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   1204篇
  免费   134篇
  国内免费   2篇
耳鼻咽喉   6篇
儿科学   17篇
妇产科学   29篇
基础医学   168篇
口腔科学   9篇
临床医学   172篇
内科学   283篇
皮肤病学   3篇
神经病学   75篇
特种医学   54篇
外科学   187篇
综合类   26篇
一般理论   2篇
预防医学   139篇
眼科学   17篇
药学   75篇
肿瘤学   78篇
  2021年   16篇
  2020年   18篇
  2018年   11篇
  2017年   14篇
  2016年   23篇
  2015年   13篇
  2014年   20篇
  2013年   28篇
  2012年   48篇
  2011年   42篇
  2010年   33篇
  2009年   26篇
  2008年   55篇
  2007年   62篇
  2006年   57篇
  2005年   53篇
  2004年   56篇
  2003年   60篇
  2002年   51篇
  2001年   39篇
  2000年   29篇
  1999年   25篇
  1998年   21篇
  1997年   15篇
  1996年   17篇
  1995年   18篇
  1994年   24篇
  1993年   12篇
  1992年   30篇
  1991年   32篇
  1990年   25篇
  1989年   19篇
  1988年   16篇
  1987年   16篇
  1986年   16篇
  1985年   16篇
  1984年   15篇
  1982年   11篇
  1981年   15篇
  1979年   13篇
  1978年   13篇
  1977年   13篇
  1976年   14篇
  1975年   10篇
  1973年   12篇
  1972年   13篇
  1971年   11篇
  1970年   13篇
  1945年   11篇
  1944年   10篇
排序方式: 共有1340条查询结果,搜索用时 31 毫秒
1.

Background

Many patients undergoing below knee amputations (BKA) return for subsequent unplanned operations, hospital readmission, or postoperative complications. This unplanned medical management negatively impacts both patient outcomes and our healthcare system. This study primarily investigates the risk factors for unplanned reoperation following BKA.

Methods

Below knee amputations from the American College of Surgeons (ACS) National Surgical Quality Improvement Program (NSQIP) database from the years 2012–2014 were identified by CPT code 27880 for amputation through the tibia and fibula. Our query identified 4631 BKA cases, including 30 day complications. Multivariate logistic regression modeling was performed on several patient demographic and disease factors to assess for independent predictors of unplanned reoperation. Secondary outcomes of unplanned and related readmissions (related to the procedure), major complications, minor complications, and mortality were also included in the analysis.

Results

Of 4631 BKAs identified, 9.63% (446/4631) underwent unplanned reoperations and 8.75% (405/4631) had unplanned and related readmissions. Major complications were experienced by 12.8% (593/4631) and minor complications by 8.7% (401/4631). Thirty day mortality rate was 5.14% (238/4631). The most common procedures for unplanned operations were thigh amputations (128/446, 28.7%), debridement/secondary closure (114/446, 25.6%), and revision leg amputations (46/446, 10.32%). Factors associated with an increased risk of unplanned reoperation included patients transferred from another facility (Adjusted Odds Ratio [AOR]?=?1.28; p?=?.04), recent smokers (AOR?=?1.34; p?=?.02), bleeding disorder (AOR?=?1.30; p?=?.02), and preoperative ventilator use (AOR?=?2.38; p?=?.01).

Conclusion

Patients that were ongoing/recent smokers, had diagnosed bleeding disorders, required preoperative ventilator use, or were transferred in from another facility were associated with the highest risks of reoperation following BKA. This patient population experiences high rates of reoperation, readmission, complication, and mortality.  相似文献   
2.
Motion is a major confound in diffusion‐weighted imaging (DWI) in the body, and it is a common cause of image artefacts. The effects are particularly severe in cardiac applications, due to the nonrigid cyclical deformation of the myocardium. Spin echo‐based DWI commonly employs gradient moment‐nulling techniques to desensitise the acquisition to velocity and acceleration, ie, nulling gradient moments up to the 2nd order (M2‐nulled). However, current M2‐nulled DWI scans are limited to encode diffusion along a single direction at a time. We propose a method for designing b‐tensors of arbitrary shapes, including planar, spherical, prolate and oblate tensors, while nulling gradient moments up to the 2nd order and beyond. The design strategy comprises initialising the diffusion encoding gradients in two encoding blocks about the refocusing pulse, followed by appropriate scaling and rotation, which further enables nulling undesired effects of concomitant gradients. Proof‐of‐concept assessment of in vivo mean diffusivity (MD) was performed using linear and spherical tensor encoding (LTE and STE, respectively) in the hearts of five healthy volunteers. The results of the M2‐nulled STE showed that (a) the sequence was robust to cardiac motion, and (b) MD was higher than that acquired using standard M2‐nulled LTE, where diffusion‐weighting was applied in three orthogonal directions, which may be attributed to the presence of restricted diffusion and microscopic diffusion anisotropy. Provided adequate signal‐to‐noise ratio, STE could significantly shorten estimation of MD compared with the conventional LTE approach. Importantly, our theoretical analysis and the proposed gradient waveform design may be useful in microstructure imaging beyond diffusion tensor imaging where the effects of motion must be suppressed.  相似文献   
3.
ABSTRACT

Screening rates for trauma are low in health care settings. We examined the association between health care providers’ (HCPs) experience of physical or sexual trauma and their screening of female patients for trauma. HCPs at an urban academic medical institution were surveyed from September through November 2016. The Brief Trauma (BTQ) and Sexual and Physical Abuse History Questionnaires (SPAHQ) assessed their own experiences of trauma. The Screening Practices Questionnaire (SPQ) assessed HCPs trauma screening. Multiple regression analyses were performed. Among 212 respondents aged 22–67 years, most were female (78.3%) and white (76.1%). Nurses (41.0%) were the largest occupational group. Overall, 85.8% reported having experienced trauma. No significant difference was observed in median SPQ scores between HCPs who had experienced trauma (3.88 [Interquartile Range (IQR) 3.44–4.31]) and those who had not (4.00 [IQR 3.47–4.33], p = .645). In an adjusted model, screening policy awareness and having an obstetrics & gynecology or psychiatry specialty were associated with higher SPQ scores (p < .001). The prevalence of trauma experience in this sample was high, but not associated with screening. Screening policy awareness and practice specialty were associated with screening. HCP factors associated with greater trauma screening should be explored.  相似文献   
4.
5.
Little attention has been directed toward inappropriate social and sexual approaches by patients with dementia diagnoses and organic disorders of the brain. A female student who approached patients who had dementia and organic brain disorders was frequently approached and touched in a sexual manner that was distressing to her and led her to believe that she was behaving in a manner that elicited these responses. It is recommended that students and volunteers be prepared for experience in settings with patients with these diagnoses through individual or group discussion, training and role playing as a way of enhancing their experiences and avoiding unnecessary feelings of guilt and embarrassment.  相似文献   
6.
A new approach to parathyroidectomy.   总被引:9,自引:1,他引:8       下载免费PDF全文
OBJECTIVE: To decrease the operative time for parathyroidectomy in patients with hypercalcemic (primary) hyperparathyroid disease, a combination of preoperative localization of a parathyroid tumor with an effective nuclear scan (scintigram) and intraoperative monitoring of parathyroid hormone (quick parathyroid hormone measurement) to ensure excision of all hyperfunctioning tissue was studied. SUMMARY BACKGROUND DATA: For many years, persistent hypercalcemia after parathyroidectomy (3% to 10%) has been constant and is usually due to the surgeon's failure to remove all hyperfunctioning glands. A marked decrease in parathormone level after excision of a single large gland predicts operative success and a return to normal calcium levels. Conversely, persistent high levels of parathyroid hormone indicate excess secretion by another gland(s) and the need for further exploration. Recently Tc-99m-sestamibi (MIBI) scintigraphy was shown to be more effective in localizing parathyroid tumors than previous methods. A combination of both techniques could be useful to the surgeon if they improve the operative success rate and are cost-effective. METHODS: Parathyroidectomy was performed on 18 patients with primary hyperparathyroid disease, with tumors localized by MIBI scintigrams. When excision of the identified parathyroid gland was accomplished, the operation was terminated and quick parathyroid hormone was measured to confirm that all hyperfunctioning tissue was removed. RESULTS: Sixteen patients with positive results of scintigram had successful parathyroidectomies confirmed by quick parathyroid hormone measurement with a cervical approach. Two patients with mediastinal tumors localized by MIBI scintigraphy could not be resected using this approach. One false-positive/false-negative scintigram was obtained. Compared with patients having parathyroidectomy without localization and hormone monitoring, the average operative time was shortened from 90 to 36 minutes. CONCLUSIONS: Localization and successful excision of parathyroid tumors with confirmation that no other hyperfunctioning glands were present by quick parathyroid hormone monitoring can predict a return to normal calcium levels and a decrease in operative time in parathyroidectomy.  相似文献   
7.
A method for monitoring formation of latex particle pairs by chemiluminescence is described. Molecular oxygen is excited by a photosensitizer and an antenna dye that are dissolved in one of the particles. 1 delta gO2 diffuses to the second particle and initiates a high quantum yield chemiluminescent reaction of an olefin that is dissolved in it. The efficiency of 1 delta gO2 transfer between particles is approximately 3.5%. The technique permits real-time measurement of particle binding kinetics. Second-order rate constants increase with the number of receptor binding sites on the particles and approach diffusion control. By using antibody-coated particles, a homogeneous immunoassay capable of detecting approximately 4 amol of thyroid-stimulating hormone in 12 min was demonstrated. Single molecules of analyte produce particle heterodimers that are detected even when no larger aggregates are formed.  相似文献   
8.
During the 1970s and 1980s, a new approach to the integration of acute and long-term care (LTC) services was conceived and refined at On Lok, an organization in the Chinese community of San Francisco. Since then, On Lok and 10 Federal demonstration sites have tested this model which is today called the Program of All-Inclusive Care for the Elderly (PACE). This program has gained considerable political support and as a result, the 1997 Balanced Budget Agreement establishes PACE as a permanent provider under Medicare. The Federal demonstration of PACE was designed as a voluntary program. By exploiting its voluntary enrollment design, this study analyzes the determinants of program participation within a group of screened applicants. Findings of this study support the theory that the capitated payment structure of PACE creates incentives for program staff to avoid costly individuals. However, home ownership and provider attachment also act as important and significant barriers to enrollment.  相似文献   
9.
This is the first case report of the preoperative diagnosis of a gastric epithelioid leiomyosarcoma by percutaneous needle biopsy. Preoperative diagnosis facilitated curative surgical resection. Patients may present without symptoms or may report symptoms of peptic ulcer disease or gastrointestinal bleeding. Upper gastrointestinal series is the most useful radiological tool for detecting these lesions. Ultrasound and CT play a useful role in documenting the origin of these large masses, as well as their spread. Endoscopy is being used with increasing frequency, but because these are submucosal lesions diagnosis cannot easily be made through the endoscope. Pathologically, these tumors can be subdivided histologically into a benign epithelioid leiomyoma and two varieties of malignant epithelioid leiomyosarcoma. Prognosis correlates with histological features. Complete surgical resection is the treatment of choice. Chemotherapy or radiotherapy have no proven efficacy in treating epithelioid leiomyosarcoma. Unlike most other gastric malignancies, a favorable prognosis follows successful resection.  相似文献   
10.
1. "Association" neurons in the posterior middle suprasylvian gyrus of cat were found to be predominantly polysensory, with 82% of the units in the chloralose-anesthetized preparation responding to auditory, visual, and somatic stimuli. There was no evidence of response differentiation associated with cortical depth distribution. Most units responded with a short-latency response (median 35-60 ms) to all stimulus modalities, with the response to visual stimulation occurring at the shortest latency. Among polysensory cells, almost half responded with equal probability to auditory, visual, and somatic stimulation. The visual stimulus was the most potent for those cells responding with a higher probability to a single modality. Varying degrees of response complexity were noted in some cells in terms of changes in responsivity over time, discharge to stimulus offset, and inhibition of spontaneous activity. The unitary discharge was seen to occur on the negative peak and slope of the locally recorded evoked potential. When only the larger amplitude spikes were analyzed, most of the unitary activity occurred on the negative peak of the evoked potential. Almost half of trimodally responsive cells displayed similar phase relationships between unitary activity and evoked potentials for all three modalities. The absolute refractory period for most cells was from 200 to 300 ms, with relative refractory periods extending up to 30 s...  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