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   1379427篇
  免费   99821篇
  国内免费   2080篇
耳鼻咽喉   19963篇
儿科学   45599篇
妇产科学   40229篇
基础医学   202973篇
口腔科学   38822篇
临床医学   116959篇
内科学   269707篇
皮肤病学   29647篇
神经病学   110323篇
特种医学   54533篇
外国民族医学   366篇
外科学   213436篇
综合类   27040篇
现状与发展   1篇
一般理论   338篇
预防医学   98478篇
眼科学   31319篇
药学   104857篇
  1篇
中国医学   2655篇
肿瘤学   74082篇
  2018年   14200篇
  2017年   10887篇
  2016年   12612篇
  2015年   13805篇
  2014年   18382篇
  2013年   28616篇
  2012年   39063篇
  2011年   42167篇
  2010年   24732篇
  2009年   22429篇
  2008年   41292篇
  2007年   44551篇
  2006年   44818篇
  2005年   43969篇
  2004年   42222篇
  2003年   41329篇
  2002年   40691篇
  2001年   61782篇
  2000年   64238篇
  1999年   53321篇
  1998年   15327篇
  1997年   13720篇
  1996年   13774篇
  1995年   12934篇
  1994年   12321篇
  1993年   11430篇
  1992年   41493篇
  1991年   40811篇
  1990年   40322篇
  1989年   39137篇
  1988年   36489篇
  1987年   35778篇
  1986年   34079篇
  1985年   32650篇
  1984年   24397篇
  1983年   21260篇
  1982年   12831篇
  1981年   11354篇
  1979年   22991篇
  1978年   16208篇
  1977年   14090篇
  1976年   13267篇
  1975年   14515篇
  1974年   16995篇
  1973年   16328篇
  1972年   15516篇
  1971年   14438篇
  1970年   13412篇
  1969年   12900篇
  1968年   12147篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
1.
2.
3.
4.
5.
6.
Vaccination is a vital health care initiative to prevent individual and population infection. To increase vaccination rates the federal government implemented the ‘No Jab, No Pay’ policy, where eligibility for several government benefits required children to be fully vaccinated by removing ‘conscientious objections’ and expanding the age range of children whose families receive benefits. This study assesses the impact of this policy at a local area within a single medical practice community in NSW, Australia. A retrospective clinical audit was performed between 2012 and 2017 on a single general practice's vaccination records for children ≤19 years. Catch-up vaccinations were assessed based on age at vaccination. Incidence of catch-up vaccinations was assessed for each of four years before and two years after the implementation of the ‘No Jab, No Pay’ policy in January 2016, along with the age of children and vaccination(s) given. Catch-up vaccinations were assessed temporally either side of implementation of ‘No Jab, No Pay’. Comparing the average annual vaccination catch-up incidence rate of 6.2% pre-implementation (2012–2015), there was an increase to 9.2% in 2016 (p < .001) and 7.8% in 2017 (p = .027). Secondary outcome measurement of catch-up vaccination incidence rates before (2012–2015) and after (2016–2017) ‘No Jab, No Pay’ implementation showed statistically significant increases for children aged 8–11 years (3.2%–5.6%, p = .038), 12–15 years (7.5%–14.7%, p < .001) and 16–19 years (3.3%–10.2%, p < .001) along with a statistically significant reduction in children aged 1–3 years (11.4%–6.2%, p = .015). Also, catch-up rates for DTPa significantly increased after program implementation. This study demonstrates that the Australian federal government vaccination policy ‘No Jab, No Pay’ was coincident with an increase in catch-up vaccinations within a rural NSW community served by one medical practice, especially for older children.  相似文献   
7.
Tamoxifen prevents recurrence of breast cancer and is suggested for preventive risk-reducing therapy. Tamoxifen reduces mammographic density, a proxy for therapy response, but little is known about its effects in remodelling normal breast tissue. Our study, a substudy within the double-blinded dose-determination trial KARISMA, investigated tamoxifen-specific changes in breast tissue composition and histological markers in healthy women. We included 83 healthy women randomised to 6 months daily intake of 20, 10, 5, 2.5, 1 mg of tamoxifen or placebo. The groups were combined to “no dose” (0-1 mg), “low-dose” (2.5-5 mg) or “high-dose” (10-20 mg) of tamoxifen. Ultrasound-guided biopsies were collected before and after tamoxifen exposure. In each biopsy, epithelial, stromal and adipose tissues was quantified, and expression of epithelial and stromal Ki67, oestrogen receptor (ER) and progesterone receptor (PR) analysed. Mammographic density using STRATUS was measured at baseline and end-of-tamoxifen-exposure. We found that different doses of tamoxifen reduced mammographic density and glandular-epithelial area in premenopausal women and associated with reduced epithelium and increased adipose tissue. High-dose tamoxifen also decreased epithelial ER and PR expressions in premenopausal women. Premenopausal women with the greatest reduction in proliferation also had the greatest epithelial reduction. In postmenopausal women, high-dose tamoxifen decreased the epithelial area with no measurable density decrease. Tamoxifen at both low and high doses influences breast tissue composition and expression of histological markers in the normal breast. Our findings connect epithelial proliferation with tissue remodelling in premenopausal women and provide novel insights to understanding biological mechanisms of primary prevention with tamoxifen.  相似文献   
8.
Troppmair  Teresa  Egger  J.  Krösbacher  A.  Zanvettor  A.  Schinnerl  A.  Neumayr  A.  Baubin  M. 《Der Anaesthesist》2022,71(4):272-280
Die Anaesthesiologie - Die Qualität eines Rettungssystems zeichnet sich auch durch den effizienten Einsatz seiner personellen und Fahrzeugressourcen aus. So können im berechtigten Fall...  相似文献   
9.
10.
G. Berlin  M. Hammar  L. Tapper 《Platelets》2019,30(4):473-479
Platelets are needed to prevent or arrest bleeding and aggregate at the site of injury upon vascular damage. Platelets express receptors for estrogens which might affect the function of the platelets and their hemostatic ability. The aim was to identify possible differences in platelet function related to age, gender, and phases of the menstrual cycle by use of impedance aggregometry with Multiplate. In the first part of the study, platelet function was assessed in 60 healthy individuals (30 men and 30 women) in each of three age groups (20–25, 40–45, and 60–65 years). In the second part of the study, the platelet function was analyzed on four occasions during the menstrual cycle in women without oral contraceptives (OCs) (n = 17) and compared to 19 women on OCs and 18 men of similar age (20–40 years). For the women on OCs, aggregation was analyzed once during the tablet-free week and once late during the period with OCs. The men were sampled once. Women of younger age (<45 years) had significantly higher agonist-induced aggregation response than both men and post-menopausal women (60–65 years). The agonist-induced aggregation response did not differ between phases of the menstrual cycle or OC use. The results suggest that estradiol and/or progesterone affect spontaneous aggregation since it was found to be lowest in the mid-luteal phase. Spontaneous aggregation was significantly lower in women on OCs than in both men and women without OCs. Our findings indicate that fertile age is associated with higher aggregation response capacity of the platelets, possibly to prevent excessive bleeding during menstruation, but this response capacity is not altered during the menstrual cycle or by use of OCs.  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