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   2085篇
  免费   197篇
  国内免费   4篇
耳鼻咽喉   18篇
儿科学   47篇
妇产科学   58篇
基础医学   349篇
口腔科学   51篇
临床医学   262篇
内科学   532篇
皮肤病学   47篇
神经病学   180篇
特种医学   48篇
外科学   260篇
综合类   19篇
预防医学   153篇
眼科学   38篇
药学   110篇
中国医学   6篇
肿瘤学   108篇
  2023年   23篇
  2022年   20篇
  2021年   67篇
  2020年   44篇
  2019年   65篇
  2018年   57篇
  2017年   53篇
  2016年   46篇
  2015年   44篇
  2014年   71篇
  2013年   90篇
  2012年   133篇
  2011年   128篇
  2010年   75篇
  2009年   71篇
  2008年   117篇
  2007年   128篇
  2006年   111篇
  2005年   93篇
  2004年   95篇
  2003年   77篇
  2002年   77篇
  2001年   53篇
  2000年   55篇
  1999年   36篇
  1998年   14篇
  1997年   23篇
  1996年   15篇
  1995年   12篇
  1994年   11篇
  1992年   25篇
  1991年   32篇
  1990年   24篇
  1989年   16篇
  1988年   25篇
  1987年   17篇
  1986年   28篇
  1985年   20篇
  1984年   8篇
  1983年   8篇
  1981年   11篇
  1980年   14篇
  1979年   14篇
  1978年   10篇
  1977年   14篇
  1976年   9篇
  1975年   16篇
  1974年   10篇
  1973年   13篇
  1972年   11篇
排序方式: 共有2286条查询结果,搜索用时 0 毫秒
51.
52.
BACKGROUNDMalnutrition in cirrhotic patients is correlated with mortality and a better response to liver transplantation. However, recovery of the nutritional status in these patients is a challenge due to the difficulty in establishing a reliable nutritional diagnosis. The bioelectrical impedance vector analysis (BIVA) method appears as a feasible tool in clinical practice to define the physiological state of cirrhotic patients by assessing hydration and body cellularity.AIMTo evaluate body composition in cirrhotic patients using BIVA.METHODSThis retrospective cross-sectional study was carried out by following cirrhotic outpatients at a hospital in Porto Alegre, Brazil. A tetrapolar bioelectrical impedance analysis device was used to evaluate cellularity and hydration and to perform the BIVA. The BIVA graphic was elaborated by software and for statistical analysis a significance level of 5% (P ≤ 0.05) was considered.RESULTSOne hundred and ninety patients, 61.1% males, with a mean age of 56.6 ± 11.0 years, were evaluated. Of these, 56.3% had Child-Turcotte-Pugh (CTP) A score, and the prevalent etiology was hepatitis C virus (47.4%). The patients were classified according to cellularity and hydration by the quadrants and ellipses of the BIVA method, quadrant 1 (47.9%); quadrant 2 (18.9%); quadrant 3 (14.2%); and quadrant 4 (18.9%). Those classified in quadrant 1 and 2 had a higher phase angle compared to those in quadrants 3 and 4 (P < 0.001). Quadrant 2 patients had a lower average age than the other groups. The association with CTP score showed that patients in quadrant 2 had a higher proportion of CTP A, and those in quadrant 4 had a higher proportion of CTP C (P < 0.052).CONCLUSIONThe BIVA method allows identification of the cellularity and hydration status of cirrhotic patients, and its association with clinical factors determines the disease severity, age and prognostic index.  相似文献   
53.
Electrospun nanofibers are used for many applications due to their large surface area, mechanical properties, and bioactivity. Bacterial biofilms are the cause of numerous problems in biomedical devices and in the food industry. On the other hand, these bacterial biofilms can produce interesting metabolites. Hence, the objective of this study is to evaluate the efficiency of poly (Ɛ- caprolactone)/Curcumin (PCL/CUR) nanofibers to promote bacterial biofilm formation. These scaffolds were characterized by scanning electron microscopy (SEM), which showed homogeneous fibers with diameters between 441–557 nm; thermogravimetric analysis and differential scanning calorimetry (TGA and DSC) demonstrated high temperature resilience with degradation temperatures over >350 °C; FTIR and 1H-NMR serve as evidence of CUR incorporation in the PCL fibers. PCL/CUR scaffolds successfully promoted the formation of Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa biofilms. These results will be valuable in the study of controlled harvesting of pathogenic biofilms as well as in metabolites production for biotechnological purposes.  相似文献   
54.
Visceral leishmaniasis (VL) is a neglected disease and is fatal if untreated. Dogs serve as reservoirs for Leishmania infantum (syn. L. chagasi) due to their susceptibility to infection and high skin parasitism. Therefore, VL control in Brazil involves the elimination of seropositive dogs, among other actions. However, the most frequently used serological tests have limitations regarding sensitivity and specificity. In this study, we have selected three Leishmania antigens (C1, C8 and C9) and have produced them as recombinant proteins using pET-28a-TEV vector and Escherichia coli BL-21 as expression system. When tested in ELISA with human samples, the C9 antigen was the one showing the most promising results, with 68% sensitivity and 78% specificity. When testing canine samples, the C1, C8 and C9 antigens showed a sensitivity range from 70% to 80% and specificity range from 60% to 90%. The C1 antigen presented higher sensitivity (80%) and the C8 antigen presented higher specificity (90%). Due to it, we decided to mix and test C1 and C8 antigens together, resulting in the C18 antigen. The mix also yielded high percentages of detected symptomatic and asymptomatic dogs however it did not improve the performance of the diagnostic. Comparison of our tests with the tests recommended by the Brazilian Ministry of Health revealed that our antigens’ sensitivities and the percentage of detected asymptomatic dogs were much higher. Our results suggest that the C1, C8, C18 and C9 recombinant proteins are good antigens to diagnose canine visceral leishmaniasis and could potentially be used in screening tests. To diagnose human visceral leishmaniasis, the C9 antigen presented reasonable results, but more optimization must be performed for this antigen to provide better performance.  相似文献   
55.
56.
57.
Background: This study reports and analyzes a large series of patients with neurosensory deficiency related to the placement of dental implants (DIs) and resulting in liability claims (LCs). Methods: From 1998 to 2009, there were 92 LCs related to persistent altered sensation post DI placements in Israel. Patients’ demographics, year and source of LCs, interval between the procedure that resulted in a neurosensory deficiency and the LC, qualifications of the surgeon, preoperative imaging modality, DI length, available alveolar bone for DI placement, placement site, timing of DI placement (immediately after tooth extraction or after socket healing), and treatment after the diagnosis of neurosensory deficiency were recorded and analyzed. Results: There were 21 cases during the first 5 years of the study (mean 4.2/year) and 63 cases (mean 12.6/year) over the following 5 years. Thirty LCs were issued during the second postoperative year and 15 LCs after >5 years. Most LCs (76%) involved procedures that were planned and performed according to radiographs and 24% after computed tomography. Sixty‐five percent of the LCs were performed by general dental practitioners and 35% by specialists. More than one DI was performed during the surgical procedure that resulted in a neurosensory deficiency in 73 LCs (79.3%), and the DI was >10 mm in 55 (59.8%) cases. Conclusions: LCs for DIs that result in a neurosensory deficiency pose a legal risk to the practitioner long after the injury has occurred.  相似文献   
58.
We report resolution of an epileptic encephalopathy by administration of transdermal nicotine patches in an adolescent with severe nonlesional refractory frontal lobe epilepsy. The 18.5‐year‐old female patient had refractory epilepsy from the age of 11. Recurrent electroencephalography (EEG) recordings showed mostly generalized activity, albeit with right frontal predominance. Almost all antiepileptic medications failed to provide benefit. She developed an encephalopathic state with cognitive decline. The nonlesional frontal lobe epilepsy and a family history of a cousin with nocturnal epilepsy with frontal origin suggested genetic etiology. Transdermal nicotine patches brought complete resolution of the seizures, normalization of the EEG, and a significant improvement in her thinking process and speech organization. Sequencing of the CHRNB2 and CHRNA4 genes did not detect a mutation. Transdermal nicotine patches should be considered in severe pharmacoresistant frontal lobe epilepsy.  相似文献   
59.

Background

Perioperative short-term outcomes could be improved after totally robotic Roux-en-Y gastric bypass (TR-RYGBP) compared with conventional laparoscopic gastric bypass.

Methods

This is a nonrandomized controlled prospective study (N = 200) to evaluate perioperative short-term outcomes. The primary endpoint was to investigate risk factors for 30-day surgical complications.

Results

Mean total operative time was shorter in patients who underwent TR-RYGBP (130 vs 147 minutes; P < .0001). However, postoperative surgical complications rate (13% vs 1%; P = .001), and mean overall hospital stay (9.3 vs 6.7 days; P < .0001) were higher after TR-RYGBP. By multivariate analysis, robotic surgery (hazard ratio [HR] = 15.1; 95% confidence interval [CI], 2.8 to 280; P = .01), and conversion to laparotomy (HR = 18.8; 95% CI, 1.7 to 250.8; P = .014) were independent risk factors for 30-day surgical complications.

Conclusions

Although robotic gastric bypass reduces mean operative time, TR-RYGBP is associated with an increased postoperative surgical complications rate and longer hospitalization.  相似文献   
60.
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