全文获取类型
收费全文 | 7158篇 |
免费 | 412篇 |
国内免费 | 20篇 |
专业分类
耳鼻咽喉 | 92篇 |
儿科学 | 225篇 |
妇产科学 | 127篇 |
基础医学 | 937篇 |
口腔科学 | 165篇 |
临床医学 | 682篇 |
内科学 | 1361篇 |
皮肤病学 | 245篇 |
神经病学 | 935篇 |
特种医学 | 254篇 |
外科学 | 804篇 |
综合类 | 39篇 |
现状与发展 | 1篇 |
一般理论 | 2篇 |
预防医学 | 659篇 |
眼科学 | 122篇 |
药学 | 391篇 |
中国医学 | 19篇 |
肿瘤学 | 530篇 |
出版年
2023年 | 50篇 |
2022年 | 105篇 |
2021年 | 180篇 |
2020年 | 132篇 |
2019年 | 175篇 |
2018年 | 190篇 |
2017年 | 137篇 |
2016年 | 187篇 |
2015年 | 180篇 |
2014年 | 277篇 |
2013年 | 319篇 |
2012年 | 488篇 |
2011年 | 479篇 |
2010年 | 281篇 |
2009年 | 290篇 |
2008年 | 389篇 |
2007年 | 403篇 |
2006年 | 409篇 |
2005年 | 396篇 |
2004年 | 349篇 |
2003年 | 310篇 |
2002年 | 275篇 |
2001年 | 108篇 |
2000年 | 134篇 |
1999年 | 115篇 |
1998年 | 62篇 |
1997年 | 53篇 |
1996年 | 61篇 |
1995年 | 38篇 |
1994年 | 36篇 |
1993年 | 30篇 |
1992年 | 68篇 |
1991年 | 85篇 |
1990年 | 76篇 |
1989年 | 56篇 |
1988年 | 77篇 |
1987年 | 67篇 |
1986年 | 44篇 |
1985年 | 56篇 |
1984年 | 52篇 |
1983年 | 24篇 |
1981年 | 16篇 |
1980年 | 17篇 |
1979年 | 28篇 |
1978年 | 18篇 |
1976年 | 20篇 |
1975年 | 23篇 |
1974年 | 28篇 |
1973年 | 14篇 |
1968年 | 13篇 |
排序方式: 共有7590条查询结果,搜索用时 0 毫秒
1.
2.
3.
Paul P. W. van Buul Iris M. Zandman Mira Grigorova Jan J. W. A. Boei Adayapalam T. Natarajan 《Chromosome research》1995,3(7):427-432
The efficiency of two methods of detection of translocations induced in mouse stem cell spermatogonia by X-ray doses of 2, 5 and 7 Gy was compared: classical multivalent analysis at diakinesis-metaphase I of meiosis and observation via fluorescencein situ hybridization analysis of mitotic or meiotic stages. Specific DNA libraries for chromosomes 1, 11 and 13 were used. The results obtained indicate that (a) chromosomes 1, 11 and 13 are more involved in multivalent formation than expected on the basis of DNA content and (b) if the mitotic FISH analysis data are corrected for the observed over-representation, the frequencies of induced translocations are similar to those recorded in the classical multivalent studies, suggesting equal scoring efficiencies in both systems. 相似文献
4.
In the present experiments we have investigated the influence of wall shear rate and axial position on platelet and fibrin deposition which results when flowing human non-anticoagulated blood is exposed to either non-procoagulant fibrillar collagen (human type III) or procoagulant subendothelium (rabbit aorta). Platelet adhesion, thrombus volume and fibrin deposition were morphometrically evaluated at axial positions of 1 and 13 mm following perfusions for 5 min at shear rates of 100, 650 and 2,600 s-1. An axially-dependent decrease of platelet adhesion (34-57%, p less than 0.01-0.05) and thrombus volume (57-80%, p less than 0.05) was observed on collagen at all shear rates. On subendothelium, an axially-dependent decrease was observed for platelet adhesion only at 100 s-1 (29%; p less than 0.01) and for thrombus volume at shear rates of 650 s-1 and above (49-58%, p less than 0.01). Deposition of fibrin on subendothelium was axially decreased (16-42%, p less than 0.05) at all shear rates, while no significant axial differences were seen on collagen. However, substantially more fibrin was deposited on the subendothelium (p less than 0.05), and the upstream platelet adhesion and thrombus volume were lower than on collagen (p less than 0.05) at 100 s-1 and 650 s-1. The axially-dependent phenomena on the two surfaces are consistent with the concept of rapid-growing upstream thrombi which deplete the blood layer streaming adjacent ot the surface of platelets, leading to decreased platelet deposition further downstream.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
5.
N Diehm A Shang A Silvestro D-D Do F Dick J Schmidli F Mahler I Baumgartner 《European journal of vascular and endovascular surgery》2006,31(1):59-63
OBJECTIVES: Aim of this study is to correlate distribution pattern of lower limb atherosclerosis with cardiovascular risk factor profile of patients with peripheral arterial occlusive disease (PAD). PATIENTS AND METHODS: Analysis is based on a consecutive series of 2659 patients (1583 men, 1076 women, 70+/-11 years) with chronic PAD of atherosclerotic origin undergoing primary endovascular treatment of lower extremity arteries. Pattern of atherosclerosis was grouped into iliac (n=1166), femoropopliteal (n=2151) and infrageniculate (n=888) disease defined according to target lesions treated. A multivariable multinomial logistic regression analysis was performed to assess relation with age, gender and classical cardiovascular risk factors (diabetes mellitus, arterial hypertension, hypercholesterolemia, cigarette smoking) using femoropopliteal disease as reference. RESULTS: Iliac disease was associated with younger age (RRR 0.95 per year of age, 95%-CI 0.94-0.96, p<0.001), male gender (RRR 1.32, 95%-CI 1.09-1.59, p=0.004) and cigarette smoking (RRR 2.02, 95%-CI 1.68-2.42, p<0.001). Infrageniculate disease was associated with higher age (RRR 1.02, 95%-CI 1.01-1.02, p<0.001), male gender (RRR 1.23, 95%-CI 1.06-1.41, p=0.005) and diabetes mellitus (RRR 1.68, 95%-CI 1.47-1.92, p<0.001). Hypercholesterolemia was less prevalent in patients with lesions below the knee (RRR 0.82, 95%-CI 0.71-0.94, p=0.006), whereas no distinct pattern was apparent related to arterial hypertension. CONCLUSION: Clinical phenotype of peripheral atherosclerosis varies with prevalence of cardiovascular risk factors suggesting differences in mechanisms involved in iliac as compared with infrageniculate lesions. Identification of molecular mechanism might have influence on future therapeutic strategies in PAD patients. 相似文献
6.
7.
8.
C Baumgartner W W Sutherling S Di D S Barth 《Electroencephalography and clinical neurophysiology》1991,79(1):27-35
We measured somatosensory evoked magnetic fields during median nerve stimulation in 6 normal subjects. We applied multiple dipole models to study the spatiotemporal structure of early somatosensory evoked magnetic fields (SEFs), as well as the number, 3-dimensional location and time activity of their underlying neuronal sources. Two dipole sources were necessary to model the first 40 msec of SEFs explaining 85% of the data variance. Source 1 was located deeper than source 2, showed primarily a tangential orientation, and accounted for a larger part of the variance; source 2 showed no consistent orientation across subjects. Both sources showed biphasic time activities corresponding to the previously described N20-P30 and P25-N35 components. Spatiotemporal modeling could identify sources which could not be modeled consistently above noise by single moving dipoles (P25 component), revealed small latency differences of the two sources in some subjects suggesting parallel activation of these sources, and allowed separation of sources overlapping considerably both in space and time. We conclude that spatiotemporal modeling of SEFs may be useful to study functional anatomy of human sensorimotor cortex non-invasively. 相似文献
9.
New indole alkaloid glycosides from Nauclea orientalis 总被引:4,自引:0,他引:4
Two new indole alkaloid glycosides, 10-hydroxystrictosamide and 6'-O-acetylstrictosamide, as well as the known alkaloids strictosamide and vincosamide were isolated from the leaves of Nauclea orientalis L. The structures of the isolated compounds were determined using spectroscopic methods, mainly 1D- and 2D-NMR spectroscopy. 相似文献
10.
Thirty-four patients with atlanto-axial instability due to rheumatoid arthritis were examined with plain x-ray views and functional magnetic resonance imaging (MR), and were neurologically evaluated. Transcranial brain stimulation was performed in 25 patients. In 22 cases, the authors observed inflammatory tissue thicker than 3 mm behind the odontoid peg. The spinal canal diameter was significantly decreased in the flexed position. Nine patients showed signs of cranial migration of the axis. The diameter of the spinal cord was measured to be 7.4 mm in the neutral position, and 6.5 mm in flexion. The difference between the diameter of the neutral and flexed positions was highly significant. Twelve of the 34 patients displayed clinical signs of cervical myelopathy, and 13 showed a significant delay of central motor latency, as calculated from the motor evoked potentials. Surgical intervention, either by a posterior approach only or combined with a transoral dens and inflammatory tissue resection, is recommended in patients with progressive atlanto-axial instability, pathologic clinical and neurophysiologic findings, and a spinal cord diameter of less than 6 mm in flexion. Severe pain and cranial migration of the axis, as measured by the MRI, also justify a surgical intervention. 相似文献