全文获取类型
收费全文 | 1166769篇 |
免费 | 76338篇 |
国内免费 | 1494篇 |
专业分类
耳鼻咽喉 | 16461篇 |
儿科学 | 38755篇 |
妇产科学 | 31802篇 |
基础医学 | 166012篇 |
口腔科学 | 31922篇 |
临床医学 | 101513篇 |
内科学 | 220907篇 |
皮肤病学 | 27058篇 |
神经病学 | 88393篇 |
特种医学 | 46911篇 |
外国民族医学 | 232篇 |
外科学 | 178528篇 |
综合类 | 22958篇 |
现状与发展 | 1篇 |
一般理论 | 286篇 |
预防医学 | 79347篇 |
眼科学 | 27242篇 |
药学 | 92323篇 |
7篇 | |
中国医学 | 3055篇 |
肿瘤学 | 70888篇 |
出版年
2018年 | 11959篇 |
2017年 | 9494篇 |
2016年 | 10903篇 |
2015年 | 12210篇 |
2014年 | 16503篇 |
2013年 | 24106篇 |
2012年 | 32970篇 |
2011年 | 34735篇 |
2010年 | 20519篇 |
2009年 | 19324篇 |
2008年 | 32482篇 |
2007年 | 34862篇 |
2006年 | 35553篇 |
2005年 | 34003篇 |
2004年 | 32631篇 |
2003年 | 31322篇 |
2002年 | 30270篇 |
2001年 | 65227篇 |
2000年 | 66668篇 |
1999年 | 55285篇 |
1998年 | 13686篇 |
1997年 | 12196篇 |
1996年 | 12048篇 |
1995年 | 11268篇 |
1994年 | 10217篇 |
1993年 | 9737篇 |
1992年 | 40737篇 |
1991年 | 39097篇 |
1990年 | 38543篇 |
1989年 | 36946篇 |
1988年 | 33227篇 |
1987年 | 32340篇 |
1986年 | 30491篇 |
1985年 | 28600篇 |
1984年 | 20768篇 |
1983年 | 17416篇 |
1982年 | 9591篇 |
1981年 | 8407篇 |
1979年 | 18504篇 |
1978年 | 12514篇 |
1977年 | 11145篇 |
1976年 | 9623篇 |
1975年 | 11051篇 |
1974年 | 12667篇 |
1973年 | 12269篇 |
1972年 | 11616篇 |
1971年 | 10905篇 |
1970年 | 9970篇 |
1969年 | 9619篇 |
1968年 | 8555篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
81.
The influence of short‐term confinement and moderate exercise on tibia development was investigated in growing pigs (36–41 kg, 10 weeks at the beginning of the study). Animals were kept for 2 weeks either in individual crates of 0.8 m2 (‘confinement’, n = 4) or kept in groups of four animals in large crates of 5.6 m2 without (‘control’) or with additional exercise (30 min walking at 5 days/week; ‘exercise’). Bone density and morphological parameters were evaluated by computer tomography (CT). Periosteal apposition and longitudinal growth were determined after polychrome sequential labelling in weekly intervals. Cortical areas of the cross sections at the mid‐shaft and at 75% of the length of the bone measured distal to the carpus by CT were significantly correlated to each other (r = 0.70) and revealed a significant reduction in confined animals. This difference was explained by lower periosteal apposition rates in these animals compared with exercised and group‐housed pigs. Similarly longitudinal growth and the formation and calcification of spongiosa of the tibiae were inhibited by confinement. Thus, 2 weeks of confinement led to significant differences in bone growth and metabolism in young growing piglets when compared with animals with moderate activity. 相似文献
82.
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
83.
F Piccione F Giorgi P Tonin K Priftis S Giove S Silvoni G Palmas F Beverina 《Clinical neurophysiology》2006,117(3):531-537
OBJECTIVE: This study aimed to describe the use of the P300 event-related potential as a control signal in a brain computer interface (BCI) for healthy and paralysed participants. METHODS: The experimental device used the P300 wave to control the movement of an object on a graphical interface. Visual stimuli, consisting of four arrows (up, right, down, left) were randomly presented in peripheral positions on the screen. Participants were instructed to recognize only the arrow indicating a specific direction for an object to move. P300 epochs, synchronized with the stimulus, were analyzed on-line via Independent Component Analysis (ICA) with subsequent feature extraction and classification by using a neural network. RESULTS: We tested the reliability and the performance of the system in real-time. The system needed a short training period to allow task completion and reached good performance. Nonetheless, severely impaired patients had lower performance than healthy participants. CONCLUSIONS: The proposed system is effective for use with healthy participants, whereas further research is needed before it can be used with locked-in syndrome patients. SIGNIFICANCE: The P300-based BCI described can reliably control, in 'real time', the motion of a cursor on a graphical interface, and no time-consuming training is needed in order to test possible applications for motor-impaired patients. 相似文献
84.
85.
M Engelhardt P Bast N Jeblink W Lauer A Popovic H Eufinger M Scholz A Christmann A Harders K Radermacher K Schmieder 《Minimally invasive neurosurgery》2006,49(2):98-103
This study was performed to evaluate the surgical strategy in patients with calvarial tumours, in order to design and modify a robot-assisted trepanation system. A total of 75 patients underwent craniectomy for the treatment of calvarial tumours during the 10-year period from 1993 to 2002. The patients' complaints, the size, location and histology of the tumour, and the various cranioplasty techniques used were analysed retrospectively. In a second procedure several craniectomies at typical locations according to the study's results were performed in a laboratory setting using a hexapod robotic tool, constructed at the Helmholtz-Institute, RWTH Aachen University, and plastic model heads. The workflow was documented and the reproducibility and the accuracy of the procedure were registered. A total of 83 surgical procedures were performed on 75 patients. The majority (87 %) of lesions treated surgically were located in the frontal, temporal and anterior parts of the parietal region. Histological examination revealed benign lesions in 66 % of the patients and dural involvement in 46 %. According to these results craniectomies were performed using the robotic system. Mean positioning accuracy of the robotic system while milling was 0.24 mm, with a standard deviation of 0.04 mm, and maximum error under 1 mm. Craniectomies leaving a 1-mm layer of the tabula interna intact to ensure a healthy dura were performed in several regions successfully. The majority of calvarial tumours, requiring surgical treatment in our patients, were located in cosmetically relevant areas in which drilling can be carried out with the robotic trepanation system. Consequently, the surgical approach had to be planned carefully in order to achieve a good cosmetic outcome. 相似文献
86.
87.
88.
目的:直肠腺瘤和其他疑似为良性的病变应用经肛门内镜切除术并未普及。该项研究旨在评估经肛门内镜切除术的效能和安全性。方法:回顾性研究分析在1993-2004年之间3所斯德哥尔摩医院中经肛门内镜切除术的患,内容包括患自身及病变特性、并发症、随访时间和复发率。结果:180例中共131例行经肛门内镜切除术。160例经组织学诊断为腺瘤,12例为癌瘤,其余8例分别为增生、纤维化或正常黏膜。直肠腺瘤患中,77例仅行单次经肛门内镜切除术,16例因巨大腺瘤而多次行该手术,27例因复发而需另行经肛门内镜切除术或其他手术。中位复发时间为7个月,但未出现直肠癌。16例手术患出现并发症。2例患必须行Hartman手术,1例因肠穿孔,另1例因出血。手术期间无死亡。未复发的中位随访期为32个月(极差0—67)。[编按] 相似文献
89.
90.
Four clinical trials of porcine islet transplantation have been reported, and there are verbal reports that clinical trials on much larger scales are continuing in centers in China and Russia. The four reported trials are briefly reviewed and, in the light of the present status of experimental islet xenotransplantation, consideration is given to whether such trials are currently justified. The Ethics Committee of the International Xenotransplantation Association has (1) emphasized the need for encouraging studies in non-human primates before clinical trials should be undertaken, (2) mandatory monitoring for the transfer of porcine microorganisms, and (3) careful regulation and oversight by recognized bodies. Other aspects of the topic, such as the need for informed consent, are briefly discussed. We conclude that, at the present time, more data documenting convincing efficacy, focused on clinically applicable immunosuppressive regimens, are needed to justify the initiation of closely monitored clinical trials. A clinical trial may then be justified even though the potential risk to the patients, and possibly for society, will not be zero. 相似文献