全文获取类型
收费全文 | 2393681篇 |
免费 | 187062篇 |
国内免费 | 9783篇 |
专业分类
耳鼻咽喉 | 30651篇 |
儿科学 | 78227篇 |
妇产科学 | 65465篇 |
基础医学 | 339572篇 |
口腔科学 | 65934篇 |
临床医学 | 225439篇 |
内科学 | 474593篇 |
皮肤病学 | 52870篇 |
神经病学 | 198691篇 |
特种医学 | 92351篇 |
外国民族医学 | 622篇 |
外科学 | 352543篇 |
综合类 | 55315篇 |
现状与发展 | 3篇 |
一般理论 | 838篇 |
预防医学 | 200701篇 |
眼科学 | 51865篇 |
药学 | 172236篇 |
11篇 | |
中国医学 | 4914篇 |
肿瘤学 | 127685篇 |
出版年
2018年 | 26452篇 |
2017年 | 20387篇 |
2016年 | 23286篇 |
2015年 | 26363篇 |
2014年 | 36594篇 |
2013年 | 56024篇 |
2012年 | 72269篇 |
2011年 | 77319篇 |
2010年 | 46583篇 |
2009年 | 44305篇 |
2008年 | 71296篇 |
2007年 | 75612篇 |
2006年 | 76917篇 |
2005年 | 74307篇 |
2004年 | 70863篇 |
2003年 | 68193篇 |
2002年 | 65413篇 |
2001年 | 109657篇 |
2000年 | 112738篇 |
1999年 | 94629篇 |
1998年 | 28220篇 |
1997年 | 25368篇 |
1996年 | 25959篇 |
1995年 | 25558篇 |
1994年 | 23932篇 |
1993年 | 22435篇 |
1992年 | 77394篇 |
1991年 | 75553篇 |
1990年 | 72907篇 |
1989年 | 69289篇 |
1988年 | 64388篇 |
1987年 | 63122篇 |
1986年 | 59953篇 |
1985年 | 57630篇 |
1984年 | 43922篇 |
1983年 | 37031篇 |
1982年 | 22915篇 |
1981年 | 20470篇 |
1980年 | 19172篇 |
1979年 | 39720篇 |
1978年 | 28776篇 |
1977年 | 23904篇 |
1976年 | 22748篇 |
1975年 | 23482篇 |
1974年 | 28126篇 |
1973年 | 27185篇 |
1972年 | 25121篇 |
1971年 | 23276篇 |
1970年 | 21395篇 |
1969年 | 19814篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
The purpose of this study was to evaluate a new fluorescence polarization immunoassay, TDx, for digitoxin by comparing the results of this assay with those of a radioimmunoassay (RIA). Thirty-three serum samples were obtained from 15 patients during, and for 4 weeks after, a 4-week course of digitoxin therapy. Each sample was separated by centrifugation, coded, and frozen until analysis. At the time of analysis, each sample was divided and analyzed simultaneously by TDx and RIA. Nine samples yielded results less than 2 ng/ml (limit of assay sensitivity) by one or both methods and were excluded from further data analysis. Linear regression analysis of the results of the remaining 24 paired samples (x = TDx, y = RIA) revealed a strong correlation coefficient of r2 = 0.95, slope = 0.95, and a y intercept of -0.99 (y = -0.99 + 0.95x). Additionally, the TDx results were lower than the RIA values in only five of 33 paired samples; and these occurred in four patients who had a significantly lower mean estimated creatinine clearance than that of the other 11 patients (39.0 +/- 9.1 ml/min/1.73 m2 vs. 63.3 +/- 11.8 ml/min/1.73 m2, p less than 0.01). The TDx system is a comparable alternative to the RIA method, but differences in specificity and sensitivity may exist and should be evaluated more thoroughly. 相似文献
992.
Summary The left recurrent laryngeal nerves from five horses with sub-clinical neuropathy were examined by light and electron microscopy in a study designed to examine accumulation of axonal organelles at paranodal and internodal locations. Transverse sections of the nerve showed scattered fibres with split myelin sheaths and axonal accumulation of organelles. On longitudinal sections these collections were seen to result from an axonal outpouching in which dense lamellar bodies and mitochondria had accumulated. These paranodal collections, which could be found on both sides of the node, were often associated with infoldings of the terminal loops of myelin and with occasional paranodal demyelination. The fact that many of the organelles in the outpouches were lysosomal in nature was confirmed by their positive staining for cathepsin D activity. Longitudinal sections demonstrated a number of axons which were swollen over a long distance and which contained focal accumulations of similar organelles. In places, however, there was a clear separation between these organelles and the cytoskeletal proteins. In each case these swollen axons were surrounded by Schwann cell nuclei and their processes, forming well-ordered onion bulbs. The possibility that these two types of changes, i.e. the paranodal accumulations and the axonal swellings could result from a disturbance in axonal transport in this distal axonopathy is discussed. 相似文献
993.
Trends in analgesic self-poisoning in West-Fife, 1971-1985 总被引:1,自引:0,他引:1
J J McMurray D B Northridge V A Abernethy A A Lawson 《The Quarterly journal of medicine》1987,65(246):835-843
All admissions for analgesic self-poisoning to a district poisons unit over a 15-year period have been reviewed. During this time overdose with analgesic drugs increased to represent almost half of all admissions for self-poisoning. The types of analgesics taken in overdose also changed significantly during the period of this review. Aspirin and Distalgesic poisoning declined in incidence and more cases of self-poisoning by paracetamol and non-steroidal anti-inflammatory agents were seen. The impact of these changes on the medical management and outcome of deliberate self-poisoning is analysed. The reasons behind the trends described in this paper are assessed and their implications for future prevention and treatment are discussed. 相似文献
994.
Thomas J Birk Rodger D MacArthur Lynn M Lipton Sheldon D Levine 《The Journal of the Association of Nurses in AIDS Care》2002,13(6):20-24
The purpose of this study was to determine whether blood lipid and lipoprotein concentrations varied in 5 men with advanced HIV-1 infection after 12 months of aerobic exercise training. Prior to exercise, the mean baseline cholesterol and high-density lipoprotein cholesterol (HDL-C) serum concentration were each lower, and mean baseline triglyceride concentration was higher compared to a healthy population norm. Consistent exercise training for 12 months failed to significantly (p > .05) alter cholesterol or HDL-C. Triglyceride concentration was significantly (p < .05) elevated above baseline (63 mg/dL) regardless of exercise compliance. The results suggest that long-term exercise training cannot correct lipid profile abnormality, particularly hypertriglyceridemia, common to individuals with advanced HIV-1 infection. 相似文献
995.
Teenage pregnancy is a well-documented problem in the United States, with approximately 890,000 teenage pregnancies occurring each year. Although teen pregnancy rates have declined since 1991, rates remain higher than the mid-1970s and are fourfold those of European countries. Substantial morbidity and social problems result from these pregnancies, affecting the mother, her children, other family members, and society. Multiple educational approaches have been used, with few demonstrating significant reductions in teen pregnancy. School-based programs have been diverse and multifaceted. Recently, programs with a comprehensive approach have shown potential for success. In this article, characteristics and elements of promising school-based programs are identified and discussed. It is imperative that school nurses play an active role in developing and implementing prevention programs that incorporate rigorous evaluation. As health educators, school nurses are in a prime position to implement and evaluate the effectiveness of teen pregnancy prevention programs. 相似文献
996.
997.
998.
Changing attentional demands in left hemispatial neglect. 总被引:1,自引:0,他引:1
R F Kaplan M Verfaellie M E Meadows L R Caplan M S Pessin L D DeWitt 《Archives of neurology》1991,48(12):1263-1266
Seven variations of a letter cancellation test were used to examine how varying attentional demands affect hemispatial neglect in patients with right hemisphere lesions. While the 14 targets always remained in the same location, the number of distractors (zero, nine, 28, or 82) as well as their complexity (one letter or nine different letters) were varied. The percentage of targets canceled in the left hemispace was linearly related to the number of distractors. There were no differences between the complexity conditions. In a second study, the same 14 targets were presented but the distractors (zero, 14, or 41) were all placed on the right. Increasing the number of distractors on the right increased neglect on both sides of the space. Taken together, these results suggest that, while the limited attentional resources of the left hemisphere are biased toward the right hemispace, the absence of contralateral attentional demands allows these resources to be directed ipsilaterally. 相似文献
999.
1000.