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   6803篇
  免费   507篇
  国内免费   26篇
耳鼻咽喉   218篇
儿科学   206篇
妇产科学   189篇
基础医学   877篇
口腔科学   201篇
临床医学   557篇
内科学   1497篇
皮肤病学   126篇
神经病学   330篇
特种医学   261篇
外国民族医学   1篇
外科学   1009篇
综合类   153篇
一般理论   13篇
预防医学   403篇
眼科学   124篇
药学   608篇
  1篇
中国医学   47篇
肿瘤学   515篇
  2024年   12篇
  2023年   76篇
  2022年   235篇
  2021年   305篇
  2020年   185篇
  2019年   256篇
  2018年   272篇
  2017年   188篇
  2016年   226篇
  2015年   244篇
  2014年   323篇
  2013年   390篇
  2012年   533篇
  2011年   540篇
  2010年   284篇
  2009年   197篇
  2008年   344篇
  2007年   326篇
  2006年   302篇
  2005年   243篇
  2004年   237篇
  2003年   251篇
  2002年   198篇
  2001年   135篇
  2000年   133篇
  1999年   110篇
  1998年   45篇
  1997年   26篇
  1996年   27篇
  1995年   28篇
  1994年   34篇
  1993年   23篇
  1992年   46篇
  1991年   45篇
  1990年   54篇
  1989年   40篇
  1988年   40篇
  1987年   37篇
  1986年   35篇
  1985年   35篇
  1984年   25篇
  1983年   27篇
  1982年   27篇
  1981年   12篇
  1979年   18篇
  1978年   21篇
  1977年   17篇
  1976年   20篇
  1974年   14篇
  1973年   17篇
排序方式: 共有7336条查询结果,搜索用时 15 毫秒
101.
Fatal Ruptured Duodenal Varix: A Case Report and Review of Literature   总被引:2,自引:0,他引:2  
The incidence of bleeding duodenal varices is exceedingly rare. We report a case of a 35-year-old chronic alcoholic who died of severe fatal upper gastrointestinal bleeding from a ruptured duodenal varix located in the second portion of duodenum. This diagnosis was suspected at endoscopy and was confirmed at autopsy. A review of literature shows 20 case reports of bleeding duodenal varices with two fatalities. While the duodenal bulb is the most common site of varices, the second portion of duodenum appears to be the next most common site. From all of the possible causes of duodenal varix, chronic liver diseases, mainly cirrhosis, remains the predominant etiological factor accounting for 30.7% of reported cases.  相似文献   
102.
103.
104.
105.

Introduction:

Causes of death are different and very important for policy makers in different regions. This study was designed to analyze the data for our in-patient children mortality.

Materials and Methods:

In this cross-sectional study from March 2011 to March 2013, all patients from 2 months to 18 years who died in pediatric intensive care unit, emergency room or medical pediatric wards in the teaching hospitals were studied.

Results:

From a total of 18,915 admissions during a 2-year-period, 256 deaths occurred with a mean age of 4.3 ± 5 years and mortality 1.35%. An underlying disease was present in 70.7% of the patients and in 88.5% of them the leading causes of death were related to the underlying diseases. The most common underlying diseases were congenital heart disease and cardiomyopathy in 50 (27.6%). The four main causes of deaths were sepsis (14.8%), pneumonia (14.5%), congestive heart failure (9.8%), and hepatic encephalopathy (9.8%).

Conclusion:

We may conclude that after sepsis and pneumonia, congestive heart failure, and hepatic encephalopathy are the leading causes of death. Most patients who died had underlying diseases including malignancies, heart and liver diseases as the most common causes.  相似文献   
106.
The aim of our study is to investigate whether single-nucleotide dystrophin gene (DMD) variants associate with variability in cognitive functions in healthy populations. The study included 1240 participants from the Erasmus Rucphen family (ERF) study and 1464 individuals from the Rotterdam Study (RS). The participants whose exomes were sequenced and who were assessed for various cognitive traits were included in the analysis. To determine the association between DMD variants and cognitive ability, linear (mixed) modeling with adjustment for age, sex and education was used. Moreover, Sequence Kernel Association Test (SKAT) was used to test the overall association of the rare genetic variants present in the DMD with cognitive traits. Although no DMD variant surpassed the prespecified significance threshold (P<1 × 10−4), rs147546024:A>G showed strong association (β=1.786, P-value=2.56 × 10−4) with block-design test in the ERF study, while another variant rs1800273:G>A showed suggestive association (β=−0.465, P-value=0.002) with Mini-Mental State Examination test in the RS. Both variants are highly conserved, although rs147546024:A>G is an intronic variant, whereas rs1800273:G>A is a missense variant in the DMD which has a predicted damaging effect on the protein. Further gene-based analysis of DMD revealed suggestive association (P-values=0.087 and 0.074) with general cognitive ability in both cohorts. In conclusion, both single variant and gene-based analyses suggest the existence of variants in the DMD which may affect cognitive functioning in the general populations.  相似文献   
107.
Receptor recycling plays a critical role in the regulation of cellular responsiveness to environmental stimuli. Agonist-promoted phosphorylation of G protein-coupled receptors has been related to their desensitization, internalization, and sequestration. Dephosphorylation of internalized G protein-coupled receptors by cytoplasmic phosphatases has been shown to be pH-dependent, and it has been postulated to be necessary for receptors to recycle to the cell surface. The internalized V2 vasopressin receptor (V2R) expressed in HEK 293 cells is an exception to this hypothesis because it does not recycle to the plasma membrane for hours after removal of the ligand. Because this receptor is phosphorylated only by G protein-coupled receptor kinases (GRKs), the relationship between recycling and GRK-mediated phosphorylation was examined. A nonphosphorylated V2R, truncated upstream of the GRK phosphorylation sites, rapidly returned to the cell surface after removal of vasopressin. Less-drastic truncations of V2R revealed the presence of multiple phosphorylation sites and suggested a key role for a serine cluster present at the C terminus. Replacement of any one of Ser-362, Ser-363, or Ser-364 with Ala allowed quantitative recycling of full-length V2R without affecting the extent of internalization. Examination of the stability of phosphate groups incorporated into the recycling S363A mutant V2Rs revealed that the recycling receptor was dephosphorylated after hormone withdrawal, whereas the wild-type V2R was not, providing molecular evidence for the hypothesis that GRK sites must be dephosphorylated prior to receptor recycling. These experiments uncovered a role for GRK phosphorylation in intracellular sorting and revealed a GRK-dependent anchoring domain that blocks V2R recycling.  相似文献   
108.

Objective

To assess the effect of race on the incidence of aortic stenosis (AS) and utilization and outcomes of aortic valve replacement (AVR).

Patients and Methods

Patients older than 60 years hospitalized with a primary diagnosis of AS and those who underwent AVR between 2003 and 2014 were included. Adjusted and unadjusted incidence of AS-related hospitalizations, utilization rates of AVR, in-hospital morbidity and mortality, and resource utilization was compared between whites and African Americans (AAs).

Results

Between January 1, 2003, and December 31, 2014, the incidence of AS-related admissions increased from 13 (95% CI, 12.8-13.2) to 26 (95% CI, 25.7-26.4) cases per 100,000 patient-years in whites and from 3 (95% CI, 3.5-3.8) to 9.5 (95% CI, 9.4-9.8) cases per 100,000 patient-years in AAs (P<.001). The incidence density ratio decreased from 4.3 (95% CI, 2.27-6.6) in 2003 to 2.7 (95% CI, 1.1-3.8) in 2014. The ratio of AVR to AS-related admissions was 11.3% in whites and 6.7% in AAs (P<.001). Crude in-hospital mortality after AVR was higher in AAs (6.4% vs 4.7%; P<.001). However, after propensity score matching, in-hospital morality after isolated AVR was not significantly different between AAs and whites (4.7% vs 3.7%; P=.12). African Americans also had longer hospitalizations (12±12 days vs 10±9 days; P<.001), higher rates of nonhome discharge (32.1% vs 27.2%; P=.004), and higher cost of hospitalization ($55,631±$37,773 vs $52,521±$38,040; P<.001).

Conclusions

African Americans undergo AVR less than whites. The underlying etiology of this disparity is multifactorial, but may be related to a lower incidence of AS in AAs. Aortic valve replacement is associated with similar risk-adjusted in-hospital mortality but higher cost and longer hospitalizations in AAs than in whites.  相似文献   
109.

Objective

To review the literature and assess the comparative effectiveness of ultrasound-guided versus landmark-guided local corticosteroid injections in patients with carpal tunnel syndrome (CTS).

Data Sources

Cochrane Central Register of Controlled Trials, MEDLINE (PubMed), Embase (Ovid), and Web of Science (from inception to February 1, 2017).

Study Selection

Randomized controlled trials (RCTs) comparing ultrasound-guided injection with landmark-guided injection in patients with CTS were included.

Data Extraction

Two authors independently screened abstracts and full texts. The outcomes of interest were Symptom Severity Scale (SSS) and Functional Status Scale (FSS) scores of the Boston Carpal Tunnel Questionnaire and 4 electrodiagnostic parameters, including compound muscle action potential (CMAP), sensory nerve action potential (SNAP), distal motor latency (DML), and distal sensory latency (DSL).

Data Synthesis

Overall, 569 abstracts were retrieved and checked for eligibility; finally, 3 RCTs were included (181 injected hands). Pooled analysis showed that ultrasound-guided injection was more effective in SSS improvement (mean difference [MD], ?.46; 95% confidence interval [CI], ?.59 to ?.32; P<.00001), whereas no significant difference was observed between the 2 methods in terms of the FSS (MD, ?.25; 95% CI, ?.56 to .05; P=.10). There were also no statistically significant differences in improvements of CMAP (MD, 1.54; 95% CI, 0.01 to 3.07; P=.05), SNAP (MD, ?0.02; 95% CI, ?6.27 to 6.23; P>.99), DML (MD, .05; 95% CI, ?.30 to .39; P=.80), or DSL (MD, .00; 95% CI, ?.65 to .65; P>.99).

Conclusions

This review suggested that ultrasound-guided injection was more effective than landmark-guided injection in symptom severity improvement in patients with CTS; however, no significant differences were observed in functional status or electrodiagnostic improvements between the 2 methods.  相似文献   
110.

Background

The placement of a central venous catheter for the administration of vasopressors is still recommended and required by many institutions because of concern about complications associated with peripheral administration of vasopressors.

Objective

Our aim was to determine the incidence of complications from the administration of vasopressors through peripheral venous catheters (PVC) in patients with circulatory shock, and to identify the factors associated with these complications.

Methods

This was a prospective, observational study conducted in the emergency department (ED) of a tertiary care medical center. Patients presenting to the ED with circulatory shock and in whom a vasopressor was started through a PVC were included. Research fellows examined the i.v. access site for complications twice daily during the period of peripheral vasopressor administration, then daily up to 48 h after treatment discontinuation or until the patient expired.

Results

Of the 55 patients that were recruited, 3 (5.45% overall, 6% of patients receiving norepinephrine) developed complications; none were major. Two developed local extravasation and one developed local thrombophlebitis. All three complications occurred during the vasopressor infusion, none in the 48 h after discontinuation, and none required any medical or surgical intervention. Two of the three complications occurred in the hand, and all occurred in patients receiving norepinephrine and with 20-gauge catheters.

Conclusions

The incidence of complications from the administration of vasopressors through a PVC is small and did not result in significant morbidity in this study. Larger prospective studies are needed to better determine the factors that are associated with these complications, and identify patients in whom this practice is safe.  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