全文获取类型
收费全文 | 1477篇 |
免费 | 134篇 |
国内免费 | 8篇 |
专业分类
耳鼻咽喉 | 1篇 |
儿科学 | 81篇 |
妇产科学 | 65篇 |
基础医学 | 149篇 |
口腔科学 | 58篇 |
临床医学 | 147篇 |
内科学 | 446篇 |
皮肤病学 | 8篇 |
神经病学 | 99篇 |
特种医学 | 83篇 |
外科学 | 175篇 |
综合类 | 39篇 |
预防医学 | 113篇 |
眼科学 | 26篇 |
药学 | 60篇 |
中国医学 | 1篇 |
肿瘤学 | 68篇 |
出版年
2023年 | 11篇 |
2022年 | 12篇 |
2021年 | 21篇 |
2020年 | 20篇 |
2019年 | 29篇 |
2018年 | 24篇 |
2017年 | 15篇 |
2016年 | 20篇 |
2015年 | 46篇 |
2014年 | 52篇 |
2013年 | 46篇 |
2012年 | 62篇 |
2011年 | 101篇 |
2010年 | 54篇 |
2009年 | 49篇 |
2008年 | 54篇 |
2007年 | 50篇 |
2006年 | 61篇 |
2005年 | 61篇 |
2004年 | 73篇 |
2003年 | 50篇 |
2002年 | 38篇 |
2001年 | 32篇 |
2000年 | 35篇 |
1999年 | 41篇 |
1998年 | 35篇 |
1997年 | 27篇 |
1996年 | 25篇 |
1995年 | 22篇 |
1994年 | 27篇 |
1993年 | 23篇 |
1992年 | 28篇 |
1991年 | 29篇 |
1990年 | 28篇 |
1989年 | 30篇 |
1988年 | 28篇 |
1987年 | 32篇 |
1986年 | 23篇 |
1985年 | 23篇 |
1984年 | 18篇 |
1983年 | 14篇 |
1982年 | 15篇 |
1979年 | 21篇 |
1978年 | 8篇 |
1977年 | 12篇 |
1975年 | 8篇 |
1974年 | 7篇 |
1973年 | 10篇 |
1970年 | 8篇 |
1966年 | 10篇 |
排序方式: 共有1619条查询结果,搜索用时 15 毫秒
81.
82.
A laparoscopic technique for obtaining ovarian cortical biopsy specimens for fertility conservation in patients with cancer 总被引:10,自引:0,他引:10
Meirow D Fasouliotis SJ Nugent D Schenker JG Gosden RG Rutherford AJ 《Fertility and sterility》1999,71(5):948-951
OBJECTIVE: To evaluate the efficacy of a newly designed round biopter as a practical and safe method for collecting ovarian tissue for cryopreservation in young women with cancer before chemotherapy. DESIGN: Prospective study of young women volunteering for research (Leeds, United Kingdom) and patients with cancer (Jerusalem, Israel and Leeds, United Kingdom) undergoing laparoscopic ovarian cortical tissue biopsy and cryopreservation before administration of high-dose radiochemotherapy. SETTING: Two university-based tertiary referral centers of oncology and gynecology (Hadassah Medical Center, Israel; Leeds General Infirmary, United Kingdom). PATIENT(S): Twenty female volunteers undergoing routine laparoscopic gynecologic procedures (age, 25-34 years) and 20 young women (age, 11-30 years) with advanced cancer requiring potentially sterilizing radiochemotherapy. INTERVENTION(S): Cortical ovarian tissue biopsies performed under laparoscopy with use of the round biopter. RESULT(S): The laparoscopic sampling procedure was uncomplicated in all cases. In treated patients, five to six samples were obtained (5 mm in diameter; 2-3 mm in depth) using the round biopter, and radiochemotherapy was administered without delay. In volunteers, no adhesions were noted at repeat laparoscopy (9 patients). All biopsy specimens were cryopreserved, and histologic examination confirmed the presence of many primordial follicles. CONCLUSION(S): Laparoscopic ovarian biopsy performed with the round biopter is a safe and efficient method for collecting ovarian tissue for cryopreservation in patients with cancer. 相似文献
83.
84.
85.
Occlusive platelet thrombi periodically form in mechanically stenosed dog coronary arteries producing cyclical blood flow reductions occurring over 4-7 min. Cyclical coronary flow reductions are exacerbated by IV epinephrine 0.4 microgram.kg-1.min-1 for 15 min. These flow reductions can be abolished by known inhibitors of platelet function. This study assesses the effect of halothane, isoflurane, and enflurane on spontaneous- and epinephrine-exacerbated cyclical coronary flow reductions. Twenty-three open-chest dogs [1% halothane (n = 5), 0.5% halothane (n = 5), 0.25% halothane (n = 3), 1.5% isoflurane (n = 5), and 2.0% enflurane (n = 5)] with a mechanically stenosed coronary artery showed cyclical blood flow reductions. With 1.0% halothane administration, spontaneous cyclical blood flow reductions were abolished (n = 5), whereas during administration of isoflurane 1.5% (n = 5) and enflurane 2.0% (n = 5) cyclical flow reductions and myocardial ischemia continued. Subsequent administration of halothane in the isoflurane and enflurane groups showed abolition of coronary flow reductions in all animals (n = 10). In eight animals a 15-min epinephrine infusion (0.4 microgram.kg-1.min-1) was given following a control period and again following abolition of coronary flow reductions by halothane 0.5% (n = 5) and halothane 0.25% (n = 3). The magnitude of cyclical blood flow reductions (difference between initial and final coronary flow level of each flow reduction) changed from 52 +/- 11 to 61 +/- 12 ml/min (NS), and frequency increased from 0.37 to 0.57/min (P less than 0.05, n = 8) during epinephrine infusion.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
86.
Graber MA Hartz A James P Nugent A Green MD 《The Journal of the American Board of Family Practice / American Board of Family Practice》2005,18(6):453-458
BACKGROUND: Physician experts hired and prepared by litigants provide most information on standard of care for medical malpractice cases. Because this information may not be objective or accurate, we examined the feasibility and potential value of surveying peer physicians to assess standard of care. METHODS: The survey method was evaluated for a medical malpractice case involving a patient hospitalized with abdominal pain. An abstract of the medical record was created that included the patient characteristics and physician decisions most likely to influence patient outcome. The abstract and questionnaire were sent to 16 academic family physicians and to 20 randomly chosen primary care physicians in Iowa who practiced in communities of similar size to the defendant's community. RESULTS: All 16 academic and 18 (90%) community physicians completed the survey. All respondents judged the patient as presenting with an acute abdomen, and 89% of the community physicians and 100% of the academic physicians judged the care as below standard. More than half the physicians surveyed listed the autopsy diagnosis (perforated ulcer) in their differential. CONCLUSION: Surveys of randomly selected physicians are feasible to perform for medical malpractice cases. A pro-physician bias has little if any influence on the results. 相似文献
87.
Is bacterial vaginosis a stronger risk factor for preterm birth when it is diagnosed earlier in gestation? 总被引:5,自引:0,他引:5
Klebanoff MA Hillier SL Nugent RP MacPherson CA Hauth JC Carey JC Harper M Wapner RJ Trout W Moawad A Leveno KJ Miodovnik M Sibai BM Vandorsten JP Dombrowski MP O'Sullivan MJ Varner M Langer O;National Institute of Child Health Human Development Maternal-Fetal Medicine Units Network 《American journal of obstetrics and gynecology》2005,192(2):470-477
OBJECTIVE: It is stated commonly that the earlier in pregnancy bacterial vaginosis is diagnosed, the greater is the increase in risk of preterm birth compared with women without bacterial vaginosis. However, this contention is based on small numbers of women. STUDY DESIGN: In this analysis of 12,937 women who were screened for bacterial vaginosis as part of a previously conducted clinical trial, the odds ratio of preterm birth (<7 weeks of gestation) for asymptomatic bacterial vaginosis-positive versus bacterial vaginosis-negative women was evaluated among women who were screened from 8 to 22 weeks of gestation. RESULTS: The odds ratio of preterm birth among bacterial vaginosis-positive versus bacterial vaginosis-negative women ranged from 1.1 to 1.6 and did not vary significantly according to the gestational age at which bacterial vaginosis was screened. The odds ratio for preterm birth did not vary significantly by gestational age at diagnosis when bacterial vaginosis was subdivided into Gram stain score 7 to 8 or 9 to 10. CONCLUSION: Although bacterial vaginosis was associated with an increased risk of preterm birth, the gestational age at which bacterial vaginosis was screened for and diagnosed did not influence the increase. 相似文献
88.
Frontotemporal alterations in pediatric bipolar disorder: results of a voxel-based morphometry study
Dickstein DP Milham MP Nugent AC Drevets WC Charney DS Pine DS Leibenluft E 《Archives of general psychiatry》2005,62(7):734-741
CONTEXT: While numerous magnetic resonance imaging (MRI) studies have evaluated adults with bipolar disorder (BPD), few have examined MRI changes in children with BPD. OBJECTIVE: To determine volume alterations in children with BPD using voxel-based morphometry, an automated MRI analysis method with reduced susceptibility to various biases. A priori regions of interest included amygdala, accumbens, hippocampus, dorsolateral prefrontal cortex (DLPFC), and orbitofrontal cortex. DESIGN: Ongoing study of the pathophysiology of pediatric BPD. SETTING: Intramural National Institute of Mental Health; approved by the institutional review board.Patients Pediatric subjects with BPD (n = 20) with at least 1 manic or hypomanic episode meeting strict DSM-IV criteria for duration and elevated, expansive mood. Controls (n = 20) and their first-degree relatives lacked psychiatric disorders. Groups were matched for age and sex and did not differ in IQ. MAIN OUTCOME MEASURES: With a 1.5-T MRI machine, we collected 1.2-mm axial sections (124 per subject) with an axial 3-dimensional spoiled gradient recalled echo in the steady state sequence. Image analysis was by optimized voxel-based morphometry. RESULTS: Subjects with BPD had reduced gray matter volume in the left DLPFC. With a less conservative statistical threshold, additional gray matter reductions were found in the left accumbens and left amygdala. No difference was found in the hippocampus or orbitofrontal cortex. CONCLUSIONS: Our results are consistent with data implicating the prefrontal cortex in emotion regulation, a process that is perturbed in BPD. Reductions in amygdala and accumbens volumes are consistent with neuropsychological data on pediatric BPD. Further study is required to determine the relationship between these findings in children and adults with BPD. 相似文献
89.
Risk factors for adverse outcomes in spontaneous versus assisted conception twin pregnancies 总被引:7,自引:0,他引:7
Luke B Brown MB Nugent C Gonzalez-Quintero VH Witter FR Newman RB 《Fertility and sterility》2004,81(2):315-319
OBJECTIVE: To evaluate risk factors for adverse outcomes in spontaneous vs. assisted conception twin pregnancies. DESIGN: Historical cohort study. SETTING: Four academic tertiary medical centers. PATIENT(S): Women with twin pregnancies, including 2,143 spontaneous and 424 assisted conception; 2,492 nonreduced and 75 reduced. INTERVENTION(S): None (observational). MAIN OUTCOME MEASURE(S): Preeclampsia, preterm premature rupture of membranes, birth <32 weeks and <30 weeks, low birth weight, very low birth weight, and slowed midgestation fetal growth (<10th percentile between 20 and 28 weeks). RESULT(S): Among nonreduced pregnancies, assisted conception was not significantly associated with any adverse outcomes; among nulliparas, the risk for preeclampsia was increased regardless of method of conception; among spontaneous conceptions, the risks for preterm premature rupture of membranes, low birth weight, very low birth weight, and slowed midgestation fetal growth were increased. Among all pregnancies, fetal reduction increased risks for birth <32 weeks and <30 weeks, low birth weight, very low birth weight, and slowed midgestation fetal growth. Among nulliparas with assisted conceptions, fetal reduction increased the risks for birth <30 weeks, very low birth weight, and slowed midgestation fetal growth. CONCLUSION(S): These findings indicate that in twin pregnancies, assisted conception is not a risk factor for adverse outcomes, but rather specific factors that are more common among these pregnancies, such as nulliparity and fetal reduction, increase risks. 相似文献
90.
O'Rourke DJ Quinton HB Piper W Hernandez F Morton J Hettleman B Hearne M Nugent W O'Connor GT Malenka DJ;Northern New England Cardiovascular Disease Study Group 《The Annals of thoracic surgery》2004,78(2):466-470