全文获取类型
收费全文 | 9917篇 |
免费 | 653篇 |
国内免费 | 27篇 |
专业分类
耳鼻咽喉 | 130篇 |
儿科学 | 231篇 |
妇产科学 | 205篇 |
基础医学 | 1209篇 |
口腔科学 | 268篇 |
临床医学 | 1194篇 |
内科学 | 1718篇 |
皮肤病学 | 72篇 |
神经病学 | 1031篇 |
特种医学 | 361篇 |
外科学 | 1776篇 |
综合类 | 86篇 |
一般理论 | 11篇 |
预防医学 | 1007篇 |
眼科学 | 148篇 |
药学 | 566篇 |
中国医学 | 7篇 |
肿瘤学 | 577篇 |
出版年
2023年 | 39篇 |
2022年 | 69篇 |
2021年 | 160篇 |
2020年 | 108篇 |
2019年 | 167篇 |
2018年 | 173篇 |
2017年 | 185篇 |
2016年 | 170篇 |
2015年 | 214篇 |
2014年 | 289篇 |
2013年 | 441篇 |
2012年 | 615篇 |
2011年 | 645篇 |
2010年 | 347篇 |
2009年 | 317篇 |
2008年 | 588篇 |
2007年 | 671篇 |
2006年 | 694篇 |
2005年 | 690篇 |
2004年 | 661篇 |
2003年 | 627篇 |
2002年 | 575篇 |
2001年 | 97篇 |
2000年 | 87篇 |
1999年 | 99篇 |
1998年 | 132篇 |
1997年 | 117篇 |
1996年 | 81篇 |
1995年 | 91篇 |
1994年 | 85篇 |
1993年 | 74篇 |
1992年 | 65篇 |
1991年 | 52篇 |
1990年 | 51篇 |
1989年 | 46篇 |
1988年 | 46篇 |
1987年 | 44篇 |
1986年 | 38篇 |
1985年 | 57篇 |
1984年 | 51篇 |
1983年 | 60篇 |
1982年 | 64篇 |
1981年 | 62篇 |
1980年 | 60篇 |
1979年 | 43篇 |
1978年 | 51篇 |
1977年 | 39篇 |
1976年 | 40篇 |
1973年 | 38篇 |
1971年 | 39篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
Primary ovarian mucinous carcinomas are uncommon and usually present as unilateral stage 1 neoplasms. The vast majority are of the so-called intestinal or enteric type and arise from a preexisting intestinal-type mucinous borderline neoplasm. The overall prognosis is good. However, a minor proportion recurs or metastasizes, and this is associated with a poor prognosis. The vast majority of primary ovarian intestinal-type mucinous carcinomas and borderline tumors exhibit a variable degree of positivity with enteric markers and are CA125 negative. The primary purpose of this study was to describe the unusual phenomenon of CA125 immunoreactivity in 8 of 10 metastatic mucinous carcinomas arising after a diagnosis of primary ovarian mucinous carcinoma (n=3) or mucinous borderline tumor of the intestinal type (n=7) in which the primary neoplasms were mostly negative. The reasons underlying this emergent CA125 positivity are not clear, but we speculate it may be because while intestinal type mucinous borderline neoplasms and mucinous carcinomas exhibiting so-called expansile invasion are usually CA125 negative, focal positivity may be seen in areas of infiltrative stromal invasion, which may preferentially metastasize. CA125 positivity in the metastatic neoplasm may result in the pathologist considering an alternative primary site; however, this should not be the case. In our study, we found a 4.2% risk of malignant progression after a diagnosis of primary ovarian mucinous borderline tumor of the intestinal type. In light of this, we favor retaining the term "mucinous borderline tumor," because of this small, but not insignificant, risk of malignant transformation, which in most cases is likely secondary to a focus of invasion being unsampled at the time of reporting the primary neoplasms. 相似文献
92.
Rebe KB Struthers H de Swardt G McIntyre JA 《Suid-Afrikaanse tydskrif vir geneeskunde》2011,101(10):708, 710
Men who have sex with men (MSM) are at high risk for HIV acquisition and transmission owing to the high risks associated with unprotected anal sex and barriers to accessing appropriate health services. Globally HIV prevention is failing among MSM, as evidenced by high seroconversion rates. Prevention interventions for MSM are more limited than for heterosexual individuals. Prevention programmes should embrace early their programming. High transmission risk groups such as MSM will benefit from such interventions. 相似文献
93.
Michael C. Park Marc A. Goldman John E. Donahue Glenn A. Tung Ritu Goel Prakash Sampath 《Skull base》2008,18(1):67-72
Tension pneumocephalus is an unusual, potentially life-threatening complication of frontal fossa tumors. We present an uncommon case of a frontoethmoidal osteoma causing a tension pneumocephalus and neurological deterioration prompting a combined endonasal ethmoidectomy and bifrontal craniotomy with craniofacial approach for resection. A 68-year-old man presented with a 1-week history of worsening headache, slowness of speech, and increasing confusion. Standard computed tomography scan revealed a marked tension pneumocephalus with ventricular air and 1-cm midline shift to the right. Further studies showed a calcified left ethmoid mass and a left anterior cranial-base defect. A team composed of neurosurgery and otolaryngology performed a combined endonasal ethmoidectomy and bifrontal craniotomy with craniofacial approach to resect a large frontoethmoid bony tumor. No abscess or mucocele was identified. The skull base defect was repaired with the aid of a transnasal endoscopy, a titanium mesh, and a pedunculated pericranial flap. Postoperatively, the pneumocephalus and the patient's symptoms completely resolved. Pathology was consistent with a benign osteoma. This is an uncommon case of a frontoethmoidal osteoma associated with tension pneumocephalus. Recognition of this entity and timely diagnosis and treatment, consisting of an endonasal ethmoidectomy and a bifrontal craniotomy with craniofacial approach, may prevent potential life-threatening complications. 相似文献
94.
Christian P. DiPaola MD Justin A. Jacobson MD Hani Awad PhD Bryan P. Conrad MSEng Glenn R. Rechtine II MD 《The spine journal》2008,8(5):717-722
BACKGROUND CONTEXT: Two common justifications for orienting cervical screws in an angled direction are to increase pullout strength and to allow use of longer screws. This concept is widely taught and has guided implant design. Fixed- versus variable-angle systems may offer strength advantages. Despite these teachings, there is a paucity of supporting biomechanical evidence. The purpose of our study is to test the influence of screw orientation and plate design on the maximum screw pullout force. PURPOSE: This study evaluates the effect of screw orientation and plate type (fixed- vs. variable-angle) on screw pullout strength. STUDY DESIGN: Anterior cervical plates of both a fixed- and variable-angle CSLP, were tested for peak pullout strength in a direct plate pullout model using polyurethane foam bone, which models osteoporotic bone. METHODS: Self-tapping, locking screws (4.0x14mm and 4.0x16mm) were used. Screws were oriented in the fixed-angle plate in the standard fashion. In the variable plate, screws were instrumented in three different orientations. Biomechanical testing was performed on an Instron DynaMight 8841 servohydraulic testing machine, measuring maximum pullout force under a displacement-controlled pullout rate of 1mm/min. Five samples were tested per group. RESULTS: When all screws were placed 90 degrees to the plate, there was a significantly increased peak pullout strength (412.8+/-22.2N) compared with when all screws were placed 12 degrees "up and in" (376.2+/-24.3N, p less than or equal to .03). When the 90 degrees construct was reproduced using 14-mm screws and compared with 16-mm screws oriented 12 degrees "all up and in," there was still significantly higher pullout strength with the all 90 degrees construct (434.2+/-28.7N vs. 376.2+/-24.3N, p less than or equal to .009). The fixed-angle plate had a significantly decreased peak pullout strength (288.2+/-15.7N) compared with the variable-angle plate (416.6+/-12.6N) (p less than .00001) when the screws were placed in the same orientation. Overall, the variable-angle plate, regardless of the orientation of screws, had a significantly greater pullout strength than the fixed-angle plate (p less than .001). CONCLUSIONS: In this system, a variable-angle plate has greater pullout strength than a fixed-angle plate, regardless of the orientation of screws. With the variable-angle plate, a construct of all screws 12 degrees "up and in" is the weakest configuration. We found that with the 90 degrees construct, both 16- and 14-mm screws performed significantly better than 16-mm convergent screws. These findings are remarkable because they contradict the current doctrine. This may be a function of plate-dependent factors and should not be applied universally to all plate systems. Further study of screw orientation in additional plating systems is warranted. 相似文献
95.
Yan TD King J Sjarif A Glenn D Steinke K Al-Kindy A Morris DL 《Annals of surgical oncology》2007,14(5):1718-1726
Background This study critically evaluated the local and overall treatment failure rates after percutaneous radiofrequency ablation (RFA)
of pulmonary metastases from colorectal carcinoma.
Methods Fifty-five nonsurgical candidates underwent RFA of colorectal pulmonary metastases. The primary end points of this study were
local progression-free survival (PFS) and overall PFS. Univariate and multivariate analyses were performed to identify significant
prognostic parameters for local and overall PFS.
Results The local recurrence rate was 38%. For local PFS, univariate analysis demonstrated that the largest size of lung metastasis,
the location of lung metastases, the post-RFA carcinoembryonic antigen level at 1 month, and the post-RFA carcinoembryonic
antigen level at 3 months were significant prognostic indicators. In multivariate analysis, a largest size of lung metastasis
of >3 cm and a post-RFA carcinoembryonic antigen level of >5 ng/mL at 1 month were independently associated with a reduced
local PFS. The overall recurrence rate was 66%. For overall PFS, univariate analysis demonstrated that sex and the largest
size of lung metastasis were significant prognostic indicators. In multivariate analysis, a largest size of lung metastasis
of >3 cm was independently associated with a reduced overall PFS.
Conclusions RFA of colorectal pulmonary metastases may have a useful role in local disease control for nonsurgical candidates, but its
efficacy in patients with a lung metastasis of >3 cm is limited. 相似文献
96.
Magit DP Hilibrand AS Kirk J Rechtine G Albert TJ Vaccaro AR Simpson AK Grauer JN 《Journal of spinal disorders & techniques》2007,20(4):282-289
STUDY DESIGN: Questionnaire study presented to practicing spine surgeons. OBJECTIVE: To evaluate surgeon preference and availability of selected electrophysiologic neuromonitoring for different spine surgeries. SUMMARY OF BACKGROUND DATA: Maximizing the safety of spinal procedures and limiting potential iatrogenic neurologic injury has made intraoperative neuromonitoring an attractive option. METHODS: We distributed a questionnaire to 180 orthopedic spine surgeons and neurosurgeons at a clinically oriented spine meeting asking surgeon preference and availability of various types of intraoperative neuromonitoring modalities for different types of surgical procedures. Demographic data were also gathered. RESULTS: Somatosensory evoked potentials (SSEPs) were the most available neuromonitoring modality, followed by electromyographies and motor-evoked potentials. In both anterior and posterior cervical surgery, SSEPs were the most preferred modality. MEPs were frequently preferred in myelopathic cervical cases. Almost 70% preferred some neuromonitoring for anterior thoracic/thoracolumbar cases and 55% for posterior thoracic/thoracolumbar cases. Surgeon satisfaction was related to the number of available neuromonitoring modalities. No significant differences were found between orthopedist and neurosurgeon preferences. Fellowship-trained surgeons were more likely to use neuromonitoring for specific indications. CONCLUSIONS: SSEPs remains the most widely available and preferred type of neuromonitoring for spine surgeons. The type of case and neurologic status of patient (eg, presence of myelopathy) affects these choices. Surgeons were more satisfied with greater neuromonitoring availability, and were more likely to use neuromonitoring if they had a fellowship background. 相似文献
97.
Surgical revascularization versus endovascular therapy for chronic mesenteric ischemia: a comparative experience 总被引:2,自引:0,他引:2
Atkins MD Kwolek CJ LaMuraglia GM Brewster DC Chung TK Cambria RP 《Journal of vascular surgery》2007,45(6):1162-1171
INTRODUCTION: Endovascular therapy (percutaneous transluminal angioplasty [PTA] with stenting) has been increasingly applied in patients with chronic mesenteric ischemia (CMI) to avoid morbidities associated with open repair (OR). The purpose of this study was to compare outcomes of PTA/Stent vs OR in patients with symptomatic CMI. METHODS: During the interval of January 1991 to December 2005, 80 consecutive patients presenting with symptomatic CMI underwent elective revascularization. Patients with acute mesenteric ischemia or those with mesenteric revascularization performed as part of complex aneurysm repair were excluded. PTA/Stent (with stenting in 87%) was the initial procedure in 31 patients (42 vessels). OR was performed in 49 patients (88 vessels) and consisted of bypass grafting in 31 (63%), transaortic endarterectomy in 7 (14%), patch angioplasty in 4 (8%), or combined in 7 (15%). Mean follow-up was 15 months in the PTA/Stent group and 42 months in the OR cohort. Study end points included perioperative morbidity, mortality, late survival (Kaplan-Meier), and symptomatic and radiographic recurrence. RESULTS: Baseline comorbidities, with the exception of heart disease (P=.025) and serum albumin<3.5 g/dL (P=.025), were similar between PTA/Stent and OR patients. The PTA/Stent group had fewer vessels revascularized (1.5 vs 1.8 vessels, P=.001). Hospital length of stay was less for the PTA/Stent group (5.6 vs 16.7 days, P=.001). No difference was noted in in-hospital major morbidity (4/31 vs 2/49, P=.23) or mortality (1/31 vs 1/49, P=.74). Actuarial survival at 2 years was similar between the groups (88% PTA/Stent vs 74% OR, P=.28). There was no difference in the incidence of symptomatic (7/31 [23%] vs 11/49 [22%], P=.98) or radiographic recurrence (10/31 [32%] vs 18/49 [37%], P=.40) between the two groups. Radiographic primary patency (58% vs 90%, P=.001) and primary assisted patency (65% vs 96%, P<.001) at 1 year were lower in the PTA/Stent group compared with OR. Five (16%) of 31 PTA/Stent patients compared with 11 (22%) of 49 OR patients required a second intervention on at least one index vessel at any time (P=.49). CONCLUSIONS: Symptomatic recurrence requiring reintervention is common (overall 16/80 [20%]) after open and endovascular treatment for CMI. PTA/Stent was associated with decreased primary patency, primary assisted patency, and the need for earlier reintervention. In-hospital mortality or major morbidity were similar in patients undergoing PTA/Stent and OR. These findings suggest that OR and PTA/Stent should be applied selectively in CMI patients in accordance with individual patient anatomic and comorbidity considerations. 相似文献
98.
Glenn M. Hall Skandan ShanmuganTamar Nobel B.S. Raj PaspulatiConor P. Delaney M.D. Ph.D. Harry L. ReynoldsSharon L. Stein M.D. Bradley J. Champagne M.D. 《American journal of surgery》2014
Background
The surgical indications for symptomatic rectocele are undefined, and surgery has high recurrence rates. We implemented magnetic resonance imaging defecography (MRID) to determine if utilizing strict inclusion criteria for rectocele repair improves outcomes.Methods
Patients with obstructive defecation syndrome (ODS) who underwent dynamic MRID were evaluated. Indications for surgical repair were defecation requiring manual assistance and the following MRID results: anterior defect >2 cm, incomplete evacuation, and the absence of perineal descent. Primary outcomes were the change in quality of life (QOL) scores and recurrence.Results
From 2006 to 2013, 143 patients who presented with ODS underwent MRID. Seventeen patients met the criteria for repair. Recurrence was low (5.8%) with a median follow-up of 23 months, QOL scores improved from 57.3 to 76.5 (P = .041).Conclusions
A minority of patients (12%) with ODS met the above criteria for rectocele repair. Patients who underwent repair had a significant improvement in QOL and low recurrence rate. 相似文献99.
Percutaneous Imaging–Guided Radiofrequency Ablation in Patients With Colorectal Pulmonary Metastases: 1-Year Follow-Up 总被引:3,自引:2,他引:3
Steinke K Glenn D King J Clark W Zhao J Clingan P Morris DL 《Annals of surgical oncology》2004,11(2):207-212
Background: We assessed the safety and evidence of efficacy of radiofrequency ablation (RFA) for colorectal lung metastases with follow-up to 1 year.Methods: Twenty-three patients had percutaneous RFA for 52 colorectal pulmonary metastases under fluoro-computed tomography (CT). Patients received intravenous conscious sedation and local analgesia with routine hospitalization and monitoring for 24 hours after RFA. Patients had CT scanning at 1 month and then every 3 months, with serum carcinoembryonic antigen assessment monthly and every 3 months.Results: All ablations were technically successful. Tumor diameter ranged from .3 to 4.2 cm. Pneumothorax occurred in 43% (10 of 23) of patients. Six patients required intercostal chest drain placement. Six patients had a second RFA, four for new lesions and two for re-treatment of a previously treated lesion. The median admission was 2.0 days (range, 1–9 days). The median follow-up was 428 days (range, 173–829 days); data are reported to 1 year in this article. Five patients died at 5, 6, 8, 8, and 12 months after RFA from extrapulmonary (n = 1) or widespread (n = 4) disease. One patient developed a malignant pleural effusion at 6 months after RFA. Cavitation was seen in nine treated lesions (17%); all resolved with scar tissue contraction by 12 months. Eighteen patients with CT scan follow-up at 1 year have 40 lesions classified as disappeared (n = 17), decreased (n = 5), stable/same size (n = 4), or increased (n = 14).Conclusions: Percutaneous imaging–guided RFA of multiple colorectal pulmonary metastases is a minimally invasive treatment option with modest morbidity. A significant proportion of patients show good evidence of successful local control at 1 year. 相似文献
100.
BACKGROUND CONTEXT: Currently, artificial spinal discs require transection or partial removal of the annulus fibrosis in order to excise the nucleus and implant a prosthetic nucleus or implant a total disc device, respectively. Preservation of the annulus for prosthetic disc replacement maintains the function of the annulus and may improve annulus load sharing with the prosthesis. PURPOSE: To quantify the biomechanical characteristics of an annular sparing intervertebral prosthetic disc (IPD) in a lumbar calf spine model. The aim of the study was to determine whether altering the stiffness of the elastic component of this unique prosthesis would correspond to changes of the overall reconstructed disc. STUDY DESIGN/SETTING: A biomechanical study was conducted in vitro using cadaveric calf spines such that each specimen served as its own control. Investigations were performed at the Minneapolis Medical Research Foundation, Orthopaedic Biomechanics Laboratory. METHODS: Six L45 or L56 motion segments (from which the posterior elements had been removed) were studied in axial compression, sagittal and lateral bending and torsion. These load states were applied to the intact, denucleated and prosthetically reconstructed disc using four IPDs of differing stiffness. RESULTS: Load-displacement testing demonstrated that stiffer IPDs resulted in a decreased range of motion and neutral zone, and greater stiffness of the reconstructed disc. Disc reconstruction with the stiffest IPD approximated the behavior of the intact disc. CONCLUSIONS: The overall biomechanical characteristics of a reconstructed disc are related to the stiffness of a nucleus prosthesis. The similarities in the mechanical behavior of reconstructed and intact discs suggest that additional feasibility studies for the annulus-sparing IPD are warranted. 相似文献