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   5983篇
  免费   353篇
  国内免费   18篇
耳鼻咽喉   68篇
儿科学   194篇
妇产科学   292篇
基础医学   808篇
口腔科学   130篇
临床医学   484篇
内科学   1158篇
皮肤病学   128篇
神经病学   521篇
特种医学   153篇
外科学   873篇
综合类   99篇
一般理论   4篇
预防医学   559篇
眼科学   159篇
药学   350篇
中国医学   16篇
肿瘤学   358篇
  2023年   45篇
  2022年   81篇
  2021年   217篇
  2020年   103篇
  2019年   157篇
  2018年   184篇
  2017年   119篇
  2016年   142篇
  2015年   164篇
  2014年   210篇
  2013年   273篇
  2012年   416篇
  2011年   404篇
  2010年   209篇
  2009年   175篇
  2008年   331篇
  2007年   312篇
  2006年   312篇
  2005年   289篇
  2004年   271篇
  2003年   232篇
  2002年   233篇
  2001年   69篇
  2000年   81篇
  1999年   69篇
  1998年   63篇
  1997年   54篇
  1996年   34篇
  1995年   35篇
  1994年   43篇
  1993年   38篇
  1992年   54篇
  1991年   53篇
  1990年   44篇
  1989年   51篇
  1988年   52篇
  1987年   48篇
  1986年   53篇
  1985年   36篇
  1984年   25篇
  1983年   30篇
  1982年   29篇
  1981年   27篇
  1980年   26篇
  1979年   43篇
  1978年   26篇
  1975年   23篇
  1974年   32篇
  1973年   23篇
  1971年   26篇
排序方式: 共有6354条查询结果,搜索用时 47 毫秒
61.
62.
Strict isolation of vulnerable individuals has been a strategy implemented by authorities to protect people from COVID-19. Our objective was to investigate health-related quality of life (HRQoL), uncertainty and coping behaviours in solid organ transplant (SOT) recipients during the COVID-19 pandemic. A cross-sectional survey of adult SOT recipients undergoing follow-up at our institution was performed. Perceived health status, uncertainty and coping strategies were assessed using the EQ-5D-5L, Short-form Mishel Uncertainty in Illness Scale (SF-MUIS) and Brief Cope, respectively. Interactions with COVID-19 risk perception, access to health care, demographic and clinical variables were assessed. The survey was completed by 826 of 3839 (21.5%) invited participants. Overall, low levels of uncertainty in illness were reported, and acceptance was the major coping strategy (92%). Coping by acceptance, feeling protected, self-perceived susceptibility to COVID-19 were associated with lower levels of uncertainty. Health status index scores were significantly lower for those with mental health illness, compromised access to health care, a perceived high risk of severe COVID-19 infection and higher levels of uncertainty. A history of mental health illness, risk perceptions, restricted healthcare access, uncertainty and coping strategies was associated with poorer HRQoL in SOT recipients during strict isolation. These findings may allow identification of strategies to improve HRQoL in SOT recipients during the pandemic.  相似文献   
63.
Enhanced Recovery After Surgery (ERAS) constitutes the application of a series of perioperative measures based on the evidence, in order to achieve a better recovery of the patient and a decrease of the complications and the mortality. These ERAS programs initially proved their advantages in the field of colorectal surgery being progressively adopted by other surgical areas within the general surgery and other surgical specialties. The main excluding factor for the application of such programs has been the urgent clinical presentation, which has caused that despite the large volume of existing literature on ERAS in elective surgery, there are few studies that have investigated the effectiveness of these programs in surgical patients in emergencies. The aim of this article is to show ERAS measures currently available according to the existing evidence for emergency surgery.  相似文献   
64.
Type 1 diabetes is an autoimmune disease resulting in severely impaired insulin secretion. We investigated whether circulating microRNAs (miRNAs) are associated with residual insulin secretion at diagnosis and predict the severity of its future decline. We studied 53 newly diagnosed subjects enrolled in placebo groups of TrialNet clinical trials. We measured serum levels of 2,083 miRNAs, using RNA sequencing technology, in fasting samples from the baseline visit (<100 days from diagnosis), during which residual insulin secretion was measured with a mixed meal tolerance test (MMTT). Area under the curve (AUC) C-peptide and peak C-peptide were stratified by quartiles of expression of 31 miRNAs. After adjustment for baseline C-peptide, age, BMI, and sex, baseline levels of miR-3187-3p, miR-4302, and the miRNA combination of miR-3187-3p/miR-103a-3p predicted differences in MMTT C-peptide AUC/peak levels at the 12-month visit; the combination miR-3187-3p/miR-4723-5p predicted proportions of subjects above/below the 200 pmol/L clinical trial eligibility threshold at the 12-month visit. Thus, miRNA assessment at baseline identifies associations with C-peptide and stratifies subjects for future severity of C-peptide loss after 1 year. We suggest that miRNAs may be useful in predicting future C-peptide decline for improved subject stratification in clinical trials.  相似文献   
65.
66.
Pro-inflammatory cytokine and chemokines genes drive prostate cancer progression and metastasis: molecular mechanism update and the science that underlies racial disparity. comprehensive review article.Isaac J. Powell, S. Chinni, S.S. Reddy, Alexander Zaslavsky, Navnath Gavande Introduction: In 2013 we reported that with the use of bioinformatics and ingenuity pathway network analysis we were able to identify functional driver genes that were differentially expressed among a large population of African American men (AAM) and European American men (EAM). Pro-inflammatory cytokine genes were found to be more interactive and more expressed among AAM and have been found to be functional drivers of aggressive prostate cancer (CaP) and aggressiveness in other solid tumors. We examined these genes and biological pathways initiated by these cytokines in primary CaP tissue.Method We unravel the gene network and identified biologic pathways that impacted activation of the androgen receptor, mesenchymal epithelial transition (invasion) and chemokines associated with metastasis in the CaP tissue from 639 radical prostatectomy specimens.Results Biologic pathways identified by unraveling pro-inflammatory genes from our network, more expressed among AAM compared to EAM, were tumor necrosis factor (TNF), IL1b, IL6, and IL8. IL6 and IL8 are downstream of TNF activity and are known activators of androgen receptor and through mediators promote CaP cell proliferation. TNF and IL1b mediate tumor cell invasiveness through the activation of MMP (matrix metalloproteinase) which down regulates E-Cadherin to initiate epithelial mesenchymal transition which allows cells to become invasive in the microenvironment. Ultimately our network analysis indicates that TNF and IL1b activate CXCR4 receptor on CaP cells, which facilitates metastatic progression reportedly by binding to CXCL12 on lipid rafts and tumor implantation in the bone marrow.Conclusion Our retrospective biologic mechanistic model reveals a set of pro-inflammatory cytokines and chemokines that drive CaP aggressiveness, tumor heterogeneity, progression and metastasis. A prospective multi-institutional study needs to be conducted for clinical validation as well consideration of targeted therapy.  相似文献   
67.
Background

The ongoing Boko Haram insurgency in northeastern Nigeria has depleted the country’s capability to deliver quality healthcare to her citizenry. The ailing health sector is overwhelmed with a rising incidence and prevalence of infectious and non-communicable diseases.

Aim

The aim of this paper was to determine the trend of kidney disease, end-stage renal disease (ESRD), anaemia, malnutrition and human immunodeficiency virus (HIV) in northeastern Nigeria.

Materials and methods

Data covering different periods between 1999 and 2017 were obtained from the University of Maiduguri Teaching Hospital (UMTH), Maiduguri in northeastern Nigeria. This hospital is the largest tertiary healthcare facility in the region. The data were demographic in nature, i.e. sex, age or simply the registered cases. A quadratic model of time-series analysis was used to create the various trends of the respective diseases with the aid of Minitab software (version 18.0). t-Tests and analysis of variance (ANOVA) were also performed, with a p-value of less than or equal to 0.05 being considered significant.

Results

About three out of every five patients treated for kidney disease were male, while three out of every five patients treated for HIV were female. Patients between the ages of 31 and 50 years were at the greatest risk of developing kidney disease. The mean distribution of disease incidence was the same for both sexes for kidney disease, anaemia, malnutrition and HIV. The mean distribution disease incidence was different between age groups for kidney disease but the same for anaemia. The incidence of anaemia and malnutrition reported was almost the same for both sexes. Children under the age of 10 years old were at the most risk of anaemia, with the distribution decreasing with increasing age. The trend analysis of the incidence of kidney disease, ESRD, anaemia and malnutrition showed that these ailments were on the increase, while the number of patients that were on antiretroviral therapy (ART) was on the decline in northeastern Nigeria.

Conclusion

These increasing trends are evidences of the effect of Boko Haram on the public health of the people of northeastern Nigeria and will continue to be a public health concern for the region and the country as a whole.

  相似文献   
68.
The COVID‐19 pandemic continues to be a major public health threat globally and low‐ and middle‐income countries (LMICs) are not an exception. The impact of the COVID‐19 pandemic is far‐reaching on many areas including but not limited to global health security, economic and healthcare delivery with a potential impact on access to healthcare in LMICs. We evaluate the impact of the COVID‐19 pandemic on access to healthcare in LMICs, as well as plausible strategies that can be put in place to ensure that the delivery of healthcare is not halted. In order to mitigate the devastating effect of the COVID‐19 pandemic on the already weak health systems in LMICs, it is much necessary to reinforce and scale up interventions and proactive measures that will ensure that access to healthcare is not disrupted even in course of the pandemic.  相似文献   
69.
This report investigates the sequence specificity requirements for homeodomain structure and DNA binding activity by the design and synthesis of a "minimAl" homeodomain (for minimalist design and alanine scanning mutagenesis) which contains the consensus residues and in which all nonconsensus residues have been replaced with alanine. The murine homeodomain Msx served as the prototype for the minimAl homeodomain, Ala-Msx. We show that Ala-Msx binds to DNA specifically, albeit with lower affinity than Msx. A derivative of the minimAl homeodomain, Ala-Msx(NT), which contains a native rather than an alanine-substituted N-terminal arm, has similar DNA binding affinity as Msx. We show that the native N-terminal arm stabilizes the tertiary structure of the minimAl homeodomain. Although Ala-Msx resembles a molten-globule protein, the structure of Ala-Msx(NT) is similar to Msx. The requirement for an intact N-terminal arm is not unique to the minimAl homeodomain, since the N-terminal arm also promotes high-affinity binding activity and appropriate tertiary structure of Msx. Therefore, the homeodomain "scaffold" consists of consensus residues, which are sufficient for DNA recognition, and nonconsensus residues in the N-terminal arm, which are required for optimal DNA binding affinity and appropriate tertiary structure. MinimAl design provides a powerful strategy to probe homeodomain structure and function. This approach should be of general utility to study the sequence specificity requirements for structure and function of other DNA-binding domains.  相似文献   
70.
BACKGROUND: Conventional cardiopulmonary resuscitation (CPR) includes 80-100/min precordial compressions with intermittent positive pressure ventilation (IPPV) after every fifth compression. To prevent gastric insufflation, chest compressions are held during IPPV if the patient is not intubated. Elimination of IPPV would simplify CPR and might offer physiologic advantages, but compression-induced ventilation without IPPV has been shown to result in hypercapnia. The authors hypothesized that application of continuous positive airway pressure (CPAP) might increase CO2 elimination during chest compressions. METHODS: After appropriate instrumentation and measurement of baseline data, ventricular fibrillation was induced in 18 pigs. Conventional CPR was performed as a control (CPR(C)) for 5 min. Pauses were then discontinued, and animals were assigned randomly to receive alternate trials of uninterrupted chest compressions at a rate of 80/min without IPPV, either at atmospheric airway pressure (CPR(ATM)) or with CPAP (CPR(CPAP)). CPAP was adjusted to produce a minute ventilation of 75% of the animal's baseline ventilation. Data were summarized as mean +/- SD and compared with Student t test for paired observations. RESULTS: During CPR without IPPV, CPAP decreased PaCO2 (55+/-28 vs. 100+/-16 mmHg) and increased SaO2 (0.86+/-0.19 vs. 0.50+/-0.18%; P < 0.001). CPAP also increased arteriovenous oxygen content difference (10.7+/-3.1 vs. 5.5+/-2.3 ml/dl blood) and CO2 elimination (120+/-20 vs. 12+/-20 ml/min; P < 0.01). Differences between CPR(CPAP) and CPR(ATM) in aortic blood pressure, cardiac output, and stroke volume were not significant. CONCLUSIONS: Mechanical ventilation may not be necessary during CPR as long as CPAP is applied. Discontinuation of IPPV will simplify CPR and may offer physiologic advantage.  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