全文获取类型
收费全文 | 13467篇 |
免费 | 1199篇 |
国内免费 | 40篇 |
专业分类
耳鼻咽喉 | 208篇 |
儿科学 | 437篇 |
妇产科学 | 274篇 |
基础医学 | 2040篇 |
口腔科学 | 313篇 |
临床医学 | 1108篇 |
内科学 | 2745篇 |
皮肤病学 | 178篇 |
神经病学 | 1479篇 |
特种医学 | 453篇 |
外科学 | 2136篇 |
综合类 | 288篇 |
一般理论 | 12篇 |
预防医学 | 1132篇 |
眼科学 | 316篇 |
药学 | 886篇 |
中国医学 | 9篇 |
肿瘤学 | 692篇 |
出版年
2021年 | 171篇 |
2020年 | 99篇 |
2019年 | 182篇 |
2018年 | 196篇 |
2017年 | 142篇 |
2016年 | 134篇 |
2015年 | 168篇 |
2014年 | 268篇 |
2013年 | 483篇 |
2012年 | 610篇 |
2011年 | 661篇 |
2010年 | 407篇 |
2009年 | 335篇 |
2008年 | 712篇 |
2007年 | 729篇 |
2006年 | 736篇 |
2005年 | 744篇 |
2004年 | 773篇 |
2003年 | 772篇 |
2002年 | 736篇 |
2001年 | 222篇 |
2000年 | 188篇 |
1999年 | 218篇 |
1998年 | 183篇 |
1997年 | 161篇 |
1996年 | 154篇 |
1995年 | 154篇 |
1994年 | 165篇 |
1993年 | 140篇 |
1992年 | 217篇 |
1991年 | 183篇 |
1990年 | 170篇 |
1989年 | 188篇 |
1988年 | 186篇 |
1987年 | 137篇 |
1986年 | 190篇 |
1985年 | 197篇 |
1984年 | 192篇 |
1983年 | 178篇 |
1982年 | 171篇 |
1981年 | 189篇 |
1980年 | 171篇 |
1979年 | 120篇 |
1978年 | 152篇 |
1977年 | 102篇 |
1976年 | 124篇 |
1975年 | 128篇 |
1974年 | 101篇 |
1973年 | 108篇 |
1972年 | 75篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
961.
PURPOSE: Staphylomatous thinning of the sclera and retina are among the numerous changes associated with the elongated eye of high myopia. We report a case of scleral and retinal transparency in high myopia in which ocular coherence tomography was used to measure retinal and scleral thickness in vivo. DESIGN: Observational case report. METHODS: The clinical presentation and evaluation of a case of scleral transparency in high myopia are presented. RESULTS: This case demonstrates numerous anatomical changes to the sclera and retina known to occur in association with high myopia. Initial evaluation by optical coherence tomography demonstrated a retinal thickness of 74 microm and a scleral thickness of 80 microm. CONCLUSIONS: Optical coherence tomography can be used to measure scleral and retinal thickness in vivo in a patient with high myopia. It is not known at this time what precautions are necessary in such a patient should intraocular surgery be required. 相似文献
962.
Globe DR Wu J Azen SP Varma R;Los Angeles Latino Eye Study Group 《Ophthalmology》2004,111(6):1141-1149
OBJECTIVE: To assess the association between presenting binocular visual acuity (VA) and self-reported visual function as measured by the 25-item National Eye Institute Visual Function Questionnaire (NEI-VFQ-25). DESIGN: A population-based, prevalence study of eye disease in Latinos 40 years and older residing in La Puente, California (Los Angeles Latino Eye Study [LALES]). PARTICIPANTS: Six thousand three hundred fifty-seven Latinos 40 years and older from 6 census tracts in La Puente. METHODS: All participants completed a standardized interview, including the NEI-VFQ-25 to measure visual functioning, and a detailed eye examination. Two definitions of visual impairment were used: (1) presenting binocular distance VA of 20/40 or worse and (2) presenting binocular distance VA worse than 20/40. Analysis of variance was used to determine any systematic differences in mean NEI-VFQ-25 scores by visual impairment. Regression analyses were completed (1) to determine the association of age, gender, number of systemic comorbidities, depression, and VA with self-reported visual function and (2) to estimate a visual impairment-related difference for each subscale based on differences in VA. MAIN OUTCOME MEASURES: The NEI-VFQ-25 scores in persons with visual impairment. RESULTS: Of the 5287 LALES participants with complete NEI-VFQ-25 data, 6.3% (including 20/40) and 4.2% (excluding 20/40) were visually impaired. In the visually impaired participants, the NEI-VFQ-25 subscale scores ranged from 46.2 (General Health) to 93.8 (Color Vision). In the regression model, only VA, depression, and number of comorbidities were significantly associated with all subscale scores (R(2) ranged from 0.09 for Ocular Pain to 0.33 for the composite score). For 9 of 11 subscales, a 5-point change was equivalent to a 1- or 2-line difference in VA. Relationships were similar regardless of the definition of visual impairment. CONCLUSION: In this population-based study of Latinos, the NEI-VFQ-25 was sensitive to differences in VA. A 5-point difference on the NEI-VFQ-25 seems to be a minimal criterion for a visual impairment-related difference. Self-reported visual function is essentially unchanged if the definition of visual impairment includes or excludes a VA of 20/40. 相似文献
963.
Leong SP 《Current treatment options in oncology》2004,5(3):185-194
Opinion statement Selective sentinel lymphadenectomy (SSL) should be considered a standard of care approach for staging patients with primary
invasive melanoma 1 mm or greater. It is essential that multidisciplinary teams should master the techniques of preoperative
lymphoscintigraphy, intraoperative lymphatic mapping, and pathologic evaluation of the sentinel lymph nodes (SLNs). An SLN
may be blue, hot, or any lymph node (LN) greater than 10% of the in-vivo count of the hottest LN. An enlarged or indurated
LN should be removed because it may contain metastatic cancer cells that block blue dye or radiotracer entry. Frozen sections
are not recommended. Surgeons who use isosulfan blue dye should be cognizant of treatment for a potentially fatal reaction.
Prophylactic LN dissection should not be performed if a SSL can be performed as a staging procedure. A complete LN dissection
is performed if the SLN is positive. It is important to follow the clinical outcome of patients undergoing SSL, thus its role
can be further defined. 相似文献
964.
Schmugge M Rand ML Bang KW Mody M Dunn MS Amankwah KS Blanchette VS Freedman J 《Pediatric research》2003,54(4):474-479
von Willebrand Factor (VWF) is important in platelet adhesion and shear-dependent platelet activation. We performed flow cytometric analyses of VWF binding to and activation of platelets from healthy neonates, children, and adults. Platelets from cord blood (n = 38; gestational age: 36-42 wk; birth weight: 2.4-5.1 kg), neonatal venous blood (n = 19; d 2-3 of life), children (n = 15; age: 1.5-16.3 y), and adults (n = 22; age: 18-55 y) were studied. Binding of VWF was assessed using an antihuman VWF polyclonal antibody and a FITC-conjugated secondary antibody. Platelet activation was determined by the expression of CD62P, CD63, CD41, CD42b, activated GPIIb/IIIa (PAC-1), procoagulant surface (as reflected by annexin V binding), and microparticle formation. Although the mean percentage of VWF-positive platelets was not significantly higher in unstimulated platelets from 2- to 3-d-old neonates, their platelets were more activated than those from adults, and there was a positive correlation of VWF binding with platelet activation (CD62P: r = 0.74, p < 0.001; annexin V: r = 0.46, p < 0.05). In adults, after in vitro activation of platelets with thrombin and ADP, VWF binding to platelets increased and correlated significantly with CD62P expression (r = 0.71, p < 0.001). VWF binding to unstimulated neonatal platelets was, however, higher than that to in vitro-stimulated platelets from adults at the same level of expression of platelet activation markers. Further studies are required to assess the mechanism and significance of VWF binding to activated platelets in the neonatal period. 相似文献
965.
Oddy WH Sly PD de Klerk NH Landau LI Kendall GE Holt PG Stanley FJ 《Archives of disease in childhood》2003,88(3):224-228
Aim: To examine the relation between the duration of breast feeding and morbidity as a result of respiratory illness and infection in the first year of life. Methods: Prospective birth cohort study of 2602 live born children ascertained through antenatal clinics at the major tertiary obstetric hospital in Perth, Western Australia. Main outcome measures were hospital, doctor, or clinic visits, and hospital admissions for respiratory illness and infection in the first year of life. Main exposure measures were the duration of predominant breast feeding (defined as the age other milk was introduced) and partial (any) breast feeding (defined as the age breast feeding was stopped). Main confounders were gender, gestational age less than 37 weeks, smoking in pregnancy, older siblings, maternal education, and maternal age. Results: Hospital, doctor, or clinic visits for four or more upper respiratory tract infections were significantly greater if predominant breast feeding was stopped before 2 months or partial breast feeding was stopped before 6 months. Predominant breast feeding for less than six months was associated with an increased risk for two or more hospital, doctor, or clinic visits and hospital admission for wheezing lower respiratory illness. Breast feeding for less than eight months was associated with a significantly increased risk for two or more hospital, doctor, or clinic visits or hospital admissions because of wheezing lower respiratory illnesses. Conclusions: Predominant breast feeding for at least six months and partial breast feeding for up to one year may reduce the prevalence and subsequent morbidity of respiratory illness and infection in infancy. 相似文献
966.
Szefler SJ 《Pediatric clinics of North America》2003,50(3):577-591
Based on the results of the long-term CAMP clinical trial in childhood asthma, the benefits of continuous long-term use of inhaled glucocorticoid on asthma control are clear. Studies are in progress to evaluate whether early intervention with inhaled glucocorticoids can alter the natural history of asthma. Indicators are now being defined to identify the patient at risk for persistent asthma and thus to identify candidates for early intervention. Given the right medication and the patient profile, it may be possible to induce remission or even a cure. Patients with severe asthma have low pulmonary function that is difficult to improve, however. It will be important to recognize patients at risk for severe asthma and to intervene more effectively to prevent asthma progression. None of these advances will be possible without a comprehensive approach to asthma care including the ready access to health care. Although it seems that the rise in asthma mortality and morbidity has reached a plateau, there are significant racial and ethic disparities in asthma health care use and mortality. The goal should now be to strive for a reduction in asthma morbidity and mortality. A high proportion of asthma morbidity among inner-city children may be related to nonadherence; therefore targeting management approaches to improve adherence could prove effective in reducing morbidity. Recommendations have been made to integrate available resources in the United States to improve overall asthma outcomes for children. 相似文献
967.
968.
Szilagyi PG Iwane MK Humiston SE Schaffer S McInerny T Shone L Jennings J Washington ML Schwartz B 《Archives of pediatrics & adolescent medicine》2003,157(2):191-195
OBJECTIVE: To measure the time currently spent by primary care practice personnel, and the examination room occupancy time for childhood influenza vaccination visits, to assess the practicality of annual influenza vaccination of all preschool children. SETTING: Seven primary care practices serving one fourth of the children living in Rochester, NY. PATIENTS: Ninety-two children seen for influenza vaccination visits in the 2000-2001 vaccination season. METHODS: Using a standardized protocol, practice staff measured the time spent on check-in, nurse or physician examination, and the actual influenza vaccination process. Waiting and "hands-on" times were determined, as well as total visit and room occupancy times. Nonparametric tests and multivariable models were used to analyze the time spent for components of the visits and to compare time spent by different age groups and practice types (suburban or urban). RESULTS: The median duration of the influenza vaccination visit was 14 minutes (25th to 75th percentiles range, 9-25 minutes) across the 7 practices, with visits to urban practices being longer (22 minutes) than visits to suburban practices (9 minutes). Eighty percent of patient time involved waiting, primarily in examination rooms. The major components of influenza vaccination visits included waiting room time (4 minutes in suburban practices vs 8 minutes in urban practices; P<.01), and time in the examination room (5 minutes vs 14 minutes, respectively; P<.001), during which only 1 to 2 minutes (for both suburban and urban practices) were for hands-on vaccinations. Only 5% of visits were examined by a physician or nurse practitioner. Visit times did not vary by age. CONCLUSIONS: Although the personnel time for influenza vaccination visits was short, there was substantial patient waiting and long occupancy of examination rooms. If universal influenza vaccination is to be efficiently managed in primary care practices, it may be necessary to implement "vaccination clinics" or sessions in which large numbers of children are scheduled for influenza vaccinations at times when adequate rooms and dedicated nursing staff are available. 相似文献
969.
Faith MS Heshka S Keller KL Sherry B Matz PE Pietrobelli A Allison DB 《Archives of pediatrics & adolescent medicine》2003,157(9):926-932
BACKGROUND: Certain mother-child feeding patterns (MCFPs) may promote childhood obesity and/or disordered eating. OBJECTIVES: To assess the demographic correlates of MCFPs and to test whether differences in MCFPs are associated with child body mass index (BMI; calculated as weight in kilograms divided by the square of height in meters) z scores in a population-based study. DESIGN: A secondary analysis of the National Longitudinal Survey of Youth main and child cohorts was conducted on more than 1000 Hispanic, African American, and non-Hispanic/non-African American children, aged 3 to 6 years. The MCFPs were measured by means of 3 interview questions probing mother-allotted child food choice, child compliance during meals, and child obedience during meals. RESULTS: Mothers of non-Hispanic/non-African American children allotted greater food choice than mothers of African American or Hispanic children. Maternal BMI and other demographic measures were unrelated to MCFPs. The lowest levels of mother-allotted child food choice and child eating compliance were associated with reduced child BMI, with mean BMI z scores of -0.36 and -0.41, respectively. Effect sizes were small, however, and MCFPs did not discriminate children who were overweight or at risk for being overweight from children who were not (P>.05). CONCLUSIONS: Feeding strategies providing the least child food choice were associated with reduced child BMI. However, MCFPs did not relate to child overweight status. 相似文献
970.
An inhibitor of interferon antiviral activity, which is absent in healthy HIV-seronegative persons, was detected in the sera of all 29 HIV-seropositive study participants. The relationship of the level of interferon inhibitor to CD4 count and HIV-RNA copy number was statistically significant in distinct models. Levels of interferon inhibitor declined by an average of 41-60% in patients who underwent a change in anti-retroviral therapy. Interferon inhibitor levels appear to decline as CD4 cell count rises and HIV-RNA levels fall. This suggests that interferon inhibitor may have a significant role in the host immune response to HIV infection. 相似文献