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   45416篇
  免费   3368篇
  国内免费   135篇
耳鼻咽喉   596篇
儿科学   1139篇
妇产科学   552篇
基础医学   5682篇
口腔科学   478篇
临床医学   4759篇
内科学   9151篇
皮肤病学   493篇
神经病学   4479篇
特种医学   1779篇
外科学   8739篇
综合类   349篇
现状与发展   1篇
一般理论   56篇
预防医学   3757篇
眼科学   801篇
药学   2847篇
中国医学   34篇
肿瘤学   3227篇
  2024年   61篇
  2023年   479篇
  2022年   854篇
  2021年   2061篇
  2020年   1069篇
  2019年   1713篇
  2018年   2066篇
  2017年   1449篇
  2016年   1468篇
  2015年   1620篇
  2014年   2328篇
  2013年   2753篇
  2012年   4352篇
  2011年   4243篇
  2010年   2229篇
  2009年   1881篇
  2008年   2967篇
  2007年   3071篇
  2006年   2582篇
  2005年   2303篇
  2004年   2017篇
  2003年   1694篇
  2002年   1478篇
  2001年   169篇
  2000年   134篇
  1999年   170篇
  1998年   258篇
  1997年   202篇
  1996年   142篇
  1995年   125篇
  1994年   100篇
  1993年   78篇
  1992年   65篇
  1991年   49篇
  1990年   42篇
  1989年   40篇
  1988年   42篇
  1987年   49篇
  1986年   39篇
  1985年   41篇
  1984年   40篇
  1983年   34篇
  1982年   40篇
  1981年   27篇
  1980年   32篇
  1979年   16篇
  1978年   17篇
  1974年   19篇
  1973年   17篇
  1972年   14篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
ABSTRACT

Purpose

New instrument-based techniques for anterior chamber (AC) cell counting can offer automation and objectivity above clinician assessment. This review aims to identify such instruments and its correlation with clinician estimates.  相似文献   
2.

Introduction

In the United States there has been a large increase in participation in lacrosse for both males and females. The purpose of this study was to analyze the number of head injuries, injury rates (calculated using the reported number of participants) and types of head injuries that are seen in emergency departments in the United States.

Methods

We compared injuries between male and female lacrosse participants. This was a retrospective study using a publicly available database produced by the US Consumer Product Safety Commission and information about lacrosse participation from US Lacrosse.

Results

A linear regression was performed and showed a positive correlation between number of head injuries to males and time from 2002 to 2010 (R2?=?0.823; p?=?0.001). While the number of injuries to the head in female lacrosse participants was not significant. There was a negative correlation between the number of head injuries to males from 2010 to 2016 (R2?=?0.800; p?=?0.007), but again, there was no significance for female injury count (R2?=?0.417; p?=?0.117). Other significant differences between head injuries in males and females included the mechanism of injury and the type of injury recorded.

Conclusion

The most recent data from 2010 to 2016, suggest that both males and females have had a decrease in injury rate. However the total number of female head injuries is not significantly decreasing and as the sport continues to grow there will likely be more total head injuries and visits to the emergency department.  相似文献   
3.
Research coordinators in intensive care are a growing specialty about which little is known. This cross-sectional study surveyed the Australia and New Zealand Intensive Care Research Coordinators' Group (n = 49) regarding demographics, education, employment history, job structure, and role content. Most research coordinators were highly qualified and experienced nurses who undertake pharmaceutical trials, multicenter projects, departmental medical and nursing research, audits and data registries, and their own projects.  相似文献   
4.
Traumatic injuries of the elbow are frequent in patients of all ages but are particularly common in young children and adolescents engaged in normal play and athletic competition. Injury may result primarily due to direct trauma or may be secondary to transmission of forces through the elbow following a fall on an outstretched hand. In middle-aged and older individuals, chronic repetitive injuries tend to predominate. In all patients, radiographs remain the initial imaging study of choice. Many patients, however, may need advanced cross-sectional imaging (i.e. MRI, CT, or ultrasound) either at presentation or during the course of their treatment and follow-up. This article reviews the imaging appearance of common acute and chronic traumatic disorders of the elbow.  相似文献   
5.
The reliable change index (RCI) expresses change relative to its associated error, and is useful in the identification of post-operative cognitive dysfunction (POCD). This paper examines four common RCIs that each account for error in different ways. Three rules incorporate a constant correction for practice effects and are contrasted with the standard RCI that had no correction for practice. These rules are applied to 160 patients undergoing coronary artery bypass graft (CABG) surgery who completed neuropsychological assessments preoperatively and 1 week post-operatively using error and reliability data from a comparable healthy non-surgical control group. The rules all identify POCD in a similar proportion of patients, but the use of the within subject standard deviation, expressing the effects of random error, as an error estimate is a theoretically appropriate denominator when a constant error correction, removing the effects of systematic error, is deducted from the numerator in a RCI.  相似文献   
6.
Abstract: Background: Few studies have examined in depth the labor progression of multiparas to determine if there is any additional impact of being parous beyond the first birth. The objective of this study was to determine the effect of parity on labor progression in contemporary obstetric practice. Methods: Our sample consisted of all low‐risk women who delivered a term, live‐born infant from January 2002 to March 2004 at a single institution in Delaware, United States (n = 5,589). The median duration of labor by each centimeter of cervical dilation was computed for parity = 0 (n = 2,645); parity = 1 (n = 1,839); parity = 2 (n = 750); and parity = 3 + (n = 355). Results: Multiparas had a significantly faster labor progression from 4 to 10 cm (293, 300, and 313 min, respectively, for parity = 1, parity = 2, and parity = 3 +), compared with nulliparas (383 min for parity = 0), as well as a shorter second stage of labor. However, no significant differences were found in duration of the active phase or the second stage of labor among multiparas. Conclusions: Additional childbearing appears to have no effect of on the progression of labor among multiparous subgroups. The difference in duration of the active phase between nulliparas and multiparas is substantially smaller in a contemporary population. (BIRTH 33:1 March 2006)  相似文献   
7.
Despite significant improvements in the prognosis of acute promyelocytic leukemia brought about by therapeutic advances, understanding of the epidemiology of acute promyelocytic leukemia remains limited. Earlier reports have suggested that Hispanics may have an increased incidence of acute promyelocytic leukemia, but no systematic analysis of national data has yet been reported. We performed a retrospective cohort study, using data from the Surveillance, Epidemiology, and End Results (SEER) Program of the National Cancer Institute from 1992-2001 in order to compare leukemia incidence rates as a function of race and ethnicity. We identified 709 cases of acute promyelocytic leukemia and analyzed incidence rates by race and sex. Hispanics were not found to have greater lifetime incidence rates than whites, with an incidence relative rate (IRR) of 0.86 that of whites (P=0.17). The age distribution among Hispanics was significantly different from non-Hispanic whites, with greater incidence rates for children ages 1-19 years (IRR=1.9, P=0.02) and adult ages 20-44 years (IRR=1.6, P=0.004). Blacks had lower lifetime incidence rates than non-Hispanic whites (IRR=0.75, P=0.04), Hispanics (IRR=0.64, P=0.007), and Asians (IRR=0.67, P=0.03). Asians did not differ from non-Hispanic whites in lifetime or age-specific incidence rates. These results indicate that while US Hispanics do not have greater lifetime incidence rates of acute promyelocytic leukemia, blacks have lower incidence rates of acute promyelocytic leukemia than Hispanics, non-Hispanic whites, and Asians.  相似文献   
8.
FDA’S Perspectives on Cardiovascular Devices   总被引:1,自引:0,他引:1  
The Food and Drug Administration (FDA) decision process for approving or clearing medical devices is often determined by a review of robust clinical data and extensive preclinical testing of the device. The mission statement for the Center for Devices and Radiological Health (CDRH) is to review the information provided by manufacturers so that it can promote and protect the health of the public by ensuring the safety and effectiveness of medical devices deemed appropriate for human use (Food, Drug & Cosmetic Act, §903(b)(1, 2(C)), December 31, 2004; accessed December 17, 2008 ). For high-risk devices, such as ventricular assist devices (VADs), mechanical heart valves, stents, cardiac resynchronization therapy (CRT) devices, pacemakers, and defibrillators, the determination is based on FDA’s review of extensive preclinical bench and animal testing followed by use of the device in a clinical trial in humans. These clinical trials allow the manufacturer to evaluate a device in the intended use population. FDA reviews the data from the clinical trial to determine if the device performed as predicted and the clinical benefits outweigh the risks. This article reviews the regulatory framework for different marketing applications related to cardiovascular devices and describes the process of obtaining approval to study a cardiovascular device in a U.S. clinical trial.  相似文献   
9.
ObjectiveTo assess for the presence of gastric dysmotility in familial and sporadic Parkinson disease (PD).Methods10 subjects with familial Parkinson disease (fPD), 35 subjects with sporadic Parkinson disease (sPD), and 15 controls, all from academic tertiary care movement disorders centers, were studied. fPD was defined as the presence of at least 2 affected individuals within 2–3 consecutive generations in a family. Molecular genetic analysis has not revealed, thus far, any known genomic abnormality in these families. Gastric emptying was assessed by dynamic abdominal scintigraphy over 92 min following ingestion of a solid meal containing 99mTc-labeled colloid of 40 MBq activity. The main outcome measures were gastric emptying half-time and radiotracer activity over the gastric area at 46 and at 92 min.ResultsGastric emptying time was delayed in 60% of subjects with PD. In comparison to mean t1/2 of 38 ± 7 min in controls, mean t1/2 was 58 ± 25 min in fPD (p = 0.02) and 46 ± 25 min in sPD (p = 0.10). Both fPD and sPD groups included subjects with delayed gastric emptying at an early stage of disease.ConclusionsPatients with fPD showed significantly delayed gastric emptying in comparison to normal age-matched individuals. Further studies of gastrointestinal dysfunction in PD, particularly fPD, are warranted.  相似文献   
10.
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