全文获取类型
收费全文 | 1385篇 |
免费 | 80篇 |
国内免费 | 1篇 |
学科分类
医药卫生 | 1466篇 |
出版年
2023年 | 9篇 |
2022年 | 26篇 |
2021年 | 34篇 |
2020年 | 20篇 |
2019年 | 23篇 |
2018年 | 40篇 |
2017年 | 31篇 |
2016年 | 29篇 |
2015年 | 45篇 |
2014年 | 51篇 |
2013年 | 63篇 |
2012年 | 83篇 |
2011年 | 107篇 |
2010年 | 47篇 |
2009年 | 37篇 |
2008年 | 86篇 |
2007年 | 101篇 |
2006年 | 84篇 |
2005年 | 74篇 |
2004年 | 98篇 |
2003年 | 75篇 |
2002年 | 78篇 |
2001年 | 19篇 |
2000年 | 11篇 |
1999年 | 8篇 |
1998年 | 15篇 |
1997年 | 11篇 |
1996年 | 9篇 |
1995年 | 8篇 |
1994年 | 6篇 |
1993年 | 7篇 |
1992年 | 7篇 |
1990年 | 4篇 |
1989年 | 3篇 |
1988年 | 3篇 |
1987年 | 6篇 |
1986年 | 4篇 |
1984年 | 6篇 |
1983年 | 6篇 |
1982年 | 8篇 |
1981年 | 3篇 |
1980年 | 3篇 |
1979年 | 3篇 |
1974年 | 3篇 |
1973年 | 3篇 |
1972年 | 3篇 |
1963年 | 3篇 |
1941年 | 4篇 |
1940年 | 3篇 |
1927年 | 5篇 |
排序方式: 共有1466条查询结果,搜索用时 31 毫秒
71.
72.
This study compared nutritional intake during pregnancy among women of Mexican descent according to country of birth (US vs. Mexico) and, for Mexico-born women, according to number of years lived in the US (or= 11 years). A 72-item food frequency questionnaire (FFQ) was used to assess dietary intake in 474 pregnant Mexico-born immigrants and US-born Mexican-Americans. Mexico-born women had significantly higher intakes of calories (P = 0.02), fibre (P < 0.001), vitamin A (P < 0.001), vitamin C (P = 0.03), vitamin E (P < 0.01), folate (P < 0.01), calcium (P < 0.001) and zinc (P = 0.02) from their diets than US-born women. Intakes of all nutrients except vitamin C and zinc remained significantly higher in Mexico-born women when nutrients from both diet and vitamin supplements were considered. Among Mexico-born women, increasing years of residence in the US was associated with lower intake of calories (P(trend) < 0.01), fibre (P(trend) < 0.01), folate (P(trend) = 0.03), iron (P(trend) = 0.05) and zinc (P(trend) = 0.03), although only the trend for iron remained significant when vitamin supplement sources were included. A large percentage of women had inadequate intake of vitamin E (58%), folate (61%), iron (77%) and zinc (47%) from their diets during pregnancy and these rates were higher in US-born women than Mexico-born women. 相似文献
73.
Fantini SM Paiva JB Rino Neto J Dominguez GC Abrão J Vigoritto JW 《Brazilian Oral Research》2005,19(3):176-182
The present study assessed condylar displacement between initial maximal habitual intercuspation (MHI) and centric relation (CR), recorded after using a deprogramming occlusal splint for an average period of 7.8 +/- 2.1 months prior to any orthodontic treatment. The sample consisted of 22 subjects, 11 male and 11 female, with an average age of 14.2 +/- 1.4 years, with Class II malocclusion and with no apparent signs or symptoms of temporomandibular dysfunction (TMD). Condylar displacement was measured using a Panadent axis position indicator in decimal fractions of a millimeter. The original mean vertical displacements and the corresponding standard deviations were 4.24 +/- 2.53 mm and 3.86 +/- 2.72 mm, respectively, for the right and left sides. Because a significant negative correlation was observed between original condylar displacements and age factors, the displacement values were statistically adjusted to 2.74 +/- 2.00 mm and 2.44 +/- 1.93 mm. On the horizontal plane, the mean displacements measured were -0.72 +/- 1.53 mm on the right side and -0.51 +/- 1.98 mm on the left. The mean displacement on the transversal plane was 0.03 +/- 0.87 mm. A comparison between these values and those observed in non-deprogrammed groups, as well as those published in the related literature, indicates that use of occlusal splints results in greater mean condylar displacement values, especially vertically, between CR and MHI positions, which contributed to a more accurate orthodontic diagnosis. 相似文献
74.
75.
Baxley Gladys B.; Turner Paul F.; Greenwold Warren E. 《Journal of pediatric psychology》1978,3(4):172-176
Twenty-six hyperactive males, with a mean age of 11 years, 7months who were receiving stimulant medication were individuallyinterviewed to assess their knowledge, attitudes, and perceptionsof the consequences of their drug treatment. Subjects' audiotapedresponses to the interview questions were content-analyzed andcategorized according to the percent of subjects who gave thesame (or similar) responses to each question. The responsesshowed that the subjects were generally knowledgeable aboutthe purpose of their medication, presented generally mixed attitudesabout having to take medication, but tended to associate nottaking the medication with certain negative consequences. Thesefindings may have some clinical relevance for the outcome ofdrug treatment of hyperactive children. 相似文献
76.
77.
Onambele GN Bruce SA Woledge RC 《Pflügers Archiv : European journal of physiology》2004,448(4):457-461
We have observed the force resulting from sudden stretches (3–10 mm in 10–20 ms) of human adductor pollicis muscle during voluntary contractions maintaining different proportions of the maximum voluntary force from 20% to 100%. The ratio of the peak force during stretch (S) to the voluntary force (I) just before the start of the stretch was calculated. The S/I ratio was dependent both on the level of activation and the speed of the stretch. At all levels of activation S/I increased exponentially with velocity towards a plateau value with an exponential constant of about 150 mm/s. The plateau values reached were dependent on activation level (P<0.02, linear regression, n=24). At 96% activation the plateau value of the S/I ratio was 1.82±0.13 (mean±95% confidence limits); at 32% activation the value was 2.72±0.23. 相似文献
78.
Bayard V Kitsutani PT Barria EO Ruedas LA Tinnin DS Muñoz C de Mosca IB Guerrero G Kant R Garcia A Caceres L Gracio FG Quiroz E de Castillo Z Armien B Libel M Mills JN Khan AS Nichol ST Rollin PE Ksiazek TG Peters CJ 《Emerging infectious diseases》2004,10(9):1635-1642
An outbreak of hantavirus pulmonary syndrome occurred in the province of Los Santos, Panama, in late 1999 and early 2000. Eleven cases were identified; 9 were confirmed by serology. Three cases were fatal; however, no confirmed case-patient died. Case-neighborhood serologic surveys resulted in an overall hantavirus antibody prevalence of 13% among household and neighborhood members from the outbreak foci. Epidemiologic investigations did not suggest person-to-person transmission of hantavirus infection. By use of Sin Nombre virus antigen, hantavirus antibodies were detected in Oligoryzomys fulvescens and Zygodontomys brevicauda cherriei. This outbreak resulted in the first documented cases of human hantavirus infections in Central America. 相似文献
79.
Follicular fluid antibodies to Chlamydia trachomatis and human heat shock protein-60 kDa and infertility in women 总被引:4,自引:0,他引:4
BACKGROUND: The objective of this study was to establish the relationship between presence of anti-Chlamydia trachomatis and anti-HSP60 antibodies in serum and follicular fluid of infertile women. METHODS: Serum IgG and follicular fluid IgA to Chlamydia trachomatis and human heat shock protein 60 (HSP60) were determined in 41 women undergoing in vitro fertilization (IVF). RESULTS: A significant association was found between presence of bacterial antibodies in serum and IgA anti-HSP60 in follicular fluid. CONCLUSIONS: Chlamydia trachomatis infection might be triggering an autoimmune process that could negatively affect the success of IVF. 相似文献
80.
Atanasova B Mudway IS Laftah AH Latunde-Dada GO McKie AT Peters TJ Tzatchev KN Simpson RJ 《The Journal of nutrition》2004,134(3):501-505
Ascorbate has long been thought to play an important role in intestinal iron absorption. The recent identification of a possible ascorbate-dependent duodenal ferric reductase suggests a role for intracellular ascorbate in the control of iron absorption. We set out to determine whether duodenal ascorbate concentrations are altered by treatments known to alter the rate of iron absorption and whether ascorbate levels affect duodenal reductase activity. Duodenal ascorbate was extracted and assayed by HPLC and/or a chemical assay. Ferric reductase was assayed in vitro with ferric nitrilotriacetate or nitroblue tetrazolium as substrates. Duodenal ascorbate concentrations were increased by iron deficiency, genetic hypotransferrinemia, and hypoxia. Parenteral iron overload increased iron stores but did not affect duodenal ascorbate concentrations. Hemolytic anemia induced in mice by phenylhydrazine injection also did not affect duodenal ascorbate concentrations. In vitro studies with incubated duodenum showed that decreased tissue ascorbate was associated with decreased mucosal ferric reductase activity, whereas incubation with dehydroascorbate prevented both the decrease in ascorbate concentration and reductase activity. Mouse duodenum ascorbate concentrations changed in response to treatments that altered iron absorption rates; in particular, ascorbate levels generally increased when iron absorption was increased by iron deficiency, hypoxia, or genetic hypotransferrinemia. We conclude that changes in ascorbate levels are associated with changes in ferric reductase activity. These findings are consistent with the proposal that duodenal ascorbate plays a role in intestinal iron absorption. 相似文献