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   8106篇
  免费   584篇
  国内免费   36篇
耳鼻咽喉   76篇
儿科学   238篇
妇产科学   235篇
基础医学   1187篇
口腔科学   140篇
临床医学   871篇
内科学   1714篇
皮肤病学   207篇
神经病学   763篇
特种医学   175篇
外科学   702篇
综合类   74篇
一般理论   9篇
预防医学   940篇
眼科学   160篇
药学   649篇
中国医学   19篇
肿瘤学   567篇
  2024年   12篇
  2023年   85篇
  2022年   159篇
  2021年   311篇
  2020年   190篇
  2019年   262篇
  2018年   293篇
  2017年   186篇
  2016年   244篇
  2015年   269篇
  2014年   334篇
  2013年   420篇
  2012年   683篇
  2011年   691篇
  2010年   400篇
  2009年   312篇
  2008年   536篇
  2007年   523篇
  2006年   508篇
  2005年   460篇
  2004年   383篇
  2003年   366篇
  2002年   339篇
  2001年   45篇
  2000年   40篇
  1999年   46篇
  1998年   61篇
  1997年   55篇
  1996年   33篇
  1995年   36篇
  1994年   33篇
  1993年   22篇
  1992年   25篇
  1991年   28篇
  1990年   16篇
  1989年   8篇
  1988年   17篇
  1987年   17篇
  1986年   18篇
  1985年   30篇
  1984年   18篇
  1983年   17篇
  1982年   18篇
  1981年   20篇
  1980年   22篇
  1979年   12篇
  1977年   8篇
  1974年   9篇
  1973年   12篇
  1928年   13篇
排序方式: 共有8726条查询结果,搜索用时 0 毫秒
71.
Obesity, type 2 diabetes, arterial hypertension, decrease in immune response, cytokine storm, endothelial dysfunction, and arrhythmias, which are frequent in COVID-19 patients, are associated with hypomagnesemia. Given that cellular influx and efflux of magnesium and calcium involve the same transporters, we aimed to evaluate the association of serum magnesium-to-calcium ratio with mortality from severe COVID-19. The clinical and laboratory data of 1064 patients, aged 60.3 ± 15.7 years, and hospitalized by COVID-19 from March 2020 to July 2021 were analyzed. The data of 554 (52%) patients discharged per death were compared with the data of 510 (48%) patients discharged per recovery. The ROC curve showed that the best cut-off point of the magnesium-to-calcium ratio for identifying individuals at high risk of mortality from COVID-19 was 0.20. The sensitivity and specificity were 83% and 24%. The adjusted multivariate regression model showed that the odds ratio between the magnesium-to-calcium ratio ≤0.20 and discharge per death from COVID-19 was 6.93 (95%CI 1.6–29.1) in the whole population, 4.93 (95%CI 1.4–19.1, p = 0.003) in men, and 3.93 (95%CI 1.6–9.3) in women. In conclusion, our results show that a magnesium-to-calcium ratio ≤0.20 is strongly associated with mortality in patients with severe COVID-19.  相似文献   
72.
73.
Butyrate, one of the major products of gut fermentation, is known to inhibit proliferation, induce apoptosis and differentiation, and increase phase II enzyme activities in tumor cells, whereas little information is available on protective effects in less-transformed colon cells. The aim of this study was to investigate whether the chemoprotective mechanism of glutathione S-transferase (GST) induction by butyrate could also play a role in earlier stages of colon carcinogenesis and whether chemoresistance of cells toward the endogenous genotoxic risk factor 4-hydroxy-2-nonenal (HNE) could be a consequence of butyrate treatment. As cell models, we used the human tumor cell lines HT29 and HT29 clone 19A, a differentiated subclone with properties resembling primary colon cells. We determined the expression of GSTP1 protein (enzyme-linked immunosorbent assay), the major GST in HT29, GSTP1 mRNA (Northern blotting), GST activity, intracellular glutathione, and total protein. The genotoxic impact of HNE (100-200 μM) was compared in butyrate-treated and nontreated cells using single-cell microgel electrophoresis. Our results show that GSTP1 mRNA, GSTP1 protein, GST activity, and total protein were increased (1.2- to 2.5-fold) and glutathione levels were maintained after 24- 72 h of incubation with 4 mM butyrate. Moreover, a marked reduction of HNE-induced genotoxicity was caused by preincubation with butyrate. Butyrate also induced the phosphorylation of extracellular signal-regulated kinases (ERK1/2, Western blotting) after 5-30 min, which indicates a regulation of GST expression by this signal pathway. Most effects were greater in HT29 parent cells than in clone cells. In conclusion, butyrate enhances expression of GST and other proteins in both cell lines, which leads to an enhanced chemoprotection, reducing the impact of HNE genotoxicity. Thus butyrate could play a role in early and later stages of cancer prevention by reducing exposure to relevant risk factors.  相似文献   
74.
75.
With the advent of new vaccines targeted to highly endemic diseases in low- and middle-income countries (LMIC) and with the expansion of vaccine manufacturing globally, there is an urgent need to establish an infrastructure to evaluate the benefit-risk profiles of vaccines in LMIC. Fortunately the usual decade(s)-long time gap between introduction of new vaccines in high and low income countries is being significantly reduced or eliminated due to initiatives such as the Global Alliance for Vaccines and Immunizations (GAVI) and the Decade of Vaccines for the implementation of the Global Vaccine Action Plan. While hoping for more rapid disease control, this time shift may potentially add risk, unless appropriate capacity for reliable and timely evaluation of vaccine benefit-risk profiles in some LMIC's are developed with external assistance from regional or global level. An ideal vaccine safety and effectiveness monitoring system should be flexible and sustainable, able to quickly detect possible vaccine-associated events, distinguish them from programmatic errors, reliably and quickly evaluate the suspected event and its association with vaccination and, if associated, determine the benefit-risk of vaccines to inform appropriate action. Based upon the demonstrated feasibility of active surveillance in LMIC as shown by the Burkina Faso assessment of meningococcal A conjugate vaccine or that of rotavirus vaccine in Mexico and Brazil, and upon the proof of concept international GBS study, we suggest a sustainable, flexible, affordable and timely international collaborative vaccine safety monitoring approach for vaccines being newly introduced. While this paper discusses only the vaccine component, the same system could also be eventually used for monitoring drug effectiveness (including the use of substandard drugs) and drug safety.  相似文献   
76.
Despite efforts to increase HIV testing in the African region, the proportion of men who report ever having been tested for HIV remains low. Research has focused on individual level determinants of women’s testing however little is known about factors associated with men’s testing behavior. This analysis investigates community influences on HIV testing among men ages 15–54, using Demographic and Health Survey (DHS) data from Chad, Ghana, Malawi, Nigeria, Tanzania, Uganda, Zambia, and Zimbabwe. Multilevel models were fitted in each country for the outcome of ever receiving an HIV test. After controlling for individual and household level factors, community level factors of demographics, economics, and behavior and knowledge remain significantly associated with HIV testing among men. The results of this analysis highlight the need to recognize the impact of community influences on men’s HIV test seeking behavior, and to harness these community factors in the design of programs aimed at encouraging the uptake of HIV testing among men in Africa.  相似文献   
77.
78.
79.
ObjetivoConocer las opiniones de los profesionales sanitarios que trabajan en el Punto de Atención Continuada de Ourense (PAC) con relación a las agresiones laborales.DiseñoEstudio cualitativo con enfoque fenomenológico realizado entre enero y mayo del 2019.EmplazamientoPAC.ParticipantesVeinte profesionales de distintas categorías.MédodoMuestreo estructural. Se emplearon entrevistas abiertas grabadas en audio, previo consentimiento de los participantes.ResultadosLos profesionales entrevistados manifiestas haber sido víctimas de agresiones, sobre todo verbales. Estas agresiones según los participantes son tan habituales que las han normalizado dentro de su jornada laboral. Ninguno ha denunciado nunca este tipo de conductas, en gran medida porque consideran que la burocracia y los trámites administrativos son tediosos, y otros por desconocimiento del procedimiento. Este tipo de situaciones, a nivel laboral, les causa sentimientos de tristeza, rabia e impotencia y son la causa, según ellos, del aumento de la medicina defensiva. Los profesionales consideran que la causa del aumento de las agresiones entre el colectivo es la mala educación y la gestión inadecuada del empoderamiento del paciente.ConclusionesLos profesionales sanitarios sufren continuamente agresiones, sobre todo de tipo verbal, siendo algo habitual en su día a día. Estas agresiones no son denunciadas, pero les causan múltiples sentimientos negativos y disruptivos, llegando a modificar su manera de trabajar.Palabras clave: Violencia laboral, Personal de salud, Agresión, Violencia  相似文献   
80.
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