首页 | 官方网站   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   26042篇
  免费   1340篇
  国内免费   250篇
医药卫生   27632篇
  2024年   18篇
  2023年   209篇
  2022年   207篇
  2021年   772篇
  2020年   486篇
  2019年   642篇
  2018年   764篇
  2017年   589篇
  2016年   722篇
  2015年   784篇
  2014年   998篇
  2013年   1372篇
  2012年   2120篇
  2011年   2080篇
  2010年   1220篇
  2009年   1093篇
  2008年   1906篇
  2007年   1802篇
  2006年   1648篇
  2005年   1659篇
  2004年   1520篇
  2003年   1344篇
  2002年   1241篇
  2001年   157篇
  2000年   109篇
  1999年   161篇
  1998年   219篇
  1997年   200篇
  1996年   154篇
  1995年   183篇
  1994年   149篇
  1993年   139篇
  1992年   91篇
  1991年   76篇
  1990年   89篇
  1989年   55篇
  1988年   46篇
  1987年   38篇
  1986年   50篇
  1985年   55篇
  1984年   60篇
  1983年   44篇
  1982年   51篇
  1981年   32篇
  1980年   44篇
  1979年   27篇
  1978年   15篇
  1977年   16篇
  1975年   19篇
  1974年   20篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
12.
13.
14.
15.
16.
ABSTRACT

Introduction: Steroid hormones are responsible for specific changes in the endometrium during the menstrual cycle, when they are sequentially secreted and, because of this, in the early days sequential combined oral contraceptive regimens were utilized. The same basic concept has been utilized with multi-phasic regimens, in order to produce endometrial pictures mimicking the normal cycle.

Areas covered: The Endometrial effects of progestins and estrogens; combined monophasic high- (50 μg), medium- (30 μg), low- (20 μg), ultralow- (15 μg) estrogen content; sequential regimens; multiphasic combinations; treatment schedules.

Cervical effects of combined high-dose and sequential combinations, including evidence for an increase in malignant lesions.

Expert opinion: Overall, combined oral contraceptives (COCs) inhibit normal proliferative changes and the endometrium becomes thin, narrow, with widely spaced glands and pre-decidual changes in the stroma. During the first few cycles the progestin induces a coexistence of proliferative and secretory features; with time, the picture changes because the progestin induces a down-regulation of estrogen receptors, resulting in tortuous glands similar to those in the secretory phase, but characterized by a quiescent, atrophic glandular epithelium.

In the cervical epithelium, under the influence of high-dose COCs, endocervical glands became hypersecretory and in some instances, distinctive type of atypical polypoid endocervical hyperplasia is found.  相似文献   
17.

Background

Total ankle replacement (TAR) represents an alternative to fusion for the treatment of end-stage ankle osteoarthritis. The aim of the present study was to retrospectively assess the frequency of infections between TARs with anterior and lateral transfibular approach at 12-months follow-up.

Methods

81 TARs through an anterior approach and 69 TARs through a lateral approach were performed between May 2011 and July 2015. We compared surgical time and tourniquet time, as well as superficial and deep infections frequency during the first 12 postoperative months.

Results

In the anterior approach group, there were 3 (3.7%) deep infections and 4 (4.9%) superficial wound infections. In the lateral approach group, there were 1 (1.4%) deep infection and 2 superficial wound infections (2.9%). There were not statistically significant differences between the groups. There was a significant difference between anterior approach (115 minutes) and lateral approach group (179 minutes) in terms of surgical time (P < 0.001).

Conclusions

The frequency of superficial and deep periprosthetic infections during the first postoperative year was not significantly different in the lateral approach group compared to the anterior approach group, despite the significantly longer surgical time in the lateral transfibular approach group.  相似文献   
18.
19.
Summary:  Purpose: To identify a specific neuropsychological profile associated with myoclonic astatic epilepsy (MAE) and Lennox-Gastaut syndrome (LGS).
Methods: Seven patients diagnosed with MAE and four patients diagnosed with LGS were selected from patients referred to our Child Neurology Unit. The patients were assessed both clinically (awake, sleep, Holter EEG, seizures frequency, and semiology) and neuropsychologically (IQ, language, attention, visuospatial and visuomotor abilities, and behavior). One representative case of each syndrome is presented here.
Results: The clinical picture of the MAE patient resembled that of an MAE condition associated with transitory epileptic encephalopathy. The neuropsychological findings suggest that electroclinical anomalies can temporarily affect cognitive and behavioral functioning. Early effective antiepileptic drug (AED) treatment was found to improve cognitive outcome. In contrast, LGS was associated with mental retardation, which persisted after seizure control.
Conclusions: At present, it remains difficult to delineate a precise neuropsychological profile associated with MAE and LGS. The cognitive outcome of MAE is variable and depends on the clinical pattern. With regard to LGS, the hypothesis of a genetic predisposition underlying both the epilepsy and the mental retardation is still valid. Alternatively, exposure to subclinical electrophysiological anomalies during a critical period of cerebral development may be responsible for the mental retardation. At the time the clinical manifestations appear, drug treatment, even if effective, would have only limited impact on cognitive outcome. However, early multidisciplinary intervention may help to improve behavior and communicative abilities, enhancing the quality of life of these children and their families.  相似文献   
20.
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-23

京公网安备 11010802026262号