全文获取类型
收费全文 | 2303篇 |
免费 | 355篇 |
国内免费 | 10篇 |
专业分类
耳鼻咽喉 | 3篇 |
儿科学 | 68篇 |
妇产科学 | 283篇 |
基础医学 | 181篇 |
口腔科学 | 30篇 |
临床医学 | 870篇 |
内科学 | 247篇 |
皮肤病学 | 57篇 |
神经病学 | 91篇 |
特种医学 | 262篇 |
外科学 | 124篇 |
综合类 | 57篇 |
一般理论 | 1篇 |
预防医学 | 114篇 |
眼科学 | 10篇 |
药学 | 93篇 |
中国医学 | 2篇 |
肿瘤学 | 175篇 |
出版年
2023年 | 44篇 |
2021年 | 14篇 |
2020年 | 38篇 |
2019年 | 27篇 |
2018年 | 62篇 |
2017年 | 96篇 |
2016年 | 88篇 |
2015年 | 108篇 |
2014年 | 123篇 |
2013年 | 121篇 |
2012年 | 62篇 |
2011年 | 94篇 |
2010年 | 119篇 |
2009年 | 115篇 |
2008年 | 67篇 |
2007年 | 76篇 |
2006年 | 65篇 |
2005年 | 49篇 |
2004年 | 39篇 |
2003年 | 46篇 |
2002年 | 31篇 |
2001年 | 57篇 |
2000年 | 28篇 |
1999年 | 65篇 |
1998年 | 96篇 |
1997年 | 111篇 |
1996年 | 117篇 |
1995年 | 98篇 |
1994年 | 65篇 |
1993年 | 55篇 |
1992年 | 41篇 |
1991年 | 36篇 |
1990年 | 21篇 |
1989年 | 47篇 |
1988年 | 43篇 |
1987年 | 25篇 |
1986年 | 35篇 |
1985年 | 34篇 |
1984年 | 19篇 |
1983年 | 16篇 |
1982年 | 23篇 |
1981年 | 17篇 |
1980年 | 17篇 |
1979年 | 4篇 |
1978年 | 19篇 |
1977年 | 15篇 |
1976年 | 14篇 |
1975年 | 15篇 |
1919年 | 3篇 |
1900年 | 6篇 |
排序方式: 共有2668条查询结果,搜索用时 15 毫秒
1.
2.
D Van Neste† RM Trüeb‡ 《Journal of the European Academy of Dermatology and Venereology》2006,20(5):578-583
BACKGROUND: Computer-assisted image analysis has been proposed for human hair growth studies. METHODS: The performances of Trichoscan, a commercially available automated system combining epiluminiscence microscopy with digital image analysis, developed for office-based hair growth measurements, have been evaluated comparatively on the same skin sites using standardized photographic equipment and calibrated processing for contrast-enhanced phototrichogram (CE-PTG) analysis. This reference method has been validated with scalp biopsies and histological examination of serial sectioning. RESULTS: Besides edge effects, hair fibres escaped the Trichoscan analysis for various reasons including, but not limited to, thickness, pigmentation, closeness and crossing. CONCLUSION: Most of these problems have been identified in the late 1980s and remain largely unsolved by the processing software that was evaluated in 2004. Therefore claims promoting the Trichoscan method for accurate hair measurements in clinical trials on scalp and body hair are not supported by the present investigation. The speed at which the analysis is performed is outweighed by the errors in signal detection. Therefore we suggest that improvements must be clearly documented before Trichoscan is established for quantified diagnostic purposes and detailed hair cycle monitoring during hair trials. 相似文献
3.
4.
A genetic analysis of mammalian neuronal physiology might now be possible due to the development of defective herpes simplex virus vectors, which allow gene transfer directly into mature neurons, in culture or in the adult brain. Genetically altered proteins that play critical roles in neuronal physiology, including those responsible for the generation of action potentials, synthesis and release of neurotransmitters, and signal transduction enzymes, can now be stably expressed in neurons. The effect of such altered proteins on neuronal physiology can therefore be examined, using the tools of modern neuroscience. Genetic manipulation is biochemically specific and stable, and can be targeted both to a particular cell type and to a particular subregion of the cell to yield insights into the molecular basis for specific brain functions. 相似文献
5.
A quantitative method of analyzing the interaction of slightly selective radioligands with multiple receptor subtypes 总被引:6,自引:0,他引:6
Subclasses of receptors exist for most neurotransmitters. Frequently, two subtypes of receptors coexist in the same tissue and, in some cases, they mediate the same physiological response. In tissues with two classes of binding sites for a given hormone, an estimate of the proportion of each class of binding sites is obtained by inhibiting the binding of a single concentration of a radioligand with a selective unlabeled ligand. Accurate estimates of the density of each class of receptors will only be obtained, however, if the radioligand is entirely nonselective. Selectivity of just 2- to 3-fold can markedly influence the results of subtype analysis. The conclusion that a radioligand is nonselective is usually based on the results of a saturation binding curve. If Scatchard analysis of such data results in a linear plot, then it is concluded that the radioligand is nonselective. However, Scatchard analysis cannot distinguish between a radioligand that is nonselective and one that is slightly selective. The use of a slightly selective radioligand can lead to errors of 50% or more, depending on the concentration of the radioligand relative to the Kd values of the two classes of sites. A new analytical method has been developed that can be used to quantitate 2- to 3-fold differences in the affinity of two distinct classes of binding sites for a radioligand. This new approach requires that a series of inhibition experiments with a selective unlabeled ligand be performed in the presence of increasing concentrations of the radioligand. Analysis of the resulting inhibition curves, utilizing the mathematical modeling program MLAB on the PROPHET system, yields accurate estimates of the density of each class of receptor as well as the affinity of each receptor for the labeled and unlabeled ligands. This approach was used to determine whether 125I-iodopindolol shows selectivity for beta 1- or beta 2-adrenergic receptors. A series of inhibition curves was generated with the unlabeled ligands ICI 89,406 (beta 1-selective) and ICI 118,551 (beta 2-selective), using membranes prepared from C6 glioma cells. These cells contain both beta 1- and beta 2-adrenergic receptors. 125I-Iodopindolol was determined to be 3-fold selective for beta 2-adrenergic receptors. Since the sensitivity of this approach is superior to that of Scatchard analysis, it is likely that other radioligands, previously thought to be nonselective, will be shown to be selective when analyzed by this method. 相似文献
6.
V Schleyer† S Radakovic-Fijan‡ S Karrer† T Zwingers§ A Tanew‡ M Landthaler† RM Szeimies† 《Journal of the European Academy of Dermatology and Venereology》2006,20(7):823-828
BACKGROUND: Based on good results in the treatment of superficial skin tumours, since the early 1990s topical photodynamic therapy with aminolaevulinic acid (ALA PDT) has been used for disseminated, inflammatory dermatoses including psoriasis. However, there is still a lack of well-documented trials. OBJECTIVE: A prospective randomized, double-blind phase I/II intrapatient comparison study was conducted in 12 patients to investigate whether topical ALA PDT is an effective treatment for chronic plaque-type psoriasis. METHODS: In each patient three psoriatic plaques were randomly treated with a light dose of 20 J/cm(2) and 0.1%, 1% and 5% ALA, respectively. Treatment was conducted twice a week until complete clearance or for a maximum of 12 irradiations. Therapeutic efficacy was assessed by weekly determination of the psoriasis severity index (PSI). RESULTS: The mean percentage improvement was 37.5%, 45.6% and 51.2% in the 0.1%, 1% and 5% ALA-treated groups, respectively. Irradiation had to be interrupted several times because of severe burning and pain sensation. CONCLUSION: Topical ALA PDT did not prove to be an appropriate treatment option for plaque-type psoriasis due to disappointing clinical efficacy, the time-consuming treatment procedure and its unfavourable adverse event profile. 相似文献
7.
8.
9.
10.
M.M. Bialoskurski MA RN RM C.L. Cox MSc PhD RN & R.D. Wiggins PhD 《Journal of advanced nursing》2002,37(1):62-69
AIM: The aim of this study was to investigate the nature and organization of maternal needs and priorities in a neonatal unit. BACKGROUND: The relationship between maternal needs and priorities appears to be an under studied area in neonatal nursing. METHODS: A quantitative survey was carried out based on 209 mothers with premature infants. Two self-assessment schedules were used: critical care maternal needs inventory (J. Leske, Heart and Lung 15, 27-42) and a ranking scale. The data were analysed with multivariate analysis. FINDINGS: Data analysis revealed clear priorities in maternal needs. In particular the need for accurate infant related information was a priority for 93% of the mothers. Good communication practices with professionals were also valued. The mothers displayed altruistic behaviour, and self-related needs took second place. It is proposed that maternal needs demonstrate a hierarchical organization. CONCLUSION: It is important for nurses to consider the individual needs of the mothers, simply because the satisfaction of these needs is essential for maternal well-being. 相似文献