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991.
992.
目的:研究腭穹隆形态对上颌全口义齿基托位移的影响。方法:模拟5种咬合状态,对尖、平、凹3种腭穹隆形态的上颌全口义齿的三维有限元模型进行加载。结果:3种腭穹隆形态上颌全口义齿基托在5种加载方式下,凹型腭穹隆形态基托的上腭前部及后缘区向黏膜组织的下压位移最大,基托边缘封闭区背离黏膜组织的位移最小。基托的位移方式因加载方式不同而不同。结论:上颌全口义齿基托位移方式及大小与加载方式有关;腭穹隆形态对上颌全口义齿基托位移方式无明显影响,对位移值大小有影响。 相似文献
993.
A new 96-well disk solid phase extraction sample preparation technique which does not involve vacuum pumps integrated with liquid chromatographic tandem mass spectrometric (LC–MS/MS) was developed for high throughput determination of benzodiazepines (nordiazepam, diazepam, lorazepam and oxazepam). In addition, the method completely allows the re-use of the SPE disk membranes for subsequent analyses after re-conditioning. The method utilizes a robotic autosampler for parallel extractions in a 96-well plate format. Results have been presented for independent extractions from three matrices; phosphate buffer solution, urine, and plasma. Factors affecting data reproducibility, extraction kinetics, sample throughput, and reliability of the system were investigated and optimized. A total time required per sample was 0.94 min using 96-well format. Method reproducibility was ≤9% relative standard deviation for all three matrices. Limits of detection and quantitation recorded were respectively in the range 0.02–0.15 and 0.2–2.0 ng/mL with linearity ranging from 0.2 to 500 ng/mL for all matrices. 相似文献
994.
Does the thickness of the vertebral subchondral bone reflect the composition of the intervertebral disc? 总被引:1,自引:0,他引:1
S. Roberts I. W. McCall J. Menage M. J. Haddaway S. M. Eisenstein 《European spine journal》1997,6(6):385-389
Degeneration of the intervertebral disc, seen radiologically as loss of disc height, is often associated with apparent remodelling in the adjacent vertebral body. In contrast, maintenance or apparent increase in disc height is a common finding in osteoporosis, suggesting the properties of the intervertebral disc may be dependent on those of the vertebral body or vice versa. We have investigated this relationship by measuring the radiological thickness of the subchondral bone and comparing it to the chemical composition of the adjacent disc. Sagittal slabs were sampled from lumbar spines obtained at autopsy and X-rayed microfocally. The thickness of the subchondral bone was measured and correlated with the composition of the adjacent intervertebral disc. Eighty-three cadaveric endplates were studied from individuals aged 17–85 years. There was regional variation in thickness of the subchondral bone, being greater adjacent to the annulus than the nucleus, and the endplates cranial to the disc were thicker than those caudal. There was a positive correlation between the thickness of the subchondral bone and the proteoglycan content of the adjacent disc, particularly in the region of the nucleus. A weaker correlation was seen here between water content and thickness, whilst there was no significant correlation at the annulus or between the bone thickness and collagen content. The positive relationship between the radiographic thickness of vertebral subchondral bone and the proteoglycan content of the adjacent disc seen in human cadaveric material could be due to the bone responding to a greater hydrostatic pressure being exerted by discs with higher proteoglycan content than by those with less proteoglycan present. It is suggested that while this is true in normal specimens, the relationship becomes altered in disease states, possibly because of changes to the nutritional pathway of the disc, with resultant endplate-bone remodelling affecting the flow of solutes to and from the intervertebral disc. 相似文献
995.
在28例成人标本上经骼骨钻孔和非髂骨钻孔法做经皮穿刺L_5S_1椎间盘后1/3,分层解剖观测,探针依次经过皮肤,肌肉,纤维环至髓核;并观察针与临近最下腰动脉脊支。股神经,闭孔神经和腰骶干的解剖关系。实验表明:遵循操作规则,使用锥形扩张器,用上述两种方法穿刺L_5S_1椎间盘后1/3都是安全,可行的。 相似文献
996.
K. Puustjärvi T. Takala W. Wang M. Tammi H. J. Helminen V. Kovanen 《European spine journal》1993,2(3):126-131
Summary The effect of long-term exercise on the intervertebral disc collagen concentration (hydroxyproline), collagen-synthesizing enzymes (prolyl-4-hydroxylase, PH, and galactosyl-hydroxylysyl glucosyltransferase, GGT) and hydroxypyridinium crosslinks was studied in ten female beagle dogs. The dogs were run on a treadmill for 1 year starting at the age of 15 weeks. The daily running distance was gradually increased to 40 km, which distance the dogs ran for the final 15 weeks. Ten untrained dogs from the same breeding colony served as controls. The nucleus pulposus and anterior and posterior halves of the annulus fibrosus of C2–3, T10–12, L4–5 disc segments were analysed. Crosslinks were measured from the anterior annulus fibrosus of the T10–11 disc. Hydroxyproline and hydroxypyridinium concentrations remained similar in both groups. PH and GGT were significantly elevated by running in the posterior annulus fibrosus of the thoracic and lumbar discs and in the lumbar nucleus pulposus. In the thoracic nucleus pulposus GGT was reduced significantly. The results suggest activated collagen metabolism in the posterior annulus fibrosus of the thoracic and lumbar discs as a result of locally increased strains on the spine.The research was carried out at the Department of Anatomy, University of Kuopio 相似文献
997.
Percutaneous endoscopic lumbar discectomy (PELD) is a new technique for the decompression of the lumbar disc space and removal of nucleus pulposus via a posterolateral approach. The technique was introduced in Germany by the authors in April 1987. The method is indicated in patients with non-equestrated lumbar disc herniation with an intact lorsal longitudinal ligament. In local anesthesia, a working cannula (OD 5 mm) is placed at the dorsal lateral border of the disc. The disc space is opened with anulus trephines and the nucleus pulposus is removed with rigid and flexible forceps as well as with automated shaver systems under intermittent endoscopic control (discoscopy). The procedure is performed in local anesthesia. The results of the first thirty patients with a follow-up time between 6 months and 17 months could be graded as excellent in 13 cases, as good in 9 cases, as fair in 6 cases, and as bad in 2 cases. The relief of symptoms as judged by the patients was between 70–100 percent in the majority of the cases. Three patients had to be reoperated at the same level and site, because of either persistent or recurrent sciatica. The performance in local anesthesia, the atraumatic extraspinal approach, the reduced time of hospitalization and post-operative morbidity as well as the reduced time of work incapability are the main advantages of this new method. 相似文献
998.
本文报告了成人原发性椎间盘炎8例,其中男5例,女3例,年龄平均44.5岁。病变间隙:L1~21例,L2~34例,L3~L43例。入院前误诊为腰椎结核2例,椎体肿瘤3例。病因有三大学说即:细菌感染、无菌性炎症和自身免疫性反应,多数倾向于血源性细菌感染。讨论了临床特点、诊断与鉴别诊断及治疗问题。作者认为CRP和ESR较体温血象更敏感、更准确,可作为观察疗效的有效指标。本病应与腰椎结核、椎体肿瘤及退行性改变加以鉴别,MRI有助于本病的诊断。保守治疗以卧床、大剂量广谱抗菌素治疗为主。经皮椎间盘镜行病灶清除及活检术有助于诊断和治疗。对椎体破坏超过50%有神经受损症状、保守治疗无效者,手术病灶清除术同时可植骨融合,以增加脊柱稳定性。 相似文献
999.
Summary A positive result of re-operation in patients with recurrent symptoms after lumbar disc surgery is likely only if a new disc herniation is present. An improved ability to differentiate between recurrent disc herniation and scar tissue by contrast enhanced CT and MRI is suggested in earlier studies.In a prospective study 29 patients were selected for operation for suspected recurrent disc herniation. The inclusion of the patients was based on clinical symptoms and signs and myelography or non-enhanced CT. All patients were examined by CT and MRI both with and without intravenous contrast pre-operatively. The examinations were evaluated blind on a five point scale and statistical analysed by a regret function.Intravenous contrast improved the diagnostic power of both CT and MRI. MRI was superior to CT in both non-enhanced and enhanced examinations. MRI with intravenous contrast enhancement is proposed as the primary examination in patients with suspected recurrent disc herniation. 相似文献
1000.
Several unilateral external fixators were laboratory tested under applied axial, bending, and torsional loads. In certain cases the shear movement at the fracture site was substantial, up to 4 mm, and in all cases it was as significant as axial displacement. Also, under average full weight bearing, all the fixator/bone screw frameworks will allow too much axial movement at the fracture. This could inhibit healing and cause peak bone and screw stresses to approach yield. 相似文献