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   2050篇
  免费   127篇
  国内免费   11篇
耳鼻咽喉   11篇
儿科学   52篇
妇产科学   134篇
基础医学   306篇
口腔科学   28篇
临床医学   153篇
内科学   404篇
皮肤病学   34篇
神经病学   163篇
特种医学   46篇
外国民族医学   1篇
外科学   367篇
综合类   11篇
一般理论   1篇
预防医学   206篇
眼科学   53篇
药学   150篇
中国医学   1篇
肿瘤学   67篇
  2023年   10篇
  2022年   19篇
  2021年   55篇
  2020年   37篇
  2019年   59篇
  2018年   69篇
  2017年   36篇
  2016年   41篇
  2015年   44篇
  2014年   54篇
  2013年   101篇
  2012年   115篇
  2011年   126篇
  2010年   86篇
  2009年   67篇
  2008年   109篇
  2007年   98篇
  2006年   129篇
  2005年   94篇
  2004年   82篇
  2003年   75篇
  2002年   83篇
  2001年   64篇
  2000年   76篇
  1999年   59篇
  1998年   9篇
  1997年   8篇
  1996年   9篇
  1995年   11篇
  1994年   13篇
  1993年   8篇
  1992年   31篇
  1991年   29篇
  1990年   28篇
  1989年   25篇
  1988年   27篇
  1987年   16篇
  1986年   22篇
  1985年   27篇
  1984年   16篇
  1983年   13篇
  1982年   10篇
  1980年   9篇
  1978年   5篇
  1977年   5篇
  1975年   10篇
  1974年   17篇
  1973年   13篇
  1972年   5篇
  1970年   5篇
排序方式: 共有2188条查询结果,搜索用时 15 毫秒
1.

Background

There are well-established relationships between health and homelessness, and shelters can facilitate the transmission of diseases and contribute to their prevention. Adequate environmental health conditions and hygiene behaviors in homeless shelters are fundamental to the health of their clients, a marginalized population. We report the status of environmental health conditions and hygiene behaviors in homeless shelters and associated health outcomes; interventions to improve these conditions, behaviors, and outcomes; and obstacles to improvement.

Methods

PubMed, Web of Science, Scopus, and EBSCOhost were searched for peer-reviewed studies, and additional sources for grey literature. Studies were included if they reported primary data on one or more environmental health condition or hygiene behavior in homeless shelters.

Results

Twenty-eight studies were included in the review. Insufficient ventilation systems, unhygienic bedding, and overcrowding were the most documented environmental health and hygiene deficiencies in homeless shelters, and tuberculosis infections and skin diseases were the most documented associated health outcomes among clients. Studies frequently recommended or described implementation of behavioral and administrative controls, ventilation system improvements, and ultraviolet germicidal irradiation fixtures.

Discussion

Most studies addressed airborne transmission of tuberculosis and were conducted in high-income countries, revealing an imbalance in the literature. Insufficient resources and the transience of clients are barriers to improving hygiene behaviors and environmental conditions in homeless shelters. Further investment and research into ensuring adequate hygiene and environmental health in this setting can protect and promote the health and well-being of people experiencing homelessness.  相似文献   
2.
3.
4.
PURPOSE: This study was undertaken to clarify the importance of bleeding vascular ectasia of the colon as the etiology of massive lower gastrointestinal hemorrhage in patients 40 years of age or younger. METHODS: An otherwise healthy 21-year-old male was admitted to a tertiary medical center with massive lower gastrointestinal hemorrhage. Technetium-labeled red blood cell scan, selective visceral angiography, and colonoscopy identified the source of bleeding as vascular abnormality of the descending colon. Segmental colonic resection was performed. RESULTS: Histologic review of the specimen demonstrated a vascular ectasia. The patient recovered uneventfully and has had no further stigmata of hemorrhage. A review of the literature was undertaken to make clear the significance of vascular ectasia as the source for massive colonic hemorrhage in the young adult. CONCLUSION: This is the first report that documents histologically a vascular ectasia as the source of massive lower gastrointestinal hemorrhage in an otherwise healthy patient less than 40 years of age. Vascular ectasia is an uncommon cause of lower gastrointestinal hemorrhage in the young adult.The Chief, Bureau of Medicine and Surgery, Navy Department, Washington, DC, Clinical Investigation Program sponsored this report #84-16-1968-532, as required by HSETCINST 6000.41A. The views expressed in this article are those of the authors and do not reflect the official policy or position of the Department of the Navy, Department of Defense, or the United States Government.  相似文献   
5.
The literature on therapeutic intrauterine insemination (TII) is confused because of lack of homogeneity in case selection, differences in executing the procedural steps, and the manner of evaluating and reporting results. This review compares results from Norfolk with those in the English literature. Special emphasis has been placed on separately analyzing each step of the procedure and presenting results of different authors in a comparable fashion. Including all etiologic factors and types of cycles, the term pregnancy rate per cycle was 3% for Norfolk, 2.6% to 6.2% elsewhere. Patients receiving TII in stimulated cycles did significantly better than those receiving TII in natural cycles, in terms of total pregnancy rate per cycle (p = 0.002). In male factor infertility, term pregnancy rate per cycle was 1.1% in Norfolk, 4.7% to 6.2% elsewhere (perhaps because of stricter criteria in Norfolk). In cervical factor infertility, term pregnancy rate per cycle was 4.5% in Norfolk, 2.7% to 11% for others. For unexplained infertility, Norfolk had 5.8% term pregnancy rate per cycle for natural cycles, 8.3% for stimulated cycles. Best published prospective results were 23% for stimulated cycles. TII seems to have a very low efficiency rate judging from term pregnancy rates per cycle. There are clear data indicating the need for redefining the indications.  相似文献   
6.
OBJECTIVE: The purpose of this study was to investigate the sperm-binding potential of human oocytes at different stages of nuclear maturation under hemizona assay (HZA) conditions. DESIGN: This was a prospective study designed in a blinded fashion. SETTING: Academic research environment approved by the Institutional Review Board. PATIENTS: Surplus oocytes, donated by patients undergoing in vitro fertilization therapy after gonadotropin stimulation, were analyzed. Semen from a fertile donor was used in all assays. INTERVENTIONS: Five groups of oocytes were considered: (1) immature, prophase I; (2) metaphase I; (3) metaphase II; (4) inseminated, unfertilized metaphase II; and (5) immature, prophase I oocytes matured in vitro to metaphase II. Oocytes were stored in salt solution (pH 7.2) and microbisected before assay. MAIN OUTCOME MEASURE(s): Tight binding of sperm to the zona pellucida under HZA conditions was evaluated after 4 hours of gametes coincubation. RESULTS: Metaphase II oocytes (groups 3 and 4) had significantly higher binding than other groups (P = 0.0001). The mean value of the difference between the two halves (hemizona) was not significant, thus showing a small intra-assay variation for all maturational stages. CONCLUSIONS: Full meiotic competence of human oocytes is associated with an increased zona pellucida-binding potential.  相似文献   
7.
Fucoidin and heparin sulfate inhibit binding of human sperm to the human zona pellucida under hemizona assay (HZA) conditions. Here we used the HZA to further assess tight sperm binding with/without preincubation of the sperm with other sulfated and nonsulfated glycoconjugates and charged polymers. Fucoidin significantly inhibited binding compared with controls (greater than 75% inhibition), even if sperm were washed after preincubation with the saccharide. Dextran sulfate also produced significant inhibition, although to a lesser extent (54% inhibition). Chondroitin sulfates A and B, heparin, and dextran did not affect binding. Sodium sulfate and polyglutamic acid did not affect HZA results; polyphosphates produced only moderate inhibition. The potent inhibitory effect of the sulfated carbohydrates fucoidin and dextran is probably competitive (receptor-ligand type) in nature. However, the lack of significant effects of simple charged molecules (nonspecific effects) suggests that the degree of sulfation (charge) may not be crucial to its inhibitory action.  相似文献   
8.
9.
10.
Minor experience still exists in our country with regard to the use of valve homografts in cardiac surgery. Only a few implantations have been performed in cases of right ventricular outflow tract reconstruction in addition to our own experience in cases of infective endocarditis of the aortic valve. We present a case of aortic valve replacement by using an antibiotic-sterilized fresh pulmonary valve autograft. The case is described and the possible advantages of the use of pulmonary allografts in the aortic position are discussed.  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