全文获取类型
收费全文 | 6703篇 |
免费 | 441篇 |
国内免费 | 57篇 |
专业分类
耳鼻咽喉 | 34篇 |
儿科学 | 165篇 |
妇产科学 | 159篇 |
基础医学 | 863篇 |
口腔科学 | 76篇 |
临床医学 | 500篇 |
内科学 | 1774篇 |
皮肤病学 | 311篇 |
神经病学 | 764篇 |
特种医学 | 181篇 |
外科学 | 852篇 |
综合类 | 13篇 |
一般理论 | 1篇 |
预防医学 | 295篇 |
眼科学 | 49篇 |
药学 | 457篇 |
中国医学 | 8篇 |
肿瘤学 | 699篇 |
出版年
2024年 | 15篇 |
2023年 | 72篇 |
2022年 | 128篇 |
2021年 | 218篇 |
2020年 | 159篇 |
2019年 | 183篇 |
2018年 | 196篇 |
2017年 | 166篇 |
2016年 | 186篇 |
2015年 | 220篇 |
2014年 | 304篇 |
2013年 | 358篇 |
2012年 | 492篇 |
2011年 | 450篇 |
2010年 | 241篇 |
2009年 | 254篇 |
2008年 | 358篇 |
2007年 | 360篇 |
2006年 | 345篇 |
2005年 | 336篇 |
2004年 | 293篇 |
2003年 | 294篇 |
2002年 | 248篇 |
2001年 | 114篇 |
2000年 | 115篇 |
1999年 | 98篇 |
1998年 | 70篇 |
1997年 | 49篇 |
1996年 | 44篇 |
1995年 | 47篇 |
1994年 | 47篇 |
1993年 | 26篇 |
1992年 | 74篇 |
1991年 | 65篇 |
1990年 | 52篇 |
1989年 | 58篇 |
1988年 | 57篇 |
1987年 | 53篇 |
1986年 | 36篇 |
1985年 | 48篇 |
1984年 | 28篇 |
1983年 | 18篇 |
1982年 | 16篇 |
1980年 | 17篇 |
1978年 | 14篇 |
1977年 | 15篇 |
1973年 | 14篇 |
1972年 | 14篇 |
1971年 | 23篇 |
1967年 | 13篇 |
排序方式: 共有7201条查询结果,搜索用时 15 毫秒
1.
2.
Caterina Proto Daniela Romualdi Rosa Maria Cento Rosario S Spada Giuseppina Di Mento Raffaele Ferri Antonio Lanzone 《Gynecological endocrinology》2006,22(4):213-218
BACKGROUND: In the central nervous system, several neuropeptides are believed to be involved in the pathophysiology of Alzheimer's disease (AD). Indeed, previous studies have documented that glucagon-like peptide 1 (GLP-1) possesses neurotropic properties and can reduce amyloid-beta peptide levels in the brain in vivo. Moreover, the concentrations of neuropeptide Y (NPY) seem to be altered in the cerebrospinal fluid of patients with AD and in subjects with major depression. Finally, among the modifications induced by aging, a dysregulation of the ghrelin-growth hormone (GH) system has been reported. METHODS: We investigated the plasma concentrations of these neuropeptides in 14 subjects with AD. Data obtained from these patients were compared with data from an age- and weight-matched healthy group. RESULTS: No significant differences were found between the two groups in relation to plasma levels of GLP-1, NPY, ghrelin and GH. Peripheral NPY concentrations were positively correlated with ghrelin levels in both groups, and with plasma GLP-1 concentration only in controls. CONCLUSION: On the basis of our results, peripheral levels of these neuropeptides seem not to serve as biochemical markers of AD. 相似文献
3.
4.
5.
The aim of this work is to evaluate citrate in a group of patients with calcium oxalate urolithiasis and in a control group
for detecting possible differences between the two groups. The mean urinary concentration in the stone-formers was found significantly
lower than in the controls. Particularly interesting was the correlation study between citrate and calcium. It was found that
patients with hypocitraturia have hypercalciuria. Thus, it is particularly interesting to point out the importance of citrate
in preventing the risk of lithiasis in the group of stone-formers studied by us. 相似文献
6.
Daily nutrient intake represents a modifiable determinant of nutritional status in chronic haemodialysis patients. 总被引:2,自引:0,他引:2
Vincenzo Bellizzi Biagio R Di Iorio Vincenzo Terracciano Roberto Minutolo Carmela Iodice Luca De Nicola Giuseppe Conte 《Nephrology, dialysis, transplantation》2003,18(9):1874-1881
BACKGROUND: In maintenance haemodialysis patients, daily food intake is changeable; however, its relationship with nutritional status is unexplored. This study aimed to evaluate the isolated, long-term effect of daily nutrient intake on nutritional status in haemodialysis patients. METHODS: We performed a prospective 1-year controlled study in 27 chronic haemodialysis patients, without recognized risk factors for malnutrition. Each day for 1 week, four times in the year, we measured protein nitrogen appearance, and assessed dietary protein (DPI) and energy (DEI) intake from dietary diaries. We compared the nutritional outcome of patients spontaneously reducing nutrient intake below the threshold of 0.8 g/kg body weight/day for DPI and 25 kcal/kg body weight/day for DEI during the week (LOW, n = 8), with controls at adequate nutrient intake (CON, n = 19). An interventional 6-month study was then carried out in LOW to verify the cause-effect relationship. RESULTS: All patients showed a day-by-day reduction of whole nutrient intake during interdialytic period, which was mostly relevant in the third interdialytic day (L3). During the 1-year study, even in the presence of adequate dialysis dose and normal inflammatory indexes, body weight (68.0 +/- 5.5 to 65.8 +/- 5.9 kg), serum albumin (3.96 +/- 0.07 to 3.66 +/- 0.06 g/dl) and creatinine (9.2 +/- 1.1 to 8.1 +/- 0.7 mg/dl) significantly decreased in LOW but not in CON. Diaries evidenced in LOW a reduced number of meals at L3 that was explained by the fear of excessive interdialytic weight gain. During the interventional study, daily DPI and DEI increased at L3; this was associated with a significant increment of body weight, and serum albumin and creatinine levels. CONCLUSIONS: In maintenance haemodialysis patients the persistent, marked reduction of daily nutrient intake, even if limited to a single day of the week, is an independent determinant of reversible impairment of nutritional status. 相似文献
7.
Paolo Martinelli Giovanni Rizzo David Manners Caterina Tonon Fabio Pizza Claudia Testa Cesa Scaglione Bruno Barbiroli Raffaele Lodi 《Movement disorders》2007,22(8):1182-1185
The pathophysiology of essential tremor (ET) is unknown. PET and fMRI studies have revealed bilateral activation and (1)H-MRS studies metabolic abnormalities in the cerebellum and other functionally related brain structures in ET. Diffusion-weighted imaging (DWI) was used to search for evidence of tissue integrity abnormalities in these areas in ET patients and 10 matched controls by calculating water apparent diffusion coefficients (ADCs). Regions of interest included the left and right cerebellum, red nucleus, thalamus, caudate, putamen, pallidum, and frontal white matter. Histograms of ADCs were generated for all pixels in the infratentorial compartment and manually segmented areas corresponding to brainstem, vermis, and cerebellar hemispheres. ADC values were similar in all brain areas in patients and controls. Our study did not detect changes affecting the investigated brain regions in ET patients. These findings argue against major structural damage in the ET brain, although more subtle neurodegenerative changes cannot be ruled out. 相似文献
8.
Advances in processing of surface myoelectric signals: Part 1 总被引:10,自引:0,他引:10
R. Merletti Dip. di Elettronica L. R. Lo Conte 《Medical & biological engineering & computing》1995,33(3):362-372
During sustained voluntary or electrically elicted muscle contractions the surface myoelectric signal is nonstationary and
it undergoes progressive changes reflecting the modifications of the motor unit action potentials and their propagation velocity.
In particular, during sustained electrical stimulation, the evoked signals show progressive amplitude, time scaling and shape
modification. The quantitative evaluation of these changes is important for non-invasive muscle characterisation and may be
performed in either the time or frequency domain using parametric and nonparametric spectral analysis as well as alternative
methodologies. The paper introduces the detection techniques, reviews and compares the methods of spectral estimation based
on FFT and autoregressive models, and discusses their applications and limitations in extracting information from the surface
myoelectric signal with particular regard to myoelectric manifestations of localised muscle fatigue during sustained contractions. 相似文献
9.
M Gayral-Taminh I Delobbe M A Mignon-Conte M Dueymes J J Conte 《Journal of clinical & laboratory immunology》1992,38(3):111-135
Several sets of data suggest that specific classes of anti-DNA antibodies could be implicated in the genesis of glomerular lesions in SLE. The goal of this work is to investigate if this pathogenic role could be related to the antibodies' genetic origin--from BALB/c or NZBxNZW/F1 mice--or to their physiological origin--induced either by DNA or by polyclonal B cell activation in normal mice. For this purpose, anti-DNA antibody hybridoma clones produced from different origins were subcutaneously injected in BALB/c or NZBxNZW/F1 female mice, followed by studies of immunological parameters and kidney lesions. Results concur that the induced anti-DNA antibodies can play a role in fatal disease development, related to clonal specificity but not to the way of stimulation which was either polyclonal B cell activation or DNA immunization. Also, they emphasize the possible very lethal role of serum circulating DNA. 相似文献
10.
Claudia Giaroli Gianfranco Riccò Gianni Vecchi Stefano Belli Caterina Bruno Mario Grignoli Silvia Candela Salvatore Minisci Roberto Poletti Guiseppina Venturi Antonio Ziccardi Pietro Comba 《International archives of occupational and environmental health》1994,66(1):7-11
The present study describes cause-specific mortality of asbestos cement workers in the Emilia Romagna region of Italy. The cohort included workers in ten factories, most of which started operating between 1955 and 1965. Asbestos, mainly chrysotile, constituted 10%–20% of the dry component of the mixture. Crocidolite range between 5% and 50% of total asbestos. Asbestos concentrations up to 44 ff/cc were reported prior to 1975, while in recent years they have usually been below 0–1 ff/cc. The cohort included 3341 workers who had at some time been employed in the ten factories under study. Their mortality experience was compared with that of the population resident in Emilia Romagna. Vital status was ascertained at 1989. Seventy-three subjects were lost to followup (2.2%). Mortality from all causes and from all types of cancer was increased in the cohort. Malignant neoplasms of the respiratory tract showed a significant increase (SMR: 134; 90% confidence interval: 101–175; 40 observed) due to lung cancer (SMR: 124; 90% confidence interval: 91–166; 33 observed) and neoplasms of the pleura, mediastinum, and other parts of the respiratory tract (SMR: 602; 90% confidence interval 237–1267; 5 observed). The discrepancy between observed and expected mortality mainly concerned subjects with at least 20 years of employment in the factories. Five more cases of histologically confirmed mesothelioma occurred after the end of follow-up. 相似文献