全文获取类型
收费全文 | 5282篇 |
免费 | 266篇 |
国内免费 | 53篇 |
专业分类
耳鼻咽喉 | 104篇 |
儿科学 | 185篇 |
妇产科学 | 141篇 |
基础医学 | 505篇 |
口腔科学 | 130篇 |
临床医学 | 466篇 |
内科学 | 1161篇 |
皮肤病学 | 123篇 |
神经病学 | 246篇 |
特种医学 | 342篇 |
外科学 | 894篇 |
综合类 | 156篇 |
一般理论 | 4篇 |
预防医学 | 343篇 |
眼科学 | 193篇 |
药学 | 333篇 |
中国医学 | 16篇 |
肿瘤学 | 259篇 |
出版年
2023年 | 37篇 |
2022年 | 82篇 |
2021年 | 180篇 |
2020年 | 84篇 |
2019年 | 120篇 |
2018年 | 140篇 |
2017年 | 108篇 |
2016年 | 146篇 |
2015年 | 174篇 |
2014年 | 202篇 |
2013年 | 278篇 |
2012年 | 335篇 |
2011年 | 367篇 |
2010年 | 209篇 |
2009年 | 188篇 |
2008年 | 313篇 |
2007年 | 339篇 |
2006年 | 316篇 |
2005年 | 322篇 |
2004年 | 255篇 |
2003年 | 249篇 |
2002年 | 200篇 |
2001年 | 74篇 |
2000年 | 81篇 |
1999年 | 78篇 |
1998年 | 53篇 |
1997年 | 47篇 |
1996年 | 43篇 |
1995年 | 27篇 |
1994年 | 33篇 |
1993年 | 23篇 |
1992年 | 29篇 |
1991年 | 28篇 |
1990年 | 34篇 |
1989年 | 33篇 |
1988年 | 32篇 |
1987年 | 24篇 |
1986年 | 34篇 |
1985年 | 21篇 |
1984年 | 21篇 |
1983年 | 20篇 |
1981年 | 13篇 |
1980年 | 14篇 |
1979年 | 14篇 |
1978年 | 18篇 |
1975年 | 12篇 |
1974年 | 20篇 |
1973年 | 20篇 |
1972年 | 16篇 |
1971年 | 12篇 |
排序方式: 共有5601条查询结果,搜索用时 15 毫秒
111.
The combination of high-dose busulfan (16 mg/kg) and 200 mg/kg cyclophosphamide is gaining increasing significance as a preparative regimen prior to autologous, syngeneic, or allogeneic marrow transplantation. A new regimen of high-dose busulfan in conjunction with a reduced dose of 120 mg/kg cyclophosphamide has recently been described as a preparative regimen prior to allogeneic transplantation. To determine the drug-related nonhematologic toxic effects of this new regimen without confounding factors associated with allogeneic transplantation, we conducted a pilot study using this new regimen in 20 patients with acute myeloid leukemia (AML) in first remission prior to autologous unpurged marrow transplantation. All patients experienced transient non-life-threatening acute drug-related toxicity with skin reactions in 20 (100%), nausea and vomiting in 20 (100%), oral mucositis in 18 (90%), hepatic functional impairment in 17 (85%), hemorrhagic cystitis in three (15%), and generalized seizures in two (10%) of these patients, respectively. Two procedural, fatal complications resulted from infectious causes that were not directly related to the speed of hematopoietic reconstitution or the toxicity of the preparative regimen. The 3-year event-free survival estimate (55% +/- 11%) and probability of leukemic recurrence (38% +/- 11%) attained with this new regimen in recipients of autografts in first remission of AML are promising and challenge comparisons with preparative regimens employing combinations of cytotoxic agents or total body irradiation (TBI). 相似文献
112.
Fatma E. Akin Cenk Sari Sevil ?zer-Sari Aylin Demirezer-Bolat Tahir Durmaz Telat Keles Osman Ersoy Engin Bozkurt 《Saudi Journal Of Gastroenterology》2016,22(2):116-121
Background/Aim:
The aim of this study was to investigate the effects of celiac disease on cardiac functions using tissue Doppler echocardiography (TDE).Patients and Methods:
The study included 30 patients with celiac disease (CD) and 30 healthy volunteers. Echocardiographic examinations were assessed by conventional echocardiography and tissue Doppler imaging. The peak systolic velocity (S''m), early diastolic myocardial peak velocity (E''m), late diastolic myocardial peak velocity (A''m), E''m/A''m ratio, myocardial precontraction time (PCT''m), myocardial contraction time (CT''m), and myocardial isovolumetric relaxation time (IVRT''m), E to E''m ratio were measured.Results:
In pulsed wave Doppler echocardiography, mitral late diastolic flow (A) velocity and E to E''m ratio were significantly higher (P = 0.02 and P = 0,017), E/A ratio was significantly lower (P = 0.008) and IVRT was significantly prolonged (P = 0.014) in patients with CD. In TDE, S''m, E''m, and E''m/A''m ratio were significantly lower, IVRT''m was longer (P = 0.009) from septal mitral annulus and S''m, E''m, E''m/A''m ratio were significantly lower, PCT''m, PCT/ET ratio, IVRT''m were longer, and MPI was higher from lateral mitral annulus in celiac group than controls.Conclusion:
Our study confirms that patients with CD have impaired diastolic function. More importantly, we also demonstrated an impairment of myocardial systolic function in patients with CD by TDE. We recommend using TDE in addition to conventional echocardiography parameters for the cardiovascular risk assessment of patients with CD. 相似文献113.
Effect of diurnal variability of heart rate on development of arrhythmia in patients with chronic obstructive pulmonary disease 总被引:4,自引:0,他引:4
Tükek T Yildiz P Atilgan D Tuzcu V Eren M Erk O Demirel S Akkaya V Dilmener M Korkut F 《International journal of cardiology》2003,88(2-3):199-206
We examined the possible effect of diurnal variability of heart rate on the development of arrhythmias in patients with chronic obstructive pulmonary disease (COPD). Forty-one COPD patients (M/F: 39/2, mean age: 59+/-8.5 years) and 32 (M/F: 27/5, mean age: 57+/-11 years) healthy controls were included. Twenty-four hour ECG recordings were analyzed for atrial fibrillation (AF) or ventricular premature beats (VPB), and circadian changes in heart rate variability (HRV) were assessed by dividing the 24-h period into day-time (08:00-24:00 h) and night-time (24:00-08:00 h) periods. Night-time total (TP), low frequency (LF) and high frequency (HF) powers were similarly lower from day-time parameters in AF(-) COPD patients (HF 3.91+/-1 vs. 4.43+/-1.04 ms(2), P=0.001) and controls (HF 3.95+/-0.72 vs. 4.82+/-0.66 ms(2), P<0.001). The LF/HF ratios were also significantly reduced in the same patient groups (AF(-) COPD 1.35+/-0.21 vs. 1.27+/-0.19, P=0.04, controls 1.43+/-0.14 vs. 1.24+/-0.09, P<0.001). Night-time TP and LF were increased, HF unchanged and LF/HF significantly increased (1.11+/-0.25 vs. 1.19+/-0.27, P<0.05) in AF(+) COPD patients. Frequency of VPB was correlated with corrected QT dispersion (QTc(d)) (r=0.52, P=0.001) and the day-time/night-time HF ratio (r=0.43, P=0.02). Patients with QTc(d)>or=60 ms did not have the expected increase in night-time HF and had a statistically insignificant increase in LF/HF ratio. In COPD patients with QTc(d)<60 ms, circadian changes in HRV parameters were parallel with the controls. We concluded that COPD patients with arrhythmia had circadian HRV disturbances such as unchanged night-time parasympathetic tone and disturbed sympatho-vagal balance in favor of the sympathetic system all day long, which may explain the increased frequency of arrhythmia. 相似文献
114.
115.
Osman Ekinci Süheyla Abitagaoglu Güldem Turan Zübeyir Sivrikaya Gül?en Bosna Asu ?zgultekin 《Saudi medical journal》2015,36(4):432-436
Objectives:
To compare the insertion time, ease of device insertion, ease of gastric tube insertion, airway leakage pressure, and complications between the laryngeal mask airway (LMA) ProSeal (P-LMA) and I-gel (I-gel) groups.Methods:
Eighty patients with age range 18-65 years who underwent elective surgery were included in the study. The study took place in the operation rooms of Haydarpaşa Numune Hospital, Istanbul, Turkey from November 2013 to April 2014. Patients were equally randomized into 2 groups; the I-gel group, and the P-LMA group. In both groups, the same specialist inserted the supraglottic airway devices. The insertion time of the devices, difficulty during insertion, difficulty during gastric tube insertion, coverage of airway pressure, and complications were recorded.Results:
The mean insertion time in the I-gel group was significantly lower than that of the P-LMA group (I-gel: 8±3; P-LMA: 13±5 s). The insertion success rate was higher in the I-gel group (100%, first attempt) than in the P-LMA group (82.5%, first attempt). The gastric tube placement success rate was higher in the I-gel group (92.5%, first attempt) than in the P-LMA group (72.5%, first attempt). The airway leakage pressures were similar.Conclusion:
Insertion was easier, insertion time was lower, and nasogastric tube insertion success was higher with the I-gel application, and is, therefore, the preferred LMA.Laryngeal mask airways (LMA) represent a good alternative to endotracheal intubation in suitable cases. The LMAs are used to provide ventilation, or to ease the insertion of an endotracheal tube (TT) in difficult airways, but they are also becoming more frequently used to reduce TT associated complications.1 In particular, the recently developed models of LMAs, which include a gastric tube, have become more commonly preferred in anesthesia applications.2 The I-gel (I-gel) (Intersurgical Ltd, Workingham, UK) has a latex-free, non-inflatable, gel-like, thermoplastic elastomeric cuff that provides easy coverage by properly fitting the anatomy of the supraglottic region and also involves a gastric tube; therefore, it has become more frequently used in patients under general anesthesia and receiving positive pressure ventilation.3 It has been reported that the single-use, inflatable cuff-free I-gel can be inserted more easily and has a reduced morbidity rate.4,5 It is recommended in emergency cases requiring intubation, and particularly in airway management of cases experiencing cardiopulmonary arrest.6 Another supraglottic airway device that enables gastric aspiration is the LMA ProSeal (Laryngeal Mask Company Ltd, Berkshire, UK). Since it is a semi-rigid device with an inflatable cuff, it has been reported to cause mucosa and nerve damage in the supraglottic region, sore throat, and hoarseness due to the cuff pressure.7The present study aimed to compare the I-gel and the LMA ProSeal (P-LMA) with respect to the duration of insertion, ease of insertion, airway pressure leakage, gastric tube insertion success ratio, and complications. 相似文献116.
Mehmet T. Koylu Gokcen Gokce Yusuf Uysal Osman M. Ceylan Dorukcan Ak?nc?oglu Armagan Gunal 《Saudi medical journal》2015,36(10):1205-1209
Objectives:
To analyze the indications and types of eye removals at a military tertiary care hospital in Turkey.Methods:
The medical records (age, gender, affected eye, type of surgical procedure, indications of surgery) of 123 patients who underwent evisceration and enucleation in the course of a 15-year period (January 2000 to December 2014) at Gulhane Military Medical Academy, Ankara, Turkey were reviewed retrospectively.Results:
The mean age was 35.61±18.52 (range 3-80 years). The number of male in the patient group was 92 (74.8%) and female was 31 (25.2%). Patients who underwent evisceration were 95 (77.2%), whereas 28 (22.8%) of them underwent enucleation. The mean age of the eviscerated patients was 30.63±13.08, whereas the mean age of the enucleated patients was 52.50±23.92 (p<0.001). The leading indications for eye amputations were trauma (n=62, 50.4%), malignancy (n=20, 16.3%), painful blind eye and absolute glaucoma (n=20, 16.3%), endophthalmitis (n=12, 9.7%), and phthisis bulbi, and cosmetic reasons (n=9, 7.3%).Conclusion:
Trauma was the most common etiology for evisceration, and malignancy was the most common etiology for enucleation. Using protective eyewear and early detection of intraocular malignancy and glaucoma through routine ophthalmic examinations are essential for providing non-invasive treatment modalities instead of eye removal.Eye removals are performed in cases of severe trauma, eye malignancy, endophthalmitis unresponsive to medical treatment, painful blind eye, and absolute glaucoma, as well as phthisic eyes with severe cosmetic defects.1-4 Evisceration is the removal of intraocular structures other than the sclera, whereas enucleation is the removal of the entire eyeball including the sclera leaving behind only the orbital structures.5 Evisceration surgery is usually preferred in extremely severe trauma cases, while enucleation is used in advanced cases of intraocular malignancy.1,3,6 The aim in such surgeries is to remove the damaged eye, provide sufficient comfort, replace the lost volume, and renew functional and cosmetic appearance.7 Removal is a difficult decision for both patients and physicians, and is considered as the last resort. In addition to clinical indications, the potential sight of the eye and patient’s psychological aspects should also be taken into consideration.1 In developed countries, the most common reasons for eye amputations are malignancy3 and trauma,6 whereas in developing countries, infections are the dominating factors.1,8 In this study, the etiology and surgery methods of 123 eye amputations performed in the Gulhane Military Medical Academy (GATA) between January 2000 and December 2014 were analyzed, and possible public health and preventive programs regarding this matter were evaluated. 相似文献117.
Ahmed Mousa Altaf A. Kondkar Saleh A. Al-Obeidan Taif A. Azad Tahira Sultan Essam Osman Khaled K. Abu-Amero 《Saudi medical journal》2015,36(6):671-677
Objectives:
To compare the mean total antioxidant status (TAS) among 3 glaucoma types, namely: pseudoexfoliation glaucoma (PEG), primary open angle glaucoma (POAG), and primary angle closure glaucoma (PACG), and study its potential association with various clinical glaucoma-parameters.Methods:
In this case-control study, plasma samples were obtained between September 2013 and October 2014 from 340 glaucoma patients (PEG [n=54]; POAG [n=147]; PACG [n=139]), and 351 controls of matching age, gender, ethnicity, and 5 different systemic co-morbidities from King Abdulaziz University Hospital, Riyadh, Saudi Arabia. The TAS in all samples was determined by a colorimetric-based assay.Results:
The mean±standard deviation of TAS was significantly lower among cases: 0.77±0.32 than controls: 1.1±0.22, p<0.0001. Moreover, the TAS levels were significantly different across the 3 types of glaucoma: 0.86±0.24 in PEG, 0.47±0.32 in POAG, and 0.98±0.41 in PACG (all p<0.0001). In addition, there was a significant correlation between TAS and age at onset (Pearson correlation coefficient [R] 0.17, p<0.0001), cup/disc ratio (R: -0.13, p=0.004), and number of anti-glaucoma medications (R: -0.16, p=0.001).Conclusion:
Our findings provide evidence that plasma TAS levels are decreased in patients with glaucoma, more so in POAG and PEG than PACG, supporting the hypothesis that decreased antioxidative defense and/or increased oxidative stress may have a critical role in the pathogenesis of glaucoma.Glaucoma is a progressive optic neuropathy associated with optic nerve damage, and is one of the most leading cause of blindness worldwide.1 Elevated intraocular pressure (IOP) as a result of reduction in normal aqueous outflow is a major causal risk factor that is well supported by animal studies.2-4 Although IOP is considered a major risk factor for glaucoma,2,3 other concomitant factors affecting the pathophysiology of glaucomatous retinal ganglion cell (RGC) death include retinal ischemia,5 nutritional status,6 and oxidative stress.7 There is evidence of oxidative damage in ocular diseases, such as cataract and age-related macular degeneration.8 In addition, significant oxidative damage has been demonstrated in human trabecular meshwork (TM) cells of patients with glaucoma,7 causing elevated IOP and visual field damage.9 Furthermore, our previous studies have documented mitochondrial abnormalities10-12 (oxidative stress marker), and glutathione-S-transferase (antioxidant) gene (GST) polymorphisms to be associated with various types of glaucoma.13 It is clearly evident from the literature, and our own studies, that oxidative stress mechanisms play a critical role in the pathogenesis of glaucoma. Previous studies had demonstrated reduced total antioxidant capacity in aqueous humor and blood samples from patients with glaucoma.14-17 To evaluate the role of oxidative stress in different types of glaucoma we had previously investigated total antioxidants status (TAS) in the plasma of pseudoexfoliation glaucoma (PEG) patients,18 primary angle closure glaucoma (PACG) patients,19 and in the plasma of primary open angle glaucoma (POAG) patients.20 As an extension to these studies, here, we compare the mean TAS level among these 3 glaucoma types, and study the potential association between the TAS level and various clinical parameters important to each type of glaucoma.18-20 相似文献118.
Hopanoid lipids compose the Frankia vesicle envelope, presumptive barrier of oxygen diffusion to nitrogenase
下载免费PDF全文
![点击此处可从《Proceedings of the National Academy of Sciences of the United States of America》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Berry AM Harriott OT Moreau RA Osman SF Benson DR Jones AD 《Proceedings of the National Academy of Sciences of the United States of America》1993,90(13):6091-6094
Biological nitrogen fixation in aerobic organisms requires a mechanism for excluding oxygen from the site of nitrogenase activity. Oxygen exclusion in Frankia spp., members of an actinomycetal genus that forms nitrogen-fixing root-nodule symbioses in a wide range of woody Angiosperms, is accomplished within specialized structures termed vesicles, where nitrogen fixation is localized. The lipidic vesicle envelope is apparently a functional analogue of the cyanobacterial heterocyst envelope, forming an external gas-diffusion barrier around the nitrogen-fixing cells. We report here that purified vesicle envelopes consist primarily of two hopanoid lipids, rather than of glycolipids, as is the case in cyanobacteria. One envelope hopanoid, bacteriohopanetetrol phenylacetate monoester, is vesicle-specific. The Frankia vesicle envelope thus represents a layer specific to the locus of nitrogen fixation that is biosynthetically uniquely derived. 相似文献
119.
The predictive accuracy of electrocardiographic markers in identifying the infarct-related artery of myocardial infarctions has been a subject of extensive investigation. The present study was designed to test whether the index L II/L III ratio adapted to exercise electrocardiograms could be utilized as a marker to distinguish right coronary and left circumflex arteries as culprit coronaries in acute inferior myocardial infarctions. For this purpose, 82 patients with a positive-symptom-limited and/or submaximal treadmill exercise test with modified Bruce protocol after an acute inferior myocardial infarction were studied. Those patients with ST segment elevation during the stress test were included in the study. ST segment index was defined as the ratio of exercise-induced ST elevation amplitude in L II/L III. Patients were classified as having an index > 1 (n=24) and < 1 (n=58), and the findings were compared with the findings on coronary angiography. The groups were comparable with respect to age, gender, peak exercise level, and double products achieved. Circumflex artery was the infarct-related one in the majority (21/24; 88%) of patients with an index > 1, whereas most (51/58; 88%) patients with an index < 1 had the culprit lesion in their right coronary artery (p<0.001). The ratio of exercise-induced ST elevations in leads L II and L III has a significantly high ability to discriminate the infarct-related coronary artery in patients with uncomplicated inferior myocardial infarction. Considering the prognostic importance of the type of coronary involvement, this index could be a part of predischarge evaluation in this patient group. 相似文献
120.