全文获取类型
收费全文 | 853篇 |
免费 | 38篇 |
国内免费 | 9篇 |
专业分类
耳鼻咽喉 | 36篇 |
儿科学 | 31篇 |
妇产科学 | 46篇 |
基础医学 | 50篇 |
口腔科学 | 31篇 |
临床医学 | 62篇 |
内科学 | 133篇 |
皮肤病学 | 14篇 |
神经病学 | 53篇 |
特种医学 | 47篇 |
外科学 | 119篇 |
综合类 | 14篇 |
一般理论 | 2篇 |
预防医学 | 16篇 |
眼科学 | 144篇 |
药学 | 50篇 |
中国医学 | 8篇 |
肿瘤学 | 44篇 |
出版年
2023年 | 6篇 |
2022年 | 15篇 |
2021年 | 18篇 |
2020年 | 14篇 |
2019年 | 29篇 |
2018年 | 23篇 |
2017年 | 20篇 |
2016年 | 42篇 |
2015年 | 35篇 |
2014年 | 40篇 |
2013年 | 53篇 |
2012年 | 51篇 |
2011年 | 55篇 |
2010年 | 34篇 |
2009年 | 16篇 |
2008年 | 49篇 |
2007年 | 59篇 |
2006年 | 45篇 |
2005年 | 54篇 |
2004年 | 41篇 |
2003年 | 44篇 |
2002年 | 46篇 |
2001年 | 33篇 |
2000年 | 22篇 |
1999年 | 19篇 |
1998年 | 5篇 |
1997年 | 5篇 |
1996年 | 4篇 |
1995年 | 4篇 |
1994年 | 2篇 |
1992年 | 2篇 |
1991年 | 4篇 |
1990年 | 3篇 |
1989年 | 3篇 |
1986年 | 3篇 |
1985年 | 1篇 |
1983年 | 1篇 |
排序方式: 共有900条查询结果,搜索用时 0 毫秒
41.
Vitrectomy in eyes with unsuspected retinoblastoma 总被引:3,自引:0,他引:3
OBJECTIVE: To analyze patient management and prognosis after vitrectomy in eyes with unsuspected retinoblastoma. DESIGN: Retrospective, noncomparative case series. PARTICIPANTS: Eleven consecutive patients who had undergone vitrectomy on an eye with unsuspected retinoblastoma. MAIN OUTCOME MEASURES: The two main outcome measures were ultimate patient management and the development of retinoblastoma metastasis. RESULTS: Of more than 900 consecutive patients with retinoblastoma managed on the Ocular Oncology Service at Wills Eye Hospital in Philadelphia, 11 (1%) had prior vitrectomy in an eye with viable tumor before referral to us for suspected retinoblastoma. The main preoperative diagnoses included vitreous hemorrhage in seven patients (64%), toxocariasis in two patients (18%), toxoplasmosis in one patient (9%), and endophthalmitis in one patient (9%). In no case was retinoblastoma suspected before vitrectomy. The mean patient age at vitrectomy was 6 years. Retinoblastoma was later suspected during vitrectomy in two patients (18%), on cytologic examination of the vitrectomy specimen in eight patients (73%), and after referral in one patient (9%). The mean interval between vitrectomy and referral to us was 23 days. On examination, the globe was classified as Reese-Ellsworth group Vb in all 11 patients (100%). Anterior chamber tumor cells were clinically visible in four eyes (36%), hyphema in two eyes (18%), and iris neovascularization in two eyes (18%). Retinoblastoma cells were visualized in the vitreous in seven eyes (64%) and not visualized in four eyes (36%) that had vitreous blood. Enucleation was necessary in all 11 patients (100%). Adjuvant treatment was delivered in 10 patients (91%), using orbital radiotherapy in nine patients (82%) and chemotherapy in nine patients (82%). Histopathologic evidence of retinoblastoma invasion was documented in the episclera (two eyes; 18%), anterior chamber (seven eyes; 64%), iris (five eyes; 45%), ciliary body (five eyes; 45%), choroid (three eyes; 27%), and optic nerve (four eyes; 36%; prelaminar, two eyes; postlaminar, two eyes). The vitrectomy ports, Tenon's fascia, cut end of the optic nerve, and orbit were free of tumor. Of the 10 patients who received prophylactic chemotherapy, radiotherapy, or both in addition to enucleation for prevention of retinoblastoma metastasis, none (0%) experienced metastasis or orbital recurrence during the mean follow-up of 7 years (range, 0.2-24 years) from the time of retinoblastoma diagnosis. However, one patient was referred to us after the development of metastatic retinoblastoma, and despite aggressive chemotherapy and radiotherapy after enucleation, died 24 months later. CONCLUSIONS: Retinoblastoma may present with atypical features such as vitreous hemorrhage or signs of vitreous inflammation, particularly in older children. Vitrectomy should be avoided in these cases until the possibility of underlying retinoblastoma is excluded. If vitrectomy is performed in an eye with unsuspected retinoblastoma, enucleation combined with adjuvant chemotherapy, radiotherapy, or both without delay is advised to prevent systemic tumor dissemination. 相似文献
42.
Singh AD Demirci H Shields CL Shields JA Smith AF 《American journal of ophthalmology》2000,130(5):679-680
PURPOSE: To report the concurrent occurrence of choroidal melanoma in a son and father. METHODS: Case reports. The likelihood of familial occurrence of uveal melanoma in which father and son are affected was estimated using the principles of probability. RESULTS: Unilateral choroidal melanoma was diagnosed in a 41-year-old man. Three months later, his 68-year-old father presented with a pigmented choroidal mass that greatly increased in size during the next 6 months and was diagnosed a choroidal melanoma. No personal or family history of atypical moles, cutaneous melanoma, or other malignancy existed. The likelihood of familial occurrence of uveal melanoma using principles of probability was estimated to be 1 in 10 million. CONCLUSION: Considering the low prevalence of uveal melanoma in the general population, the likelihood of uveal melanoma occurring in a family setting is remote. 相似文献
43.
44.
45.
46.
Demirci H Shields CL Shields JA Honavar SG Eagle RC 《Retina (Philadelphia, Pa.)》2002,22(6):698-706; quiz 852-3
BACKGROUND: Ring melanoma of the ciliary body is a rare variant of uveal melanoma that has a poor prognosis. Only isolated cases have been reported in the literature. METHODS: A retrospective review of the clinical features, management, histopathology, and prognosis of 23 consecutive patients with ring melanoma of the ciliary body was performed. RESULTS: Of 8,800 patients with uveal melanoma treated on the Oncology Service at Wills Eye Hospital over a 25-year period, only 23 patients (0.3%) were found to have ring melanoma of the ciliary body. The mean patient age was 59 years (median, 63 years; range, 8-81 years). The only visual symptom was blurred vision in 17 patients (74%), and the other six patients (26%) were asymptomatic. At the initial presentation elsewhere, melanoma was recognized in 13 cases (57%). In the remaining 10 cases (43%), the initial clinical diagnosis was glaucoma in three (13%), iris nevus in three (13%), cataract in two (9%), ciliary body detachment in one (4%), and iridocyclitis in one (4%). The patients were observed elsewhere for a mean of 3 months before the diagnosis of melanoma was suspected and referral to Oncology Service was made. On examination, the tumor involved a mean of eight clock hours of the ciliary body. Seven patients (30%) had complete circumferential (360 degrees) involvement of the ciliary body, and 16 (70%) had incomplete (180-360 degrees) ring involvement. The mean tumor thickness was 8 mm. Associated findings included neovascularization of the iris in one case (4%), shallow anterior chamber in 11 (48%), anterior chamber inflammation in five (22%), cataract in nine (39%), lens indentation in eight (35%), and lens subluxation in three (13%). A prominent episcleral (sentinel) vessel (17 cases, 74%), multilobulation of the mass (19 cases, 83%), blockage of light on transillumination (23 cases, 100%), and ultrasonographic hollowness with intrinsic pulsations (23 cases, 100%) were important features differentiating this tumor from simulating conditions. The tumor was managed with enucleation in all 23 patients. Histopathologic studies revealed epithelioid cell-type melanoma in two patients (9%), mixed cell-type in 17 (74%), and spindle cell-type in four (17%). Extraocular extension was present in eight patients (35%). Metastasis developed in 12 of 23 patients (52%) after a mean follow-up of 55 months. CONCLUSIONS: Ring melanoma of the ciliary body is a rare tumor that can remain hidden from ophthalmoscopic examination. Certain features, such as prominent episcleral sentinel vessels, multilobulation of the mass, light blockage on transillumination, and ultrasonographic hollowness with intrinsic vascular pulsations, suggest the diagnosis. The life prognosis is poor. 相似文献
47.
PURPOSE: To report a clinicopathologic correlation of an unusual benign lymphocytic iris mass in a patient who had no systemic lymphoproliferative disease. METHODS: Case report. RESULTS: A 49-year-old man developed a circumscribed, tan lesion in his left iris. The lesion was suspected clinically to be an atypical iris melanoma. Histopathologic studies of the resected mass revealed a solid tumor that was comprised of lymphocytes and histiocytes. Immunohistochemical studies identified that most of the cells were T lymphocytes. The histopathologic diagnosis was atypical lymphoid infiltrate. Workup for systemic lymphoma and Epstein-Barr virus infection was negative. CONCLUSION: Lymphoid infiltrate can manifest as a solitary mass that can simulate an iris melanoma. 相似文献
48.
Methidathion (MD) [ O, O-dimethyl S-(2,3-dihydro-5-methoxy-2-oxo-1,3,4-thiadiazol-3-ylmethyl) phosphorodithioate] is one of the most widely used organophosphate insecticides (OPIs) in agriculture and public health programmes. We have, therefore, examined the in vivo and in vitro effects of MD on the serum activities of cholinesterase (ChE), enzymes concerning liver damage and lipid peroxidation (LPO; only in vivo), and have evaluated the ameliorating effects of a combination of vitamins E and C against MD toxicity. The in vivo experimental groups were: control group, MD-treated group (MD), and a group treated with MD plus vitamin E plus vitamin C (MD+Vit). The MD and MD+Vit groups were treated orally with a single dose of 8 mg MD/kg body weight at 0 h. Vitamin E and vitamin C were injected at doses of 150 mg/kg body weight i.m. and 200 mg/kg body weight i.p., respectively, 30 min after the treatment with MD in the MD+Vit group. Blood samples were taken 24 h after the MD administration. For in vitro study, venous blood samples were obtained from volunteers, and serum recovered. The activities of serum enzymes were determined in each sample and these served as 0 h values. Each sample was divided into four portions, each of which served as one of the experimental groups, as follows: control group, vitamin E plus vitamin C group (Vit), MD-treated group (MD) and MD plus vitamin E plus vitamin C group (MD+Vit). Vitamin E and vitamin C were added at doses of 7.5 and 10 micro g/ml, respectively, into the Vit and MD+Vit groups. MD was added at doses of 0.4 mg/ml into the MD and MD+Vit groups. The activities of serum enzymes were determined in each sample at 24 h. The results of the in vivo experiment demonstrated that thiobarbituric acid reactive substances were increased in the MD group compared with the control group, and decreased in the MD+Vit group compared with MD group. ChE activity was decreased in both MD and MD+Vit groups compared with controls and increased in the MD+Vit group compared with the MD group. The activities of aspartate aminotransferase (AST), alkaline phosphatase (ALP), gamma-glutamyltransferase (GGT) and lactate dehydrogenase (LDH) were increased in both the MD and MD+Vit groups compared with the control group. AST activity was decreased in MD+Vit group compared with the MD group. Alanine aminotransferase (ALT) activity was decreased in both the MD and MD+Vit groups compared with control group. The results of in vitro experiment showed that all enzyme activities remained unchanged in both the control and Vit groups compared with values at 0 h. The activities of ChE, ALT and LDH were decreased in both the MD and MD+Vit groups compared with 0 h values. There was no significant difference between the MD and MD+Vit groups. The activities of AST, ALP and GGT remained unchanged in all groups. From these results, it can be concluded that MD caused liver damage, and LPO may be one of the molecular mechanisms involved in MD-induced toxicity. Single-dose treatment with a combination of vitamins E and C after the administration of MD can reduce LPO caused by MD. 相似文献
49.
Chronic urticaria is an important diagnostic and therapeutic problem. We aimed to investigate the sero-prevalence of tissue parasites causing toxocariasis and fasciolosis in patients with chronic urticaria. All cases were analyzed for antibodies against Toxocara canis and Fasciola hepatica by modified (homemade) ELISA. The excretory/secretory products of Toxocara and Fasciola were used as antigens (ES-ELISA) in the test. In this study, the highest toxocariasis seropositivity (29.0%) rate and the highest fasciolosis seropositivity (14.5%) rate were found in patients with chronic urticaria. Fasciolosis seropositivity and total seropositivity of toxocariasis and fasciolosis in patients with chronic urticaria was significantly higher than in healthy controls (p<0.05). Toxocariasis seropositivity in patients with chronic urticaria was not significantly higher than that in healthy controls (p>0.05). We suggest that parasitic infections should be considered as an important cause of chronic urticaria. Serological methods should be used to expose the diagnosis of tissue parasites in such cases. 相似文献
50.
Four new caryophyllene derivatives-14-hydroxy-4, 5-dihydro-beta-caryophyllene (1), 14-acetoxy-4, 5-dihydro-beta-caryophyllene (2), 4, 5-dihydro-beta-caryophyllene-14-al (3), and caryophylla-8(14)-en-5-one (4)-are reported from the essential oil of Betula litwinowii. Compounds 1-4 were characterized by MS and 1D and 2D NMR analyses and chemical transformations. The antibacterial and antifungal activity of 1 is also reported. 相似文献