全文获取类型
收费全文 | 845篇 |
免费 | 60篇 |
国内免费 | 23篇 |
专业分类
耳鼻咽喉 | 4篇 |
儿科学 | 38篇 |
妇产科学 | 10篇 |
基础医学 | 105篇 |
口腔科学 | 65篇 |
临床医学 | 84篇 |
内科学 | 198篇 |
皮肤病学 | 18篇 |
神经病学 | 51篇 |
特种医学 | 99篇 |
外科学 | 66篇 |
综合类 | 19篇 |
预防医学 | 45篇 |
眼科学 | 17篇 |
药学 | 65篇 |
中国医学 | 1篇 |
肿瘤学 | 43篇 |
出版年
2021年 | 15篇 |
2020年 | 7篇 |
2019年 | 6篇 |
2018年 | 14篇 |
2017年 | 6篇 |
2015年 | 10篇 |
2014年 | 17篇 |
2013年 | 22篇 |
2012年 | 30篇 |
2011年 | 27篇 |
2010年 | 34篇 |
2009年 | 19篇 |
2008年 | 23篇 |
2007年 | 48篇 |
2006年 | 25篇 |
2005年 | 31篇 |
2004年 | 21篇 |
2003年 | 18篇 |
2002年 | 25篇 |
2001年 | 17篇 |
2000年 | 17篇 |
1999年 | 25篇 |
1998年 | 19篇 |
1997年 | 28篇 |
1996年 | 17篇 |
1995年 | 17篇 |
1994年 | 11篇 |
1993年 | 17篇 |
1992年 | 16篇 |
1991年 | 17篇 |
1990年 | 23篇 |
1989年 | 43篇 |
1988年 | 40篇 |
1987年 | 27篇 |
1986年 | 30篇 |
1985年 | 18篇 |
1984年 | 15篇 |
1983年 | 8篇 |
1982年 | 9篇 |
1981年 | 5篇 |
1980年 | 5篇 |
1979年 | 7篇 |
1978年 | 7篇 |
1977年 | 16篇 |
1976年 | 14篇 |
1974年 | 8篇 |
1973年 | 9篇 |
1972年 | 6篇 |
1969年 | 4篇 |
1968年 | 6篇 |
排序方式: 共有928条查询结果,搜索用时 78 毫秒
61.
Although the introduction of angiotensin-converting enzyme (ACE) inhibitors and β-adrenergic blockers has resulted in significant
improvements in the management of heart failure (HF), morbidity and mortality remain high. Therefore, additional approaches
have been sought to discover newer agents that might add incremental benefit. Although not all of these approaches have been
successful, there have been some notable new approaches to therapy that have shown benefit or may be promising in terms of
additional benefit. Most of these agents are targeted to achieve a more global neurohormonal blockade aiming to reduce or
potentially reverse the ventricular remodeling process that occurs in HF. Some of the newer approaches aim for targets other
than neurohormonal systems, eg, effects on myocardial metabolism or the vasculature. This article reviews the latest advances in pharmacologic therapy in
HF, looking at several trials that may have a significant impact on the treatment of HF. We also discuss several newer agents
with promising potential in HF management. 相似文献
62.
63.
Augmentation index (AI), a measure of enhanced wave reflection, has been proposed as a bedside measure of aortic stiffness. However, because AI is potentially sensitive to various factors other than vessel wall stiffness, the utility of AI as a stiffness indicator may be limited. To assess relations between AI and vascular properties, we used arterial tonometry and aortic Doppler flow to evaluate trough (24 hours) and peak (4 hours) pulsatile hemodynamics and pulse wave velocity in 159 individuals with systolic hypertension at the completion of a 12-week period of monotherapy with the vasopeptidase inhibitor omapatrilat (80 mg; n=75) or the converting enzyme inhibitor enalapril (40 mg; n=84). Characteristic impedance (Zc) was calculated from the ratio of change in carotid pressure and aortic flow in early systole. Systolic ejection period (SEP), timing of wave reflection, and AI were assessed from the carotid waveform. Comparable acute reductions in mean pressure were associated with greater reductions in peripheral resistance with enalapril, whereas neither drug had an acute effect on Zc. Both drugs reduced AI, but neither drug altered the timing of wave reflection. Both drugs increased heart rate and shortened SEP. Multiple regression analysis demonstrated that the acute reduction in AI was most affected by reductions in SEP and peripheral resistance. Change in AI was inversely related to change in Zc and pulse wave velocity did not enter the model. Our findings indicate that AI is a complex surrogate marker that is inversely related to changes in proximal aortic stiffness in systolic hypertension. 相似文献
64.
65.
Binns HJ Gray KA Chen T Finster ME Peneff N Schaefer P Ovsey V Fernandes J Brown M Dunlap B 《Environmental research》2004,96(2):127-138
This study was designed primarily to evaluate the effectiveness of landscape coverings to reduce the potential for exposure to lead-contaminated soil in an urban neighborhood. Residential properties were randomized in to three groups: application of ground coverings/barriers plus placement of a raised garden bed (RB), application of ground coverings/barriers only (no raised bed, NRB), and control. Outcomes evaluated soil lead concentration (employing a weighting method to assess acute hazard soil lead [areas not fully covered] and potential hazard soil lead [all soil surfaces regardless of covering status]), density of landscape coverings (6 = heavy, > 90% covered; 1 = bare, < 10% covered), lead tracked onto carpeted entryway floor mats, and entryway floor dust lead loadings. Over 1 year, the intervention groups had significantly reduced acute hazard soil lead concentration (median change: RB, -478 ppm; NRB, -698 ppm; control, +52 ppm; Kruskal-Wallis, P = 0.02), enhanced landscape coverings (mean change in score: RB, +0.6; NRB, +1.5; control, -0.6; ANOVA, P < 0.001), and a 50% decrease in lead tracked onto the floor mats. The potential hazard soil lead concentration and the entryway floor dust lead loading did not change significantly. Techniques evaluated by this study are feasible for use by property owners but will require continued maintenance. The long-term sustainability of the method needs further examination. 相似文献
66.
Leyden J Bergfeld W Drake L Dunlap F Goldman MP Gottlieb AB Heffernan MP Hickman JG Hordinsky M Jarrett M Kang S Lucky A Peck G Phillips T Rapaport M Roberts J Savin R Sawaya ME Shalita A Shavin J Shaw JC Stein L Stewart D Strauss J Swinehart J Swinyer L Thiboutot D Washenik K Weinstein G Whiting D Pappas F Sanchez M Terranella L Waldstreicher J 《Journal of the American Academy of Dermatology》2004,50(3):443-447
Excessive sebum production is a central aspect of the pathophysiology of acne vulgaris. Sebaceous gland function is under androgen control and it is hypothesized that dihydrotestosterone is formed by the action of 5 alpha-reductase. Type I is the controlling isoenzyme. This study describes a 3-month, multicenter, randomized, placebo-controlled clinical trial with a potent, selective inhibitor of type I 5 alpha-reductase used alone and in combination with systemic minocycline. Inhibition of type I 5 alpha-reductase was not associated with clinical improvement of acne when used alone and did not enhance the clinical benefit of systemic minocycline. These results indicate the need for further work at the molecular level to better understand the action of androgens on sebaceous gland function. 相似文献
67.
Dunlap N Schwartz GG Eads D Cramer SD Sherk AB John V Koumenis C 《British journal of cancer》2003,89(4):746-753
Radiotherapy with external beam radiation or brachytherapy is an established therapeutic modality for prostate cancer. Approximately 30% of patients with localised prostate cancer relapse at the irradiated site. Secondary effects of ionising radiation (IR), for example, bowel and bladder complications, are common. Thus, the search for biological response modifiers that could potentiate the therapeutic effects of radiation and limit the occurrence of serious side effects is an important task in prostate cancer therapy. 1alpha,25-Dihydroxyvitamin D(3) (calcitriol), the active metabolite of vitamin D, and its analogues are under investigation for the treatment of several malignancies including prostate cancer. Here, we report that 1alpha,25-dihydroxyvitamin D(3) and its less calcaemic analogue 19-nor-1alpha,25-(OH)(2)D(2) (Zemplar) act synergistically with IR to inhibit the growth of the human prostate cancer cells in vitro. 1alpha,25-dihydroxyvitamin D(3) potentiated IR-induced apoptosis of LNCaP cells, and nanomolar doses of 1alpha,25-dihydroxyvitamin D(3) and 19-nor-1alpha,25-(OH)(2)D(2) showed synergistic inhibition of growth of LNCaP cells at radiobiologically relevant doses of IR (1-2 Gy). At higher doses of IR, the combination of 1alpha,25-dihydroxyvitamin D(3) and IR or 19-nor-1alpha,25-(OH)(2)D(2) and IR resulted in moderate antagonism. The synergistic effect at radiobiologically relevant doses of radiation suggests that a combination of 1alpha,25-dihydroxyvitamin D(3) or 19-nor-1alpha,25-(OH)(2)D(2) with IR could permit a reduction in the dose of radiation given clinically and thus potentially reduce treatment-related morbidity. 相似文献
68.
Id proteins in cell growth and tumorigenesis 总被引:8,自引:0,他引:8
Since the gene encoding Id1 was cloned in 1990, Id proteins have been implicated in regulating a variety of cellular processes, including cellular growth, senescence, differentiation, apoptosis, angiogenesis, and neoplastic transformation. The development of knockout and transgenic animal models for many members of the Id gene family has been particularly useful in sorting out the biologic relevance of these genes and their expression during normal development, malignant transformation, and tumor progression. Here we review the current understanding of Id gene function, the biologic consequences of Id gene expression, and the implications for Id gene regulation of cell growth and tumorigenesis. 相似文献
69.
Yamamoto Y Maita N Fujisawa A Takashima J Ishii Y Dunlap WC 《Journal of natural products》1999,62(12):1685-1687
A novel alpha-tocomonoenol 3,4-dihydro-2,5,7,8-tetramethyl-2-(4,8,12-trimethyl-12-tridecenyl )-2H-1- benzopyran-6-ol[ having an unusual methylene unsaturation at the isoprenoid-chain terminus of alpha-tocopherol was isolated from the lipophilic fraction of chum salmon eggs. The structure of this marine-derived tocopherol (MDT) was established by spectral analyses. The peroxyl radical-trapping activities of MDT and alpha-tocopherol were compared in aqueous phosphatidylcholine liposomal suspension and in methanolic solution at 37 degrees C. The antioxidant activity of MDT was found to be identical to that of alpha-tocopherol under the experimental conditions of measurement. 相似文献
70.
筛窦癌发病率低,就诊时病期晚,5年无瘤生存率为30%~50%。由于解剖部位的限制以及局部浸润,放射和手术均有一定难度。作者回顾性分析皇家Margret医院1976~1994年收治的29例浸润性筛窦癌根治性放射治疗的疗效和影响预后因素。男性24例,女性4例,中位年龄62岁,中位随访时间4年。常有鼻出血、鼻塞、疼痛及视力改变等。起病到确诊的平均时间为9个月。27例吸烟,10例从事伐木或镍的开采与提炼。 治疗前均经临床及影像学检查。仅3例局限于筛窦,余侵犯鼻腔、蝶窦、眼眶、上颌窦、额窦及脑内等。T1… 相似文献