全文获取类型
收费全文 | 36739篇 |
免费 | 2501篇 |
国内免费 | 1363篇 |
专业分类
耳鼻咽喉 | 265篇 |
儿科学 | 2117篇 |
妇产科学 | 1304篇 |
基础医学 | 4744篇 |
口腔科学 | 793篇 |
临床医学 | 3817篇 |
内科学 | 4371篇 |
皮肤病学 | 1232篇 |
神经病学 | 1533篇 |
特种医学 | 742篇 |
外国民族医学 | 6篇 |
外科学 | 1793篇 |
综合类 | 5992篇 |
现状与发展 | 2篇 |
一般理论 | 1篇 |
预防医学 | 2433篇 |
眼科学 | 418篇 |
药学 | 6364篇 |
32篇 | |
中国医学 | 1129篇 |
肿瘤学 | 1515篇 |
出版年
2024年 | 20篇 |
2023年 | 391篇 |
2022年 | 635篇 |
2021年 | 1028篇 |
2020年 | 1039篇 |
2019年 | 1010篇 |
2018年 | 996篇 |
2017年 | 1044篇 |
2016年 | 1079篇 |
2015年 | 1102篇 |
2014年 | 2000篇 |
2013年 | 2145篇 |
2012年 | 1949篇 |
2011年 | 2311篇 |
2010年 | 1922篇 |
2009年 | 1734篇 |
2008年 | 1830篇 |
2007年 | 2011篇 |
2006年 | 1715篇 |
2005年 | 1776篇 |
2004年 | 1421篇 |
2003年 | 1339篇 |
2002年 | 1168篇 |
2001年 | 1053篇 |
2000年 | 962篇 |
1999年 | 875篇 |
1998年 | 777篇 |
1997年 | 730篇 |
1996年 | 566篇 |
1995年 | 632篇 |
1994年 | 566篇 |
1993年 | 412篇 |
1992年 | 374篇 |
1991年 | 279篇 |
1990年 | 186篇 |
1989年 | 154篇 |
1988年 | 134篇 |
1987年 | 125篇 |
1986年 | 115篇 |
1985年 | 146篇 |
1984年 | 140篇 |
1983年 | 115篇 |
1982年 | 116篇 |
1981年 | 110篇 |
1980年 | 82篇 |
1979年 | 67篇 |
1978年 | 46篇 |
1977年 | 50篇 |
1976年 | 44篇 |
1973年 | 20篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
1.
《Vaccine》2022,40(30):4038-4045
PurposeAs protection from COVID-19 following two doses of the BNT162b2 vaccine showed a time dependent waning, a third (booster) dose was administrated. This study aims to compare the antibody response following the third dose versus the second and to evaluate post-booster seroconversion.MethodsA prospective observational study conducted in Maccabi Healthcare Services. Serial SARS-CoV-2 Spike IgG tests, 1,2,3 and 6 months following the second vaccine dose and one month following the third were obtained. Neutralizing antibody levels were measured in a subset of participants. Per individual SARS-CoV-2 Spike IgG titer ratios were calculated one month after the booster administration compared to titers one month following the second dose and prior to booster.ResultsAmong 110 participants, 56 (51%) were women. Mean age was 61.7 ± 1.9 years and 66 (60%) were immunocompromised. One month after third dose, IgG titers were induced 7.83 (95 %CI 5.25–11.67) folds and 2.40 (95 %CI 1.90–3.03) folds compared to one month after the second, in the immunocompromised and immunocompetent groups, respectively. Of the 17 immunocompromised participants who were seronegative after the second dose, 4 (24%) became seropositive following the third. Comparing the titers prior to the third dose, an increase of 50.7 (95 %CI 32.5–79.1) fold in the immunocompromised group and 25.7 (95 %CI 19.1–34.7) fold in and immunocompetent group, was observed.ConclusionA third BNT162b2 vaccine elicited robust humoral response, superior to the response observed following the second, among immunocompetent and immunocompromised individuals. 相似文献
2.
3.
4.
The objectives of this study were to factor analyze the Moral Distress Scale–Revised (MDS-R) in NICU nurses and to evaluate the relationships among dimensions of the MDS-R and the demoralization, exhaustion, and loss of motive dimensions of the Burnout Measure (BM). A total of 142 NICU nurses completed modified pen-and-paper versions of the MDS-R and BM. Exploratory and confirmatory factor analyses showed that the MDS-R-14 was a relatively good fit for the data. The compromised care dimension predicted BM demoralization (β = 0.24) and exhaustion (β = 0.22), the futile care dimension predicted BM exhaustion (β = 0.18), and the untruthful care dimension predicted BM demoralization (β = .25). Strategies to mitigate moral distress and resulting burnout in NICU nurses should address futile care, compromised care, and untruthful care. 相似文献
5.
《Clinical microbiology and infection》2022,28(8):1120-1125
ObjectivesOur aim was to evaluate the effect of the updated European Organization for Research and Treatment of Cancer (EORTC) and Mycoses Study Group 2019 definitions for invasive pulmonary aspergillosis (IPA) on patient classification and the related all-cause 12-week mortality.MethodsIn this retrospective cohort study from our tertiary care centre, we reclassified patients with haematological malignancy who underwent bronchoalveolar lavage between 2014 and 2019 for suspected IPA using the novel EORTC 2019 criteria. We performed receiver operating characteristic curve analysis to define the optimal cut-off for positive PCR and galactomannan and present survival analyses and their possible association with these diagnostic criteria through post hoc comparisons with log rank and Cox regression.ResultsFrom 323 episodes of suspected IPA in 282 patients, 73 were reclassified: 31 (42.5%) from possible to probable IPA, 5 (6.8%) from EORTC criteria not met to probable IPA, and 37 (50.7%) from EORTC criteria not met to possible IPA. Probable IPA increased therefore 11.1% (64/323, 19.8% to 100/323, 30.9%), mostly due to positive PCR (31/36, 86.1%). There was no difference in mortality between newly defined possible and probable IPA (log rank p = 0.950). Mortality was higher in probable cases with lower cycle thresholds (Ct values) versus higher Ct values (p = 0.004). Receiver operating characteristic curve analysis showed an optimal Ct value cut-off of 36.8 with a sensitivity of 75% (95% CI 64.9%–85.1%) and a specificity of 61.7% (95% CI 53.5–69.9) for 12-week mortality.DiscussionThe new EORTC criteria led to 11.1% more probable IPA diagnoses, mostly due to Aspergillus PCR. Restricting positive PCR to below a certain threshold might improve the discrimination of the new EORTC IPA categories for mortality. 相似文献
6.
7.
目的建立一种基于规律成簇的间隔短回文重复序列及其相关蛋白(CRISPR/Cas13a)的乙型肝炎病毒(HBV)共价闭合环状DNA(HBV cccDNA)检测方法。方法提取2017年6月至2020年10月于首都医科大学附属北京佑安医院就诊的4例乙型肝炎患者肝脏总DNA后,使用HindⅢ内切酶和质粒安全性ATP依赖DNA酶(PSAD)分别进行酶切;根据松弛环状DNA(rcDNA)和cccDNA的结构差异,设计特异性扩增HBV cccDNA的引物,对酶切后的产物进行滚环扩增(RCA)和PCR扩增;并筛选crRNA,建立基于CRISPR/Cas13a技术的HBV cccDNA检测新方法。结果利用α-1-抗胰蛋白酶(A1AT)和HBV表面抗原(HBsAg)引物对双重酶切后的产物进行扩增,验证产物中HBV基因组的存在;利用HBV cccDNA和HBV rcDNA引物对PSDA酶切后的产物扩增,验证了产物中只存在HBV cccDNA;利用RCA后的阳性样本作为模板梯度稀释,然后进行PCR扩增转录后使用CRISPR/Cas13a检测,计算出检测下限为10拷贝/μl。结论本研究建立了RCA-PCR-CRISPR-Cas13a的新型检测方法,可对HBV cccDNA进行高灵敏度和高特异性检测,为乙型肝炎患者抗病毒治疗评估、治疗终点的确定以及调整治疗方案提供了有效的监测手段。 相似文献
8.
目的 探讨层流洁净新生儿重症监护病房(NICU)早产儿实施床旁手术的效果与可行性。方法 回顾性分析某军队三甲综合医院2017年9月—2020年10月NICU住院并进行床旁动脉导管扎闭术(PDA)及腹部探查术的危重新生儿的临床资料,在NICU行床旁手术者列为NICU组,转入手术室进行手术者列为手术室(OR)组,比较两组新生儿术后体温、切口感染率及病死率的差异。结果 共计纳入258例新生儿,其中NICU组166例,OR组92例。NICU组新生儿出生胎龄、出生体质量、手术时体质量、新生儿危重病例评分均低于OR组;NICU组新生儿术前应用呼吸机通气比例高于OR组,差异均有统计学意义(均P<0.05)。NICU组与OR组新生儿术中抽检空气培养微生物菌落数、术前体温、PDA与剖腹探查术的构成比例、术后切口感染发病率及病死率比较,差异均无统计学意义(均P>0.05),但手术后OR组新生儿平均体温低于NICU组,差异有统计学意义(P<0.05)。结论 层流洁净NICU早产儿行床旁PDA和腹部手术临床可行,且床旁手术更有利于减少术后低体温的发生。对层流洁净病房进行日常规范化维护,可以有效保障危重早产儿床旁手术的安全。 相似文献
9.
10.
Defining con-founders that affect the reliability of diagnostic tests for coronavirus disease 2019 is vital to breaking the chain of infection. The elderly population is a higher risk group for the emerging virus. However, gender seems to exert a critical role in modifying the infection risk among women owing to hormonal changes. The menopause transition is an exceptional period for older women where the protective and immunomodulatory effects of the estrogen hormone are lost. Accordingly, attention should be given to postmenopausal women since they will have an increased risk compared to their pre-menopausal peers. 相似文献