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   4601篇
  免费   311篇
  国内免费   4篇
耳鼻咽喉   86篇
儿科学   125篇
妇产科学   115篇
基础医学   478篇
口腔科学   611篇
临床医学   237篇
内科学   955篇
皮肤病学   112篇
神经病学   300篇
特种医学   74篇
外科学   655篇
综合类   10篇
一般理论   2篇
预防医学   456篇
眼科学   331篇
药学   212篇
中国医学   64篇
肿瘤学   93篇
  2023年   14篇
  2022年   69篇
  2021年   106篇
  2020年   87篇
  2019年   111篇
  2018年   165篇
  2017年   140篇
  2016年   132篇
  2015年   146篇
  2014年   219篇
  2013年   241篇
  2012年   284篇
  2011年   336篇
  2010年   181篇
  2009年   179篇
  2008年   264篇
  2007年   296篇
  2006年   273篇
  2005年   252篇
  2004年   203篇
  2003年   151篇
  2002年   156篇
  2001年   123篇
  2000年   110篇
  1999年   69篇
  1998年   48篇
  1997年   29篇
  1996年   24篇
  1995年   17篇
  1994年   13篇
  1993年   17篇
  1992年   29篇
  1991年   47篇
  1990年   24篇
  1989年   17篇
  1988年   19篇
  1987年   19篇
  1986年   24篇
  1985年   24篇
  1984年   17篇
  1983年   14篇
  1979年   14篇
  1977年   11篇
  1971年   14篇
  1970年   22篇
  1969年   27篇
  1968年   15篇
  1967年   20篇
  1966年   14篇
  1965年   12篇
排序方式: 共有4916条查询结果,搜索用时 15 毫秒
91.

Background

C.E.R.A. is a continuous erythropoietin receptor activator with characteristics that permit a once-monthly schedule of administration for the maintenance treatment for chronic kidney disease (CKD) patients. The main objective of this study was to assess the maintenance of Hb concentration with once-monthly intravenous and/or subcutaneous C.E.R.A. therapy in Latin American dialysis patients with chronic renal anemia previously treated with epoetin alfa s.c or i.v 1–3 times per week.

Methods

This was a single-arm, open-label, multicenter, 32-week study of anemic patients with CKD previously treated with epoetin alfa sc or iv 1–3 times per week. After a 4-week screening period, during which mean Hb levels were maintained between 10.5 and 12.5 g/dL on their previous erythropoiesis stimulating agent, eligible patients entered a 16-week C.E.R.A. dose titration period followed by a 4-week efficacy evaluation period (EEP) and a 28-week safety follow-up. The starting dose of C.E.R.A. was based on the previous dose of epoetin alfa. Doses of C.E.R.A. were then adjusted to maintain Hb levels within ±1.0 g/dL of the reference concentration and between 10.5 and 12.5 g/dL. The Hb reference concentration was defined as the mean of all Hb levels during screening. The primary end point was the proportion of patients maintaining a mean Hb concentration (g/dL) within ±1 g/dL of their reference Hb and between 10.5 and 12.5 g/dL during the EEP.

Results

A total of 163 patients from 27 centers in Argentina, Brazil, Chile, Colombia, Ecuador, Mexico, Peru, Uruguay, and Venezuela entered the treatment period and 102 completed the prescribed course of C.E.R.A. Forty-five patients (43.7 %) maintained a mean Hb concentration within ±1 g/dL of their reference Hb value and between 10.5 and 12.5 g/dL during the EEP. The median monthly dose remained constant at 120 μg during the titration period and during the EEP. On the average, there were only 2.3 dose changes per patient in 28 weeks of treatment, covering 7 C.E.R.A. scheduled administrations. 53 % of all dose changes were dose decreases, 47 % increases. A total of 10 AEs and 4 SAEs were considered to be related to the study treatment.

Conclusions

Once-monthly C.E.R.A. treatment effectively maintains stable Hb concentrations in patients with chronic renal anemia undergoing dialysis with a good safety and tolerability profile.  相似文献   
92.
Although long known and the most prevalent movement disorder, pathophysiology of essential tremor (ET) remains controversial. The most accepted hypothesis is that it is caused by a dysfunction of the olivocerebellar system. Vilela Filho et al. [2001; Stereotact Funct Neurosurg 77:149–150], however, reported a patient with unilateral hand ET that was completely relieved after a stroke restricted to the contralateral posterior putamen and suggested that ET could be the clinical manifestation of posterior putamen hyperactivity. The present study was designed to evaluate this hypothesis in the most often used model of ET, harmaline‐induced tremor in rats. Fifty‐four male Wistar rats were randomly distributed into three groups: experimental (EG), surgical control (SCG), and pharmacological control (PCG) groups. EG animals underwent stereotactic unilateral posterior striatotomy. SCG rats underwent sham lesion at the same target. PCG served exclusively as controls for harmaline effects. All animals received, postoperatively, intraperitoneal harmaline, and the induced tremor was video‐recorded for later evaluation by a blind observer. Thirteen animals were excluded from the study. Limb tremor was reduced ipsilaterally to the operation in 20 of 21 rats of EG and in two of nine of SCG, being asymmetric in one of 10 of PCG rats. Comparisons between EG × SCG and EG × PCG were statistically significant, but not between SCG × PCG. Limb tremor reduction was greater in anterior than in posterior paws. Lateral lesions yielded better results than medial lesions. These results suggest that the posterior striatum is involved with harmaline‐induced tremor in rats and support the hypothesis presented. © 2013 Wiley Periodicals, Inc.  相似文献   
93.
This study was designed to investigate the potential neuroprotective effect of exercise in a mouse model of Alzheimer’s disease (AD) induced by intracerebroventricular (i.c.v.) injection of beta-amyloid1–40 (Aβ1–40) peptide. For this aim, male Swiss Albino mice were submitted to swimming training (ST) with progressive increase in intensity and duration for 8 weeks before Aβ1–40 administration (400 pmol/animal; 3 μl/site, i.c.v. route). The cognitive behavioral, oxidative stress, and neuroinflammatory markers in hippocampus and prefrontal cortex of mice were assessed 7 days after Aβ1–40 administration. Our results demonstrated that ST was effective in preventing impairment in short- and long-term memories in the object recognition test. ST attenuated the increased levels of reactive species and decreased non-protein thiol levels in hippocampus and prefrontal cortex induced by Aβ1–40. Also, Aβ1–40 inhibited superoxide dismutase activity and increased glutathione peroxidase, glutathione reductase, and glutathione S-transferase activities in hippocampus and prefrontal cortex—alterations that were mitigated by ST. In addition, ST was effective against the increase of tumor necrosis factor-alpha and interleukin-1 beta levels and the decrease of interleukin-10 levels in hippocampus and prefrontal cortex. This study confirmed the hypothesis that exercise is able to protect against some mechanisms of Aβ1–40-induced neurotoxicity. In conclusion, we suggest that exercise can prevent the cognitive decline, oxidative stress, and neuroinflammation induced by Aβ1–40 in mice supporting the hypothesis that exercise can be used as a non-pharmacological tool to reduce the symptoms of AD.  相似文献   
94.
95.
The notable evolution of heart transplant (HTX) has paralleled the capacity of diagnosing rejection and, consequently, initiating timely treatment. Acute cellular rejection, diagnosed by endomyocardial biopsy, is the most frequent in the first 6 months after HTX. HLA matching is not routinely performed in HTX due to the absence of consensus regarding its usefulness. However, the use of HLA typing might be underscored if it could predict an increased risk of rejection. Therefore, the aim of this study was to evaluate, at a public cardiology center in Brazil, the association between HLA mismatches and the incidence of acute cellular rejection in the first 6 months after HTX. Data were obtained from hospital records and from the National Transplant System. Overall, there was no association between the number of HLA mismatches and the frequency of acute cellular rejection, but there was a tendency toward a higher incidence of rejection with HLA‐DR incompatibility.  相似文献   
96.
Objectives: To compare nitric oxide (NO) serum levels in women with and without preeclampsia. Methods: 106 women were classified into preeclampsia group (n = 40) and normotensive group (n = 66). NO content was measured in the serum. Clinical and laboratorial data were recorded for comparison. Results: Preeclampsia presented a significant increase in nitrate and NOx levels compared to the control group. Uric acid, gestational age, systolic and diastolic blood pressure, and creatinine showed correlation with nitrates and NOx. Conclusion: Increase of NO was observed in preeclampsia women. Failure in the mechanism of action, dependent on cyclic GMP, may justify this finding.  相似文献   
97.
98.
This study aims at quantifying through electromyography the actions of the biceps brachii-BB (long head), triceps brachii-TB (long head) and deltoideus-DA (clavicular portion) muscles, during the going (G) and return (R) phases in "back support" exercises. Surface electrodes were placed at the muscles, according to DELAGI (1981). It was used a specific software and a A/D plate to take the signals. After being collected, the records were processed resulting in efficient values (RMS), were normalized by maximum isometric contraction (MVIC = 100%) and statistically analysed using the Friedman, DSM and Wilcox non-parametric tests. All the muscles presented electromyographic activity of the movements. The triceps brachii was the muscle with higher activity in both phases of the movement. It was concluded that the exercise is indicated for the arm muscle strength development.  相似文献   
99.
The aim of this study was to evaluate the antimicrobial activity of different trademarks and compositions of gutta-percha points and calcium hydroxide pastes used in endodontic therapy. The evaluated material consisted of gutta-percha points containing calcium hydroxide (Roeko), gutta-percha points containing chlorhexidine (Roeko), two conventional gutta-percha points (Endo Points and Roeko) and two calcium hydroxide pastes (Calen and Calen/PMCC). Antimicrobial tests included five species of microorganisms: Escherichia coli (ATCC10538), Staphylococcus epidermidis (ATCC12228), Staphylococcus aureus (ATCC6538), Pseudomonas aeruginosa (ATCC27853), and Micrococcus luteus (ATCC9341). The Agar diffusion method was employed. The plates were kept at room temperature for 2 h for prediffusion and then incubated at 37 degrees C for 24 h. The triphenyltetrazolium chloride gel was added for optimization and the zones of inhibition were measured. Statistical evaluation was carried out using analysis of variance and Tukey Test. The obtained results showed that all microbial species used in the study were inhibited by the gutta-percha points containing chlorhexidine and by the calcium hydroxide pastes (Calen and Calen/PMCC), with similar results (p > 0.05). No antimicrobial activity was observed for the other groups. It was concluded that the gutta-percha points containing chlorhexidine presented antimicrobial activity, whereas the gutta-percha points containing calcium hydroxide did not.  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