全文获取类型
收费全文 | 108328篇 |
免费 | 6562篇 |
国内免费 | 645篇 |
专业分类
耳鼻咽喉 | 1067篇 |
儿科学 | 3489篇 |
妇产科学 | 2462篇 |
基础医学 | 15762篇 |
口腔科学 | 3938篇 |
临床医学 | 9900篇 |
内科学 | 24351篇 |
皮肤病学 | 2727篇 |
神经病学 | 10835篇 |
特种医学 | 2529篇 |
外国民族医学 | 1篇 |
外科学 | 9699篇 |
综合类 | 407篇 |
一般理论 | 48篇 |
预防医学 | 10749篇 |
眼科学 | 1751篇 |
药学 | 7678篇 |
中国医学 | 416篇 |
肿瘤学 | 7726篇 |
出版年
2024年 | 85篇 |
2023年 | 976篇 |
2022年 | 1754篇 |
2021年 | 3711篇 |
2020年 | 2350篇 |
2019年 | 3142篇 |
2018年 | 3563篇 |
2017年 | 2715篇 |
2016年 | 3150篇 |
2015年 | 3478篇 |
2014年 | 4571篇 |
2013年 | 5973篇 |
2012年 | 9043篇 |
2011年 | 9406篇 |
2010年 | 5119篇 |
2009年 | 4336篇 |
2008年 | 7466篇 |
2007年 | 7464篇 |
2006年 | 6878篇 |
2005年 | 6424篇 |
2004年 | 5793篇 |
2003年 | 5145篇 |
2002年 | 4636篇 |
2001年 | 619篇 |
2000年 | 442篇 |
1999年 | 660篇 |
1998年 | 818篇 |
1997年 | 673篇 |
1996年 | 567篇 |
1995年 | 466篇 |
1994年 | 448篇 |
1993年 | 360篇 |
1992年 | 339篇 |
1991年 | 233篇 |
1990年 | 232篇 |
1989年 | 212篇 |
1988年 | 216篇 |
1987年 | 171篇 |
1986年 | 185篇 |
1985年 | 147篇 |
1984年 | 158篇 |
1983年 | 150篇 |
1982年 | 173篇 |
1981年 | 128篇 |
1980年 | 137篇 |
1979年 | 94篇 |
1978年 | 88篇 |
1977年 | 82篇 |
1976年 | 67篇 |
1974年 | 59篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
951.
Francesco Tedesco Maria A. Villa Peter Densen Girolamo Sirchia 《Molecular immunology》1983,20(1):47-51
Structural and functional studies were performed on a dysfunctional C8 molecule present in the serum of two siblings and an unrelated individual. The C8 in these three sera exhibited a pattern of partial immunologic identity with C8 in normal serum but was devoid of functional activity. The C8 was immunoprecipitated from the three sera and from a control serum with an antihuman C8 antiserum and analyzed by SDS-PAGE using highly purified human C8 as a reference. A selective absence of a band of 62,000 mol. wt was observed in the immunoprecipitates from the sera containing dysfunctional C8. Experiments performed with the purified α-γ and γ subunits showed that the hemolytic activity of the C8 deficient sera could be reconstituted by the addition of the β chain but not the α-γ dimer. Binding of the dysfunctional C8 to C was excluded by the following observations: (1) EAC 1–7 treated with the C8 deficient sera and then washed could not be lysed after the addition of the β subunit and C9; and (2) the abnormal molecules did not interfere with the consumption of normal C8 by the soluble complex SC5b-7. 相似文献
952.
1) |
Pediatric neurosurgery is the theory and art of surgical treatment of diseases of the child’s nervous system. 相似文献
953.
Angelo Passerini Liliana Strada Marina Grisoli Maurizio Sberna Maria Grazia Bruzzone 《Child's nervous system》1990,6(1):33-36
The spin-echo procedure is the basic technique in a magnetic resonance (MR) study (the magnetization vector is flipped by 90° onto the ortogonal plane to the main magnetic field). Very soon after the MR procedure was developed, it was pointed out how important it is to achieve the needed contrast with shorter repetition times (TRs) to reduce the imaging time. Recently, fast imaging techniques have been introduced (partial flip angles, short TRs, and the lack of 180° radiofrequency pulses to refocus the spins are their main characteristics; the spins are refocused by the application of a gradient reversal technique). These techniques are particularly needed in pediatric neuroradiology, where the examination time must be as short as possible. At present, partial flip-angle techniques are almost completely replacing the conventional spin-echo procedure, but the variations in flip angle could result in a change in contrast. For these reasons, conventional spin-echo techniques may still be useful in a routine MR study.Presented at the 11th Meeting of the European Society for Paediatric Neurosurgery, Naples 1988 相似文献
954.
Giovina De Rosa Arnerico Testa Maurizio Maurizi Maria Antonietta Satta Claudia Aimoni Alberto Artuso Evelina Silvestri Vittoria Rufini Luigi Troncone 《European journal of nuclear medicine and molecular imaging》1990,17(3-4):179-184
A young woman with a thyroid papillary carcinoma behaving as an autonomously hyperfunctioning nodule is described. Only 17 similar patients have been seen in the past 25 years. It is emphasized that hyperthyroidism does not exclude malignant disease in hot nodules. This possibility suggests that all thyroid nodules, either cold or hot, require careful management. Therefore, in at risk cases, surgery could be the most useful treatment. 相似文献
955.
Richard Bost MD Jean Hostein MD Maria Valenti Bruno Bonaz MD Nicole Payen Henri Faure Jacques Fournet MD 《Digestive diseases and sciences》1990,35(2):193-199
A quantitatively and/or qualitatively abnormal duodenogastric reflux (DGR) could be involved in the pathogenesis of nonulcer dyspepsia (NUD). The aims of this prospective study were to look for (1) a pathological DGR profile during fasting and (2) an eventual correlation between DGR profile and clinical symptoms. Twenty-six NUD patients were investigated. Seven other operated patients with a surgical procedure facilitating DGR episodes and 27 healthy volunteers served as control groups. A clinical score was determined for each patient from a standardized questionnaire. Gastric aspiration was performed for 6 hr in fasting subjects. The aspirates were pooled into 17 samples. In each sample the concentration and the output of total bile acids was determined. If the concentration was larger than 30 mol/liter in pooled samples, the concentrations of free bile acids and the distribution of the conjugated bile acids was determined. The percentage of aliquots with a total bile acid concentration larger than 50 mol/liter (without upper limit), and the percentage with a concentration larger than 2500 mol/liter was also obtained. No significant difference was demonstrated between the healthy volunteers and NUD patients, whatever the parameter considered. However, there was a significant increase in each of the quantitative parameters for the group of operated patients in comparison with the NUD patient group. No significant correlation was found between the clinical score and the DGR profile in NUD patients. Apparently, DGR episodes do not play a primary role in the pathogenesis of NUD.Part of this work was presented at the 4th European Symposium on Gastrointestinal Motility, Krakow, Poland. September 22–24, 1988.Hepatogastroenterology, 35:178, 1988 (abstract). 相似文献
956.
Edward K. Kasper 《The International Journal of Cardiac Imaging》1990,6(Z1):51-52
AbstractsNew form of cardiomyopathy 相似文献957.
Reduction of cell proliferative activities of gastric stump adenomatous hyperplasias after bile reflux diversion in rats 总被引:4,自引:1,他引:3
Imai Toshio; Kobayasi Shoiti; Rodrigues Maria Aparecida Marchesan; Camargo Joao Lauro Viana de; Ogawa Kumiko; Iwata Hitoshi; Tatematsu Masae 《Carcinogenesis》1993,14(9):1765-1769
Previously we reported the majority of lesions induced by bilereflux, in the absence of chemical carcinogens, in the rat remnantstomach to consist primarily of gastric type and secondarilyof intestinal type cells, and that they are reversible afterdiversion of bile reflux. The present study was designed toevaluate changes in proliferative activities in cells of eachtype under these conditions. The frequency of adenomatous hyperplasia(AH) induced in the gastric stump mucosa by duodenal contentreflux after Billroth II partial gastrectomy (BII) increaseduntil the 54th week of the experiment. Roux-en-Y (RY) surgicalprocedure which prevents duodenal reflux performed at the 24thor 36th week after BII led to a decrease in AH. Cell contentof the lesions was analyzed using routine H&E staining,immunohistochemical staining for pepsinogen isoenzyme 1 andhistochemical procedures for mucins (paradoxical concanavalinA, galactose oxidase Schiff and sialidase galactose oxidaseSchiff reactions) and proliferation in each compartment evaluatedby an immunohistochemical method using bromodeoxyuridine (BrdU)and a monoclonal antibody against BrdU. At the 54th week thenumber of BrdU-labeled cells per normal pyloric column was significantly(P < 0.05) increased to 10.63/pit after the BII operation,while it diminished to 5.23/pit after RY diversion, this beingthe same level as with the RY procedure alone. AH maintaineda high rate of BrdU incorporation at 12.7% after BII operation,which was also significantly reduced (P < 0.01) to 7.0% bythe RY surgery. The intestinal type cell showed highest (22.2%),the surface mucous type cell showed the next (16.5%) and thepyloric gland type cell showed lowest (5.2%) BrdU labeling indicesafter BII operation. All the cell types in AH showed similarproportional decreases in BrdU incorporation after RY diversion.Thus surgical intervention reverses the cell proliferation causedby bile reflux in the gastric stump. 相似文献
958.
Maria Dengler-Harles John M. Wild Michael D. Cole Eamon C. O'Neill 《Albrecht von Graefes Archiv fur klinische und experimentelle Ophthalmologie》1993,231(6):337-343
The various stimulus parameters offered by two standard automated projection perimeters [Humphrey Field Analyser 630 (HFA) and Octopus 2011, namely, stimulus size and location and the interaction of adaptation level and stimulus duration, were compared in a sample of 20 patients attending a glaucoma clinic using the visual field indices mean defect (MD), loss variance (LV), short-term fluctuation (SF) and corrected loss variance (CLV). LV and SF were greater with Octopus program 32 compared with Octopus program G1 (P < 0.02). No difference in the indices was found between stimulus sizes I and III for HFA program 30-2. MD was greater for program 30-2 compared with program 32 (P < 0.002) when expressed in terms of log (L/L) whereas LV (P < 0.02) and SF (P < 0.02) were greater for program 32. All differences were considered to be negligible in the clinical sense. 相似文献
959.
Stella M. Pezzotto Ricardo Mahuad Maria L. Bay Julio C. Morini Leonor Poletto 《Cancer causes & control : CCC》1993,4(3):231-237
A high mortality rate for lung cancer (62.7 per 100,000) is found in Rosario, Argentina. To investigate the reasons for this high rate, a case-control study was carried out among 215 male cases with histologically confirmed lung cancer and 433 hospitalized controls for conditions unrelated to tobacco consumption. Odds ratios (OR) of squamous cell (SQ), adenocarcinoma (AD), and small cell (SM) carcinoma of the lung associated with different characteristics of the smoking habit were quantified. Ninety-eight percent of the cases had smoked regularly. Smokers were significantly younger at diagnosis than ex-smokers (P<0.0001), a pattern consistent for all cell types. The ORs for the heaviest cf the lowest consumption categories were 15.3 for SQ, 11.6 for AD, and 11.6 for all lung cancer (P<0.0001). Risks associated with the use of unfiltered cigarettes were three to five times higher than those for filtered cigarettes, depending on cell types. For ex-smokers, risks after 10 years of nonsmoking were about 12 times lower than those of current smokers (P<0.001). To halt further increases in lung cancer, preventive measures in Argentina should be directed primarily towards smoking control.Ms Pezzotto and Drs Bay, Morini, and Poletto are with the Institute of Immunology, School of Medicine, National University of Rosario, Argentina. Dr Mahuad is with Hospital Italiano Rosario, Argentina. Address correspondence to Ms Pezzotto, Inst. Inmunologia, Facultad de Medicina, Santa Fe 3100, 2000 Rosario, Argentina. 相似文献
960.
|