全文获取类型
收费全文 | 2795篇 |
免费 | 167篇 |
国内免费 | 5篇 |
专业分类
耳鼻咽喉 | 30篇 |
儿科学 | 111篇 |
妇产科学 | 37篇 |
基础医学 | 316篇 |
口腔科学 | 50篇 |
临床医学 | 231篇 |
内科学 | 629篇 |
皮肤病学 | 49篇 |
神经病学 | 154篇 |
特种医学 | 103篇 |
外科学 | 438篇 |
综合类 | 55篇 |
一般理论 | 1篇 |
预防医学 | 148篇 |
眼科学 | 169篇 |
药学 | 220篇 |
中国医学 | 8篇 |
肿瘤学 | 218篇 |
出版年
2023年 | 19篇 |
2022年 | 79篇 |
2021年 | 140篇 |
2020年 | 70篇 |
2019年 | 86篇 |
2018年 | 99篇 |
2017年 | 64篇 |
2016年 | 74篇 |
2015年 | 92篇 |
2014年 | 123篇 |
2013年 | 159篇 |
2012年 | 212篇 |
2011年 | 217篇 |
2010年 | 116篇 |
2009年 | 88篇 |
2008年 | 144篇 |
2007年 | 156篇 |
2006年 | 141篇 |
2005年 | 134篇 |
2004年 | 99篇 |
2003年 | 98篇 |
2002年 | 79篇 |
2001年 | 59篇 |
2000年 | 47篇 |
1999年 | 48篇 |
1998年 | 16篇 |
1997年 | 17篇 |
1996年 | 12篇 |
1995年 | 12篇 |
1993年 | 9篇 |
1992年 | 23篇 |
1991年 | 13篇 |
1990年 | 14篇 |
1989年 | 20篇 |
1988年 | 8篇 |
1987年 | 15篇 |
1986年 | 21篇 |
1985年 | 15篇 |
1984年 | 12篇 |
1983年 | 8篇 |
1982年 | 6篇 |
1978年 | 6篇 |
1977年 | 5篇 |
1976年 | 5篇 |
1975年 | 8篇 |
1974年 | 7篇 |
1973年 | 9篇 |
1972年 | 15篇 |
1971年 | 7篇 |
1969年 | 5篇 |
排序方式: 共有2967条查询结果,搜索用时 39 毫秒
1.
2.
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
3.
Rajesh Venkataraman Karthik R. Vaidyanathan Madhu N. Sankar Kotturathu M. Cherian 《Journal of cardiac surgery》2009,24(4):443-445
Abstract Dissection of the pulmonary autograft is an extremely rare complication requiring emergent treatment as there is a chance of rupture and proximal aortic involvement. The autograft dissection can involve the aortic annulus, causing separation of leaflets from the annulus in addition to causing annular dilatation, thereby precluding resuspension of leaflets. The usual treatment in such cases is to perform the Bentall procedure, which involves placing a valved conduit (usually mechanical valve) and thereby necessitating anticoagulation. This report describes a case of successful valve-sparing aortic root replacement following the Ross procedure with dissection of autograft. 相似文献
4.
Mozammil Hussain Raghu N. Natarajan Amir H. Fayyazi Brian R. Braaksma Gunnar B.J. Andersson Howard S. An 《The spine journal》2009,9(12):1016-1023
Background contextAnterior corpectomy and reconstruction with bone graft and a rigid screw-plate construct is an established procedure for treatment of cervical neural compression. Despite its reliability in relieving symptoms, there is a high rate of construct failure, especially in multilevel cases.PurposeThere has been no study evaluating the biomechanical effects of screw angulation on construct stability; this study investigates the C4–C7 construct stability and load-sharing properties among varying screw angulations in a rigid plate-screw construct.Study designA finite element model of a two-level cervical corpectomy with static anterior cervical plate.MethodsA three-dimensional finite element (FE) model of an intact C3–T1 segment was developed and validated. From this intact model, a fusion model (two-level [C5, C6] anterior corpectomy) was developed and validated. After corpectomy, allograft interbody fusion with a rigid anterior screw-plate construct was created from C4 to C7. Five additional FE models were developed from the fusion model corresponding to five different combinations of screw angulations within the vertebral bodies (C4, C7): (0°, 0°), (5°, 5°), (10°, 10°), (15°, 15°), and (15°, 0°). The fifth fusion model was termed as a hybrid fusion model.ResultsThe stability of a two-level corpectomy reconstruction is not dependent on the position of the screws. Despite the locked screw-plate interface, some degree of load sharing is transmitted to the graft. The load seen by the graft and the shear stress at the bone-screw junction is dependent on the angle of the screws with respect to the end plate. Higher stresses are seen at more divergent angles, particularly at the lower level of the construct.ConclusionThis study suggests that screw divergence from the end plates not only increases load transmission to the graft but also predisposes the screws to higher shear forces after corpectomy reconstruction. In particular, the inferior screw demonstrated larger stress than the upper-level screws. In the proposed hybrid fusion model, lower stresses on the bone graft, end plates, and bone-screw interface were recorded, inferring lower construct failure (end-plate fractures and screw pullout) potential at the inferior construct end. 相似文献
5.
Vandana Jain Supriya Dabir Debraj Shome Tina Dadu Sundaram Natarajan 《Survey of ophthalmology》2009,54(2):286
We report the case of a 25-year-old male patient who presented with complaints of redness, photophobia, and decreased vision in the right eye of a week's duration. Slit-lamp biomicroscopic examination revealed a cream-colored, irregular elevated inferior iris mass, extending on to the anterior lens surface. Differential diagnoses of a fungal granuloma, a medulloepithelioma, and an amelanotic melanoma were considered. An excisional biopsy of the mass was performed through a superior clear corneal incision. Polymerase chain reaction analysis of the aqueous humor showed a positive pan fungal genome. Histopathology of the biopsied mass showed a giant cell granuloma with surrounding numerous branching, septate hyphae. Culture growth revealed Aspergillus fumigatus We report this case because of the rarity of Aspergillus iris granuloma as a primary presentation of endogenous Aspergillosis and review the relevant literature. Absence of a significant systemic history compounded the diagnostic dilemma in our patient. Definitive differentiation of this rare entity from a foreign body, amelanotic melanoma, and other inflammatory conditions such as sarcoidosis and tuberculosis, may be possible only on microbiological and histo-pathological evaluation. 相似文献
6.
7.
8.
Chromosomal aberrations in human lymphocytes induced in vitro by very low doses of X-rays. 总被引:2,自引:0,他引:2
D C Lloyd A A Edwards A Leonard G L Deknudt L Verschaeve A T Natarajan F Darroudi G Obe F Palitti C Tanzarella 《International journal of radiation biology》1992,61(3):335-343
This paper presents results of a collaborative experiment between six laboratories which examined the yields of unstable chromosomal aberrations in human lymphocytes induced in vitro by X-rays over the dose range 0-300 mGy. The work included data points of nominal doses of 0, 3, 5, 6, 10, 20, 30, 50 and 300 mGy. Cells from 24 donors were examined and a total of about 300,000 metaphases were scored. The work was undertaken to determine the limits of sensitivity of the system taking into account variations in scoring data due to inter-donor sample and inter-laboratory effects. Despite the existence of these effects, aberration yields significantly in excess of control values were seen at doses greater than 20 mGy and these were consistent with a linear extrapolation from higher doses. Below 20 mGy the observed dicentric yields were generally lower than background, but not significantly so. Excess acentric aberrations, on the other hand, and centric rings, were higher than the controls but the increase was usually not significant. It is concluded that the statistical uncertainties are such that below 20 mGy this technique cannot distinguish between a linear or a threshold model. 相似文献
9.
A. Parthasarathy N. Sumathi R. Manoharan C. D. Natarajan R. Narmada B. R. Santhanakrishnan 《Indian journal of pediatrics》1987,54(5):779-784
Tuberculous infection among children continues to be a significant cause of morbidity. The symptom complex are so variable
among children that the final diagnosis often rests on the laboratory tests. Proper interpretation of the tests, specially
tuberculin test and radiographic studies, are necessary for establishing correct diagnosis. The usefulness of tuberculin test
in both unimmunized and BCG vaccinated children is highlighted. BCG accelerated response as a test should be reserved for
identifying serious form of pulmonary disease or CNS tuberculosis when the tuberculin test is negative. Radiographic assessment
may be sensitive in some instances but not always specific and hence needs cautious interpretation. Tuberculosis among BCG
vaccinated children though not uncommon, needs proper documentation. Current trends in the management of tuberculosis including
CNS forms are briefly outlined. 相似文献
10.