全文获取类型
收费全文 | 214188篇 |
免费 | 3441篇 |
国内免费 | 225篇 |
专业分类
耳鼻咽喉 | 1614篇 |
儿科学 | 7760篇 |
妇产科学 | 3965篇 |
基础医学 | 20422篇 |
口腔科学 | 2811篇 |
临床医学 | 15722篇 |
内科学 | 39322篇 |
皮肤病学 | 1432篇 |
神经病学 | 18680篇 |
特种医学 | 10239篇 |
外国民族医学 | 6篇 |
外科学 | 35863篇 |
综合类 | 3229篇 |
现状与发展 | 3篇 |
一般理论 | 34篇 |
预防医学 | 20710篇 |
眼科学 | 4173篇 |
药学 | 12506篇 |
1篇 | |
中国医学 | 931篇 |
肿瘤学 | 18431篇 |
出版年
2023年 | 469篇 |
2022年 | 1203篇 |
2021年 | 1907篇 |
2020年 | 1103篇 |
2019年 | 1402篇 |
2018年 | 23360篇 |
2017年 | 18390篇 |
2016年 | 20608篇 |
2015年 | 2361篇 |
2014年 | 2679篇 |
2013年 | 2977篇 |
2012年 | 10241篇 |
2011年 | 24099篇 |
2010年 | 20526篇 |
2009年 | 12993篇 |
2008年 | 21711篇 |
2007年 | 23939篇 |
2006年 | 2751篇 |
2005年 | 4127篇 |
2004年 | 5108篇 |
2003年 | 5822篇 |
2002年 | 3755篇 |
2001年 | 669篇 |
2000年 | 740篇 |
1999年 | 463篇 |
1998年 | 427篇 |
1997年 | 349篇 |
1996年 | 255篇 |
1995年 | 219篇 |
1994年 | 205篇 |
1993年 | 149篇 |
1992年 | 202篇 |
1991年 | 253篇 |
1990年 | 260篇 |
1989年 | 206篇 |
1988年 | 168篇 |
1987年 | 140篇 |
1986年 | 113篇 |
1985年 | 155篇 |
1984年 | 104篇 |
1983年 | 85篇 |
1982年 | 94篇 |
1981年 | 64篇 |
1980年 | 87篇 |
1979年 | 56篇 |
1978年 | 56篇 |
1974年 | 58篇 |
1938年 | 63篇 |
1932年 | 57篇 |
1930年 | 48篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
杨娅 Thomas Bartel Loredana Latina Guido Caspari 王新房 Raimund Erbel 《华中科技大学学报(医学英德文版)》2002,22(2):158-163
Coronary flow reserve (CFR) has been used toassess coronary microcirculation and epicardial coro-nary stenoses[1— 3 ] . CFR is defined as the ratio ofcoronary flow under maximal coronary vasodilatationto coronary flow under resting conditions[4 ] .Whenthe cross- sectional area of epicardial coronary arteriesis constant,coronary flow velocity (CFV) ratios areequal to volume flow ratios.The most common method used clinically formeasuring CFVR is intracoronary Doppler flow(ICD) analysis re… 相似文献
62.
63.
64.
T. M. Skerry M.D. M.R.C.V.S. R. Suswillo A. J. El Haj N. N. Ali R. A. Dodds L. E. Lanyon 《Calcified tissue international》1990,46(5):318-326
Summary Previous studies of Alcian blue-induced birefringence in adult avian cortical bone showed that a short period of intermittent
loading rapidly produces an increased level of orientation of proteoglycans within the bone tissue. In the absence of further
loading, this persists for over 24 hours. We have proposed that this phenomenon could provide a means for “capturing” the
effects of transient strains, and so provide a persistent, constantly updated strain-related influence on osteocyte populations
related to the bones' averaged recent strain history, in effect, a “strain memory” in bone tissue. In our present study, we
use the Alcian blue-induced birefringence technique to demonstrate that proteoglycan orientation also occurs after intermittent
loading of both cortical and cancellous mammalian bonein vivo andin vitro. We also show that the change in birefringence is proportional to the magnitude of the applied strain, and that the reorientation
occurs rapidly, reaching a maximal value after only 50 loading cycles. Examination of electron micrographs of bone tissue
after staining with cupromeronic blue allows direct visualization and quantification of the change in proteoglycan orientation
produced by loading. This shows that intermittent loading is associated with a realignment of the proteoglycan protein cores,
bringing them some 5 degrees closer to the direction of collagen fibrils in the bone matrix. 相似文献
65.
Irwin L. Flink 《Brain structure & function》2002,205(3):235-244
66.
In acute experiments on anesthetized cats with total ischemia of the brain (15-minute arrest of blood autoperfusion of the cerebral vessels by a stable blood volume) it was shown that euphylline and no-shpa administered before ischemia or in the early period after ischemia inhibit or prevent the development of the postischemic phenomenon of non-recovery of the cerebral blood flow. The two drugs contributed to survival of albino rats following the brain ischemia produced by ligation of both carotid arteries. 相似文献
67.
Loss of basal forebrain P75(NTR) immunoreactivity in subjects with mild cognitive impairment and Alzheimer's disease. 总被引:13,自引:0,他引:13
Elliott J Mufson Shuang Y Ma John Dills Elizabeth J Cochran Sue Leurgans Joanne Wuu David A Bennett Syed Jaffar Michelle L Gilmor Alan I Levey Jeffrey H Kordower 《The Journal of comparative neurology》2002,443(2):136-153
The long-held belief that degeneration of the cholinergic basal forebrain was central to Alzheimer's disease (AD) pathogenesis and occurred early in the disease process has been questioned recently. In this regard, changes in some cholinergic basal forebrain (CBF) markers (e.g. the high affinity trkA receptor) but not others (e.g., cortical choline acetyltransferase [ChAT] activity, the number of ChAT and vesicular acetylcholine transporter-immunoreactive neurons) suggest specific phenotypic changes, but not frank neuronal degeneration, early in the disease process. The present study examined the expression of the low affinity p75 neurotrophin receptor (p75(NTR)), an excellent marker of CBF neurons, in postmortem tissue derived from clinically well-characterized individuals who have been classified as having no cognitive impairment (NCI), mild cognitive impairment (MCI), and mild AD. Relative to NCI individuals, a significant and similar reduction in the number of nucleus basalis p75(NTR)-immunoreactive neurons was seen in individuals with MCI (38%) and mild AD (43%). The number of p75(NTR)-immunoreactive nucleus basalis neurons was significantly correlated with performance on the Mini-Mental State Exam, a Global Cognitive Test score, as well as some individual tests of working memory and attention. These data, together with previous reports, support the concept that phenotypic changes, but not frank neuronal degeneration, occur early in cognitive decline. Although there was no difference in p75(NTR) CBF cell reduction between MCI and AD, it remains to be determined whether these findings lend support to the hypothesis that MCI is a prodromal stage of AD. 相似文献
68.
69.
70.
The concentration of microsomal cytochromes P-450, and of protein in the homogenate, cytosol and microsomes were measured in the liver, kidney and duodenal mucosa of healthy well-fed male and female camels, sheep and goats. For comparison, data from the liver of male and female rats were also obtained. The protein concentrations in the tissues of adult animals were broadly similar in the four species. The concentration of cytochromes P-450 was highest in the liver, followed by the kidney, then the duodenal mucosa in all the species. No cytochromes P-450 were detected in the tissues of immature (less than 1 mo) male goats, whereas the female goat had the highest concentrations of these enzymes in the liver and kidney when compared with the respective tissues in the other species studied. Males had higher activity of cytochromes P-450 than females in the three tissues, except in the duodenal mucosa of sheep, where males had lower activity than females. In camel liver and sheep kidney, the amount of cytochromes P-450 were similar in the two sexes. The present results suggest that the mature female goat is the species best equipped to handle xenobiotics which are detoxified by the cytochromes P-450 and other drug metabolizing enzymes in diseased or malnourished animals is suggested as these two conditions are known to modify drug metabolizing enzymes. 相似文献