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   2500篇
  免费   189篇
  国内免费   59篇
耳鼻咽喉   25篇
儿科学   110篇
妇产科学   45篇
基础医学   342篇
口腔科学   273篇
临床医学   261篇
内科学   515篇
皮肤病学   49篇
神经病学   151篇
特种医学   186篇
外科学   181篇
综合类   26篇
预防医学   243篇
眼科学   27篇
药学   182篇
  1篇
中国医学   34篇
肿瘤学   97篇
  2023年   19篇
  2022年   40篇
  2021年   64篇
  2020年   49篇
  2019年   66篇
  2018年   73篇
  2017年   61篇
  2016年   75篇
  2015年   86篇
  2014年   113篇
  2013年   118篇
  2012年   143篇
  2011年   163篇
  2010年   106篇
  2009年   125篇
  2008年   107篇
  2007年   127篇
  2006年   101篇
  2005年   79篇
  2004年   68篇
  2003年   72篇
  2002年   55篇
  2001年   48篇
  2000年   34篇
  1999年   46篇
  1998年   84篇
  1997年   93篇
  1996年   61篇
  1995年   59篇
  1994年   41篇
  1993年   48篇
  1992年   20篇
  1991年   22篇
  1990年   21篇
  1989年   34篇
  1988年   29篇
  1987年   34篇
  1986年   18篇
  1985年   20篇
  1984年   14篇
  1983年   16篇
  1982年   11篇
  1981年   8篇
  1980年   10篇
  1979年   7篇
  1978年   6篇
  1977年   14篇
  1976年   8篇
  1975年   6篇
  1968年   3篇
排序方式: 共有2748条查询结果,搜索用时 0 毫秒
41.
A literature search, supplemented by an expert survey and selected reanalyses of existing data from epidemiological studies was performed to determine the prevalence and associated burden of bipolar I and II disorder in EU countries. Only studies using established diagnostic instruments based on DSM-III-R or DSM-IV, or ICD-10 criteria were considered. Fourteen studies from a total of 10 countries were identified. The majority of studies reported 12-month estimates of approximately 1% (range 0.5-1.1%), with little evidence of a gender difference. The cumulative lifetime incidence (two prospective-longitudinal studies) is slightly higher (1.5-2%); and when the wider range of bipolar spectrum disorders is considered estimates increased to approximately 6%. Few studies have reported separate estimates for bipolar I and II disorders. Age of first onset of bipolar disorder is most frequently reported in late adolescence and early adulthood. A high degree of concurrent and sequential comorbidity with other mental disorders and physical illnesses is common. Most studies suggest equally high or even higher levels of impairments and disabilities of bipolar disorders as compared to major depression and schizophrenia. Few data are available on treatment and health care utilization.  相似文献   
42.
43.
Four new prenylated isoflavonoids, vogelins D-G (1-4), were isolated from the CH2Cl2 extract of Erythrina vogelii root bark in addition to the known compounds isolupalbigenin (5), ficuisoflavone (6), ulexone (7), isochandalon (8), and isoderrone (9). The structures 1-4 were elucidated by spectroscopic and chemical methods. The absolute configuration of compound 1 was determined on the basis of its CD spectrum. Possible biogenetic relationships among the E. vogelii isoflavonoids are briefly discussed.  相似文献   
44.
氯地滴眼液的含量测定   总被引:4,自引:0,他引:4  
目的:采用HPLC法测定氯地滴眼液中氯霉素和地塞米松磷酸钠的含量。方法:色谱分析条件:ODS柱作分析柱,流动相为甲醇/水体系,0 ̄8min使用40%甲醇,8 ̄16min使用60%甲醇,流速1ml/min,0 ̄9min240nm紫外检测,:二组分分离良好。各组各组性关系良好,平均回收率氯霉素99.8%(RSD=1.2%,n=5),地塞米松磷酸钠99.4%(RSD=0.7%,n=5),结论:该法用于氯  相似文献   
45.
46.
47.
Objectives To estimate, by neonatal screening, the birth prevalence of congenital toxoplasmosis among live‐born infants in Sergipe state, Brazil, and to investigate the clinical features of affected infants. Methods Dried blood spot specimens obtained from 15 204 neonates were assayed for the presence of anti‐T. gondii IgM antibodies. Duplicate retesting was done in infants with positive and borderline results. Confirmatory testing in peripheral blood samples consisted of testing for anti‐T. gondii IgG and IgM in infants and mothers. Those with possible congenital toxoplasmosis were evaluated and followed up to a median age of 20 months. Congenital infection was confirmed in the presence of persisting anti‐T. gondii IgG antibodies beyond 12 months of age. All infants with confirmed infection were treated with pyrimethamine, sulfadiazine and folinic acid for 1 year. Results Fifty‐three infants had detectable IgM in dried blood spot specimens. Confirmatory testing was reactive in 39/50, of which, 38 completed follow‐up. Six of 15 204 newborns were diagnosed with congenital toxoplasmosis, resulting in an estimated birth prevalence of four per 10 000 [CI 95% 1.4–8.0]. Four infants (67%) showed signs of congenital toxoplasmosis in their first year of life; three (75%) had retinochoroidal scars, and one had cerebral calcifications. Two infants remained asymptomatic until 20 months of age. Conclusions The birth prevalence of congenital toxoplasmosis is high in the Brazilian state of Sergipe, with most of the infants showing ocular lesions. Preventive measures are strongly warranted.  相似文献   
48.
Context: Buchenavia tetraphylla (Aubl.) RA Howard (Combretaceae: Combretoideae) is an ethnomedicinal plant with reported antifungal action.

Objective: This study evaluates the antimicrobial activity of B. tetraphylla leaf extracts against clinical isolates of Candida albicans. The morphological alterations, combinatory effects with fluconazole and the cytotoxicity of the active extract were analyzed.

Materials and methods: Extracts were obtained using different solvents (hexane: BTHE; chloroform: BTCE; ethyl acetate: BTEE; and methanol: BTME). Antimicrobial activity was determined by the broth microdilution method using nine strains of C. albicans isolated from vaginal secretions and one standard strain (UFPEDA 1007).

Results: All extracts showed anti-C. albicans activity, including against the azole-resistant strains. The MIC values ranged from 156 to 2500?μg/mL for the BTHE; 156 to 1250?μg/mL for the BTCE; 625 to 1250?μg/mL for the BTME and 625?μg/mL to 2500?μg/mL for the BTEE. BTME showed the best anti-C. albicans activity. This extract demonstrated additive/synergistic interactions with fluconazole. Scanning electron microscopy analysis suggested that the BTME interferes with the cell division and development of C. albicans. BTME showed IC50 values of 981 and 3935?μg/mL, against J774 macrophages and human erythrocytes, respectively. This extract also enhanced the production of nitric oxide by J774 macrophages.

Discussion and conclusion: Buchenavia tetraphylla methanolic extract (BTME) is a great source of antimicrobial compounds that are able to enhance the action of fluconazole against different C. albicans strains; this action seems related to inhibition of cell division.  相似文献   
49.
50.
A 35-year-old African Brazilian patient had sickle cell anemia complicated with recurrent vasoocclusive (VOC) crises and refractory painful leg ulcers for 16 years. The ulcers started over both medial malleoli and expanded gradually. The ulcer on the left leg spread from the foot to the knee circumferentially and was refractory to all forms of therapy within the frame work of multi-disciplinary care. The patient agreed to a below the knee amputation of the left leg. He felt much better after the amputation but developed severe neuropathic phantom pain that was well controlled medically. He could differentiate the sickle cell anemia and ulcer pain from the neuropathic pain. About 6 months after the amputation he had dengue fever with fatal outcome. This is the first report of treatment of refractory sickle cell anemia leg ulcer with amputation and probably the first report of a Brazilian patient with sickle cell anemia and dengue fever.  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