全文获取类型
收费全文 | 10161篇 |
免费 | 573篇 |
国内免费 | 33篇 |
专业分类
耳鼻咽喉 | 250篇 |
儿科学 | 334篇 |
妇产科学 | 134篇 |
基础医学 | 1533篇 |
口腔科学 | 328篇 |
临床医学 | 1006篇 |
内科学 | 1787篇 |
皮肤病学 | 226篇 |
神经病学 | 802篇 |
特种医学 | 484篇 |
外科学 | 1467篇 |
综合类 | 97篇 |
一般理论 | 9篇 |
预防医学 | 607篇 |
眼科学 | 396篇 |
药学 | 718篇 |
中国医学 | 20篇 |
肿瘤学 | 569篇 |
出版年
2022年 | 57篇 |
2021年 | 123篇 |
2020年 | 82篇 |
2019年 | 132篇 |
2018年 | 159篇 |
2017年 | 142篇 |
2016年 | 169篇 |
2015年 | 188篇 |
2014年 | 220篇 |
2013年 | 335篇 |
2012年 | 403篇 |
2011年 | 472篇 |
2010年 | 274篇 |
2009年 | 237篇 |
2008年 | 427篇 |
2007年 | 456篇 |
2006年 | 461篇 |
2005年 | 445篇 |
2004年 | 440篇 |
2003年 | 412篇 |
2002年 | 324篇 |
2001年 | 424篇 |
2000年 | 376篇 |
1999年 | 328篇 |
1998年 | 154篇 |
1997年 | 119篇 |
1996年 | 122篇 |
1995年 | 95篇 |
1994年 | 92篇 |
1993年 | 57篇 |
1992年 | 178篇 |
1991年 | 163篇 |
1990年 | 174篇 |
1989年 | 163篇 |
1988年 | 139篇 |
1987年 | 129篇 |
1986年 | 115篇 |
1985年 | 119篇 |
1984年 | 86篇 |
1983年 | 81篇 |
1982年 | 56篇 |
1980年 | 53篇 |
1979年 | 86篇 |
1978年 | 71篇 |
1977年 | 83篇 |
1975年 | 58篇 |
1974年 | 58篇 |
1973年 | 56篇 |
1972年 | 81篇 |
1938年 | 54篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
Importance of thiols in the reductive binding of 2-nitroimidazoles to macromolecules 总被引:1,自引:0,他引:1
Reductive activation of 2-nitroimidazoles in the presence of bovine serum albumin (BSA) led to binding of the nitroheterocycles to the protein. The binding was most efficient to BSA in which protein disulfides had been reduced to thiol groups. Protein thiols were at least twenty times more efficient than other protein, RNA or DNA nucleophiles in binding the reductively-activated nitroheterocycles. This result is of practical importance in the development of immunoassays for 2-nitroimidazoles as hypoxia markers in normal and tumor tissue. 相似文献
62.
A E Koch 《The Journal of rheumatology》1988,15(2):362-365
A woman with rheumatoid arthritis who underwent total knee arthroplasty is described. The implant became infected with Staphylococcus epidermidis and she received a prolonged course of postoperative antistaphylococcal antibiotics. Four months postoperatively she developed a calf ulcer that grew Pseudomonas aeruginosa and required further antibiotic therapy. One year later she presented with a painful, swollen knee with radiographic findings suggesting loosening of the prosthetic knee implant. Arthrocentesis cultures grew Candida albicans. She was treated with arthrodesis, amphotericin B, 5-fluorocytosine, and ketoconazole and remains free of infection 21 months after removal of the prosthesis. The clinical course of 6 other cases of Candida prosthetic joint infections is reviewed. 相似文献
63.
K. Mörike M. Koch Peter Fritz Wolfgang Urban Michel Eichelbaum 《Archives of toxicology》1996,70(5):300-305
In the pathogenesis of isoniazid-induced hepatic injury, cytochrome P450-dependent metabolic activation of the metabolite,
acetylhydrazine (AcHz), is the crucial step. Exhalation of [14C]-carbon dioxide has previously been used to quantify indirectly this pathway. In contrast, according to the current concept
of AcHz bioactivation, molecular nitrogen is produced directly, but has not yet been identified. Here, we measured [15N]-nitrogen and 14CO2 exhalation, after the administration of [15N2]-[14C]-AcHz, in rats. Laser magnetic resonance (LMR) spectroscopy, a new sensitive and specific technique for the measurement
of 15N and 14N in gas samples, was used. To demonstrate the involvement of cytochrome P450, rats were treated with phenobarbital (PB) or
PB + cobalt(II) chloride (CoCl2) (n=3 in each group). Time-dependent 15N2 exhalation differed significantly between treatment groups (p<0.001). At 240 min, cumulative exhalation of 15N was 1.92±0.43% (mean±SE) of the dose in the control group, 2.53±0.23% in the PB group, and 1.00±0.15% in the PB+CoCl2 group (p<0.05 compared to controls, p<0.01 compared to PB). Cumulative exhalation of 14CO2 in 24 h ranged from 15.1 to 21.9%, with no significant difference between treatment groups. In conclusion, N2 is a metabolite of AcHz. N2 formation reflects the cytochrome P450-mediated activation of AcHz and can be used as an index of this pathway. Generally,
LMR spectroscopy is valuable for monitoring any N2-liberating process in vivo.
Received: 14 March 1995/Accepted: 15 August 1995 相似文献
64.
We report 11 patients seen between 1991 and 1994 with oral lichenoid lesion(OLL). In 10 cases, there was contact with dental amalgam fillings, and in patient no. 10 with both amalgam restorations and a gold crown. The last patient had, in addition to her OLL, lichen planus of the skin and genital mucosa. In 5 cases, combined sensitization to mercury and other metal salts, particularly gold sodium thiosulfate (GST) and palladium chloride (PDC), was observed. In 10 patients, the lesions considerably improved or totally cleared within 1 to 9 months of replacement of restoration materials. Histological examination of biopsies from the test sites of amalgam, mercuric chloride, GST and PDC, taken 10 or 17 days, after application of patch tests, showed lichenoid changes in 7 patients with at least 1 of the allergens. At least 2 patients had inflammatory lesions of the oral mucosa related to both amalgam and gold restorations, combined sensitization to inorganic and organic mercury derivatives. GST and, in 1 case, PDC, a "dental restoration metal intolerance syndrome" is proposed. 相似文献
65.
Aspirin has antisecretory and ulcerogenic properties in the gastrointestinal tract. The aim of this study was to determine the effects of acetylsalicylic acid (ASA) on the electrical and mechanical activity of the ileum in anesthetized New Zealand White rabbits. Ileal electromechanical activity was recorded from serosal electrodes and a miniature intraluminal balloon. Thirty minutes after injection of ASA (30, 60 and 100 mg/kg intravenous) significant and dose-dependent increases in the percentage of slow waves with action potentials were observed when compared with saline-injected animals. The onset of action potentials correlated with phasic increases in intraluminal pressure, indicating the onset of circular muscle contractions. Injection of 15 mg/kg ASA, sodium salicylate (100 mg/kg intravenous) or saline had no effect on baseline action potential activity. Prostaglandin E
2 (PGE
2)(5 and 10 g/kg intravenous) significantly increased slow-wave frequency and decreased ASA-induced action potential activity. This study demonstrates that (1) ASA, but not sodium salicylate, stimulates phasic ileal action potential and contractile activity and (2) in ASA-treated animals, PGE
2
produces differential effects on in vivoslow-wave frequency and action potential activity. 相似文献
66.
Koch KL 《Practical gastroenterology》1989,13(4):37, 41-37, 44
Myoelectrical activity recorded simultaneously from mucosal, serosal, and cutaneous electrodes has confirmed that the 3-cpm signal from such electrodes reflects gastric slow-wave activity. Now, the observation that patients with unexplained nausea and vomiting may have very rapid slow-wave frequencies (tachygastrias) and very slow, slow-wave frequencies (bradygastrias) suggests that electrogastrography, a reliable and noninvasive technique, may be useful in the diagnosis and management of patients with upper abdominal symptoms and gastroparesis. 相似文献
67.
J. Angst M. Vollrath R. Koch A. Dobler-Mikola 《European archives of psychiatry and clinical neuroscience》1989,238(5-6):285-293
Summary This study describes sleep behaviour and insomnia in a representative cohort of a Swiss population. Interviews were carried out prospectively from age 20–21 to 27–28 years, starting with 292 males and 299 females. Females usually go to bed earlier and sleep 30 min longer than males. Taking into account length and periodicity of insomnia we can distinguish occasional insomnia (OI), repeated brief insomnia (RBI), and continued insomnia (CI), defined by operational criteria. The prevalence of sleep problems is stable from age 21–28, at 36%–40%. CI (prevalence 8%–10%) and RBI (13%–19%) are both medical problems in terms of treatment by professionals (10%–17%) or self-medication (7%–12%). The majority of insomniacs cope with sleep problems in various other ways. Frequency and patterns of symptoms of insomnia are described.The authors thank P. J. Clayton, M.D., University of Minnesota, Minneapolis, for advice and critical suggestions and for the coining of the terms repeated brief insomnia and continued insomnia.Project supported by grant 3.948.0.85 from the Swiss National Science Foundation.Parts of this article were presented on the occasion of the inauguration ceremony of the Department of Psychiatry of the University of Mainz on April 2 and 3, 1987 相似文献
68.
Five iridoids have been isolated from the aerial parts of SCAEVOLA RACEMIGERA D?niker, namely, loganin, loganic acid, sylvestroside III, cantleyoside, and scaevoloside. This latter is a novel compound whose structure 1 has been elucidated on the basis of its spectral data, mainly (1)H- and (13)C-NMR. 相似文献
69.
With the histochemical immunofluorescence technique were demonstrated the insulin and glucagon in the transplantated isolated Langerhans' islets in the liver at diabetic rats and dogs. Further on were tested the diabetic metabolic level with aid of clinico-chemical methods during the period of investigation (blood glucose, serum insulin, glucose tolerance test). It was found that after transplantation, 1 year by the rats and more than 8 weeks by the dogs, is existing a normoglycemic level. In the transplanted islets were seen a good immunofluorescence of insulin in the B cells and the glucagon in the A cells in all investigated stages. 相似文献
70.
We have used an approximately 8.7-Mb BAC contig of Arabidopsis thaliana Chromosome 4 to trace homeologous chromosome regions in 21 species of the family Brassicaceae. Homeologs of this segment could be identified in all tested species. Painting of pachytene chromosomes of Calepina, Conringia, and Sisymbrium species (2n = 14, 16), traditionally placed in tribe Brassiceae, showed one homeologous copy of the Arabidopsis contig, while the remaining taxa of the tribe (2n = 14-30) revealed three, and three Brassica species (2n = 34, 36, and 38) and Erucastrum gallicum (2n = 30) had six copies corresponding to the 8.7-Mb segment. The multiple homeologous copies corresponded structurally to the Arabidopsis segment or were rearranged by inversions and translocations within the diploidized genomes. These chromosome rearrangements accompanied by chromosome fusions/fissions led to the present-day chromosome number variation within the Brassiceae. Phylogenetic relationships based on the chloroplast 5'-trnL (UAA)-trnF(GAA) region and estimated divergence times based on sequence data of the chalcone synthase gene are congruent with comparative painting data and place Calepina, Conringia, and Sisymbrium outside the clade of Brassiceae species with triplicated genomes. Most likely, species containing three or six copy pairs descended from a common hexaploid ancestor with basic genomes similar to that of Arabidopsis. The presumed hexaploidization event occurred after the Arabidopsis-Brassiceae split, between 7.9 and 14.6 Mya. 相似文献