全文获取类型
收费全文 | 1599篇 |
免费 | 118篇 |
国内免费 | 1篇 |
专业分类
耳鼻咽喉 | 7篇 |
儿科学 | 92篇 |
妇产科学 | 12篇 |
基础医学 | 298篇 |
口腔科学 | 11篇 |
临床医学 | 108篇 |
内科学 | 325篇 |
皮肤病学 | 23篇 |
神经病学 | 119篇 |
特种医学 | 45篇 |
外科学 | 164篇 |
综合类 | 107篇 |
预防医学 | 153篇 |
眼科学 | 17篇 |
药学 | 97篇 |
中国医学 | 10篇 |
肿瘤学 | 130篇 |
出版年
2023年 | 11篇 |
2022年 | 26篇 |
2021年 | 68篇 |
2020年 | 25篇 |
2019年 | 30篇 |
2018年 | 37篇 |
2017年 | 32篇 |
2016年 | 29篇 |
2015年 | 42篇 |
2014年 | 55篇 |
2013年 | 74篇 |
2012年 | 145篇 |
2011年 | 109篇 |
2010年 | 67篇 |
2009年 | 51篇 |
2008年 | 72篇 |
2007年 | 87篇 |
2006年 | 101篇 |
2005年 | 100篇 |
2004年 | 82篇 |
2003年 | 70篇 |
2002年 | 67篇 |
2001年 | 40篇 |
2000年 | 33篇 |
1999年 | 37篇 |
1998年 | 24篇 |
1997年 | 16篇 |
1996年 | 15篇 |
1995年 | 8篇 |
1994年 | 11篇 |
1993年 | 11篇 |
1992年 | 22篇 |
1991年 | 9篇 |
1990年 | 11篇 |
1989年 | 10篇 |
1988年 | 7篇 |
1987年 | 8篇 |
1986年 | 6篇 |
1985年 | 9篇 |
1984年 | 10篇 |
1983年 | 11篇 |
1982年 | 2篇 |
1981年 | 8篇 |
1976年 | 2篇 |
1975年 | 5篇 |
1974年 | 3篇 |
1972年 | 3篇 |
1971年 | 2篇 |
1969年 | 5篇 |
1965年 | 2篇 |
排序方式: 共有1718条查询结果,搜索用时 156 毫秒
971.
Ehrlich PF Helmkamp JC Williams JM Haque A Furbee PM 《Injury control and safety promotion》2004,11(1):23-28
The purpose of this study was to compare parents' and children's attitudes and habits towards use of bicycle helmets and car seat belts. We hypothesized that parental perception of their children's safety practices did not reflect actual behavior and further, that parental practices, rather than their beliefs about a particular safety practice, have a greater affect on their child's risk-taking behavior. The study population consisted of children in grades four and five and their parents/guardians. Participation in the cross-sectional study was voluntary and confidential anonymous questionnaires were used. In separate and independent surveys, children and parents were questioned in parallel about their knowledge, habits and attitudes toward bicycle helmet use and car safety practices. In the study, 731 students participated with 329 matched child-parent pairs. Ninety-five percent of the children own bicycles and 88% have helmets. Seventy percent of parents report their child always wears a helmet, while only 51% of children report always wearing one (p < 0.05). One-fifth of the children never wear a helmet, whereas parents think only 4% of their children never use one (p < 0.05). Parents report their children wear seat belts 92% of the time while 30% of children report not wearing one. Thirty-eight percent of children ride bicycles with their parents and wear their helmets more often than those who do not ride with their parents (p < 0.05). Parents who always wear a seat belt are more likely to have children who sit in the back seat and wear a seat belt (p < 0.05). Parents' perceptions of their children's safety practices may not be accurate and their actions do affect their children's. Injury prevention programs that target both parents and children may have a greater impact on reducing risk-taking behaviors than working with each group in isolation. 相似文献
972.
In moderately hard Lake Ontario water (approximately 140 mg L(-1) as CaCO3) waterborne Ni (9.7-10.7 mg Ni L(-1)) is acutely toxic to adult rainbow trout (Oncorhynchus mykiss) exclusively via branchial mechanisms. Ventilation in resting trout (evaluated using a ventilatory masking technique) was adversely affected, as ventilation rate (VR), ventilation volume (VG), opercular stroke volume (VSV) and resting oxygen consumption (MO2) were all increased, and oxygen extraction efficiency (U%) decreased over 48 h of Ni exposure. Extensive gill Ni accumulation (41-fold over control levels) during 82 h of waterborne Ni exposure resulted in marked ultrastructural damage to the respiratory epithelium of the gill, including swelling of the secondary lamellae evidenced by changes to both the lamellar region (increased secondary lamellar tissue volume (VSL/V(LR), and to the secondary lamellae themselves (increased volume of tissue lying outside the pillar system (VOPS/VSL). Additionally, decreased lamellar height and increased lamellar width indicated a reduction in lamellar surface area available for gas diffusion. The relative diffusing capacity of experimental fish was only 59% of that of control fish. Infusion of Ni into the blood, achieving a similar time course and magnitude of plasma [Ni] elevation to that during waterborne exposure, failed to elicit any signs of respiratory toxicity typically diagnostic of acute, high level waterborne Ni exposure. Infusion of Ni into the blood for 96 h resulted in only minor accumulation of Ni in the gill, suggesting that acute Ni-induced respiratory toxicity is related to accumulation of high levels of Ni in the gill from the water. Additionally, infusion of Ni into the bloodstream led to significant extrabranchial Ni accumulation only in the kidney. White muscle, heart, liver, stomach, and intestine did not significantly accumulate Ni following infusion into the bloodstream and trapped plasma analysis revealed that, with the exception of the kidney, a substantial portion of Ni accumulated in tissues following infusion could be accounted for by extracellular (blood-bound) Ni. 相似文献
973.
Davis Garrett K Cohen RA Paul RH Moser DJ Malloy PF Shah P Haque O 《The Clinical neuropsychologist》2004,18(1):50-62
White matter hyperintensities (WMHs) are frequently found on MRI studies of vascular dementia (VaD) patients. As several studies have demonstrated that WMHs are often associated with severity of illness, cognitive impairment, and functional decline, the accurate and reliable measurement of WMHs on MRI is an important, yet often overlooked, prerequisite for accurate interpretation of neuroimaging studies. Using a sample of 39 VaD patients, we evaluated the reliability and validity of a visual ordinal rating scale and a computer-mediated thresholding technique to evaluate WMHs. Results indicated the computer-mediated technique had slightly stronger inter-rater reliability than the visual ordinal rating scale. Furthermore, the computer-mediated thresholding technique was correlated with measures of neuropsychological functioning believed to be compromised in VaD (i.e., psychomotor speed, executive functioning) while the visual rating scale was not. Results suggest that this computer-mediated thresholding technique is superior to visual ratings of WMHs. 相似文献
974.
Morikawa S Inubushi T Kurumi Y Naka S Sato K Demura K Tani T Haque HA 《Cardiovascular and interventional radiology》2004,27(4):370-373
We obtained clear and reproducible MR fluoroscopic images and temperature maps for MR image-guided microwave ablation of liver tumors under general anesthesia without suspending the artificial ventilation. Respiratory information was directly obtained from air-way pressure without a sensor on the chest wall. The trigger signal started scanning of one whole image with a spoiled gradient echo sequence. The delay time before the start of scanning was adjusted to acquire the data corresponding to the k-space center at the maximal expiratory phase. The triggered images were apparently clearer than the nontriggered ones and the location of the liver was consistent, which made targeting of the tumor easy. MR temperature images, which were highly susceptible to the movement of the liver, during microwave ablation using a proton resonance frequency method, could be obtained without suspending the artificial ventilation. Respiratory triggering technique was found to be useful for MR fluoroscopic images and MR temperature monitoring in MR-guided microwave ablation of liver tumors under general anesthesia. 相似文献
975.
976.
An association between weight loss and Alzheimer's disease has been established in the general population but little information is available regarding this association in people with intellectual disabilities. A 4-year longitudinal study of adults with Down syndrome with and without Alzheimer's disease was undertaken. Age-associated weight loss was seen in virtually all older adults with Down syndrome. A significant association between weight loss and Alzheimer's disease was found for older adults with Down syndrome. This study highlights important research and clinical issues regarding weight loss and nutrition in Down syndrome adults with dementia. 相似文献
977.
978.
Gross and microscopic ocular findings were prospectively studied in 38 human immunodeficiency virus (HIV)-seropositive subjects
undergoing postmortem examination. Pathologic lesions were detected in 27 patients (71%), with 67% of the abnormal findings
detected only microscopically.
The authors have stated that they do not have a significant financial interest or other relationship with any product manufacturer
or provider of services discussed in this article. 相似文献
979.
Racial and ethnic differences in survival of children with acute lymphoblastic leukemia 总被引:6,自引:2,他引:4
Black children with acute lymphoblastic leukemia (ALL) have poor outcomes, but limited information is available for children from other racial and ethnic backgrounds, such as Hispanic and Asian. We undertook a retrospective cohort study of children with ALL treated on Children's Cancer Group therapeutic protocols to determine outcomes by racial and ethnic backgrounds of patients treated with contemporary risk-based therapy. In total, 8447 children (white, n = 6703; Hispanic, n = 1071; black, n = 506; and Asian, n = 167) with newly diagnosed ALL between 1983 and 1995 were observed for a median of 6.5 years. Analysis of disease outcome was measured as overall survival (OS) and event-free survival (EFS) and was adjusted for known predictors of outcome including clinical features, disease biology, socioeconomic status, and treatment era (1983-1989 vs 1989-1995). There was a statistically significant difference in survival by ethnicity (P <.001). Five-year EFS rates were: Asian, 75.1% +/- 3.5%; white, 72.8% +/- 0.6%; Hispanic, 65.9% +/- 1.5%; and black, 61.5% +/- 2.2%. Multivariate analysis revealed that when compared with white children, black and Hispanic children had worse outcomes and Asian children had better outcomes after adjusting for known risk factors. The poorer outcomes among black children were most apparent among patients with standard-risk features (relative risk [RR], 2.0; 95% confidence interval [CI], 1.6-2.5), whereas poorer outcomes in Hispanic children (RR, 1.4; 95% CI, 1.2-1.6) were most evident among patients with high-risk features. Asian children had better outcomes than all racial and ethnic groups among high-risk patients, particularly in the recent era (5-year EFS, 90.9% +/- 6.1%). Racial and ethnic differences in OS and EFS persist among children with ALL who receive contemporary risk-based therapy. Future studies should focus on reasons-perhaps compliance or pharmacogenetics-for those differences. 相似文献
980.
Abnormalities of chromosome bands 15q13-15 in childhood acute lymphoblastic leukemia 总被引:2,自引:0,他引:2
Heerema NA Sather HN Sensel MG La MK Hutchinson RJ Nachman JB Reaman GH Lange BJ Steinherz PG Bostrom BC Gaynon PS Uckun FM 《Cancer》2002,94(4):1102-1110
BACKGROUND: Recurring breakpoints in chromosome bands 15q13-15 occur infrequently in leukemia. To the authors' knowledge, the clinical significance of these breakpoints in childhood acute lymphoblastic leukemia (ALL) has not been previously investigated. METHODS: Centrally reviewed karyotypes of children with newly diagnosed ALL enrolled on Children's Cancer Group protocols from 1988 to 1995 formed the basis of the current report. Statistical analyses used chi-square tests for homogeneity of proportions, and outcome was analyzed using life table methods and associated statistics. RESULTS: Of 1946 cases with centrally reviewed and accepted cytogenetic analyses, 23 cases (1%) had breakpoints in chromosome bands 15q13-15. Most patients with 15q13-15 breakpoints had standard risk ALL, although breakpoints in 15q13-15 occurred more frequently in infants than in older children. The majority of these patients (16 patients; 70%) had balanced 15q13-15 rearrangements. Additional chromosomal abnormalities not involving 15q included abnormal 12p, abnormal 9p, Philadelphia chromosome, deletion 6q, and an 11q23 breakpoint. Thirteen (57%) 15q13-15 breakpoints occurred in pseudodiploid karyotypes; five (22%) were in hyperdiploid karyotypes with 47-50 chromosomes; two (9%) were in hyperdiploid karyotypes with > 50 chromosomes; and three (13%) were in hypodiploid karyotypes. Of the 23 patients with 15q13-15 breakpoints, 21 were survivors, 18 survived event-free for 2.2-9.3 years, and 3 were alive 1 to 3 years after a relapse at time of writing. CONCLUSIONS: The current study suggests that genes at 15q13-15 may be involved in the leukemogenesis of some cases of childhood ALL, but that with current intensive therapy such aberrations do not confer increased risk of treatment failure. 相似文献