全文获取类型
收费全文 | 1936篇 |
免费 | 150篇 |
国内免费 | 8篇 |
专业分类
耳鼻咽喉 | 10篇 |
儿科学 | 86篇 |
妇产科学 | 43篇 |
基础医学 | 215篇 |
口腔科学 | 59篇 |
临床医学 | 237篇 |
内科学 | 463篇 |
皮肤病学 | 47篇 |
神经病学 | 149篇 |
特种医学 | 264篇 |
外科学 | 159篇 |
综合类 | 29篇 |
一般理论 | 1篇 |
预防医学 | 149篇 |
眼科学 | 18篇 |
药学 | 86篇 |
中国医学 | 8篇 |
肿瘤学 | 71篇 |
出版年
2023年 | 20篇 |
2022年 | 18篇 |
2021年 | 47篇 |
2020年 | 20篇 |
2019年 | 29篇 |
2018年 | 67篇 |
2017年 | 33篇 |
2016年 | 38篇 |
2015年 | 42篇 |
2014年 | 57篇 |
2013年 | 67篇 |
2012年 | 80篇 |
2011年 | 81篇 |
2010年 | 74篇 |
2009年 | 76篇 |
2008年 | 91篇 |
2007年 | 71篇 |
2006年 | 77篇 |
2005年 | 52篇 |
2004年 | 50篇 |
2003年 | 64篇 |
2002年 | 50篇 |
2001年 | 55篇 |
2000年 | 40篇 |
1999年 | 38篇 |
1998年 | 57篇 |
1997年 | 61篇 |
1996年 | 69篇 |
1995年 | 55篇 |
1994年 | 50篇 |
1993年 | 50篇 |
1992年 | 26篇 |
1991年 | 21篇 |
1990年 | 25篇 |
1989年 | 47篇 |
1988年 | 38篇 |
1987年 | 39篇 |
1986年 | 44篇 |
1985年 | 35篇 |
1984年 | 23篇 |
1983年 | 12篇 |
1982年 | 22篇 |
1981年 | 14篇 |
1980年 | 9篇 |
1979年 | 7篇 |
1978年 | 5篇 |
1977年 | 12篇 |
1976年 | 11篇 |
1975年 | 13篇 |
1969年 | 4篇 |
排序方式: 共有2094条查询结果,搜索用时 62 毫秒
51.
We have explored the polymorphism of the glycophorin system in the human erythrocyte membrane using the immunoblotting techniques and examining 52 individuals selected without prior bias as to their serologic state and ten documented serologic variants of M, N, S, s blood group system. Polyclonal antisera to alpha glycophorin and to alpha glycophorin CNBr carboxyl terminal fragment C (residues 82-131) and M and N specific monoclonal antibodies (MoAbs) were used. The first two reagents detect specific regions of the alpha glycophorin molecule and all electrophoretically resolved species of glycophorins immunologically related to alpha and delta glycophorins (delta glycophorin, [alpha-delta] hybrids and other glycophorins with an alteration in the carboxyl terminal segment); the M and N MoAbs identified the glycophorin species containing or lacking the M or N determinant in the amino terminal octapeptide structures. We find that immunoblotting confirmed in all cases the serologically determined phenotype; we also find that polymorphic forms of the glycophorin system are relatively infrequent; immunoblotting, independent from serologic testing, was capable of detecting five mutants, two most likely S-s-U-phenotypes; a new glycophorin species was detected in normal red cells with both antiglycophorin and antipeptide C sera, which is not evident with MoAbs; immunoblots of known glycophorin variants (En(a-), U-, Mg, Mi I, II, III, V, and Sta) confirmed but also extended our knowledge of the abnormal glycophorins involved; and the He+ and Wrb(-) cells showed normal patterns. 相似文献
52.
Cytogenetic and histologic correlations in malignant lymphoma 总被引:9,自引:0,他引:9
Koduru PR; Filippa DA; Richardson ME; Jhanwar SC; Chaganti SR; Koziner B; Clarkson BD; Lieberman PH; Chaganti RS 《Blood》1987,69(1):97-102
Although a number of studies have indicated correlations between histologic subtypes of tumors and certain nonrandom chromosome changes, cytogenetic studies of lymphoma are in an early stage compared to those of leukemia. No comprehensive analysis of available data has so far been attempted in the literature either. Here we present an analysis of chromosome changes and their correlation with subtypes of lymphoma studied by conventional histology and cell surface markers, as observed in two sets of data: a group of 65 karyotypically abnormal tumors sequentially ascertained and studied by us during the period January 1, 1984 to April 30, 1985, and a larger data set derived by combining our data with those from two published series from the University of Minnesota that are comparable to our data. These combined data, which comprise the largest data set on the cytogenetics of lymphomas assembled so far, enabled a comprehensive analysis of correlation between chromosome change and tumor histology and the patterns of chromosome instability in these tumors. We found several significant associations, some previously described and others now recognized, between nonrandom chromosome gains, breaks, translocations, and deletions and histologic subtypes of tumors that characterize lymphomas. The data indicate that finding of chromosome breaks at certain sites (eg, 8q24, 14q32, 18q21) is of diagnostic value in dealing with cases of unusual lymphoma. Furthermore, nonrandom chromosome breakage exhibited three distinct patterns that reflected three levels of etiologically relevant genetic change. 相似文献
53.
Minasian LM; Szatrowski TP; Rosenblum M; Steffens T; Morrison ME; Chapman PB; Williams L; Nathan CF; Houghton AN 《Blood》1994,83(1):56-64
Hemorrhagic tumor necrosis is an inflammatory event that leads to selective destruction of malignant tissues, with both potentially toxic and beneficial consequences. A pilot clinical trial was undertaken combining tumor necrosis factor-alpha (TNF-alpha) with the monoclonal antibody R24 (MoAb R24) against GD3 ganglioside in patients with metastatic melanoma. Patients received MoAb R24 to recruit leukocytes to the tumor followed by low doses of recombinant TNF-alpha to activate leukocytes. Eight patients were treated and seven patients had mild toxicity. One patient with extensive metastatic melanoma developed tumor lysis syndrome within hours after treatment with almost complete necrosis of bulky tumors in multiple visceral sites. To our knowledge, this is the first documented case of hemorrhagic tumor necrosis in a patient with metastatic cancer in multiple visceral sites. 相似文献
54.
González Hernández E Cabadés O'Callaghan A Cebrián Doménech J López Merino V Sanjuán Mañez R Echánove Errazti I Valencia Martín J Bertomeu Martínez V;Investigadores del estudio PRIMVAC 《Revista espa?ola de cardiología》2004,57(1):12-19
INTRODUCTION AND OBJECTIVES: Some authors have described seasonal variations in the incidence of acute myocardial infarction. The aim of this study was to determine the existence of seasonal rhythms in admissions for acute myocardial infarction to coronary care units, and in mortality, and to analyze the influence of age on environmental factors. PATIENTS AND METHOD: The study included a total of 8400 consecutive patients with acute myocardial infarction admitted to 12 coronary care units in the PRIMVAC registry from January 1995 to December 1999. Seasonal rhythms were analyzed with the time series method and the Cosinor regression equation. The influence of age was analyzed with the chi 2 test. RESULTS: The total number of admissions increased in winter and decreased in summer. The highest peak (acrophase) occurred in winter, with 2183 cases (r2=0.91), specifically in February, with 742 cases (r2=0.66). The age of the patients conditioned seasonal variations (P=.006), and the influence was statistically significant for patients over 65 years of age. Changes in mortality with time did not reach statistical significance. CONCLUSIONS: A seasonal rhythm in admissions for acute myocardial infarction was found, with an increase in winter and a decrease in summer. Age conditioned the effect of environmental factors on acute myocardial infarction, and patients aged 65 years or older were more sensitive to mechanisms that led to increases in admissions in winter. 相似文献
55.
Stacy Schantz Wilkins PhD Rebecca J. Melrose PhD Katherine S. Hall PhD Erin Blanchard MS Steven C. Castle MD Teresa Kopp PT MBA Leslie I. Katzel MD PhD Alice Holder MHS PT Neil Alexander MD Michelle K.S. McDonald BA OT Arti Tayade MD CMD HMDC Daniel E. Forman MD Lauren M. Abbate MD PhD Rebekah Harris PT DPT PhDc Willy M. Valencia MD Miriam C. Morey PhD Cathy C. Lee MD 《Journal of the American Geriatrics Society》2021,69(4):1045-1050
56.
57.
Factor VIII coagulant protein (VIII:C) functions as a critical cofactor with factor IXa, calcium ions, and phospholipid during the activation of factor X. In the course of this reaction, the activity of VIII:C is first increased and then is destroyed by one or more serine proteases that are part of the coagulation sequence. In this study, we have investigated the influence of platelets on the inactivation of VIII:C by plasmin. Platelets were separated from plasma proteins in the presence of granule release inhibitors and were incubated with plasmin and isolated VIII:C or the complex of purified VIII:C/von Willebrand factor (vWF); VIII:C activity and antigen levels were assessed over time. In the presence of platelets, the isolated VIII:C showed an initial increase in VIII:C activity that was not present when platelets were absent, and the VIII:C/vWF showed an increase in VIII:C activity over that seen when platelets were absent. In addition, platelets stabilized VIII:C activity over a one-hour time course when compared with buffer. The VIII:C antigen did not increase and decreased slowly whether platelets were present or absent. Preincubating the platelets with ristocetin, collagen, or plasmin did not alter the results, and experiments using platelets from a patient with severe von Willebrand's disease also showed a pattern similar to that seen with normal platelets. Experiments using fixed platelets or phospholipid vesicles showed that they did not support the activation reaction or delay the inactivation reaction. These studies demonstrate that platelets modulate the activation and inactivation of VIII:C by plasmin, apparently by a mechanism that is independent of the platelet release reaction. 相似文献
58.
59.
Background: The assessment of physical activity intensity and duration is essential for understanding group activity patterns.Methods: The present study evaluated the validity of measurement of total energy expenditure (TEE) and physical activity level (PAL) using a categorized physical activity diary. In 29 young healthy men, aged 18–27 years, with body mass index range 21–43 kg m?2, TEE using doubly-labelled water (DLW), resting metabolic rate (RMR) by indirect calorimetry, physical activity level (PAL defined as TEE/RMR) and activity pattern, timing and level from 7-day physical activity diaries were determined.Results: TEE by DLW and estimated by activity diary were correlated (r?=?0.61, p?=?0.005). The mean underestimation of TEE by the activity diary compared with the DLW method was 2.50?±?0.72 MJ day?1. Sedentary (lying, sitting and standing) time averaged 18 h day?1 and was negatively correlated with PAL (r?=??0.44, p?=?0.018) whilst time spent in light intensity activity (5 h day?1) was positively correlated (r?=?0.51, p?=?0.005).Conclusions: It is concluded that the categorized physical activity diary measured TEE with limited accuracy but presents an inexpensive, convenient method of discriminating individual and group physical activity patterns. 相似文献