全文获取类型
收费全文 | 1633篇 |
免费 | 126篇 |
国内免费 | 23篇 |
专业分类
耳鼻咽喉 | 3篇 |
儿科学 | 132篇 |
妇产科学 | 33篇 |
基础医学 | 147篇 |
口腔科学 | 45篇 |
临床医学 | 167篇 |
内科学 | 385篇 |
皮肤病学 | 19篇 |
神经病学 | 120篇 |
特种医学 | 150篇 |
外科学 | 165篇 |
综合类 | 35篇 |
一般理论 | 5篇 |
预防医学 | 102篇 |
眼科学 | 106篇 |
药学 | 77篇 |
肿瘤学 | 91篇 |
出版年
2023年 | 9篇 |
2022年 | 8篇 |
2021年 | 7篇 |
2019年 | 24篇 |
2018年 | 15篇 |
2017年 | 17篇 |
2016年 | 16篇 |
2015年 | 32篇 |
2014年 | 28篇 |
2013年 | 50篇 |
2012年 | 49篇 |
2011年 | 71篇 |
2010年 | 56篇 |
2009年 | 46篇 |
2008年 | 43篇 |
2007年 | 70篇 |
2006年 | 52篇 |
2005年 | 58篇 |
2004年 | 42篇 |
2003年 | 43篇 |
2002年 | 43篇 |
2001年 | 47篇 |
2000年 | 52篇 |
1999年 | 46篇 |
1998年 | 55篇 |
1997年 | 52篇 |
1996年 | 41篇 |
1995年 | 26篇 |
1994年 | 27篇 |
1993年 | 20篇 |
1992年 | 43篇 |
1991年 | 44篇 |
1990年 | 43篇 |
1989年 | 47篇 |
1988年 | 59篇 |
1987年 | 45篇 |
1986年 | 46篇 |
1985年 | 38篇 |
1984年 | 35篇 |
1983年 | 29篇 |
1982年 | 32篇 |
1981年 | 23篇 |
1980年 | 9篇 |
1979年 | 29篇 |
1978年 | 11篇 |
1977年 | 15篇 |
1976年 | 9篇 |
1972年 | 8篇 |
1969年 | 10篇 |
1968年 | 6篇 |
排序方式: 共有1782条查询结果,搜索用时 359 毫秒
991.
992.
The fetal programming theory that birth weight contributes to blood pressure or body size in later life is examined in this study. A prospective longitudinal study was conducted on subjects who were examined as newborns and prospectively interviewed and re-examined at 11 to 14 years old. Low birth weight (<2500 g) was present in 36% of the sample. The adolescent examination included measurements of blood pressure (BP), both auscultation and oscillometric methods; anthropometrics (height, weight, and body mass index [BMI]); health status; and health behaviors. Data were analyzed on 250 subjects. Correlation coefficients of birth weight with all BP measures were nonsignificant, except for the last auscultated diastolic BP (r=0.19, P<0.01), which had a positive relationship. The simple correlation coefficients of birth weight with adolescent body size were significant and positive for weight and BMI. After multiple linear regression analyses with adjustments for age, Tanner stage, and gestational age, there was no significant effect of birth weight on adolescent weight or BMI. No significant correlations were detected for ponderal index at birth with adolescent measures. This study, which includes a substantial portion of low-birth-weight cases (36%), indicates that birth weight does not correlate negatively with later BP. These results do not support the low-birth-weight theory and indicate that childhood factors that are more proximal have a greater effect on adolescent BP than intrauterine factors. 相似文献
993.
Alcohol, administered acutely, is known to cause CO(2) hyposensitivity. CO(2) hypersensitivity associated with anxiogenic hyperventilation (HV) could reasonably be expected to emerge as an opponent process upon withdrawal from chronic alcohol use. To test this hypothesis, we applied two well-known methods to quantify CO(2) sensitivity in recently detoxified alcohol-dependent individuals and never alcohol-disordered individuals who are social drinkers. We found that the alcoholic group exhibited significantly greater CO(2) sensitivity than did controls in response to both challenges. Indirect evidence of chronic HV was also obtained. These findings implicate the effect of chronic alcohol use on CNS-based CO(2) sensitivity in heightening the vulnerability to disturbing anxiety symptoms and syndromes exhibited by alcoholic individuals. Future work must verify that pathological drinking actually causes the dysregulated respiratory responding observed in this study as is inferred in our conclusions. 相似文献
994.
Mean doses of ionizing radiation, absorbed by children in the Byelarus Republic, were evaluated by EPR dosimetry of tableted samples of milk teeth enamel. A relationship between the doses absorbed by the children and density of radionuclide contamination of the territory of residence was detected. Based on the mean absorbed doses, doses which can be absorbed during 70 years of life were estimated. 相似文献
995.
Kushner I 《Cleveland Clinic journal of medicine》2001,68(6):535-537
Epidemiologic studies have revealed that minimal acute-phase changes predict poor prognoses in many conditions and predict disability and mortality in the elderly. These findings have usually been interpreted to indicate that inflammatory processes of some kind play a role in these situations. In fact, a minimal acute-phase response does not necessarily establish the existence of an inflammatory process but may also reflect a variety of noninflammatory states, including obesity, sleep disturbance, depression, chronic fatigue, and low levels of physical activity. I propose that a minimal acute-phase response may also be a marker of biologic aging, a condition known to predispose to poor prognoses and to death. 相似文献
996.
997.
998.
999.
1000.
EA Mitchell PG Tuohy JM Brunt JM Thompson MS Clements AW Stewart RP Ford BJ Taylor 《Pediatrics》1997,100(5):835-840
OBJECTIVES: To identify the risk factors for sudden infant death syndrome (SIDS) following a national campaign to prevent SIDS. METHODS: For 2 years (October 1, 1991 through September 30, 1993) data were collected by community child health nurses on all infants born in New Zealand at initial contact and at 2 months. RESULTS: There were 232 SIDS cases in the postneonatal age group (2.0/1000 live births) and these were compared with 1200 randomly selected control subjects. Information was available for 127 cases (54.7%) and 922 (76.8%) of controls. The previously identified modifiable risk factors were examined. The prevalence of prone sleeping position of the infant was very low (0.7% at initial contact and 3. 0% at 2 months), but was still associated with an increased risk of SIDS. In addition, the side sleeping position was also found to have an increased risk of SIDS compared with the supine sleeping position (at 2 months: adjusted odds ratio (OR) = 6.57; 95% confidence interval (CI) = 1.71, 25.23). Maternal smoking was found to be the major risk factor for SIDS. Bed sharing was also associated with an increased risk of SIDS. There was an interaction between maternal smoking and bed sharing on the risk of SIDS. Compared with infants not exposed to either bed sharing or maternal smoking, the adjusted OR for infants of mothers who smoked was 5.01 (95% CI = 2.01, 12.46) for bed sharing at the initial contact and 5.02 (95% CI = 1.05, 24. 05) for bed sharing at 2 months. In this study breastfeeding was not associated with a statistically significant reduction in the risk of SIDS. The other risk factors for SIDS identified were: unmarried mother, leaving school at a younger age, young mother, greater number of previous pregnancies, late attendance for antenatal care, smoking in pregnancy, male infant, Maori ethnicity, low birth weight, and shorter gestation. CONCLUSIONS: After adjustment for potential confounders, prone and side sleeping positions, maternal smoking, and the joint exposure to bed sharing and maternal smoking were associated with statistically significant increased risk of SIDS. A change from the side to the supine sleeping position could result in a substantial reduction in SIDS. Maternal smoking is common in New Zealand and with the reduction in the prevalence of prone sleeping position is now the major risk factor in this country. However, smoking behavior has been difficult to change. Bed sharing is also a major factor but appears only to be a risk to infants of mothers who smoke. Addressing bed sharing among mothers who smoke could reduce SIDS by at least one third. Breastfeeding did not appear to offer a statistically significant reduction in SIDS risk after adjustment of potential confounders, but as breastfeeding rates are comparatively good in New Zealand, this result should be interpreted with caution as the power of this study to detect a benefit is small. 相似文献