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   6777篇
  免费   326篇
  国内免费   41篇
耳鼻咽喉   110篇
儿科学   206篇
妇产科学   119篇
基础医学   928篇
口腔科学   445篇
临床医学   515篇
内科学   1386篇
皮肤病学   164篇
神经病学   470篇
特种医学   252篇
外科学   899篇
综合类   33篇
一般理论   2篇
预防医学   647篇
眼科学   205篇
药学   408篇
中国医学   48篇
肿瘤学   307篇
  2023年   49篇
  2022年   110篇
  2021年   200篇
  2020年   132篇
  2019年   170篇
  2018年   213篇
  2017年   160篇
  2016年   175篇
  2015年   207篇
  2014年   280篇
  2013年   326篇
  2012年   483篇
  2011年   459篇
  2010年   295篇
  2009年   222篇
  2008年   331篇
  2007年   334篇
  2006年   317篇
  2005年   295篇
  2004年   284篇
  2003年   271篇
  2002年   183篇
  2001年   144篇
  2000年   143篇
  1999年   133篇
  1998年   68篇
  1997年   61篇
  1996年   59篇
  1995年   62篇
  1994年   38篇
  1993年   42篇
  1992年   80篇
  1991年   73篇
  1990年   80篇
  1989年   60篇
  1988年   75篇
  1987年   69篇
  1986年   58篇
  1985年   61篇
  1984年   34篇
  1983年   26篇
  1982年   24篇
  1981年   17篇
  1980年   18篇
  1979年   22篇
  1978年   15篇
  1977年   15篇
  1975年   20篇
  1973年   16篇
  1972年   16篇
排序方式: 共有7144条查询结果,搜索用时 15 毫秒
71.
Intervertebral disc herniation is a rare condition in childhood and adolescence, although some cases have already been reported in the literature. We present the case of a 15 year-old-girl with low back pain and scoliosis. She had no previous history of trauma or collagen diseases. MRI showed L4-L5 and L5-S1 disc herniations and no further bone and structural changes. After two level discectomy, pain ceased and scoliosis improved, without further treatment. Based on her evolution and on what has already been reported in literature, we consider that scoliosis associated with disc herniation in young patients is most likely to be only an anthalgic position, not indicative of further structural changes.  相似文献   
72.
PURPOSE: To evaluate the effects on extraocular muscles of a skeletal muscle-specific immunotoxin, saporin-mAb 73, as an alternative to botulinum toxin to induce a permanent correction of oculo-facial dystonias or some forms of ocular motility disorders. METHODS: An immunotoxin was prepared with a monoclonal antibody (mAb 73) against acetylcholine receptors of skeletal muscle, linked to saporin, a type 1 ribosome-inactivating protein (RIP) from Saponaria officinalis. Sixteen New Zealand white rabbits were treated with a single injection of immunotoxin directly into the medial rectus muscle of one eye. Four different dosages of 2, 5, 20, or 50 ng saporin-mAb 73 were used. The rabbits were sacrificed at two, 7 and 14 days post-injection. The medial rectus muscle and the retractor bulbi muscle of both the injected and the fellow eyes were taken and serial sections were examined by light microscopy in a blinded manner. RESULTS: Saporin-mAb 73, even at the dosage of 2 ng, brought about focal damage in the extraocular muscles of rabbits without histological changes in adjacent muscles. The histological examination revealed necrotic/apoptotic lesions restricted to the sites of inoculation and largely infiltrated by macrophages. No evident inflammatory reaction was detected at any time and neutrophils were substantially absent. At 14 days after injection, necrosis/apoptosis was still evident and the sclerotic reaction was minimal. CONCLUSIONS: The immunotoxin saporin-mAb 73 injections into the extraocular muscles of rabbits caused focal damage to the muscles. There was no significant inflammatory reaction and muscle fiber loss was present even at the lower doses. Although the lesions were followed for only 14 days, our results suggest that saporin-mAb 73 has potential to cause safe focal muscle damage but longer-term follow-up are needed to investigate the persistence of muscle weakness.  相似文献   
73.
74.
BACKGROUND: Social participation in the health system constitutes one of the basic principles of Brazilian health sector reform. This paper analyses the concepts held by different groups of stakeholders with respect to social participation in health and identifies their opinions on hindering and enabling factors for this participation. METHODS: A qualitative study was conducted using individual interviews (II) and focus groups (FG) with different groups of stakeholders: 135 users (II, GF), 14 community leaders (II, GF), 12 Municipal Health Council (MHC) members (II), 8 policymakers and (II) 37 health personnel (II, GF) were interviewed. A narrative content analysis of the results was conducted. Two municipalities in North-eastern Brazil, Cabo de Santo Agostinho and Camaragibe, made up the area of study. RESULTS: In all groups, a distinction between individual and group participation emerged and reached different levels of elaboration. Many informants' ideas described also their own ways of action. Individual participation concepts and the utilization of health services were predominant among users. Population and institutional factors were identified as obstacles to participation: users and community leaders referred both type of factors, while the health personnel and MHC members put more emphasis on the former. Some informants among the health personnel did not identify any barriers. Policymakers emphasised the lack of political will. The enabling factors mentioned reflected the same logic. CONCLUSIONS: Concepts and perceived hindering factors to participation which were described appear to show different ways of interaction among the diverse stakeholders and the health services. The results point towards a limited effect of the health policy on social participation. Elements that could contribute to an improvement are identified.  相似文献   
75.
A controlled trial of elective intervention with continuous inflating pressure (CIP) was performed in infants with severe hyaline membrane disease who weighed more than 1000 g at birth. Infants entered the trial if their arterial oxygen tension (PaO2) fell below 60 mmHg while breathing a fractional inspired oxygen concentration (F1O2) greater than 0-95. 11 out of 12 infants in the CIP-treated group and 10 out of 12 in the control group survived. 7 treated and 6 control infants required mechanical ventilation. When CIP was started the Pao2 of the treated infants increased, and they breathed high concentrations of oxygen for a significantly shorter period than the control infants. During the 31-month duration of the trial 107 other infants with severe hyaline membrane disease were admitted who did not meet the criteria for entry to the trial. 37 survived after breathing high concentrations of oxygen (F1O2 greater than 0-60) spontaneously without any ventilatory assistance, and the remaining 70 infants were already being ventilated on their arrival in the unit, usually because they had required mechanical ventilation during transfer from other hospitals. The neonatal survival rate for those infants born in this hospital during the study period was 88% (50 out of 57 infants) and for those referred from other hospitals it was 69% (51 out of 74 infants). The maximum further increase in overall survival rate that might have been achieved in our population of infants if CIP had been initiated very early in the course of the illness was 5%--i.e. from 77% (101/131) to 82% (107/131).  相似文献   
76.
This paper describes the synthesis of new cyclic imides obtained by reaction with aminophenazone (CAS 58-15-1, 4-aminoantipyrine) and different anhydrides with further cyclization with acetic acid under reflux. Their structures were confirmed by spectral data (IR and NMR) and elemental analysis. The analgesic activity of the synthesized compounds was investigated initially with the writhing test in mice and the most promising compound, a 3,4-dichloromaleimide derivative (3), was analyzed using other models of nociception. The results indicated that compound 3 exerts potent analgesic activity in mice, being more active than some reference drugs. The analgesia caused by this compound was not reversed by naloxone in the writhing test. In the hotplate test, compound 3 did not increase the latency period of pain induced by thermal stimuli, confirming that it does not interact with opioid systems.  相似文献   
77.
78.
Effects of cholic acid infusion in fetal lambs   总被引:2,自引:0,他引:2  
The effects of prolonged intravenous infusions of cholic acid into fetal lambs are described in this study. The ewes (n = 10, 11 fetuses) were operated on at 114 days of gestation (term = 150 days) by placing plastic catheters in maternal and fetal vessels and in the amniotic cavity. Gestational ages were confirmed after delivery by radiographic examination of the ossification centers of the fetal legs. Infusions of cholic acid (1.6 mumoles/min-1) started 8 to 10 days after surgery in 5 fetuses (including one twin). The remaining 6 fetuses (also including one twin) were infused with 5% dextrose in water. Total plasma bile acids at the beginning of the experiment were similar in both groups (23.8 +/- 6.6 vs. 24.3 +/- 5.7 microM). No significant changes in fetal heart rate, blood pressure, blood gases or pH were detected during the infusion. Meconium-stained amniotic fluid was observed during the third day of infusion in all the fetuses infused with cholic acid and in one control fetus. Fetuses infused with cholic acid were delivered alive 19-26 days before term. The concentration of plasma bile acids in the experimental group at delivery was 829 +/- 305 microM, i.e. significantly higher than that of the control group (24.4 +/- 5.7 microM). Control fetuses (except one twin) were delivered at term. We concluded that cholic acid, even at the high dose infused, is neither lethal nor severely harmful for the fetus. Meconium passage of the fetuses infused with cholic acid, in our experiment, appeared to be related to the stimulatory effect of cholic acid on fetal colonic motility rather than to fetal hypoxia.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
79.
Outbreak of cryptosporidiosis in a day-care center   总被引:10,自引:0,他引:10  
An outbreak of diarrhea due to infection with Cryptosporidium occurred in a day-care center. During a period of 2 months, 23 of 53 (43%) children attending the day-care center and 15 of 104 (14%) household contacts had diarrhea. Cryptosporidium oocysts were identified in 13 of 20 (65%) symptomatic children tested compared with three of 27 (11%) asymptomatic children (chi 2 = 12.56, P less than .001). Enteropathogenic bacteria, enteroviruses, rotavirus, and other protozoan parasites were ruled out as the cause of the diarrhea. A history of diarrhea in household contacts was associated with excretion of Cryptosporidium oocysts by the children. Human-to-human transmission of the infection was suggested by the epidemiology.  相似文献   
80.
Diffuse idiopathic skeletal hyperostosis (DISH) with cervical involvement which cause dysphagia is a rare disease. The otolaryngologist usually can make its diagnostic with a barium swallowing esophagogram. Two patients with DISH are reported.  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