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   12214篇
  免费   1321篇
  国内免费   806篇
耳鼻咽喉   108篇
儿科学   105篇
妇产科学   151篇
基础医学   1450篇
口腔科学   236篇
临床医学   1696篇
内科学   1756篇
皮肤病学   84篇
神经病学   700篇
特种医学   508篇
外国民族医学   7篇
外科学   1192篇
综合类   2223篇
现状与发展   3篇
一般理论   2篇
预防医学   817篇
眼科学   305篇
药学   1330篇
  22篇
中国医学   797篇
肿瘤学   849篇
  2024年   162篇
  2023年   235篇
  2022年   592篇
  2021年   704篇
  2020年   580篇
  2019年   458篇
  2018年   483篇
  2017年   492篇
  2016年   379篇
  2015年   590篇
  2014年   692篇
  2013年   567篇
  2012年   874篇
  2011年   945篇
  2010年   585篇
  2009年   469篇
  2008年   585篇
  2007年   608篇
  2006年   587篇
  2005年   604篇
  2004年   408篇
  2003年   329篇
  2002年   315篇
  2001年   272篇
  2000年   276篇
  1999年   334篇
  1998年   184篇
  1997年   181篇
  1996年   135篇
  1995年   99篇
  1994年   118篇
  1993年   52篇
  1992年   76篇
  1991年   73篇
  1990年   75篇
  1989年   55篇
  1988年   41篇
  1987年   26篇
  1986年   32篇
  1985年   30篇
  1984年   12篇
  1983年   8篇
  1982年   7篇
  1981年   7篇
  1979年   4篇
  1942年   1篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
BackgroundPeptide receptor radionuclide therapy (PRRT) with radiolabeled somatostatin receptor (SSR) analogs is now an established systemic treatment for neuroendocrine tumors (NET). However, more short- and long-term data about renal and hepatotoxicity is needed. Here we present our experience in this clinical scenario.MethodsEighty-six patients with progressive SSR-expressing malignancies underwent PRRT with Lu-177 Dotatate and were followed up for up to 2 years. Laboratory tests were done 1 week before each cycle and every 2 months at follow-up. Hepatic and renal toxicity was determined based on NCI CTCAE V5.0.Results55/86 (64%) patients completed all 4 cycles of PRRT; 18/86 (20.9%) are currently being treated; 13/86 (15.1%) had to discontinue PRRT: 4/13 (31%) due to hematologic toxicity, 9/13 (69%) due to non-PRRT-related comorbidities. Out of the patients who finished treatment, only transient grade 2 toxicities were observed during PRRT: hypoalbuminemia in 5.5% (3/55), and renal toxicity (serum creatinine and estimated glomerular filtration rate) in 1.8% (1/55). No grade 3 or 4 liver and renal toxicity occurred. Patients presenting with impaired liver or renal function prior to PRRT, either improved or had stable findings. No deterioration was observed.ConclusionPeptide receptor radionuclide therapy does not have a negative impact on liver and renal function, even in patients with pre-existing impaired parameters. No grade 3 or 4 hepatic or renal toxicity was identified. Only transient grade 2 hypoalbuminemia in 5.5% and nephrotoxicity in 1.8% of patients were seen during PRRT.  相似文献   
52.
尿白蛋白排泄率与糖尿病中医症状关系的临床研究   总被引:2,自引:0,他引:2  
目的:研究尿白蛋白排泄率与糖尿病患者中医症状的关系,为中医糖尿病的诊断治疗提供一种可量化的方法。方法:测取入选患者的尿白蛋白排泄率和中医证候得分并进行统计分析。结果:糖尿病中医症状表现越严重,尿白蛋白排泄率越高。结论:尿白蛋白排泄率与糖尿病中医证候之间存在固有的联系,可以为中医糖尿病的诊断治疗提供一种可量化的方法,传统的中医证候的科学性可以被现代医学证实。  相似文献   
53.
目的将兔骨髓诱导的内皮细胞接种于纤维蛋白凝胶内并观察其生长增值情况。方法梯度离心分离兔骨髓单个核细胞(MNCs),直接向内皮细胞诱导培养,传代培养至第2代细胞,倒置显微镜观察细胞形态及生长特点,免疫组化鉴定;以10^5密度接种于纤维蛋白凝胶中培养并定期观察细胞生长情况,单纯细胞及胶原内的细胞分别用MTT法检测其生长并绘制生长曲线,胶原切片并作苏木精.伊红染色观察细胞在胶原内的生长。结果诱导的内皮细胞为铺路石样。呈单层生长,第2代细胞CD31、八因子相关抗原免疫组化均为阳性,摄取低密度脂蛋白和结合凝集素实验均阳性;细胞在纤维蛋白凝胶内成立体生长,细胞在纤维蛋白凝胶内3d后成梭形铺开,6d后自发形成管腔样结构;细胞在纤维蛋白凝胶内生长曲线成“s”形。结论骨髓诱导的内皮细胞在纤维蛋白凝胶内生长增值良好,纤维蛋白凝胶可以作为接种骨髓诱导的内皮细胞的基质材料。  相似文献   
54.
The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike is a trimer of S1/S2 heterodimers with three receptor-binding domains (RBDs) at the S1 subunit for human angiotensin-converting enzyme 2 (hACE2). Due to their small size, nanobodies can recognize protein cavities that are not accessible to conventional antibodies. To isolate high-affinity nanobodies, large libraries with great diversity are highly desirable. Dromedary camels (Camelus dromedarius) are natural reservoirs of coronaviruses like Middle East respiratory syndrome CoV (MERS-CoV) that are transmitted to humans. Here, we built large dromedary camel VHH phage libraries to isolate nanobodies that broadly neutralize SARS-CoV-2 variants. We isolated two VHH nanobodies, NCI-CoV-7A3 (7A3) and NCI-CoV-8A2 (8A2), which have a high affinity for the RBD via targeting nonoverlapping epitopes and show broad neutralization activity against SARS-CoV-2 and its emerging variants of concern. Cryoelectron microscopy (cryo-EM) complex structures revealed that 8A2 binds the RBD in its up mode with a long CDR3 loop directly involved in the ACE2 binding residues and that 7A3 targets a deeply buried region that uniquely extends from the S1 subunit to the apex of the S2 subunit regardless of the conformational state of the RBD. At a dose of ≥5 mg/kg, 7A3 efficiently protected transgenic mice expressing hACE2 from the lethal challenge of variants B.1.351 or B.1.617.2, suggesting its therapeutic use against COVID-19 variants. The dromedary camel VHH phage libraries could be helpful as a unique platform ready for quickly isolating potent nanobodies against future emerging viruses.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the etiologic agent of COVID-19 (1, 2) that enters human cells by binding its envelope anchored type I fusion protein (spike) to angiotensin-converting enzyme 2 (ACE2) (3, 4). The SARS-CoV-2 spike is a trimer of S1/S2 heterodimers with three ACE2 receptor-binding domains (RBDs) attached to the distal end of the spike via a hinge region that allows conformational flexibility (4). In the all-down conformation, the RBDs are packed with their long axes contained in a plane perpendicular to the axis of symmetry of the trimer. Transition to the roughly perpendicular up conformation exposes the receptor-binding motif (RBM), located at the distal end of the RBD, which is sterically occluded in the down state. Numerous neutralizing antibodies targeting the spike, particularly its RBD, have been developed to treat COVID-19 using common strategies such as single B cell cloning, animal immunization, and phage display (59). Most vaccines, including those that are messenger RNA based, are designed to induce immunity against the spike or RBD (1012). However, emerging SARS-CoV-2 variants such as D614G, B.1.1.7 (Alpha, United Kingdom), B.1.351 (Beta, South Africa), and P.1 (Gamma, Brazil) have exhibited increased resistance to neutralization by monoclonal antibodies or postvaccination sera elicited by the COVID-19 vaccines (13, 14). Monoclonal antibodies with Emergency Use Authorization for COVID-19 treatment partially (Casirivimab) or completely (Bamlanivimab) failed to inhibit the B.1.351 and P.1 variants. Similarly, these variants were less effectively inhibited by convalescent plasma and sera from individuals vaccinated with a COVID-19 vaccine (BNT162b2) (13). The B.1.617.2 (Delta, India) variant became the prevailing strain in many countries (15). Highly effective and broadly neutralizing antibody therapy is urgently demanded for COVID-19 patients.Due to their small size and unique conformations, camelid VHH single-domain antibodies (also known as nanobodies) can recognize protein cavities that are not accessible to conventional antibodies (16). To isolate high-affinity nanobodies without a need for further affinity maturation, it is highly desirable to construct large nanobody libraries with great diversity. Dromedary camels have been found as potential natural reservoirs of Middle East respiratory syndrome CoV (MERS-CoV) (17). We speculated that dromedary camels would be an ideal source of neutralizing nanobodies against coronaviruses. In the present study, we built large camel VHH single-domain antibody phage libraries with a diversity of over 1011 from six dromedary camels (Camelus dromedarius), three males and three females, with ages ranging from 3 mo to 20 y. We used both the SARS-CoV-2 RBD and the stabilized spike ectodomain trimer protein as baits to conduct phage panning for nanobody screening. Among all the binders, we found NCI-CoV-7A3 (7A3), NCI-CoV-1B5 (1B5), NCI-CoV-8A2 (8A2), and NCI-CoV-2F7 (2F7) to be potent ACE2 blockers. In addition, these dromedary camel nanobodies displayed potent neutralization activity against the B.1.351 and B.1.1.7 variants and the original strain (Wuhan-Hu-1). The cryoelectron microscopy (cryo-EM) structure of the spike trimer protein complex with these VHH nanobodies revealed two distinct nonoverlapping epitopes for neutralizing SARS-CoV-2. In particular, 7A3 recognizes a unique and deeply buried region that extends to the apex of the S2 subunit of the spike. Combined treatment with 7A3 and 8A2 shows more potent protection against various variants in culture and mice infected with the B.1.351 variant. Interestingly, 7A3 alone retains its neutralization activity against the lethal challenge of the B.1.617.2 variant in mice.  相似文献   
55.
Acoustic metamaterials based on Helmholtz resonance have perfect sound absorption characteristics with the subwavelength size, but the absorption bandwidth is narrow, which limits the practical applications for noise control with broadband. On the basis of the Fabry–Perot resonance principle, a novel sound absorber of the acoustic metamaterial by parallel connection of the multiple spiral chambers (abbreviated as MSC-AM) is proposed and investigated in this research. Through the theoretical modeling, finite element simulation, sample preparation and experimental validation, the effectiveness and practicability of the MSC-AM are verified. Actual sound absorption coefficients of the MSC-AM in the frequency range of 360–680 Hz (with the bandwidth Δf1 = 320 Hz) are larger than 0.8, which exhibit the extraordinarily low-frequency sound absorption performance. Moreover, actual sound absorption coefficients are above 0.5 in the 350–1600 Hz range (with a bandwidth Δf2 = 1250 Hz), which achieve broadband sound absorption in the low–middle frequency range. According to various actual demands, the structural parameters can be adjusted flexibly to realize the customization of sound absorption bandwidth, which provides a novel way to design and improve acoustic metamaterials to reduce the noise with various frequency bands and has promising prospects of application in low-frequency sound absorption.  相似文献   
56.
临床带教老师要注重培养护生的“慎独”修养   总被引:2,自引:0,他引:2  
本文从“慎独”修养的含义、“慎独”在护理工作中的重要性出发,就如何培养和锻炼实习 护生阐述了自己的观点,临床带教老师应通过言传身教,使实习护生提高认识,刻意追求,努力达到 “慎独”。  相似文献   
57.
Both monetary loss and pain have been studied for decades, but evidence supporting the relationship between them is still lacking. We conducted a meta‐analysis to explore the overlapping brain regions between monetary loss and pain, including physical pain and social pain. Regardless of the type of pain experienced, activation of the anterior insula was a shared neural representation of monetary loss and pain. The network representation pattern of monetary loss was more similar to that of social pain than that of physical pain. In conclusion, our research provided evidence of the common neural correlates of monetary loss and pain.  相似文献   
58.
This study investigated the anti-corrosion performance of commercial amino alcohol migratory corrosion inhibitors (MCIs) on concrete that underwent varying degrees of chloride erosion. Electrochemical impedance spectroscopy (EIS), potentiodynamic polarization (PD), scanning electron microscopy, and energy dispersive spectroscopy (SEM-EDS) analyses were performed to study the anti-corrosion performance and mechanism of the MCIs on the steel bars. The results indicated that the corrosion resistance of the steel bars in concrete was significantly improved by coating with the MCIs, and the earlier the specimens were coated with the MCIs, the higher the anti-corrosion efficiency. The anti-corrosion efficiency was 55.35% when the MCIs coating was applied before chloride erosion; however, the anti-corrosion efficiency decreased to 3.40% when the MCIs coating was applied after the ninth drying–wetting cycle. The improvement in corrosion resistance of the steel bar in concrete coated with MCIs was due to the protective MCIs-molecule film that formed on the steel bar surfaces, and the oxidative dissolution of iron at the anode was effectively inhibited by the MCIs coating.  相似文献   
59.
AimThe investigation aims to evaluate the potential effect of Shugan Granule (SGKL) on the gut, brain, and behaviors in rats exposed to chronic restraint stress (CRS).MethodsThe fecal microbiota and metabolite changes were studied in rats exposed to CRS and treated with SGKL (0.1 mg/kg/day). Depressive behaviors of these rats were determined through an open‐field experiment, forced swimming test, sucrose preference, and weighing. Moreover, LPS‐stimulated microglia and CRS‐stimulated rats were treated with SGKL to investigate the regulation between SGKL and the PI3K/Akt/pathway, which is inhibited by LY294002, a PI3K inhibitor.Results(i) SGKL improved the altered behaviors in CRS‐stimulated rats; (ii) SGKL ameliorated the CRS‐induced neuronal degeneration and tangled nerve fiber and also contributed to the recovery of intestinal barrier injury in these rats; (iii) SGKL inhibited the hippocampus elevations of TNF‐α, IL‐1β, and IL‐6 in response to CRS modeling; (iv) based on the principal coordinates analysis (PCoA), SGKL altered α‐diversity indices and shifted β‐diversity in CRS‐stimulated rats; (v) at the genus level, SGKL decreased the CRS‐enhanced abundance of Bacteroides; (vi) Butyricimonas and Candidatus Arthromitus were enriched in SGKL‐treated rats; (vii) altered gut microbiota and metabolites were correlated with behaviors, inflammation, and PI3K/Akt/mTOR pathway; (viii) SGKL increased the LPS‐decreased phosphorylation of the PI3K/Akt/mTOR pathway in microglia and inhibited the LPS‐induced microglial activation; (ix) PI3K/Akt/mTOR pathway inactivation reversed the SGKL effects in CRS rats.ConclusionSGKL targets the PI3K/Akt/mTOR pathway by altering gut microbiota and metabolites, which ameliorates altered behavior and inflammation in the hippocampus.  相似文献   
60.
Objective In order to obtain mature insulin-like growth factor- Ⅱ ( IGF- Ⅱ ), we used Bac-to-Bac baculovirus expression system. Methods Firstly the IGF- Ⅱ cDNA was cloned into a donor plasmid pFastBac1 and the recombinant pFastBac1 was then introduced into competent cells DH 10Bac. Recombinant bacmids were constructed by transposing a mini-Tn7 element from a donor plasmid pFastBac1 to the mini-attTn7 attachment site on the bacmid where the Tn7 transposition functions were provided in trans by a helper plasmid, and then used to transfect Sf9 insect cells to get recombinant baculovirus. The recombinant baculovirus was used to infect insect cells. Results Agarose gel analysis showed that recombinant donor plasmid pFastBac1 was constructed successfully; Agarose gel analysis of PCR products confirmed recombinant bacmid ; SDS-PAGE and Western Blotting showed that a 7KD protein band appeared. Conclusion The mature IGF- Ⅱ with immunogenecity has been expressed and produced by using Bac-to-Bac expression system.  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