全文获取类型
收费全文 | 6444篇 |
免费 | 460篇 |
国内免费 | 15篇 |
专业分类
耳鼻咽喉 | 49篇 |
儿科学 | 201篇 |
妇产科学 | 155篇 |
基础医学 | 693篇 |
口腔科学 | 97篇 |
临床医学 | 953篇 |
内科学 | 1284篇 |
皮肤病学 | 64篇 |
神经病学 | 592篇 |
特种医学 | 132篇 |
外科学 | 997篇 |
综合类 | 97篇 |
一般理论 | 27篇 |
预防医学 | 711篇 |
眼科学 | 64篇 |
药学 | 376篇 |
中国医学 | 9篇 |
肿瘤学 | 418篇 |
出版年
2023年 | 77篇 |
2022年 | 127篇 |
2021年 | 296篇 |
2020年 | 138篇 |
2019年 | 257篇 |
2018年 | 278篇 |
2017年 | 166篇 |
2016年 | 157篇 |
2015年 | 158篇 |
2014年 | 227篇 |
2013年 | 323篇 |
2012年 | 431篇 |
2011年 | 479篇 |
2010年 | 226篇 |
2009年 | 206篇 |
2008年 | 337篇 |
2007年 | 312篇 |
2006年 | 276篇 |
2005年 | 289篇 |
2004年 | 263篇 |
2003年 | 219篇 |
2002年 | 196篇 |
2001年 | 86篇 |
2000年 | 79篇 |
1999年 | 54篇 |
1998年 | 50篇 |
1997年 | 39篇 |
1996年 | 41篇 |
1995年 | 39篇 |
1994年 | 23篇 |
1993年 | 26篇 |
1992年 | 65篇 |
1991年 | 68篇 |
1990年 | 78篇 |
1989年 | 58篇 |
1988年 | 50篇 |
1987年 | 67篇 |
1986年 | 69篇 |
1985年 | 36篇 |
1984年 | 34篇 |
1983年 | 37篇 |
1982年 | 29篇 |
1981年 | 25篇 |
1979年 | 49篇 |
1978年 | 30篇 |
1977年 | 26篇 |
1976年 | 25篇 |
1973年 | 23篇 |
1971年 | 22篇 |
1969年 | 20篇 |
排序方式: 共有6919条查询结果,搜索用时 31 毫秒
141.
Nicole M. Acquisto Heather Lenhardt Benjamin Sensenbach Julie Purick Courtney M. C. Jones 《Prehospital emergency care》2018,22(5):645-649
Objective: To assess the accuracy of multiple Intravenous Infusion Flow Regulators (IIFRs) at infusion rates and hanging heights common to the prehospital setting. Methods: Five different manufacturer's IIFRs were tested over a range of infusion rates while hanging at heights equivalent to the gurney pole, ambulance ceiling hook, and manufacturer's recommended height (if available). Each IIFR was run over a 15-minute period at each infusion rate and height three times. Drip effluent was collected and measured for comparison of volumes. Intra- and inter-device accuracy at different infusion rates and heights was calculated. Results: All devices deviated from the expected infusion volume regardless of infusion rate or height. There was inter-device variability across all IIFRs with some having reproducible though inaccurate volumes. Volumes were consistently below expected at lower heights and above expected at increased heights. Manufacturer recommended height guidelines provided slight improvements in accuracy. Conclusions: Significant deviations from expected IIFR volume were observed across all devices, flow rates, and heights in a static, laboratory environment. These findings would lend caution to the use of IIFRs as they could lead to inaccurate medication dosing (both over- or under-dosing) in the prehospital environment. 相似文献
142.
143.
144.
John R Ingram Gareth A O Thomas John Rhodes John T Green Neil D Hawkes Jill L Swift Emmanuel D Srivastava Brian K Evans Geraint T Williams Robert G Newcombe Edward Courtney Suresh Pillai 《Clinical gastroenterology and hepatology》2005,3(11):1107-1114
BACKGROUND & AIMS: Ulcerative colitis (UC) is largely a disease of nonsmokers in which transdermal nicotine improves the symptoms but often causes adverse events (AEs). Nicotine enemas cause fewer AEs and were used as supplemental treatment for active UC. METHODS: We treated 104 patients with active UC with either 6-mg nicotine enemas or placebo enemas for 6 weeks in a randomized double-blind study. Patients continued their oral therapy, if any, for UC: 68 patients were taking mesalamine, 15 patients were taking prednisolone, and 12 patients were taking thiopurines during the study. Clinical, sigmoidoscopic, and histologic assessments were made at baseline and at the end of the study and symptoms were recorded daily on a diary card. The primary end point was induction of clinical remission and clinical improvement also was measured by the UC disease activity index. After the study, patients then used nicotine enemas daily for 4 weeks and sigmoidoscopy with a biopsy examination was repeated. AEs and salivary cotinine levels were monitored throughout the study. RESULTS: Clinical remission was achieved in 14 of 52 (27%) patients on active treatment and 14 of 43 (33%) patients on placebo (P = .55). The UC disease activity index improved by 1.45 points in the active group and by 1.65 points for those on placebo (P = .88). Only 1 patient discontinued treatment because of an AE (abdominal pain). In the 47 patients taking mesalamine only, active treatment conferred benefit that was not statistically significant; disease remission occurred in 9 of 25 patients on active therapy and 4 of 21 patients on placebo (P = .20). CONCLUSIONS: Six-milligram nicotine enemas were well tolerated but were not found to be efficacious for active UC. 相似文献
145.
Logan G. Spector Jeremiah S. Menk Jessica H. Knight Courtney McCracken Amanda S. Thomas Jeffrey M. Vinocur Matthew E. Oster James D. St Louis James H. Moller Lazaros Kochilas 《Journal of the American College of Cardiology》2018,71(21):2434-2446
Background
Congenital heart surgery has improved the survival of patients with even the most complex defects, but the long-term survival after these procedures has not been fully described.Objectives
The purpose of this study was to evaluate the long-term survival of patients (age <21 years) who were operated on for congenital heart defects (CHDs).Methods
This study used the Pediatric Cardiac Care Consortium data, a U.S.-based, multicenter registry of pediatric cardiac surgery. Survival analysis included 35,998 patients who survived their first congenital heart surgery at <21 years of age and had adequate identifiers for linkage with the National Death Index through 2014. Survival was compared to that in the general population using standardized mortality ratios (SMRs).Results
After a median follow-up of 18 years (645,806 person-years), 3,191 deaths occurred with an overall SMR of 8.3 (95% confidence interval [CI]: 8.0 to 8.7). The 15-year SMR decreased from 12.7 (95% CI: 11.9 to 13.6) in the early era (1982 to 1992) to 10.0 (95% CI: 9.3 to 10.8) in the late era (1998 to 2003). The SMR remained elevated even for mild forms of CHD such as patent ductus arteriosus (SMR 4.5) and atrial septal defects (SMR 4.9). The largest decreases in SMR occurred for patients with transposition of great arteries (early: 11.0 vs. late: 3.8; p < 0.05), complete atrioventricular canal (31.3 vs. 15.3; p < 0.05), and single ventricle (53.7 vs. 31.3; p < 0.05).Conclusions
In this large U.S. cohort, long-term mortality after congenital heart surgery was elevated across all forms of CHD. Survival has improved over time, particularly for severe defects with significant changes in their management strategy, but still lags behind the general population. 相似文献146.
K A Steingold L Laufer R J Chetkowski J D DeFazio D W Matt D R Meldrum H L Judd 《The Journal of clinical endocrinology and metabolism》1985,61(4):627-632
A randomized prospective double blind study was performed to assess the ability of a transdermal therapeutic system (TTS) delivering estradiol (E2) to suppress hot flashes (HFs) in symptomatic postmenopausal women. Patients were given placebo or E2 in four doses for a 20-day period, and serum gonadotropin and estrogen levels and the occurrences of HFs were measured. Administration of placebo had no measurable effect on either estrogen or gonadotropin levels or the occurrence of HFs. A dose-response relationship was found between the rate of E2 administered and the circulating level of E2, with 25, 50, 100, and 200 micrograms/24 h dosages raising the mean E2 concentrations from mean baseline levels of 5-8 pg/ml to 18, 38, 73, and 100 pg/ml, respectively. Estrone levels also increased with TTS application, but to a lesser extent than did E2 levels. Dose-response reductions of FSH and LH with increasing amounts of E2 administration occurred, but gonadotropin levels were not lowered in any of the patients into the ranges found in premenopausal women. TTS application significantly suppressed the occurrence of HFs at the 50 micrograms/24 h dosage and higher. A significant negative correlation (r = 0.6045; P less than 0.001) between E2 levels and the rates of occurrence of HFs was found during hormone administration. Based on this regression, 50% and 100% reductions of HFs should occur at 61 and 122 pg/ml E2. These data indicate that the transdermal delivery of E2 with these systems significantly reduced the occurrence of HFs and allowed definition of the therapeutic range of hormone replacement in terms of lost ovarian function, as reflected by circulating E2 levels. 相似文献
147.
Kraus CL Salazar NC Mitchell JR Florin WD Guenther B Brady D Swartzwelder SH White AM 《Alcoholism, clinical and experimental research》2005,29(9):1672-1676
BACKGROUND: Alcohol use by college students is commonly measured through the use of surveys. The validity of such data hinge on the assumption that students are aware of how much alcohol they actually consume. Recent studies call this assumption into question. Students tend to overestimate the appropriate sizes of standard drinks, suggesting that they might underestimate how much alcohol they consume. If this is true, then students' actual blood alcohol concentrations (BACs) should be higher than BACs estimated based on self-report data. The present study examined this issue METHODS: Breathalyzer readings and self-reported drinking data were collected from 152 college students during the fall of 2004. Estimated BACs were calculated by means of a standard formula, and the relation between actual and estimated BACs was examined. Factors contributing to discrepancies between the two values were identified RESULTS: Estimated BAC levels were significantly higher, not lower, than breath BAC measures. The accuracy of estimated BACs decreased as the number of drinks and amount of time spent drinking increased. Being male and drinking only beer predicted greater accuracy of estimated BACs CONCLUSIONS: Although laboratory data suggest that students underestimate how much they drink, the hypothesis was not supported by data collected in the field. It appears that students might actually overestimate rather than underestimate their levels of consumption when surveyed in the midst of a night of drinking. The findings corroborate observations made by other researchers and suggest that the findings of laboratory studies on college drinking do not necessarily extend to real-world settings. 相似文献
148.
149.