全文获取类型
收费全文 | 12339篇 |
免费 | 938篇 |
国内免费 | 97篇 |
专业分类
耳鼻咽喉 | 25篇 |
儿科学 | 1932篇 |
妇产科学 | 2762篇 |
基础医学 | 891篇 |
口腔科学 | 139篇 |
临床医学 | 1133篇 |
内科学 | 672篇 |
皮肤病学 | 88篇 |
神经病学 | 341篇 |
特种医学 | 94篇 |
外科学 | 420篇 |
综合类 | 1455篇 |
一般理论 | 3篇 |
预防医学 | 2306篇 |
眼科学 | 69篇 |
药学 | 699篇 |
3篇 | |
中国医学 | 196篇 |
肿瘤学 | 146篇 |
出版年
2024年 | 30篇 |
2023年 | 233篇 |
2022年 | 393篇 |
2021年 | 556篇 |
2020年 | 500篇 |
2019年 | 538篇 |
2018年 | 501篇 |
2017年 | 569篇 |
2016年 | 549篇 |
2015年 | 491篇 |
2014年 | 902篇 |
2013年 | 1051篇 |
2012年 | 722篇 |
2011年 | 833篇 |
2010年 | 685篇 |
2009年 | 647篇 |
2008年 | 577篇 |
2007年 | 586篇 |
2006年 | 504篇 |
2005年 | 431篇 |
2004年 | 332篇 |
2003年 | 267篇 |
2002年 | 198篇 |
2001年 | 145篇 |
2000年 | 144篇 |
1999年 | 100篇 |
1998年 | 76篇 |
1997年 | 74篇 |
1996年 | 59篇 |
1995年 | 61篇 |
1994年 | 55篇 |
1993年 | 51篇 |
1992年 | 41篇 |
1991年 | 45篇 |
1990年 | 42篇 |
1989年 | 28篇 |
1988年 | 44篇 |
1987年 | 29篇 |
1986年 | 32篇 |
1985年 | 32篇 |
1984年 | 39篇 |
1983年 | 23篇 |
1982年 | 28篇 |
1981年 | 23篇 |
1980年 | 18篇 |
1979年 | 13篇 |
1978年 | 13篇 |
1977年 | 14篇 |
1976年 | 13篇 |
1973年 | 8篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
21.
Pulmonary effects of closure of patent ductus arteriosus in premature infants with severe respiratory distress syndrome 总被引:1,自引:0,他引:1
The pulmonary effects of closure of a patent ductus arteriosus (PDA) were investigated in 11 premature infants with severe respiratory distress syndrome. Successful closure of a PDA did not improve the short-term severity of pulmonary disease (24 and 48 h after treatment) as judged by the arterial/alveolar oxygen tension ratio or the amount of ventilatory support. Also, pulmonary mechanics measured 24 h before, 24 and 48 h after treatment, were not statistically different.Conclusion Infants with severe respiratory disease requiring high ventilation pressure and high oxygen concentration, where structural changes in the lungs are already established, will rarely show short-term improvement in pulmonary disease as a result of closure of a PDA. The overall clinical condition may, however, improve as a result of reduced cardiovascular strain. Earlier treatment of a PDA could reduce the ventilation period and the possible risk of developing chronic lung disease. 相似文献
22.
ABSTRACT: Background: The percentage of United States’ births delivered by cesarean section has increased rapidly in recent years, even for women considered to be at low risk for a cesarean section. The purpose of this paper is to examine infant and neonatal mortality risks associated with primary cesarean section compared with vaginal delivery for singleton full‐term (37–41 weeks’ gestation) women with no indicated medical risks or complications. Methods: National linked birth and infant death data for the 1998–2001 birth cohorts (5,762,037 live births and 11,897 infant deaths) were analyzed to assess the risk of infant and neonatal mortality for women with no indicated risk by method of delivery and cause of death. Multivariable logistic regression was used to model neonatal survival probabilities as a function of delivery method, and sociodemographic and medical risk factors. Results: Neonatal mortality rates were higher among infants delivered by cesarean section (1.77 per 1,000 live births) than for those delivered vaginally (0.62). The magnitude of this difference was reduced only moderately on statistical adjustment for demographic and medical factors, and when deaths due to congenital malformations and events with Apgar scores less than 4 were excluded. The cesarean/vaginal mortality differential was widespread, and not confined to a few causes of death. Conclusions: Understanding the causes of these differentials is important, given the rapid growth in the number of primary cesareans without a reported medical indication. (BIRTH 33:3 September 2006) 相似文献
23.
Ultrasonography in the detection of cervical incompetency 总被引:2,自引:0,他引:2
Mario Podobnik Milan Buli Nikola Smiljanic Josip Bistri
ki 《Journal of clinical ultrasound : JCU》1988,16(6):383-391
In 80 pregnancies with clinical and ultrasonic signs of cervical incompetency, the length of the cervix and the thickness of the anterior wall of a lower uterine segment have been evaluated ultrasonically. We have also measured the width of the endocervical canal and studied the prolapse of fetal membranes (with fetal parts) into the endocervical canal. We evaluated these same parameters in 80 healthy pregnancies. The length of the cervix, the thickness of the anterior wall of a lower uterine segment, and the width of the endocervical canal were followed longitudinally in the patients from the 10th to the 36th gestation week. No statistically significant differences between age groups were found. In four age groups at risk for cervical incompetency, cervical lengths and wall thickness were significantly different (p less than 0.001) from those in comparable controls. Forty-five percent of the patients in the at-risk group, with cervical cerclage, delivered at 37.3 (range: 32 to 41) weeks and 6.25% of pregnancies ended in abortion when the amniotic membrane herniated into the cervical canal, with or without some part of the fetus. 相似文献
24.
极低出生体重儿两种喂养效果观察 总被引:4,自引:0,他引:4
目的:探讨极低出生体重儿(VLBW)的早期微量持续鼻饲喂养(CNG)与间断鼻饲喂养(ING)的喂养耐受性及喂养效果.方法:将60例VLBW进行随机分组,CNG组起始奶量1-2ml/h,以后泵速增加1-2ml/h.ING组奶量以1-2ml/kg开始, 以后每天增加1-2ml/kg/次.所有VLBW均同时进行部分静脉营养,直至达到完全胃肠道喂养时间(FEF).对比两组喂养不耐受性、达到FEF、停止静脉补液时间及黄疸持续时间.结果:CNG组较ING组患儿发生腹胀、呕吐者明显减少(P<0.05),黄疸持续时间、吸吮动作出现时间及住院时间较对照组明显缩短(P<0.05),但两组体重增长情况统计学无差异(P>0.05).结论:CNG更适合VLBW的早期微量喂养. 相似文献
25.
Cardiovascular malformations and organic solvent exposure during pregnancy in Finland 总被引:2,自引:0,他引:2
In order to investigate the possible association between cardiovascular malformations and maternal exposure to organic solvents during the first trimester of pregnancy, 569 cases and 1,052 controls were retrospectively studied. The cases represented all infants with diagnosed cardiovascular malformations born in Finland in 1982-1984, and the controls were randomly selected from all normal births in the country during the same period. All mothers were interviewed approximately 3 months after delivery by a midwife using a structured questionnaire. Exposures to organic solvents at work during the first trimester of pregnancy were slightly more prevalent among the mothers of affected infants (10.4%) than among those of controls (7.8%). Logistic regression analysis of exposure to organic solvents showed an adjusted relative odds ratio of 1.3 (95% confidence interval, 0.8-2.2). In the analysis of ventricular septal defect, exposure to organic solvents showed an adjusted relative odds ratio of 1.5 (95% confidence interval, 1.0-3.7). 相似文献
26.
Dr. S. H. Zinner 《International urogynecology journal》1990,1(3):146-149
Bacteriuria in pregnancy is now easily detected by various techniques adapted to the office setting. It is importtant to screen for bacteriuria in pregnancy because 3%–10% of pregnant women will be positive for occult infection. Up to 30% thus infected will subsequently develop pyelonephritis later in pregnancy, which in turn is associated with premature labor and delivery. This entity must be detected and treated as early as possible in pregnancy to prevent these adverse effects.Presented at the Zambon Symposium on Bacteriuria in Pregnancy, International Urogynecological Association Annual Meeting, Riva del Garda, Italy, September 13, 1989.Dedicated to the memory of Edward H. Kass, MD, PhD. 相似文献
27.
NAOTO TAKAHASHI HIROSHI NISHIDA TOSHIHIKO ARAI YOSHIO KANEDA 《Pediatrics international》1995,37(3):341-346
Four infants with severe intrauterine growth retardation (IUGR) weighing less than 1000 g at birth developed heart failure and died in our unit, where heart failure of IUGR infants is the main reason of death in extremely low birth-weight infants. The causes of their heart failure are one of the main themes in current neonatal medicine. The subjects of this study were four small for gestational age infants; all died due to heart failure 5 to 10 days after birth. Microscopic specimens of hearts from autopsies were evaluated with respect to the following characteristics: thickness of myocardial fibers, maturation of nuclei, presence of dysgenesis or necrosis in myocardium, and amount of glycogen in the heart. Neither dysgenesis nor infarction of the heart was found but hypoplasia in myocardial fibers and decreased glycogen levels were observed. Maturation delay in myocytes' nuclei did not appear to be severe. We conclude that these infants' hearts failed to adapt to postnatal hemodynamic changes because of inadequate myocardial function and inadequate glycogen reserves. 相似文献
28.
以296例胎膜早破(PROM)作为研究对象,并以350例无PROM作对照,探讨PROM对母婴的影响。结果显示:PROM组难产率为56.08%,产褥病率4.05%,早产率为5.40%,胎儿窘迫率为13.00%,新生儿窒息率为4.33%,新生儿肺炎发生率为3.66%,均明显高于对照组,统计学处理后有显著或极显著性差异(P<0.05,P<0.01)。而且,PROM隐惹期小于24小时的产褥病率为2.29%;大于24小时的产褥病率则为8.97%(P<0.05)。本文提示,应积极预防胎膜早破,一旦出现胎膜早破,宜在6小时内使用抗生素预防感染,并加强母儿监测。 相似文献
29.
目的对比观察剖腹产选用连续硬膜外麻醉时,辅助麻醉用药镇静及对牵拉反应抑制效果。方法选择行剖腹产手术产妇60例在硬膜外麻醉效果满意后,随机分两组各30例。Ⅰ组:哌替啶50mg,异丙嗪25mg单次静注。Ⅱ组:氯胺酮28.5mg,咪达唑仑1.42mg单次静注。分组记录用药前,1min,5min,15min及术毕产妇SpO2、RR、HR、MAP值;记录手术时间、术毕苏醒例数、术中恶心躁动例数;记录术毕产妇OAA/S评分;记录新生儿娩出时Apger评分。结果两组术中镇静、抑制牵拉反应效果均满意。两组RR、BP、HR、SpO2均平稳;术毕两组OAA/S评分均为4-5分;新生儿Apger评分均正常。结论两组方法效果确切,对产妇和新生儿安全。 相似文献
30.
Cardiovascular malformations, work attendance, and occupational exposures during pregnancy in Finland 总被引:1,自引:0,他引:1
J Tikkanen K Kurppa H Timonen P C Holmberg E Kuosma K Rantala 《American journal of industrial medicine》1988,14(2):197-204
To explore for associations between occupational factors and cardiovascular malformations, information on the parents of 160 infants with cardiovascular malformations and 160 control parents was studied. The case infants had been reported consecutively to the Finnish Register of Congenital Malformations. All mothers were interviewed identically after delivery, using both open and pro forma questions about detailed work tasks, exposures, and leisure activities during pregnancy. The interview information was evaluated blindly. Neither parental occupational titles nor maternal working per se gave new clues to the teratogenic risk; nor did shift working, wearing of personal protective equipment, or the mother's own opinion on exposures during pregnancy. Identified occupational exposures, as categorized by an industrial hygienist, showed no remarkable associations to cardiovascular malformations. Few mothers were exposed substantially to specific occupational hazards. Comparing mothers who used medications in the first trimester with those who did not showed an odds ratio of 2.2 (95% confidence interval 1.3-3.9) when adjusted for potential confounding by multivariate logistic methods. 相似文献