全文获取类型
收费全文 | 45577篇 |
免费 | 3275篇 |
国内免费 | 160篇 |
专业分类
耳鼻咽喉 | 663篇 |
儿科学 | 1214篇 |
妇产科学 | 790篇 |
基础医学 | 6000篇 |
口腔科学 | 579篇 |
临床医学 | 4680篇 |
内科学 | 9628篇 |
皮肤病学 | 491篇 |
神经病学 | 4378篇 |
特种医学 | 1670篇 |
外科学 | 7578篇 |
综合类 | 839篇 |
现状与发展 | 1篇 |
一般理论 | 40篇 |
预防医学 | 3569篇 |
眼科学 | 588篇 |
药学 | 3107篇 |
中国医学 | 58篇 |
肿瘤学 | 3139篇 |
出版年
2023年 | 268篇 |
2022年 | 510篇 |
2021年 | 1164篇 |
2020年 | 658篇 |
2019年 | 1073篇 |
2018年 | 1295篇 |
2017年 | 871篇 |
2016年 | 1021篇 |
2015年 | 1237篇 |
2014年 | 1630篇 |
2013年 | 2161篇 |
2012年 | 3598篇 |
2011年 | 3665篇 |
2010年 | 2034篇 |
2009年 | 1823篇 |
2008年 | 3049篇 |
2007年 | 3125篇 |
2006年 | 3046篇 |
2005年 | 3084篇 |
2004年 | 2752篇 |
2003年 | 2606篇 |
2002年 | 2362篇 |
2001年 | 401篇 |
2000年 | 281篇 |
1999年 | 381篇 |
1998年 | 487篇 |
1997年 | 423篇 |
1996年 | 350篇 |
1995年 | 336篇 |
1994年 | 289篇 |
1993年 | 263篇 |
1992年 | 232篇 |
1991年 | 199篇 |
1990年 | 179篇 |
1989年 | 172篇 |
1988年 | 161篇 |
1987年 | 137篇 |
1986年 | 129篇 |
1985年 | 122篇 |
1984年 | 135篇 |
1983年 | 113篇 |
1982年 | 146篇 |
1981年 | 152篇 |
1980年 | 106篇 |
1979年 | 74篇 |
1978年 | 72篇 |
1977年 | 71篇 |
1976年 | 60篇 |
1975年 | 54篇 |
1973年 | 57篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
52.
Richard Sacknoff M.D. Robert A. Novelline M.D. James T. Rhea M.D. J. Nash Lawrason M.D. Patrick M. Rao M.D. 《Emergency radiology》1997,4(2):109-111
A 36-year-old man was brought to the emergency department after being assaulted. A mandible series showed a nondisplaced fracture through the angle of the mandible extending through the left third molar tooth. Axial slices from a nonhelical computed tomographic (CT) examination of the head as well as a helical CT examination of the mandible failed to demonstrate the fracture. The fracture was well shown, however, on sagittal CT reformations. Although CT is generally regarded as more sensitive than plain radiography for the detection of fractures, fractures may be overlooked by CT if examination in only one plane is performed. 相似文献
53.
Didier Chatel Laurent Delamare Patrick Dang Daniel Lebouvier Franqois Trocherie 《Artificial organs》1997,21(10):1098-1104
Abstract: For original ovoid shaped artificial ventricles. a biomechanical double sac consisting of a biological sac (porcine pericardium) as the blood contact interface and a synthetic sac (Pebax 3533) as the mechanical support to assume systolic-diastolic dynamic constraints was conceived. The volumetric and mechanical properties were assessed with a three-dimensional modeling of Pebax sacs and computerized simulations of their systolic distortions for both right and left ventricular configurations. The stresses and strains of these sacs were represented as quantitative mappings for a maximum end-systolic state and were below the respective threshold values above which the Pebax material is jeopardized for permanent structure impairment. After fatigue tests applied on Pebax strips under the alleged working conditions of Pebax sacs, the material structure was unchanged and maintained its intrinsic mechanical properties. The theoretical maximum stroke volumes were 74.4 cm3 and 62.4 cm for the left and right ventricular configurations, respectively. With these mechanical and volumetric features, the biomechanical double sac concept was considered valid and could be provided for a consequent specific total artificial heart. 相似文献
54.
Patrick M. Rao M.D. James T. Rhea M.D. Robert A. Novelline M.D. 《Emergency radiology》1997,4(5):268-275
This article reviews a focused helical appendiceal computed tomographic technique and discusses an approach to appendiceal computed tomographic interpretation. 相似文献
55.
56.
Calis Sema Jeyanthi Ramasubbu Tsai Tsuimin Mehta Rahul C. DeLuca Patrick P. 《Pharmaceutical research》1995,12(7):1072-1076
Purpose. The interaction of salmon calcitonin (sCT) and poly (d,l-lactide-co-glycolide) was detected during preparation and evaluation of microspheres. The purpose of this study was to quantitate the extent and nature of the interaction.
Methods. Blank microspheres were prepared by an aqueous emulsification solvent extraction technique. Adsorption studies were carried out at six concentrations of sCT and three concentrations of microspheres. Adsorption isotherms were constructed using the Langmuir and Freundlich treatments.
Results. Adsorption at 1 mg/ml sCT concentration resulted in almost complete depletion of the peptide from the adsorption medium with the time to reach maximum adsorption decreasing with increasing microsphere concentration. At sCT concentrations below 100 µg/ml, a true equilibrium occurred in 1 hour or less while at higher concentrations (up to 350 µg/ml), a transient equilibrium was reached in 1 to 2 hours, followed by further adsorption of the peptide. The adsorption followed the Langmuir isotherm at concentrations below 200 µg/ml, indicating formation of a monolayer. Multilayer interaction, described by the Freundlich isotherm, occurred at higher concentrations and resulted in complete depletion of sCT from the adsorption medium. The affinity constant during monolayer formation was 0.09 and the plateau surface concentration was 5.1 µg/mg. The multilayer peptide-peptide adsorption showed a lower affinity (0.025) but higher capacity (24 µg/mg) than the monolayer peptide-polymer adsorption.
Conclusions. The results show that poly (d,l-lactide-co-glycolide) microspheres have a high adsorption capacity for sCT which must be considered in formulating a controlled delivery product of this peptide. 相似文献
57.
Shearwood McClelland Patrick B Senatus Blair Ford Guy M McKhann Robert R Goodman 《Journal of clinical neuroscience》2007,14(8):791-793
Deep brain stimulation (DBS) for medically intractable Parkinson's disease (PD) is well established, but carries the inconveniences of frame-based neurosurgery. Previous reports have demonstrated that ventricular shunt placement and some functional procedures can be accurately performed using frameless stereotaxy. We present a report indicating that staged deep brain electrode placement can be accurate and efficacious using a frameless skull-mounted guide. 相似文献
58.
Editorial comment 总被引:2,自引:0,他引:2
Ronald Dubner Howard L. Fields Gerald F. Gebhart John D. Loeser Harold Merskey Patrick D. Wall 《Pain》1992,50(3):247-248
59.
60.
Zvi Bar-Shavit Ronald L. Horst Jean C. Chappel F. Patrick Ross Richard W. Gray Steven L. Teitelbaum M.D. 《Calcified tissue international》1986,39(5):328-333
Summary 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) is a potent inducer of monocytic differentiation of the human promyelocytic leukemia cell line, HL-60. We have noted that
25-hydroxyvitamin D3 (25(OH)D3) in high doses is also capable of promoting monocytic differentiation of this cell line. To test the possibility that the
latter activity is due to conversion of 25OHD3 to 1,25(OH)2D3 by HL-60, we exposed HL-60 cells to 25OHD3 and analyzed the products by HPLC and radioreceptor assay. When chromatographed in the traditional solvent system (isopropanol-hexane),
a new peak appears which migrates with authentic 1,25(OH)2D3. However, in a solvent system containing dichloromethane, 90% of the peak migrates with another metabolite, 19-Nor-10-Keto-25OHD3 (19-Nor-25OHD3). Production of this metabolite is enhanced by living cells and is synthesized by both virgin HL-60 and those which have
undergone differentiation. We next determined if authentic 19-Nor-25OHD3 also promotes differentiation of this cell. As assessed by appearance of the monocyte-specific surface antigen (63D3) and
macrophage-specific esterase activity, we find that this metabolite does, in fact, induce monocytic differentiation of HL-60
with a potency of approximately 1/200 that of 1,25(OH)2D3 and similar to that of 25OHD3. In agreement with the effect upon cell maturation, 19-Nor-25OHD3 displaces3H-1,25(OH)2D3 from its HL-60 receptor with an efficiency comparable to 25OHD3. Hence, HL-60 cells convert 25OHD3 to 19-Nor-25OHD3, and 19-Nor-25OHD3 induces monocytic differentiation of HL-60 with comparable efficiency to its precursor, 25OHD3. 相似文献