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   3155篇
  免费   251篇
  国内免费   24篇
耳鼻咽喉   50篇
儿科学   71篇
妇产科学   140篇
基础医学   525篇
口腔科学   48篇
临床医学   382篇
内科学   657篇
皮肤病学   111篇
神经病学   257篇
特种医学   102篇
外科学   281篇
综合类   69篇
预防医学   162篇
眼科学   76篇
药学   246篇
中国医学   16篇
肿瘤学   237篇
  2023年   19篇
  2022年   36篇
  2021年   92篇
  2020年   57篇
  2019年   91篇
  2018年   103篇
  2017年   88篇
  2016年   79篇
  2015年   122篇
  2014年   147篇
  2013年   194篇
  2012年   253篇
  2011年   272篇
  2010年   169篇
  2009年   144篇
  2008年   222篇
  2007年   196篇
  2006年   175篇
  2005年   152篇
  2004年   136篇
  2003年   116篇
  2002年   95篇
  2001年   72篇
  2000年   41篇
  1999年   63篇
  1998年   29篇
  1997年   19篇
  1996年   14篇
  1995年   7篇
  1994年   14篇
  1993年   6篇
  1992年   12篇
  1991年   21篇
  1990年   20篇
  1989年   15篇
  1988年   27篇
  1987年   16篇
  1986年   16篇
  1985年   10篇
  1984年   16篇
  1983年   4篇
  1981年   5篇
  1980年   5篇
  1979年   8篇
  1978年   4篇
  1977年   4篇
  1975年   3篇
  1974年   5篇
  1971年   4篇
  1969年   2篇
排序方式: 共有3430条查询结果,搜索用时 0 毫秒
41.
The authors compared the postoperative speech and swallowing function of six patients who underwent free radial forearm flap reconstruction after hemiglossectomy with that of six control patients who underwent primary closure of the defect. Clinical speech pathologic evaluations included the Fletcher time-to-time maximum repetition rate of syllables, multiple rhyme test, and overall quality and intelligibility of the patients' speech. Evaluation of swallowing included the duration of deglutition, bolus volume, and ingestion rate. Speech quality, including intelligibility and articulation, was better in patients with primary closure. However, the bolus volume and ingestion rate in deglutition were better in those with flap reconstruction. These results suggest that the flap adds bulk, thus improving pharyngeal clearance by maintaining the tongue-to-mouth roof contact that is necessary in the swallowing process. The nonfunctional flap, however, hinders articulation by restricting the mobility of the remaining portion of the normal tongue.  相似文献   
42.
OBJECTIVE: We wanted to investigate the utility of performing fiberoptic bronchoscopy before bronchial artery embolization in patients with massive hemoptysis. MATERIALS AND METHODS: We retrospectively reviewed the cases of all patients with hemoptysis who had presented at either of two local hospitals, one county hospital and one community hospital, between 1988 and 2000 and who had undergone fiberoptic bronchoscopy before bronchial arteriography. All data were abstracted using a standardized coding form, and radiographs were independently reviewed by two of the authors. RESULTS: Twenty-nine patients meeting the inclusion criteria were identified; one patient was excluded because of missing radiographs. The remaining 28 patients consisted of 19 men and nine women, with an average age of 54.6 years (age range, 16-91 years). The clinically determined diagnoses of their symptoms were tuberculous bronchiectasis (n = 14; 50.0%); bronchogenic carcinoma (n = 4; 14.3%); active tuberculosis (n = 2; 7.1%); nontuberculous bronchiectasis (n = 2; 7.1%); active coccidioidomycosis, pancreaticobronchial fistula, arteriovenous malformation, and tetralogy of fallot (n =1 each; 3.6% each); and unknown cause (n = 2; 7.1%). The bleeding site determined through bronchoscopy was consistent with that determined through radiographs in 23 patients (82.1%); all had either unilateral disease (n = 15), bilateral disease with unilateral cavities (n = 5), or a preponderance of disease on one side (n = 3). Bronchoscopy was an essential tool in determining the bleeding site in only three patients (10.7%), all of whom had bronchiectasis without localizing features visible on chest radiographs. In the remaining two patients (7.1%), bronchoscopic findings were indeterminate, but radiographs were helpful. CONCLUSION: Fiberoptic bronchoscopy before bronchial artery embolization is unnecessary in patients with hemoptysis of known causation if the site of bleeding can be determined from radiographs and no bronchoscopic airways management is needed.  相似文献   
43.
BACKGROUND: Earlier phase 1 and 2 studies have shown that regadenoson has desirable features as a stress agent for myocardial perfusion imaging. METHODS AND RESULTS: This multicenter, double-blinded phase 3 trial involved 784 patients at 54 sites. Each patient underwent 2 sets of gated single photon emission computed tomography myocardial perfusion imaging studies: an initial qualifying study with adenosine and a subsequent randomized study with either regadenoson (2/3 of patients) or adenosine. Regadenoson was administered as a rapid bolus (<10 seconds) of 400 mug. The primary endpoint was to demonstrate noninferiority by showing that the difference in the strength of agreement in detecting reversible defects, based on blinded reading, between sequential adenosine-regadenoson images and adenosine-adenosine images, lay above a prespecified noninferiority margin. Other prospectively defined safety and tolerability comparisons and supporting analyses were also performed. The average agreement rate based on the median of 3 independent blinded readers was 0.63 +/- 0.03 for regadenoson-adenosine and 0.64 +/- 0.04 for adenosine-adenosine-a 1% absolute difference with the lower limit of the 95% confidence interval lying above the prespecified noninferiority margin. Side-by-side interpretation of regadenoson and adenosine images provided comparable results for detecting reversible defects. The peak increase in heart rate was greater with regadenoson than adenosine, but the blood pressure nadir was similar. A summed symptom score of flushing, chest pain, and dyspnea was less with regadenoson than adenosine (P = .013). CONCLUSIONS: This phase 3 trial shows that regadenoson provides diagnostic information comparable to a standard adenosine infusion. There were no serious drug-related side effects, and regadenoson was better tolerated than adenosine.  相似文献   
44.
BackgroundOrbital compartment syndrome (OCS) is an ocular emergency that can severely threaten the visual potential. The most common etiologies include facial trauma-related orbital wall fractures and postoperative bleeding within the orbit. Nontraumatic cases were also reported sporadically, although they are rare. The orbital volume limits the compliance to expand when space-occupying lesions develop. Both direct compression of the optic nerve and depleted perfusion from elevated intraorbital pressure subsequently lead to ischemic optic neuropathy and vision loss.Case ReportA 74-year-old man experienced headache, bulging left eye, dull pain, vision loss, nausea, and vomiting within 1 day. Computed tomography and magnetic resonance imaging revealed a heterogeneous mass extending from the orbital apex and connected with the ophthalmic vein. Lateral canthotomy and cantholysis were performed at bedside for emergent orbital decompression. The proptosis and pain relieved after surgery, but visual loss remained irreversible. Surgical exploration was conducted and pathology proved the diagnosis of varix of the ophthalmic vein with thrombosis.Why Should an Emergency Physician Be Aware of This?Clinicians should be aware of the presentation of OCS and perform timely orbital decompression, which could reverse visual impairment. These patients might also benefit from immediate consultants with ophthalmologists and radiologists.  相似文献   
45.
ObjectivePreterm infants receive long-term parenteral nutrition (PN) for gastrointestinal immaturity. This study aimed to determine if mixed lipid emulsions containing fish oil decrease the incidence of PN-associated cholestasis by reducing oxidative stress and providing an anti-inflammatory effect.MethodsThis retrospective cohort study enrolled 399 very low birth weight premature infants (gestational age ≤32 weeks) between January 2009 and November 2017 at a single neonatal intensive care unit. Preterm infants received total PN with either mixed lipid emulsion including fish oil (SMOFlipid®, n = 195) or soybean oil-based lipid emulsion (Lipovenoes®, n = 204) for at least 7 days. We compared the outcomes of PN-associated cholestasis, comorbidities, and mortality between the groups.ResultsThe incidence of PN-associated cholestasis was significantly lower in the SMOFlipid group than in the Lipovenoes group. The duration to full feeding days was significantly shorter in the SMOFlipid group compared with the Lipovenoes group. Relevant complications, such as severe retinopathy of prematurity and bronchopulmonary dysplasia, were also significantly reduced in the SMOFlipid group compared with the Lipovenoes group.ConclusionIn premature infants, PN with fish oil-based lipid emulsions is associated with a lower incidence of PN-associated cholestasis compared with soybean oil-based lipid emulsions.  相似文献   
46.
47.
48.
Glomus tumors (GT) have been classified among tumors of perivascular smooth muscle differentiation, together with myopericytoma, myofibroma/tosis, and angioleiomyoma, based on their morphologic overlap. However, no molecular studies have been carried out to date to investigate their genetic phenotype and to confirm their shared pathogenesis. RNA sequencing was performed in three index cases (GT1, malignant GT; GT2, benign GT and M1, multifocal myopericytoma), followed by FusionSeq data analysis, a modular computational tool developed to discover gene fusions from paired‐end RNA‐seq data. A gene fusion involving MIR143 in band 5q32 was identified in both GTs with either NOTCH2 in 1p13 in GT1 or NOTCH1 in 9q34 in GT2, but none in M1. After being validated by FISH and RT‐PCR, these abnormalities were screened on 33 GTs, 6 myopericytomas, 9 myofibroma/toses, 18 angioleiomyomas and in a control group of 5 sino‐nasal hemangiopericytomas. Overall NOTCH2 gene rearrangements were identified in 52% of GT, including all malignant cases and one NF1‐related GT. No additional cases showed NOTCH1 rearrangement. As NOTCH3 shares similar functions with NOTCH2 in regulating vascular smooth muscle development, the study group was also investigated for abnormalities in this gene by FISH. Indeed, NOTCH3 rearrangements were identified in 9% of GTs, all present in benign soft tissue GT, one case being fused to MIR143. Only 1/18 angioleiomyomas showed NOTCH2 gene rearrangement, while all the myopericytomas and myofibroma/toses were negative. In summary, we describe novel NOTCH1–3 rearrangements in benign and malignant, visceral, and soft tissue GTs. © 2013 Wiley Periodicals, Inc.  相似文献   
49.
Located in tropical and subtropical region, Taiwan is an island with high algal species diversity. In this study, a number of fungal strains were isolated from marine macroalgae collected from northeastern intertidal zone of Taiwan. Preliminary anti-inflammatory screening has shown that the methanolic extracts of solid fermented products of the red alga Mastophora rosea-derived fungal strain Acremonium sp. NTU492 exhibited significant bioactivity. In an attempt to disclose the active principles from this fungal strain, a series of separation and purification was thus undertaken, which has led to the isolation and characterization of seven compounds including four new peptides, namely acrepeptins A–D (1–4), along with previously reported destruxin B (5), guangomide A (6), and guangomide B (7). Their structures were elucidated by spectroscopic analysis and compared with literatures. Of these, acrepeptins A (1) and C (3) showed markedly inhibitory activities on nitric oxide production in lipopolysaccharide-activated microglial BV-2 cells with IC50 values of 12.0 ± 2.3 and 10.6 ± 4.0 μM, respectively. Furthermore, acrepeptins A (1) and C (3) significantly attenuated the expression of inducible nitric oxide synthase in a concentration-dependent manner (5–40 μM).  相似文献   
50.
The occurrence of leiomyoma of the colon is uncommon. Most of these lesions are clinically silent and are found incidentally during laparotomy or endoscopic procedures for unrelated conditions. Symptomatic leiomyomas of the colon are encountered less frequently, with only sporadic reports in the literatures. We describe a heretofore unreported case of a large extraluminal leiomyoma of the sigmoid colon presenting as massive lower gastrointestinal hemorrhage. Because it was extraluminal in position, it was difficult to make an accurate diagnosis endoscopically and the condition was easily misdiagnosed as angiodysplasia of the colon until CT scan results were seen. Although rare and benign in nature, leiomyoma of the colon may cause life-threatening complications that require emergency surgery and should be included in the differential diagnosis of lower gastrointestinal hemorrhage.  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