全文获取类型
收费全文 | 1160篇 |
免费 | 138篇 |
国内免费 | 9篇 |
专业分类
耳鼻咽喉 | 10篇 |
儿科学 | 29篇 |
妇产科学 | 4篇 |
基础医学 | 89篇 |
口腔科学 | 24篇 |
临床医学 | 132篇 |
内科学 | 121篇 |
皮肤病学 | 77篇 |
神经病学 | 57篇 |
特种医学 | 119篇 |
外科学 | 87篇 |
综合类 | 49篇 |
预防医学 | 154篇 |
眼科学 | 126篇 |
药学 | 130篇 |
中国医学 | 41篇 |
肿瘤学 | 58篇 |
出版年
2024年 | 5篇 |
2023年 | 32篇 |
2022年 | 70篇 |
2021年 | 97篇 |
2020年 | 76篇 |
2019年 | 75篇 |
2018年 | 74篇 |
2017年 | 53篇 |
2016年 | 34篇 |
2015年 | 33篇 |
2014年 | 98篇 |
2013年 | 66篇 |
2012年 | 50篇 |
2011年 | 67篇 |
2010年 | 57篇 |
2009年 | 38篇 |
2008年 | 45篇 |
2007年 | 41篇 |
2006年 | 35篇 |
2005年 | 21篇 |
2004年 | 20篇 |
2003年 | 26篇 |
2002年 | 19篇 |
2001年 | 18篇 |
2000年 | 18篇 |
1999年 | 12篇 |
1998年 | 13篇 |
1997年 | 5篇 |
1996年 | 6篇 |
1995年 | 3篇 |
1994年 | 4篇 |
1993年 | 5篇 |
1992年 | 9篇 |
1991年 | 14篇 |
1990年 | 6篇 |
1989年 | 10篇 |
1988年 | 11篇 |
1987年 | 3篇 |
1986年 | 6篇 |
1985年 | 6篇 |
1984年 | 2篇 |
1983年 | 2篇 |
1982年 | 2篇 |
1981年 | 3篇 |
1980年 | 2篇 |
1979年 | 5篇 |
1977年 | 2篇 |
1976年 | 2篇 |
1974年 | 4篇 |
1973年 | 1篇 |
排序方式: 共有1307条查询结果,搜索用时 256 毫秒
11.
Tsutomu Gomi Kichirou Koshida Tosiaki Miyati Jun Miyagawa Hiroshi Hirano 《Journal of digital imaging》2006,19(4):362-370
The purpose of this work was to compare direct and indirect detectors in terms of their system linearity, presampled modulation
transfer function (MTF), Wiener spectrum (WS), noise equivalent quanta (NEQ), and power spectrum. Measurements were made on
two flat-panel detectors, GE Revolution XR/d (indirect) and Shimadzu Safire (direct) radiographic techniques. The system linearity
of the systems was measured using a time-scale method. The MTF of the systems was measured using an edge method. The WS of
the systems was determined for a variable range of exposure levels by two-dimensional Fourier analysis. The NEQ was assessed
from the measured MTF, WS, and estimated ideal signal-to-noise ratios. Power spectrum analyzed the chest phantom within artificial
lesions. System linearity was excellent for the direct systems. For the direct system, the MTF was found to be significantly
higher than that for the indirect systems. For the direct system, the WS was relatively uniform across all frequencies. In
comparison, the indirect system exhibited a drop in the WS at high frequencies. At lower frequencies, the NEQ for the indirect
system was noticeably higher than for the direct system. Power spectrum for the direct system was relatively flat and similar
to that for white noise. The indirect system exhibited significant reduction at high spatial frequencies. In general, the
direct systems exhibit improved image quality over indirect systems at comparable exposure dose. 相似文献
12.
Paolo Cerretelli Pietro Enrico di Prampero 《Pflügers Archiv : European journal of physiology》1988,412(3):270-276
Frog (Rana esculenta, L.) gastrocnemii (161 pairs) or sartorii (8 pairs) were stimulated by intermittent tetani at 10°C (20 Hz, supramaximal intensity, N2 atmosphere) isometrically (IM) or isotonically (IT) for various durations (6–30 s) at different tensions (0.05–1.00 P0=maximal IM tension at resting length,l
o). The energy expenditure (E) was measured from ATP and phosphocreatine breakdown and the high energy phosphate equivalent of lactic acid production. Both in IM and IT conditions,E was found to be a linear function of the summated tetanus duration (t):E=a+b t, whereb is the energy cost of tension maintenance. For the gastrocnemius, both in IM and IT,b was independent of the tension developed and equal to 0.45 mol P · g–1 · s–1, whereas for the sartoriusb was tension-dependent, varying between 0.58 and 0.28 mol P · g–1 · s–1 for P0 and 0.18 P0, respectively. The constancy of theb value in muscles with pennate structure may be tentatively attributed, at least in part, to the greater internal energy dissipation, regardless of the tension developed. The terma of the above equation is due to all time-independent processes of muscle contraction, i.e.: (1) activation energy; (2) internal work and (3) external work (in IT only). Based on the measured value ofa and on the work performed, the mechanical equivalent of P splitting was calculated as 17.7 kJ · mol–1, a figure close to that previously obtained on frog sartorius (16.7 kJ · mol–1) and dog gastrocnemius (19.2 kJ · mol–1) When taking into account the energy due to the activation processes, the calculated net mechanical equivalent of P splitting amounted to 25.5 kJ · mol–1. 相似文献
13.
《The Foot》2021
IntroductionThe repair of a deltoid ligament injury, following an ankle fracture with involvement of the syndesmosis, has no univocal consensus. Also the surgical strategies in case of a subsequent chronic instability are still under debate. In this work the result of a double bundle anatomic reconstruction of deltoid ligament with ipsilateral autologous gracilis muscle tendon is presented.Case reportA 50 year old active male patient came to our attention with a catastrophic medial ankle instability, a severe pronation of the hindfoot and disabling ankle pain. He reported a Weber type B fracture of the left ankle with a lesion of the syndesmosis treated with anatomic plate and screws and a transyndesmotic screw 8 months before. The imaging showed a complete deltoid ligament lesion. Due to the impossibility of a direct repair of the ligament, we performed the reconstruction of the medial ligamentous complex with an autologous gracilis tendon graft. 10 months after the medial ligamentous complex reconstruction, the patient showed an excellent recovery of walking ability, disappearance of pain under load and resumed an active lifestyle.DiscussionThe deltoid ligament has a key role in ankle joint stability and its integrity promotes the recovery after ankle fractures. However, its lesion is often left untreated in the acute setting. The result of a chronic untreated deltoid ligament injury could be extremely disabling and the ligament reconstruction, when an optimal native deltoid ligament repair is not achievable, is the choice to restore ankle function and stability.ConclusionIn the delayed treatment of a deltoid ligament rupture the described double bundle anatomic reconstruction with autologous tendon graft can be an effective and suitable option. 相似文献
14.
Juxta-articular hemangioma of long bone 总被引:1,自引:0,他引:1
We report on a rare case of an intraosseous hemangioma involving the proximal tibia in a 70-year-old man. Radiographically,
the lesion was a well-defined osteolytic lesion with marginal sclerosis. The CT images demonstrated a well-defined osteolytic
lesion with partial cortical breakthrough. T1-weighted MR images showed a hypointense lesion, while T2-weighted images revealed
hyperintense areas, with internal, hypointense septa. Gadolinium-enhanced T1-weighted images showed lattice-like enhancement
of the lesion.
Received: 28 December 1999 Revision requested: 3 March 2000 Revision received: 23 May 2000 Accepted: 26 May 2000 相似文献
15.
Until recently, cardiorespiratory fitness (CRF) has been overlooked as a potential modifier of the inverse association between obesity and mortality (the so-called obesity paradox), observed in patients with known or suspected cardiovascular (CV) disease. Evidence from five observational cohort studies of 30,104 patients (87% male) with CV disease indicates that CRF significantly alters the obesity paradox. There is general agreement across studies that the obesity paradox persists among patients with low CRF, regardless of whether adiposity is assessed by body mass index, waist circumference, or percentage body fat. However, among patients with high CRF, risk of all-cause mortality is lowest for the overweight category in some, but not all, studies, suggesting that higher levels of fitness may modify the relationship between body fatness and survival in patients manifesting an obesity paradox. Further study is needed to better characterize the joint contribution of CRF and obesity on mortality in diverse populations. 相似文献
16.
Philip T. Ives 《International journal of radiation biology》2013,89(1):54-67
SummaryOregon-R males were tested in day-by-day sperm samples for dominant visible and hemizygous sex-linked mutations, fecundity (number of offspring produced), and crossing-over after exposure to cobalt-60 γ in the 100 r to 10 kr range. Tests totalled 42 184 X-chromosomes and 210 111 flies. Mutations were most frequent after irradiation during meiosis and spermiogenesis in low doses. Only sperm and gonial cells subsequently produced adult flies after exposure to 5 kr and 10 kr. After 500 r fecundity was reduced chiefly in cells in late mitosis, and in earlier and later stages with increasing doses. Reduced fecundity may not be due to the kind of mutation detected here, but both effects may combine to influence the frequency of mutations recovered, particularly from irradiated meiotic and spermiogenic cells. Males receiving 500 r might contribute more mutations to a population's gene pool than competing males after a substantially higher dose. 相似文献
17.
《Journal of food composition and analysis》2014,34(2):216-219
The main goal of this paper is to discuss the problems associated with antioxidant profiling in complex samples using a high-throughput HPLC system coupled with post-column derivatisation reactor. Based on the experimental data reported in the literature, we demonstrated that improper optimisation of temperature and/or pH assay conditions performed using an on-line derivatisation reactor may substantially change the antioxidant peaks ratio of targeted phytochemical compounds. It has been found that despite the relatively high stability of flavonoids at high temperature and under binary mobile phase HPLC conditions, the reaction of target compounds with common ABTS, FCR and DPPH radicals at elevated regions (particularly above 100 °C) dramatically changes their antioxidant activity values expressed, for example, as TEAC (Trolox equivalent antioxidant capacity) parameters. In principle, separation and detection processes of antioxidant profiling assay must not significantly affect the antioxidant activity of target compounds. In the case of foods eaten by humans or animals, critical experimental parameters such as pH and temperature concerning interaction of target analytes with derivatisation reagent should be as close as possible to the real physiological values. 相似文献
18.
Isabele Rejane de Oliveira Maranhão Pureza André Eduardo da Silva Junior Dafiny Rodrigues Silva Praxedes Laís Gomes Lessa Vasconcelos Mateus de Lima Macena Ingrid Sofia Vieira de Melo Telma Maria de Menezes Toledo Florêncio Nassib Bezerra Bueno 《Clinical nutrition (Edinburgh, Scotland)》2021,40(3):759-766
19.
《Sleep medicine》2020
BackgroundMost Parkinson's patients suffered from sleep problems. There is increasing evidence that Subthalamic Nucleus Deep Brain Stimulation (STN-DBS) has a positive effect on several sleep parameters, improving overall sleep quality in patients with PD. However, the results are controversial.MethodsWe performed a retrospective study and meta-analysis to assess the Parkinson's disease sleep scale (PDSS) in Parkinson's patients.ResultsWe reviewed our data of patients who underwent STN-DBS, and then extracted five other trials to perform a meta-analysis. The pooled results showed an advantage on post-operative PDSS in both our medical center and pooled results (MD = 20.41, 95% CI = [13.03, 27.79], I2 = 61%, P < 0.001). There was a significant difference in Unified Parkinson's Disease Rating Scale (UPDRS)-Ⅲ score between pre and post-operation (MD = −12.59, 95% CI = [−14.70, −10.49], I2 = 90%, P < 0.001). What's more, Parkinsonian medication was significantly lower in the post-operative groups after DBS (MD = −314.71, 95% CI = [−468.13, −161.28], I2 = 53%, P < 0.001).ConclusionIn the retrospective study and meta-analysis of 6 trials, we found that DBS can significantly increase sleep quality. Furthermore, motor function improved and Parkinsonian medication was significantly decreased postoperatively. The sample size was enough and no further investigations would change the conclusion. 相似文献
20.
《Journal of vascular and interventional radiology : JVIR》2021,32(8):1103-1112.e12
PurposeTo investigate the feasibility, safety, and absorbed-dose distribution of prostatic artery radioembolization (RE) in a canine model.Materials and MethodsFourteen male castrated beagles received dihydroandrosterone/estradiol to induce prostatic hyperplasia for the duration of the study. Each dog underwent fluoroscopic prostatic artery catheterization. Yttrium-90 (90Y) microspheres (TheraSphere; Boston Scientific, Marlborough, Massachusetts) were delivered to 1 prostatic hemigland (dose escalation from 60 to 200 Gy), with the contralateral side serving as a control. Assessments for adverse events were performed throughout the follow-up (Common Terminology Criteria for Adverse Events v5.0). Positron emission tomography/magnetic resonance (MR) imaging provided a confirmation after the delivery of absorbed-dose distribution. MR imaging was performed before and 3, 20, and 40 days after RE. Tissue harvest of the prostate, rectum, bladder, urethra, penis, and neurovascular bundles was performed 60 days after RE.ResultsAll the animals successfully underwent RE. Positron emission tomography/MR imaging demonstrated localization to and good coverage of only the treated hemigland. No adverse events occurred. The MR imaging showed a significant dose-dependent decrease in the treated hemigland size at 40 days (25%–60%, P < .001). No extraprostatic radiographic changes were observed. Necropsy demonstrated no gross rectal, urethral, penile, or bladder changes. Histology revealed RE-induced changes in the treated prostatic tissues of the highest dose group, with gland atrophy and focal necrosis. No extraprostatic RE-related histologic findings were observed.ConclusionsProstate 90Y RE is safe and feasible in a canine model and leads to focal dose-dependent changes in the gland without inducing unwanted extraprostatic effects. These results suggest that an investigation of nonoperative prostate cancer is warranted. 相似文献