首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   11583篇
  免费   514篇
  国内免费   37篇
耳鼻咽喉   302篇
儿科学   1024篇
妇产科学   313篇
基础医学   1184篇
口腔科学   252篇
临床医学   729篇
内科学   1955篇
皮肤病学   224篇
神经病学   769篇
特种医学   283篇
外科学   1907篇
综合类   223篇
一般理论   2篇
预防医学   715篇
眼科学   413篇
药学   923篇
中国医学   66篇
肿瘤学   850篇
  2023年   58篇
  2022年   177篇
  2021年   336篇
  2020年   216篇
  2019年   250篇
  2018年   260篇
  2017年   215篇
  2016年   300篇
  2015年   311篇
  2014年   485篇
  2013年   575篇
  2012年   801篇
  2011年   863篇
  2010年   581篇
  2009年   392篇
  2008年   682篇
  2007年   658篇
  2006年   674篇
  2005年   612篇
  2004年   503篇
  2003年   461篇
  2002年   416篇
  2001年   134篇
  2000年   101篇
  1999年   112篇
  1998年   103篇
  1997年   66篇
  1996年   66篇
  1995年   68篇
  1994年   46篇
  1993年   49篇
  1992年   70篇
  1991年   79篇
  1990年   65篇
  1989年   90篇
  1988年   67篇
  1987年   74篇
  1986年   74篇
  1985年   67篇
  1984年   57篇
  1982年   47篇
  1981年   53篇
  1980年   49篇
  1979年   65篇
  1978年   43篇
  1976年   45篇
  1975年   51篇
  1974年   61篇
  1971年   46篇
  1970年   50篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
101.

Introduction

We assessed the validity of “perfusion-metabolism coupling” hypothesis in recurrent glioma with 13N-ammonia (13N-NH3) PET/CT and 18F-fluorodeoxyglucose (18F-FDG) PET/CT.

Methods

Fifty-six consecutive patients (age, 38.8?±?12.1 years; 62.5 % males) with histologically proven and previously treated glioma presenting with clinical suspicion of recurrence were prospectively enrolled and evaluated with 13N-NH3 PET/CT and 18F-FDG PET/CT. PET/CT images were evaluated both qualitatively and semiquantitatively. Tumor to white matter uptake ratio (T/W) and tumor to gray matter uptake ratio (T/G) were calculated and analyzed for both the modalities. A combination of clinico-radiological follow-up, repeated imaging, and biopsy (when available) were considered as the reference standard.

Results

Based on the reference standard, 27/56 patients had recurrence. 13N-NH3 PET/CT and 18F-FDG PET/CT were concordant in 55/56 patients. Overall sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of 13N-NH3PET/CT were 77.8, 86.2, 84.0, 80.7, and 82.1 %, respectively, and for 18F-FDG PET/CT were 77.8, 89.7, 87.5, 81.2, and 83.9 %, respectively. There was excellent agreement between results of 13N-NH3 PET/CT and 18F-FDG PET/CT (??=?0.964; P?13N-NH3 PET/CT and 18F-FDG PET/CT were not significantly different between high-grade and low-grade glioma (P?=?1.000). A strong positive correlation was noted between the uptake ratios derived on the two modalities (ρ?=?0.866, P?ρ?=?0.918, P?Conclusion A combination of 13N-NH3 PET/CT and 18F-FDG PET/CT demonstrates that perfusion and metabolism are coupled in recurrent gliomas. These tracers target two different but interrelated aspects of the same pathologic process and can be used as surrogates for each other.  相似文献   
102.
BACKGROUND AND OBJECTIVES: Temporary dermal clearing, i.e., reduction in the attenuation coefficient of the dermis and epidermis, may lead to improved laser tattoo removal by providing increased efficiency of laser delivery to embedded ink particles and enabling the use of shorter wavelength visible lasers more effective on certain inks. STUDY DESIGNS/MATERIALS AND METHODS: In a hairless guinea pig model of human tattoo, we tested both intradermal and transdermal application of glycerol, using visual inspection, spectral analysis, and optical coherence tomography techniques to assess effectiveness. In controlled experiments, we compared the outcomes of single laser treatment sessions for both cleared and uncleared tattoo sites using Q-switched 755 and 532 nm lasers on three different inks. RESULTS: Intradermal injection of clearing agents induced dermal clearing but resulted in necrosis and scar. Transdermal application of clearing agents resulted in moderate reversible clearing, which was localized to the superficial layers of the skin and did not result in complications. Statistically significant differences in laser treatment outcome were observed relative to a number of treatment parameters including the treatment of certain tattoos by short wavelength lasers. CONCLUSIONS: Temporary clearing of superficial skin layers may be performed in an apparently safe and reliable manner. Clearing should lead to increased penetration of laser light to tattoos and should, therefore, increase treatment efficiency. Further study is needed to determine the degree to which this change is of clinical value.  相似文献   
103.
Alcohol and tobacco use commonly co-occur, with at least 90% of those with an alcohol problem also using tobacco. Thus, 3 years ago when we discovered higher rate of late deaths due to lung and oropharyngeal cancer in patients who had received a transplant for alcoholic liver disease (ALD), we hypothesized that these patients were continuing to expose themselves to tobacco after liver transplantation (post-LTX) and that this behavior was increasing their risk for cancer. We subsequently began a prospective investigation of post-LTX tobacco use in patients having undergone LTX for ALD (n = 172). For 33 recipients we had data starting from our first assessment at 3 months post-LTX and for this subgroup we report on the details of the timing of tobacco use resumption and the redevelopment of nicotine addiction. We found that on average more than 40% are smoking across all time periods. ALD recipients resume smoking early post-LTX, increase their consumption over time, and quickly become tobacco dependent. These data highlight an underrecognized serious health risk for these patients and demonstrate our need for more stringent clinical monitoring and intervention for tobacco use in the pre- and post-LTX periods.  相似文献   
104.
We evaluated the optimal preemptive dose of gabapentin for postoperative pain relief after single-level lumbar diskectomy and its effect on fentanyl consumption during the initial 24 hours in a randomized, double-blinded, placebo-controlled study in 100 patients with American Society of Anesthesiologists physical status I and II. Patients were divided into five groups to receive placebo or gabapentin 300, 600, 900, or 1200 mg 2 hours before surgery. After surgery, patients were transferred to the postanesthesia care unit (PACU). A blinded anesthesiologist recorded the pain scores at time points of 6, 12, 18, and 24 hours in the PACU on a Visual Analog Scale (VAS; 0-10 cm) at rest. Patients received patient-controlled analgesia (fentanyl 1.0 mug/kg on each demand with lockout interval of 10 minutes); total fentanyl consumption during initial 24 hours was recorded. Data were entered into the statistical software package SPSS 9.0 for analysis (one-way analysis of variance and Student-Newman-Keuls test). Patients who received gabapentin 300 mg had significantly lower VAS score at all time points. They consumed less fentanyl (patients who received placebo processed 1217.5 +/- 182.0 versus 987.5 +/- 129.6 mug; P < 0.05). Patients who received gabapentin 600, 900, and 1200 mg had lower VAS scores at all time points than patients who received gabapentin 300 mg (P < 0.05). Increasing the dose of gabapentin from 600 to 1200 mg did not decrease the VAS score, nor did the increasing dose of gabapentin significantly decrease fentanyl consumption (702.5, 635, and 626.5 microg). Thus, gabapentin 600 mg is the optimal dose for postoperative pain relief following lumbar diskectomy.  相似文献   
105.
Hammer GB  Ramamoorthy C  Cao H  Williams GD  Boltz MG  Kamra K  Drover DR 《Anesthesia and analgesia》2005,100(5):1283-8, table of contents
The aim of this prospective, randomized, controlled clinical trial was to define the opioid analgesic requirement after a remifentanil (REMI)-based anesthetic with spinal anesthetic blockade (SAB+REMI) or without (REMI) spinal blockade for open-heart surgery in children. We enrolled 45 patients who were candidates for tracheal extubation in the operating room after cardiac surgery. Exclusion criteria included age <3 mo and >6 yr, pulmonary hypertension, congestive heart failure, contraindication to SAB, and failure to obtain informed consent. All patients had an inhaled induction with sevoflurane and maintenance of anesthesia with REMI and isoflurane (0.3% end-tidal). In addition, patients assigned to the SAB+REMI group received SAB with tetracaine (0.5-2.0 mg/kg) and morphine (7 mug/kg). After tracheal extubation in the operating room, patients received fentanyl 0.3 mug/kg IV every 10 min by patient-controlled analgesia for pain score = 4. Pain scores and fentanyl doses were recorded every hour for 24 h or until the patient was ready for discharge from the intensive care unit. Patients in the SAB+REMI group had significantly lower pain scores (P = 0.046 for the first 8 h; P =0.05 for 24 h) and received less IV fentanyl (P = 0.003 for the first 8 h; P = 0.004 for 24 h) than those in the REMI group. There were no intergroup differences in adverse effects, including hypotension, bradycardia, highest PaCO(2), lowest pH, episodes of oxygen desaturation, pruritus, and vomiting.  相似文献   
106.

Objective

Currently, there is no effective paradigm to identify patients who are at risk for renal dysfunction following cardiac surgery. The specific mechanisms of renal injury during surgery are incompletely understood. The aim of the study was to evaluate whether postoperative renal dysfunction can be predicted from intraoperative glomerular filtration rate (GFR).

Design

This is a prospective study.

Setting

The study was conducted in a tertiary care multi-specialty hospital.

Participants and interventions

GFR was measured in 24 patients (mean age 56.6 ± 11.09 years, 20 male) undergoing elective off-pump coronary artery bypass grafting during preoperative period, intraoperative period, 24 h after surgery (ICU GFR), and on the fifth postoperative day (final GFR ).

Measurements and main results

Patients were divided into two groups depending upon changes in intraoperative GFR. Group 1 (n = 10): who had a rise in intraoperative GFR in comparison with preoperative baseline measurement. All these 10 (41.7 %) patients with a rise in intraoperative GFR had an uneventful hospital course and achieved an improvement in final GFR. Group 2 (n = 14): 14 (58.3 %) patients had a fall in intraoperative GFR (mean 36.4 %) in comparison with preoperative baseline value. Of these 14 patients, 1 patient required dialysis support and 3 patients required ionotropic support. Among these 14 patients in group two, 7 had deterioration in final GFR (mean 28.7 %), when compared to preoperative baseline value.

Conclusion

Postoperative renal dysfunction can be predicted from intraoperative GFR. Patients who have a rise in intraoperative GFR do not develop postoperative renal dysfunction, and only patients with intraoperative fall in GFR are at risk of postoperative renal dysfunction.
  相似文献   
107.
Objective  This is the first report of the simultaneous combined use of trans-sphenoidal and trans-ventricular-endoscopic route for decompression of a giant pituitary adenoma. Method  A 38 year old man presented to us with symptoms of raised intracranial pressure along with visual and hypothalamic disturbances. The CT scan revealed destruction of the sella by a large (5 × 3.5 × 2.5 cm) well defined enhancing mass in the sella and suprasellar region extending laterally up to the cavernous sinuses and both carotid arteries and superiorly into the lumen of the 3rd ventricle producing obstructive hydrocephalus. On T2WI of the non-contrast MRI scan the mass was iso-intense to grey matter suggesting the possibility of a firm nature of the adenoma. The tumour was first approached by the standard trans-sphenoidal route and as predicted from the pre-operative MRI, the tumour was found to be firm and not amenable to suction. After decompression of the intra-sellar part of the tumour, the intracranial pressure was raised in an attempt to make the remainder of the tumour descend into the sella but without success. The suprasellar part of the tumour was then simultaneously addressed via a trans-ventricular-endoscopic route but the firm tumour did not yield to endoscopic instruments viz. biopsy forceps, angiographic catheter and electrosurgical probes. It was then gently pushed down towards the sella and decompressed piecemeal by using trans-sphenoidal instruments. The sellar cavity was reconstructed using fat, fascia lata graft and a piece of septal bone. Results  Post-operatively, the patient showed a remarkable improvement of his symptoms of raised intracranial pressure, hypothalamic dysfunction and visual disturbances. Follow-up imaging at 2 months and 1 year, did not show any residual or recurrent tumour. Conclusions  This novel technique of the combined trans-sphenoidal and simultaneous trans-ventricular-endoscopic approach is a viable option for patients with giant fibrous pituitary adenoma when the tumour is not yielding to the trans-sphenoidal route alone.  相似文献   
108.
We analysed the results of 24 cases of aggressive benign and malignant tumours of the distal radius treated by resection and prosthetic replacement between 1995 and 2006. Patient ages ranged from 18 to 74 years, averaging 33 years; 18 were males. Recurrent giant cell tumour was the most common tumour. The prosthesis used was a bipolar hinge custom mega prosthesis manufactured locally. Average follow-up was 78 months. The average Musculoskeletal Tumor Society (MSTS) functional score achieved was 75%. The ten-year prosthesis survival was rate 87.5%. Infection was the most common complication.
Resume  Prothèses sur mesure dans les tumeurs du radius distal. Indications de remplacement. Nous avons analysé les résultats de 24 cas de tumeurs malignes et bégnines agressives de l’extrémité distale du radius traitées par résection et prothèses entre 1995 et 2006. Les patients étaient agées de 18 à 74 ans avec un age moyen de 33 ans dont- 18 étaient des hommes. La cause la plus fréquente a été la récidive de tumeur à cellules géantes. La prothèse utilisée était une prothèse bipolaire à charnière sur mesure fabriquée localement. Le suivi moyen a été de 78 mois. Le score moyen MSTS après traitement était de 75%, la courbe de survie à 10 ans de 87,5%. La complication la plus fréquente a été l’infection.
  相似文献   
109.
Introduction  Primary sclerosing cholangitits (PSC) is a progressive fibrosing cholangiopathy eventually leading to end-stage liver disease (ESLD). While literature for deceased donor liver transplantation (DDLT) for PSC abounds, only a few reports describe live donor liver transplant (LDLT) in the setting of PSC. We present a single-center experience on survival outcomes and disease recurrence for LDLT and DDLT for ESLD secondary to PSC. Aim  The aim of this study was to analyze survival outcomes and disease recurrence for LDLT and DDLT for ESLD secondary to PSC. Patients and Methods  A retrospective review of 58 primary liver transplants for PSC-associated ESLD, performed between May 1995 and January 2007, was done. Patients were divided into two groups based on donor status. Group 1 (n = 14) patients received grafts from living donors, while group 2 (n = 44) patients received grafts from deceased donors. An analysis of survival outcomes and disease recurrence was performed. Recurrence was confirmed based on radiological and histological criteria. Results  Recurrence of PSC was observed in four patients in LDLT group and seven in DDLT group. Retransplantation was required in one patient in LDLT group and nine patients in DDLT group. One patient (7%) among LDLT and six patients (14%) among DDLT died. The difference in patient and graft survival was not statistically significant between the two groups (patient survival, p = 0.60; graft survival, p = 0.24). Conclusion  This study demonstrates equivalent survival outcomes between LDLT and DDLT for PSC; however, the rate of recurrence may be higher in patients undergoing LDLT.  相似文献   
110.
Objectives  We prospectively evaluated the safety, feasibility, and efficiency of robotic radical nephrectomy (RRN) for localized renal tumors (T1-2N0M0) and compared this with laparoscopic radical nephrectomy (LRN). Materials and methods  Between October 2006 to August 2007, a prospective data analysis of 15 cases of renal cell carcinoma (RCC) stage T1-2N0M0, undergoing RRN was done. These patients were compared with a contemporary cohort of 15 patients of RCC with clinical stage T1-2N0M0, undergoing LRN. To keep comparison robust, all cases were performed by a single surgeon. Demographic, intra-operative, post-operative outcomes, pathological characteristics and follow-up data of the two groups were recorded and analyzed statistically. Results  Patients in group A (RRN) experienced significantly (P = 0.001) long operating time than group B (LRN). However, mean estimated blood loss, intra-operative and post-operative complications, blood transfusion rate, analgesic requirement, hospital stay and convalescence were comparable in two groups (P < 0.05). There was one conversion to open surgery in group A, and none in group B. The mean follow-up was comparable in two groups (8.3 and 9.1 months, respectively, in group A and B, P = 0.09). There were no local, port-site or distal recurrences in either group. Conclusions  Robotic radical nephrectomy is a safe, feasible and effective for performing radical nephrectomy for localized RCC. Both groups (RRN and LRN) had comparable intra-operative, peri-operative, post-operative and oncological outcomes except for longer operating time with increased cost for RRN. In this comparative study, there were no outstanding benefits of RRN observed over LRN for localized RCC.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号