全文获取类型
收费全文 | 1417篇 |
免费 | 99篇 |
国内免费 | 1篇 |
专业分类
耳鼻咽喉 | 15篇 |
儿科学 | 125篇 |
妇产科学 | 36篇 |
基础医学 | 116篇 |
口腔科学 | 15篇 |
临床医学 | 101篇 |
内科学 | 273篇 |
皮肤病学 | 41篇 |
神经病学 | 107篇 |
特种医学 | 33篇 |
外科学 | 307篇 |
综合类 | 19篇 |
预防医学 | 59篇 |
眼科学 | 55篇 |
药学 | 126篇 |
中国医学 | 2篇 |
肿瘤学 | 87篇 |
出版年
2023年 | 12篇 |
2022年 | 30篇 |
2021年 | 62篇 |
2020年 | 37篇 |
2019年 | 51篇 |
2018年 | 67篇 |
2017年 | 42篇 |
2016年 | 40篇 |
2015年 | 42篇 |
2014年 | 70篇 |
2013年 | 87篇 |
2012年 | 126篇 |
2011年 | 121篇 |
2010年 | 64篇 |
2009年 | 58篇 |
2008年 | 85篇 |
2007年 | 80篇 |
2006年 | 64篇 |
2005年 | 62篇 |
2004年 | 40篇 |
2003年 | 30篇 |
2002年 | 29篇 |
2001年 | 22篇 |
2000年 | 37篇 |
1999年 | 14篇 |
1998年 | 6篇 |
1997年 | 7篇 |
1996年 | 2篇 |
1995年 | 4篇 |
1994年 | 6篇 |
1993年 | 4篇 |
1992年 | 16篇 |
1991年 | 10篇 |
1990年 | 7篇 |
1989年 | 10篇 |
1988年 | 7篇 |
1987年 | 8篇 |
1986年 | 5篇 |
1985年 | 6篇 |
1984年 | 6篇 |
1983年 | 6篇 |
1982年 | 4篇 |
1976年 | 2篇 |
1975年 | 2篇 |
1974年 | 2篇 |
1973年 | 2篇 |
1971年 | 2篇 |
1968年 | 2篇 |
1967年 | 3篇 |
1924年 | 2篇 |
排序方式: 共有1517条查询结果,搜索用时 15 毫秒
1.
Toscana virus was maintained in a laboratory colony of Phlebotomus perniciosus by vertical (transovarial) transmission for 13 consecutive generations over a 23-month period. No significant biological changes were noted in the virus after prolonged vertical passage in the sand flies, and transovarially infected females were able to transmit the agent by bite to susceptible animals. Chronic infection of Ph. perniciosus with Toscana virus had no apparent effect on the insects' rate of eclosion. In the absence of selection and with random matings, the virus infection rates in each subsequent generation of the colony decreased, suggesting that Toscana virus cannot be maintained in Ph. perniciosus by transovarial transmission alone. Alternative mechanisms for virus maintenance are discussed. 相似文献
2.
Unsteady Fluid Dynamics of Several Mechanical Prosthetic Heart Valves Using a Two Component Laser Doppler Anemometer System 总被引:5,自引:0,他引:5
Abstract: Five typical mechanical heart valves (Starr-Edwards, Björk-Shiley convexo-concave (c-c), Björk-Shiley monostrut, Bicer-Val, and St. Jude Medical) were tested in the mitral position under the pulsatile flow condition. The test program included measurements of velocity and turbulent stresses at 5 downstream locations. The study was carried out using a sophisticated cardiac simulator in conjunction with a highly sensitive 2 component laser Doppler anemometer (LDA) system. The continuous monitoring of parametric time histories revealed useful details about the complex flow and helped to establish the locations and times of the peak parameter values. Based upon the nondimensional presentation of data, the following general conclusions can be made. First, all the 5 valve designs created elevated turbulent stresses during the accelerating and peak flow phases, presenting the possibility of thromboembolism and perhaps hemolysis. Second, the difference in valve configuration seemed to affect the flow characteristics; third, the bileaflet design of the St. Jude valve appeared to create a lower turbulence stress level. 相似文献
3.
To ascertain the potential role of reactive oxygen metabolites in the pathophysiology of obstructive uropathy, we examined the effect of probucol, an antioxidant agent, on renal function in normal rats and rats with unilateral release of bilateral ureteral obstruction (BUO) of 24 hours duration. Rats were fed either a standard diet or a standard diet containing one percent probucol for two weeks prior to study. Probucol lowered serum cholesterol in both normal and BUO rats. Probucol did not significantly affect renal function in normal rats. BUO rats given probucol had greater inulin and PAH clearances at three to five hours and three days following release of BUO than rats with BUO not given probucol. Kidneys from obstructed rats had higher levels of malondialdehyde, an index of lipid peroxidation, a greater number of leukocytes in the cortex, decreased levels of reduced glutathione and increased levels of oxidized glutathione. Renal cortex from obstructed rats treated with probucol had significantly higher levels of reduced glutathione than kidneys of obstructed rats not given probucol. A decrease in cholesterol, using another lipid-lowering agent, lovastatin, did not modify renal function in rats with BUO. The data can be interpreted to indicate a role for reactive oxygen species in the pathophysiology of obstructive nephropathy. The improved renal function seen in probucol-treated rats with BUO may be due to an effect of this agent in affecting accumulation of reactive oxygen metabolites and/or decreasing the number of leukocytes infiltrating the renal cortex. 相似文献
4.
5.
J C Ruckdeschel S P Modi W el-Hamouly E Portuese S Archer 《Journal of medicinal chemistry》1992,35(26):4854-4857
A series of analogues of the antitumor alkaloids ellipticine and olivacine were tested for cytotoxicity against four human lung cancer cell lines: H69, N417, H460, and H358. Adriamycin (doxorubicin), ellipticine, olivacine, and celiptinium were used as standards. Adriamycin was cytotoxic at 2 microM and celiptinium was inactive at the highest concentrations tested (IC50 > 48 microM). N-methylcarbamates of 9-methoxy-6H-pyrido[4,3-b]carbazole 1-,5-, and 11-methanols gave IC50 values ranging from 0.02 to 0.11 microM against N417, H460, and H358 and were only slightly less effective against H69. 相似文献
6.
7.
8.
9.
Fellous JM Houweling AR Modi RH Rao RP Tiesinga PH Sejnowski TJ 《Journal of neurophysiology》2001,85(4):1782-1787
Pyramidal cells and interneurons in rat prefrontal cortical slices exhibit subthreshold oscillations when depolarized by constant current injection. For both types of neurons, the frequencies of these oscillations for current injection just below spike threshold were 2--10 Hz. Above spike threshold, however, the subthreshold oscillations in pyramidal cells remained low, but the frequency of oscillations in interneurons increased up to 50 Hz. To explore the interaction between these intrinsic oscillations and external inputs, the reliability of spiking in these cortical neurons was studied with sinusoidal current injection over a range of frequencies above and below the intrinsic frequency. Cortical neurons produced 1:1 phase locking for a limited range of driving frequencies for fixed amplitude. For low-input amplitude, 1:1 phase locking was obtained in the 5- to 10-Hz range. For higher-input amplitudes, pyramidal cells phase-locked in the 5- to 20-Hz range, whereas interneurons phase-locked in the 5- to 50-Hz range. For the amplitudes studied here, spike time reliability was always highest during 1:1 phase-locking, between 5 and 20 Hz for pyramidal cells and between 5 and 50 Hz for interneurons. The observed differences in the intrinsic frequency preference between pyramidal cells and interneurons have implications for rhythmogenesis and information transmission between populations of cortical neurons. 相似文献
10.
Kondo H Tatsumi N Sakamoto H Fernandes B Modi G Raby A 《Rinsho byori. The Japanese journal of clinical pathology》2003,51(5):480-484
The increasing complexity of diseases and advancing medical technologies have recently raised the number of test items and their use. This has caused each department to ask for clinical support by medical technologists, including consultation services on clinical laboratory tests in Japan. Under these circumstances, we think it is necessary to consider a Japanese education system for medical technologists to foster people with advanced ability capable in providing adequate clinical support. It is important that we study medical technologist systems and education systems superior to than ours. Therefore, to investigate the state of the Japanese education system for medical technologists, we conducted a comparison between the medical technologist systems and education systems in foreign countries and those of Japan. The social background in which medical technologists are positioned, their scope of work, and the education systems overseas are different from Japan on many points and we were given many suggestions for what a system in Japan should be like. 相似文献