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   231909篇
  免费   20637篇
  国内免费   5171篇
耳鼻咽喉   3335篇
儿科学   4562篇
妇产科学   3851篇
基础医学   19995篇
口腔科学   7780篇
临床医学   20702篇
内科学   23656篇
皮肤病学   2559篇
神经病学   12474篇
特种医学   6469篇
外国民族医学   12篇
外科学   23140篇
综合类   36095篇
现状与发展   12篇
一般理论   24篇
预防医学   28760篇
眼科学   2129篇
药学   25096篇
  334篇
中国医学   26890篇
肿瘤学   9842篇
  2023年   4347篇
  2022年   6675篇
  2021年   10601篇
  2020年   10727篇
  2019年   11979篇
  2018年   10746篇
  2017年   9333篇
  2016年   8439篇
  2015年   8004篇
  2014年   15401篇
  2013年   16098篇
  2012年   13919篇
  2011年   14723篇
  2010年   11892篇
  2009年   10473篇
  2008年   9852篇
  2007年   9903篇
  2006年   8507篇
  2005年   7288篇
  2004年   5992篇
  2003年   5398篇
  2002年   4228篇
  2001年   3638篇
  2000年   3220篇
  1999年   2678篇
  1998年   2066篇
  1997年   1947篇
  1996年   1589篇
  1995年   1664篇
  1994年   1579篇
  1993年   1388篇
  1992年   1302篇
  1991年   1173篇
  1990年   1054篇
  1989年   991篇
  1988年   927篇
  1987年   896篇
  1986年   785篇
  1985年   2094篇
  1984年   2371篇
  1983年   1464篇
  1982年   1934篇
  1981年   1376篇
  1980年   1192篇
  1979年   1068篇
  1978年   891篇
  1977年   700篇
  1976年   824篇
  1975年   575篇
  1974年   473篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
《Vaccine》2022,40(6):904-911
BackgroundGSK initiated a Pregnancy Registry in the United States (US) for the reduced-antigen-content tetanus-diphtheria-acellular pertussis (Tdap; Boostrix, GSK) vaccine with the aim to detect and describe pregnancy outcomes in women vaccinated with Boostrix 28 days before estimated conception or during pregnancy.MethodsVoluntary reports of pregnancy exposure to Boostrix received from spontaneous and post-marketing surveillance sources in the US were assessed. Reports were classified as prospective or retrospective based on the knowledge of pregnancy outcomes at the time of reporting. For completeness, reports of exposure to Boostrix or to the Tdap-inactivated poliovirus vaccine (Boostrix-IPV, GSK) reported to the global safety database from countries outside the US were also evaluated.ResultsFrom May 2005 to August 2019, 1517 (1455 prospective and 62 retrospective) pregnancy reports were received in the Boostrix US Pregnancy Registry. Of the prospective reports, 250 had known outcomes: 244 live infants with no apparent birth defects (BDs), three live infants with BDs, and three spontaneous abortions with no apparent BDs. Of the retrospective reports, 55 had known outcomes: 33 live infants with no apparent BDs, 16 live infants with BDs, one spontaneous abortion with no apparent BDs, four stillbirths with no apparent BDs, and one stillbirth with BDs. Cumulatively, 1321 pregnancy reports (1006 for Boostrix; 315 for Boostrix-IPV) were received from countries outside the US. Of these, 163 prospective reports and 551 retrospective reports had known outcomes. Results were in line with those from the Boostrix US Pregnancy Registry.ConclusionsData currently available from the Boostrix US Pregnancy Registry and from countries outside the US suggested that exposure to Boostrix or Boostrix-IPV during pregnancy does not raise safety concerns related to adverse pregnancy outcomes or BDs.  相似文献   
32.
《Vaccine》2022,40(16):2370-2378
Porcine reproductive and respiratory syndrome virus (PRRSV) and Mycoplasma hyopneumoniae (M. hyopneumoniae, Mhp) are two of the most common pathogens involved in the porcine respiratory disease complex (PRDC) resulting in significant economic losses worldwide. Vaccination is the most effective approach to disease prevention. Since PRRSV and Mhp co-infections are very common, an efficient dual vaccine against these pathogens is required for the global swine industry. Compared with traditional vaccines, multi-epitope vaccines have several advantages, they are comparatively easy to produce and construct, are chemically stable, and do not have an infectious potential. In this study, to develop a safe and effective vaccine, B cell and T cell epitopes of PRRSV-GP5, PRRSV-M, Mhp-P46, and Mhp-P65 protein had been screened to construct a recombinant epitope protein rEP-PM that has good hydrophilicity, strong antigenicity, and high surface accessibility, and each epitope is independent and complete. After immunization in mice, rEP-PM could induce the production of high levels of antibodies, and it had good immunoreactivity with anti-rEP-PM, anti-PRRSV, and anti-Mhp antibodies. The anti-rEP-PM antibody specifically recognizes proteins from PRRSV and Mhp. Moreover, rEP-PM induced a Th1-dominant cellular immune response in mice. Our results showed that the rEP-PM protein could be a potential candidate for the development of a safe and effective multi-epitope peptide combined vaccine to control PRRSV and Mhp infections.  相似文献   
33.
《Vaccine》2022,40(33):4748-4763
This work identifies the innovations that made it possible for the Bio-Manguinhos/Fiocruz Immunobiological Technology Institute to engage in the entire production of the Oxford/AstraZeneca vaccine (ChAdOx1 nCov-19) in Brazil, just 1.8 years after the COVID-19 pandemic was declared. The results were summarized in a case-based innovation model composed of 11 workstreams, 32 stages, 22 gates, 11 innovations, and 38 events. In terms of research contributions, three were found: (i) the identification of firm and government-level innovations allowing the substantial reduction in the COVID-19 vaccine time-to-market in Brazil; (ii) the presentation of empirical evidence supporting the new Outbreak Paradigm for vaccine research, development, and production; and (iii) the proposition of a conceptual model for describing innovations through the vaccine value chain in pandemic contexts, particularly when technology transfer is involved.  相似文献   
34.
多囊卵巢综合征(polycystic ovary syndrome,PCOS)是一种内分泌代谢紊乱综合征,临床表现高度异质性。肥胖是PCOS异质性临床表现之一,超过50%的PCOS患者超重或肥胖。肥胖型PCOS主要表现为高雄激素血症、中心型肥胖和糖脂代谢紊乱,非肥胖型PCOS主要表现为黄体生成激素(luteinizing hormone,LH)水平异常升高。尽管肥胖型和非肥胖型PCOS均存在内分泌代谢异常,然而肥胖可加重PCOS糖脂代谢紊乱;肥胖型PCOS还表现脂肪代谢的异常。综述肥胖型PCOS患者的临床特征、性激素水平、糖脂代谢特征,旨在为肥胖型和非肥胖型PCOS患者新的分型诊治提供参考。  相似文献   
35.
36.
37.
BackgroundIn order to avoid excessive treatment of thyroid nodules in the clinic, it is necessary to find a simple and practical analysis method to comprehensively and accurately reflect benign or malignant thyroid nodules. This study aimed to construct and validate a comprehensive and reliable network-based predictive model using a variety of imaging and laboratory criteria for thyroid nodules to stratify the risk of malignancy prior to surgery.MethodsWe retrospectively analyzed data from patients who underwent surgical treatment for thyroid nodules at the Thyroid and Breast Diagnosis and Treatment Center of Weifang Hospital of Traditional Chinese Medicine between January 2018 and December 2020. Binary logical regression analysis was performed to predict whether nodules were malignant or benign. The developmental dataset included 457 patients (January 2018–December 2020). The validation set included separate data points (n = 225, January 2018–December 2020).ResultsIn this study, criteria that showed significant predictive value for malignant nodules included TI-RADS: 4b (p = 0.065); Bethesda IV, Bethesda V, Bethesda VI (P < 0.0001); BRAFV600E mutation (P < 0.0001); Calcitonin>5 pg/ml (p = 0.0037); and FNA-Tg>30 ng/ml (p = 0.0003). A 10-grade risk scoring system was developed. The risk of malignancy risk ranged from 2.06% to 100% and was positively associated with increasing risk grade. The areas under the receiver-operating characteristic curve of the development and validation sets were 0.972 and 0.946, respectively.ConclusionA simple, comprehensive and reliable web-based predictive model was designed using a variety of imaging and laboratory criteria to stratify thyroid nodules by probability of malignancy.  相似文献   
38.
PurposeThe variation in the immune response to Bartonella spp. infection in humans remains unclear. The present study compares the expression of selected interleukins, cytokines and cathelicidin (LL-37) in rheumatology clinic patients suffering from musculoskeletal symptoms with healthy blood donors. The patients had previously been tested for the presence of Bartonella henselae antibodies.MethodsGene expression of LL-37, interleukin (IL)-2, IL-4, IL-6, IL-12, interferon-(IFN)-γ, and tumor necrosis factor (TNF-α)-α was determined in blood samples using quantitative Polymerase Chain Reaction (qPCR). Statistical analysis was prepared with STATISTICA.ResultsStatistically significant differences in the mRNA levels of the tested cytokines (IFN-γ, TNF-α, IL-2, IL-4, IL-6, IL-12; p<0.0001) were observed between the healthy controls and patients; however, no difference was observed for LL37 mRNA (p ?= ?0.1974). No significant differences in mRNA expression were observed between IgG in anti-Bartonella seropositive and seronegative individuals (p>0.05). The only significant differences between the Bartonella spp. DNA positive and negative patients, indicated by PCR, were observed for TNF-α and IL-12 mRNA (p ?= ?0.0045 and p ?= ?0.0255, respectively).ConclusionA broadly similar immune response to the tested cytokines was observed among the participants irrespective of anti-Bartonella spp. IgG seropositivity. However, the Bartonella DNA-positive participants demonstrated significantly lower expression of IL-12 and TNF-α mRNA; this may indicate that these bacteria have a suppressive influence on the immune system.  相似文献   
39.
40.
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