全文获取类型
收费全文 | 2919篇 |
免费 | 146篇 |
国内免费 | 11篇 |
专业分类
耳鼻咽喉 | 29篇 |
儿科学 | 55篇 |
妇产科学 | 41篇 |
基础医学 | 504篇 |
口腔科学 | 115篇 |
临床医学 | 253篇 |
内科学 | 532篇 |
皮肤病学 | 15篇 |
神经病学 | 309篇 |
特种医学 | 143篇 |
外科学 | 517篇 |
综合类 | 29篇 |
预防医学 | 78篇 |
眼科学 | 23篇 |
药学 | 147篇 |
中国医学 | 3篇 |
肿瘤学 | 283篇 |
出版年
2023年 | 7篇 |
2022年 | 20篇 |
2021年 | 62篇 |
2020年 | 28篇 |
2019年 | 39篇 |
2018年 | 48篇 |
2017年 | 31篇 |
2016年 | 66篇 |
2015年 | 91篇 |
2014年 | 86篇 |
2013年 | 115篇 |
2012年 | 180篇 |
2011年 | 208篇 |
2010年 | 96篇 |
2009年 | 130篇 |
2008年 | 179篇 |
2007年 | 229篇 |
2006年 | 204篇 |
2005年 | 210篇 |
2004年 | 201篇 |
2003年 | 204篇 |
2002年 | 202篇 |
2001年 | 48篇 |
2000年 | 24篇 |
1999年 | 30篇 |
1998年 | 40篇 |
1997年 | 37篇 |
1996年 | 26篇 |
1995年 | 25篇 |
1994年 | 23篇 |
1993年 | 13篇 |
1992年 | 14篇 |
1991年 | 23篇 |
1990年 | 23篇 |
1989年 | 13篇 |
1988年 | 11篇 |
1987年 | 5篇 |
1986年 | 5篇 |
1985年 | 5篇 |
1984年 | 5篇 |
1983年 | 4篇 |
1982年 | 11篇 |
1981年 | 10篇 |
1977年 | 4篇 |
1976年 | 3篇 |
1975年 | 3篇 |
1974年 | 3篇 |
1973年 | 5篇 |
1971年 | 4篇 |
1964年 | 4篇 |
排序方式: 共有3076条查询结果,搜索用时 31 毫秒
51.
52.
BACKGROUND AND PURPOSE: In 1990 the skin source measuring bridge was proposed as a tool to measure (1) the distance between the interstitial implant and the overlying skin during brachytherapy boost treatment as well as (2) the distances between the lateral source end and the exit point of the guide needle. The present study reports on the clinical experience using the source skin measuring bridge with respect to incidence and grade of teleangiectasia, and their relation to source skin distances and doses. PATIENTS AND METHODS: Two hundred and twenty-two breast cancer patients (229 breasts) treated between 1983 and 1996 with breast conserving therapy including a brachytherapy boost were scored on the occurrence of teleangiectasia. The minimum distance between the sources (above implant and laterally) and the skin surface were measured. RESULTS: If no bridge was used the appearance of teleangiectasia in the epiderm above the implant is 77, 63 and 50% for boost doses of 25, 20 and 15 Gy, respectively. For brachytherapy boost doses of 25 and 20 Gy and distances smaller than 10mm between the implant and the overlying epiderm, as determined with the skin source measuring bridge, the appearance of teleangiectasia was 78 and 46%, respectively. When respecting provisional dosimetry to spare the skin for a boost dose of 15 Gy, resulting in distances between 10 and 15 mm for the implant overlying skin and distances between 5 and 10 mm for the lateral skin, teleangiectasia can be reduced to a minimum (6.3% above and 3.3% laterally). While in a univariate analysis several parameters (use of the bridge, boost dose, boost modality, external beam therapy modality) were predictive factors, the use of the bridge remained the only significant variable in a multivariate analysis. CONCLUSIONS: The skin source measuring bridge reduces teleangiectasia after interstitial brachytherapy boost treatment. A hypothesis made previously relating teleangiectasia and source skin distances was verified and extended. Even when 3D planning is used, the bridge allows for a provisional calculation of the security margins between source positions and the skin at the time of BT implantation to assure a correct needle positioning from the beginning, instead of correcting dwell times later on to avoid unnecessary high skin doses. 相似文献
53.
Four therapists' participation in six therapies were analyzed at the utterance level. Therapist's utterances (N= 5,504) were rated on 39 categories of the Stuttgart Interactional Category System in two early, two middle, and two late sessions, providing a primary and a cross-validation sample. Application of the P-technique revealed four stable and reliable therapist participatory factors (i.e., Objective Information Exchange Seeking, Directing Insightful/Painful Work, Self-Involving Disclosure, and Advice Giving Information), accounting for 39% of the total variance. Multivariate analyses revealed a significant therapist by phase interaction on all factors, with most differences occurring on the work and disclosure factors in the middle phase and between two groups of therapists (within treatments). Further examination using chronographic analyses revealed (1) some shortcomings in the analysis of variance approach, and (2) significant strengths in identifying naturally occurring episodes of therapist participation. Results are discussed in terms of the need to further develop the use of the P-technique to discover generalizable structures of therapist participation and to track quantitative variations in such structures using chronographic analysis. 相似文献
54.
55.
Vision is the most important sense for humans and it is irreversibly impaired by axonal damage of retinal ganglion cells (RGCs) in the optic nerve due to the lack of axonal regeneration. The failure of regeneration is partially attributable to factors located in the inhibitory environment of the forming glial scar and myelin as well as an insufficient intrinsic ability for axonal regrowth. Moreover, RGCs undergo apoptotic cell death after optic nerve injury, eliminating any chance for regeneration. In this review, we discuss the different aspects that cause regenerative failure in the optic nerve. Moreover, we describe discoveries of the last two decades demonstrating that under certain circumstances mature RGCs can be transformed into an active regenerative state allowing these neurons to survive axotomy and to regenerate axons in the injured optic nerve. In this context we focus on the role of the cytokines ciliary neutrophic factor (CNTF) and leukemia inhibitory factor (LIF), their receptors and the downstream signaling pathways. Furthermore, we discuss strategies to overcome inhibitory signaling induced by molecules associated with optic nerve myelin and the glial scar as well as the regenerative outcome after combinatorial treatments. These findings are encouraging and may open the possibility that clinically meaningful regeneration may become achievable one day in the future. 相似文献
56.
57.
58.
Hans Henkes Hermann Monstadt Klaus U. Wentz Frank Czerwinski Elisabeth Berg-Dammer Dietmar Kühne 《Neurological research》2013,35(3):256-258
AbstractThe aim of the investigation was the technical realization and approval of a new method for insertion and detachment of platinum alloy microcoils and other vascular implants via standard microcatheters. Flexible lightconducting fibers, 105 μm in diameter were connected to platinum alloy microcoils. It was examined whether an insertion wire, a lightconducting fiber and a platinum alloy microcoil could be advanced through a Tracker-18 (Target) microcatheter. The detachment of the attached coil from the lightconducting fiber was investigated. Platinum alloy microcoils can be attached to available lightconducting fibers in a reliable and reproduceable manner. Together with the fiber they can be advanced via a Tracker-18 microcatheter. Only extremely tortuous vessels may increase the friction to critical values. A Ho-YAG laser source was used. This allowed the instantaneous detachment of microcoils from laser fibers. In contrast to electrolytical detachment; no foreign substances are released to the blood stream. The detachment does not require waiting time and does not activate thrombus formation. Due to specific technical features, injuries of the vessel wall are avoided. After further miniaturization and adaption of the lightconducting fibers to the required characteristics; I aster detachment may have the potential to replace current methods such as electrolytical and mechanical coil detachment. [Neurol Res 1996; 18: 256–258] 相似文献
59.
Background
Dipterinyl calcium pentahydrate (DCP) has previously been shown to inhibit MDA-MB-231 human breast cancer xenographs in nude mice in a manner correlated with increases in plasma IL-12 and IL-4 concentrations, and decreases in plasma IL-6 levels. DCP also inhibits indoleamine 2,3-dioxygenase (IDO), an immuno-inhibitory enzyme, in human PBMCs (Peripheral Blood Mononuclear Cells). 相似文献60.
OBJECTIVES: To determine granulocyte colony-stimulating factor (G-CSF), epithelial neutrophil-activating peptide (ENA)-78, and interleukin (IL)-8 in BAL fluid (BALF), epithelial lining fluid (ELF), and serum for establishing the concentration gradient of G-CSF, ENA-78, and IL-8 between the blood and the alveolar space in ARDS and acute lung injury (ALI); and to evaluate the relationship of G-CSF, IL-8, and ENA-78 to pulmonary neutrophilia and severity of lung injury. DESIGN: Prospective study. SETTING: An adult trauma/surgical ICU. PATIENTS: Nineteen patients with ARDS and 10 patients with ALI. INTERVENTIONS: None. Measurements and main results: BAL and blood sampling simultaneously within 12 h and 24 h after onset of ARDS/ALI; G-CSF was detected in BALF in 18 of 19 patients with ARDS, in 7 of 10 patients with ALI, and in all serum samples. G-CSF in BALF and serum was significantly higher in ARDS than in ALI. ENA-78 was detected in BALF in 14 of 19 patients with ARDS, in 8 of 10 patients with ALI, and in serum of all patients. Levels in BALF and serum were not different between ARDS and ALI. IL-8 was detected in all patients; concentrations in BALF in ARDS were significantly higher than in ALI. Concentrations of G-CSF, ENA-78, and IL-8 in ELF were significantly higher than in serum. G-CSF in BALF and serum and IL-8 in BALF correlated positively with pulmonary neutrophilia. G-CSF in serum and IL-8 in BALF correlated negatively with PaO(2)/fraction of inspired oxygen (FIO(2)) ratio. However, ENA-78 did not show a correlation with neutrophil count or with PaO(2)/FIO(2) ratio. CONCLUSIONS: G-CSF may be pathophysiologically important for accumulation and activation of neutrophils in ARDS. Local G-CSF production is the likely driving force for neutrophils rather than elevation of circulating levels. In comparison to ENA-78, IL-8 seems to be the predominant neutrophil chemoattractant in the early phase of ARDS. 相似文献