death in INO-A-treated Jurkat cells. INO-A treatment for only 30 min resulted in a significant increase of tail moment which suggests that DNA damage is an early apoptotic signal. Further flow cytometric assessment of the superoxide anion level confirmed that INO-A induced DNA damage was mediated with a concomitant generation of reactive oxygen species (ROS). Investigation on the thiols revealed an early decrease of free thiols in 30 min after 50 μM INO-A treatment. Using tetramethylrhodamine ethyl ester, a potentiometric dye, the loss of mitochondrial membrane potential (MPP) was observed in INO-A-treated cells as early as 30 min. The INO-A-induced apoptosis progressed with the simultaneous activation of caspases-2 and -9 which then led to the processing of caspase-3. Taken together, these data demonstrate that INO-A induced early oxidative stress, DNA damage and loss of MMP which subsequently led to the activation of an intrinsic pathway of apoptosis in Jurkat cells.  相似文献   
99.
Ginger (Zingiber officinale Rosco) is widely used in foods as a spice all around the world. It has been reported to have antioxidant and anticarcinogenic properties. We investigated the effect of ginger in ethionine induced rat hepatocarcinogenesis. Male Wistar rats were divided into 5 groups: group 1 and 2 served as controls and they received normal rat chow and olive oil respectively. Group 3 was fed with ginger oleoresin dissolved in olive oil at 100 mg/kg body wt. Group 4 was fed with choline deficient diet and 0.1% ethionine in drinking water (CDE diet), and group 5 received ginger with CDE diet. Blood samples were taken from the orbital sinus at 0 and 8 weeks of experiment for the determination of antioxidant enzymes, superoxide dismutase (SOD), glutathione peroxidase (GPx), catalase and lipid peroxidation end product, malondialdehyde (MDA). Rats were also killed at 8 weeks for the observation of liver tumor formation. CDE diet induced the formation of liver nodules in rats and increased SOD activity. However, it had no effect on catalase, GPx and MDA levels when compared to both controls at 8 weeks of experiment. When CDE rats were treated with ginger, the formation of liver tumour, SOD activity and MDA level reduced, catalase activity was increased but no change was observed for GPx activity when compared to CDE group. In conclusion, ginger supplementation suppressed liver carcinogenesis by scavenging the free radical formation, and by reducing lipid peroxidation.  相似文献   
100.
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