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   25971篇
  免费   1402篇
  国内免费   148篇
耳鼻咽喉   273篇
儿科学   550篇
妇产科学   621篇
基础医学   3331篇
口腔科学   1029篇
临床医学   1874篇
内科学   6925篇
皮肤病学   695篇
神经病学   1970篇
特种医学   492篇
外科学   4293篇
综合类   171篇
一般理论   3篇
预防医学   1858篇
眼科学   437篇
药学   1428篇
中国医学   118篇
肿瘤学   1453篇
  2023年   188篇
  2022年   153篇
  2021年   841篇
  2020年   439篇
  2019年   889篇
  2018年   1024篇
  2017年   572篇
  2016年   585篇
  2015年   753篇
  2014年   1098篇
  2013年   1379篇
  2012年   2182篇
  2011年   2232篇
  2010年   1316篇
  2009年   1141篇
  2008年   1801篇
  2007年   1858篇
  2006年   1706篇
  2005年   1521篇
  2004年   1409篇
  2003年   1338篇
  2002年   1229篇
  2001年   144篇
  2000年   117篇
  1999年   154篇
  1998年   146篇
  1997年   125篇
  1996年   107篇
  1995年   122篇
  1994年   95篇
  1993年   82篇
  1992年   70篇
  1991年   51篇
  1990年   49篇
  1989年   36篇
  1988年   42篇
  1987年   32篇
  1986年   20篇
  1985年   37篇
  1984年   35篇
  1983年   38篇
  1982年   43篇
  1981年   42篇
  1980年   41篇
  1979年   17篇
  1978年   23篇
  1977年   25篇
  1975年   22篇
  1974年   21篇
  1973年   18篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
This paper examines the propagation of COVID-19 across the Spanish provinces and assesses the effectiveness of the Spanish lockdown of the population implemented on March 14, 2020 in order to battle this pandemic. To achieve these objectives, a standard spatial econometric model used in economics is adapted to resemble the popular reproduction models employed in the epidemiological literature. In addition, we introduce a counterfactual exercise that allows us to examine the Gross domestic product (GDP) gains of bringing forward the date of the Spanish Lockdown. We find that the number of COVID-19 cases would have been reduced by 70.4% in the absence of spatial propagation between the Spanish provinces. We also determine that the lockdown prevented the propagation of the virus within and between provinces. As such, the Spanish lockdown reduced the number of potential COVID-19 cases by 82.8%. However, the number of coronavirus cases would have been reduced by an additional 11.6% if the lockdown had been brought forward to March 7, 2020. Finally, an earlier lockdown would have saved approximately 26,900,000,000 euros.  相似文献   
2.
3.
The mechanisms linking tumor microenvironment acidosis to disease progression are not understood. Here, we used mammary, pancreatic, and colon cancer cells to show that adaptation to growth at an extracellular pH (pHe) mimicking acidic tumor niches is associated with upregulated net acid extrusion capacity and elevated intracellular pH at physiological pHe, but not at acidic pHe. Using metabolic profiling, shotgun lipidomics, imaging and biochemical analyses, we show that the acid adaptation-induced phenotype is characterized by a shift toward oxidative metabolism, increased lipid droplet-, triacylglycerol-, peroxisome content and mitochondrial hyperfusion. Peroxisome proliferator-activated receptor-α (PPARA, PPARα) expression and activity are upregulated, at least in part by increased fatty acid uptake. PPARα upregulates genes driving increased mitochondrial and peroxisomal mass and β-oxidation capacity, including mitochondrial lipid import proteins CPT1A, CPT2 and SLC25A20, electron transport chain components, peroxisomal proteins PEX11A and ACOX1, and thioredoxin-interacting protein (TXNIP), a negative regulator of glycolysis. This endows acid-adapted cancer cells with increased capacity for utilizing fatty acids for metabolic needs, while limiting glycolysis. As a consequence, the acid-adapted cells exhibit increased sensitivity to PPARα inhibition. We conclude that PPARα is a key upstream regulator of metabolic changes favoring cancer cell survival in acidic tumor niches.  相似文献   
4.
Data about treatment outcomes and toxicity in Latin America are scarce. There are differences with central countries based on access to healthcare system and socioeconomic status. Argentinean Society of Hematology recommends bortezomib-based triplets for induction treatment of transplant eligible newly diagnosed multiple myeloma patients. Most common options are CyBorD (cyclophosphamide, bortezomib and dexamethasone) and VTD (bortezomib, thalidomide and dexamethasone). Main goal of our retrospective, multicentric study was to compare very good partial response rate (VGPR) or better after induction treatment in a real-world setting in Argentina. Secondary objectives included comparison of complete response (CR) post-induction and after bone marrow transplantation, grade 3-4 adverse events (AEs), progression-free survival (PFS) and overall survival (OS). Three hundred twenty-two patients were included (median age at diagnosis: 57 years; 52% male; 28% had ISS3; 14% with high-risk cytogenetics; median follow up: 34 months). CyBorD was indicated in 74% and 26% received VTD. In VTD arm, 72.62% of patients achieved at least VGPR vs 53.36% receiving CyBorD (odds ratio, OR: 1.96 [95% confidence interval, CI: 1.08-3.57; P = .026] after adjusting by age, ISS [International Staging System], lactate dehydrogenase levels (LDH) and cytogenetic risk. Difference in VGPR was 19.26% (95% CI: 15-24). CR rate were 35.92% (VTD) vs 22.55% (CyBorD) (adjusted OR: 2.13 [95% CI: 1.12-4.05]). Difference in CR was 13.37% (95% CI: 9.6-17.53). Adverse events (AEs) were more common with VTD (69.05% vs 55.46% for CyBorD; P = .030), especially grade 3-4 neuropathy (P = .005) and thrombosis (P = .001). Thromboprophylaxis was inadequate in 20.24% of patients. Hematological AEs were more common with CyBorD, especially thrombocytopenia (P = .017). PFS and OS at 24 months were not different between treatments. In this real-world setting, VTD was associated with better CR and VGPR than CyBorD. Nevertheless, CyBorD continues to be the preferred induction regimen in Argentina, based on safety profile. Frontline autologous stem cell transplantation improves quality of responses, especially in countries with limited access to new drugs.  相似文献   
5.
Lionfish is an invasive and predatory species with low local consumption due to a lack of culinary knowledge of its preparation. A new way to prepare lionfish was proposed to increase variety and provide added value. The aim of this study was to evaluate the effect of high power ultrasound application on the textural properties measured by the texture profile analysis, sensory attributes, and shape preference of surimi patties (rounded and square) made from lionfish. Patties were prepared using lionfish surimi processed with ultrasound (37 kHz; 150 W), sodium citrate (0.3%), sucrose (1%), and salt (2%). Ultrasound exposure increased the hardness of the patties by 35.1%, decreased cohesiveness by 89.7%, and decreased the chewiness by 49.1%. Results show that high power ultrasound showed potential as an environmentally friendly technology to create surimi as a base for patties with sensory and textural appropriateness, increasing the potential culinary applications of lionfish.  相似文献   
6.
Since the first report in 1954, abdominal pseudocysts have been recognized as a particularly uncommon complication of ventriculoperitoneal shunts of CSF, so their etiology, diagnosis, and therapeutic management remain very controversial.Our objective is to offer a critical and updated systematic review of those controversial points, using a thorough search and review of the most relevant literature available.The clinical presentation of pseudocysts is normally through non-specific abdominal symptoms. The most validated etiology consists on the existence of a concomitant infection of the CSF shunt system, and so, treatment needs of antibiotherapy and total or partial substitution of the system. However, the pseudocyst itself doesn’t need an active treatment, except for some specific cases. This management, algorithmically presented in the present work, achieves a lower recurrence rate than other options, but this one is still important, and is also associated with other complications of those shunts related with several other factors which need to be taken in account.  相似文献   
7.

Background

The Parkland Grading Scale for Cholecystitis (PGS) was developed as an intraoperative grading scale to stratify gallbladder (GB) disease severity during laparoscopic cholecystectomy (LC). We aimed to prospectively validate this scale as a measure of LC outcomes.

Methods

Eleven surgeons took pictures of and prospectively graded the initial view of 317?GBs using PGS while performing LC (LIVE) between 9/2016 and 3/2017. Three independent surgeon raters retrospectively graded these saved GB images (STORED). The Intraclass Correlation Coefficient (ICC) statistic assessed rater reliability. Fisher's Exact, Jonckheere-Terpstra, or ANOVA tested association between peri-operative data and gallbladder grade.

Results

ICC between LIVE and STORED PGS grades demonstrated excellent reliability (ICC?=?0.8210). Diagnosis of acute cholecystitis, difficulty of surgery, incidence of partial and open cholecystectomy rates, pre-op WBC, length of operation, and bile leak rates all significantly increased with increasing grade.

Conclusions

PGS is a highly reliable, simple, operative based scale that can accurately predict outcomes after LC.

Table of contents summary

The Parkland Grading Scale for Cholecystitis was found to be a reliable and accurate predictor of laparoscopic cholecystectomy outcomes. Diagnosis of acute cholecystitis, surgical difficulty, incidence of partial and open cholecystectomy rates, pre-op WBC, operation length, and bile leak rates all significantly increased with increasing grade.  相似文献   
8.
BackgroundPatients undergoing pancreatic resection frequently require rehabilitation facilities after hospital discharge. We evaluated the predictive role of validated markers of frailty on rehabilitation facility placement to identify patients who may require this service.MethodsSingle-center retrospective cohort study of patients who underwent pancreatic resection from 2010 to 2015. 90-day morbidity and mortality were calculated. Postoperative validated markers of frailty (Activities of Daily Living scale, Braden scale [assesses pressure ulcer risk, lower scores = higher risk] and Morse fall scale) were evaluated via multivariate regression to identify predictors of discharge to rehabilitation facility.Results470 patients with complete data were included. Mean age was 62 and 49.2% were male. Postoperative median length of stay (LOS) was 8 (IQR 7–10). 92 (19.66%) patients were discharged to rehabilitation facilities and 138 (29.49%) patients were readmitted within 90 days. On multivariate analysis, age, sex, LOS > 8 days, inpatient Comprehensive Complication Index (CCI) and initial Braden scale were predictive of rehabilitation placement.ConclusionA marker of frailty routinely collected daily by nursing staff, the Braden scale, is available to help surgeons predict the need for postoperative rehabilitation placement after pancreatic resection. Engaging discharge planning services for at-risk patients may help prevent delayed hospital discharge and should be further evaluated.  相似文献   
9.
The epidemiological cycle of zoonotic phlebotomine‐borne Leishmania infantum is a complex system in which domestic animals and wildlife interact and participate in its maintenance and transmission. In this study, we combined entomological surveillance, xenomonitoring of L. infantum and identification of host feeding sources of engorged females to investigate the potential contribution of a periurban wildlife park to leishmaniosis in neighbouring residential areas. Overall, 7,309 sand flies were collected in 111 trap‐days during the summers of 2016–2018 in an endemic area in south‐east Spain. Five different sand fly species were captured, with Phlebotomus perniciosus, the main L. infantum vector in this region, representing the most common species. Sand fly distribution was spatially heterogeneous in terms of species, sexes and female physiological stage (unfed, gravid and engorged females) and related to host distribution and management, and environmental features. None of the 602 sand flies analysed for L. infantum infection by kinetoplast real‐time PCR were positive. We used molecular tools to identify the vertebrate hosts of sand flies and identified 17 host species, mainly mammals. Human DNA was not identified in engorged sand flies. This study provides evidence that wildlife parks in south‐east Spain are ideal grounds for sand fly vectors but do not necessarily increase L. infantum infection risk to humans and dogs living in surrounding residential areas. This is probably because vectors feed mostly on non‐L. infantum competent hosts and this should be investigated for a better understanding of the contribution of wildlife parks to the local epidemiology of L. infantum.  相似文献   
10.
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