全文获取类型
收费全文 | 1867篇 |
免费 | 142篇 |
国内免费 | 23篇 |
专业分类
耳鼻咽喉 | 4篇 |
儿科学 | 52篇 |
妇产科学 | 20篇 |
基础医学 | 203篇 |
口腔科学 | 100篇 |
临床医学 | 252篇 |
内科学 | 354篇 |
皮肤病学 | 9篇 |
神经病学 | 121篇 |
特种医学 | 205篇 |
外科学 | 170篇 |
综合类 | 77篇 |
预防医学 | 233篇 |
眼科学 | 15篇 |
药学 | 155篇 |
中国医学 | 2篇 |
肿瘤学 | 60篇 |
出版年
2022年 | 10篇 |
2021年 | 24篇 |
2020年 | 15篇 |
2019年 | 25篇 |
2018年 | 41篇 |
2017年 | 17篇 |
2016年 | 23篇 |
2015年 | 29篇 |
2014年 | 39篇 |
2013年 | 90篇 |
2012年 | 92篇 |
2011年 | 73篇 |
2010年 | 66篇 |
2009年 | 54篇 |
2008年 | 76篇 |
2007年 | 98篇 |
2006年 | 71篇 |
2005年 | 69篇 |
2004年 | 67篇 |
2003年 | 50篇 |
2002年 | 53篇 |
2001年 | 50篇 |
2000年 | 45篇 |
1999年 | 52篇 |
1998年 | 41篇 |
1997年 | 35篇 |
1996年 | 51篇 |
1995年 | 28篇 |
1994年 | 38篇 |
1993年 | 36篇 |
1992年 | 46篇 |
1991年 | 31篇 |
1990年 | 43篇 |
1989年 | 45篇 |
1988年 | 39篇 |
1987年 | 49篇 |
1986年 | 28篇 |
1985年 | 37篇 |
1984年 | 20篇 |
1983年 | 19篇 |
1982年 | 32篇 |
1981年 | 19篇 |
1980年 | 13篇 |
1979年 | 11篇 |
1977年 | 15篇 |
1976年 | 26篇 |
1975年 | 10篇 |
1974年 | 14篇 |
1969年 | 9篇 |
1968年 | 9篇 |
排序方式: 共有2032条查询结果,搜索用时 15 毫秒
21.
Devlin CM Chawl S Skepper JN Huan CL 《Journal of muscle research and cell motility》2001,22(5):459-466
The transverse (T-)tubules primarily function in conducting the action potentials that initiate excitation– contraction coupling
in skeletal muscle but may additionally subserve longer-term roles in volume regulation, membrane fusion and other trafficking
processes. Osmotic shock thus both electrically detaches the T-tubules from surface membrane (‘detubulation’) and produces
tubular vacuolation. The present experiments separated these effects. An established, reference osmotic shock protocol that
exposed muscles to Ca2+/Mg2+-Ringer and gradual cooling to 10°C after 18 min in glycerol–Ringer accomplished significant detubulation (77.5 ± 13.15%,
mean ± SEM; n = 4). In contrast, a test protocol conducted entirely at room temperature using Mg2+-rather than Ca2+/Mg2+-Ringer yielded reduced (P < 0.05, post hoc Duncan's multiple range test) detubulation indices (1.67 ± 1.67%, n = 6) statistically indistinguishable from findings in fibres spared osmotic shock. Yet both osmotic shocks caused a formation
of closed vacuoles, demonstrated by Sulphorhodamine B trapping, that occupied statistically similar fractions of total fibre
volume (reference procedure: 14.38 ± 2.7%, n = 6; test procedure: 13.36 ± 2.00%, n = 22) in turn higher than determinations in control fibres (P < 0.05). The findings reconcile reports associating detubulation with vacuolation in osmotically shocked muscle [S. Nik-Zainal
et al. (1999) J Muscle Res Cell Motil
20: 45–53; K.N. Khan et al. (2000) J Muscle Res Cell Motil
21: 79–90] with the persistence of tubular electrical activity in extensively vacuolated amphibian fibres following fatigue [J.
Lannergren and H. Westerblad (1987) Acta Physiol Scand
129: 311–318; J. Lannergren et al. (1999) J Muscle Res Cell Motil
20: 19–32]. Furthermore test protocols produced higher densities of open vacuoles (13.38 ± 2.33%, n = 9) than did reference protocols (6.66 ± 1.63%, n = 20) contrary to their possible involvement in the electrophysiological changes. Abolition of tubular electrophysiological
activity thus either follows or is independent of tubular vacuolation whilst sharing some of its underlying osmotic mechanisms.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
22.
Breast cancer detection: one versus two views 总被引:2,自引:0,他引:2
Mammographic examinations of 169 patients with 172 biopsy-proved carcinomas, and of 194 healthy subjects, were interpreted independently and retrospectively by three experienced mammographers, initially as single-view oblique examinations and 6 months later as two-view oblique-cephalocaudal examinations. For the single-view examinations of the cancer patients, 67% of the cancers were correctly recommended for biopsy, additional views were requested for 23%, and a "negative" interpretation was made for 10%. For the single-view examinations of healthy subjects, biopsy was recommended for 7% and additional views were recommended for 32%. For the two-view examinations of women with cancer, 80% of the cancers were correctly recommended for biopsy, additional views were requested for 4%, and a "negative" interpretation was made for 16%. For two-view examinations of healthy subjects, biopsy was recommended for 7% and additional views were requested for only 5%. The authors conclude that single-view screening should not be performed, because it would lead to an excessive number of "call-back" examinations of healthy patients, producing additional cost and anxiety that would outweigh any theoretical benefit. 相似文献
23.
Striated intramural gallbladder lucencies on US studies: predictors of acute cholecystitis 总被引:1,自引:0,他引:1
Ultrasound scans of 51 consecutive patients with gallbladder wall thickening were reviewed, and specific sonographic features were correlated with surgical and clinical follow-up. Two patterns of thickening were identified as specific indicators of the presence or absence of acute cholecystitis. "Striated" wall thickening, consisting of several alternating, irregular, discontinuous, lucent and echogenic bands, was seen in eight of 13 patients (62%) with acute cholecystitis. This pattern was not encountered in any of the patients who did not have acute cholecystitis. Conversely, "three-layer" thickening, consisting of a single circumferential lucent zone between two relatively uniform echogenic layers, was seen in only one of 13 patients (8%) with acute cholecystitis but in 11 of 38 patients (29%) with other diagnoses. Other abnormalities, including the presence of intramural echogenic foci and wall irregularities, were more frequently seen in patients with acute cholecystitis but were not as helpful. Use of these features may suggest or help exclude a diagnosis of acute cholecystitis in those patients in whom the cause of gallbladder wall thickening is otherwise not apparent. 相似文献
24.
25.
26.
27.
Jowitt N MacFarlane T Devlin H Klemetti E Horner K 《Dento maxillo facial radiology》1999,28(3):141-144
OBJECTIVES: To assess the reproducibility and diagnostic validity of Mandibular Cortical Index (MCI) when used by minimally trained observers. METHODS: Four 'experts' and 45 final-year dental students classified the appearance of the lower border of the mandibular cortex in 30 panoramic radiographs using the MCI. Experts viewed the original radiographs. The students received instruction in the MCI and viewed slides of the radiographs in a lecture theatre. RESULTS: For intra-observer agreement, the experts had significantly higher overall values of weighted kappa, indicating substantial agreement in MCI assessment, whereas the students showed moderate agreement. For inter-observer agreement, there was fair agreement between the experts and poor agreement between the students. Using the experts' MCI assessment as the 'gold standard', the mean sensitivity of the students in diagnosis of C3 was 0.71 (maximum 0.95, minimum 0.25) and mean specificity was 0.56 (maximum 0.9, minimum 0.20). CONCLUSIONS: The MCI has important limitations in terms of intra- and inter-observer agreement. Minimal training in its use, such as might be given in a lecture format to dentists, was ineffective and associated with poor inter-observer agreement and limited diagnostic validity in identifying signs of osteoporosis. More lengthy training and experience in using the MCI would be needed for it to be effective as a diagnostic tool in general dental practice. 相似文献
28.
29.
30.