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   1913篇
  免费   90篇
  国内免费   20篇
耳鼻咽喉   32篇
儿科学   43篇
妇产科学   68篇
基础医学   279篇
口腔科学   91篇
临床医学   126篇
内科学   483篇
皮肤病学   58篇
神经病学   123篇
特种医学   121篇
外科学   256篇
综合类   7篇
预防医学   90篇
眼科学   12篇
药学   134篇
中国医学   15篇
肿瘤学   85篇
  2023年   13篇
  2022年   20篇
  2021年   40篇
  2020年   30篇
  2019年   38篇
  2018年   57篇
  2017年   34篇
  2016年   37篇
  2015年   36篇
  2014年   60篇
  2013年   46篇
  2012年   107篇
  2011年   134篇
  2010年   60篇
  2009年   61篇
  2008年   78篇
  2007年   86篇
  2006年   78篇
  2005年   78篇
  2004年   90篇
  2003年   60篇
  2002年   58篇
  2001年   54篇
  2000年   53篇
  1999年   48篇
  1998年   33篇
  1997年   28篇
  1996年   25篇
  1995年   24篇
  1994年   23篇
  1993年   18篇
  1992年   26篇
  1991年   30篇
  1990年   30篇
  1989年   31篇
  1988年   37篇
  1987年   35篇
  1986年   24篇
  1985年   26篇
  1984年   17篇
  1983年   12篇
  1981年   11篇
  1979年   14篇
  1978年   8篇
  1974年   8篇
  1973年   8篇
  1968年   9篇
  1967年   8篇
  1966年   8篇
  1965年   10篇
排序方式: 共有2023条查询结果,搜索用时 15 毫秒
51.
Blood and plasma viscosity, as well as erythrocyte filtration rates were studied in 44 osteopenic (20 men and 24 women) and in 40 non-osteopenic (20 men and 20 women) patients, all over 65 years of age. Pathological hemorheological parameters were observed only in 12 subject of the osteopenic group, and 10 controls. The results indicate that although the hemorheological parameters do not show a direct correlation with the osteopenia, it is worthwhile following these parameters, among others, in order to optimize the treatment with anti-osteoporotic drugs which are able to regulate them.  相似文献   
52.
After the incorporation of automated external defibrillators by other airlines and the support of the Brazilian Society of Cardiology, Varig Airlines began the onboard defibrillation program with the initial purpose of equipping wide-body aircrafts frequently used in international flights and that airplanes use in the Rio - S?o Paulo route. With all flight attendants trained, the automated external defibrillation devices were incorporated to 34 airplanes of a total fleet of 80 aircrafts. The devices were installed in the baggage compartments secured with velcro straps and 2 pairs of electrodes, one or which pre-connected to the device to minimize application time. Later, a portable monitor was address to the resuscitation kit in the long flights. The expansion of the knowledge of the basic life support fundamentors and the corrected implantation of the survival chain and of the automated external defibrillators will increase the extense of recovery of cardiorespiratory arrest victims in aircrafts.  相似文献   
53.
The Heterobasidion annosum (Fr.) Bref. complex includes some of the most destructive conifer pathogenic fungi in the Boreal forest region. H. irregulare, formerly known as the North American pine type of H. annosum, was introduced from North America into Italy during the Second World War and occurs as an invasive pathogen in Pinus pinea stands together with the native European species H. annosum sensu stricto. We describe the complete nucleotide sequence of a new putative partitivirus from an Italian strain of H. irregulare. The bisegmented genome of HetRV8-ir1 encodes an RNA-dependent RNA polymerase of 704 aa and a capsid protein of 638 aa. The polymerase and capsid aa sequences are relatively similar (59-78 %) to those of Fusarium poae virus 1, Pleurotus ostreatus virus 1, and grapevine-associated partitivirus 1. HetRV8-ir1 is the first virus described from H. irregulare, and it is distantly related to previously known partitiviruses of Heterobasidion species.  相似文献   
54.
Journal of NeuroVirology - We describe two neurological cases of Oropouche virus infection in northern Brazil, where the virus is endemic but neglected as a pathogen. This study reiterates the...  相似文献   
55.
BackgroundStudies have grouped different overhead sports and evaluated together the isokinetic strength of shoulder internal (IR) and external (ER) rotator muscles. However, muscular adaptations could be a consequence of the specific sport, and some strength imbalance between these muscles may exist as a consequence of the muscular demand unique to the sport. Therefore, grouping different overhead sports together may not be adequate.PurposeTo compare strength balance ratios between different overhead sports (volleyball, handball, swimming, judo, baseball, softball, functional movements performed at high-intensity interval training, and tennis) with a control athletic group (no overhead group).Study designCross-sectional study.MethodsA total of 237 athletes were submitted to isokinetic shoulder strength tests. The isokinetic concentric and eccentric peak torque values of shoulder internal IR and external ER rotator muscles were measured. Conventional (CR) and functional strength ratios (FR) were calculated.ResultsThere were no significant differences between the sports for the CR in the male group. Female softball athletes (90.4±13.6%) had a significantly higher CR than judo (67.3±6.9%), volleyball (74.9±15.9%), and swimming athletes (70.3±8.7%). In the female group, judo athletes had lower FR values (0.76±0.19) than soccer athletes (1.31±0.35), volleyball athletes (1.24±0.27), functional movements performed at high intensity (1.10±0.1), and softball athletes (1.40±0.39). Female handball athletes also had a lower FR (0.99±0.25) than soccer athletes (1.31±0.35) and softball athletes (1.40±0.39). Male handball (0.90±0.23), tennis (0.86±0.30), and judo (0.68±0.22) athletes had lower FR values than soccer athletes (1.20±0.21) and volleyball athletes (1.25±0.28).ConclusionsCR for males may be analyzed together, as there were no significant differences between them. However, for females, the CR for softball athletes should be analyzed individually. As there were several differences between the overhead sports according to the FRs, the authors suggest caution in grouping overhead athletes across multiple sports. These results could have important implications for the design of injury prevention and rehabilitation programs associated with the shoulder joint in overhead sports.Level of Evidence3  相似文献   
56.
Fetal persistent middle cerebral artery reversed end diastolic flow is a rare and ominous finding. Previous cases have been associated with intracranial hemorrhage, growth restriction, anaemia, and hepatic anomaly. Intrauterine demise or early neonatal death is a common outcome. We report the case of persistent middle cerebral artery reversed end diastolic flow in a well-grown fetus at 32 weeks’ gestation resulting from acute, severe anaemia due to a large feto-maternal hemorrhage. An emergency cesarean section was performed and the neonate required advanced resuscitation and immediate blood transfusion. Postnatal magnetic resonance imaging confirmed a hemorrhagic parietal infarct and bilateral ischaemic changes in the basal ganglia. This provides further evidence that persistent middle cerebral artery reversed end diastolic flow in any fetus is an ominous finding warranting urgent diagnostic evaluation and/or delivery.  相似文献   
57.
Hantaviruses are zoonotic viruses harbored by rodents, bats, and shrews. At present, only rodent-borne hantaviruses are associated with severe illness in humans. New species of hantaviruses have been recently identified in bats and shrews greatly expanding the potential reservoirs and ranges of these viruses. Brazil has one of the highest incidences of hantavirus cardiopulmonary syndrome in South America, hence it is critical to know what is the prevalence of hantaviruses in Brazil. Although much is known about rodent reservoirs, little is known regarding bats. We captured 270 bats from February 2012 to April 2014. Serum was screened for the presence of antibodies against a recombinant nucleoprotein (rN) of Araraquara virus (ARAQV). The prevalence of antibody to hantavirus was 9/53 with an overall seroprevalence of 17%. Previous studies have shown only insectivorous bats to harbor hantavirus; however, in our study, of the nine seropositive bats, five were frugivorous, one was carnivorous, and three were sanguivorous phyllostomid bats.Hantaviruses (family Bunyaviridae) are present throughout the globe in rodents, bats, and shrews.1 Humans exposed to rodent excreta from hantaviral reservoirs may develop life-threatening diseases. However, none of the other reservoirs are associated with human illness presently.1,2 Bats (order Chiroptera) are known to harbor a broad diversity of emerging zoonotic pathogens.2 Their ability to fly and social behavior favors maintenance, evolution, and spread of pathogens.1,2 The prevailing hypothesis has been that hantaviruses have coevolved with their rodent reservoirs over millions of years.1,3 With the recognition of new species of hantavirus in bats in Africa and Asia,4 Guo and others5 hypothesized that hantaviruses originated primarily in bats and then spilled over into rodents and shrews, but it seems that shrews are the original hosts from which the viruses jumped into both rodents and bats.3 To determine if New World bats in Brazil may harbor hantaviruses, we screened bat sera for antibodies that react against the recombinant nucleoprotein (rN) of Araraquara hantavirus (ARAQV).Bats were collected at five ecologically distinct sites in the northeast region of São Paulo state (sites 1–3) and north region of Minas Gerais state (sites 4 and 5), southeastern Brazil (Figure 1 and 9 and one specimen per species by trap-night was anesthetized to collect blood by cardiac puncture; blood samples were stored in cryovials and flash-frozen in liquid nitrogen. At sites 4 and 5, five specimens per trap-night were randomly selected for blood collection. All bats were handled and sampled according to Sikes and others10 guidelines. This research project, along with its procedures and protocols, is in accordance with Brazilian environment and wildlife protection laws and regulations, and have been approved by the Chico Mendes Institute of Biodiversity Conservation (Ministry of Environment, Brasília, Distrito Federal, Brazil.), protocols nos. 19838-1 and 41709-3. It has also been approved by the Ethics Committee for Animal Research of University of São Paulo and Federal University of Minas Gerais (nos. 020/2011 and 333/2013, respectively). From 270 captured bats, 53 were bled for detection of immunoglobulin G (IgG) antibodies to rN-ARAQV by indirect enzyme-linked immunosorbent assay (ELISA) using anti-bat (Bethyl Laboratories, Inc., Montgomery, TX) secondary antibody. This ELISA, as previously described, showed 97.2% sensitivity, 100% specificity, 100% positive predictive value, and 98.1% negative predictive value when compared with an IgG-ELISA using rN antigen of Andes virus, which is the serological test for hantavirus most used in South America.11,12Open in a separate windowFigure 1.Study areas, highlighting the states of São Paulo and Minas Gerais in southeastern Brazil. The map shows cities where bats have been captured.

Table 1

Trap sites general features6
Trap sites/altitude (m)City/stateMain vegetationSecondary vegetationFeatures
1JES/600Luis Antonio/SPCerrado*Semideciduous forestContinuous Cerrado
2NEF/775Cajuru/SPGrasslandCerradoMonocultures
3SGF/860Batatais/SPSugarcaneCerradoMonocultures
4SEP/872Montes Claros/MGDry forest7CerradoKarst topography
5LGEP/1,009Montes Claros/MGCerrado8Gallery forestCaves and shelters
Open in a separate windowJES = Jatai Ecological Station; LGEP = Lapa Grande Ecological Park; MG = Minas Gerais state; NEF = Nova Esperança Farm; SEP = Sapucai Ecological Park; SGF = Santa Gabriela Farm; SP = Sao Paulo state.*Cerrado = Brazilian savanna-like biome.Dry forest = deciduous seasonal forest.Nine bats had IgG antibodies to ARAQV, which represents an overall seroprevalence of 17%. Five of these bats were from São Paulo state and four were from Minas Gerais state. Of these, five were frugivorous, one was carnivorous, and three were sanguivorous (
FamilySpeciesCapturedInfected/testedMain feeding items
PhyllostomidaeArtibeus lituratus411/6Fruits
PhyllostomidaeA. obscurus21/2Fruits
PhyllostomidaeA. planirostris411/3Fruits
PhyllostomidaeCarollia perspicillata431/10Fruits and insects
PhyllostomidaeChiroderma villosum11/1Fruits
PhyllostomidaeChrotopterus auritus11/1Small vertebrates
PhyllostomidaeDesmodus rotundus113/5Mammals blood
PhyllostomidaeGlossophaga soricina220/5Nectar and pollen
PhyllostomidaeLonchophylla spp.10/1Nectar and pollen
PhyllostomidaeMicronycteris minuta10/1Insects
MolossidaeMolossops neglectus10/1Insects
MolossidaeMolossops temminckii20/1Insects
VespertilionidaeMyotis nigricans130/5Insects
VespertilionidaeMyotis albescens40/1Insects
PhyllostomidaePlatyrrhinus lineatus230/4Fruits
PhyllostomidaeSturnira lilium380/6Fruits
Open in a separate windowrN-ARAQV = recombinant nucleoprotein of Araraquara virus.Main feeding items are shown according to Gardner.9Bats evolution is dated around 50 million years ago, and they are distributed widely in the world, on all continents, except Antarctica.2,13 Perhaps, because of their ancient origin certain viruses seem to be coevolved with them. Thus, maintenance and transmission of these viruses crossed species barriers to infect wild and domestic mammals and also humans.2,13,14 Antibodies to viruses such as Hendra, Ebola, and severe acute respiratory syndrome (SARS)-like coronavirus (CoV) have been detected in wild bats, demonstrating that these animals are able to mount an antibody response, including IgM, IgE, IgA, and multiple IgG classes.14 Although bats may be persistently infected with many viruses, evidence from experimental and naturally infected bats has shown that they rarely produce an antibody response, probably because they are able to control viral replication via the innate immune antiviral response, and therefore, show a low viremia.13,14 However, here we were capable to show bats with IgG antibodies against the rN-ARAQV. The ELISA essays using rN-ARAQV as antigen have been previously used in hantavirus serologic surveys in rodents.15,16 Previous studies with bats of the Old World showed that only insectivorous bats are infected with hantavirus.5 Our study emphasizes that hantaviruses are infecting bats of several species and of different trophic groups in Brazil (15,16 Despite, we have found antibodies against hantavirus, our results only support the idea that these bats become infected in some moment of their lifetime. Further studies in bats are necessary to detect the species and genotype of the infecting hantavirus and then determine the viral load in distinct organ tissues of these animals. Therefore, virus isolation followed by infection experiments could provide additional information if bats actually play a role as reservoirs of hantaviruses. Regardless of the negative public impression of bats, they possess important roles on insect control,17 reseeding forests, and pollinate plants that provide human and animal food.18 Bat guano is used as a fertilizer and for manufacturing soaps, gasohol, and antibiotics. Besides, bat echolocation and the infrared radiation of vampire bats (Desmodus rotundus) have provided models for sonar and infrared systems, respectively.13,19Our study gives insights into ecology, conservational biology, and public health. These data may be useful to understand patterns of hantavirus evolution, in bats and other reservoirs, and to understand the virus dynamics and their potential public health importance. It is also important to preserve the native environment of these animals. Hence, this is the first report of the presence of hantavirus antibodies in phyllostomid bats in southeastern Brazil and also the first report of hantavirus antibodies among bats in the Americas.  相似文献   
58.
Treatment outcomes of integrase inhibitors,boosted protease inhibitors and nonnucleoside reverse transcriptase inhibitors in antiretroviral‐naïve persons starting treatment     
A Mocroft  B Neesgard  R Zangerle  A Rieger  A Castagna  V Spagnuolo  A Antinori  FC Lampe  M Youle  JJ Vehreschild  C Mussini  V Borghi  J Begovac  C Duvivier  HF Gunthard  A Rauch  J Tiraboschi  N Chkhartishvili  N Bolokadze  F Wit  JC Wasmuth  S De Wit  C Necsoi  C Pradier  V Svedhem  C Stephan  K Petoumenos  H Garges  F Rogatto  L Peters  L Ryom   《HIV medicine》2020,21(9):599-606
  相似文献   
59.
CLM94, a novel cyclic amide with anti-VEGFR-2 and antiangiogenic properties, is active against primary anaplastic thyroid cancer in vitro and in vivo     
Antonelli A  Bocci G  La Motta C  Ferrari SM  Fallahi P  Ruffilli I  Di Domenicantonio A  Fioravanti A  Sartini S  Minuto M  Piaggi S  Corti A  Alì G  Di Desidero T  Berti P  Fontanini G  Danesi R  Da Settimo F  Miccoli P 《The Journal of clinical endocrinology and metabolism》2012,97(4):E528-E536
  相似文献   
60.
Can fasting plasma glucose and glycated hemoglobin levels predict oral complications following invasive dental procedures in patients with type 2 diabetes mellitus? A preliminary case-control study     
Ana Carolina Fragoso Motta  Cristiane Aparecida Nogueira Bataglion  Maria Cristina Foss-Freitas  Milton Cesar Foss  Marilena Chinali Komesu 《Clinics (S?o Paulo, Brazil)》2013,68(3):427-430

OBJECTIVE:

To evaluate the effects of the levels of glycemic control on the frequency of clinical complications following invasive dental treatments in type 2 diabetic patients and suggest appropriate levels of fasting blood glucose and glycated hemoglobin considered to be safe to avoid these complications.

METHOD:

Type 2 diabetic patients and non-diabetic patients were selected and divided into three groups. Group I consisted of 13 type 2 diabetic patients with adequate glycemic control (fasting blood glucose levels <140 mg/dl and glycated hemoglobin (HbA1c) levels <7%). Group II consisted of 15 type 2 diabetic patients with inadequate glycemic control (fasting blood glucose levels >140 mg/dl and HbA1c levels >7%). Group III consisted of 18 non-diabetic patients (no symptoms and fasting blood glucose levels <100 mg/dl). The levels of fasting blood glucose, glycated HbA1c, and fingerstick capillary glycemia were evaluated in diabetic patients prior to performing dental procedures. Seven days after the dental procedure, the frequency of clinical complications (surgery site infections and systemic infections) was examined and compared between the three study groups. In addition, correlations between the occurrence of these outcomes and the glycemic control of diabetes mellitus were evaluated.

RESULTS:

The frequency of clinical outcomes was low (4/43; 8.6%), and no significant differences between the outcome frequencies of the various study groups were observed (p>0.05). However, a significant association was observed between clinical complications and dental extractions (p = 0.02).

CONCLUSIONS:

Because of the low frequency of clinical outcomes, it was not possible to determine whether fasting blood glucose or glycated HbA1c levels are important for these clinical outcomes.  相似文献   
[首页] « 上一页 [1] [2] [3] [4] [5] 6 [7] [8] [9] [10] [11] 下一页 » 末  页»
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