全文获取类型
收费全文 | 1063篇 |
免费 | 121篇 |
国内免费 | 26篇 |
专业分类
耳鼻咽喉 | 9篇 |
儿科学 | 22篇 |
妇产科学 | 22篇 |
基础医学 | 78篇 |
口腔科学 | 24篇 |
临床医学 | 142篇 |
内科学 | 234篇 |
皮肤病学 | 10篇 |
神经病学 | 63篇 |
特种医学 | 129篇 |
外科学 | 209篇 |
综合类 | 62篇 |
一般理论 | 1篇 |
预防医学 | 68篇 |
眼科学 | 59篇 |
药学 | 49篇 |
肿瘤学 | 29篇 |
出版年
2022年 | 10篇 |
2021年 | 11篇 |
2019年 | 8篇 |
2018年 | 12篇 |
2016年 | 11篇 |
2015年 | 20篇 |
2014年 | 13篇 |
2013年 | 19篇 |
2012年 | 31篇 |
2011年 | 35篇 |
2010年 | 25篇 |
2009年 | 23篇 |
2008年 | 26篇 |
2007年 | 37篇 |
2006年 | 57篇 |
2005年 | 35篇 |
2004年 | 23篇 |
2003年 | 33篇 |
2002年 | 22篇 |
2001年 | 20篇 |
2000年 | 28篇 |
1999年 | 21篇 |
1998年 | 22篇 |
1997年 | 13篇 |
1996年 | 32篇 |
1995年 | 20篇 |
1994年 | 22篇 |
1993年 | 12篇 |
1992年 | 34篇 |
1991年 | 21篇 |
1990年 | 17篇 |
1989年 | 35篇 |
1988年 | 47篇 |
1987年 | 38篇 |
1986年 | 45篇 |
1985年 | 30篇 |
1984年 | 23篇 |
1983年 | 26篇 |
1982年 | 11篇 |
1981年 | 15篇 |
1980年 | 14篇 |
1979年 | 20篇 |
1978年 | 20篇 |
1977年 | 12篇 |
1976年 | 17篇 |
1975年 | 13篇 |
1974年 | 14篇 |
1973年 | 10篇 |
1972年 | 14篇 |
1971年 | 19篇 |
排序方式: 共有1210条查询结果,搜索用时 0 毫秒
11.
R. Condon W. P. Colquhoun P. Knauth R. Plett B. Neidhart D. DeVol S. Eickhoff J. Rutenfranz 《International archives of occupational and environmental health》1988,61(1-2):39-49
Summary Daily diary records of sleep and activity, and 4-h measurements of body temperature, performance and subjective alertness were collected on board ship from 15 watchkeepers on the 4-on/8-off system, and from 28 dayworkers, on both westward and eastward transatlantic voyages. The data from a balanced sample of the subjects were analysed over selected 8-d periods of the voyages where four or five time zones were crossed. During these periods the average amount of daily sleep obtained by dayworkers on the eastward voyage was more than 1 h less than that on the westward voyage, and its quality was rated lower. Watchkeepers' main sleep was also shorter when travelling eastward, but this reduction was partially compensated for by a slightly longer secondary sleep. With the exception of subjective alertness on the eastward voyage, the basic phase of the circadian rhythms in the measured variables adjusted appropriately to the clock changes associated with the time zone crossings. The normal shape of the average daily curves was, however, altered differentially in the two directions of travel; as a result, morning levels of all variables were lower on the eastward voyage than on the westward, but evening levels were higher. These distortions of rhythm waveforms, which probably arose from a combination of endogenous and exogenous factors, add another dimension to the basic problem caused by the effects of circadian rhythms on operational efficiency in the shipboard situation. This problem can only be solved by the development of alternative watchkeeping systems which take full account of these rhythms.Partly supported by a grant from the West German Ministry for Technology and Research, Project Schiff der Zukunft, Part ET 83b 相似文献
12.
J. Rutenfranz R. Plett P. Knauth R. Condon D. DeVol N. Fletcher S. Eickhoff K. -H. Schmidt R. Donis W. P. Colquhoun 《International archives of occupational and environmental health》1988,60(5):331-339
Summary Sleep length and sleep quality scores were collected on board ships over periods of up to two weeks from 38 watchkeepers working a 4-on/8-off routine and 29 dayworkers. All watchkeepers exhibited fragmented sleeping patterns, which indicated a lack of adaptation of the sleep/wakefulness cycle to the hours of work. There were only slight differences in total sleep length between watchkeepers and dayworkers, however, both groups did not obtain an adequate amount of sleep. Within the watchkeeping crews the 3rd Officers had by far the shortest sleep length. Concerning sleep quality, daytime sleep was generally given the lowest ratings, whereas sleep starting before midnight was on average evaluated as the best, both by watchkeepers and dayworkers. Watchkeeping personnel do not normally have any days off during a voyage so that missed sleep might even amount to a sleep deficit. A solution for this problem could perhaps be a new, stabilized system that allows a single uninterrupted sleep, which is required for full recuperation, to be taken each day.Dedicated to Professor J. Aschoff on the occasion of his 75th birthdayPartly supported by a grant from the Ministry for Technology and Research, Federal Republic of Germany, Project Schiff der Zukunft, Part ET83b 相似文献
13.
14.
15.
16.
IL-1 and TNF independent pathways mediate ICAM-1/VCAM-1 up-regulation in ischemia reperfusion injury 总被引:16,自引:0,他引:16
Burne MJ Elghandour A Haq M Saba SR Norman J Condon T Bennett F Rabb H 《Journal of leukocyte biology》2001,70(2):192-198
In vitro studies have suggested that targeting interleukin (IL)-1 and tumor necrosis factor (TNF) can be used to regulate intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) and potentially treat kidney inflammation. We therefore evaluated ICAM-1 and VCAM-1 regulation in knockout (KO) mice deficient in both IL-1 receptor 1 (R1) and TNF-R1 during renal ischemia reperfusion injury. ICAM-1 and VCAM-1 mRNA expression was measured with specific murine probes and Northern blotting (n =4/group). Protein expression was measured using immunohistochemistry. Serum creatinine (SCr), tubular histology, and neutrophil infiltration into postischemic kidneys were also quantified. ICAM-1 and VCAM-1 mRNA expression increased in both wild-type (WT) and KO mice at 2, 6, and 24 h. Protein expression of ICAM-1 and VCAM-1 was also increased at 24 h postischemia. SCr levels and tubular necrosis scores were comparable in WT and KO mice at 24 and 48 h. Neutrophil migration in KO mice was decreased at 24 h but comparable to WT at 48 h. These data demonstrate that IL-1 and TNF are not essential for postischemic increases in ICAM-1 and VCAM-1. 相似文献
17.
18.
Mifsud NA Haddad AP Hart CF Holdsworth R Condon JA Swain M Sparrow RL 《Immunohematology / American Red Cross》1999,15(3):100-104
A chimeric individual possesses two or more genetically distinct cell populations. Although the chimerism may not be evident in all gene systems, various loci display greater numbers of alleles than genetically "normal" individuals. The proposita was referred for further laboratory investigation due to a mixed-field ABO blood group reaction following routine antenatal testing. Various molecular (HLA class II, ABO genotyping, and 10 short tandem repeat [STR] microsatellites) and serologic (HLA class I and red cell blood groups) typing techniques were employed to investigate a number of polymorphic loci located on different chromosomes. Chimerism was identified in 8 out of the 14 chromosomes tested: chromosome 1 (Duffy), 6 (HLA class I and II), 9 (ABO), 11 (HUMTH01), 12 (HUMPLA2A1), 15 (HUMFES/FPS), 18 (Kidd) and 21 (D21S11). The proposita was determined to be a probable dispermic chimera, based on the results of the serology and molecular studies. 相似文献
19.
Paramagnetic macrocyclic chelates show promise as magnetic resonance (MR) imaging contrast agents due to stability and relaxivity comparable to those of DTPA-type chelates. For the three copper and manganese macrocyclic complexes studied in aqueous solution, T1 and T2 relaxivities ranged from 0.14 to 5.88 mM-1sec-1 at 6.25 MHz. In rats, the intravenous administration of 16 mumol/kg of Mn(cyclam) caused the liver T1 relaxation rate to double at 15 minutes after injection. T1 measurements by pulsed MR imaging and manganese analyses on excised tissue showed that both relaxation rate (1/T1) and manganese content of liver and kidney increase linearly with the dosage of Mn(cyclam). The linear relationship between 1/T1 and manganese content can be considered an "in tissue" relaxivity plot for the agent. The resulting relaxivity is 54 mM-1sec-1 in liver, compared with 3.1 mM-1sec-1 in aqueous solution. Although this work is preliminary, the implication for medical MR imaging applications is that macrocyclic contrast agents can be effective at approximately one-tenth the current typical dose used for gadolinium DTPA. 相似文献
20.
Studies on blood samples from a 30-year-old woman of Korean origin, her husband and children, showed the presence of the cis-AB genotype in the mother and one child. The cis-AB red cells showed abnormal reactions with both polyclonal and monoclonal anti-B reagents and an elevated level of H antigen. The serum contained weak anti-B that reacted with normal B antigen but not with that on cis-AB cells. Normal levels of A substance but reduced levels of B and H substances were present in the saliva. Conversely, the serum showed reduced A and normal B and H blood group transferase activity. 相似文献