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   10795篇
  免费   920篇
  国内免费   379篇
耳鼻咽喉   38篇
儿科学   191篇
妇产科学   97篇
基础医学   721篇
口腔科学   167篇
临床医学   801篇
内科学   918篇
皮肤病学   136篇
神经病学   378篇
特种医学   339篇
外国民族医学   1篇
外科学   595篇
综合类   1323篇
预防医学   933篇
眼科学   240篇
药学   4307篇
中国医学   737篇
肿瘤学   172篇
  2023年   164篇
  2022年   205篇
  2021年   369篇
  2020年   322篇
  2019年   324篇
  2018年   358篇
  2017年   309篇
  2016年   293篇
  2015年   260篇
  2014年   600篇
  2013年   643篇
  2012年   642篇
  2011年   748篇
  2010年   610篇
  2009年   506篇
  2008年   545篇
  2007年   583篇
  2006年   472篇
  2005年   433篇
  2004年   423篇
  2003年   348篇
  2002年   275篇
  2001年   213篇
  2000年   243篇
  1999年   188篇
  1998年   126篇
  1997年   171篇
  1996年   127篇
  1995年   143篇
  1994年   119篇
  1993年   105篇
  1992年   111篇
  1991年   97篇
  1990年   104篇
  1989年   66篇
  1988年   80篇
  1987年   51篇
  1986年   54篇
  1985年   85篇
  1984年   81篇
  1983年   49篇
  1982年   76篇
  1981年   61篇
  1980年   59篇
  1979年   61篇
  1978年   33篇
  1977年   49篇
  1976年   30篇
  1975年   22篇
  1974年   18篇
排序方式: 共有10000条查询结果,搜索用时 250 毫秒
1.
目的 检测蒜氨酸最低抑菌浓度(MIC)与最低杀菌浓度(MBC),探讨蒜氨酸体内外抗菌机制。方法 体外微量稀释法检测蒜氨酸MIC和MBC,荧光显微镜观察菌体表面蒜氨酸,探讨蒜氨酸抗菌机制。体内蒜氨酸和青霉素分别治疗金葡菌感染家兔脓肿,检测脓汁标本中细菌存活情况,探讨体内蒜氨酸抗菌作用。结果 蒜氨酸对大肠杆菌、伤寒杆菌、金黄色葡萄球菌、白色葡萄球菌的MIC分别为3.047 μg·mL-1、6.094 μg·mL-1、0.386 μg·mL-1、0.386 μg·mL-1,蒜氨酸体外无杀菌活性。浓汁标本:死菌率蒜氨酸治疗组显著高于阴性对照组(P < 0.01),与青霉素治疗组无明显差异(P > 0.05);活菌率蒜氨酸治疗组显著低于阴性对照组(P < 0.01),与青霉素治疗组无明显差异(P > 0.05)。结论 蒜氨酸与菌体蛋白、细菌酶蛋白结合阻断细菌与环境物质交换,抑制细菌生命活动,具有较强的抑菌作用,无杀菌活性;蒜氨酸体内代谢成大蒜素,具有较强杀菌作用。  相似文献   
2.

Background

The purpose of this study was to compare the outcomes of trauma patients who were injured in a motor vehicle crash and tested positive for alcohol upon hospital arrival versus those who tested negative.

Methods

Study data came from the US National Trauma Data Bank (2007–2010). Any blood alcohol concentration (BAC) found at or above the legal limit (≥0.08?g/dL) was considered “alcohol positive”, and if no alcohol was identified through testing, the patient was considered “alcohol negative”. Patients’ demographics including age >?=?14, race, gender, drug test results, systolic blood pressure, heart rate, injury severity score (ISS), and Glasgow Coma Scale (GCS) were included in the study. Propensity score and exact pair matching were performed between the groups using baseline characteristics.

Results

From a total of 88,794 patients, 30.9% tested positive and 69.1% tested negative for alcohol. There were significant differences found between the groups regarding age, gender, race, and GCS (all p?<?0.001) as well as a significantly higher in-hospital mortality rate (3.5% vs. 2.7%, p?<?0.001) and median time to patient expiration (4 vs. 3 days, p?<?0.001) in the alcohol negative group. After running both matching scenarios, there was no evidence of a significant difference seen in the rates of in-hospital mortality or the median time to patient expiration between the alcohol groups in either matched comparison.

Conclusion

Patients who tested positive for alcohol following a traumatic motor vehicle crash showed no significant increase in in-hospital mortality or time to expiration when compared to propensity score and exact matched patients who tested negative for alcohol.  相似文献   
3.

Introduction

Physician communication impacts patient outcomes. However, communication skills, especially around difficult conversations, remain suboptimal, and there is no clear way to determine the validity of entrustment decisions. The aims of this study were to 1) describe the development of a simulation-based mastery learning (SBML) curriculum for breaking bad news (BBN) conversation skills and 2) set a defensible minimum passing standard (MPS) to ensure uniform skill acquisition among learners.

Innovation

An SBML BBN curriculum was developed for fourth-year medical students. An assessment tool was created to evaluate the acquisition of skills involved in a BBN conversation. Pilot testing was completed to confirm improvement in skill acquisition and set the MPS.

Outcomes

A BBN assessment tool containing a 15-item checklist and six scaled items was developed. Students' checklist performance improved significantly at post-test compared to baseline (mean 65.33%, SD = 12.09% vs mean 88.67%, SD = 9.45%, P < 0.001). Students were also significantly more likely to have at least a score of 4 (on a five-point scale) for the six scaled questions at post-test. The MPS was set at 80%, requiring a score of 12 items on the checklist and at least 4 of 5 for each scaled item. Using the MPS, 30% of students would require additional training after post-testing.

Comments

We developed a SBML curriculum with a comprehensive assessment of BBN skills and a defensible competency standard. Future efforts will expand the mastery model to larger cohorts and assess the impact of rigorous education on patient care outcomes.  相似文献   
4.
PurposeTo investigate dynamic variables obtained from retrospective computed tomography angiography for ability to predict thoracic endovascular aortic repair (TEVAR) outcomes in patients with complicated type B aortic dissection (cTBAD).Materials and MethodsSeventy-nine patients with cTBAD who received TEVAR from March 2009 to June 2018 were retrospectively enrolled. Relative true lumen area (r-TLA) was computed at the level of tracheal bifurcation every 5% of all R-R intervals. Parameters that reflect the state of intimal motion were evaluated, including difference between maximum and minimum r-TLA (D-TLA) and true lumen collapse. The endpoints comprised early (≤ 30 days) and late (> 30 days) outcomes after intervention.ResultsOverall early mortality rate was 13.9% (11/79), and early adverse events rate was 24.1% (19/79). Patients who received TEVAR within 2 days of symptom onset demonstrated the worst outcomes. A longer time of r-TLA < 25% in 1 cardiac cycle (P = .049) and larger D-TLA (P < .001) were correlated to an increased early death. In addition, D-TLA was an independent predictor of early mortality. Area under the curve of D-TLA was 0.849 (95% confidence interval 0.730–0.967) for predicting early mortality and 0.742 (95% CI 0.611–0.873) for predicting early adverse events. Survival and event-free survival rates during follow-up were decreased in the D-TLA > 21.5% group compared with the D-TLA ≤ 21.5% group (all P < .001).ConclusionsLarger D-TLA is correlated with worse postoperative outcomes and might be a crucial parameter for future risk stratification in patients with cTBAD.  相似文献   
5.
目的:评定LC-MS/MS法测定人血浆中布康唑浓度的不确定度。方法:分析测定过程中不确定度的来源,包括对照品的称量、仪器误差、标准溶液的配制、含药血浆样品的配制、血浆样品的处理、标准曲线的拟合、基质效应、重复性等,评定各来源分量的不确定度,计算合成不确定度和扩展不确定度。结果:人血浆中低(60.0 pg·mL-1)、中(600.0 pg·mL-1)、高(6 400.0 pg·mL-1)浓度布康唑的扩展不确定度分别为5.62,63.90,626.26 pg·mL-1k=2,P=95%)。结论:LC-MS/MS法测定人血浆中布康唑浓度的不确定度主要由基质效应、血浆样品的处理(提取回收率),仪器误差、重复性(精密度)引入。  相似文献   
6.
目的:建立液相色谱-串联质谱法(UPLC-MS/MS)同时测定人血浆中头孢哌酮与舒巴坦的浓度,分析头孢哌酮/舒巴坦血药浓度监测结果,为临床合理用药提供参考。方法:以氯唑沙宗为内标,采用Waters BEHC18柱(2.1 mm×100 mm,1.7 μm)进行分离,通过串联质谱仪,负离子检测模式下,以多反应监测(MRM)方式进行定量测定。对某院2018年以不同给药方案进行治疗的73例住院患者测定的头孢哌酮/舒巴坦血药浓度结果进行分析。结果:头孢哌酮与舒巴坦在测定条件下1~200 mg·L-1范围内线性关系良好,两者日内精密度RSD均<10%,基质效应分别为(72.77±0.99)%与(75.72±0.11)%,提取回收率均>90%。73例患者共监测血药浓度96次,其中不同给药方案2 g,q8 h(43例次);2 g,q12 h(26例次);2 g,q6 h(27例次),各组头孢哌酮血药浓度的中位数分别为34.12 mg·L-1(4.12~177.79 mg·L-1)、31.23 mg·L-1(1.89~251.8 mg·L-1)、59.96 mg·L-1(1.77~140.58 mg·L-1),舒巴坦血药浓度的中位数分别为6.3 mg·L-1(0.61~136.01 mg·L-1)、28.83 mg·L-1(0.5~133.69 mg·L-1)、11.17 mg·L-1(0.73~143.53 mg·L-1)。Mann-Whitney U检验显示,头孢哌酮血药浓度结果无统计学差异(P>0.05),舒巴坦有统计学差异(P<0.05)。结论:本检测方法操作简便、快速、重复性好,可满足临床头孢哌酮与舒巴坦浓度的检测;头孢哌酮/舒巴坦在不同给药方案下血药浓度结果与个体差异相关,有必要开展血药浓度监测并依据结果适时调整用药方案,提高治疗效果减少耐药率的发生。  相似文献   
7.
This study aimed at evaluating how encapsulation in a regular nanocarrier (NC) (providing extended circulation time) or in a brain-targeting NC (providing prolonged circulation time and increased brain uptake) may influence the therapeutic index compared with the unformulated drug and to explore the key parameters affecting therapeutic performance using a model-based approach. Pharmacokinetic (PK) models were built with chosen PK parameters. For a scenario where central effect depends on area under the unbound brain concentration curve and peripheral toxicity relates to peak unbound plasma concentration, dose-effect and drug-side effect curves were constructed, and the therapeutic index was evaluated. Regular NC improved the therapeutic index compared with the unformulated drug due to reduced peripheral toxicity, while brain-targeting NC enhanced the therapeutic index by lowering peripheral toxicity and increasing central effect. Decreasing drug release rate or systemic clearance of NC with drug still encapsulated could increase the therapeutic index. Also, a drug with shorter half-life would therapeutically benefit more from a NC encapsulation. This work provides insights into how a NC for brain delivery should be optimized to maximize the therapeutic performance and is helpful to predict if and to what extent a drug with certain PK properties would obtain therapeutic benefit from nanoencapsulation.  相似文献   
8.
9.
目的首先确定中毒药物,然后通过测定血药浓度以了解中毒程度,为重度苯妥英钠中毒患者临床抢救治疗提供依据。方法间隔一定时间采集患者静脉血,萃取血中药物,在211 nm处以反相高效液相色谱法定性,明确中毒药物并测定血药浓度。结果在苯妥英中毒患者中最高血药浓度为68.94 mg.L-1,接近治疗浓度上限的3.5倍。结论患者为重度中毒,危及生命,需临床药师与临床医师积极配合,施行全程药学监护。  相似文献   
10.
Summary Eight patients with malignant gliomas verified on CT scan, received an intravenous injection of 50 mg of Adriamycin R, 24 hours prior to surgical removal of the tumour. Peroperatively, both tumour and surrounding tissue specimens were obtained for determination of the tissue concentrations of Adriamycin and its reduced metabolite Adriamycinol. It was found that Adriamycin could be detected in tumour tissue from all patients. The concentration varied between 0,9 and 4,6 nmol/g tissue. In contrast, Adriamycin could only be detected in surrounding brain tissue from one patient.In anin vitro study a human malignant glioma cell line (U-251 MG) was exposed to various concentrations of Adriamycin for 24 hours. It was found that an intracellular drug concentration above 30 nmol/g cells caused a concentration dependent inhibition of cell growth. Thus, it is likely that the poor effect of Adriamycin on patients with malignant gliomas is due to an ineffective drug accumulation in the tumour tissue.  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