全文获取类型
收费全文 | 74577篇 |
免费 | 4659篇 |
国内免费 | 270篇 |
专业分类
耳鼻咽喉 | 1132篇 |
儿科学 | 2174篇 |
妇产科学 | 1394篇 |
基础医学 | 8269篇 |
口腔科学 | 1524篇 |
临床医学 | 7418篇 |
内科学 | 15494篇 |
皮肤病学 | 1136篇 |
神经病学 | 7124篇 |
特种医学 | 2614篇 |
外国民族医学 | 5篇 |
外科学 | 12936篇 |
综合类 | 914篇 |
一般理论 | 94篇 |
预防医学 | 6275篇 |
眼科学 | 1417篇 |
药学 | 4769篇 |
中国医学 | 113篇 |
肿瘤学 | 4704篇 |
出版年
2023年 | 401篇 |
2022年 | 665篇 |
2021年 | 1821篇 |
2020年 | 957篇 |
2019年 | 1594篇 |
2018年 | 1864篇 |
2017年 | 1347篇 |
2016年 | 1363篇 |
2015年 | 1519篇 |
2014年 | 2321篇 |
2013年 | 3289篇 |
2012年 | 4982篇 |
2011年 | 5166篇 |
2010年 | 2857篇 |
2009年 | 2510篇 |
2008年 | 4607篇 |
2007年 | 4864篇 |
2006年 | 4724篇 |
2005年 | 4685篇 |
2004年 | 4458篇 |
2003年 | 4106篇 |
2002年 | 3804篇 |
2001年 | 704篇 |
2000年 | 620篇 |
1999年 | 722篇 |
1998年 | 779篇 |
1997年 | 700篇 |
1996年 | 621篇 |
1995年 | 548篇 |
1994年 | 537篇 |
1993年 | 450篇 |
1992年 | 452篇 |
1991年 | 439篇 |
1990年 | 375篇 |
1989年 | 356篇 |
1988年 | 341篇 |
1987年 | 328篇 |
1986年 | 336篇 |
1985年 | 423篇 |
1984年 | 490篇 |
1983年 | 408篇 |
1982年 | 568篇 |
1981年 | 520篇 |
1980年 | 474篇 |
1979年 | 260篇 |
1978年 | 318篇 |
1977年 | 288篇 |
1976年 | 229篇 |
1975年 | 246篇 |
1974年 | 219篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
51.
Lih-Heng Tang Joseph A. Buckwalter Lawrence C. Rosenberg 《Journal of orthopaedic research》1996,14(2):334-339
Previous work has shown that alterations in proteoglycan aggregates are among the first changes detected with aging, disuse, and degeneration of articular cartilage, yet the cause or causes of these alterations remain unknown. To determine if differences in link protein concentration can explain alterations in the assembly, size, and stability of articular cartilage proteoglycan aggregates, we isolated proteoglycan monomer (aggrecan) and link protein from adult bovine articular cartilage and then assembled proteoglycan aggregates from aggrecan and 0.8% hyaluronan relative to aggrecan weight, in the presence of 0, 2, 4, 6, 8, 10, 15, and 20% concentrations of link protein relative to aggrecan weight. We determined the amount, sedimentation coefficient, and stability of the aggregates by analytical ultracentrifugation and measured their dimensions by electron microscopy with use of the monolayer technique. Increased aggregate size, as determined by ultracentrifugation, was directly correlated with an increased number of aggrecans per aggregate and with increased hyaluronan length, as determined by electron microscopy. The concentration of link protein significantly influenced aggregation: concentrations of 6–8% produced maximum aggregation, aggregate stability, and uniformity of aggrecan spacing; concentrations greater than 10% led to the formation of superaggregates (aggregates with sedimentation velocities greater than 100 S that may result from linking two or more hyaluronan filaments) but decreased aggregate stability; and concentrations of less than 4% link protein significantly decreased aggregation, the size and stability of aggregates, and the regularity of aggrecan spacing. The latter observations suggest that a decline in the concentration of link protein could decrease the organization and stability of the articular cartilage matrix. 相似文献
52.
53.
54.
Robin E. Clark Ph.D. Philip W. Bush M.B.A. Deborah R. Becker M.Ed. Robert E. Drake M.D. Ph.D. 《Administration and policy in mental health》1996,24(1):63-77
Recent research suggests that, for some people with severe mental illness, supported employment could improve vocational outcomes for little additional expense. This study describes the costs and client outcomes in one mental health center that converted two rehabilitative day treatment programs to supported employment. Converting from day treatment to supported employment improved vocational outcomes significantly without increasing costs. Although total costs for community treatment were lower in both sites after implementing supported employment, differences appeared to be due to decreasing unit costs over the study period. Results illustrate the importance of testing the effects of cost estimation methods on findings.This study was supported by West Central Services, the New Hampshire Division of Mental Health and Developmental Services, and NIMH grant K02-MH-00839. The authors are grateful to Jesse Turner and Phil Wyzik for facilitating the research. 相似文献
55.
Gideon Fait MD Dan Grisaru MD Michael Shenhav MD Michael J. Kupfermine MD Joseph B. Lessing MD M. Reuben Peyser MD Ariel Jaffa MD 《The Australian & New Zealand journal of obstetrics & gynaecology》1997,37(2):174-176
Summary: One hundred five women with a documented pregnancy of 41 weeks' gestation or more, admitted for induction of labour by balloon catheter with extra-amniotic saline instillation, were retrospectively compared to 196 women admitted in spontaneous labour at the same gestational age, with regard to mode of delivery. The success rate of the induction group was 97.1%. The mode of delivery did not differ significantly between the 2 groups. The Caesarean section rates were 11.4% in the induction group versus 9.7% in the spontaneous group. The mode of delivery after induction of labour by balloon catheter with extra-amniotic saline instillation and simultaneously commenced intravenous oxytocin infusion, in pregnancies of 41 weeks or more, is similar to that of spontaneous deliveries at the same gestational age. 相似文献
56.
57.
Joseph I. Sirven Barbara L. Malamut Joyce D. Liporace Michael J. O'Connor Michael R. Sperling Michael J. O'Connor 《Annals of neurology》1997,42(6):873-878
We determined how noninvasive presurgical data relate to prognosis after temporal lobectomy in patients with independent bilateral temporal lobe (IBTL) complex partial seizures on the intracranial electroencephalogram (EEG). Between 1986 and 1994, 28 patients had IBTL seizures on intracranial EEG. Fifteen of these 28 patients underwent temporal lobectomy and 13 were not offered surgery. Of the 15 patients who had surgery, 10 patients became seizure-free. Magnetic resonance imaging (MRI) and the Wada test were the only variables associated with a seizure-free outcome. Seven of 10 seizure-free patients had a lateralized Wada result or the presence of unilateral hippocampal sclerosis, whereas none of the patients with persistent seizures had either of these findings. Variables not found to be predictive of a seizure-free outcome included location of scalp interictal spikes, degree of seizure-onset laterality, presence of early epilepsy risk factor, duration of epilepsy, and full-scale intelligence quotient. We conclude that MRI and the Wada test provide information of prognostic value in patients with bilateral temporal seizures independent of intracranial EEG data. 相似文献
58.
Serious systemic reactions caused by currently used ionic and nonionic contrast material are the anaphylactoid (allergic-like) reaction and the vagal reaction. Each likely has more than one etiology, and certain patients are at higher risk for developing such a reaction. The urologist and radiologist must be able to differentiate between the clinical manifestations of the anaphylactoid (asthma-like) reaction and the vagal (bradycardia and hypotension) reaction. Specific treatment for the anaphylactoid reaction is low-dose epinephrine; specific treatment for the vagal reaction is intravenous fluid and high-dose atropine. 相似文献
59.
K S Barron A K Joseph M Macleod J C Gonzales D Owerbach J D Reveille 《The Journal of rheumatology》1991,18(11):1723-1729
HLA-DR, DQ, and DP alleles were determined by restriction fragment length polymorphism (RFLP) and oligonucleotide hybridization analysis in 50 Caucasian children with pauciarticular juvenile rheumatoid arthritis (PaJRA) and 82 controls. There was an increased frequency of DR5, DRw8, and DQw4, as well as individual DQ alpha and beta chains, DQA*0401 and DQB1*0402, respectively, in this group of patients. There was an absolute association between DRw8, DQw4, DQA1*0401, and DQB1*0402 in the patient population. HLA-DPw2.1 was also increased in frequency. There was little evidence of linkage disequilibrium found between DPw2.1 and DR5, DRw8, or DQw4. These MHC Class II associations were more characteristic of those patients with young age of onset (less than 5 years), rather than those with onset greater than or equal to 5 years of age. Our data confirmed the previous associations of HLA-DR5, DRw8, and DPw2.1 with PaJRA and suggested a new association for DQ alpha and beta genes in the clinical expression of this disease. 相似文献
60.
Paul D. Gittelman Joseph B. Jacobs Arthur S. Lebowitz Philip M. Tierno 《The Laryngoscope》1991,101(7):733-737
Toxic shock syndrome has been associated with rhinologic surgery and medical devices, and it has been linked to a circulating exotoxin of a toxogenic strain of Staphylococcus aureus. One hundred forty patients with rhinosinusitis were studied. Nasal cultures were obtained. The microbiological characteristics are described. The carrier rate for Staphylococcus aureus was 35%. Thirty percent of patients selected for surgery were Staphylococcus aureus carriers. Toxin-capable isolates were identified in 40% of those tested. Users of cocaine, topical decongestants, and steroid sprays had a statistically higher rate of Staphylococcus aureus carriage compared to non-users. It is hoped that by identifying the population at risk and defining the factors associated with the development of toxic shock syndrome, a cogent policy of prevention can be established. 相似文献