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   879篇
  免费   53篇
  国内免费   26篇
耳鼻咽喉   7篇
儿科学   58篇
妇产科学   9篇
基础医学   105篇
口腔科学   24篇
临床医学   90篇
内科学   195篇
皮肤病学   7篇
神经病学   48篇
特种医学   130篇
外科学   83篇
综合类   8篇
预防医学   43篇
眼科学   6篇
药学   93篇
中国医学   3篇
肿瘤学   49篇
  2022年   6篇
  2021年   10篇
  2020年   4篇
  2019年   8篇
  2018年   13篇
  2017年   9篇
  2016年   15篇
  2015年   19篇
  2014年   17篇
  2013年   25篇
  2012年   26篇
  2011年   27篇
  2010年   19篇
  2009年   29篇
  2008年   28篇
  2007年   50篇
  2006年   23篇
  2005年   33篇
  2004年   23篇
  2003年   24篇
  2002年   17篇
  2001年   25篇
  2000年   22篇
  1999年   18篇
  1998年   41篇
  1997年   50篇
  1996年   55篇
  1995年   41篇
  1994年   32篇
  1993年   32篇
  1992年   17篇
  1991年   14篇
  1990年   14篇
  1989年   23篇
  1988年   21篇
  1987年   13篇
  1986年   13篇
  1985年   13篇
  1984年   12篇
  1983年   7篇
  1982年   7篇
  1981年   6篇
  1980年   7篇
  1979年   5篇
  1978年   3篇
  1977年   7篇
  1976年   8篇
  1975年   11篇
  1972年   2篇
  1971年   2篇
排序方式: 共有958条查询结果,搜索用时 15 毫秒
71.
OBJECTIVE: The purpose of this study was to assess the clinical and economic impact of the introduction of inhaled corticosteroid therapy for asthma in a cohort of children 12 years and younger who were North Carolina Medicaid enrollees.
METHODS: The North Carolina Medicaid claims database was used to retrieve clinical and economic variables for the purpose of this study. The case group, which was comprised of 84 children who started corticosteroid inhaler therapy between March 1994 and March 1995, was followed up for 1 year before and 1 year after the start of the therapy. The control group was comprised of 72 children with similar severity of asthma who remained on any other therapy other than corticosteroids for a continuous 2-year period. Paired t-tests were used to compare differences, and multiple regression analysis was used to adjust for potential confounders.
RESULTS: There was a 58% reduction in hospital visits, and a 19% reduction in physician visits in the case group after initiation of inhaled corticosteroids. In the control group, an increase of 34% in the number of outpatient visits occurred in the second year. All the decreases and increases were statistically significant. Children with regular patterns of inhaled corticosteroid refills were found to be significantly lower costing for Medicaid. However, after adjusting for potential confounders, no significant change in health care costs per asthmatic child occurred as a result of the introduction of inhaled corticosteroid therapy.
CONCLUSION: Overall, the study found that introduction of inhaled corticosteroids in a cohort of asthmatic children enrolled in Medicaid was beneficial to Medicaid because it brought about dramatic decreases in health care utilization without additionally increasing costs.  相似文献   
72.
Information on parental asthma management practices for young children is sparse. The objective of this article is to determine if specific caregiver asthma management practices for children were associated with children's asthma morbidity. Caregivers of 100 inner-city children diagnosed with persistent asthma and participating in an ongoing asthma intervention study were enrolled and interviewed to ascertain measures of asthma morbidity, medication use, health care use (acute and primary care), and asthma management practices. Overall, asthma morbidity was high with almost two thirds of caregivers reporting their child having one or more emergency department visits within the last 6 months and 63% receiving specialty care for their asthma. Appropriate medication use was reported predominantly as albuterol and inhaled steroids (78%). However, only 42% of caregivers reported administering asthma medicines when their child starts to cough and less than half (39%) reported having an asthma action plan. There were no significant differences by asthma severity level for any asthma management practice. In conclusion, caregivers lack knowledge regarding cough as an early asthma symptom. Caregivers should be encouraged to review asthma action plans with health care providers at each medical encounter.  相似文献   
73.
鼓槌石斛化学成分的研究   总被引:11,自引:0,他引:11  
自中药鼓槌石斛(Dendrobium chrysotoxum Lindl.)茎中分离到5个化合物,经光谱(UV,IR,MS,1HNMR,DIFNOE和13CNMR)分析,分别鉴定为β-谷甾醇(I)、鼓槌菲(chrysotoxene,II)、毛兰素(erianin,III)、毛兰菲(confusarin,IV)和鼓槌联苄(chrysotobibenzyl,V)。II是新化合物,V是新天然产物。  相似文献   
74.
刺蒺藜果中一种新桂皮酰胺类成分的分离和鉴定   总被引:5,自引:0,他引:5  
从刺蒺藜(Tribulus terrestris L)果实中分得两个化合物,经理化常数测定和光谱(UV,IR,1HNMR,13CNMR,1H-13CCOSY和MS)解析。化合物I鉴定为N-对羟基苯乙酮基-3-甲氧基-4-羟基取代桂皮酰胺,为一新化合物,命名为蒺藜酰胺(terrestriamide)。化合物II为8-甲基氢化茚酮-1,首次从该植物中获得。  相似文献   
75.
海南粗榧新碱衍生物HH07A对体外L1210细胞的杀伤作用   总被引:1,自引:0,他引:1  
体外培养的小鼠L1210细胞被HH07A2μg·ml-1作用24h后,与对照组细胞相比,其细胞数不再增长,有丝分裂数及集落形成率下降,细胞形态及细胞周期动力学均发生一定的变化。且HH07A大剂量短期作用抑制Ll210细胞集落形成的效率高于低剂量持续作用。  相似文献   
76.

Background  

Continuous intrathecal drug delivery has been shown in open studies to improve pain and quality of life in those with intractable back pain who have had spinal surgery. There is limited data on long term effects and and even less for patients with mechanical back pain without prior spinal surgery.  相似文献   
77.
Efficacy study of the small-bowel examination   总被引:8,自引:0,他引:8  
  相似文献   
78.
79.
Blood coagulation is initiated when plasma factor VII(a) binds to its essential cofactor tissue factor (TF) and proteolytically activates factors X and IX. Progressive inhibition of TF activity occurs upon its addition to plasma. This process is reversible and requires the presence of VII(a), catalytically active Xa, Ca2+, and another component that appears to be associated with the lipoproteins in plasma, a lipoprotein-associated coagulation inhibitor (LACI). A protein, LACI(HG2), possessing the same inhibitory properties as LACI, has recently been isolated from the conditioned media of cultured human liver cells (HepG2). Rabbit antisera raised against a synthetic peptide based on the N-terminal sequence of LACI(HG2) and purified IgG from a rabbit immunized with intact LACI(HG2) inhibit the LACI activity in human serum. In a reaction mixture containing VIIa, Xa, Ca2+, and purified LACI(HG2), the apparent half-life (t1/2) for TF activity was 20 seconds. The presence of heparin accelerated the initial rate of inhibition threefold. Antithrombin III alpha alone had no effect, but antithrombin III alpha with heparin abrogated the TF inhibition. LACI(HG2) also inhibited Xa with an apparent t1/2 of 50 seconds. Heparin enhanced the rate of Xa inhibition 2.5-fold, whereas phospholipids and Ca2+ slowed the reaction 2.5-fold. Xa inhibition was demonstrable with both chromogenic substrate (S-2222) and bioassays, but no complex between Xa and LACI(HG2) could be visualized by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Nondenaturing PAGE, however, showed that LACI(HG2) bound to Xa but not to X or Xa inactivated by diisopropyl fluorophosphate. Thus, LACI(HG2) appears to bind to Xa at or near its active site. Bovine factor Xa lacking its gamma-carboxyglutamic acid-containing domain, BXa(-GD), through treatment with alpha-chymotrypsin, was used to further investigate the Xa requirement for VIIa/TF inhibition by LACI(HG2). LACI(HG2) bound to BXa(-GD) and inhibited its catalytic activity against a small molecular substrate (Spectrozyme Xa), though at a rate approximately sevenfold slower than native BXa. Preincubation of LACI(HG2) with saturating concentrations of BXa(-GD) markedly retarded the subsequent inhibition of BXa. The VII(a)/TF complex was not inhibited by LACI(HG2) in the presence of BXa(-GD), and further, preincubation of LACI(HG2) with BXa(-GD) slowed the inhibition of VIIa/TF after the addition of native Xa. The results are consistent with the hypothesis that inhibition of VII(a)/TF involves the formation of a VIIa-TF-XA-LACI complex that requires the GD of XA.(ABSTRACT TRUNCATED AT 400 WORDS)  相似文献   
80.
Clonal rearrangements of the Ig heavy chain (IGH) locus occur in nearly all cases of B-cell precursor acute leukemia (BCP-ALL). Some of these rearrangements may be detected by polymerase chain reaction (PCR) using VH gene framework III (FRIII) and JH consensus primers. However, about 20% of BCP-ALLs fail to amplify with this technique. To determine the causes of these PCR failures and to investigate any possible association with specific subgroups of disease, we analyzed 72 acute leukemias of defined immunophenotype and cytogenetics, comparing FRIII with VH-family leader-specific PCR methods and Southern blotting. Of 37 BCP-ALL cases, 6 (16.2%) failed totally to amplify with FRIII and JH primers. None of these cases amplified with VH leader primers. Additionally, all cases retained germline VH6 genes and 5 of 11 rearranged alleles amplified with a consensus DH primer, indicating that these rearrangements represented biallelic DH-JH recombinations. Among the 6 FRIII and VH leader PCR-negative BCP-ALL cases, there was no common immunophenotype or consistent cytogenetic abnormality, although all showed structural chromosomal abnormalities and 3 of 5 successfully karyotyped had abnormalities of chromosome 12p. 13 cases with t(9;22)(q34;q11) Philadelphia chromosome-positive [Ph+]) and IGH rearrangements (9 BCP-ALL and 4 biphenotypic cases) were also analyzed. Of 23 rearranged IGH alleles, 19 (82%) were positive by FRIII PCR, and all 4 remaining alleles were amplified by VH leader primers. Use of the leader primers in these Ph+ cases also detected 3 additional clonal rearrangements that were not anticipated from Southern blotting; such unexpected bands were not observed in 21 other Ph- cases. The additional bands represented "new" and unrelated VH rearrangements rather than VH-VH replacement events. We conclude that biallelic DHJH rearrangements occur in a subgroup of BCP-ALL; in these cases, the activation of the full VHDHJH recombination mechanism had not occurred. Therefore, these cases of BCP-ALL were arrested at an early stage of B- cell differentiation. In contrast, all Ph+ BCP-ALLs and biphenotypic acute leukemias, which may represent the transformation of multipotent hemopoietic stem cells, had undergone VHDHJH recombination. Of 9 Ph+ BCP-ALL cases, 3 also showed ongoing VHDHJH rearrangement, reflecting the persistent expression of the VHDHJH recombinase. Finally, sequence analysis of 33 rearranged VHDHJH genes showed that only 3 including 2 Ph+ BCP-ALL maintained an intact open-reading frame. Loss of the open- reading frame occurred not only because of out-of-frame VHDH and DHJH joining, but also because of VH gene mutation and deletion. These data show that most BCP-ALLs may represent the neoplastic transformation of BCPs destined to die in the bone marrow.  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