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   775篇
  免费   46篇
  国内免费   5篇
耳鼻咽喉   6篇
儿科学   38篇
妇产科学   29篇
基础医学   60篇
口腔科学   80篇
临床医学   103篇
内科学   153篇
皮肤病学   3篇
神经病学   42篇
特种医学   16篇
外科学   62篇
综合类   3篇
预防医学   59篇
眼科学   7篇
药学   101篇
中国医学   22篇
肿瘤学   42篇
  2023年   24篇
  2022年   37篇
  2021年   44篇
  2020年   36篇
  2019年   20篇
  2018年   29篇
  2017年   33篇
  2016年   34篇
  2015年   30篇
  2014年   44篇
  2013年   66篇
  2012年   46篇
  2011年   57篇
  2010年   40篇
  2009年   25篇
  2008年   47篇
  2007年   32篇
  2006年   31篇
  2005年   25篇
  2004年   15篇
  2003年   16篇
  2002年   11篇
  2001年   10篇
  2000年   9篇
  1999年   12篇
  1998年   13篇
  1997年   8篇
  1996年   3篇
  1995年   1篇
  1994年   5篇
  1993年   2篇
  1992年   3篇
  1991年   6篇
  1990年   3篇
  1989年   3篇
  1988年   1篇
  1987年   1篇
  1986年   4篇
排序方式: 共有826条查询结果,搜索用时 31 毫秒
771.
AIM:To determine the clinical presentations, survival and prognostic factors of hepatocellular carcinoma (HCC) in Southern Thailand.METHODS:Retrospective analysis was performed on the 336 hepatocellular carcinoma patients treated at Songklanagarind hospital between 1 January 1991 and 31 January 1999.RESULTS:Of these 336 patients, 276 were males and 60 were females. The mean age was 54.4 years. The common symptoms and signs were abdominal pain and hepatomegaly. The most common presentation of tumor was a dominant mass with daughter nodules. Portal vein involvement was found in 50% of total. Extrahepatic metastasis was found in 13%, and the lung was the most common site. There were 65.4% with evidence of cirrhosis and half of them were in Child's class B. HBsAg was positive in 72.6%. Regarding a(c)Okuda's tumor staging, 15%, 61% and 24% were stage I, II and III, respectively. Overall median survival was 2.1 months (11.5 2.6 and 0.7 months for stage I, II and III respectively). Treatments of HCC improved patient survival (5.5 months vs 1.6 months for untreated patients). Most common causes of death were hepatic failure. Using multivariate analysis, the prognostic factors identified were tumor staging, alpha-fetoprotein level above 10000&mgr;gcenter dotL(-1), extrahepatic metastasis, portal vein thrombosis and treatment.CONCLUSION:HCC in Thailand is a fatal disease with poor outcome due to late presentation and high prevalence of liver cirrhosis. Early detection and proper management may improve outcome.  相似文献   
772.
Background/objectiveRe-staging of locally advanced rectal cancer (LARC) following neoadjuvant chemoradiotherapy (NCRT) is a crucial step in surgical decision-making. Currently, MRI is the imaging of choice for evaluation of LARCs, however, the diagnostic accuracy of this modality is inconsistent. In this study, we evaluated the diagnostic accuracy of MRI in LARC and analyzed the factors that influenced the accuracy.MethodsThe records of 133 patients diagnosed with LARC who were operated on during 2011–2018 were retrospectively reviewed. All patients received NCRT followed by re-staging based on high-resolution rectal MRI. The MRI results were analyzed for their yT and yN accuracy and anal sphincter involvement and compared with the related histopathological studies after definitive surgery.ResultsRe-staging MRIs gave overall accuracy in both the yT stage and yN evaluation of 85% (K 0.45 and 0.21, respectively). The MRI tended to overstaging for tumor invasion and understaging for lymph node involvement (sign test p-values = 0.017 and 0.022, respectively.) The highest accuracy of the yT stage was yT4b (93%, K 0.71). The study found that larger tumors (>3 cm) were associated with significantly higher accuracy in the yT readings while lack of lymphovascular invasion was associated with higher accuracy in the yN readings. The negative predictive value for anal sphincter involvement was 100%.ConclusionMRI has limited accuracy in post-NCRT re-staging in LARC, tending to give overstaged yT readings and understaged yN readings. An MRI exclusion of sphincteric involvement is highly reliable.  相似文献   
773.

Objectives

To investigate the effectiveness of family intervention for type 2 diabetes and to examine predictors of glycaemic control.

Methods

This was a prospective randomised controlled trial. Participants with type 2 diabetes were randomly assigned to an intervention group (n?=?98) or a control group (n?=?98). A pharmacist delivered the educational sessions and encouraged family members to take an active role in self-management practices for the intervention patients. The control patients received usual care.

Results

At the end of the study (9-month follow-up), greater reduction in glycosylated haemoglobin (HbA1c) occurred in the intervention group than in the control group (?1.37% and ?0.21%, respectively; P?<?0.001). Between-group differences in the improvements of low-density lipoprotein cholesterol (LDL-C) and blood pressure were found (P?<?0.05). Higher scores in diabetes knowledge of patients, family support, medication adherence, self-management and self-efficacy were seen in the intervention group than in the control group (P?<?0.05). Multivariable analysis showed family members who were spouses or women were strong predictors of improved glycaemic control.

Conclusion

Family-involvement intervention is helpful in diabetes management, especially having spouses or women as caregivers.

Practice implications

Family involvement should be encouraged in diabetes care.  相似文献   
774.
ABSTRACT

In previous studies, we have demonstrated that very virulent plus Marek’s disease viruses (vv+MDV) are highly immunosuppressive in commercial meat-type chickens. The specific objectives of this work were to evaluate if vv+MDV immunosuppression (MDV-IS) is induced by reduction of lymphocyte responsiveness and/or viability. Three experiments were conducted to (i) compare vv+MDV 686 with a partially attenuated 686-BAC; (ii) compare vv+MDV strains (648A and 686) with vMDV (GA) and vvMDV (Md5); and (iii) compare chickens vaccinated with Md5-BACΔMEQ and with CVI988?+?HVT. In each experiment, spleens were collected at 28–30 days post infection and lymphocytes were isolated and investigated in three ways: their proliferative response to Concanavalin A (ConA) was analysed by MTT proliferation assay; cell death, and expression of CD45 and MHC-I was studied by flow cytometry; and MHC-IA and β-2 microglobulin (B2M) expression was evaluated by real time RT-PCR. Splenocytes of chickens inoculated with vv+MDV were severely impaired to proliferate when exposed to ConA. Furthermore, vv+MDV induced severe splenocyte death that did not occur after infection with v or vvMDV strains. Vaccination with CVI988?+?HVT, and at less level with Md5-BACΔMEQ reduced these negative effects. This is in contrast to our previous results in which Md5-BACΔMEQ but not CVI988?+?HVT protected against MDV-IS suggesting that although cell death and decrease lymphocyte function seem to be related to MDV virulence and certainly will be associated with immunosuppression, they might not fully explain the previously reported MDV-IS.

RESEARCH HIGHLIGHTS
  • vv+MDV induces extensive death in splenocytes in meat-type chickens 28–30?dpi.

  • vv+MDV impairs lymphocyte function in meat-type chickens 28–30?dpi.

  • Vaccination protects against splenocyte death and reduced lymphocyte function.

  • Cell lysis and reduced lymphocyte function do not fully explain MDV-IS.

  相似文献   
775.
Cyanoacrylate (CA) has been used as both a commercial and tissue adhesive. Dentists may have had the experience of patients repairing their own acrylic-based dentures using a cyanoacrylate (CA) adhesive known as 'super glue'. This study evaluated the cytotoxicity of commercial CA adhesives when fully polymerized, as well as the toxicity of substances released from polymerized commercial CA adhesives after incubation of these materials for various periods of time. Toxicity was tested on cultured oral fibroblasts. Dead cells found around the various CA-coated filter papers constituted inhibitory zones which varied from 200-1000 microns and which persisted for two weeks. Control oral fibroblasts grew to approach the wax-coated filter paper. Cell viability testing using MTT and crystal violet staining methods supported the conclusion that polymerized CA-coated filter paper released substances that are toxic to cells, while wax-coated filter paper gave the same result as the control. The crystal violet staining method was also used to investigate the cytotoxicity of various CA materials after incubation for one, three, seven and 14 days and showed that CA continued to release cytotoxic substances at about the same level for at least two weeks. It can be concluded that, if CA adhesive is used for repair of broken dentures, it will release substances which are toxic to human oral fibroblast cells. This release of substances may persist for at least two weeks.  相似文献   
776.
《Explore (New York, N.Y.)》2023,19(3):445-449
ObjectiveTo investigate the effect of Qili Qiangxin Capsule combined with cardiac exercise rehabilitation on patients with chronic heart failure (CHF).MethodsA total of 93 CHF patients admitted to Shanghai's Putuo District Central Hospital from March 2021 to December 2021 were included in the study and were randomly divided into the control group (46 cases) and the intervention group (47 cases). The control group received routine treatment, and the intervention group was treated with Qili Qiangxin Capsule as well as cardiac exercise rehabilitation that was routine for patients with CHF. The total effective rate, 6-min walking distance, left ventricular ejection fraction, B-type natriuretic peptide (BNP) level, left ventricular end-systolic diameter, and left ventricular end-diastolic diameter were compared in terms of the two groups.ResultsAfter three months of treatment, when compared with the control group, the total effective rate of the treatment on the patients in the intervention group increased significantly (87.23% vs 63.04%; P < 0.05). The 6-minute walking distance, BNP level, and the left ventricular end-diastolic diameter improved more drastically in the intervention group than in the control group, and the differences were statistically significant (P < 0.05). There was no significant difference in the other indicators before and after treatment (P > 0.05).ConclusionQili Qiangxin Capsule combined with cardiac exercise rehabilitation can significantly improve cardiac and motor function in patients with CHF.  相似文献   
777.
Large amounts of new data on the natural history and treatment of chronic hepatitis B virus (HBV) infection have become available since 2005. These include long-term follow-up studies in large community-based cohorts or asymptomatic subjects with chronic HBV infection, further studies on the role of HBV genotype/naturally occurring HBV mutations, treatment of drug resistance and new therapies. In addition, Pegylated interferon α2a, entecavir and telbivudine have been approved globally. To update HBV management guidelines, relevant new data were reviewed and assessed by experts from the region, and the significance of the reported findings were discussed and debated. The earlier “Asian-Pacific consensus statement on the management of chronic hepatitis B” was revised accordingly. The key terms used in the statement were also defined. The new guidelines include general management, special indications for liver biopsy in patients with persistently normal alanine aminotransferase, time to start or stop drug therapy, choice of drug to initiate therapy, when and how to monitor the patients during and after stopping drug therapy. Recommendations on the therapy of patients in special circumstances, including women in childbearing age, patients with antiviral drug resistance, concurrent viral infection, hepatic decompensation, patients receiving immune-suppressive medications or chemotherapy and patients in the setting of liver transplantation, are also included. Other members of the working party: Rong-Nan Chien, Anuchit Chutaputti, Graham Cooksley, S. M. Wasim Jafri, Laurentius A. Lesmana, Seng-Gee Lim, Rosmawati Mohamed, Masao Omata, Pham Hoang Phiet, Shiv Kumar Sarin, Jose Sollano, Dong-Jin Suh, Guang-Bi Yao, Osamu Yokosuka. An erratum to this article can be found at  相似文献   
778.
This study aimed to evaluate the cytotoxicity of a crude extract of Piper cubeba against normal and breast cancer cell lines. To prepare the extract, P. cubeba seeds were ground, soaked in methanol and dichloromethane and isolated by column chromatography. Fractions were tested for cytotoxicity effects on normal fibroblast (L929), normal breast (MCF-12A) and breast cancer cell lines (MCF-7, MDA-MB-468 and MDA-MB-231). The most effective fraction was selected for DNA fragmentation assay to detect apoptotic activity. The results showed that the methanolic crude extract had a higher cytotoxic activity against MDA-MB-468 and MCF-7 than a dichloromethane crude extract. Then, the methanolic crude extract was separated into six fractions, designated A to F. Fraction C was highly active against breast cancer cell lines with an IC50 value less than 4 μg/mL. Therefore, Fraction C was further separated into seven fractions, CA to CG. The 1H-NMR profile showed that Fraction CE was long chain hydrocarbons. Moreover, Fraction CE demonstrated the highest activity against MCF-7 cells with an IC50 value of 2.69 ± 0.09 μg/mL and lower cytotoxicity against normal fibroblast L929 cells with an IC50 value of 4.17 ± 0.77 μg/mL. Finally, DNA fragmentation with a ladder pattern characteristic of apoptosis was observed in MCF-7, MDA-MB-468, MDA-MB-231 and L929 cells, but not in MCF-12A cells.  相似文献   
779.
Hepatitis E virus (HEV) is the most common cause of acute hepatitis worldwide including large water-borne outbreaks, zoonotic infections and transfusion transmissions. Several countries have initiated or are considering blood donor screening in response to high HEV-RNA donation prevalence leading to transfusion-transmission risk. Because HEV transmission is more common through food sources, the efficacy of blood donor screening alone may be limited. HEV-nucleic acids in 101 489 blood donations in the United States and Canada were studied. A risk-based decision-making framework was used to evaluate the quantitative risks and cost–benefit of HEV-blood donation screening in Canada comparing three scenarios: no screening, screening blood for all transfused patients or screening blood for only those at greatest risk. HEV-RNA prevalence in the United States was one per 16 908 (95% confidence interval [CI], 1:5786–1:81987), whereas Canadian HEV-RNA prevalence was one per 4615 (95% CI, 1:2579–1:9244). Although 4-fold greater, Canadian HEV-RNA prevalence was not significantly higher than in the United States. Viral loads ranged from 20 to 3080 international units per mL; all successfully typed infections were genotype 3. No HEV-RNA false-positive donations were identified for 100 percent specificity. Without donation screening, heart and lung transplant recipients had the greatest HEV-infection risk (1:366962) versus kidney transplant recipients with the lowest (1:2.8 million) at costs of $225 546 to $561 810 per quality-adjusted life-year (QALY) gained for partial or universal screening, respectively. Higher cost per QALY would be expected in the United States. Thus, HEV prevalence in North America is lower than in countries performing blood donation screening, and if implemented, is projected to be costly under any scenario.  相似文献   
780.
Thai medicinal plants represent a rich source of potential anti-parasitic compounds. 1-hydroxy-2-hydroxymethylanthraquinone (CFQ) purified from Coptosapelta flavescens, a plant commonly used to expel intestinal worms, indicated potential anti-giardial agent as shown in a previous study. This study aims to investigate its mechanism of action. We assessed whether CFQ was involved as an inducer of apoptosis as well as having effects on the fine structure of Giardia intestinalis trophozoites. We observed the consequences of exposing G. intestinalis trophozoites to CFQ and metronidazole, both had an IC50 of 0.42 μg/ml, after 6, 12 and 24 h exposure. An apoptosis in trophozoite was confirmed by the AnnexinV-FITC assay and as viewed by flow cytometry. CFQ at its IC50 induced apoptosis as early as 6 h after incubation while metronidazole produced little or no apoptosis at its IC50 value. Ultrastructural analyzes at 24 h demonstrated that both CFQ and metronidazole induced several physical alterations, including the appearance of wrinkled and rounded cells, membrane blebbing, ventral disc damage, electron dense precipitates in the nuclei, all of which were indicative of cell death. However, membrane rupture was found only in G. intestinalis exposed to CFQ and this proved the induction of apoptosis. Taken together, we have provided a mechanistic explanation of the action of CFQ against G. intestinalis trophozoites. These results have provided further evidence that CFQ is a new compound that has the potential for use to treat infections from G. intestinalis.  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