全文获取类型
收费全文 | 3428581篇 |
免费 | 256000篇 |
国内免费 | 9202篇 |
专业分类
耳鼻咽喉 | 46452篇 |
儿科学 | 113216篇 |
妇产科学 | 95768篇 |
基础医学 | 481978篇 |
口腔科学 | 94790篇 |
临床医学 | 314847篇 |
内科学 | 673941篇 |
皮肤病学 | 81403篇 |
神经病学 | 282550篇 |
特种医学 | 130839篇 |
外国民族医学 | 1111篇 |
外科学 | 512575篇 |
综合类 | 74100篇 |
现状与发展 | 7篇 |
一般理论 | 1346篇 |
预防医学 | 267723篇 |
眼科学 | 77742篇 |
药学 | 248460篇 |
8篇 | |
中国医学 | 7250篇 |
肿瘤学 | 187677篇 |
出版年
2019年 | 27451篇 |
2018年 | 38514篇 |
2017年 | 29569篇 |
2016年 | 33977篇 |
2015年 | 38264篇 |
2014年 | 53324篇 |
2013年 | 80034篇 |
2012年 | 106795篇 |
2011年 | 113286篇 |
2010年 | 67872篇 |
2009年 | 64784篇 |
2008年 | 105306篇 |
2007年 | 111729篇 |
2006年 | 113568篇 |
2005年 | 109284篇 |
2004年 | 104818篇 |
2003年 | 101066篇 |
2002年 | 97636篇 |
2001年 | 165442篇 |
2000年 | 169484篇 |
1999年 | 142527篇 |
1998年 | 41227篇 |
1997年 | 36711篇 |
1996年 | 36735篇 |
1995年 | 35528篇 |
1994年 | 32430篇 |
1993年 | 30346篇 |
1992年 | 110055篇 |
1991年 | 105625篇 |
1990年 | 102360篇 |
1989年 | 98612篇 |
1988年 | 90461篇 |
1987年 | 88613篇 |
1986年 | 82990篇 |
1985年 | 79433篇 |
1984年 | 59570篇 |
1983年 | 50492篇 |
1982年 | 30189篇 |
1981年 | 26934篇 |
1979年 | 52665篇 |
1978年 | 37282篇 |
1977年 | 31409篇 |
1976年 | 29259篇 |
1975年 | 30841篇 |
1974年 | 36737篇 |
1973年 | 35108篇 |
1972年 | 32998篇 |
1971年 | 30510篇 |
1970年 | 28356篇 |
1969年 | 27002篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
991.
Abstract – The type of liquid medium used to store avulsed teeth prior to replantation has been shown to affect the long‐term prognosis. One possibility is that some storage media contain hydrogen peroxide (H2O2) that may be toxic to periodontal ligament cells. Therefore, the aim of this study was to determine if the addition of catalase to storage media improved the prognosis of replanted dog teeth. Forty‐eight mongrel premolar roots were endodontically treated, extracted, randomly divided and placed into one of four storage media: Hank's balanced salt solution (HBSS), containing no antioxidant); Viaspan, containing the antioxidant, glutathione, or the same two media supplemented with catalase(100 U ml?1) for 1, 5, or 26 h prior to replantation. After 2 months, the dogs were euthanized and the roots histologically examined to evaluate the attachment tissues. Regardless of the storage medium used, overall healing was excellent and only 4% of the roots displayed inflammatory or replacement resorption. When roots from the different storage media were compared, those stored in HBSS were found to display the highest incidence of surface resorption (55.7%). Supplementation of HBSS with catalase resulted in a lower level of surface resorption (48.6%) that was statistically significant (P < 0.05). Roots stored in Viaspan – or + catalase displayed even lower levels of surface resorption (41.3 and 38.2%, respectively). The improvement observed with catalase‐supplemented HBSS was confined to the 45‐min incubation period; only Viaspan – or + catalase reduced surface resorption at the 5‐ and 26‐h incubations. Collectively, these data demonstrate that roots stored in media containing antioxidant activity undergo less surface resorption. These results suggest that low levels of H2O2 in storage media for avulsed teeth may adversely affect periodontal ligament cells. 相似文献
992.
993.
T. Svara M. Gombac M. Vrecl P. Juntes R. Kostanjsek A. Pogacnik M. Pogacnik 《Transboundary and Emerging Diseases》2006,53(1):26-29
Clinicopathological and electron microscopical findings of eight cases of enzootic nasal adenocarcinoma of sheep, diagnosed solely in one big flock in Slovenia between years 2001 and 2003 are described. All affected sheep were female, their mean age was 4.5 ± 1.5 years and they either belonged to the Istrian pramenka breed (five sheep) or were crossbreeds (three sheep). Tumours that arose from the ethmoid area of the nasal cavity were unilateral in six cases (75%) and bilateral in two cases (25%). All tumours were classified as adenocarcinomas by histopathological examination and they displayed either a combination of tubular and papillary growth or less often solely tubular proliferation. No metastases were detected in regional lymph nodes, brain or other organs. Electron microscopical studies performed on the reprocessed paraffin‐embedded tissues revealed the presence of the virus‐like particles with an average diameter between 70 and 90 nm. 相似文献
994.
995.
996.
997.
998.
C Rubino V Coscia A M Cavazzuti V Canu 《Journal of plastic, reconstructive & aesthetic surgery》2006,59(6):636-643
Perforator flaps are perfused through a long vessel whose calibre decreases from its origin to the skin, because all branches have been sealed, resulting in a conduit with resistances in series, rather than a tree with resistances in parallel, as in the normal systemic circulation. This study was planned to assess whether the differences between perforator flap and normal systemic vasculature have an impact on haemodynamic parameters in perforator flaps and on their clinical significance. The study was performed on 10 patients. Echo-colour-Doppler measurement of diameters, velocity of flow and calculations of flow rate were made at the level of flap pedicle artery and skin perforator artery, pre- and post-operatively in each patient. Statistical analysis used the Wilcoxon matched pairs signed sum rank test. Our data show that in the donor area pre-operatively, blood velocity in skin artery perforator is lower that in the corresponding pedicle artery, whereas post-operatively, in perforator flaps, blood velocity in the perforator is higher than in the pedicle. The difference was statistically significant (P<0.01). There is an inversion of the gradient of blood velocity between pedicle artery and perforator artery compared to normal circulation. Furthermore, in normal circulation flow through the perforator was found smaller than that at the pedicle, whereas in perforator flaps, flow through the perforator is smaller but is a greater proportion of the flow through the pedicle and the difference is statistically significant (P<0.01). Therefore, the velocity of blood and the rate of flow reaching the skin are higher in perforator flaps than in normal circulation. 相似文献
999.
Abstract Chorea is a rare complication of polycythaemia vera. Polycythaemic chorea occurs predominantly in females and usually in generalised
form. We present a 66-year-old woman with acute onset hemichorea-ballism with no vascular pathology in the basal ganglia region.
A clear relationship was observed between the onset of chorea and worsening of haematological parameters in the patient. After
repeated phlebotomies the patient's clinical status was improved. Polycythaemic chorea must be considered, especially in the
elderly, as early diagnosis leads to effective treatment and prevention of complications. 相似文献
1000.
A new semi-empirical formula for the evaluation of (n,(3)He) reaction cross-sections at the energy of 14.6 and 20 MeV is presented. Formula was derived using the analytical expression for the evaluation of the (3)He spectrum within the frame of pre-equilibrium exciton model. The systematics obtained is compared with the empirical formula for the (n,(3)He) reaction cross-section. 相似文献