全文获取类型
收费全文 | 402122篇 |
免费 | 20739篇 |
国内免费 | 849篇 |
专业分类
耳鼻咽喉 | 5187篇 |
儿科学 | 12524篇 |
妇产科学 | 8421篇 |
基础医学 | 56680篇 |
口腔科学 | 12775篇 |
临床医学 | 31121篇 |
内科学 | 88583篇 |
皮肤病学 | 10443篇 |
神经病学 | 34979篇 |
特种医学 | 12334篇 |
外国民族医学 | 125篇 |
外科学 | 49597篇 |
综合类 | 2398篇 |
现状与发展 | 1篇 |
一般理论 | 131篇 |
预防医学 | 39109篇 |
眼科学 | 7783篇 |
药学 | 27040篇 |
中国医学 | 1387篇 |
肿瘤学 | 23092篇 |
出版年
2023年 | 2076篇 |
2022年 | 2824篇 |
2021年 | 7118篇 |
2020年 | 4491篇 |
2019年 | 7320篇 |
2018年 | 11979篇 |
2017年 | 8351篇 |
2016年 | 8162篇 |
2015年 | 9277篇 |
2014年 | 11042篇 |
2013年 | 15958篇 |
2012年 | 26220篇 |
2011年 | 26600篇 |
2010年 | 13448篇 |
2009年 | 11030篇 |
2008年 | 22001篇 |
2007年 | 23535篇 |
2006年 | 21762篇 |
2005年 | 22039篇 |
2004年 | 20694篇 |
2003年 | 18986篇 |
2002年 | 16572篇 |
2001年 | 11075篇 |
2000年 | 11184篇 |
1999年 | 9888篇 |
1998年 | 2479篇 |
1997年 | 2046篇 |
1996年 | 2008篇 |
1995年 | 1758篇 |
1994年 | 1661篇 |
1993年 | 1507篇 |
1992年 | 5916篇 |
1991年 | 5467篇 |
1990年 | 5089篇 |
1989年 | 4830篇 |
1988年 | 4501篇 |
1987年 | 4127篇 |
1986年 | 3931篇 |
1985年 | 3625篇 |
1984年 | 2667篇 |
1983年 | 2211篇 |
1979年 | 2137篇 |
1978年 | 1453篇 |
1975年 | 1352篇 |
1974年 | 1553篇 |
1973年 | 1537篇 |
1972年 | 1388篇 |
1971年 | 1344篇 |
1970年 | 1347篇 |
1969年 | 1367篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
61.
62.
63.
Mortality prognostic factors in chest injury 总被引:2,自引:0,他引:2
1,026 multiple trauma patients (P) were compared to P with chest injuries (PCT) (407). Severity indices were related to type of thoracic injury and mortality. The Injury Severity Score (ISS), Glasgow Coma Scale (GCS), Trauma Score (TS), CHOP, and the Respiratory Index (RI) were used. The mortality rate of P was 27.1% but increased to 32.9% for PCT (p less than 0.05). We noted that mortality rate was highly dependent on major chest trauma: 68.6% for flail chest (FC), 56% for lung contusion (LC), 42.3% for hemothorax (HA), and 38.1% for pneumothorax (PN). ISS and RI scores for PCT survivors were greater than ISS + RI scores for P survivors (p less than 0.05 and p less than 0.01). ISS values for LC, HA, and PN PCT survivors were greater than the ISS of P survivors (p less than 0.01). Nonsurviving PCTs, especially those with lung contusion, showed a highly significant increase in ISS and RI scores. 相似文献
64.
Uptake of Adriamycin in tumour and surrounding brain tissue in patients with malignant gliomas 总被引:1,自引:0,他引:1
H. von Holst E. Knochenhauer H. Blomgren V. P. Collins L. Ehn M. Lindquist G. Norén C. Peterson 《Acta neurochirurgica》1990,104(1-2):13-16
Summary Eight patients with malignant gliomas verified on CT scan, received an intravenous injection of 50 mg of Adriamycin R, 24 hours prior to surgical removal of the tumour. Peroperatively, both tumour and surrounding tissue specimens were obtained for determination of the tissue concentrations of Adriamycin and its reduced metabolite Adriamycinol. It was found that Adriamycin could be detected in tumour tissue from all patients. The concentration varied between 0,9 and 4,6 nmol/g tissue. In contrast, Adriamycin could only be detected in surrounding brain tissue from one patient.In anin vitro study a human malignant glioma cell line (U-251 MG) was exposed to various concentrations of Adriamycin for 24 hours. It was found that an intracellular drug concentration above 30 nmol/g cells caused a concentration dependent inhibition of cell growth. Thus, it is likely that the poor effect of Adriamycin on patients with malignant gliomas is due to an ineffective drug accumulation in the tumour tissue. 相似文献
65.
A L Dannenberg T R Coté M J Kresnow J J Sacks C M Lipsitz E R Schmidt 《Public health reports (Washington, D.C. : 1974)》1993,108(2):212-217
Most of the nearly 1,000 fatal bicycle-related injuries annually could be prevented if riders used safety helmets. Helmet use by adult bicyclists has received relatively little attention because educational campaigns to promote helmet use generally focus on children. Helmet use by adult and child bicyclists at 120 suburban and rural sites in three Maryland counties was observed on two Saturdays in 1990-91 during an evaluation of the impact of a mandatory helmet law. Concordance or discordance of helmet use within various groups of bicyclists--adults only, adults with children, and children only--was recorded. Helmet use among 2,068 adult bicyclists was 49 percent, 51 percent, and 74 percent in the three counties. In two counties combined, 52 percent (365 of 706) of solo adult bicyclists wore helmets compared with only 5 percent (5 of 94) of solo child bicyclists (P < .001). Helmet use or nonuse was concordant among 87 percent of 277 adult-adult pairs, 94 percent of 50 child-child pairs, and 91 percent of 32 adult-child pairs of bicyclists observed. Concordance rates of helmet use or nonuse were similarly high among pairs of adult bicyclists of the same or mixed sexes. These data are consistent with the concept that both adults and children tend to adopt the helmet-wearing behaviors of their companions. Public health efforts focused on adults should encourage helmet use by adult bicyclists both to prevent head injuries and to provide a role model for children. 相似文献
66.
J. de Pedro-Cuesta V. Abraira G.-X. Jiang G. Solders S. Fredrikson 《Acta neurologica Scandinavica》1996,93(2-3):175-183
Using hierarchical cluster analysis, applied to 47 cases of Guillain-Barre Syndrome (GBS) incident in South-West Stockholm (SWS) during the period from January 1973 to June 1992, we identified three major clinicoepidemiological subgroups. The first subgroup, 25.5% of the cases (26.7 ± 6.7 years), recorded a peak incidence at ages 20–29 years and presented significant differences from other subgroups, a high proportion of cases with onset at low age preceded by respiratory infection (83.3%) and with normal motor conduction velocity (50.0%). Also found, were less affected biological parameters, a rapidly progressive course and independence in gait at one month after onset. A second subgroup, 27.7% of cases, was severely affected, clinically and functionally. It consisted predominantly of young individuals (22.7 ± 11.1 years), with a high incidence (69.2% of cases) in autumn. A third subgroup, comprising 40.47; of cases, was older (61.1 ± 11.0 years) and, in general, also severely affected. The incidence of this form appeared to be invariant with time. 相似文献
67.
A Espinosa de los Monteros G Roussel N M Neskovic J L Nussbaum 《Journal of neuroscience research》1988,19(2):202-211
A new chemically defined medium consisting of equal parts of Dulbecco modified Eagle's and Ham's F-12 media supplemented with insulin, sodium selenite, putrescine, and D+ galactose, which allows the long-term survival of mature oligodendrocyte pure cultures, is described. Immunohistochemical staining has shown that over 90% of the cells become positive for myelin proteins shortly following subculture. Contaminating astrocytes (2%) do not survive in this medium. Biochemical data have indicated that these purified oligodendrocytes express 2'3'-cyclic nucleotide 3'-phosphohydrolase and UDP-galactose ceramide galactosyltransferase activities. Electron microscopical examination revealed that the oligodendrocytes were mostly of medium-dark type and appeared to be identical to cells cultured in serum-containing medium. The ability to maintain pure oligodendrocyte cultures in such a defined medium will allow investigations concerning exogenous and endogenous factors involved in oligodendrocyte metabolism. 相似文献
68.
69.
Severe herpetic keratitis. I: Prevalence of visual impairment in a clinic population. 总被引:1,自引:1,他引:0 下载免费PDF全文
We report a prevalence study of the best visual acuity in the affected eye of 100 selected patients with herpetic keratitis seen during a two-year period. Sixty-two patients retained an acuity of 6/9 or better without requiring penetrating keratoplasty (PK). The prevalence of reduced visual acuity severe enough to warrant PK was 33%. Patients requiring PK for whom full clinical records were available suffered a mean of 6.8 episodes of keratitis. In this group of patients the vision of 18 fell from 6/6 to 6/60 over a mean period of 8.5 years. Once visual acuity was permanently reduced to 6/12, 78% of patients proceeded to lose vision to 6/60. Unilateral visual impairment occurs in at least a third of patients with severe herpetic keratitis. Once vision falls permanently to 6/12, the long-term prognosis for vision appears to be poor. 相似文献
70.