全文获取类型
收费全文 | 2510篇 |
免费 | 144篇 |
国内免费 | 24篇 |
专业分类
耳鼻咽喉 | 6篇 |
儿科学 | 114篇 |
妇产科学 | 56篇 |
基础医学 | 318篇 |
口腔科学 | 38篇 |
临床医学 | 151篇 |
内科学 | 670篇 |
皮肤病学 | 32篇 |
神经病学 | 479篇 |
特种医学 | 103篇 |
外科学 | 169篇 |
综合类 | 40篇 |
预防医学 | 63篇 |
眼科学 | 9篇 |
药学 | 251篇 |
中国医学 | 10篇 |
肿瘤学 | 169篇 |
出版年
2022年 | 23篇 |
2021年 | 31篇 |
2020年 | 17篇 |
2019年 | 31篇 |
2018年 | 45篇 |
2017年 | 31篇 |
2016年 | 39篇 |
2015年 | 39篇 |
2014年 | 53篇 |
2013年 | 77篇 |
2012年 | 114篇 |
2011年 | 116篇 |
2010年 | 77篇 |
2009年 | 75篇 |
2008年 | 115篇 |
2007年 | 123篇 |
2006年 | 119篇 |
2005年 | 124篇 |
2004年 | 98篇 |
2003年 | 114篇 |
2002年 | 85篇 |
2001年 | 100篇 |
2000年 | 97篇 |
1999年 | 98篇 |
1998年 | 76篇 |
1997年 | 49篇 |
1996年 | 41篇 |
1995年 | 40篇 |
1994年 | 29篇 |
1993年 | 34篇 |
1992年 | 53篇 |
1991年 | 41篇 |
1990年 | 44篇 |
1989年 | 50篇 |
1988年 | 38篇 |
1987年 | 34篇 |
1986年 | 27篇 |
1985年 | 31篇 |
1984年 | 24篇 |
1983年 | 28篇 |
1982年 | 17篇 |
1981年 | 12篇 |
1980年 | 10篇 |
1979年 | 24篇 |
1978年 | 15篇 |
1977年 | 10篇 |
1976年 | 12篇 |
1975年 | 18篇 |
1972年 | 14篇 |
1969年 | 10篇 |
排序方式: 共有2678条查询结果,搜索用时 15 毫秒
1.
L Bernardi A Schneider L Pomidori E Paolucci A Cogo 《The European respiratory journal》2006,27(1):165-171
A very high ventilatory response to hypoxia is believed necessary to reach extreme altitude without oxygen. Alternatively, the excessive ventilation could be counterproductive by exhausting the ventilatory reserve early on. To test these alternatives, 11 elite climbers (2004 Everest-K2 Italian Expedition) were evaluated as follows: 1) at sea level, and 2) at 5,200 m, after 15 days of acclimatisation at altitude. Resting oxygen saturation, minute ventilation, breathing rate, hypoxic ventilatory response, maximal voluntary ventilation, ventilatory reserve (at oxygen saturation = 70%) and two indices of ventilatory efficiency were measured. Everest and K2 summits were reached 29 and 61 days, respectively, after the last measurement. Five climbers summited without oxygen, the other six did not, or succeeded with oxygen (two climbers). At sea level, all data were similar. At 5,200 m, the five summiters without oxygen showed lower resting minute ventilation, breathing rate and ventilatory response to hypoxia, and higher ventilatory reserve and ventilatory efficiency, compared to the other climbers. Thus, the more successful climbers had smaller responses to hypoxia during acclimatisation to 5,200 m, but, as a result, had greater available reserve for the summit. A less sensitive hypoxic response and a greater ventilatory efficiency might increase ventilatory reserve and allow sustainable ventilation in the extreme hypoxia at the summit. 相似文献
2.
Nicola Martinelli Domenico Girelli Paolo Ferraresi Oliviero Olivieri Barbara Lunghi Franco Manzato Roberto Corrocher Francesco Bernardi 《Blood coagulation & fibrinolysis》2007,18(2):125-129
A common factor V gene haplotype, the FVR2 haplotype (FVHR2), has been associated with a reduced cofactor activity in activated protein C-mediated activated factor VIII inactivation. Our aim was to investigate the role of FVHR2 as a possible determinant of factor VIII levels in a population study. A total of 516 individuals (401 men, 115 women; mean age 58.4 +/- 10.8 years) were enrolled within the frame of a regional cardiovascular survey, characterized for factor VIII coagulant activity (FVIII:c) and factor V coagulant activity (FV:c) levels, and genotyped for factor V polymorphisms. In men without signs of overt inflammation, FVHR2 carriers had higher levels of FVIII:c than noncarriers (154 IU/dl, 95% confidence interval = 143-166 versus 142 IU/dl, 95% confidence interval = 138-147; P = 0.045) and were more represented in individuals with high (> or = 150 IU/dl) FVIII:c levels (21.2 versus 10.8%; odds ratio = 2.27, 95% confidence interval = 1.17-4.39 after adjustment for age, blood group and high-sensitivity C-reactive protein levels). In conclusion, this clinical report suggests the common FVHR2 as a possible independent determinant of FVIII:c levels. The report concomitantly addresses the relationship between factor V and factor VIII levels and supports the hypothesis of a mild prothrombotic role of FVHR2 by means of increased factor VIII levels. 相似文献
3.
C. Caramella F. Ferrari M. C. Bonferoni M. E. Sangalli M. De Bernardi Di Valserra F. Feletti M. R. Galmozzi 《Biopharmaceutics & drug disposition》1993,14(2):143-160
Six preparations were considered: three multiple unit dosage forms (micropellets in capsules) (D, E and G) and one matrix tablet (B) were experimental prolonged release formulations, two non-disintegrating tablets (A and C) were commercial products. The in vitro dissolution behaviour of the differing formulations was investigated using the USP XXII paddle apparatus. The in vivo study was effected on a panel of 12 healthy volunteers. The two commercial tablets (A and C) showed mean dissolution time (MDT) of 1.34 and 1.44 h and td of 91 and 92 min, respectively; for prolonged release formulations (B, E, D, and G) MDT ranged between 2.28 and 4.23 h and td between 149 and 291 min. The mean residence time (MRT) was 8.68 and 6.47 h for tablets A and C, respectively; it ranged between 9.62 and 10.24 h for the multiple unit formulations E, D, and G and was 11.27 h for matrix B. Formulation B also showed the higher apparent elimination half-life t1/2 (7.12 h), while apparent t1/2 for all the other formulations were very similar, ranging between 5.04 and 5.28 h. High variability between the various formulations was found for Cmax and AUC values, and no relationships could be established with the type of formulation. An in vitro/in vivo correlation was found for all the formulations examined on the basis of analogous parameters (MDT and MRT); (r = 0.83, p <0.05). In a few cases the Wagner-Nelson deconvolution method was applied to individual plasma level versus time curves and the corresponding absorption curves were obtained. In these cases the in vitro/in vivo correlation was tested on the basis of the comparison of the in vivo absorption curves with the in vitro dissolution profiles. This was accomplished using the ‘Levy's plot’ (per cent released versus per cent absorbed) approach and provided further support for the correlation found. 相似文献
4.
M. Bernardi R. Deslauriers J. Docherty G. Galeazzi L. Rossini P. Rossini 《Autonomic & autacoid pharmacology》1997,17(1):27-34
1 Within the context of neural regulation of the activity of sinus node pacemaker cells, the study of heart rate variability, as explored in the frequency domain by spectral analysis, was proposed about 15 years ago as a quantitative tool for the evaluation of short-term autonomic cardiovascular control. It has since been postulated that the two main oscillations observed, one at low and the other at high frequency, may respectively be markers of sympathetic vs. vagal efferent cardiac activity, and that the low- and high-frequency signals may reflect a reciprocal or ‘push–pull’ relationship between sympathetic and parasympathetic control. 2 In our power spectra assessment, ECG R–R intervals were submitted to fast Fourier transformation analysis in order to study the mechanisms underlying the control of heart beats in rats. Data were acquired in conditions of steady arterial blood pressure and cardiac and respiratory activity (spontaneous or artificially stimulated) in diethyl-ether-anaesthetized and pithed rats, as well as in a group of control rats, all in the presence and absence of l-hyoscyamine. 3 With increasing doses of the parasympathetic antagonist, the fractal dimension of the time-series structure remained stable in most cases. The low-frequency spectral component narrowed with increasing drug doses and the high-frequency band underwent either no, or only very slight, changes. 4 In these rodent assays, the low- and high-frequency signals cannot be interpreted as a push–pull relationship between sympathetic and parasympathetic control. 相似文献
5.
6.
7.
B. Bernardi C. Fonda E. Franzoni E. Marchiani E. Della Guistina R. A. Zimmerman 《Neuroradiology》1994,36(6):477-479
A case of infantile Krabbe's disease was first recognised as areas of relatively increased density on CT in the thalamus lateral geniculate body and dentate nucleus. These sites were subsequently shown on MRI to have a paramagnetic effect, being characterised by short T2 and T1. Subsequent examinations showed development of atrophy and high signal in white matter. 相似文献
8.
Arteriovenous malformations (AVMs) of the spinal cord are a rare occurrence in the pediatric age group. This report describes the successful, complete removal of such a lesion in a boy age 12. The clinico-radiological findings and different treatment modalities of these entities are reviewed. 相似文献
9.
AP de Moraes† ÉÂG de Arruda† MAV Vitoriano† MO de Moraes Filho‡ FÂF Bezerra‡ E de Magalhães Holanda§ MEA de Moraes‡ 《Journal of the European Academy of Dermatology and Venereology》2007,21(5):596-601
BACKGROUND: Seborrhoeic dermatitis (SD) is a common dermatosis in human immunodeficiency virus (HIV)-positive patients, many of whom do not respond satisfactorily to conventional topical treatments such as corticosteroids and antifungals. OBJECTIVE: A pilot study to investigate the efficacy and tolerability of pimecrolimus cream 1% in HIV-positive patients with facial SD. METHODS: In a single-centre study, 21 HIV-infected patients with mild to severe SD were treated twice daily with pimecrolimus cream 1% for 14 days. Thereafter, treatment was discontinued and patients followed up for 5 weeks. Skin involvement at baseline and on days 7, 14, 21, 35 and 49 was assessed using a four-point clinical score and digital photography. MAIN OUTCOME MEASURES: Efficacy and safety of pimecrolimus cream 1% treatment and incidence of relapse in the follow-up phase. Results Marked improvement was seen in clinical parameters at day 7, with >or= 90% patients clear of symptoms at day 14. Relapse was observed at day 35 but signs were milder than at baseline. All patients responded to therapy, despite their immunological status. Pimecrolimus did not alter CD4(+) and CD8(+) T-cell counts or viral load during the treatment period. CONCLUSION: Pimecrolimus cream represents a new, effective therapeutic option for facial SD in HIV patients. 相似文献
10.
Paolo Calabresi Emesto Fedele Antonio Pisani Giovanni Fontana Nicola B. Mercuri Giorgio Bernardi Maurizio Raiteri 《The European journal of neuroscience》1995,7(9):1889-1894
Using a corticostriatal slice preparation, we have recently shown that tetanic stimulation of the corticostriatal pathway produces long-term depression (LTD) of striatal excitatory synaptic transmission. In the present study we have analysed the relationship between LTD and the striatal release of different endogenous transmitters. Samples of perfusate were collected via a small cannula placed just above the surface of the striatal slice close to the recording electrode, and were analysed by HPLC. The high-frequency stimulation (100 Hz, three trains, 3 s duration, 20 s intervals) used to induce LTD caused a significant but transient increase in the release of both excitatory (aspartate and glutamate) and inhibitory (glycine and GABA) amino acid transmitters. Tetanic stimulation also produced a significant, but transient increase in the release of endogenous dopamine. We conclude that the tetanic stimulation of the corticostriatal pathway is able to induce a large but transient release of excitatory amino acids and of dopamine, whose participation in the induction of striatal LTD has been demonstrated previously. Moreover, the maintenance of this form of synaptic plasticity does not seem to require a sustained change in transmitter release. 相似文献