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   63470篇
  免费   5023篇
  国内免费   2683篇
耳鼻咽喉   291篇
儿科学   1858篇
妇产科学   612篇
基础医学   13433篇
口腔科学   507篇
临床医学   4587篇
内科学   15097篇
皮肤病学   689篇
神经病学   1333篇
特种医学   731篇
外国民族医学   7篇
外科学   2644篇
综合类   7651篇
现状与发展   20篇
一般理论   2篇
预防医学   13971篇
眼科学   415篇
药学   3611篇
  17篇
中国医学   971篇
肿瘤学   2729篇
  2024年   19篇
  2023年   1074篇
  2022年   1315篇
  2021年   2721篇
  2020年   2405篇
  2019年   2128篇
  2018年   2161篇
  2017年   2067篇
  2016年   2375篇
  2015年   2773篇
  2014年   3779篇
  2013年   4371篇
  2012年   3775篇
  2011年   4559篇
  2010年   3844篇
  2009年   3354篇
  2008年   2941篇
  2007年   3219篇
  2006年   2882篇
  2005年   2499篇
  2004年   2230篇
  2003年   1925篇
  2002年   1525篇
  2001年   1455篇
  2000年   1201篇
  1999年   1057篇
  1998年   831篇
  1997年   819篇
  1996年   640篇
  1995年   715篇
  1994年   665篇
  1993年   538篇
  1992年   404篇
  1991年   356篇
  1990年   322篇
  1989年   298篇
  1988年   275篇
  1987年   199篇
  1986年   176篇
  1985年   357篇
  1984年   213篇
  1983年   156篇
  1982年   140篇
  1981年   116篇
  1980年   73篇
  1979年   65篇
  1978年   59篇
  1977年   35篇
  1976年   33篇
  1974年   10篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
51.
目的:采用文献检索的方法对N-乙酰半胱氨酸辅助治疗呼吸道病毒的研究进行汇总分析,评价其有效性与安全性,对现阶段临床辅助治疗新型冠状病毒肺炎提供理论依据和临床证据。方法:以"乙酰半胱氨酸""N-acetylcysteine""流感病毒"为关键词,系统检索CNKI、万方、维普、SinoMed、Pubmed数据库,筛选文章,提取数据,进行分析。结果:共纳入16篇研究论文,包括动物试验、细胞试验以及案例报道,病毒涉及流感病毒、呼吸道合胞病毒以及腺病毒。N-乙酰半胱氨酸主要通过抑制NF-κB向细胞核的移位和MAPK p38的磷酸化两条途径发挥其抗氧化作用,进而抑制减轻肺组织炎症、肺水肿。结论:相关的细胞研究与动物研究证明N-乙酰半胱氨酸对呼吸道病毒有一定的抑制作用,能够减轻流感和流感样发作。并且由于其良好的祛痰作用,对于新冠肺炎患者症状可能有较好的改善作用。  相似文献   
52.
目的乳腺癌患者受疾病或抗肿瘤治疗的影响,机体处于免疫低下状态,是2019新型冠状病毒肺炎(corona virus disease 2019,COVID-19)的易感人群之一。本研究为乳腺癌患者在COVID-19疫情期间提出诊疗建议。方法应用维普、知网、PubMed检索系统,以"新型冠状病毒肺炎、乳腺癌、指南、延迟、时机"或"COVID-19、breast cancer、guidelines、delaying、timeliness"等为检索词,检索2014-01-2020-01相关文献,共检索到英文文献19篇,中文文献12篇。纳入标准:(1)报道乳腺癌手术、化疗、放疗或内分泌治疗延迟治疗情况;(2)有关COVID-19诊治流程管理;(3)乳腺癌诊治指南。根据标准共纳入20篇文献。结果针对目前国内的疫情,对于常规复查患者,在病情稳定情况下可暂缓复查。对于晚期患者维持治疗阶段,应根据患者症状、肿瘤负荷,适当简化检查,重点检查靶病灶或症状明显的器官。对于内分泌治疗、靶向维持治疗、进行骨相关治疗、化疗及放疗的患者,应根据疾病分期和治疗阶段,维持或调整治疗方案。对于乳腺癌手术患者,可短时间暂缓手术。如确定要实施手术,应尽可能缩小手术范围,缩短手术时间。结论在COVID-19疫情的特殊时期,乳腺癌患者的治疗应遵循指南,合理诊治,科学防护。  相似文献   
53.
To obtain baseline data for cervical cancer prevention in Japan, we analyzed human papillomavirus (HPV) data from 5045 Japanese women aged less than 40 years and diagnosed with cervical abnormalities at 21 hospitals during 2012‐2017. These included cervical intraepithelial neoplasia grade 1 (CIN1, n = 573), CIN2‐3 (n = 3219), adenocarcinoma in situ (AIS, n = 123), and invasive cervical cancer (ICC, n = 1130). The Roche Linear Array was used for HPV genotyping. The HPV type‐specific relative contributions (RCs) were estimated by adding multiple infections to single types in accordance with proportional weighting attributions. Based on the comparison of type‐specific RCs between CIN1 and CIN2‐3/AIS/ICC (CIN2+), RC ratios were calculated to estimate type‐specific risks for progression to CIN2+. Human papillomavirus DNA was detected in 85.5% of CIN1, 95.7% of CIN2‐3/AIS, and 91.2% of ICC. Multiple infections decreased with disease severity: 42.9% in CIN1, 40.4% in CIN2‐3/AIS, and 23.7% in ICC (P < .0001). The relative risk for progression to CIN2+ was highest for HPV16 (RC ratio 3.78, 95% confidence interval [CI] 3.01‐4.98), followed by HPV31 (2.51, 1.54‐5.24), HPV18 (2.43, 1.59‐4.32), HPV35 (1.56, 0.43‐8.36), HPV33 (1.01, 0.49‐3.31), HPV52 (0.99, 0.76‐1.33), and HPV58 (0.97, 0.75‐1.32). The relative risk of disease progression was 1.87 (95% CI, 1.71‐2.05) for HPV16/18/31/33/35/45/52/58, but only 0.17 (95% CI, 0.14‐0.22) for HPV39/51/56/59/66/68. Human papillomavirus 16/18/31/33/45/52/58/6/11 included in a 9‐valent vaccine contributed to 89.7% (95% CI, 88.7‐90.7) of CIN2‐3/AIS and 93.8% (95% CI, 92.4‐95.3) of ICC. In conclusion, our data support the Japanese guidelines that recommend discriminating HPV16/18/31/33/35/45/52/58 genotypes for CIN management. The 9‐valent vaccine is estimated to provide over 90% protection against ICC in young Japanese women.  相似文献   
54.
Cancer stem cells (CSCs) play a decisive role in the development and progression of cancer. To investigate CSCs in Epstein‐Barr virus (EBV)‐associated carcinoma (EBVaGC), we screened previously reported stem cell markers of gastric cancer in EBV‐infected gastric cancer cell lines (TMK1 and NUGC3) and identified CD44v6v9 double positive cells as candidate CSCs. CD44v6/v9+/+ cells were sorted from EBVaGC cell line (SNU719) cells and EBV‐infected TMK1 cells and these cell populations showed high spheroid‐forming ability and tumor formation in SCID mice compared with the respective CD44v6/v9?/? cells. Sphere‐forming ability was dependent on the nuclear factor‐κB (NF‐κB) signaling pathway, which was confirmed by decrease of sphere formation ability under BAY 11‐7082. Small interfering RNA knockdown of latent membrane protein 2A (LMP2A), one of the latent gene products of EBV infection, decreased spheroid formation in SNU719 cells. Transfection of the LMP2A gene increased the sphere‐forming ability of TMK1 cells, which was mediated through NF‐κB signaling. Together, these results indicate that CD44v6v9+/+ cells are CSCs in EBVaGC that are maintained through the LMP2A/NF‐κB pathway. Future studies should investigate CD44v6/v9+/+ cells in normal and neoplastic gastric epithelium to prevent and treat this specific subtype of gastric cancer infected with EBV.  相似文献   
55.
宫颈癌是影响全球女性健康的公共卫生问题。持续的高危型HPV感染是宫颈癌的主要致病因素。目前,HPV预防性疫苗已经在全球范围内逐渐广泛开展,但其对已感染HPV的女性没有治疗作用。迄今,多种治疗性疫苗已用于临床前模型和临床试验,包括肽和蛋白质疫苗、活载体疫苗、DNA疫苗等,并已经显示出良好的安全性和耐受性,为宫颈癌的防治工作带来了希望和动力。但其仍存在免疫原性低、需要寻找更多新的靶抗原基因等不足,仍需进一步研究。  相似文献   
56.

Background

Vaccination of children with 13-valent pneumococcal conjugate vaccine (PCV13) led to declines in vaccine-type pneumococcal nasopharyngeal carriage among adults through indirect effects. In August 2014, PCV13 immunization of all U.S. adults ≥65?years of age was recommended. This study sought to define prevalence and serotype distribution of pneumococcal carriage among adults ≥65?years of age and to describe risk factors for colonization soon after introduction of PCV13 in adults.

Methods

A cross-sectional survey of non-institutionalized U.S. adults ≥65?years of age was conducted in four states in 2015–2016. Demographic information, risk factors for disease, PCV13 vaccination history, and nasopharyngeal (NP) and oropharyngeal (OP) swabs were collected. NP and OP swabs were processed separately and pneumococcal isolates were serotyped by Quellung reaction. Antimicrobial susceptibility of pneumococcal isolates was performed. NP swabs also underwent real-time PCR for pneumococcal detection and serotyping.

Results

Of 2989 participants, 45.3% (1354/2989) had been vaccinated with PCV13. Fifty-five (1.8%) carried pneumococcus (45 identified by culture and 10 by real-time PCR only) and PCV13 serotypes were found in eight (0.3%) participants. Almost half (22/45) of pneumococcal isolates were not susceptible to at least one of the antibiotics tested. Vaccine-type carriage among vaccinated and unvaccinated individuals was similar (0.2% vs. 0.1%, respectively). Respiratory symptoms were associated with higher odds of pneumococcal colonization (adjusted OR: 2.1; 95% CI?=?1.1–3.8).

Conclusions

Pneumococcal carriage among non-institutionalized adults ≥65?years of age was very low. Less than 0.5% of both vaccinated and unvaccinated individuals in our study carried vaccine-type serotypes. Over a decade of PCV vaccination of children likely led to indirect effects in adults. However, given the low vaccine-type carriage rates we observed in an already high PCV13 adult coverage setting, it is difficult to attribute our findings to the direct versus indirect effects of PCV13 on adult carriage.  相似文献   
57.

Background

A nasal influenza vaccine has been available only in a live attenuated form, which limits the range of recipients to immune-competent individuals. The present study evaluated a newly developed intranasal inactivated influenza vaccine with a novel adjuvant, heat-labile enterotoxin (LT) derived from E. coli (LTh(αK)).

Methods

The study was a randomized, double-blind, controlled phase I trial to evaluate the safety and immunogenicity of an intranasal vaccine containing the trivalent influenza HA antigen (7.5?µg each of A/California/7/09 (H1N1)-like virus, A/Victoria/210/2009 (H3N2) virus, and B/Brisbane/60/2008-like virus) in combination with 4 different doses of adjuvant LTh(αK) (7.5, 15, 30 or 45?μg) and 22.5?μg of influenza HA antigen alone (control vaccine). The vaccine was intranasally administered on Days 0 and 7. A safety evaluation commenced for 180?days, and hemagglutination inhibition (HI) antibody titers and nasal HA-specific IgA titers on Day 0 and Day 28 were assessed to determine whether an immunogenic response was elicited.

Results

From November 2012 to September 2013, a total of 36 subjects were enrolled. Twenty-four subjects received an adjuvanted vaccine, and 12 subjects received a control vaccine. The most common adverse event (AE) was mild nasal discomfort, and systemic AEs were mild fatigue and headache. Only two subjects discontinued the study because of an AE (one had grade 3 fever, and one had nodal arrhythmia). In the group with 45?μg of LTh(αK), the seroprotection rates were 100%, 100% and 80%, and the nasal IgA conversion factors were 7.90, 7.46 and 12.27 for the A/H3N2, A/H1N1 and split B strains, respectively. Adjuvant LTh(αK) vaccine showed a significant enhancement in mucosal immunity in split B -specific IgA.

Conclusion

The intranasal inactivated influenza vaccine is generally safe, and the LTh(αK)-adjuvanted vaccine is more immunogenic than non-adjuvanted control vaccine.ClinicalTrials.gov Identifier: NCT03293732.  相似文献   
58.
伍磊  张志鹏  蔡文涛  温海梅  陈勇 《中草药》2020,51(24):6367-6376
乙肝病毒是一种能导致机体产生急性或慢性乙型肝炎(乙肝)的嗜肝性DNA病毒。乙肝现已成为全球性公共卫生疾病,易恶化发展为肝硬化、肝衰竭,甚至肝癌,严重威胁着人类的健康。中药及其活性成分发挥着重要的抗乙肝病毒活性,对中药抗乙肝病毒活性及其作用机制进行综述,以期为今后抗乙肝病毒研究提供一定的参考。  相似文献   
59.
Objectives: There are disparities in the uptake of HPV vaccine among racial/ethnic minority women. The strongest predictor of HPV vaccine uptake among adult women is health care provider (HCP) recommendation; however, it is unclear how issues relating to race/ethnicity may mitigate these recommendations. Research shows that racial/ethnic and gender concordance between a patient and HCP can improve patient satisfaction, access and quality of care. If concordance contributes to improved patient-provider interactions, then it may be a factor in patient decisions regarding HPV vaccination. The objectives of this study were to (1) explore gender and ethnicity HCP preference regarding HPV vaccination among unvaccinated; and (2) understand factors associated with those preferences.

Design: Unvaccinated Latina college students (n?=?187) completed a survey that assessed HCP preferences, medical mistrust, cultural assimilation and HPV vaccine recommendation. Logistic regression models evaluated associations between above variables with HPV knowledge and preference for a female and/or Latina HCP.

Results: Most respondents had health insurance (71%), a regular HCP (64%), were US-born (67%), with foreign-born parents (74%). Thirty-four percent and 18% agreed that they would be more likely to get the HPV vaccine if the recommending HCP was female and Latino, respectively. Latina women reporting higher medical mistrust preferred a HPV vaccine recommendation from a Latino/a provider.

Conclusions: Latinas’ preferences regarding gender and ethnicity of their HCPs may affect patient-provider interactions. Increasing diversity and cultural awareness among HCPs, and providing linguistically and culturally-appropriate information may decrease patient-provider mistrust, increase uptake of the HPV vaccine, and decrease persistent cervical cancer disparities.  相似文献   

60.
B cells are recognized as the main effector cells of humoral immunity which suppress tumor progression by secreting immunoglobulins, promoting T cell response, and killing cancer cells directly. Given these properties, their anti-tumor immune response in the tumor micro-environment (TME) is of great interest. Although T cell-related immune responses have become a therapeutic target with the introduction of immune checkpoint inhibitors, not all patients benefit from these treatments. B cell and B cell-related pathways (CCL19, −21/CCR7 axis and CXCL13/CXCR5 axis) play key roles in activating immune response through humoral immunity and local immune activation via tertiary lymphoid structure (TLS) formation. However they have some protumorigenic works in the TME. Thus, a better understanding of B cell and B cell-related pathways is necessary to develop effective cancer control. In this review, we summarize recent evidences regarding the roles of B cell and B cell-related pathways in the TME and immune response and discuss their potential roles for novel cancer treatment strategies.  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