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   1746篇
  免费   95篇
  国内免费   13篇
耳鼻咽喉   11篇
儿科学   57篇
妇产科学   42篇
基础医学   159篇
口腔科学   47篇
临床医学   169篇
内科学   292篇
皮肤病学   53篇
神经病学   116篇
特种医学   53篇
外科学   254篇
综合类   46篇
一般理论   1篇
预防医学   106篇
眼科学   79篇
药学   209篇
中国医学   25篇
肿瘤学   135篇
  2024年   4篇
  2023年   31篇
  2022年   64篇
  2021年   109篇
  2020年   71篇
  2019年   139篇
  2018年   97篇
  2017年   64篇
  2016年   83篇
  2015年   73篇
  2014年   83篇
  2013年   107篇
  2012年   138篇
  2011年   138篇
  2010年   68篇
  2009年   65篇
  2008年   77篇
  2007年   77篇
  2006年   72篇
  2005年   39篇
  2004年   37篇
  2003年   24篇
  2002年   25篇
  2001年   14篇
  2000年   7篇
  1999年   12篇
  1998年   4篇
  1997年   4篇
  1996年   3篇
  1995年   4篇
  1994年   3篇
  1993年   3篇
  1992年   19篇
  1991年   13篇
  1990年   9篇
  1989年   11篇
  1988年   12篇
  1987年   5篇
  1986年   3篇
  1985年   3篇
  1984年   3篇
  1983年   9篇
  1982年   4篇
  1981年   2篇
  1979年   5篇
  1975年   4篇
  1974年   4篇
  1971年   4篇
  1967年   1篇
  1965年   2篇
排序方式: 共有1854条查询结果,搜索用时 15 毫秒
61.

Background

Large bony defects in the middle or distal third of the tibia resulting from surgical resection of malignant bone tumors present a difficult reconstructive challenge. Various methods of reconstruction are available, such as allografts, vascularized fibular graft (either free or pedicled), or endoprothesis replacement for distal defects.

Materials and methods

Twelve patients—eight males and four females with mean age of 18 years at operation (range 14–25 years)—with malignant bone tumors of the tibial shaft were selected as candidates for wide resection of the tumor and reconstruction of the bony defect by ipsilateral vascularized fibular graft based on the peroneal vessels. Preoperative staging studies, including plain radiography, local MRI, isotopic bone scan, and chest CT, were done for every patient before biopsy. Ilizarov external fixation was then applied in all cases. The average length of the bony gap bridged was 14.5 cm (13–16.5 cm) and the mean length of the harvested graft was 16.3 cm (15–18 cm). The average operation time was 7.5 h (5.5–9.5 h).

Results

The mean follow-up period was 38 months (range 32–52 months). Bony union at the proximal and distal ends of the fibula occurred in nine patients (75 %) and at a mean time of 5.5 months (range 4.5–8 months). Graft hypertrophy occurred in all patients. The mean percentage of hypertrophy was 95 % (range 80–160 %). The mean MSTS functional score was 84 % (range 80–92 %). A leg length discrepancy of 2 cm was reported in two patients and was managed using a shoe lift.

Conclusion

Reconstruction of bony defects of the middle or distal tibia after bone tumor resection using pedicled vascularized fibula is a useful limb salvage procedure. The procedure can be performed relatively quickly and inexpensively and has a low rate of late complications. It leads to a good outcome regarding the union, hypertrophy, and function.  相似文献   
62.
Optimal nutrition is critical to the attainment of healthy growth, human capital and sustainable development. In Egypt, infants and young children face overlapping forms of malnutrition, including micronutrient deficiencies, stunting and overweight. Yet, in this setting, little is known about the factors associated with growth during the first year of life. A rise in stunting in Lower Egypt from 2005 to 2008 prompted this implementation research study, which followed a longitudinal cohort of infants from birth to 1 year of age within the context of a USAID‐funded maternal and child health integrated programme. We sought to determine if growth patterns and factors related to early growth differed in Lower and Upper Egypt, and examined the relationship between weight loss and subsequent stunting at 12 months of age. Growth patterns revealed that length‐for‐age z‐score (LAZ) decreased and weight‐for‐length z‐score (WLZ) increased from 6 to 12 months of age in both regions. One‐quarter of infants were stunted and nearly one‐third were overweight by 12 months of age in lower Egypt. Minimum dietary diversity was significantly associated with WLZ in Lower Egypt (β = 0.22, P < 0.05), but not in Upper Egypt. Diarrhoea, fever and programme exposure were not associated with any growth outcome. Weight loss during any period was associated with a twofold likelihood of stunting at 12 months in Lower Egypt, but not Upper Egypt. In countries, like Egypt, facing the nutrition transition, infant and young child nutrition programmes need to address both stunting and overweight through improving dietary quality and reducing reliance on energy‐dense foods.  相似文献   
63.
In the neck or face, there are different causes for subcutaneous emphysema such as injury to the sinuses, the hypopharynx, the laryngotracheal complex, the pulmonary parenchyma, the esophagus or the presence of gas-forming organisms. However, factitious subcutaneous emphysema, a rare cause, must be considered in the differential diagnosis. In this clinical report, we discuss a 20-year-old girl who was under follow-up because of recurrent subcutaneous emphysema of the face and periorbital area.After 2 years of work-ups, including a period of close observation in the intensive care unit, self air injection by syringe was found as the cause of recurrent subcutaneous emphysema of the face, and the patient was labeled as having factitious recurrent subcutaneous emphysema. Therefore, when a patient presents with unexplained recurrent subcutaneous emphysema, one should suspect self-infliction and examine for puncture marks.  相似文献   
64.
65.
Graefe's Archive for Clinical and Experimental Ophthalmology - To evaluate the effect of systemic erythropoietin, as well as oral steroids, in the management of recent-onset non-arteritic...  相似文献   
66.
Purpose: To evaluate the responsiveness of two outcome measures of participation restriction [as measured by the Community Integration Questionnaire (CIQ)] and quality of life [as measured by the Multiple Sclerosis Quality of Life (MSQOL)] following a physiotherapy intervention in patients with multiple sclerosis (MS). Method: A sample of 265 patients completed both instruments first at the time of initial visit and then after 4–6 weeks physiotherapy. In addition, patients were asked to complete the 7-point global rating scale as an external criterion of change at the post-intervention time. The responsiveness was evaluated using the receiver operating characteristics (ROC) method and the correlation analysis. Two useful statistics were area under the ROC curve (AUC) and the minimally clinically important difference (MCID). The AUC and correlation coefficient greater than 0.70 were considered as acceptable responsiveness. Results: The CIQ achieved the acceptable responsiveness with an AUC of 0.81. However, the AUCs of 0.61 and 0.66 were obtained for the MSQOL physical and mental, respectively. Moreover, good correlation coefficient was obtained for the CIQ (Gamma?=?0.76) while fair correlations of 0.28 and 0.33 were obtained for the MSQOL physical and mental, respectively. The MCIDs were approximately 0.50, 1.5 and 2.5 points for the CIQ, MSQOL physical and mental, respectively. Conclusions: In contrast to the MSQOL, the CIQ was responsive outcome measure in detecting changes in participation restriction of patients with MS. Moreover, the MCID values obtained in this study will help the clinicians and researchers to determine if a patient with MS has experienced a true change following physiotherapy intervention.
  • Implications for Rehabilitation
  • The results provide valuable information regarding to the ability of two outcome measures (i.e. the CIQ and MSQOL) to detect treatment effects in patients with MS.

  • In contrast to the MSQOL, the CIQ is a responsive measure to changes in participation restriction due to physiotherapy.

  • A patient with MS had to change at least 0.50 point on the CIQ, 1.5 points on the MSQOL physical and 2.5 points on the MSQOL mental to be judged as having clinically changed.

  相似文献   
67.
The current study aimed to investigate the protective potential of Chlorella Vulgaris (CV) extract against the reproductive dysfunction induced by sodium nitrite toxicity. Forty-five male Wistar albino rats were assigned into five groups (n = 9). Control group received normal saline orally for 3 months, CV-treated: administered CV extract (70 mg/kg.BW) orally for 3 months, sodium nitrite-treated: received sodium nitrite (80 mg/kg.BW) orally for 3 months, co-treated: simultaneously received CV along with sodium nitrite treatment, orally, daily for 3 months, and CV-pre-treated: pre-treated with CV extract for 4 weeks followed by simultaneous treatment with sodium nitrite and CV extract for additional 8 weeks. Treatment with sodium nitrite significantly decreased serum testosterone and follicle-stimulating hormone concentrations, sperm count, motility, and viability. Besides, it decreased testicular superoxide dismutase and glutathione peroxidase activities while increased malondialdehyde concentration. This effect of sodium nitrite was associated with degenerative, necrotic, vascular, and inflammatory changes in testicular tissues. Treatment of sodium nitrite-intoxicated rats with CV in co-treated and pre-treated groups significantly prevented sodium nitrite-induced alterations of sperm parameters, hormonal concentrations, testicular oxidative–antioxidant status, and histological architecture. This study indicates that CV extract ameliorates the reproductive dysfunction induced by sodium nitrite toxicity via improving reproductive hormonal levels and testicular antioxidant activities.  相似文献   
68.
Among various health issues, infertility has been always considered as one of the major health problems. Idiopathic infertility is still a matter of debate since the underlying mechanisms stay obscure. Idiopathic infertility is related to expanded chance of metabolic syndrome components, obesity and increased risk of cardiovascular diseases. This study aimed to assess insulin resistance and serum levels of irisin as one of the adipokines in patients with idiopathic infertility. This study included 50 male patients aged 25–50 years old suffering from idiopathic infertility, together with 50 healthy individuals of matched age as controls. Patients showed significantly increased homeostasis model assessment for insulin resistance values than controls. For irisin results, idiopathic infertility patients had significantly decreased values than controls indicating the potential effect of irisin in development of insulin resistance in idiopathic infertility patients.  相似文献   
69.
Developing a new drug is expensive: the cost of going from bench to bedside is about $US1 billion. Therefore, the repurposing of an approved drug is potentially rewarding because it expands the drug's existing therapeutic profile and preempts additional development costs. As the safety profile of a repurposed drug is already well known, any new investigations could then focus on its efficacy and other therapeutic benefits. Recombinant erythropoietin (EPO) is a potential candidate for repurposing because the results of numerous studies have shown that systemic and topical EPO is therapeutically beneficial when it is administered to healthy and diabetic animals with acute and chronic skin wounds and burns. Moreover, the molecular mechanisms of EPO's actions have been elucidated: EPO acts on those nonhematopoietic cells which are involved in the innate immune response where it promotes cellular proliferation and differentiation, exerts its cytoprotective actions, and inhibits apoptosis. In this review, the mechanism of EPO's action in skin wound healing is reviewed, and its potential for treating acute and chronic skin wounds and stimulating tissue regeneration in diabetic patients is discussed.  相似文献   
70.

Purpose

Oxidation therapy is an antitumor strategy in which, apoptosis or necrosis is caused by either excess delivery of reactive oxygen species (ROS) as an oxidant or anti-oxidant inhibition. Heme oxygenase (HO) is an anti-oxidant enzyme that plays an important role in cell growth and proliferation. The purpose of this study was to prepare poly lactic-co-glycolic acid (PLGA) nanoparticles (NPs) loaded with zinc protoporphyrin (ZnPP) to deliver the HO inhibitor into tumor.

Methods

PLGA NPs were prepared using nanoprecipitation technique and their characteristics were optimized by Box-Behnken experimental design. Scanning electron microscopy and in vitro studies consisting of drug release, HO inhibitory effect, cytotoxicity and cellular uptake followed by in vivo biodistribution and blood cytotoxicity were carried out. Internalization of coumerin-6 loaded NPs by PC3 cells was visualized by confocal laser scanning microscopy beside quantitatively analysis.

Results

NPs average size, entrapment efficiency and drug loading were 100.12?±?5.345 nm, 55.6%?±?2.49 and 7.98%?±?0.341 respectively. Equal HO inhibitory effect of NPs compared to free ZnPP was observed. The IC50 value of ZnPP-NPs for PC3 human prostate cancer cells was found to be 2.14?±?0.083 μM.

Conclusion

In conclusion, ZnPP loaded PLGA NPs could exhibit enough HO inhibitory effect against cancer cells to be considered as a promising candidate for cancer treatment investigation.  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