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   750篇
  免费   35篇
  国内免费   8篇
耳鼻咽喉   16篇
儿科学   14篇
妇产科学   34篇
基础医学   57篇
口腔科学   15篇
临床医学   66篇
内科学   190篇
皮肤病学   10篇
神经病学   89篇
特种医学   19篇
外科学   163篇
综合类   10篇
预防医学   19篇
眼科学   38篇
药学   27篇
中国医学   1篇
肿瘤学   25篇
  2023年   1篇
  2022年   9篇
  2021年   17篇
  2020年   10篇
  2019年   21篇
  2018年   13篇
  2017年   12篇
  2016年   23篇
  2015年   20篇
  2014年   17篇
  2013年   37篇
  2012年   55篇
  2011年   63篇
  2010年   45篇
  2009年   29篇
  2008年   49篇
  2007年   44篇
  2006年   53篇
  2005年   56篇
  2004年   53篇
  2003年   46篇
  2002年   34篇
  2001年   6篇
  2000年   18篇
  1999年   6篇
  1998年   5篇
  1997年   5篇
  1996年   7篇
  1995年   5篇
  1994年   1篇
  1993年   1篇
  1992年   4篇
  1991年   5篇
  1990年   2篇
  1989年   5篇
  1988年   1篇
  1987年   3篇
  1983年   1篇
  1979年   1篇
  1974年   2篇
  1973年   3篇
  1971年   3篇
  1970年   1篇
  1969年   1篇
排序方式: 共有793条查询结果,搜索用时 31 毫秒
1.
Background and aims The aim of this study was to assess the diagnostic value of image guided percutaneous fine needle aspiration (FNA) biopsy in equivocal mediastinal masses.Patients Sixty-six patients with an equivocal mediastinal mass who underwent FNA biopsy between 1993 and 2003 were eligible for final analysis. The cytological and definitive diagnosis of masses were grouped as primary 22 (33%)−30 (46%) and secondary (metastatic) neoplasms 18 (27%)−18 (27%) and nonneoplastic lesions 20 (30%)−18 (%27) respectively.Results The diagnostic accuracy (%95 C.I.) of FNA biopsy for primary mediastinal neoplasms, secondary neoplasms and nonneoplastic lesions were found to be 93.3 (83.8–98.2)%, 100 (95.1–100)%, 93.3 (83.8–98.2)%, respectively.Conclusion Image guided percutaneous FNA biopsy is a safe and highly accurate diagnostic method for equivocal mediastinal masses.  相似文献   
2.
Extracorporeal septoplasty is a radical solution for the severely deviated nose. The major problems associated with this procedure are fixation of the septal cartilage graft and dorsal irregularities. Extracorporeal septoplasty was performed in combination with open rhinoplasty in 17 patients with severe nasal deformities. In this technique septum was totally removed through the columellar incision of open rhinoplasty, corrected outside, and replaced as a free ``L' shaped cartilage graft. The cartilage graft was fixated to the upper lateral cartilages to restore the natural relations of the anatomical structures. Additional rhinoplastic manipulations were also performed. The follow-up period was up to 18 months. The overall result was successful in all patients. Nasal deviation did not recur and secondary revisions were not needed for any patient during follow-up.  相似文献   
3.
1. The cells of the cortex of the posterior bank of the superior temporal sulcus of the monkey appear to be specialized to signal motion in the visual field. In this paper, cells in this cortical area capable of signalling motion towards or away from the animal are described.2. Two such types of cell were encountered. One type, the opposed movement complex and opposed movement hypercomplex cells, responded to two edges at a given orientation moving towards or away from each other within the receptive fields. These cells were driven either monocularly or binocularly, but when binocularly driven the cells responded in an identical manner to stimulation of each eye, thus suggesting that such cells must receive a double, and opposed, input from each eye. The other type of cell, always binocularly driven, responded to movement in opposite directions on the two retinas, thus suggesting that such cells must receive diametrically opposite connexions from the two eyes.3. Long penetrations made to study the manner in which such cells were grouped together in the cortex revealed that they were arranged in small groups or clusters, separated from each other by the common directionally selective cells so prominently present in this area. Thus, cells with one type of wiring mechanism were separated from each other by cells receiving another, and more common, type of anatomical wiring.  相似文献   
4.
In this study, we sought to determine whether sperm DNA fragmentation (DFI%) and high DNA stainability (HDS%) evaluated by sperm chromatin structure assay (SCSA) predict recurrent implantation failure (RIF) or pregnancy rate. A retrospective study was performed of consecutive cycles of ICSI treatment from 2009 to 2018. A total of 386 couples that underwent 1,216 frozen embryo transfer (FET) cycles were analysed. Mean female and male age was 34 ± 3.6 years and 37.3 ± 6.6 years, respectively, and a median total motile sperm count (TMSC) was 43.5 [9.9–105.5] million. Overall median DFI% and HDS% was 12 [7.1–18.9] and 9.6 [6.5–14.4] respectively. On multivariable analysis, DFI% and HDS% were not associated with RIF (DFI%: OR = 1.01, 95% CI: 0.98–1.04, p = .414; HDS%: OR = 0.97, 95% CI: 0.94–1.01, p = .107) or IVF success, defined as clinical pregnancy (DFI%: OR = 1.00, 95% CI: 0.99–1.01, p = .641; HDS%: OR = 1.01, 95% CI: 0.99–1.02, p = .565). We found that neither DFI% or HDS%, as assessed by SCSA, were predictive of RIF or pregnancy rate. This finding suggests that sperm DNA fragmentation does not predict RIF or pregnancy rate.  相似文献   
5.
Mycobacterium tuberculosis (H(37)R(v))-infected guinea-pig model was used to investigate the effect of water extract of propolis (WEP). After subcutaneous inoculation of tubercle bacilli, each animal received oral WEP (n=9), isoniazid (n=5) or saline (n=6) as placebo and were sacrificed 30 days later. Formation of necrosis was less prominent in the group treated with WEP, but was not statistically significant (P>0.05). The granuloma formation in the same group was more prominent than the placebo and isoniazid groups; however, this finding failed to reach statistical significance by the Kruskal-Wallis test (P>0.05). These findings suggest that Turkish WEP may have a limited effect on the development of tuberculosis infection in this guinea-pig model.  相似文献   
6.
The aim of this study is to evaluate the impact of ovarian reserve and age of women on early morphokinetic parameters of embryos with a time-lapse monitoring system. In total, 197 infertile couples with poor ovarian reserve (Group 1, n?=?41), normal ovarian reserve (Group 2, n?=?59), or polycystic ovaries (Group 3, n?=?97) were included. The time from insemination to the following events were analyzed: pronuclear fading (Pnf) and cleavage to 2, 3, 4 and 5 cells. The optimal ranges for morphokinetic parameters of t5, s2 and cc2 in each group were also evaluated. In total, 1144 embryos were evaluated. Morphokinetic parameters did not differ statistically between the groups. Data were analyzed according to different age groups (20–30, 30–40,?>40). The morphokinetic parameters did not differ statistically in Group 1 and 3. In Group 2, the times from insemination to tPnf, t2, t3, t4 were significantly shorter in the younger age group than the older age group (p?相似文献   
7.
8.
9.
BACKGROUND: Helicobacter pylori eradication rates have tended to decrease recently possibly related with increasing antibiotic resistance. The present study investigated the efficacy of three different ranitidine bismuth citrate (RBC) based triple regimens in a population with high prevalence of H. pylori. METHODS: 300 consecutive H. pylori positive patients with non-ulcer dyspepsia were randomized into three regimens: (1) RBC 400 mg, amoxicillin 1000 mg and tetracycline 500 mg [RBC-AT], (2) RBC 400 mg, amoxicillin 1000 mg and clarithromycin 500 mg [RBC-AC], (3) RBC 400 mg, metronidazole 500 mg and tetracycline 500 mg [RBC-MT]. Tetracycline was given q.i.d, all other drugs were given b.i.d. for 14 days. Gastroscopy and (14)C-Urea breath test (UBT) were performed before enrollment and UBT only was repeated 6 weeks after the end of treatment. RESULTS: 274 patients completed the protocols. The overall 'intention to treat' and 'per protocol' H. pylori eradication rates in all subjects were 57.6% (95% CI: 52-63) and 63.1% (95% CI: 57-68), respectively. The eradication rates achieved in the groups (RBC-AT, RBC-AC and RBC-MT) were 64.4% (95% CI: 54-74), 66.2% (95% CI: 56-76), and 58.9% (95% CI: 49-68) on 'per protocol' analyses, respectively. There was no difference in eradication rates, compliance and major side effects between the groups. CONCLUSION: The current RBC-based H. pylori eradication therapy is not adequately effective.  相似文献   
10.
BackgroundNon-dipper blood pressure is defined by less than a 10% reduction in nighttime blood pressure, and it is associated with cardiovascular disease. Inflammation is thought to play a role in the pathogenesis of both chronic obstructive pulmonary disease (COPD) and non-dipper blood pressure pattern, and both diseases are associated with lower quality of life.ObjectiveThe aim of this study was to investigate the effects of non-dipper blood pressure pattern in patients with COPD.MethodsA cross-sectional study was carried out with 142 patients with COPD. The Saint George Respiratory Questionnaire and the Euro Quality of Life Scale were used to collect data. To understand arterial stiffness, the augmentation index and pulse wave velocity were measured, and 24-hour ambulatory blood pressure monitoring was subsequently performed. A multivariable logistic regression model was used to understand the relationship between different independent variables and blood pressure pattern. P values lower than 0.05 were considered statistically significant.ResultsAs a result, 76.1% (n = 108) of the patients had non-dipper blood pressure pattern. Non-dipper patients had higher C-reactive protein (OR:1.123; 95% CI:1.016;1.242), augmentation index (OR: 1.057; 95% CI: 1.011;1.105) and Saint George Respiratory Questionnaire total score (OR: 1.021; 95% CI: 1.001;1.042) than dipper patients. Also, as the number of people living at home increased, non-dipper blood pressure pattern was found to be more frequent (OR: 1.339; 95% CI: 1.009;1.777).ConclusionNon-dipper blood pressure pattern may increase cardiovascular risk by triggering inflammation and may adversely affect the prognosis of COPD by lowering the disease-related quality of life. (Arq Bras Cardiol. 2020; [online].ahead print, PP.0-0)  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