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   1555篇
  免费   65篇
  国内免费   32篇
耳鼻咽喉   27篇
儿科学   92篇
妇产科学   22篇
基础医学   131篇
口腔科学   27篇
临床医学   133篇
内科学   391篇
皮肤病学   108篇
神经病学   42篇
特种医学   241篇
外国民族医学   1篇
外科学   150篇
综合类   31篇
预防医学   95篇
眼科学   8篇
药学   66篇
中国医学   6篇
肿瘤学   81篇
  2019年   11篇
  2018年   10篇
  2017年   13篇
  2016年   19篇
  2015年   22篇
  2014年   29篇
  2013年   73篇
  2012年   26篇
  2011年   33篇
  2010年   53篇
  2009年   57篇
  2008年   29篇
  2007年   42篇
  2006年   37篇
  2005年   35篇
  2004年   22篇
  2003年   26篇
  2002年   33篇
  2001年   32篇
  2000年   23篇
  1999年   30篇
  1998年   85篇
  1997年   74篇
  1996年   79篇
  1995年   50篇
  1994年   63篇
  1993年   55篇
  1992年   25篇
  1991年   19篇
  1990年   31篇
  1989年   48篇
  1988年   52篇
  1987年   35篇
  1986年   32篇
  1985年   33篇
  1984年   31篇
  1983年   15篇
  1982年   21篇
  1981年   21篇
  1980年   14篇
  1979年   19篇
  1978年   14篇
  1977年   16篇
  1976年   18篇
  1975年   14篇
  1973年   16篇
  1972年   8篇
  1971年   9篇
  1970年   8篇
  1965年   8篇
排序方式: 共有1652条查询结果,搜索用时 15 毫秒
1.
2.
3.
OBJECTIVES: To compare the relative amounts of elastase (primary polymorphonuclear leucocyte granule constituent) and lactoferrin (secondary PMN granule constituent) in the gingival crevicular fluid (GCF) of healthy, gingivitis and periodontitis sites.
DESIGN: This cross-sectional study looked at the two GCF constituents in three categories of disease status within the same subject.
MATERIALS AND METHODS: Patients with chronic adult periodontitis were screened and those exhibiting all three types of sites ie periodontally healthy, gingivitis and periodontitis sites were recruited (n = 10) and had GCF collected from the three sites. Lactoferrin and elastase were measured in eluates of GCF by enzyme-linked immunosorbent assay.
RESULTS: The absolute amount of lactoferrin measured in ng per 30 s samples was significantly lower in healthy and gingivitis sites as compared to periodontitis sites however this difference failed to reach significance when the concentration of lactoferrin in GCF was used as the analytical unit. No significant differences were found for elastase levels at any sites when expressed as either absolute amounts or concentrations. Secondary granule release, as evidenced by lactoferrin levels, occurs during cell migration and the process is independent of primary granule release, which is thought to correlate with PMN activation. The relationship between granule constituents in the samples showed significant differences, the highest lactoferrinlelastase ratio being at periodontitis sites (P < 0.001).
CONCLUSIONS These findings imply a change in the relative amounts of elastase and lactoferrin released at different disease level sites, with an almost 10-fold increase in the proportion of lactoferrin to elastase in periodontitis sites over healthy and gingivitis sites. This variation in the release by PMNs of primary and secondary granule constituents may indicate alterations in PMN function in different disease environments.  相似文献   
4.
We present an unusual case of haematogenous osteomyelitis in the diaphysis of the tibia of an adult leading to a subacute presentation with an extracortical abscess. Fluid from the abscess grew methicillin resistant Staphylococcus aureus (MRSA) on culture; MRSA with the same antibiogram had been grown from the patient’s blood seven years earlier following a bowel resection. Drainage of the abscess and curettage of the bone lesion together with appropriate antibiotic therapy led to resolution of the osteomyelitis.  相似文献   
5.
6.
Parent‐of‐origin–dependent (epi)genetic factors are important determinants of prenatal development that program adult phenotype. However, data on magnitude and specificity of maternal and paternal genome effects on fetal bone are lacking. We used an outbred bovine model to dissect and quantify effects of parental genomes, fetal sex, and nongenetic maternal effects on the fetal skeleton and analyzed phenotypic and molecular relationships between fetal muscle and bone. Analysis of 51 bone morphometric and weight parameters from 72 fetuses recovered at day 153 gestation (54% term) identified six principal components (PC1–6) that explained 80% of the variation in skeletal parameters. Parental genomes accounted for most of the variation in bone wet weight (PC1, 72.1%), limb ossification (PC2, 99.8%), flat bone size (PC4, 99.7%), and axial skeletal growth (PC5, 96.9%). Limb length showed lesser effects of parental genomes (PC3, 40.8%) and a significant nongenetic maternal effect (gestational weight gain, 29%). Fetal sex affected bone wet weight (PC1, p < 0.0001) and limb length (PC3, p < 0.05). Partitioning of variation explained by parental genomes revealed strong maternal genome effects on bone wet weight (74.1%, p < 0.0001) and axial skeletal growth (93.5%, p < 0.001), whereas paternal genome controlled limb ossification (95.1%, p < 0.0001). Histomorphometric data revealed strong maternal genome effects on growth plate height (98.6%, p < 0.0001) and trabecular thickness (85.5%, p < 0.0001) in distal femur. Parental genome effects on fetal bone were mirrored by maternal genome effects on fetal serum 25‐hydroxyvitamin D (96.9%, p < 0.001) and paternal genome effects on alkaline phosphatase (90.0%, p < 0.001) and their correlations with maternally controlled bone wet weight and paternally controlled limb ossification, respectively. Bone wet weight and flat bone size correlated positively with muscle weight (r = 0.84 and 0.77, p < 0.0001) and negatively with muscle H19 expression (r = –0.34 and –0.31, p < 0.01). Because imprinted maternally expressed H19 regulates growth factors by miRNA interference, this suggests muscle‐bone interaction via epigenetic factors. © 2014 American Society for Bone and Mineral Research.  相似文献   
7.
To ensure their high proliferation rate, tumor cells have an iron metabolic disorder causing them to have increased iron needs, making them more susceptible to iron deprivation. This vulnerability could be a therapeutic target. In breast cancers, the development of new therapeutic approaches is urgently needed for patients with triple‐negative tumors, which frequently relapse after chemotherapy and suffer from a lack of targeted therapies. In this study, we demonstrated that deferasirox (DFX) synergises with standard chemotherapeutic agents such as doxorubicin, cisplatin and carboplatin to inhibit cell proliferation and induce apoptosis and autophagy in triple‐negative breast cancer (TNBC) cells. Moreover, the combination of DFX with doxorubicin and cyclophosphamide delayed recurrences in breast cancer patient‐derived xenografts without increasing the side‐effects of chemotherapies alone or altering the global iron storage of mice. Antitumor synergy of DFX and doxorubicin seems to involve downregulation of the phosphoinositide 3‐kinase and nuclear factor‐κB pathways. Iron deprivation in combination with chemotherapy could thus help to improve the effectiveness of chemotherapy in TNBC patients without increasing toxicity. Copyright © 2018 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.  相似文献   
8.
9.

Background

Early environmental exposures may help shape the development of the autonomic nervous system (ANS) and hypothalamic–pituitary–adrenal (HPA) axis, influencing vulnerability for health problems across the lifespan. Little is known about the role of maternal sensitivity in influencing the development of the ANS in early life.

Aims

To examine associations among maternal sensitivity and infant behavioral distress and ANS and HPA axis reactivity to the Repeated Still-Face Paradigm (SFP-R), a dyadic stress task.

Study design

Observational repeated measures study.

Subjects

Thirty-five urban, sociodemographically diverse mothers and their 6-month-old infants.

Outcome measures

Changes in infant affective distress, heart rate, respiratory sinus arrhythmia (RSA), and T-wave amplitude (TWA) across episodes of the SFP-R were assessed. A measure of cortisol output (area under the curve) in the hour following cessation of the SFP-R was also obtained.

Results

Greater maternal insensitivity was associated with greater infant sympathetic activation (TWA) during periods of stress and tended to be associated with greater cortisol output following the SFP-R. There was also evidence for greater affective distress and less parasympathetic activation (RSA) during the SFP-R among infants of predominantly insensitive mothers.

Conclusions

Caregiving quality in early life may influence the responsiveness of the sympathetic and parasympathetic branches of the ANS as well as the HPA axis. Consideration of the ANS and HPA axis systems together provides a fuller representation of adaptive versus maladaptive stress responses. The findings highlight the importance of supporting high quality caregiving in the early years of life, which is likely to promote later health.  相似文献   
10.
目的:虽然前交叉韧带的重建手术已趋成熟,但重建术后韧带稳定性的量化评估仍缺乏一种有效的方法。探讨KT1000/KT2000关节测量仪在膝关节前交叉韧带损伤中的诊断价值以及在韧带重建术后移植物稳定性评估中的应用价值。方法:选择2006-01/2007-01于上海交通大学附属第六人民医院行关节镜下重建手术的膝关节前交叉韧带完全损伤患者80例,对治疗方案均知情同意。①术前利用KT1000/KT2000关节测量仪进行膝关节稳定性的测量,并与抽屉试验、Lachman试验、轴移试验及MRI影像学等检查方法进行对比,验证其敏感度。②分别在术后3个月、6个月、1年以及1年以上利用KT1000/KT2000关节测量仪进行随访测量,采用国际膝关节文献委员会评分对测量结果进行前交叉韧带的稳定性评估,评估标准:等级A为韧带紧张度良好;等级B为韧带紧张度接近正常;等级C为韧带紧张度异常;等级D为韧带紧张度严重异常。结果:80例前交叉韧带完全损伤患者全部进入结果分析。①KT1000测量仪在诊断前交叉韧带损伤时较前抽屉试验及轴移试验敏感率高(P=0.001,0.037),而与Lachman试验及MRI影像学检查敏感率差异无显著性意义(P=0.807,0.598)。②随访结果:术后3个月随访到80例患者,A级68例,B级12例;术后6个月随访到76例患者,A级55例,B级19例,C级1例;术后1年随访到70例患者,A级48例,B级20例;C级2例;术后1年以上随访到68例患者,A级42例,B级22例,C级4例。结论:KT1000/KT2000关节测量仪测量膝关节稳定性的敏感度较高,不仅可应用于膝关节前交叉韧带损伤的临床诊断,还可以评价手术效果,对前交叉韧带重建术后评估移植物稳定性提供了一个量化依据。  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