全文获取类型
收费全文 | 2277篇 |
免费 | 163篇 |
国内免费 | 20篇 |
专业分类
耳鼻咽喉 | 12篇 |
儿科学 | 98篇 |
妇产科学 | 29篇 |
基础医学 | 258篇 |
口腔科学 | 59篇 |
临床医学 | 196篇 |
内科学 | 445篇 |
皮肤病学 | 22篇 |
神经病学 | 231篇 |
特种医学 | 194篇 |
外科学 | 344篇 |
综合类 | 42篇 |
预防医学 | 206篇 |
眼科学 | 36篇 |
药学 | 146篇 |
2篇 | |
肿瘤学 | 140篇 |
出版年
2021年 | 27篇 |
2020年 | 23篇 |
2018年 | 30篇 |
2015年 | 21篇 |
2014年 | 40篇 |
2013年 | 59篇 |
2012年 | 86篇 |
2011年 | 91篇 |
2010年 | 48篇 |
2009年 | 59篇 |
2008年 | 79篇 |
2007年 | 86篇 |
2006年 | 86篇 |
2005年 | 82篇 |
2004年 | 68篇 |
2003年 | 63篇 |
2002年 | 73篇 |
2001年 | 43篇 |
2000年 | 69篇 |
1999年 | 54篇 |
1998年 | 53篇 |
1997年 | 35篇 |
1996年 | 47篇 |
1995年 | 44篇 |
1994年 | 35篇 |
1993年 | 38篇 |
1992年 | 45篇 |
1991年 | 35篇 |
1990年 | 56篇 |
1989年 | 68篇 |
1988年 | 47篇 |
1987年 | 74篇 |
1986年 | 57篇 |
1985年 | 69篇 |
1984年 | 48篇 |
1983年 | 38篇 |
1982年 | 25篇 |
1981年 | 22篇 |
1980年 | 29篇 |
1979年 | 27篇 |
1977年 | 27篇 |
1975年 | 18篇 |
1974年 | 20篇 |
1973年 | 20篇 |
1972年 | 29篇 |
1971年 | 31篇 |
1970年 | 26篇 |
1969年 | 23篇 |
1968年 | 20篇 |
1966年 | 19篇 |
排序方式: 共有2460条查询结果,搜索用时 453 毫秒
21.
22.
G W Ellison L W Myers M R Mickey M C Graves W W Tourtellotte K Syndulko M I Holevoet-Howson C D Lerner M V Frane P Pettler-Jennings 《Neurology》1989,39(8):1018-1026
Ninety-eight patients with multiple sclerosis (MS) in the chronic progression phase entered a 3-year clinical trial to determine if azathioprine (AZ) alone or with adrenal cortical steroids stabilizes the course of MS. In group AM, the patients took AZ throughout and methylprednisolone (MP) for the first 36 weeks. Group AP received AZ and placebo instead of MP. Group PP took placebos for both drugs. We adjusted the AZ to maintain the total white blood cell count within 3,000 to 4,000/mm3; we gave the MP in a fixed dose "pulse" and alternate-day regimen. The "intent-to-treat" groups had no statistically significant differences in the rates of progression among the 3 treatments. Subgroup analysis suggests that patients in the AM group who completed treatment exactly according to protocol did statistically significantly better than the placebo recipients using the sum of Standard Neurological Examination scores, slightly better using the quantitative neuro-performance tests, but no better using Mickey's Illness Severity Scores or Kurtzke's Disability Status Scale. Also, the AZ-treated groups had half the relapse rate of the placebo-treated group. Adverse reactions to AZ accounted for most withdrawals. Hematologic and hepatic abnormalities were significantly associated with AZ, but serious non-MS abnormalities were uncommon and were equally distributed among the 3 groups. Addition of MP to the AZ slightly improved the efficacy of the treatment, but also increased the adverse effects. The benefits of AZ with or without steroids did not outweigh the risks, and therefore we do not recommend this treatment for patients with chronic progressive MS. 相似文献
23.
Otoniel Martínez-Maza Dewey J. Moody Ali R. Rezal George W. Ellison Lawrence W. Myers Wallace W. Tourtellotte John L. Fahey 《Journal of clinical immunology》1987,7(2):107-113
Spontaneous immunoglobulin (Ig) secretion by cells from multiple sclerosis (MS) patients (in the progressive phase) treated with monthly pulse doses of cyclophosphamide (CY) (1000–1600 mg/M2) was measured using the protein A plaque assay, to evaluate the effect of CY treatment on B-cell function. Surprisingly, an increase, rather than a decrease, in Ig-secreting cells was seen following CY treatment. CY-treated MS patients averaged 1380±535 spontaneous total (IgM+G+A) Ig plaque-forming cells (PFC) per 1×106 peripheral blood mononuclear cells (MNC), measured at 15–22 days after monthly CY administration, while healthy adults had 280±47 Ig PFC/106 MNC, and MS patients not treated with CY had 300±43 Ig PFC/106 MNC. The observed increase was due to an increase in IgG and IgA PFC. PFC levels remained elevated for 4 weeks following CY treatment, decreasing to control levels by 7–8 weeks post-CY. A small increase in serum IgG level was noted after >12 months of pulse CY therapy; no increase was seen in CSF IgG levels. A preferential decrease in the number of CD4+ T cells was also seen in the CY-treated MS patients. We propose that the observed increase in the number of spontaneous Ig PFC was due to the CY-induced disruption of the CD4+ T cell-mediated control ofin vivo activated B cells. 相似文献
24.
25.
26.
Gansky SA Ellison JA Rudy D Bergert N Letendre MA Nelson L Kavanagh C Walsh MM 《Journal of Athletic Training》2005,40(2):76-87
Context: Athletes in the United States are at high risk for using spit (smokeless) tobacco (ST) and incurring its associated adverse health effects.Objective: To examine whether an athletic trainer-directed ST intervention could decrease initiation and promote cessation of ST use among male collegiate baseball athletes.Design: Stratified, cluster-randomized controlled trial.Setting: Fifty-two California colleges.Patients or Other Participant(s): A total of 883 subjects in 27 intervention colleges and 702 subjects in 25 control colleges participated, as did 48 certified athletic trainers.Intervention(s): For college athletic trainers and associated dental professionals, a 3-hour video conference, and for collegiate athletes, an oral cancer screening with feedback and brief counseling during the preseason health screenings, athletic trainer support for cessation, and a peer-led educational baseball team meeting.Main Outcome Measure(s): The subjects' ST use over 1 year was assessed by self-report. At the end of the study, the certified athletic trainers were mailed a survey assessing their tobacco use and perceptions and behavior related to tobacco control in the athletic environment. We used multivariable logistic regression models for clustered responses (generalized estimating equations) to test the difference between groups in ST-use initiation and cessation and to identify significant overall predictors of noninitiation and cessation of ST use.Results: Of the 1585 athletes recruited, 1248 (78.7%) were followed up at 12 months. In addition, 48 of the 52 athletic trainers (92%) responded to the 1-year follow-up survey. The ST-use initiation (incidence) was 5.1% in intervention colleges and 8.4% in control colleges (generalized estimating equation odds ratio = 0.58, 95% confidence interval = 0.35-0.99). Predictors of ST noninitiation were low lifetime tobacco and monthly alcohol use (odds ratio = 1.98, 95% confidence interval = 1.40- 2.82) and athletic trainers' report that the baseball coach supported ST-use prevention activities (odds ratio = 1.43, 95% confidence interval = 1.11-1.83). Although at 1 year, cessation of ST use was relatively high in both groups (36%), we noted no significant difference between the groups (odd ratio = 0.94, 95% confidence interval = 0.70-1.27).Conclusions: The intervention was significantly effective in preventing incident ST use but did not significantly increase cessation beyond that seen in the control group. The latter finding is inconsistent with previous studies and may be explained by spillover of the intervention to control colleges, other anti-tobacco activity in control colleges, and/or the small sample of dependent ST users enrolled in the study. 相似文献
27.
Jeffrey P. Ellison 《Developmental dynamics》1974,139(2):209-225
A fluorescence method was used for study of the adrenergic cardiac nerves of the cat. Sixteen regions of the heart were examined. The sinoatrial and atrioventricular nodes and the interatrial septum were the most richly innervated regions of the heart. There was little difference between the density of innervation in sections of atrial and ventricular portions of the myocardium. Most of the adrenergic nerves supplying the ventricles were derived from large bundles in the atrioventricular sulcus and were distributed through the subepicardial plexus. Each coronary artery was sparsely innervated in its initial elastic segment, but the vasa vasorum were well innervated. The main trunks of the coronary arteries were surrounded by plexuses composed only of preterminal axons; adrenergic vasomotor terminals were plentiful on the external surface of the muscular media of major and minor myocardial branches. Dense plexuses of adrenergic nerves were seen in both atrioventricular valves. The pulmonary valve was well innervated and contained more adrenergic nerves than the aortic valve. Perivascular plexuses and freely ending adrenergic terminals were observed in the pericardium. Small intensely fluorescent cells were grouped around small blood vessels in the interatrial septum. Most were in the vicinity of the atrioventricular node. It is suggested that these cells, under neural control may secrete catecholamines into the microcirculation of the interatrial septum. They may exert local humoral control over the atrioventricular node or the atrial parasympathetic ganglia. 相似文献
28.
Hart TC; Bowden DW; Bolyard J; Kula K; Hall K; Wright JT 《Human molecular genetics》1997,6(13):2279-2284
Tricho-dento-osseous syndrome (TDO), MIM# 190320, is transmitted as a
highly penetrant autosomal dominant trait that is characterized by variable
clinical expression. The principal clinical features include kinky/curly
hair in infancy, enamel hypoplasia, taurodontism, as well as increased
thickness and density of cranial bones. Possible genetic linkage has been
reported for TDO with the ABO blood group locus, but the gene defect
remains unknown. We have identified four multiplex families (n = 63, 39
affected, 24 unaffected) from North Carolina segregating TDO. We previously
have excluded a major locus for TDO in the ABO region for these families.
Utilizing a genome-wide search strategy, we obtained conclusive evidence
for linkage of the TDO syndrome locus to markers on chromosome 17q21
(D17S791, Z max = 10.54, Theta = 0.00) with no indication of genetic
heterogeneity. Multipoint analysis suggests the TDO locus is located in a 7
cM chromosomal segment flanked by D17S932 and D17S941. This finding
represents the first step towards isolation and cloning of the TDO gene.
Identification of this gene has important implications for understanding
normal and abnormal craniofacial development of hair, teeth and bone.
相似文献
29.
30.