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   492篇
  免费   19篇
  国内免费   14篇
耳鼻咽喉   11篇
儿科学   18篇
妇产科学   8篇
基础医学   64篇
口腔科学   10篇
临床医学   52篇
内科学   89篇
皮肤病学   5篇
神经病学   10篇
特种医学   132篇
外科学   26篇
综合类   9篇
预防医学   60篇
眼科学   4篇
药学   12篇
肿瘤学   15篇
  2021年   3篇
  2020年   1篇
  2019年   1篇
  2018年   4篇
  2017年   3篇
  2016年   3篇
  2015年   9篇
  2014年   9篇
  2013年   9篇
  2012年   7篇
  2011年   16篇
  2010年   8篇
  2009年   21篇
  2008年   15篇
  2007年   23篇
  2006年   21篇
  2005年   18篇
  2004年   17篇
  2003年   8篇
  2002年   9篇
  2001年   7篇
  2000年   3篇
  1999年   15篇
  1998年   22篇
  1997年   27篇
  1996年   25篇
  1995年   10篇
  1994年   17篇
  1993年   8篇
  1992年   9篇
  1991年   4篇
  1990年   6篇
  1989年   11篇
  1988年   12篇
  1987年   13篇
  1986年   14篇
  1985年   16篇
  1984年   5篇
  1983年   17篇
  1982年   18篇
  1981年   15篇
  1980年   10篇
  1979年   3篇
  1978年   7篇
  1977年   13篇
  1976年   7篇
  1975年   1篇
  1974年   2篇
  1972年   2篇
  1969年   1篇
排序方式: 共有525条查询结果,搜索用时 10 毫秒
1.
INTRODUCTION: Limited access to medical care has resulted in large numbers of patients seeking primary care for non-emergent emergency conditions in emergency departments. This influx of patients is contributing to overcrowding and delays in care for patients with emergencies. In response, a system was implemented in which persons with non-emergent medical conditions, following a medical screening examination, did not receive further ED assessment or treatment and instead were referred to community resources. The purpose of this study was to describe the characteristics of individuals who were referred to community-based services, their condition after 72 hours, and their use of follow-up health care services. METHODS: All referred cases (n=225) were reviewed for chief complaint and demographics. Phone contact was attempted after 72 hours to determine the person's condition and if community resources were utilized. RESULTS: Of the 225 cases, 52% were female, with a mean age of 33 years. Their most common chief complaints were extremity problems (16%), toothache (9%), and medication refill (8%). Follow-up phone contact was successful with 82 people (37%) an average of 14 days after their ED visit. The majority (55%) reported their condition had improved; 39%were unchanged, and 6% were worse. Thirty-one people(40%) accessed community resources and 8 (26%) returned to another emergency department. No clinically significant associations were found between patient demographics and use of community resources. DISCUSSION: Most people who were successfully contacted for follow-up and who had come to the emergency department with non-emergent chief complaints did not access community resources and their condition frequently improved. Additional studies, with improved follow-up, are needed before suggesting that referring individuals to community resources is an acceptable practice.  相似文献   
2.
3.
华蟾蜍毒素对离体豚鼠输精管的作用   总被引:3,自引:0,他引:3  
韩永晶  张力  崔荣芬 《药学学报》1992,27(4):252-255
华蟾蜍毒素(华蟾素)使离体豚鼠输精管产生剂量依赖性收缩反应,利血平化豚鼠输精管及冷藏输精管对华蟾素反应减弱。给酚妥拉明、维拉帕米后,输精管对华蟾素反应均受抑制,溴苄胺可使反应潜伏期缩短。结果提示华蟾素收缩输精管反应可能与其促进肾上腺素能神经末稍NA释放有关。  相似文献   
4.
5.
Male genital tract obstructions may result from infections, previous inguinal and scrotal surgery (vasectomy) and congenital bilateral absence of the vas deferens (CBAVD). Microsurgery can sometimes be successful in treating the obstruction. In other cases and in cases of failed surgical intervention, the patient can be treated by microsurgical or percutaneous epididymal sperm aspiration (MESA, PESA) or testicular sperm extraction (TESE) and intracytoplasmic sperm injection (ICSI). We present the results of 39 ICSI procedures for obstructive azoospermia in 24 couples. The aetiology of the obstruction was failed microsurgery in 11 patients, CBAVD in nine and genital infections in four. Sperm retrieval was accomplished via MESA in four cases, PESA in 18 cases and via TESE in 11 cases. TESE was only applied when PESA failed to produce enough spermatozoa for simultaneous ICSI. In six patients, the ICSI procedure was performed with cryopreserved spermatozoa after an initial PESA procedure. Fertilization occurred in 47% of the metaphase II oocytes; embryo transfer was performed in 92% of procedures and resulted in a clinical pregnancy in 13/39 procedures. Ongoing pregnancy was achieved in 10/39 procedures. One pregnancy was terminated early after prenatal investigation showed a cytogenetic abnormality (47,XX+18, Edwards syndrome). The other nine pregnancies resulted in the live birth of 10 children, without any congenital abnormalities. Epididymal and testicular retrieved spermatozoa were successfully used for ICSI to treat obstructive azoospermia, and resulted in an ongoing pregnancy in 10 of 24 couples (41.6%) after 39 ICSI procedures, a success rate of 25.6% per treatment cycle and of 27.7% per embryo transfer.   相似文献   
6.
7.
The importance of maternal infections with Toxoplasma gondii , cytomegalovirus (CMV), Parvovirus B19, respiratory syncytial virus (RSV), and influenza A and B on fetal IgE synthesis was studied in 153 pregnant women. No case of specific IgM activity or viral DNA in cord blood, indicating a congenital infection, was found. From gestational week 15 to delivery, maternal IgG-Ab seroconversion to Parvovirus B19, RSV, influenza A, or influenza B occurred in 47 women. At delivery, serologic signs of past infection with T. gondii were observed in 29 (19%) women, and the corresponding figure for CMV was 117 (77%). The number of women with positive IgG seroconversion during pregnancy or positive IgG-Ab activity toward the studied infectious agents at delivery did not differ significantly among infants with an increased (≥1.3 kU/1; n =51) or with an undetectable (<0.1 kU/l; n =102) cord-blood IgE level. These results show that genetic and other environmental factors probably have a greater influence on fetal IgE synthesis than do maternal infections during pregnancy.  相似文献   
8.
L1 is a neural cell adhesion molecule mainly involved in axon guidance and neuronal migration during brain development. Mutations in the human L1 gene give rise to a complex clinical picture, with mental retardation, neurologic abnormalities and a variable degree of hydrocephalus. Recently, a transgenic mouse model with a targeted null mutation in the L1 gene was generated. These knockout (KO) mice show hypoplasia of the corticospinal tract. Here we have performed further studies of these KO mice including magnetic resonance imaging of the brain, neuropathological analysis and behavioral testing. The ventricular system was shown to be abnormal with dilatation of the lateral ventricles and the 4th ventricle, and an altered shape of the Sylvius aqueduct. Additionally, the cerebellar vermis of the KO mice is hypoplastic. Their exploratory behavior is characterized by stereotype peripheral circling reminiscent of that of rodents with induced cerebellar lesions.   相似文献   
9.
PurposeThe main objectives of this study were to determine (1) whether family communication and school connectedness offer protection against suicidal behaviors in the presence of adverse childhood experiences (ACEs; direct protective effect) and (2) whether family communication or school connectedness buffer the association between ACEs and suicidal behaviors (interacting protective effect) on the multiplicative and additive scales.MethodsData were obtained from a western state's 2019 Youth Risk Behavior Survey that included 5,341 middle school and 4,980 high school participants. Generalized linear models were used to estimate whether family communication and school connectedness offered direct protection against suicidal behaviors or buffered the association between ACEs and suicidal behaviors using adjusted prevalence ratios and corresponding 95% confidence intervals.ResultsFamily communication and school connectedness offered direct protection against suicidal behaviors in the presence of ACEs (a 1-unit higher score was associated with a 32%–42% lower prevalence of suicidal behaviors for middle school youth and a 27%–39% lower prevalence of suicidal behaviors for high school youth). There was evidence that family communication and school connectedness buffered the association between ACEs and suicidal behaviors on the multiplicative scale.ConclusionsThe findings provide support for the development and implementation of interventions that build family communication and school connectedness to reduce suicidal behaviors. Furthermore, screening for trauma and suicidal behaviors is warranted.  相似文献   
10.
The present study comprised 1000 child and young workers in small and medium-size industries in Alexandria, as well as 250 control subjects. Almost all young workers work for more than 40 hours/week and suffer from fatigue. Workers' family needs rather than the lack of family care is the responsible factor for sending the child to work, and the economic problems seem to be the underlying factor for all other problems of child labour. Work improves labourers' socio-economic status and smoking habit, and provides a chance for their personal contacts and interactions, which are reflected on their level of intellectual capabilities; however, it has some impact on their food habits affecting their achievement of balanced diet; and no drug addiction exists among all the studied subjects. Noise and dust represent the main occupational exposures (84.4% and 55.8% respectively), followed by exposure to heat (25.3%), vapors and gases (10.4%) and biological materials (9.0%), and nearly 2/3 of the workers have combined exposures. Work injuries occurred to 18.4% of the workers and 7.4% had more than one injury during employment; however, nearly 1/3 of the injuries required absenteeism off work and/or hospitalization. The injuries have been typically related to industrial operations, occurring mostly to hands and fingers (80.4%), and are mainly attributed to lack of training (63.0%). The health services presented to the workers are very poor. The study has been concluded by recommending making the work safe, free from hazards, and ergonomically fit to children, providing educational and training services, covering young workers by social security, and revising legislation of child labour.  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