全文获取类型
收费全文 | 916篇 |
免费 | 47篇 |
国内免费 | 24篇 |
专业分类
耳鼻咽喉 | 1篇 |
儿科学 | 31篇 |
妇产科学 | 19篇 |
基础医学 | 82篇 |
口腔科学 | 44篇 |
临床医学 | 113篇 |
内科学 | 232篇 |
皮肤病学 | 45篇 |
神经病学 | 61篇 |
特种医学 | 105篇 |
外科学 | 38篇 |
综合类 | 73篇 |
预防医学 | 55篇 |
眼科学 | 22篇 |
药学 | 27篇 |
中国医学 | 1篇 |
肿瘤学 | 38篇 |
出版年
2021年 | 6篇 |
2020年 | 6篇 |
2018年 | 5篇 |
2017年 | 7篇 |
2016年 | 14篇 |
2015年 | 12篇 |
2014年 | 19篇 |
2013年 | 59篇 |
2012年 | 15篇 |
2011年 | 26篇 |
2010年 | 36篇 |
2009年 | 38篇 |
2008年 | 17篇 |
2007年 | 40篇 |
2006年 | 18篇 |
2005年 | 19篇 |
2004年 | 18篇 |
2003年 | 19篇 |
2002年 | 16篇 |
2001年 | 15篇 |
2000年 | 15篇 |
1999年 | 20篇 |
1998年 | 50篇 |
1997年 | 48篇 |
1996年 | 36篇 |
1995年 | 27篇 |
1994年 | 31篇 |
1993年 | 35篇 |
1992年 | 7篇 |
1991年 | 11篇 |
1990年 | 17篇 |
1989年 | 37篇 |
1988年 | 21篇 |
1987年 | 23篇 |
1986年 | 16篇 |
1985年 | 7篇 |
1984年 | 9篇 |
1983年 | 7篇 |
1982年 | 9篇 |
1981年 | 10篇 |
1980年 | 10篇 |
1977年 | 5篇 |
1976年 | 7篇 |
1975年 | 6篇 |
1965年 | 4篇 |
1963年 | 6篇 |
1962年 | 5篇 |
1960年 | 5篇 |
1955年 | 4篇 |
1941年 | 11篇 |
排序方式: 共有987条查询结果,搜索用时 15 毫秒
81.
82.
OBJECTIVE: The purpose of this study was to determine the effect of left-to-right shunting on the resting energy expenditure (REE), total energy expenditure (TEE), and energy intake in a group of 3- to 5-month-old infants with moderate to large unrepaired ventricular septal defects (VSDs) compared with age-matched, healthy infants. METHODS: Eight infants with VSDs and 10 healthy controls between 3 to 5 months of age participated in the study. Indirect calorimetry was used to measure REE and the doubly-labeled water method was used to measure TEE and energy intake. An echocardiogram and anthropometric measurements were performed on all study participants. Daily urine samples were collected at home for 7 days. Samples were analyzed by isotope ratio mass spectrometry. Data were compared using analysis of variance. RESULTS: No significant differences were found in REE (VSD, 42.2 +/- 8.7 kcal/kg/d; control, 43.9 +/- 14.1 kcal/kg/d) or energy intake (VSD, 90.8 +/- 19.9 kcal/kg/d; control, 87.1 +/- 11.7 kcal/kg/d) between the groups. The percent total body water was significantly higher in the VSD infants and the percent fat mass was significantly lower. TEE was 40% higher in the VSD group (VSD, 87.6 +/- 10.8 kcal/kg/d; control, 61.9 +/- 10.3 kcal/kg/d). The difference between TEE and REE, reflecting the energy of activity, was 2.5 times greater in the VSD group. CONCLUSIONS: REE and energy intake are virtually identical between the two groups. Despite this, infants with VSDs have substantially higher TEE than age-matched healthy infants. The large difference between TEE and REE in VSD infants suggests a substantially elevated energy cost of physical activity in these infants. These results demonstrate that, although infants with VSDs may match the energy intake of healthy infants, they are unable to meet their increased energy demands, resulting in growth retardation. 相似文献
83.
84.
清开灵与利巴韦林治疗小儿呼吸道合胞病毒肺炎的比较:单盲、随机、平行对照试验 总被引:1,自引:0,他引:1
目的:比较清开灵与利巴韦林对呼吸道合胞病毒肺炎患儿治疗效果的差异。方法:选择2005-02/2006-04在北京儿童医院分中心治疗的小儿呼吸道合胞病毒肺炎97例,患儿法定监护人知情同意。采用单盲、随机、平行对照试验的原则,按区组随机化方法分为2组,清开灵注射液组49例,利巴韦林组48例。①清开灵注射液组:清开灵注射液静脉滴注加口服中成药。②利巴韦林组:利巴韦林注射液静脉滴注加口服复方愈创木酚磺酸钾口服液。两组疗程均为10d,比较两组患儿的疗效。结果:清开灵注射液组脱落3例,利巴韦林组脱落1例,进入结果分析清开灵注射液组46例,利巴韦林组47例。①清开灵注射液组发热患儿体温恢复正常时间比利巴韦林组短[(2.72±1.86)d,(6.29±2.41)d(P<0.01)]。②清开灵注射液组患儿咳嗽、痰壅、气促症状积分改善方面优于利巴韦林组(P<0.05~0.01)。③清开灵注射液组的呼吸道合胞病毒转阴时间明显优于利巴韦林组。④咳嗽、痰壅、病毒转阴时间、气促均进入Logistic模型,其中前两个症状的回归系数绝对值较大。结论:清开灵注射液治疗小儿呼吸道合胞病毒肺炎在退热、止咳平喘、呼吸道合胞病毒转阴时间等方面均具有明显优势,咳嗽、痰壅这两个症状更能反映清开灵注射液的疗效优于利巴韦林。 相似文献
85.
目的:应用蛋白质组技术比较人表皮细胞与角膜上皮细胞之间的蛋白质表达差异。方法:实验于2005-11,2006-10在中山大学中山眼科中心国家眼科学重点实验室完成。分别培养人表皮细胞与角膜上皮细胞,裂解原代细胞抽提总蛋白,精确定量后进行双向电泳,扫描电泳凝胶获得二维总蛋白图谱。图谱使用软件辅助比较分析,找出差异表达点,从凝胶中抠取差异点,胶内酶解后用基质辅助激光解吸附,电离飞行时间串级质谱法鉴定差异蛋白。结果:人表皮细胞与角膜上皮细胞蛋白质凝胶分析获得600余个清晰的蛋白质斑点,在比较分析出的26个差异点中初步鉴定出4个差异表达蛋白,分别是细胞内氯离子通道1、Psodasin、乳酸脱氢酶B和丝氨酸蛋白酶抑制因子。结论:人表皮细胞与角膜上皮细胞在蛋白质表达上有较高的相似性以及较好的可比性,为探索表皮细胞横向分化成角膜上皮细胞的分子机制做出了有益的尝试,并提供了具有一定可操作性的实验方法。 相似文献
86.
87.
Risk of HIV infection attributable to oral sex among men who have sex with men and in the population of men who have sex with men 总被引:4,自引:0,他引:4
Page-Shafer K Shiboski CH Osmond DH Dilley J McFarland W Shiboski SC Klausner JD Balls J Greenspan D Greenspan JS 《AIDS (London, England)》2002,16(17):2350-2352
We examined HIV infection and estimated the population-attributable risk percentage (PAR%) for HIV associated fellatio among men who have sex with other men (MSM). Among 239 MSM who practised exclusively fellatio in the past 6 months, 50% had three partners, 98% unprotected; and 28% had an HIV-positive partner; no HIV was detected. PAR%, based on the number of fellatio partners, ranges from 0.10% for one partner to 0.31% for three partners. The risk of HIV attributable to fellatio is extremely low. 相似文献
88.
Tagny CT Kouao MD Touré H Gargouri J Fazul AS Ouattara S Anani L Othmani H Feteke L Dahourou H Mbensa GO Molé S Nébié Y Mbangue M Toukam M Boulahi MO Andriambelo LV Rakoto O Baby M Yahaya R Bokilo A Senyana F Mbanya D Shiboski C Murphy EL Lefrère JJ 《Transfusion》2012,52(1):134-143
BACKGROUND: The goal of selecting a healthy blood donor is to safeguard donors and reduce the risks of infections and immunologic complications for recipients. STUDY DESIGN AND METHODS: To evaluate the blood donor selection process, a survey was conducted in 28 blood transfusion centers located in 15 francophone African countries. Data collected included availability of blood products, risk factors for infection identified among blood donor candidates, the processing of the information collected before blood collection, the review process for the medical history of blood donor candidates, and deferral criteria for donor candidates. RESULTS: During the year 2009, participating transfusion centers identified 366,924 blood donor candidates. A mean of 13% (range, 0%‐36%) of the donor candidates were excluded based solely on their medical status. The main risk factors for blood‐borne infections were having multiple sex partners, sexual intercourse with occasional partners, and religious scarification. Most transfusion centers collected this information verbally instead of having a written questionnaire. The topics least addressed were the possible complications relating to the donation, religious scarifications, and history of sickle cell anemia and hemorrhage. Only three centers recorded the temperature of the blood donors. The deferral criteria least reported were sickle cell anemia, piercing, scarification, and tattoo. CONCLUSIONS: The medical selection process was not performed systemically and thoroughly enough, given the regional epidemiologic risks. It is essential to identify the risk factors specific to francophone African countries and modify the current medical history questionnaires to develop a more effective and relevant selection process. 相似文献
89.
Cytogenetic and histologic correlations in malignant lymphoma 总被引:9,自引:0,他引:9
Koduru PR; Filippa DA; Richardson ME; Jhanwar SC; Chaganti SR; Koziner B; Clarkson BD; Lieberman PH; Chaganti RS 《Blood》1987,69(1):97-102
Although a number of studies have indicated correlations between histologic subtypes of tumors and certain nonrandom chromosome changes, cytogenetic studies of lymphoma are in an early stage compared to those of leukemia. No comprehensive analysis of available data has so far been attempted in the literature either. Here we present an analysis of chromosome changes and their correlation with subtypes of lymphoma studied by conventional histology and cell surface markers, as observed in two sets of data: a group of 65 karyotypically abnormal tumors sequentially ascertained and studied by us during the period January 1, 1984 to April 30, 1985, and a larger data set derived by combining our data with those from two published series from the University of Minnesota that are comparable to our data. These combined data, which comprise the largest data set on the cytogenetics of lymphomas assembled so far, enabled a comprehensive analysis of correlation between chromosome change and tumor histology and the patterns of chromosome instability in these tumors. We found several significant associations, some previously described and others now recognized, between nonrandom chromosome gains, breaks, translocations, and deletions and histologic subtypes of tumors that characterize lymphomas. The data indicate that finding of chromosome breaks at certain sites (eg, 8q24, 14q32, 18q21) is of diagnostic value in dealing with cases of unusual lymphoma. Furthermore, nonrandom chromosome breakage exhibited three distinct patterns that reflected three levels of etiologically relevant genetic change. 相似文献
90.
Liu SC; Palek J; Yi SJ; Nichols PE; Derick LH; Chiou SS; Amato D; Corbett JD; Cho MR; Golan DE 《Blood》1995,86(1):349-358
Southeast Asian ovalocytosis (SAO) is an asymptomatic trait characterized by rigid, poorly deformable red cells that resist invasion by several strains of malaria parasites. The underlying molecular genetic defect involves simple heterozygous state for a mutant band 3 protein, which contains a deletion of amino acids 400 through 408, linked with a Lys 56-to-Glu substitution (band 3-Memphis polymorphism). To elucidate the contribution of the mutant SAO band 3 protein to increased SAO red blood cell (RBC) rigidity, we examined the participation of the mutant SAO band 3 protein in increased band 3 attachment to the skeleton and band 3 oligomerization. We found first that SAO RBC skeletons retained more band 3 than normal cells and that this increased retention preferentially involved the mutant SAO band 3 protein. Second, SAO RBCs contained a higher percentage of band 3 oligomer-ankyrin complexes than normal cells, and these oligomers were preferentially enriched by the mutant SAO protein. At the ultrastructural level, the increased oligomer formation of SAO RBCs was reflected by stacking of band 3-containing intramembrane particles (IMP) into longitudinal strands. The IMP stacking was not reversed by treating SAO RBCs in alkaline pH (pH 11), which is known to weaken ankyrin-band 3 interactions, or by removing the cytoplasmic domain of band 3 from SAO membranes with trypsin. Finally, we found that band 3 protein in intact SAO RBCs exhibited a markedly decreased rotational mobility, presumably reflecting the increased oligomerization and the membrane skeletal association of the SAO band 3 protein. We propose that the mutant SAO band 3 has an increased propensity to form oligomers, which appear as longitudinal strands of IMP and exhibit increased association with membrane skeleton. This band 3 oligomerization underlies the increase in membrane rigidity by precluding membrane skeletal extension, which is necessary for membrane deformation. 相似文献