全文获取类型
收费全文 | 13764篇 |
免费 | 1030篇 |
国内免费 | 38篇 |
专业分类
耳鼻咽喉 | 183篇 |
儿科学 | 355篇 |
妇产科学 | 363篇 |
基础医学 | 1727篇 |
口腔科学 | 231篇 |
临床医学 | 1476篇 |
内科学 | 2695篇 |
皮肤病学 | 97篇 |
神经病学 | 1244篇 |
特种医学 | 475篇 |
外科学 | 2187篇 |
综合类 | 174篇 |
一般理论 | 13篇 |
预防医学 | 1222篇 |
眼科学 | 846篇 |
药学 | 696篇 |
中国医学 | 9篇 |
肿瘤学 | 839篇 |
出版年
2023年 | 64篇 |
2022年 | 126篇 |
2021年 | 311篇 |
2020年 | 160篇 |
2019年 | 235篇 |
2018年 | 335篇 |
2017年 | 243篇 |
2016年 | 239篇 |
2015年 | 343篇 |
2014年 | 450篇 |
2013年 | 636篇 |
2012年 | 955篇 |
2011年 | 1016篇 |
2010年 | 557篇 |
2009年 | 496篇 |
2008年 | 904篇 |
2007年 | 904篇 |
2006年 | 933篇 |
2005年 | 906篇 |
2004年 | 864篇 |
2003年 | 797篇 |
2002年 | 775篇 |
2001年 | 147篇 |
2000年 | 105篇 |
1999年 | 162篇 |
1998年 | 148篇 |
1997年 | 132篇 |
1996年 | 103篇 |
1995年 | 107篇 |
1994年 | 105篇 |
1993年 | 84篇 |
1992年 | 92篇 |
1991年 | 75篇 |
1990年 | 81篇 |
1989年 | 74篇 |
1988年 | 65篇 |
1987年 | 77篇 |
1986年 | 64篇 |
1985年 | 82篇 |
1984年 | 92篇 |
1983年 | 73篇 |
1982年 | 88篇 |
1981年 | 104篇 |
1980年 | 84篇 |
1979年 | 53篇 |
1978年 | 49篇 |
1977年 | 32篇 |
1976年 | 35篇 |
1975年 | 28篇 |
1974年 | 26篇 |
排序方式: 共有10000条查询结果,搜索用时 312 毫秒
981.
982.
Photodynamic therapy of idiopathic and inflammatory choroidal neovascularization in young adults 总被引:4,自引:0,他引:4
PURPOSE: To evaluate the treatment of subfoveal choroidal neovascularization (CNV) using photodynamic therapy (PDT) with verteporfin (Visudyne; Novartis, Duluth, GA) in young adults. DESIGN: Retrospective noncomparative interventional case series. PARTICIPANTS: Nineteen eyes of 17 patients with classic, subfoveal CNV treated with PDT using verteporfin, excluding eyes with CNV secondary to age-related macular degeneration, angioid streaks, and myopia. MAIN OUTCOME MEASURES: Snellen visual acuity before and after PDT. RESULTS: Nineteen eyes were followed an average of 12.8 months (range, 4-33 months) after PDT. Before treatment, visual acuity measured > or = 20/40 in 0 eyes (0.0%), < 20/40 to > 20/200 in 11 eyes (57.9%), and < or =20/200 in 8 eyes (42.1%). After treatment, visual acuity measured > or =20/40 in four eyes (21.1%), < 20/40 to > 20/200 in eight eyes (42.1%), and < or =20/200 in seven eyes (36.8%). Six eyes (31.6%) underwent retreatment, with only two eyes retreated twice. Four eyes underwent eventual surgical removal of the CNV after PDT. CONCLUSIONS: Photodynamic therapy seems to be useful in stabilizing and improving visual acuity in young adults with subfoveal CNV secondary to idiopathic and inflammatory etiologies. 相似文献
983.
Transient visual and neurological episodes are relatively common and can occur for the first time in middle and old age. In many cases these transient events are migraine auras. An aura is a transient, stereotypical, visual or neurological episode usually lasting 4 to 60 minutes in duration. Migraine is usually, but not always, associated with headache and can be accompanied by systemic and autonomic symptoms. Diagnosis is dependent on International Headache Society criteria. The pathophysiology is believed to involve neurovascular mechanisms. There is a hereditary component to migraine. When migraine auras occur in the absence of headache they are termed acephalgic migraines. Late onset migraine accompaniment is an acephalgic migraine that presents in middle-aged and older adults. It is usually benign. Migraines can be mimicked by other more serious conditions. Most patients with a stable migraine pattern and normal neurological evaluation do not require further testing. Some patients with atypical presentation, older age, or suspected secondary causes need further investigation. 相似文献
984.
Botulinum toxin has been increasingly applied to the treatment of a wide variety of neurological disorders. Its application to headache disorders, and specifically those classified as migraine or tension-type, followed the observation of its effectiveness in decreasing pain. Studies that have primarily used botulinum toxin type A, but with varying dose regimens and sites of administration, have since observed its beneficial effects and in those subjects, headaches have lessened in their frequency or severity. However, questions that have primarily concerned dose and sites of administration have since arisen and clear guidelines for botulinum toxin use in headache disorders have yet to be developed. 相似文献
985.
Optic nerve head drusen 总被引:1,自引:0,他引:1
Optic disc drusen are congenital and developmental anomalies of the optic nerve head seen commonly in clinical practice, often as an incidental ophthalmologic finding during routine exams. Optic disc drusen are a form of calcific degeneration in some of the axons of the optic nerve. Visual acuity is often not affected but the visual fields of these patients can be abnormal and deteriorate over time. Optic disc drusen are familial and are not uncommon. They are thought to be the result of pathology at the level of the optic nerve head itself. The diagnosis can be made with clinical findings combined with B scan ultrasound and computed tomography. In addition, newer modalities using optic nerve head tomography are proving to be very useful. Since children as well as adults are affected, it is important to consider optic nerve head drusen in the differential diagnosis of papilledema or optic nerve swelling. 相似文献
986.
Hollander DA Stewart JM DeAngelis DD Seiff SR 《Ophthalmic plastic and reconstructive surgery》2003,19(3):253-4; author reply 254
987.
PURPOSE: To estimate the potential for surface reflections in recently introduced intraocular lenses (IOLs) and to determine optic surface designs that will reduce surface reflections. SETTING: Mayo Clinic, Rochester, Minnesota, USA. METHODS: Surface-reflected glare in the unaccommodated human crystalline lens and in 6 IOLs (Bausch & Lomb SoFlex LI61U, Pharmacia CeeOn 911A, Allergan Sensar AR40, Bausch & Lomb Hydroview H60M, Alcon AcrySof MA60BM, Alcon AcrySof SA30AL) was examined in a physiologic eye model using the ZEMAX optical design program. Internal and external surface reflections were described and compared in terms of IOL surface reflectivity (%), area of the reflected glare image (mm(2)), and relative intensity of the reflected glare image. RESULTS: Compared to surface reflections from the unaccommodated human lens with a corneal power of 43.0 diopters, all the IOLs increased the relative intensity of internal and external reflections by 3- to 36-fold except the MA60BM and the SA30AL, which increased the relative intensity of internal and external reflections by 730- to 1090-fold. CONCLUSIONS: All the IOLs studied variably increased internal and external surface reflections when compared to the human crystalline lens. Surface reflections were minimized in optic designs with an anterior radius of curvature of approximately 17.0 mm or less. 相似文献
988.
PURPOSE: To identify risk factors in a series of patients who developed steep central islands after laser in situ keratomileusis (LASIK). METHODS: We analyzed and compared the refractive and topographic outcome of a study group composed of 83 eyes of 44 patients who underwent LASIK using the VISX Star3 excimer laser with a refraction-matched control group of 83 eyes treated later. The vacuum aspirator of the excimer laser was abnormally positioned during the surgeries performed in the study group. RESULTS: Mean preoperative spherical equivalent refraction in the study group was -6.75 +/- 2.50 D. Four eyes with a mean preoperative spherical equivalent refraction of -9.27 +/- 2.29 D developed steep central islands. Thirty-three (38%) of 83 eyes treated needed retreatment for residual myopia or myopic astigmatism. In the control group, mean preoperative spherical equivalent refraction was -6.76 +/- 2.50 D. Ninety-three percent of eyes were within +/- 1.00 D of target refraction. Five (6.02%) of 83 eyes required retreatment and no eyes developed central islands. CONCLUSION: The abnormally positioned vacuum aspirator coupled with the higher preoperative refractive correction were the likely causative factors for central island formation and the increased incidence of undercorrection in these patients. 相似文献
989.
The potential for passive cocaine exposure was evaluated in crime laboratory employees preparing training aids for a military working dog program (MWD). The primary goal of the study was to elucidate the routes of exposure and implement procedural changes that would minimize this risk. Several work environments and laboratory procedures were examined by monitoring personal breathing zones (PBZ), ambient airborne cocaine levels in the laboratory spaces, and urinary levels of the primary cocaine metabolite, benzoylecgonine. The study was performed initially using current laboratory procedures to establish a baseline and to identify potential sources of exposure. A subsequent study was performed to determine the effectiveness of the follow-up procedure in reducing exposure. As a result of the changes, the 8-h time weighted averages (TWAs) were 40 to 80% lower in the follow-up study as compared to the baseline assessment. Dermal absorption and PBZ inhalation of cocaine during manufacture were likely the most significant source of cocaine exposure. Ambient airborne cocaine may have also contributed to the total exposure, but for most observations, the concentrations were significantly less than those determined from PBZ monitoring. The maximum ambient cocaine concentration was 0.0144 mg/m(3) compared to a maximum of 0.4004 mg/m(3) observed during PBZ monitoring. Occupational exposure decreased in the follow-up study because of the proper use of personal protective equipment and improvements in engineering controls. 相似文献
990.
Coronary Artery Disease (CAD) remains globally the leading cause of death and long-term morbidity. Among the many manifestations of CAD, acute coronary syndrome (ACS), ranging from unstable angina to acute myocardial infarction, is the most catastrophic event due to our inability to predict its occurrence. Despite improved treatments of CAD, ACS results in sudden death or permanent disability in a substantial percentage of patients. If we could predict the timing of ACS or better yet prevent its occurrence, we could alter the otherwise unfavorable course of CAD. Several studies have convincingly demonstrated that majority of all ACS develops from previously mild to moderate stenoses. Thus, based on these and autopsy studies, sudden disruption or rupture of the non-obstructive "vulnerable" atherosclerotic lesion is currently considered the cause of ACS. Recent clinical studies have substantiated earlier autopsy observations that plaque vulnerability is a systemic process, involving multiple locations concurrently. Although the exact inciting factors of the vulnerable plaque rupture are unknown, inflammation is accepted to be a pivotal event. The possibility of stabilizing the vulnerable plaques has strongly been supported by the lipid lowering trials, in which dramatic reduction of the acute coronary events was noted despite subtle improvements in luminal diameter. Furthermore, antiplatelet therapies have become an important preventative therapy due to the essential role of platelets in the aftermath of plaque rupture. Finally, various imaging modalities to diagnose the plaque vulnerability could help prevent the acute coronary events in the future. 相似文献