全文获取类型
收费全文 | 11656篇 |
免费 | 684篇 |
国内免费 | 39篇 |
专业分类
耳鼻咽喉 | 147篇 |
儿科学 | 303篇 |
妇产科学 | 275篇 |
基础医学 | 1496篇 |
口腔科学 | 349篇 |
临床医学 | 1052篇 |
内科学 | 2104篇 |
皮肤病学 | 92篇 |
神经病学 | 1398篇 |
特种医学 | 266篇 |
外科学 | 1344篇 |
综合类 | 150篇 |
一般理论 | 27篇 |
预防医学 | 1200篇 |
眼科学 | 331篇 |
药学 | 923篇 |
中国医学 | 28篇 |
肿瘤学 | 894篇 |
出版年
2022年 | 42篇 |
2021年 | 134篇 |
2020年 | 78篇 |
2019年 | 153篇 |
2018年 | 204篇 |
2017年 | 150篇 |
2016年 | 165篇 |
2015年 | 180篇 |
2014年 | 289篇 |
2013年 | 488篇 |
2012年 | 678篇 |
2011年 | 746篇 |
2010年 | 410篇 |
2009年 | 399篇 |
2008年 | 788篇 |
2007年 | 838篇 |
2006年 | 803篇 |
2005年 | 877篇 |
2004年 | 847篇 |
2003年 | 852篇 |
2002年 | 833篇 |
2001年 | 101篇 |
2000年 | 58篇 |
1999年 | 103篇 |
1998年 | 154篇 |
1997年 | 143篇 |
1996年 | 133篇 |
1995年 | 110篇 |
1994年 | 94篇 |
1993年 | 110篇 |
1992年 | 80篇 |
1991年 | 65篇 |
1990年 | 60篇 |
1989年 | 60篇 |
1988年 | 57篇 |
1987年 | 40篇 |
1986年 | 50篇 |
1985年 | 65篇 |
1984年 | 120篇 |
1983年 | 81篇 |
1982年 | 111篇 |
1981年 | 119篇 |
1980年 | 88篇 |
1979年 | 53篇 |
1978年 | 53篇 |
1977年 | 46篇 |
1976年 | 40篇 |
1975年 | 40篇 |
1974年 | 43篇 |
1973年 | 30篇 |
排序方式: 共有10000条查询结果,搜索用时 328 毫秒
991.
Christian Weyer Mark S Fineman Susan Strobel Larry Shen Joann Data Orville G Kolterman Mario F Sylvestri 《American journal of health-system pharmacy》2005,62(8):816-822
PURPOSE: The pharmacokinetics, pharmacodynamics, and safety of pramlintide and various insulin formulations in patients with type 1 diabetes mellitus (DM) when given as separate injections or mixed in the same syringe before injection were studied. METHODS: In two randomized, open-label, placebo-controlled, five-period-crossover studies, patients with type 1 DM received preprandial injections of pramlintide, short-acting insulin, and long-acting insulin administered either by separate injections or after mixing in various combinations. Serum free insulin and plasma glucose concentrations were measured for 10 hours and plasma pramlintide concentrations for 5 hours after injection. RESULTS: Blood samples were collected from a total of 51 patients. All treatments involving mixtures were comparable to separate injections with respect to the area under the concentration-versus-time curve (AUC) and the maximum concentration (Cmax) of serum free insulin. There were some minor differences in the AUC and Cmax of pramlintide. No injection-site reactions or other unexpected adverse events were observed. CONCLUSION: Mixing pramlintide with short- or long-acting insulin in the same syringe before subcutaneous injection did not affect the pharmacodynamics of glucose or the pharmacokinetics of insulin or pramlintide in a clinically significant manner. 相似文献
992.
P. Kevin Rudeen Julia Creighton David B. Bylund Larry J. Petterborg Susan Paredez 《Journal of pineal research》1990,8(2):153-158
The ontogeny of chick pineal serotonin N-acetyltransferase (NAT) activity was investigated in explanted chick pineal glands at 4, 10 and 21 d of age. Nocturnal levels of the enzyme and the response of the enzyme to light exposure were determined in pineal glands maintained in short-term culture at each age. The results indicate that nocturnal NAT activity was increased in the glands from older birds. Nocturnal levels of NAT activity at the time of the initiation of the experiment were threefold greater in glands from 21-d-old birds as compared to that in glands from 4-day-old chicks. The response to light was similar in all three ages examined; light induced a significant decrease in NAT activity within 60 min in explanted glands from 4-d-old chicks and within 180 min in the glands from the 10- and 21-d-old chicks. A paradoxical transient increase in enzyme activity occurred immediately (within 5 min) following light exposure which was significant in the glands from the youngest chicks, and present, but more variable, in the older chicks. These data indicate that the nocturnal enzyme activity is greater in glands from older birds, but that light exposure of explanted glands initiates a transient rise followed by a decrease in NAT activity at all three ages. 相似文献
993.
994.
Characteristics of monoclonal antibodies to denatured Torpedo and to native calf acetylcholine receptors: Species, subunit and region specificity 总被引:18,自引:0,他引:18
Socrates Tzartos Lorene Langeberg Susan Hochschwender Larry W. Swanson Jon Lindstrom 《Journal of neuroimmunology》1986,10(3):235-253
Seventy-five monoclonal antibodies (mAbs) to sodium dodecyl sulfate-denatured Torpedo californica (66 mAbs) and intact fetal calf (9 mAbs) acetylcholine receptor (AChR) were produced. These mAbs were characterized for subunit, region and species specificity, for Ig class and subclass, for protein A binding and for antigen-crosslinking capacity. Fourteen were identified as anti-alpha, 35 were anti-beta, 8 were anti-gamma and 15 were anti-delta. None of the 11 anti-alpha derived from denatured AChR bound to the main immunogenic region (MIR) as judged by antibody competition assays. This contrasts with previous results using mAbs against native AChr, the majority of which bind to the MIR. Thirty-eight mAbs crossreacted with some or all of the tested AChRs from fish electric organs and mammalian muscles in addition to the immunogen. Eight anti-alpha, anti-beta and 1 anti-delta mAbs showed good to excellent autoantibody activity. Analysis by sucrose gradient centrifugation of some AChR-mAb complexes revealed that some mAbs form intermolecular and others form intramolecular crosslinkings of the AChR. The described mAbs have proven valuable tools in AChR and myasthenia gravis research. 相似文献
995.
996.
Androgens regulate bone resorption activity of isolated osteoclasts in vitro 总被引:6,自引:0,他引:6 下载免费PDF全文
Larry Pederson Matthew Kremer Jeffrey Judd David Pascoe Thomas C. Spelsberg B. Lawrence Riggs Merry Jo Oursler 《Proceedings of the National Academy of Sciences of the United States of America》1999,96(2):505-510
For many years it has been recognized that sex steroids have profound effects on bone metabolism. The current perception is that estrogen decreases bone resorption and androgen increases bone deposition. To investigate the potential for androgens to directly modulate bone resorption, we have examined avian osteoclast and human and mouse osteoclast-like cells for androgen responsiveness. There was a dose-dependent decrease in resorption activity in response to α-dihydrotestosterone (α-DHT), β-DHT, testosterone, or the synthetic androgen RU1881. This decrease was blocked by cotreatment with the specific androgen antagonist hydroxyflutamide. Further examination of avian osteoclasts revealed that the cells exhibited specific and saturable nuclear binding of tritiated RU1881 and that α-DHT stimulated the activity of the androgen response element as measured by using a chloramphenicol acetyltransferase reporter plasmid. In addition, avian osteoclasts responded to androgen treatment with elevated production and secretion of transforming growth factor β, a well documented response to androgen exposure in other cell systems. Treatment with either α-DHT or β-DHT for 24 hours resulted in a significant dose-dependent decrease in secretion of cathepsin B and tartrate-resistant acid phosphatase. This response to β-DHT, a stereoisomer of α-DHT that is inactive in other androgen receptor-dependent systems, supports the hypothesis that the osteoclast androgen receptor has unusual ligand-binding properties. Taken together, these results confirm the presence of functional androgen receptors in these cells and support the conclusion that osteoclasts are able to respond directly to androgens in vitro and thus are potential androgen target cells in vivo. 相似文献
997.
998.
Zurab G. Nadareishvili MD PhD Vadim Beletsky MD PhD Sandra E. Black MD Stephen E. Fremes MD Morris Freedman MD David Kurzman PhD Larry Leach PhD John W. Norris MD 《Journal of neuroimaging》2002,12(4):310-315
BACKGROUND AND PURPOSE: High-intensity transient signals (HITS) are frequently detected by transcranial Doppler (TCD) ultrasound in patients with mechanical prosthetic heart valves (PHVs), but published data about their clinical relevance are controversial. This study was undertaken to determine the clinical relevance of HITS in patients with mechanical PHVs. METHODS: The authors prospectively studied patients with mechanical PHVs using TCD monitoring for microemboli detection with and without O2 inhalation. The cognitive testing of patients included the Mini-Mental State Examination, the Dementia Rating Scale, and MicroCog. RESULTS: The authors studied 36 patients (20 women, aged 58 +/- 13 years). HITS were detected in 72% of patients, with a nonsignificant increase of HITS rate in the aortic valve group (P = .07). There was no significant difference in HITS rate between asymptomatic and symptomatic patients. In a multiple linear regression model, HITS rate was predicted only by younger age (P = .024). No correlation was found between HITS rate and the cognitive performance of patients. There was a significant decrease in HITS rate after 100% O2 inhalation compared to baseline levels (32.8 +/- 40.2 vs 6.1 +/- 11.3, P = .011). Subgroup analysis in asymptomatic patients confirmed this finding (P = .017), but in symptomatic patients, decreased HITS rate was not statistically significant (P = .18). CONCLUSION: Only age was a significant predictor of HITS in patients with mechanical PHVs. The lack of association between HITS, clinical symptoms, and cognitive functioning suggests that most of these signals represent harmless epiphenomena, and only HITS detected after O2 inhalation have any clinical relevance. 相似文献
999.
Bactericidal Activity and Postantibiotic Effect of Levofloxacin against Anaerobes 总被引:1,自引:0,他引:1 下载免费PDF全文
Susan L. Pendland Mariela Diaz-Linares Kevin W. Garey Jennifer G. Woodward Seonyoung Ryu Larry H. Danziger 《Antimicrobial agents and chemotherapy》1999,43(10):2547-2549
The bactericidal activity and postantibiotic effect (PAE) of levofloxacin against nine anaerobes were determined. Levofloxacin at concentrations of the MIC and twice the MIC was bactericidal at 24 h to five of nine and nine of nine strains, respectively. The PAE of levofloxacin following a 2-h exposure ranged from 0.06 to 2.88 h. 相似文献
1000.