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   4999篇
  免费   256篇
  国内免费   198篇
耳鼻咽喉   35篇
儿科学   59篇
妇产科学   37篇
基础医学   523篇
口腔科学   204篇
临床医学   288篇
内科学   335篇
皮肤病学   203篇
神经病学   373篇
特种医学   103篇
外科学   285篇
综合类   640篇
预防医学   436篇
眼科学   81篇
药学   1559篇
  2篇
中国医学   212篇
肿瘤学   78篇
  2023年   27篇
  2022年   45篇
  2021年   111篇
  2020年   91篇
  2019年   94篇
  2018年   78篇
  2017年   99篇
  2016年   137篇
  2015年   134篇
  2014年   239篇
  2013年   307篇
  2012年   253篇
  2011年   327篇
  2010年   226篇
  2009年   217篇
  2008年   250篇
  2007年   253篇
  2006年   212篇
  2005年   197篇
  2004年   195篇
  2003年   167篇
  2002年   134篇
  2001年   99篇
  2000年   97篇
  1999年   96篇
  1998年   82篇
  1997年   96篇
  1996年   89篇
  1995年   84篇
  1994年   93篇
  1993年   85篇
  1992年   58篇
  1991年   56篇
  1990年   74篇
  1989年   70篇
  1988年   51篇
  1987年   42篇
  1986年   41篇
  1985年   66篇
  1984年   55篇
  1983年   47篇
  1982年   41篇
  1981年   48篇
  1980年   39篇
  1979年   24篇
  1978年   29篇
  1977年   19篇
  1976年   26篇
  1975年   17篇
  1974年   13篇
排序方式: 共有5453条查询结果,搜索用时 15 毫秒
1.
BackgroundCalcium chloride is commonly used in emergency departments in the treatment of a variety of emergencies. Historically, administration via central venous catheters has been preferred owing to its high osmolarity and vesicant properties. Although preferred, central access may not always be available in time-sensitive, emergent situations leading to many instances of peripheral administration. The objective of this analysis was to evaluate the charted safety of peripheral venous administration of 10% calcium chloride.MethodsA single-center retrospective chart review was performed in patients who received 10% calcium chloride in the adult emergency department evaluating for the incidence of infusion-related adverse events. Patients were excluded if they were less than 18 years of age or had a lack of catheter documentation during 10% calcium chloride administration or if the 10% calcium chloride was documented as given through a central venous catheter.ResultsA total of 72 administrations were evaluated. Patients were predominantly male (67%), with a median age of 55 years and body mass index of 29.2. The primary outcome demonstrated that 4 infusion-related adverse events occurred (6%) with grade 1 (n = 1) and grade 0 (n = 3) documented incidence of infusion-related adverse events. None of the documented incidence of infusion-related adverse events resulted in permanent tissue injury, and all patients had conservative management.DiscussionThis study demonstrated that administration of 10% calcium chloride via peripheral venous catheters may be feasible and seemed to carry a low incidence of documented complications. Further prospective studies are needed to confirm study observations.  相似文献   
2.
ObjectiveCalcium-activated chloride channel 2 (CLCA2) is closely related to the invasion, metastasis, and prognosis of some common malignant tumors. The present study aimed to evaluate the role of CLCA2 in cervical squamous cell carcinoma (CESC) using bioinformatics analysis.Materials and methodsThe mRNA sequencing data and the corresponding clinical data were obtained from Gene Expression Omnibus (GEO) database and The Cancer Genome Atlas (TCGA) database respectively. Then univariate analysis of variance was used to analyze the differential mRNA expression of CLCA2 between normal, cervical Intraepithelial neoplasia (CIN), and CESC tissues and clinicopathological characteristics. The Gene Expression Profiling Interactive Analysis (GEPIA) was used to assess the association between CLCA2 and Disease-Free Survival (DFS), overall survival (OS). The Gene Set Enrichment Analysis (GSEA) was used to explore the associated signaling pathways. The Tumor Immune Estimation Resource (TIMER) was used to predict the potential biological roles of CLCA2 in tumor-immune of CESC.ResultsCLCA2 expression was significantly decreased in CESC tissues compared with normal and CIN tissues (P < 0.05). Meanwhile, obese patients had lower levels of CLCA2 expression than normal-weight CESC patients (P < 0.05). However, there was no significant difference in the expression level of CLCA2 in patients with different T stage, lymph node status, metastasis, and FIGO stage in CC(P > 0.05). The survival analysis indicated that for DFS, CESC with high CLCA2 expression was associated with better prognoses compared with those with low expression levels (P < 0.05). But for the OS, there was no difference. GSEA revealed that 4 pathways exhibited significant differential enrichment in the CLCA2 high-expression phenotype, including the P53 signaling pathway, the ERBB signaling pathway, the NOTCH signaling pathway, and the ubiquitin-mediated proteolysis. The TIMER reveals the expression of CLCA2 showed a significant inverse association with the number of B cells, Macrophage cells, and Dendritic Cell infiltration.ConclusionThe present study indicates that CLCA2 expression may be a potential prognostic marker for patients with CESC.  相似文献   
3.
4.
The number of reinforced concrete structures subject to anoxic conditions such as offshore platforms and geological storage facilities is growing steadily. This study explored the behaviour of embedded steel reinforcement corrosion under anoxic conditions in the presence of different chloride concentrations. Corrosion rate values were obtained by three electrochemical techniques: Linear polarization resistance, electrochemical impedance spectroscopy, and chronopotenciometry. The corrosion rate ceiling observed was 0.98 µA/cm2, irrespective of the chloride content in the concrete. By means of an Evans diagram, it was possible to estimate the value of the cathodic Tafel constant (bc) to be 180 mV dec−1, and the current limit yielded an ilim value of 0.98 µA/cm2. On the other hand, the corrosion potential would lie most likely in the −900 mVAg/AgCl to −1000 mVAg/AgCl range, whilst the bounds for the most probable corrosion rate were 0.61 µA/cm2 to 0.22 µA/cm2. The experiments conducted revealed clear evidence of corrosion-induced pitting that will be assessed in subsequent research.  相似文献   
5.
目的 研究含2%氯化锶的脱敏剂对牙本质小管的封堵效果,并对其生物安全性进行评价。方法 制备含2%十二烷基硫酸钠( SLS)和2%氯化锶的脱敏糊剂( DS1)。选择无龋坏无缺陷的牛下颌切牙制备牙本质片24个,随机分3组,分别置于DS1(实验组)、普通含氟牙膏(阴性对照组)和去离子水(空白对照组)中进行刷牙处理。牛牙表面连续处理7天后采用扫描电子显微镜( SEM)及其图像分析研究含锶脱敏糊剂对牙本质小管的封堵率。另外,选择市售含氟牙膏(阴性对照)、不含SLS的脱敏糊剂( DS2)及3种同类脱敏产品,采用滤膜扩散法进行体外细胞毒性研究,并评价脱敏糊剂DS1浸提液的口腔黏膜刺激反应和皮肤致敏反应。采用一次限量法研究脱敏糊剂的急性经口毒性( LD50)。结果 SEM分析表明,DS1对牙本质小管的封堵率为70.97%,阴性对照组为48.29%,两者之间及相比空白对照组,差异均具有统计学意义( P < 0.05)。DS1具有一定的细胞毒性,但未产生刺激和致敏反应。DS1的LD50大于5 000 mg/kg,但呈现实际无毒的结果。结论 在本研究中,含有2%的SLS和2%的SrCl2 · 6H2O的脱敏糊剂具有良好的生物安全性,对牙本质小管的封堵效果较好。  相似文献   
6.
Cadmium is known as an oxidative stress‐inducing factor. Silymarin extracted from Silybum marianum is regarded as a potent antioxidant. The present study investigated the preventing effects of silymarin on cadmium chloride‐induced toxicity in terms of testis histopathology and serum testosterone level as well as oxidative stress indicators in mice. In addition, the activities of antioxidant defence enzymes was evaluated. Adult male mice were divided into four groups (n = 6 in each group): (a) control; (b) cadmium chloride; (c) silymarin + cadmium chloride and (d) Silymarin. In this study, cadmium chloride significantly decreased the diameter and wall thickness of the seminiferous tubule, diameter of the spermatogonia nucleus and serum testosterone levels compared to the control group. Furthermore, in mice treated with this pollutant, a significant increase in malondialdehyde was observed while ferric reducing antioxidant power level, and the activity of catalase, superoxide dismutase and glutathione peroxidase were significantly reduced in the testis. In the silymarin + cadmium chloride group, silymarin could significantly reverse the toxic effects of cadmium chloride. The findings of this study showed that silymarin, as a potent antioxidant, can compensate the adverse effects of cadmium chloride on testis histopathology, testosterone level, oxidative stress indicators and antioxidant defence enzymes in mice.  相似文献   
7.
《Dental materials》2019,35(6):e113-e121
ObjectiveTo compare the retention force of individual clasps made from cobalt chromium (CoCr) or new aryl ketone polymer (AKP) material, Ultaire™ AKP, following prolonged fatigue testing along ideal and non-ideal paths of removal and to assess 3D deformation of the active and passive clasp tips.MethodsCoCr and AKP clasps were manufactured in their standard, respective processes, digitally scanned prior to testing, then cycled 15,000 times over an e.max analogue crown in artificial saliva. Retentive load was measured in situ, as a function of cycles. Clasps were rescanned to assess deformation and along with their antagonists subjected to SEM to assess localised wear.ResultsDistortion of the CoCr clasps was consistently larger than Ultaire™ AKP clasps, irrespective of removal path. CoCr clasps had significantly higher retentive forces than AKP clasps, for both removal paths. Ultaire™ AKP clasps showed a lower but relatively constant retentive force. The non-ideal path of removal affected retentive forces for both clasp materials. SEM showed localised removal of glaze for e.max crowns used with CoCr clasps.SignificanceUltaire™ AKP clasps showed significantly less permanent deformation and lower retentive force than CoCr clasps. Unlike CoCr, the Ultaire™ AKP clasps did not work harden, nor had as large a reduction in retentive force and accompanying permanent deformation; the retentive force for the Ultaire™ AKP clasps was consistent over 15,000 cycles of fatigue mimicking prolonged clinical use. The AKP material was more robust; showing minimal deformation even in non-ideal paths of removal, as many patients would routinely use.  相似文献   
8.
9.
A high salt diet (HSD) is among the most important risk factors for many diseases. One mechanism by which HSD aggravates cerebral ischemic injury is independent of blood pressure changes. The direct role of HSD in inflammation after cerebral ischemia is unclear. In this research, after twenty-one days of being fed a high salt diet, permanent focal ischemia was induced in mice via operation. At 12 h and 1, 3 and 5 days postischemia, the effects of HSD on the lesion volume, microglia polarization, aldose reductase (AR) expression, and inflammatory processes were analyzed. We report that in mice, surplus dietary salt promotes inflammation and increases the activation of classical lipopolysaccharide (LPS)-induced microglia/macrophages (M1). This effect depends on the expression of the AR protein in activated microglia after permanent middle cerebral artery ligation (pMCAL) in HSD mice. The administration of either the AR inhibitor Epalrestat or a p38-neutralizing antibody blocked the polarization of microglia and alleviated stroke injury.In conclusion, HSD promotes polarization in pro-inflammatory M1 microglia by upregulating the expression of the AR protein via p38/MAPK, thereby exacerbating the development of ischemia stroke.  相似文献   
10.
目的 探讨阻断脑源性神经营养因子(BDNF)-酪氨酸激酶受体B(TrkB)通路后运动训练对脊髓损伤(SCI)大鼠痉挛状态及钾-氯协同转运蛋白2(KCC2)表达的影响。 方法 将40只雌性 SD大鼠按随机数字表法分为假手术组(Sham组)、SCI+磷酸盐缓冲液组(SCI/PBS组)、SCI-运动训练+PBS组(SCI-TT/PBS组)、SCI/TrkB-IgG组和SCI-TT/TrkB-IgG组。于SCI前1周对所有大鼠进行鞘内置管,置管1周后制作T10不完全SCI大鼠模型,Sham组仅暴露脊髓。于SCI制模术后第 7天,使用TrkB-IgG阻断SCI/TrkB-IgG和SCI-TT/TrkB-IgG组的BDNF-TrkB信号通路,其余三组使用PBS进行对照。SCI后第8天,SCI-TT/PBS组和 SCI-TT/TrkB-IgG组进行4周的减重平板训练。使用Asworth评定法和H反射(H-max/M-max比值)评估大鼠后肢的痉挛状态。实验结束后采用 Western Blot和免疫组化技术检测各组大鼠损伤远段脊髓 KCC2的表达情况。 结果 SCI后1~5周,4组SCI大鼠的Ashworth痉挛分级均较Sham组增加。SCI后3~5周,SCI-TT/PBS组Ashworth痉挛分级明显小于SCI/PBS组和SCI/TrkB-IgG组(P<0.05);SCI后第5周,SCI-TT/PBS组Ashworth痉挛分级小于SCI-TT/TrkB-IgG组(P<0.05);SCI后1~5周,Sham组H-max/M-max比值保持不变,均低于4组SCI大鼠(P<0.05)。SCI后第1周和第2周,4组SCI大鼠H-max/M-max比值差异无统计学意义(P>0.05)。SCI后3~5周,SCI-TT/PBS组H-max/M-max比值明显低于SCI/PBS组、SCI/TrkB-IgG组和SCI-TT/TrkB-IgG组(P<0.05)。SCI后4~5周,SCI-TT/TrkB-IgG组H-max/M-max比值明显低于SCI/TrkB-IgG组(P<0.05)。KCC2免疫组化及Western Blot结果显示,SCI 5周后,4组SCI大鼠的损伤远端脊髓前角KCC2的表达量较Sham组明显减少(P<0.05)。运动训练可明显增加SCI-TT/PBS组KCC2的表达量,其免疫强度和相对光密度值均高于SCI/PBS组、SCI/TrkB-IgG组和SCI-TT/TrkB-IgG组(P<0.05)。而SCI/TrkB-IgG组与SCI-TT/TrkB-IgG组差异无统计学意义(P>0.05)。 结论 减重平板训练可通过BDNF-TrkB信号通路改善 SCI大鼠的痉挛状态并促进损伤远端脊髓内KCC2的表达。  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