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   1538833篇
  免费   125119篇
  国内免费   6942篇
耳鼻咽喉   18937篇
儿科学   48212篇
妇产科学   40351篇
基础医学   209017篇
口腔科学   40153篇
临床医学   141411篇
内科学   319467篇
皮肤病学   34804篇
神经病学   130970篇
特种医学   63934篇
外国民族医学   287篇
外科学   241202篇
综合类   33708篇
现状与发展   3篇
一般理论   579篇
预防医学   120848篇
眼科学   32931篇
药学   107045篇
  6篇
中国医学   2521篇
肿瘤学   84508篇
  2021年   13143篇
  2019年   13310篇
  2018年   18520篇
  2017年   14393篇
  2016年   16905篇
  2015年   19139篇
  2014年   26994篇
  2013年   39265篇
  2012年   50893篇
  2011年   54218篇
  2010年   33016篇
  2009年   31894篇
  2008年   50031篇
  2007年   53049篇
  2006年   53831篇
  2005年   52297篇
  2004年   49745篇
  2003年   47665篇
  2002年   45257篇
  2001年   67670篇
  2000年   69107篇
  1999年   58289篇
  1998年   19049篇
  1997年   16862篇
  1996年   17589篇
  1995年   17625篇
  1994年   16317篇
  1993年   15333篇
  1992年   47881篇
  1991年   46467篇
  1990年   44575篇
  1989年   42378篇
  1988年   39289篇
  1987年   38564篇
  1986年   36344篇
  1985年   35176篇
  1984年   27079篇
  1983年   22751篇
  1982年   14692篇
  1981年   13257篇
  1980年   12407篇
  1979年   23917篇
  1978年   17497篇
  1977年   14755篇
  1976年   13541篇
  1975年   13994篇
  1974年   16359篇
  1973年   15626篇
  1972年   14321篇
  1971年   13169篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
91.
92.
Successful efforts in improving breastfeeding initiation rates at an urban teaching hospital prompted the hospital to create a lactation consultant (LC) position in the outpatient setting to focus on breastfeeding duration. This article reviews the complexity of the clinic setting, with the challenges and benefits of the consultant's first year in one of the hospital's outpatient clinics. Preliminary data collected by the consultant suggest that patients counseled by the LC in the outpatient clinic setting have longer breastfeeding duration rates.  相似文献   
93.
OBJECTIVE: To compare infants' discomfort, nursing-time and caregiver preference, and assess the clinical efficiency (as a secondary outcome) of hood versus facemask nebulization in infants with evolving bronchopulmonary dysplasia (BPD) in the neonatal intensive care unit. STUDY DESIGN: A prospective, open, randomized, controlled crossover clinical trial. In total, 10 infants with BPD who were on inhaled beta-agonist bronchodilators and corticosteroids were randomly assigned to receive their nebulized treatments either by a facemask, or by a hood for 2-3 days, and then crossover to receive the same treatments with the other technique for another 2-3 days. Infants' discomfort, nursing-time, caregiver preference and clinical efficiency were compared. RESULTS: At baseline there was no significant clinical difference between the groups. Nurse-time required for administering the hood nebulization (mean+/-s.e.m.: 1.9+/-0.1 min) was significantly shorter than the time for mask nebulization (12.0+/-0.6 min, P<0.0001). Infants' discomfort score was significantly lower (0.1+/-0.04) for hood versus mask nebulization (2.5+/-0.2, P<0.0001). Nurses and parents unequivocally preferred the hood treatment. During both mask and hood nebulization therapies (2-3 days) clinical efficiency was comparable. While both methods caused an immediate (20 min post) clinical improvement, the immediate respiratory assessment change score was significantly greater for the hood versus the mask nebulization (0.62+/-0.27 versus 0.13+/-0.14, P<0.05). CONCLUSIONS: Nebulization of aerosolized medications in infants with evolving BPD by hood was less time-consuming for caregivers and was much better tolerated by the infants while being at least as effective as the conventional facemask nebulization.  相似文献   
94.
BACKGROUND: 1Alpha,25-dihydroxyvitamin D(3) [1,25(OH)(2) Vitamin D(3)] induces growth inhibition in squamous cell carcinoma (SCC) cell lines of the head and neck by arresting the cells in the G0/G1 phase of the cell cycle, probably due to an enhanced expression of p21, which could be demonstrated in other cell lines (JPPA, SCC9) before. In SCC25, a SCC cell line isolated from tongue, growth inhibition but no overexpression of p21 was detected. The retinoblastoma gene, as a direct target of G1 cyclin-CDK complexes, showed an obvious shift from the hyperphosphorylated to the hypophosphorylated form under 1,25(OH)(2)Vitamin D(3), which indicates that the growth inhibition takes place in the G0/G1 phase. To explore the possible pathway of growth inhibition in SCC25 we investigated other cell cycle inhibitors (p18, p19, p27). METHODS: Synchronized cells were treated with 1,25(OH)(2)Vitamin D(3) over 96 h. The cell cycle status and expression of cell cycle-regulating proteins was determined by fluorescence-activated cell sorting (FACS) and Western blotting. An overexpression of p18 in 1,25(OH)(2)Vitamin D(3) vs. ethanol-treated cells was determined until 30 h in SCC25. No influence was detectable on the expression of p27 and p19. CONCLUSION: One mechanism by which 1,25(OH)(2)Vitamin D(3) controls cell growth might be the upregulation of p21. As p21 was unsusceptible to 1,25(OH)(2)Vitamin D(3) in SCC25, other inhibiting proteins were necessary to be tested. The proven upregulation of p18 seems to be the responsible step for growth inhibition of 1,25(OH)(2)Vitamin D(3) in SCC25.  相似文献   
95.
96.
97.
98.
99.
100.
S Raam  D M Vrabel 《Clinical chemistry》1988,34(10):2053-2057
We present evidence to show that monoclonal antibodies to estrogen receptors (ER) in solid phase recognize the secondary estrogen binding sites with moderate to low affinity for estradiol (E2). An excellent quantitative agreement was found in five cytosols between the ER values obtained by the enzyme immunoassay (ER-EIA) and the amount of secondary estrogen binding sites measured by the assay involving dextran-coated charcoal (Clin Chem 1986;32:1496). The immunoreactive protein recognized by the antibody-coated beads, when allowed to react with ER(+) cytosols, is shown to bind [3H]estradiol only when the ligand concentration exceeds 8 nmol/L. Further biochemical and functional characterization of the immunoreactive protein is required to establish similarities/dissimilarities between this protein, high-affinity Type I ER sites, and the secondary sites such as Type II sites.  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