全文获取类型
收费全文 | 4388篇 |
免费 | 320篇 |
国内免费 | 21篇 |
专业分类
耳鼻咽喉 | 25篇 |
儿科学 | 131篇 |
妇产科学 | 122篇 |
基础医学 | 748篇 |
口腔科学 | 67篇 |
临床医学 | 436篇 |
内科学 | 826篇 |
皮肤病学 | 107篇 |
神经病学 | 444篇 |
特种医学 | 100篇 |
外科学 | 529篇 |
综合类 | 23篇 |
一般理论 | 4篇 |
预防医学 | 458篇 |
眼科学 | 33篇 |
药学 | 295篇 |
中国医学 | 7篇 |
肿瘤学 | 374篇 |
出版年
2023年 | 14篇 |
2022年 | 39篇 |
2021年 | 93篇 |
2020年 | 53篇 |
2019年 | 82篇 |
2018年 | 92篇 |
2017年 | 61篇 |
2016年 | 82篇 |
2015年 | 93篇 |
2014年 | 122篇 |
2013年 | 237篇 |
2012年 | 278篇 |
2011年 | 242篇 |
2010年 | 177篇 |
2009年 | 164篇 |
2008年 | 261篇 |
2007年 | 292篇 |
2006年 | 272篇 |
2005年 | 300篇 |
2004年 | 227篇 |
2003年 | 256篇 |
2002年 | 269篇 |
2001年 | 36篇 |
2000年 | 36篇 |
1999年 | 60篇 |
1998年 | 64篇 |
1997年 | 51篇 |
1996年 | 58篇 |
1995年 | 44篇 |
1994年 | 39篇 |
1993年 | 33篇 |
1992年 | 31篇 |
1991年 | 21篇 |
1990年 | 28篇 |
1989年 | 20篇 |
1988年 | 15篇 |
1987年 | 21篇 |
1986年 | 18篇 |
1985年 | 18篇 |
1984年 | 20篇 |
1983年 | 19篇 |
1982年 | 32篇 |
1981年 | 20篇 |
1980年 | 24篇 |
1979年 | 23篇 |
1978年 | 18篇 |
1976年 | 13篇 |
1975年 | 14篇 |
1974年 | 14篇 |
1971年 | 18篇 |
排序方式: 共有4729条查询结果,搜索用时 10 毫秒
1.
2.
Adolf Pfefferbaum Edith V. Sullivan Margaret J. Rosenbloom Paula K. Shear Daniel H. Mathalon Kelvin O. Lim 《Psychiatry Research: Neuroimaging》1993,50(4):257-274
This cross-sectional study used a semi-automated analysis technique to quantify regional brain cerebrospinal fluid (CSF) volumes derived from computed tomography (CT) in 84 healthy men ranging from 21 to 82 years of age and 28 patients meeting Research Diagnostic Criteria for alcohol dependence. The goals were to replicate an earlier CT study of an independent sample of alcoholic and control subjects (Pfefferbaum et al., 1988a; Zipursky et al., 1988) and to compare CT assessments of brain changes with magnetic resonance imaging (MRI) assessments made in the same alcoholic patients (Pfefferbaum et al., 1992). Regional brain changes associated with normal aging were derived by regression analysis, using CT data collected from the healthy control subjects. As in the earlier CT study and in the concurrent MRI study, ventricular and sulcal CSF volumes in alcoholic patients were greater than would be expected for their age. Furthermore, the present CT study replicated the previous CT and MRI findings of a positive relationship between age and CSF volume enlargement in alcoholic patients over and above the normal age-related increase in CSF volume, suggesting greater vulnerability of the aging brain to alcohol. Comparison of CT-and MRI-derived estimates of ventricular and cortical sulcal volume revealed high correlations (>0.80). MRI and CT produced similar absolute ventricular volumes, while MRI produced larger sulcal volume estimates than did CT. The difference in sulcal volume estimate may be due to differences between CT and MRI in slice thickness and sensitivity to partial volume effects. 相似文献
3.
Ruth Ladurner Gerald Brandacher Wolfgang Steurer Stefan Schneeberger Claudia Bösmüller Martin Clemens Freund Alfons Kreczy Alfred Königsrainer Raimund Margreiter 《Transplant international》2003,16(12):885-889
Fungal infections still represent a serious complication after organ transplantation. Early diagnosis and aggressive treatment are crucial. Because of the many diagnostic problems involved, we present a case of mucormycosis--primarily affecting the paranasal sinuses with later intracranial extension--in a highly immunized recipient of a third renal transplant. Although fungal infection was suspected from various imaging techniques, only the detection of typical fungal hyphae in the infected tissue was diagnostic. Neither the blood tests and cerebrospinal fluid examinations performed nor cultures from maxillary sinus fluid were of any diagnostic help. Surgical debridement from a transnasal as well as an intracranial approach and systemic amphotericin B together with the discontinuation of immunosuppression after removal of the rejected graft were able to save the patient. This case stresses the importance of early diagnosis that can only be made from tissue biopsies and allows appropriate timely treatment. 相似文献
4.
Summary A simple mechanical model using a piston to produce localized cerebral contusions in pigs, is presented.The precision and reproducibility of the method are described by the biomechanical and pathological results.There are only pathological changes with haemorrhage and laceration close to the place of entry of the piston. The changes in the physiological parameters also indicate that the damage is focal.In this model, when kept intact, the dura mater offers considerable protection as no pathological changes in the brain are observed even when the energy at the time of the contusion is increased to twice the values which, when the dura is open, cause considerable damage. 相似文献
5.
6.
Tetrahydrobiopterin Attenuates Microvascular Reperfusion Injury Following Murine Pancreas Transplantation 总被引:1,自引:0,他引:1
M. Maglione M. Hermann P. Hengster S. Schneeberger W. Mark P. Obrist G. Werner-Felmayer E. R. Werner R. Margreiter G. Brandacher 《American journal of transplantation》2006,6(7):1551-1559
In this study we investigated the effect of tetrahydrobiopterin (BH4), an essential cofactor for nitric oxide synthases, on ischemia-reperfusion injury (IRI) following murine pancreas transplantation. Pancreatic grafts were exposed to prolonged cold ischemia times (CIT) and different treatment regimens: normal saline (S), S + 16 h CIT, BH4 50 mg/kg + 16 h CIT. Nontransplanted animals served as controls. Graft microcirculation was analyzed by means of functional capillary density (FCD) and capillary diameters (CD) after 2 h reperfusion using intravital microscopy. Quantification of inflammatory responses (mononuclear infiltration) and endothelial disintegration (edema formation) was done by histology (hematoxylin and eosin), and peroxynitrite formation assessed by nitrotyrosine immunostaining. FCD was significantly reduced after prolonged CIT, paralleled by increased peroxynitrite formation as compared with controls (all p < 0.05). Microcirculatory changes correlated significantly with intragraft peroxynitrite generation (Spearman: r = -0.56; p < 0.01). Pancreatic grafts treated with BH4 displayed markedly higher FCD values (p < 0.01) and abrogated nitrotyrosine staining (p = 0.03). CD were not significantly different in any group. Histology showed increased inflammation, interstitial edema, hemorrhage, acinar vacuolization and focal areas of necrosis after 16 h CIT, which was diminished by BH4 administration (p < 0.01). BH4 treatment significantly reduces post-ischemic deterioration of microcirculation as well as histologic damage and might be a promising novel strategy in attenuating IRI following pancreas transplantation. 相似文献
7.
Xiaohua He Edith V Sullivan Roger K Stankovic Clive G Harper Adolf Pfefferbaum 《Neuropsychopharmacology》2007,32(10):2207-2216
The relative roles of alcohol and thiamine deficiency in causing brain damage remain controversial in alcoholics without the Wernicke-Korsakoff syndrome. Experimental control over alcohol consumption and diet are impossible in humans but can be accomplished in animal models. This experiment was designed to differentiate the separate and combined effects on the macro- and ultrastructure of the corpus callosum of thiamine deficiency and voluntary alcohol consumption. Adult male alcohol-preferring (P) rats (9 chronically alcohol-exposed and 9 water controls) received a thiamine-deficient diet for 2 weeks. There were four groups: five rats previously exposed to alcohol were treated with pyrithiamine (a thiamine phosphorylation inhibitor); five rats never exposed to alcohol were treated with pyrithiamine; four alcohol-exposed rats were treated with thiamine; and four rats never exposed to alcohol were treated with thiamine. On day 14, thiamine was restored in all 18 rats; 2 weeks later the 10 pyrithiamine-treated rats received intraperitoneal thiamine. The rats were perfused 61 days post-pyrithiamine treatment at age 598 days. Brains were dissected and weight and volumes were calculated. Sagittal sections were stained to measure white matter structures. The corpus callosum was examined using transmission electron microscopy to determine density of myelinated fibers, fiber diameter, and myelin thickness. The corpus callosum in the alcohol/pyrithiamine group was significantly thinner, had greater fiber density, higher percentage of small fibers, and myelin thinning than in the alcohol/thiamine and water/thiamine groups. Several measures showed a graded effect, where the alcohol/pyrithiamine group had greater pathology than the water/pyrithiamine group, which had greater pathology than the two thiamine-replete groups. Across all 16 rats, thinner myelin sheaths correlated with higher percentage of small fibers. Myelin thickness and axon diameter together accounted for 71% of the variance associated with percentage of small fibers. Significant abnormalities in the alcohol/pyrithiamine group and lack of abnormality in the alcohol-exposed/thiamine-replete group indicate that thiamine deficiency caused white matter damage. The graded abnormalities across the dually to singly treated animals support a compounding effect of alcohol exposure and thiamine depletion, and indicate the potential for interaction between alcohol and thiamine deficiency in human alcohol-related brain damage. 相似文献
8.
Regina Kirchweger Robert Zeillinger Christian Schneeberger Paul Speiser Genevive Louason Charles Theillet 《International journal of cancer. Journal international du cancer》1994,56(2):193-199
Chromosome 17 is a frequent target during breast-cancer formation and progression. It has been shown to be affected by allele losses at multiple sites, as well as by DNA amplification. Our aim was to delineate a map of the genetic alterations on chromosome 17 in a given set of breast tumors. To this end we analyzed 151 pairs of tumor and cognate lymphocyte DNAs by Southern blotting with 5 RFLP or VNTR probes and by PCR at 8 CA repeat polymorphic loci for LOHs. Moreover, we studied DNA amplification of the evi2, erbB2, thra1, gcsf and rara genes. Data presented here point strongly to the existence of 5 distinct regions of allele losses on chromosome 17:2 on 17p, 3 on 17q. Of the 2 regions on 17p, one involves tp53 while the second is located more distally toward the telomere. LOH was found in 45.9% and 58.8% respectively. The 3 regions on 17q are located: (i) on the proximal portion of the long arm band q21, corresponding to the brcal region; (ii) in a central region defined by the marker D17S74; (iii) on the distal part of 17q (band q25) characterized by losses of the marker D17S24. Each of these regions presented respectively allele losses in 47.5%, 33.3% and 40.8% of the informative tumors. Whereas some tumors presented patterns of LOH consistent with the loss of a complete chromosomal arm or of large portions of the chromosome, a high proportion of the analyzed tumors showed interstitial losses. Amplifications were found in 15% of the tumors and were centered around erbB2. An altered chromosome 17 (bearing an LOH or a DNA amplification) was found in more than 80% of the breast tumor set analyzed here and multiple anomalies affecting this chromosome were often detected in the same sample. 相似文献
9.
Elisabeth M Weiss Edith Stadelmann Christian G Kohler Colleen M Brensinger Karen A Nolan Herbert Oberacher Walther Parson Florian Pitterl Harald Niederst?tter Georg Kemmler Hartmann Hinterhuber Josef Marksteiner 《Journal of the International Neuropsychological Society》2007,13(5):881-887
The catechol-O-methyltransferase (COMT) Val158Met polymorphism modulates executive functions and working memory and recent neuroimaging studies implicate an association with emotional processing. We examined the relationship between the COMT Val158Met polymorphism and facial emotion recognition and differentiation in 100 healthy individuals. Compared to Met homozygosity, Val homozygosity was associated with better and faster recognition of negative facial expressions such as anger and sad. Our study provides evidence for a possible influence of the COMT polymorphism on emotion recognition abilities in healthy subjects. Additional research is needed to further define the neurocognitive phenotypes associated with COMT polymorphisms. 相似文献
10.
Håkan Eriksson Joakim Tedroff Karl-Åke Thuomas Sten-Magnus Aquilonius Per Hartvig Karl-Johan Fasth Peter Bjurling Bengt Långström Karl-Göran Hedström Edith Heilbronn 《Archives of toxicology》1992,66(6):403-407
A series of positron emission tomography scans was made on two monkeys during a 16-month period when they received manganese(IV)oxide by subcutaneous injection. The distribution of [11C]-nomifensine uptake, indicating dopamine terminals, was followed in both monkey brains. The brain distributions of [11C]-raclopride, demonstrating D2 dopamine receptors, and [11C]-l-dopa, as a marker of dopamine turnover, were followed in one monkey each. The monkeys developed signs of poisoning namely unsteady gait and hypoactivity. The [11C]-nomifensine uptake in the striatum was reduced with time and reached a 60% reduction after 16 months exposure. This supports the suggestion that dopaminergic nerve endings degenerate during manganese intoxication. The [11C]-l-dopa decarboxylation was not significantly altered indicating a sparing of [11C]-l-dopa decarboxylation during manganese poisoning. A transient decrease of [11C]-raclopride binding occurred but at the end of the study D2-receptor binding had returned to starting values. The magnetic resonance imaging (MRI) revealed that the manganese accumulated in the globus pallidus, putamen and caudate nucleus. There were also suggestions of gliosis/edema in the posterior limb of the internal capsule. MRI might be useful to follow manganese intoxication in humans as long as the scan is made within a few months of exposure to manganese, i. e. before a reversal of the manganese accumulation. 相似文献