全文获取类型
收费全文 | 8433篇 |
免费 | 566篇 |
国内免费 | 52篇 |
专业分类
耳鼻咽喉 | 44篇 |
儿科学 | 223篇 |
妇产科学 | 249篇 |
基础医学 | 1383篇 |
口腔科学 | 182篇 |
临床医学 | 910篇 |
内科学 | 1680篇 |
皮肤病学 | 182篇 |
神经病学 | 849篇 |
特种医学 | 291篇 |
外国民族医学 | 7篇 |
外科学 | 736篇 |
综合类 | 42篇 |
一般理论 | 2篇 |
预防医学 | 712篇 |
眼科学 | 86篇 |
药学 | 658篇 |
中国医学 | 19篇 |
肿瘤学 | 796篇 |
出版年
2024年 | 11篇 |
2023年 | 64篇 |
2022年 | 113篇 |
2021年 | 216篇 |
2020年 | 153篇 |
2019年 | 203篇 |
2018年 | 210篇 |
2017年 | 171篇 |
2016年 | 239篇 |
2015年 | 244篇 |
2014年 | 350篇 |
2013年 | 416篇 |
2012年 | 676篇 |
2011年 | 802篇 |
2010年 | 421篇 |
2009年 | 379篇 |
2008年 | 606篇 |
2007年 | 652篇 |
2006年 | 607篇 |
2005年 | 581篇 |
2004年 | 493篇 |
2003年 | 402篇 |
2002年 | 390篇 |
2001年 | 54篇 |
2000年 | 45篇 |
1999年 | 68篇 |
1998年 | 83篇 |
1997年 | 79篇 |
1996年 | 65篇 |
1995年 | 45篇 |
1994年 | 44篇 |
1993年 | 32篇 |
1992年 | 31篇 |
1991年 | 14篇 |
1990年 | 9篇 |
1989年 | 6篇 |
1988年 | 5篇 |
1987年 | 5篇 |
1986年 | 10篇 |
1985年 | 8篇 |
1984年 | 7篇 |
1983年 | 8篇 |
1982年 | 4篇 |
1981年 | 3篇 |
1980年 | 4篇 |
1979年 | 3篇 |
1974年 | 2篇 |
1973年 | 2篇 |
1970年 | 4篇 |
1968年 | 2篇 |
排序方式: 共有9051条查询结果,搜索用时 15 毫秒
31.
32.
33.
Kemp S Valianpour F Denis S Ofman R Sanders RJ Mooyer P Barth PG Wanders RJ 《Molecular genetics and metabolism》2005,84(2):144-151
X-linked adrenoleukodystrophy (X-ALD) is a progressive neurodegenerative disorder characterized by the accumulation of saturated and mono-unsaturated very long-chain fatty acids (VLCFA) and reduced peroxisomal VLCFA beta-oxidation activity. In this study, we investigated the role of VLCFA biosynthesis in X-ALD fibroblasts. Our data demonstrate that elongation of both saturated and mono-unsaturated VLCFAs is enhanced in fibroblasts from patients with peroxisomal beta-oxidation defects including X-ALD, and peroxisome biogenesis disorders. These data indicate that enhanced VLCFA elongation is a general phenomenon associated with an impairment in peroxisomal beta-oxidation, and not specific for X-ALD alone. Analysis of plasma samples from patients with X-ALD and different peroxisomal beta-oxidation deficiencies revealed increased concentrations of VLCFAs up to 32 carbons. We infer that enhanced elongation does not result from impaired peroxisomal beta-oxidation alone, but is due to the additional effect of unchecked chain elongation. We demonstrate that elongated VLCFAs are incorporated into complex lipids. The role of chain elongation was also studied retrospectively in samples from patients with X-ALD previously treated with "Lorenzo's oil." We found that the decrease in plasma C26:0 previously found is offset by the increase of mono-unsaturated VLCFAs, not measured previously during the trial. We conclude that evaluation of treatment protocols for disorders of peroxisomal beta-oxidation making use of plasma samples should include the measurement of saturated and unsaturated VLCFAs of chain lengths above 26 carbon atoms. We also conclude that chain elongation offers an interesting target to be studied as a possible mode of treatment for X-ALD and other peroxisomal beta-oxidation disorders. 相似文献
34.
Comparison of broth microdilution,E Test,and agar dilution methods for antibiotic susceptibility testing of Campylobacter jejuni and Campylobacter coli 下载免费PDF全文
A standardized broth microdilution method was compared to the E test and an agar dilution method for the antimicrobial susceptibility testing of Campylobacter jejuni and C. coli isolates. A group of 47 human clinical isolates, 37 isolates from retail poultry, and 29 isolates from living turkeys (total, 113 isolates) was included in the study. These encompassed 92 C. jejuni and 21 C. coli strains. The MICs of six antimicrobial agents were determined by the broth microdilution and E test methods, and the strains of human origin were additionally tested by the agar dilution method. In general, broth microdilution MICs agreed within 1 log(2) MIC increment with 90.0% of E test results and 78.7% of agar dilution test results. The agar dilution method gave much lower gentamicin MICs than the broth microdilution method, but the data were significantly (P < 0.01) correlated and there was 100% agreement in the sensitivities and specificities in the comparison of the tests. The broth microdilution method had the highest sensitivity for analysis of the susceptibilities of Campylobacter to nalidixic acid and trimethoprim-sulfamethoxazole. The MICs of ciprofloxacin and erythromycin complied numerically by all three methods. The classification of the results and the correlation of the data demonstrated a high degree of agreement. All methods were equally suitable for the testing of the sensitivity of Campylobacter to tetracycline. Thus, the broth microdilution method appears to be an easy and reliable method for determination of the MICs of antibiotics for C. jejuni and C. coli, and it may offer an interesting alternative to MIC determination by the agar dilution technique or the E test. 相似文献
35.
36.
37.
Microglial Reaction in the Rat Cerebral Cortex Induced by Cortical Spreading Depression 总被引:4,自引:0,他引:4
Jochen Gehrmann Guenter Mies Petra Bonnekoh Richard Banati Takehiko Iijima Georg W. Kreutzberg Konstantin-Alexander Hossmann 《Brain pathology (Zurich, Switzerland)》1993,3(1):11-17
The response of microglial cells to cortical spreading depression (CSD) was studied in rat brain by immunocytochemistry. CSD was elicited for one hour by the topical application of 4M potassium chloride solution and the microglial reaction examined immunocytochemically after 4, 16, 24 and 72 hours. CSD was sufficient to induce a microglial reaction throughout the cortex at 24 hours. Activated microglial cells furthermore showed a striking de-novo expression of major histocompatibility complex class II antigens. In contrast, no microglial reaction was observed in the cortex of sham-operated animals. This microglial reaction in response to CSD was not associated with histologically detectable neuronal damage. These results support the view that microglial cells are extremely sensitive to changes of the brain microenvironment. Their activation may be related to changes of ion homeostasis in the brain which are not sufficient to trigger neuronal injury. 相似文献
38.
Messer RL Lockwood PE Tseng WY Edwards K Shaw M Caughman GB Lewis JB Wataha JC 《Journal of biomedical materials research. Part B, Applied biomaterials》2005,75(2):257-263
The perennial controversy about the safety of mercury in dental amalgams has adversely affected the availability and the quality of dental care. Chronic Hg(II) blood concentrations above 300 nM are known to alter function of the nervous system and the kidney. However, the effects of blood concentrations of 10 to 75 nM, far more common in the general population, are not clear and mechanisms of any effects are not known. The monocyte is an important potential target of Hg(II) because of its critical role in directing inflammatory and immune responses. In the current study we tested the hypothesis that concentrations of Hg(II) of 10 to 300 nM alter monocyte activity via a redox-dependent mechanism. Mitochondrial activity was used to establish inhibitory concentrations of Hg(II) following 6 to 72 h of exposures to THP1 human monocytic cells. Then subinhibitory concentrations were applied, and total glutathione levels and reactive oxygen species (ROS) were measured. Antioxidants [N-acetyl cysteine, (NAC); Na2SeO3, (Se)] and a pro-oxidant (tert-butylhydroquinone, tBHQ) were used to support the hypothesis that Hg(II) effects were redox-mediated. After 72 h of exposure, 20 microM of Hg(II) inhibited monocytic mitochondrial activity by 50%. NAC mitigated Hg(II)-induced mitochondrial suppression only at concentrations of greater than 10 microM, but Se had few effects on Hg-induced mitochondrial responses. tBHQ significantly enhanced mitochondrial suppression at higher Hg(II) concentrations. Hg(II) concentrations of 75 and 300 nM (0.075 and 0.30 microM, respectively) significantly increased total glutathione levels, and NAC mitigated these increases. Se plus Hg(II) significantly elevated Hg-induced total cellular glutathione levels. Increased ROS levels were not detected in monocytes exposed to mercury. Hg(II) acts in monocytic cells, at least in part, through redox-mediated mechanisms at concentrations below those commonly associated with chronic mercury toxicity, but commonly occurring in the blood of some dental patients. 相似文献
39.
The siderophore iron transporter of Candida albicans (Sit1p/Arn1p) mediates uptake of ferrichrome-type siderophores and is required for epithelial invasion 下载免费PDF全文
Heymann P Gerads M Schaller M Dromer F Winkelmann G Ernst JF 《Infection and immunity》2002,70(9):5246-5255
The human fungal pathogen Candida albicans contains a close homologue of yeast siderophore transporters, designated Sit1p/Arn1p. We have characterized the function of SIT1 in C. albicans by constructing sit1 deletion strains and testing their virulence and ability to utilize a range of siderophores and other iron complexes. sit1 mutant strains are defective in the uptake of ferrichrome-type siderophores including ferricrocin, ferrichrysin, ferrirubin, coprogen, and triacetylfusarinine C. A mutation of FTR1 did not impair the use of these siderophores but did affect the uptake of ferrioxamines E and B, as well as of ferric citrate, indicating that their utilization was independent of Sit1p. Hemin was a source of iron for both sit1 and ftr1 mutants, suggesting a pathway of hemin uptake distinct from that of siderophores and iron salts. Heterologous expression of SIT1 in the yeast Saccharomyces cerevisiae confirmed the function of Sit1p as a transporter for ferrichrome-type siderophores. The sit1 mutant was defective in infection of a reconstituted human epithelium as a model for human oral mucosa, while the SIT1 strain was invasive. In contrast, both sit1 and SIT1 strains were equally virulent in the mouse model of systemic infection. These results suggest that siderophore uptake by Sit1p/Arn1p is required in a specific process of C. albicans infection, namely epithelial invasion and penetration, while in the blood or within organs other sources of iron, including heme, may be used. 相似文献
40.
Lee YJ Hohoff C Domschke K Sand P Kuhlenbäumer G Schirmacher A Freitag CM Meyer J Stöber G Franke P Nöthen MM Fritze J Fimmers R Garritsen HS Stögbauer F Deckert J 《Neuroscience letters》2005,377(1):40-43
Several biochemical and pharmacological studies suggest that the catecholaminergic system involving the norepinephrine transporter (NET) is relevant for the pathogenesis of panic disorder. Three single nucleotide polymorphisms in the promoter or untranslated 5' region of the NET gene were investigated by means of RFLP analysis in a sample of 115 German patients with panic disorder and 115 matched controls. Statistical analysis failed to show association with the overall diagnosis of panic disorder. In the subgroup of patients with panic disorder without agoraphobia, however, two polymorphisms were found to be associated with the disease (G/C (rs2397771): p < 0.05; T/C (rs2242446): p < 0.01). While our data do not support a major function of the NET gene in the development of panic disorder, it may play a role in the subgroup of panic disorder without agoraphobia. 相似文献