全文获取类型
收费全文 | 1785篇 |
免费 | 123篇 |
国内免费 | 5篇 |
专业分类
耳鼻咽喉 | 15篇 |
儿科学 | 47篇 |
妇产科学 | 55篇 |
基础医学 | 171篇 |
口腔科学 | 38篇 |
临床医学 | 143篇 |
内科学 | 301篇 |
皮肤病学 | 6篇 |
神经病学 | 179篇 |
特种医学 | 276篇 |
外科学 | 204篇 |
综合类 | 13篇 |
预防医学 | 101篇 |
眼科学 | 172篇 |
药学 | 51篇 |
中国医学 | 4篇 |
肿瘤学 | 137篇 |
出版年
2022年 | 15篇 |
2021年 | 18篇 |
2020年 | 28篇 |
2019年 | 46篇 |
2018年 | 37篇 |
2017年 | 38篇 |
2016年 | 36篇 |
2015年 | 59篇 |
2014年 | 48篇 |
2013年 | 105篇 |
2012年 | 113篇 |
2011年 | 110篇 |
2010年 | 64篇 |
2009年 | 67篇 |
2008年 | 117篇 |
2007年 | 112篇 |
2006年 | 95篇 |
2005年 | 89篇 |
2004年 | 67篇 |
2003年 | 52篇 |
2002年 | 50篇 |
2001年 | 26篇 |
2000年 | 16篇 |
1999年 | 20篇 |
1998年 | 14篇 |
1997年 | 15篇 |
1996年 | 14篇 |
1994年 | 10篇 |
1992年 | 12篇 |
1991年 | 14篇 |
1990年 | 26篇 |
1989年 | 12篇 |
1988年 | 9篇 |
1987年 | 17篇 |
1986年 | 15篇 |
1985年 | 10篇 |
1983年 | 14篇 |
1982年 | 14篇 |
1981年 | 12篇 |
1974年 | 9篇 |
1973年 | 7篇 |
1943年 | 10篇 |
1942年 | 8篇 |
1941年 | 20篇 |
1940年 | 16篇 |
1939年 | 31篇 |
1938年 | 23篇 |
1937年 | 7篇 |
1935年 | 23篇 |
1933年 | 13篇 |
排序方式: 共有1913条查询结果,搜索用时 15 毫秒
1.
Reporting of the clinical relevant dose to organs at risk (OR) and other normal tissues is crucial in trials and protocols where the aim is to assess late complications and to increase the therapeutic ratio for external beam radiotherapy. The dose distribution in normal tissues and ORs are, however, most often heterogeneous, at least when more than two opposing beams are applied. To decide the most clinical relevant dose with respect to late occurring complications is therefore not a straight forward problem. In this work we discuss what parameters characterise the dose-volume-histogram (DVH) best by calculating normal tissue complication probabilities (NTCPs) by using the Lyman model and various sets of statistical parameters drawn out from the DVHs. These NTCPs are compared to NTCPs calculated from the full DVHs, when the sets of parameters are evaluated. Our calculations indicate that the NTCP based on the Lyman model is best correlated to the Dmax value, for serially organised tissues such as the spinal cord. For organs, described largely as tissues organised in parallel, the Dmedian or Dmean of the DVH may be applied. Our calculations reveal that Dmean is the parameter of choice when Dmeclian is quite small, but when the two parameters approach each other, Dmediarl will be a better choice, using a unity volume fraction. For ORs characterised by a mixed serial and parallel functional structure, as the heart, neither Dmax, Dmedian, nor Dmi,an may predict the actual NTCP. 相似文献
2.
Cyclodextrin formulation of dorzolamide and its distribution in the eye after topical administration. 总被引:2,自引:0,他引:2
Hakon H Sigurdsson Einar Stefánsson Elínborg Gudmundsdóttir Thór Eysteinsson Margrét Thorsteinsdóttir Thorsteinn Loftsson 《Journal of controlled release》2005,102(1):255-262
Due to limited aqueous solubility of dorzolamide at physiologic pH, the pH of Trusopt eye drops (cont. 2% dorzolamide) has to be kept at about 5.65, and to increase the topical bioavailability of the drug from Trusopt the contact time of the drug with the eye surface is increased by increasing the viscosity of the eye drops to 100 cps. This low pH and high viscosity can lead to local irritation. In this study, dorzolamide hydrochloride was formulated as 2% and 4% low viscosity solutions (viscosity 3 to 5 cps) containing randomly methylated beta-cyclodextrin at pH 7.45. These formulations were evaluated in rabbits. The animals were sacrificed at various time points after topical administration of the drug and the dorzolamide concentration determined in the different parts of the eye. Trusopt was used as a reference standard. The topical availability of dorzolamide from the cyclodextrin-containing eye drops appeared to be comparable to that from Trusopt and the drug reached retina and optic nerve to give measurable concentrations for at least 8 h after administration of the eye drops. 相似文献
3.
Kinzl Geelen F. Ferrio Langsteiner Dubitscher Pfister H. Donalies Kranz G. A. Adam Koller v. Baeyer Zillig G. Rost Sjvall Einar Hahn Rubner Max H. Hofmann Bresowsky Mller H. Liguori-Hohenauer Geller Braun F. Leibbrand Tbben H. 《International journal of legal medicine》1940,33(4):353-364
International Journal of Legal Medicine - 相似文献
4.
5.
Between 1944 and 1947 the mortality statistics for the Danish population show an epidemic increase of liver diseases: subacute necrosis and cirrhosis. The epidemic only affected female mortality rates. Mortality due to cirrhosis remained at a higher rate for women than men until 1970 as a result of an excess mortality in the cohort of women who in 1945 were over the age of 45. Up to 1981 this group showed an excess of 4,000 fatalities. A reevaluation of medico-statistical data shows that the disease cannot be explained by the epidemic hepatitis occurring in 1942-1944 or by increased consumption of alcohol. Possible causes could be pharmaceutical products or additives, perhaps hormone preparations. 相似文献
6.
Leif Ivar Havelin Nils Roar Gjerdet Ole Dankert Lunde Milan Rait Einar Sudmann 《Acta orthopaedica》1986,57(5):419-422
The wear was examined in 39 Christiansen total hip prostheses, which were removed because of mechanical loosening after being used 5 (3-11) years. In the polyacetal acetabular cups, the head had made an eccentric defect, the mean volume of which was 680 (180-3310) mm3. The mean penetration of the head into the wall of the cup was 0.8 (0.1-3.2) mm. In two additional cups the head had penetrated right through the wall of the cup. In three prostheses the polyacetal sleeve of the trunnion was so worn that the head bore directly on the stem. There was a positive correlation between wear and the time the prostheses had been used before symptoms of loosening presented. 相似文献
7.
Divers' lung function: small airways disease? 总被引:3,自引:0,他引:3
E Thorsen K Segadal B Kambestad A Gulsvik 《British journal of industrial medicine》1990,47(8):519-523
Pulmonary function was measured in 152 professional saturation divers and in a matched control group of 106 subjects. Static lung volumes, dynamic lung volumes and flows, transfer factor for carbon monoxide (T1CO), transfer volume per unit alveolar volume (KCO), delta-N2, and closing volume (CV) were measured and compared with reference values from recent Scandinavian studies, British submariners, and the European Community for Coal and Steel (ECCS) recommended reference values. Diving exposure was assessed as years of diving experience, total number of days in saturation and depth, and as the product of days in saturation and mean depth. Divers had significantly lower values for forced expired volume in one second (FEV1), FEV1/forced vital capacity (FVC) ratio, FEF25-75%, FEF75-85%, FEF50%, FEF75%, T1CO, and KCO compared with the controls and a significantly higher CV. There was a positive correlation between diving exposure and CV, whereas the other variables had negative correlations with diving exposure. Values for the control group were not different from the predictive values of Scandinavian reference studies or British submariners, although the ECCS standard predicted significantly lower values for the lung function variables both in divers and the control group. The pattern of the differences in lung function variables between the divers and controls is consistent with small airways dysfunction and with the transient changes in lung function found immediately after a single saturation dive. The association between reduced pulmonary function and previous diving exposure further indicates the presence of cumulative long term effects of diving on pulmonary function. 相似文献
8.
Ivar Rønnestad Einar Thorsen Kåre Segadal Arvid Hope 《European journal of applied physiology》1994,69(1):32-35
In diving, pulmonary mechanical function is limited by the increased density of the gas breathed. Breathing cold and dry gas may cause an additional increase in airways resistance. We have measured forced vital capacity, forced expired volume in 1 s (FEV1) and forced midexpiratory flow rate (FEF25%–75%) before and after breathing dry or humid gas at 29–32°C during a standardized exercise intensity on a cycle ergometer at an ambient pressure of 3.7 MPa. The atmosphere was a helium and oxygen mixture with a density of 6.8 kg · m–3. Six professional saturation divers aged 26–37 years participated in the study. There were no significant differences in convective respiratory heat loss between the exposures. The mean evaporative heat loss was 67 W (range 59–89) breathing dry gas and 37 W (range 32–43) breathing humid gas, corresponding to water losses of 1.7 g · min–1 (range 1.5–2.2) and 0.9 g · min–1 (range 0.8–1.1), respectively. There was a significant reduction in FEV1 of 4.6 (SD 3.6)% (P<0.05), and in FEF25%–75% of 5.8 (SD 4.7)% (P<0.05) after breathing dry gas. There were no changes after breathing humid gas. By warming and humidifying the gas breathed in deep saturation diving bronchoconstriction may be prevented. 相似文献
9.
10.