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   45738篇
  免费   4352篇
  国内免费   1723篇
耳鼻咽喉   304篇
儿科学   847篇
妇产科学   1340篇
基础医学   9493篇
口腔科学   1688篇
临床医学   3696篇
内科学   4987篇
皮肤病学   1253篇
神经病学   2874篇
特种医学   993篇
外国民族医学   20篇
外科学   3135篇
综合类   6965篇
现状与发展   13篇
一般理论   12篇
预防医学   3286篇
眼科学   948篇
药学   5514篇
  19篇
中国医学   1143篇
肿瘤学   3283篇
  2023年   474篇
  2022年   601篇
  2021年   1351篇
  2020年   1292篇
  2019年   1344篇
  2018年   1307篇
  2017年   1439篇
  2016年   1518篇
  2015年   1556篇
  2014年   2456篇
  2013年   3414篇
  2012年   2453篇
  2011年   2698篇
  2010年   2314篇
  2009年   2151篇
  2008年   2088篇
  2007年   2251篇
  2006年   2118篇
  2005年   1931篇
  2004年   1782篇
  2003年   1618篇
  2002年   1379篇
  2001年   1202篇
  2000年   1031篇
  1999年   873篇
  1998年   746篇
  1997年   700篇
  1996年   699篇
  1995年   777篇
  1994年   675篇
  1993年   645篇
  1992年   570篇
  1991年   513篇
  1990年   398篇
  1989年   408篇
  1988年   343篇
  1987年   263篇
  1986年   249篇
  1985年   424篇
  1984年   364篇
  1983年   250篇
  1982年   280篇
  1981年   221篇
  1980年   180篇
  1979年   106篇
  1978年   109篇
  1977年   66篇
  1976年   62篇
  1975年   33篇
  1974年   27篇
排序方式: 共有10000条查询结果,搜索用时 187 毫秒
91.
《Vaccine》2019,37(35):4963-4974
Vaccination is the most efficient strategy to protect from infectious diseases and the induction of a protective immune response not only depends on the nature of the antigen, but is also influenced by the vaccination strategy and the co-administration of adjuvants. Therefore, the precise monitoring of adjuvant candidates and their immune modulatory properties is a crucial step in vaccine development. Here, one central aspect is the induction of appropriate humoral and cellular effector mechanisms.In our study we performed a direct comparison of two promising candidates in adjuvant development, the STING activator bis-(3,5)-cyclic dimeric adenosine monophosphate (c-di-AMP) and the Toll-like receptor ligand formulation poly(I:C)/CpG. These were evaluated in C57BL/6 mice using the model antigen ovalbumin (OVA) in subcutaneous vaccination with soluble protein as well as in a dendritic cell (DC) targeting approach (αDEC-OVA). Strikingly, c-di-AMP as compared to poly(I:C)/CpG resulted in significantly higher antigen-specific IgG antibody levels when used in immunization with soluble OVA as well as in antigen targeting to DC. In vaccination with soluble OVA, c-di-AMP induced a significantly stronger CTL, Th1 and IFNγ-producing CD8+ memory T cell response than poly(I:C)/CpG. The response was CTL and Th1 cell dominated, a profile shared by both adjuvants. In the context of targeting OVA to DC, c-di-AMP induced significantly increased Th1 and Th2 cell responses as compared to poly(I:C)/CpG. Interestingly, the Th1 response dominated the overall T cell response only when c-di-AMP was used, indicating a distinct modulatory property of c-di-AMP when the DC targeting immunization approach was exploited.Taken together, we describe superior properties of c-di-AMP as compared to poly(I:C)/CpG in subcutaneous vaccination with soluble antigen as well as antigen targeting to DC. This indicates exceptionally effective adjuvant properties for c-di-AMP and provides compelling evidence of its potential for further adjuvant development, especially also when using DC targeting approaches.  相似文献   
92.
《Vaccine》2019,37(36):5390-5396
ObjectiveThe purpose of this study was to track and describe the absolute number of vaccine administration errors and corresponding error rates over time and by patient age and vaccine type.MethodsTotal vaccines administered to patients aged 0 through 19 years 364 days from 1/1/2006 through 12/31/2017 at a large academic health system in the Midwest United States with primary, specialty and school-based clinics, and a pediatric hospital were obtained from an electronic medical record. Vaccine administration errors over the same time period for the same patient criteria were analyzed from the health system’s incident reporting system and further compared to the frequency of all incidents reported. Vaccine administration error rates were calculated. Data were analyzed by patient age, vaccine type and year administered.ResultsOf the 1,431,206 vaccine doses given, 552 vaccine administration errors were identified (0.04%). The highest error rates occurred in children aged 2, 3, and 19 years. Vaccine types with the highest error rate were Td, rabies and pneumococcal polysaccharide vaccines. Overall vaccine doses given and errors reported increased over the study period. However, the increase was disproportionate, resulting in an increase in the error rate initially followed by a stabilization at the end of the study period.ConclusionsVaccine administration errors are uncommon. The error rate appears to be stabilizing. Errors are more likely at ages when vaccines are not commonly given, with vaccines that have age-specific dosing and with vaccines that are given less often. This suggests more safety checks are needed for vaccines that are rarely used or given off-schedule, and manufacturers should avoid vaccines with age-specific dosing.  相似文献   
93.
《Vaccine》2019,37(38):5670-5680
Adjuvant Systems (AS) are combinations of immune stimulants that enhance the immune response to vaccine antigens. The first vaccine containing an AS (AS04) was licensed in 2005. As of 2018, several vaccines containing AS04, AS03 or AS01 have been licensed or approved by regulatory authorities in some countries, and included in vaccination programs. These vaccines target diverse viral and parasitic diseases (hepatitis B, human papillomavirus, malaria, herpes zoster, and (pre)pandemic influenza), and were developed for widely different target populations (e.g. individuals with renal impairment, girls and young women, infants and children living in Africa, adults 50 years of age and older, and the general population). Clearly, the safety profile of one vaccine in one target population cannot be extrapolated to another vaccine or to another target population, even for vaccines containing the same adjuvant. Therefore, the assessment of adjuvant safety poses specific challenges. In this review we provide a historical perspective on how AS were developed from the angle of the challenges encountered on safety evaluation during clinical development and after licensure, and illustrate how these challenges have been met to date. Methods to evaluate safety of adjuvants have evolved based on the availability of new technologies allowing a better understanding of their mode of action, and new ways of collecting and assessing safety information. Since 2005, safety experience with AS has accumulated with their use in diverse vaccines and in markedly different populations, in national immunization programs, and in a pandemic setting. Thirteen years of experience using antigens combined with AS attest to their acceptable safety profile. Methods developed to assess the safety of vaccines containing AS have progressed the way we understand and investigate vaccine safety, and have helped set new standards that will guide and support new candidate vaccine development, particularly those using new adjuvants.Focus on the patientWhat is the context? Adjuvants are immunostimulants used to modulate and enhance the immune response induced by vaccination. Since the 1990s, adjuvantation has moved toward combining several immunostimulants in the form of Adjuvant System(s) (AS), rather than relying on a single immunostimulant. AS have enabled the development of new vaccines targeting diseases and/or populations with special challenges that were previously not feasible using classical vaccine technology.What is new? In the last 13 years, several AS-containing vaccines have been studied targeting different diseases and populations. Over this period, overall vaccine safety has been monitored and real-life safety profiles have been assessed following routine use in the general population in many countries. Moreover, new methods for safety assessment, such as a better determination of the mode of action, have been implemented in order to help understand the safety characteristics of AS-containing vaccines.What is the impact? New standards and safety experience accumulated over the last decade can guide and help support the safety assessment of new candidate vaccines during development.  相似文献   
94.
《Vaccine》2019,37(39):5854-5861
BackgroundHepatitis B virus (HBV) remains a major public health issue, although it is a vaccine-preventable disease. Adults with diabetes are at greater risk of contracting HBV than the general population. Commonly used 3-dose HBV vaccines have reduced immunogenicity in older individuals and in those with diabetes mellitus.MethodsIn this post hoc analysis of a phase 3 clinical trial, participants with type 2 diabetes mellitus aged 60–70 years received either 2-dose HBsAg/CpG 1018 (HEPLISAV-B®, n = 327) at 0 and 4 weeks and placebo at 24 weeks or 3-dose HBsAg/alum (Engerix-B®, n = 153) at 0, 4, and 24 weeks. Immunogenicity, including seroprotection rate (SPR) at week 28, and safety were assessed by subgroup (sex, body mass index, and smoking status). SPR was defined as antibody against hepatitis B surface antigen serum concentration ≥10 mIU/mL.ResultsThe SPR at week 28 was significantly higher with HBsAg/CpG 1018 (85.8% [235/274]) than with HBsAg/alum (58.5% [76/130]) in the per-protocol analysis, for an overall difference of 27.3% (95% CI, 18.0–36.8). SPRs with HBsAg/CpG 1018 were consistently markedly higher compared with HBsAg/alum, regardless of sex, body mass index, or smoking status. Adverse events and deaths were comparable between groups.ConclusionsTwo-dose HBsAg/CpG 1018 provides a higher level of seroprotection against HBV than does a 3-dose vaccine (HBsAg/alum) with a similar safety profile in patients aged 60–70 years with type 2 diabetes mellitus.Study identifier: NCT02117934.  相似文献   
95.
  1. The metabolism of the pyrethroids deltamethrin (DLM), cis-permethrin (CPM) and trans-permethrin (TPM) was studied in human expressed cytochrome P450 (CYP) and carboxylesterase (CES) enzymes.

  2. DLM, CPM and TPM were metabolised by human CYP2B6 and CYP2C19, with the highest apparent intrinsic clearance (CLint) values for pyrethroid metabolism being observed with CYP2C19. Other CYP enzymes contributing to the metabolism of one or more of the three pyrethroids were CYP1A2, CYP2C8, CYP2C9*1, CYP2D6*1, CYP3A4 and CYP3A5. None of the pyrethroids were metabolised by CYP2A6, CYP2E1, CYP3A7 or CYP4A11.

  3. DLM, CPM and TPM were metabolised by both human CES1 and CES2 enzymes.

  4. Apparent CLint values for pyrethroid metabolism by CYP and CES enzymes were scaled to per gram of adult human liver using abundance values for microsomal CYP enzymes and for CES enzymes in liver microsomes and cytosol. TPM had the highest and CPM the lowest apparent CLint values for total metabolism (CYP and CES enzymes) per gram of adult human liver.

  5. Due to their higher abundance, all three pyrethroids were extensively metabolised by CES enzymes in adult human liver, with CYP enzymes only accounting for 2%, 10% and 1% of total metabolism for DLM, CPM and TPM, respectively.

  相似文献   
96.
For severely paralyzed people, Brain‐Computer Interfaces (BCIs) can potentially replace lost motor output and provide a brain‐based control signal for augmentative and alternative communication devices or neuroprosthetics. Many BCIs focus on neuronal signals acquired from the hand area of the sensorimotor cortex, employing changes in the patterns of neuronal firing or spectral power associated with one or more types of hand movement. Hand and finger movement can be described by two groups of movement features, namely kinematics (spatial and motion aspects) and kinetics (muscles and forces). Despite extensive primate and human research, it is not fully understood how these features are represented in the SMC and how they lead to the appropriate movement. Yet, the available information may provide insight into which features are most suitable for BCI control. To that purpose, the current paper provides an in‐depth review on the movement features encoded in the SMC. Even though there is no consensus on how exactly the SMC generates movement, we conclude that some parameters are well represented in the SMC and can be accurately used for BCI control with discrete as well as continuous feedback. However, the vast evidence also suggests that movement should be interpreted as a combination of multiple parameters rather than isolated ones, pleading for further exploration of sensorimotor control models for accurate BCI control.  相似文献   
97.
98.
In far too many instances treatment of persons with dementia has reflected a fundamental denial of basic human rights. At times, these individuals are treated worse than the treatment of animals when the five basic freedoms of animals, described by Pachana in her editorial, are implemented. A number of such examples of dehumanizing (and “de-animalizing”) persons with dementia are presented. A case is made for the position that this is the direct result of the “medicalization” of dementia and “Alzheimer Disease.” This has led to the disenfranchisement of persons with dementia and their caregivers regarding the treatment of dementia, while medical “expertise” has led to a paradigm of learned helplessness while waiting for “the cure.” While the medicalization of dementia has been a financial success in terms of funding failed researcher to find a cure, it has been a catastrophe for the quality of life of persons with dementia and their caregivers. It is time to take control of the treatment of dementia back, and especially to listen to the voices of persons with dementia. It is time to take action NOW – to become disruptive to the current paradigm. The emperor and his cure have no clothes. We deserve better. We must make this change in paradigm our mission, to demand it, and to accept nothing less. Power to the people.  相似文献   
99.
Objective: Human epidermal growth factor receptor 2 (erbb2/HER2) overexpression, has now been implicatedin advanced gastric and gastroesophageal junction cancers. The study was conducted to determine the rate of HER2positivity in patients with locally advanced or metastatic gastric and gastroesophageal adenocarcinoma in North-EastIndia and to assess the impact of various demographic and clinical parameters on HER2 positivity. Methods: A total of68 patients of age >18 years of gastric and gastroesophageal adenocarcinoma diagnosed on histopathological examinationfrom September 2016 to February 2018 at Dr B Borooah Cancer Institute, Assam were enrolled for the observational(epidemiological) study. All patients were subjected to the HER2 immunohistochemistry test using a FDA-approved,standardized test kit. HER2 expression was correlated with various demographic and clinicopathological parameters.Results: The overall rate of HER2 positivity in the population studied was 56% (n=38). The rate was non-significantlyhigher in male, older age group (>60 years) and Hindu population. Similarly, HER2 positivity rate was higher in patientswith well differentiated histology and was more common in patients with stage II and III diseases, but neither of theassociations is statistically significant. HER2 positivity rate was significantly higher in proximal and in GEJ tumours(56% versus 44%, P=0.002). Conclusion: HER2 overexpression was evident in 56% of the North-East Indian patientswith locally advanced and metastatic gastric and gastroesophageal adenocarcinoma. The overexpression correlatedsignificantly with primary tumour site. Routine testing of gastric and gastroesophageal tumours for HER2 expressionis recommended to provide a therapeutic advantage in Indian patients.  相似文献   
100.

Background

Resistin is an immunometabolic mediator that is elevated in several inflammatory disorders. A ligand for Toll-like receptor 4, resistin modulates the recruitment and activation of myeloid cells, notably neutrophils. Neutrophils are major drivers of cystic fibrosis (CF) lung disease, in part due to the release of human neutrophil elastase- and myeloperoxidase-rich primary granules, leading to tissue damage. Here we assessed the relationship of resistin to CF lung disease.

Methods

Resistin levels were measured in plasma and sputum from three retrospective CF cohorts spanning a wide range of disease. We also assessed the ability of neutrophils to secrete resistin upon activation in vitro. Finally, we constructed a multivariate model assessing the relationship between resistin levels and lung function.

Results

Plasma resistin levels were only marginally higher in CF than in healthy control subjects. By contrast, sputum resistin levels were very high in CF, reaching 50–100 fold higher levels than in plasma. Among CF patients, higher plasma resistin levels were associated with allergic bronchopulmonary aspergillosis, and higher sputum resistin levels were associated with CF-related diabetes. Mechanistically, in vitro release of neutrophil primary granules was concomitant with resistin secretion. Overall, sputum resistin levels were negatively correlated with CF lung function, independently of other variables (age, sex, and genotype).

Conclusions

Our data establish relationships between resistin levels in the plasma and sputum of CF patients that correlate with disease status, and identify resistin as a novel mechanistic link between neutrophilic inflammation and lung disease in CF.  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