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   2433742篇
  免费   196237篇
  国内免费   8219篇
耳鼻咽喉   31965篇
儿科学   80081篇
妇产科学   68200篇
基础医学   339557篇
口腔科学   66636篇
临床医学   220859篇
内科学   489805篇
皮肤病学   57827篇
神经病学   201856篇
特种医学   95985篇
外国民族医学   708篇
外科学   369845篇
综合类   58065篇
现状与发展   4篇
一般理论   830篇
预防医学   195218篇
眼科学   53959篇
药学   170922篇
  6篇
中国医学   5010篇
肿瘤学   130860篇
  2018年   26493篇
  2017年   20511篇
  2016年   23846篇
  2015年   26673篇
  2014年   37593篇
  2013年   56223篇
  2012年   72450篇
  2011年   77590篇
  2010年   47049篇
  2009年   45376篇
  2008年   72032篇
  2007年   76413篇
  2006年   77664篇
  2005年   75366篇
  2004年   71981篇
  2003年   69243篇
  2002年   66285篇
  2001年   118637篇
  2000年   121635篇
  1999年   101299篇
  1998年   29861篇
  1997年   26889篇
  1996年   27642篇
  1995年   27039篇
  1994年   24876篇
  1993年   23394篇
  1992年   80277篇
  1991年   77495篇
  1990年   74410篇
  1989年   70894篇
  1988年   65464篇
  1987年   64128篇
  1986年   60270篇
  1985年   57904篇
  1984年   44167篇
  1983年   37302篇
  1982年   23118篇
  1981年   20652篇
  1980年   19238篇
  1979年   39551篇
  1978年   28322篇
  1977年   23730篇
  1976年   22014篇
  1975年   22811篇
  1974年   27108篇
  1973年   26079篇
  1972年   24344篇
  1971年   22312篇
  1970年   20832篇
  1969年   19382篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
921.
OBJECTIVE: Cancer Care Ontario has recommended a population-based colorectal cancer (CRC) screening program using fecal occult blood testing. Patients who test positive should undergo further investigation, preferably colonoscopy. So far, no studies have been performed to quantify the costs or demands on the health care system at the community level. The number of consultations, colonoscopies and polypectomies, and the corresponding direct medical costs generated by the CRC screening program, between 2006 and 2015 in London, Ontario, were estimated using a decision analysis model in comparison with the population health model. METHODS: A faxed survey study was conducted to examine the current CRC screening practice among family physicians in London. Data from the survey and randomized studies were applied to a decision analysis model, which simulated the steps involved in population-based biennial and annual CRC screening between 2006 and 2015. The number of consultations, colonoscopies and polypectomies, and their associated costs were calculated. RESULTS: For a cohort population of 140,000, between 50 and 74 years of age, in 2006 to 2015, it is estimated that an average of 412 consultations, 463 colonoscopies and 174 polypectomies will be performed per 100,000 screen eligible population per year in biennial screening, and double in annual screening, reflecting an average of 8.7% or 17.6% increase annually in outpatient colonoscopies, respectively, compared with 2003. A mean of $285,000 or $562,000 per year would be required to support the extra consultation and endoscopic procedures generated by the biennial or annual screening. CONCLUSION: Population-based fecal occult blood testing screening for CRC appears to be a manageable strategy if a modest increase in endoscopic resources is allocated.  相似文献   
922.
923.
This was a retrospective observational study of 11 consecutive patients of major primary postpartum haemorrhage (PPH) who had the B-Lynch suture at the time of caesarean section, performed between 1 March 2001 and 31 March 2004 at a teaching hospital in Scotland. Case-note review was performed in 123 patients, who had major primary PPH to identify patients who had B-Lynch sutures at the time of caesarean section. The patient's age, parity, gestation of pregnancy at which the B-Lynch suture was performed, the indication for caesarean section and the cause of primary major PPH were recorded. The operative details, intraoperative and immediate postoperative complications and the need for subsequent hysterectomy were noted. The patients were followed-up with clinic visits at 6 weeks and any further hospital referral for late postoperative complications and whether subsequent successful pregnancy was achieved, were documented. The incidence of major PPH in our centre was 0.5% of the total deliveries, of which 11 cases had the B-Lynch suture applied at the time of caesarean section. The patients were aged between 25 and 38 years old (mean 31 years). Parity ranged from 0 to 1 and the gestational age at which the procedure was performed ranged from 34 to 41 weeks (mean 38 weeks). Ten operations (91%) were performed by senior registrars supervised by the consultant on call and one (9%) case was performed by a consultant on call. All cases had the B-Lynch sutures performed for major primary PPH caused by uterine atony at the time of caesarean section. The weight of the babies delivered ranged between 2,110 - 4,820 g (mean 3,500 g). The total blood loss at surgery ranged from 2,000 - 10,000 ml (mean 3,500 ml). Only three patients (28%) required hysterectomy. All the patients made a good postoperative recovery. The hospital stay ranged from 4 - 24 days (mean 8 days). The patient who remained in hospital for 24 days did so because her baby was admitted into the neonatal unit. All the patients were reviewed 6 weeks postnatally. There was no significant morbidity. A subsequent successful pregnancy has been achieved in one patient.  相似文献   
924.
925.
926.
927.
928.
929.
The literature suggests that pain in the elderly, especially among seniors with dementia, is under-assessed and under-treated.This qualitative study solicited the perspectives of seniors, front-line nursing staff, nursing-home administrators, and informal caregivers of seniors with dementia on the current status of pain assessment and management. The views of these participants complement the research findings reported in the literature. While some of their explanations and potential solutions concerning under-treatment of pain in seniors echo views that have been presented in the literature, the participants also pointed to factors and avenues that have been given less formal consideration (e.g., systemic barriers to effective assessment and treatment of pain).They also highlighted the need for pain-control strategies beyond medication. The implications of these findings are discussed.  相似文献   
930.
OBJECTIVE: To describe the course and outcome of fetuses with absent or reversed end-diastolic (ARED) flow in the umbilical artery (UA) and to examine the influence of prematurity according to gestational age at delivery. METHODS: Sixty pregnancies complicated by ARED flow in the UA were monitored by repeat Doppler measurements of arterial and venous vessels, non-stress tests (cardiotocogram (CTG)) and maternal investigations, and were delivered between 24 and 34 weeks. Fetal outcome was investigated and compared to a control group of appropriate-for-gestational age (AGA) preterm neonates, matched for gestational age. Mortality, birth weight, Apgar scores, postnatal cord arterial pH and need for ventilation were all recorded, as were cases of respiratory distress syndrome, bronchopulmonary dysplasia, persistent ductus arteriosus, necrotizing enterocolitis, intraventricular hemorrhage, periventricular leukomalacia, abnormal neurological findings and those requiring surgical intervention. Additionally, the group of fetuses with ARED flow was divided into three subgroups of different degrees of prematurity (delivery between 24 + 0 and 28 + 6 weeks, delivery between 29 + 0 and 31 + 6 weeks, and delivery after 32 weeks) and compared according to the above parameters. RESULTS: Pre- or postnatal death occurred in 16 cases. Comparing the 44 (61%) that were born alive with the AGA neonates, significant differences were found in birth weight (P < 0.001), arterial pH value (P < 0.001), bronchopulmonary dysplasia (P = 0.002) and intestinal complications (P < 0.01). Prematurity-related complications were: need for ventilation (P = 0.001), respiratory distress syndrome (P < 0.0001), periventricular leukomalacia (P = 0.002) and pathological neurological testing (P = 0.005). CONCLUSIONS: Neonates displaying ARED flow before birth are growth restricted, acidemic at delivery and are at high risk of developing bronchopulmonary dysplasia and intestinal complications. While perinatal mortality seems to be related to abnormal fetal Doppler velocimetry, age at delivery has a significant impact on short-term morbidity. After 32 weeks, morbidity is low and delivery should be considered. It could be speculated from our data that prolongation of pregnancy with Doppler velocimetry monitoring could help to reduce morbidity, although prolongation remains limited in most cases.  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