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   2528篇
  免费   205篇
  国内免费   10篇
耳鼻咽喉   22篇
儿科学   95篇
妇产科学   46篇
基础医学   445篇
口腔科学   52篇
临床医学   283篇
内科学   513篇
皮肤病学   15篇
神经病学   144篇
特种医学   50篇
外科学   371篇
综合类   21篇
预防医学   219篇
眼科学   33篇
药学   123篇
中国医学   1篇
肿瘤学   310篇
  2023年   24篇
  2022年   21篇
  2021年   33篇
  2020年   43篇
  2019年   48篇
  2018年   50篇
  2017年   51篇
  2016年   61篇
  2015年   46篇
  2014年   51篇
  2013年   111篇
  2012年   95篇
  2011年   135篇
  2010年   67篇
  2009年   68篇
  2008年   104篇
  2007年   116篇
  2006年   146篇
  2005年   124篇
  2004年   116篇
  2003年   74篇
  2002年   115篇
  2001年   78篇
  2000年   60篇
  1999年   53篇
  1998年   48篇
  1997年   23篇
  1996年   31篇
  1995年   35篇
  1994年   22篇
  1993年   22篇
  1992年   62篇
  1991年   50篇
  1990年   40篇
  1989年   42篇
  1988年   42篇
  1987年   33篇
  1986年   54篇
  1985年   50篇
  1984年   46篇
  1983年   32篇
  1982年   20篇
  1980年   15篇
  1979年   28篇
  1978年   14篇
  1977年   18篇
  1975年   16篇
  1974年   14篇
  1973年   13篇
  1972年   14篇
排序方式: 共有2743条查询结果,搜索用时 31 毫秒
91.
Background: Numerous studies have demonstrated sensory gating deficits in schizophrenia. However, only a few longitudinal studies report on the effects of antipsychotic treatment on sensory gating deficits and their results are inconsistent. In the present study, P50 suppression and its neural generators were investigated in antipsychotic-naïve first-episode patients with schizophrenia before and after 6 months of treatment with quetiapine. Methods: Thirty-four antipsychotic-naïve first-episode schizophrenia patients and age and gender matched healthy controls were tested in an auditory sensory gating paradigm at baseline and after 6 months. During this period, the patients were treated with quetiapine, while controls received no treatment. Sixteen patients completed the study. Results: Patients showed significant reduced P50 suppression compared with controls at baseline but not at follow-up. Furthermore, a significant positive correlation between baseline P50 suppression and dose of quetiapine at follow-up was found. P50 suppression in patients receiving above median dosages of quetiapine increased significantly from baseline to follow-up. At baseline, a frontocentral source was significantly more active in patients than in controls at the time of the testing stimulus. Conclusions: The present findings suggest that P50 suppression deficits are already present at an early stage of schizophrenia. Furthermore, particularly those patients with more severe gating deficits appeared to need higher dosages of quetiapine, although their clinical symptoms did not seem to indicate this. Quetiapine treatment significantly improved these gating deficits. Furthermore, a frontocentral source in the brain appeared to be involved in the deficient P50 gating of the patients.  相似文献   
92.

Summary

Knowledge of risk factors for hip fracture among very old people is limited. Walking indoors with help from ≤1 person, Parkinson’s disease, currently smoking, delirium in the previous month, underweight, and age were associated with increased risk of hip fracture and could be important for preventive strategy development.

Introduction

The purpose of this study is to investigate risk factors for hip fracture among a representative sample of very old people.

Methods

In total, 953 participants from the Umeå 85+/Gerontological Regional Database population-based cohort study were interviewed and assessed during home visits. Associations of baseline characteristics with hip fracture during the maximum 5-year follow-up period were analyzed using Cox proportional hazards regression.

Results

Participants had a mean age of 89.3?±?4.7 years; 65.8 % were women, 36.8 % lived in residential care facilities, 33.6 % had dementia, and 20.4 % had histories of hip fracture. During a mean follow-up period of 2.7 years, 96 (10.1 %) individuals sustained hip fracture. Walking indoors with help from no more than one person (hazard ratio [HR]?=?8.57; 95 % confidence interval [CI], 1.90–38.71), Parkinson’s disease (HR?=?5.12; 95 % CI, 1.82–14.44), currently smoking (HR?=?4.38; 95 % CI 2.06–9.33), delirium in the previous month (HR?=?2.01; 95 % CI, 1.15–3.49), underweight (body mass index <22; HR?=?1.74, 95 % CI, 1.09–2.77), and age (HR?=?1.09; 95 % CI, 1.04–1.14) were associated independently with an increased risk of hip fracture. Hip prosthesis at baseline decreased the risk of hip fracture (HR?=?0.37; 95 % CI, 0.15–0.91), but only for those with bilateral hip prostheses.

Conclusions

Seven factors were associated independently with incident hip fracture during follow-up in this sample of very old people. These factors could have important clinical implications in identifying persons at high risk of hip fracture, as well as in the development of effective preventive strategies.
  相似文献   
93.

Purpose

The diagnosis of pediatric appendicitis is still a challenge, resulting in perforation and negative appendectomies. The aim of this study was to evaluate novel biomarkers in urine and to use the most promising biomarkers in conjunction with the Pediatric Appendicitis Score (PAS), to see whether this could improve the accuracy of diagnosing appendicitis.

Methods

A prospective study of children with suspected appendicitis was conducted with assessment of PAS, routine blood tests, and measurements of four novel urinary biomarkers: leucine-rich α-2-glycoprotein (LRG), calprotectin, interleukin 6 (IL-6), and substance P. The biomarkers were blindly determined with commercial ELISAs. Urine creatinine was used to adjust for dehydration. The diagnosis of appendicitis was based on histopathological analysis.

Results

Forty-four children with suspected appendicitis were included, of which twenty-two (50 %) had confirmed appendicitis. LRG in urine was elevated in children with appendicitis compared to children without (p < 0.001), and was higher in children with gangrenous and perforated appendicitis compared to those with phlegmonous appendicitis (p = 0.003). No statistical significances between groups were found for calprotectin, IL-6 or substance P. LRG had a receiver operating characteristic area under the curve of 0.86 (95 % CI 0.79–0.99), and a better diagnostic performance than all routine blood tests. LRG in conjunction with PAS showed 95 % sensitivity, 90 % specificity, 91 % positive predictive value, and 95 % negative predictive value.

Conclusion

LRG, adjusted for dehydration, is a promising novel urinary biomarker for appendicitis in children. LRG in combination with PAS has a high diagnostic performance.
  相似文献   
94.

Background and Aim

Swedish health registries are common sources of data for studies on the effects of obesity surgery, and there is a need to assess the quality of data in these registries. The aim of this study was to validate the registration of obesity surgery in the National Patient Registry (NPR) and the Scandinavian Obesity Surgery Registry (SOReg).

Method

We randomly selected 962 out of 8501 registrations of obesity surgery in 2011 from the NPR and SOReg. Registered surgical procedures in the NPR and SOReg were compared to the medical records, and concordance was analyzed by calculating positive predictive value (PPV) with 95 % confidence interval (CI).

Results

We received 938 (98 %) medical records for manual review. The overall PPV for obesity surgery was high in the NPR (PPV 97.0; 95 % CI 95.6–98.4) and even higher in SOReg (PPV 99.7; 95 % CI 99.3–100). Accuracy was higher for gastric bypass surgery than for other types of obesity surgery. Registrations that were misclassified as obesity surgery (n?=?44) included reoperations due to complications or reconstruction to normal anatomy after previous obesity surgery (n?=?11) and endoscopic procedures (n?=?10).

Conclusion

Obesity surgery registrations in the NPR and SOReg have high accuracy and are reliable sources of data to identify patients having undergone obesity surgery. When it is of importance to distinguish between specific surgical procedures, non-gastric bypass surgeries in the NPR should ideally be supplemented with data from other sources.
  相似文献   
95.

Purpose

To investigate which type of hernia that has the highest risk of a recurrence after a primary Lichtenstein repair.

Methods

Male patients operated on with a Lichtenstein repair for a primary direct or indirect inguinal hernia and with a TEP for a later recurrence, with both operations recorded in the Swedish Hernia Register (SHR), were included in the study. The study period was 1994–2014.

Results

Under the study period, 130,037 male patients with a primary indirect or direct inguinal hernia were operated on with a Lichtenstein repair. A second operation in the SHR was registered in 2236 of these patients (reoperation rate 1.7 %). TEP was the chosen operation in 737 in this latter cohort. The most likely location for a recurrence was the same as the primary location. If the recurrences change location from the primary place, we recognized that direct hernias had a RR of 1.51 to having a recurrent indirect hernia compared to having a direct recurrence after an indirect primary hernia repair.

Conclusions

Recurrent hernias after Lichtenstein are more common on the same location as the primary one, compared to changing the location.
  相似文献   
96.
In Germany, approximately 227,000 women and 249,000 men developed cancer in 2014, and nearly 223,000 patients died from the disease that year. Many cancers are curable or have a very good prognosis when they are diagnosed at an early stage. This is where the concept of early detection examinations comes into play.This article describes the current conditions of and participation in examinations for the early detection of cervical, breast, skin, prostate, and colon cancer as provided by Germany’s statutory health services. Participation was derived from claims data from the statutory health insurance system as well as from Germany’s mammography screening program (MSP). The survey “German Health Update” (GEDA 2014/2015-EHIS) served as an additional data source. According to the claims data and considering the intended intervals, participation quotas among insured persons who are entitled to participate lie between 16% (colonoscopy) and 48% (Pap test). In 2015, 51.5% of invited women participated in the MSP. The results according to self-reports of the GEDA survey lie in part substantially higher. The results according to the claims data, the MSP, as well as the self-reports suggest that a large part of the population utilizes the examinations. Colon and cervical cancer examinations will be expanded as organized and quality-assured early detection programs with regular invitations and information on benefits and risks. These efforts should contribute to reaching eligible people who have thus far not participated.  相似文献   
97.
Attention deficit hyperactivity disorder (ADHD) is a common developmental disorder. The present study tested the hypotheses that children with ADHD, particularly those exhibiting severe hyperactivity and impulsivity, have a different stress reaction (measured by salivary cortisol) during a dental recall visit and are more dentally anxious than children in a control group. Eighteen children with ADHD and a control group of 71 children, all 13 yr of age, underwent a clinical dental examination and completed the Corah Dental Anxiety Scale (CDAS). Four saliva samples were gathered for analysis of cortisol: one prior to dental examination, one after, and two the following morning. The subgroup ADHD with hyperactivity/impulsivity had statistically significantly lower cortisol levels than the control group 30 min after awakening. When cortisol values were plotted on a timeline, this subgroup always had lower cortisol concentrations than children in the control group. There was a significant correlation between CDAS scores and cortisol concentrations prior to the dental examination in both the ADHD and the control group. Behavioral expressions of anxiety in children with ADHD may be different from those in other children, not only due to the characteristics of their disorder, but also because of lower stress reactivity.  相似文献   
98.
99.
100.
Although the use of induction therapy has reduced the risk of acute rejection after heart transplantation, its use may be associated with other adverse outcomes. We aimed to examine the effect of no induction (NoInd), induction with basiliximab (BAS), or induction with antithymocyte globulin (ATG) on outcome after heart transplantation. We analyzed data from the International Society for Heart and Lung Transplantation (ISHLT) registry for adult heart transplants performed between 2000 and 2013. The primary outcome was cumulative all-cause mortality, and the secondary outcome was cause-specific death. We identified 27 369 transplants whose recipients received NoInd (n = 15 688), ATG (n = 6830), or BAS (n = 4851). Over a median follow-up of 1497 days, overall 30-day mortality was 5% and 1-year mortality was 11%. Survival after transplant was similar in patients treated with NoInd compared with ATG. The survival was improved using NoInd compared with BAS (log-rank P = .040), adjustment HR = 1.11 (95% CI, 1.04-1.19). Compared to NoInd, BAS was associated with higher risk of graft failure-related deaths, HR = 1.27 (95% CI, 1.02-1.58), and ATG was associated with higher risk of malignancy-related deaths, HR = 1.18 (95% CI, 1.01-1.39). Survival of patients who received NoInd was similar to ATG and better compared with BAS. Further, the use of ATG may be associated with increased malignancy-related mortality, compared with NoInd.  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