全文获取类型
收费全文 | 4475篇 |
免费 | 311篇 |
国内免费 | 43篇 |
学科分类
医药卫生 | 4829篇 |
出版年
2024年 | 12篇 |
2023年 | 56篇 |
2022年 | 108篇 |
2021年 | 184篇 |
2020年 | 122篇 |
2019年 | 143篇 |
2018年 | 148篇 |
2017年 | 129篇 |
2016年 | 146篇 |
2015年 | 182篇 |
2014年 | 220篇 |
2013年 | 265篇 |
2012年 | 347篇 |
2011年 | 344篇 |
2010年 | 170篇 |
2009年 | 197篇 |
2008年 | 276篇 |
2007年 | 275篇 |
2006年 | 246篇 |
2005年 | 237篇 |
2004年 | 213篇 |
2003年 | 206篇 |
2002年 | 167篇 |
2001年 | 43篇 |
2000年 | 35篇 |
1999年 | 32篇 |
1998年 | 44篇 |
1997年 | 22篇 |
1996年 | 19篇 |
1995年 | 21篇 |
1994年 | 21篇 |
1993年 | 13篇 |
1992年 | 24篇 |
1991年 | 17篇 |
1990年 | 17篇 |
1989年 | 18篇 |
1988年 | 12篇 |
1987年 | 19篇 |
1986年 | 12篇 |
1985年 | 16篇 |
1984年 | 11篇 |
1983年 | 6篇 |
1982年 | 7篇 |
1981年 | 3篇 |
1980年 | 4篇 |
1977年 | 2篇 |
1975年 | 2篇 |
1969年 | 3篇 |
1968年 | 5篇 |
1967年 | 2篇 |
排序方式: 共有4829条查询结果,搜索用时 0 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.
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
4.
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
5.
In a recent paper, we showed that the number of endoneurial microvessels per square millimeter and the average luminal area and size distribution of these microvessels are not significantly different in sural nerves of patients with diabetes mellitus as compared to control subjects. Mural area, especially the component due to basement membrane reduplication and cellular debris, was unequivocally increased in diabetes mellitus. Because these latter changes are associated with a decrease in periendothelial cell area, we hypothesized that cellular degeneration, especially of pericytes, may account for basement membrane reduplication and increased frequency of cellular debris. In the present study, we showed that endoneurial microvessels undergo a statistically significant increase in basement membrane area, mural area, and frequency of cellular debris in diabetics without polyneuropathy and an even greater increase in diabetics with polyneuropathy. We also found that duration of diabetes mellitus was significantly associated with area occupied by reduplicated basement membrane and cellular debris, but not with mural and periendothelial area. None of the examined measurements was associated with age. Since the microvessel abnormalities we describe are already present before the development of polyneuropathy and increase with severity of polyneuropathy, it is likely that they reflect functional derangements of pericytes and microvessel function which precede and might be implicated in fiber degeneration. 相似文献
6.
Histopathologic parameters in predicting lymph node metastasis of supraglottic laryngeal carcinoma. A systematic clinical-pathological study was performed on fifty-three resected cases of supraglottic laryngeal squamous cell carcinoma, followed up for at least 5 years. The aim of the research was to evaluate histopathologic parameters in predicting lymph node metastasis (N+) as expression of biological malignancy of the neoplasm. The following neoplastic microscopical features were studied: histopathologic and cytologic grading, pattern of growth, peritumoral inflammatory infiltrate, stromal reaction, tumoral necrosis. The results are as follows: stromal reaction and cytologic grading are not useful to identify N+ and N- cases. Cases with high and low degree of differentiation (Broder's grading) are significantly correlated respectively to low (14.3%) and high (70%) incidence of lymph node metastasis (p less than 0.03). A clear correlation is present between the pattern of growth "pushing" and lacking of node metastasis (84.6%). A favorable prognosis significance seems to be linked with the presence of peritumoral lymphoplasmocytic infiltrate, which results to be a marker of cases in which lymph node metastasis incidence is very low (5.5%; p less than 0.001). On the contrary lymph node metastasis incidence increase when tumoral necrosis is present (76.5%; p less than 0.001). 相似文献
7.
Both Human Immunodeficiency Virus Cellular DNA Sequencing and Plasma RNA Sequencing Are Useful for Detection of Drug Resistance Mutations in Blood Samples from Antiretroviral-Drug-Naive Patients 下载免费PDF全文
8.
9.
We report a case of cutaneous myxoid melanoma in a 61-year-old man. Histologically, the tumor, which showed an adjacent intraepidermal proliferation of atypical melanocytes, was composed of spindle-shaped and epithelioid cells with atypical nuclei, arranged in lobules and embedded in a prominent myxoid stroma. Primary cutaneous myxoid melanoma is rare: we found only one other example in the literature. 相似文献
10.
Novelli A Valente EM Bernardini L Ceccarini C Sinibaldi L Caputo V Cavalli P Dallapiccola B 《European journal of human genetics : EJHG》2004,12(7):579-583
Brody disease is a rare muscle disorder characterized by exercise-induced impairment in muscle relaxation, due to a markedly reduced influx of calcium ions in the sarcoplasmic reticulum. A subset of autosomal recessive families harbour mutations in the ATP2A1 gene, encoding the fast-twitch skeletal muscle sarcoplasmic reticulum Ca(2+) ATPase (SERCA1). Rare autosomal dominant families have been described, in which ATP2A1 was excluded as the causative gene, further supporting genetic heterogeneity. We report four individuals from a three-generation Italian family with a clinical phenotype of Brody disease, in which linkage analysis excluded ATP2A1 as the responsible gene. The disease cosegregates in an autosomal dominant fashion with an apparently balanced constitutional chromosome translocation (2;7)(p11.2;p12.1), suggesting a causal relationship between the rearrangement and the phenotype. FISH analysis using YAC and PAC clones as probes refined the breakpoint regions to genomic segments of about 164 and 120 kb, respectively, providing a possible clue to pinpoint the location of a novel gene responsible for this rare muscle disorder. 相似文献