全文获取类型
收费全文 | 10436篇 |
免费 | 586篇 |
国内免费 | 26篇 |
专业分类
耳鼻咽喉 | 175篇 |
儿科学 | 234篇 |
妇产科学 | 172篇 |
基础医学 | 1265篇 |
口腔科学 | 1242篇 |
临床医学 | 647篇 |
内科学 | 2291篇 |
皮肤病学 | 236篇 |
神经病学 | 841篇 |
特种医学 | 199篇 |
外科学 | 1376篇 |
综合类 | 22篇 |
一般理论 | 4篇 |
预防医学 | 1002篇 |
眼科学 | 168篇 |
药学 | 795篇 |
中国医学 | 92篇 |
肿瘤学 | 287篇 |
出版年
2023年 | 84篇 |
2022年 | 172篇 |
2021年 | 358篇 |
2020年 | 240篇 |
2019年 | 313篇 |
2018年 | 382篇 |
2017年 | 242篇 |
2016年 | 309篇 |
2015年 | 351篇 |
2014年 | 432篇 |
2013年 | 575篇 |
2012年 | 789篇 |
2011年 | 874篇 |
2010年 | 497篇 |
2009年 | 411篇 |
2008年 | 649篇 |
2007年 | 683篇 |
2006年 | 581篇 |
2005年 | 496篇 |
2004年 | 409篇 |
2003年 | 343篇 |
2002年 | 320篇 |
2001年 | 175篇 |
2000年 | 193篇 |
1999年 | 147篇 |
1998年 | 47篇 |
1997年 | 42篇 |
1996年 | 28篇 |
1995年 | 37篇 |
1994年 | 27篇 |
1993年 | 28篇 |
1992年 | 76篇 |
1991年 | 80篇 |
1990年 | 77篇 |
1989年 | 52篇 |
1988年 | 47篇 |
1987年 | 46篇 |
1986年 | 43篇 |
1985年 | 40篇 |
1984年 | 28篇 |
1983年 | 26篇 |
1979年 | 21篇 |
1974年 | 18篇 |
1972年 | 13篇 |
1971年 | 16篇 |
1970年 | 23篇 |
1969年 | 33篇 |
1968年 | 31篇 |
1967年 | 15篇 |
1965年 | 14篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
de Lima LC Duarte JB Lépore Neto FP Abe PT Gastaldi AC 《Medical engineering & physics》2005,27(2):181-187
This article aims to characterize the mechanical behaviour of the Flutter VRP1, a respiratory physiotherapy device designed to aid sputum clearance of the airways of patients. The device resembles a smoking pipe with a conical cavity containing a stainless steel sphere which floats up and down while the patient comes with a forced expiration through it. The sphere's oscillatory movement is function of the air flow rate and angular orientation of the device. When the sphere's oscillatory frequency matches the natural frequency of the patient's chestwall+abdomen system, it will produce resonance which, in turn, will enhance sputum clearance. A dynamical model of the Flutter was formulated and an experimental setup was assembled in order to study the oscillatory frequency of the sphere under different conditions of air flow rate, fluid pressure, angular orientation and sphere's material and weight. Interesting results presented by this article point to eventual mechanical optimization of the device and show information that could be beneficial to the professional of the respiratory physiotherapy. 相似文献
62.
63.
R. C. P. Lima-Júnior D. I. M. Sousa G. A. C. Brito G. M. Cunha M. H. Chaves V. S. N. Rao F. A. Santos 《Inflammation research》2007,56(12):487-494
Objective and design: We previously described the visceral antinociceptive property of α, β-amyrin in a mouse model of cystitis induced by cyclophosphamide
(CPM). This study examined the contribution of vanilloid-1 (TRPV1), peripheral NK1 receptors to CPM-evoked nociceptive behaviors
and bladder edema, and its possible modulation by α, β-amyrin.
Methods: The effect of α, β-amyrin (10, 30, and 100 mg/kg, p. o.) and N-acetylcysteine (NAC) on CPM (400 mg/kg, i. p.)-induced cystitis
was studied in mice. Sensory deafferentation was done by a high dose capsaicin. The parameters analysed were: CPM-evoked noxious
behaviors, bladder edema, vascular permeability, and NK1 immunoreactivity. To assess the role of K+
ATP channels in α, β-amyrin effect, animals were pretreated with glibenclamide.
Results: α, β-amyrin (30 and 100 mg/kg) and NAC significantly (p < 0.01) suppressed the visceral pain-related behaviors and NK1 immunoreactivity, but bladder edema was reduced weakly. Glibenclamide reversed the effects of α, β-amyrin. Sensory deafferentation
by capsaicin significantly reduced the nociceptive responses and the NK1 immunoreactivity to noxious stimulation by CPM.
Conclusions: α, β-amyrin attenuates CPM-induced visceral pain and bladder edema by mechanisms that involve, at least in part, a block either
of Substance P release or its receptor function, and partly by opening K+
ATP channels.
Received 13 February 2007; returned for revision 13 April 2007; accepted by G. Geisslinger 14 May 2007 相似文献
64.
da Cunha JP Nakayasu ES Elias MC Pimenta DC Téllez-Iñón MT Rojas F Muñoz MJ Manuel M Almeida IC Schenkman S 《Molecular and biochemical parasitology》2005,140(1):75-86
Histone H1 of most eukaryotes is phosphorylated during the cell cycle progression and seems to play a role in the regulation of chromatin structure, affecting replication and chromosome condensation. In trypanosomatids, histone H1 lacks the globular domain and is shorter when compared with the histone of other eukaryotes. We have previously shown that in Trypanosoma cruzi, the agent of Chagas' disease, histone H1 is phosphorylated and this increases its dissociation from chromatin. Here, we demonstrate using mass spectrometry analysis that T. cruzi histone H1 is only phosphorylated at the serine 12 in the sequence SPKK, a typical cyclin-dependent kinase site. We also found a correlation between the phosphorylation state of histone H1 and the cell cycle. Hydroxyurea and lactacystin, which, respectively, arrest parasites at the G1/S and G2/M stages of the cell cycle, increased the level of histone H1 phosphorylation. Cyclin-dependent kinase-related enzymes TzCRK3, and less intensely the TzCRK1 were able to phosphorylate histone H1 in vitro. Histone H1 dephosphorylation was prevented by treating the parasites with okadaic acid but not with calyculin A. These findings suggest that T. cruzi histone H1 phosphorylation is promoted by cyclin dependent kinases, present during S through G2 phase of the cell cycle, and its dephosphorylation is promoted by specific phosphatases. 相似文献
65.
Filho OG Gordan AN Mello Rde A Neto CS Heinke T 《International journal of surgical pathology》2004,12(2):151-153
Hamartomas were first described by Albrecht in 1904, who defined them as tumor-like malformations in which there was abnormal blending of the normal components of an organ. The myoid hamartoma is a rare benign lesion of the breast and has an uncertain origin, possibly in the walls of the blood vessels, muscularis mammillae of the areolae, and mainly in myoepithelium. We report 3 cases of myoid hamartomas of the breast, with the clinical, radiologic, and histopathological findings, and review the literature. The 3 lesions showed normal breast ducts and lobules, entrapped by a muscular stroma and some foci of mature adipose tissue. The muscular origin of part of the stroma was confirmed by strong reactiveness with smooth-muscle actin. 相似文献
66.
de Cunha DA Eadie LH Barbur JL Hawkes DJ Seifalian AM 《Computers in biology and medicine》2004,34(7):615-632
Some medical applications rely on the use of colour in the diagnostic process, even when poor colour reproduction can affect diagnosis. In this paper, we investigate the effect colour distortion can have on assessment of livers for possible transplantation. We compare the diagnostic effects for the likely colour shifts when illuminant and camera remain uncalibrated or when a monitor is incorrectly calibrated. We describe methods that can result in accurate reproduction of image colour on visual displays and determine whether accurate colour reproduction is necessary for effective liver assessment. 相似文献
67.
Gil LH Alves FP Zieler H Salcedo JM Durlacher RR Cunha RP Tada MS Camargo LM Camargo EP Pereira-da-Silva LH 《Journal of medical entomology》2003,40(5):636-641
Studies on seasonal anopheline fauna variation were performed in two distinct settlements in the State of Rond?nia, Brazil: one at the Madeira River banks (Portuchuelo) with stable native Amazonian population; the other at an inland lumber-extracting farm (Urupá) in dry land, in which adults are mostly migrants. During a 6-yr period (1994-2000), 8,638 adult anophelines were collected: 2,684 in Urupá and 5,954 in Portuchuelo. Anopheles darlingi represented >95% of total mosquitoes caught. Dissection of 4,424 A. darlingi females yielded a very low sporozoite infection index below 0.1%. Oocysts were found in both localities in approximately 0.1% of dissected mosquitoes. Determination of the hour biting rates disclosed seasonal variations in both localities. However, in Portuchuelo, mosquito density peaked at the acme of the rainy season, whereas at Urupá it peaked in the dry season. The increase in mosquito density and incidence of malaria cases were coincident. The high mosquito densities observed in the riverine settlement of Portochuelo sector B, which permits evaluation in > 10,000 mosquitoes' bites/person/year, could explain, in spite of the low mosquito's infection index, the previously described development of natural immunity in the local population that is not observed in the dry land agroindustrial settlement of Urupá. 相似文献
68.
C. Barja-Fidalgo C. R. Carlini J. A. Guimarães C. A. Flores F. Q. Cunha S. H. Ferreira 《Inflammation》1992,16(1):1-12
Canatoxin (Cntx), a toxic protein purified fromCanavalia ensiformis seeds, was shown to have lipoxygenase-mediated effects either in vivo or in vitro. Data here show that Cntx induced a dose-dependent migration of neutrophils and mononuclear cells when injected into rat peritoneal cavities. Furthermore, Cntx was able to induce neutrophil migration into pleural cavities and into air pouches. These effects were inhibited by dexamethasone but not by inhibitors of arachidonic acid metabolism (indomethacin, NDGA, and BW-755c) or by a PAF antagonist (BN 52021). In the peritoneal cavity Cntx caused an increase in vascular permeability inhibited by dexamethasone and BW-755c. Neutrophil migration induced by this toxin was dependent on the number of resident macrophages, since the migratory effect was enhanced by increasing the peritoneal macrophage population with thioglycollate pretreatmen; and was diminished when this population was reduced by peritoneal wash. It was also observed that Cntx induced release of a chemotactic factor from macrophage monolayers in vitro. Dexamethasone blocked this release but did not affect in vivo neutrophil recruitment induced by that factor. These data suggest that Cntx-induced neutrophil migration may be mediated by the same macrophage-derived neutrophil chemotactic factor released by other stimuli such as LPS, IL-1, and INF-gamma. 相似文献
69.
Summary Trehalose-6-phosphate synthase is another example of an enzyme of carbohydrate metabolism, in Saccharomyces, which could be regulated by interconversion of forms. Deactivation was mediated both in vivo and in vitro by a cyclic AMP-dependent protein kinase. Reversibility of this process was obtained by a phosphatase treatment leading to an increase in activity. The phosphorylated, less active form of the enzyme proved to be more susceptible to activation by ATP.Mg. Mutants with well defined lesions in the cyclic AMP-dependent protein kinase system were used to corroborate our findings of a possible regulatory mechanism of trehalose-6-phosphate synthase activity by interconversion of forms.Abbreviations PMSF
phenyl-methyl-sulfonyl fluoride
- G-6-P
glucose-6-phosphate
- UDPG
uridine-5-diphosphoglucose
- PEP
phosphoenol pyruvate
- NAD+
-nicotinamine adenine dinueleotide
- ATP
adenonise 5-triphosphate
- cAMP
adenosine 2:3-cyclic monophosphate
- MOPS
3 (N-morpholino) propanesulfonic acid 相似文献
70.
Pérez C Tous M Gallego S Zala N Rabinovich O Garbiero S Martínez MJ Cunha AM Camino S Cámara A Costa SC Larrondo M Francalancia V Landreau F Bartomioli MA 《Journal of medical virology》2004,72(4):661-667
Human herpesvirus-8 (HHV-8) causes Kaposi's sarcoma (KS) and lymphoproliferative disorders in both HIV-infected and uninfected patients. HHV-8 has a worldwide occurrence but infection rates vary according to a combination of geographic and behavioral risks. The main transmission route seems to be sexual, nevertheless, nasal secretions, saliva, blood, and organ graft have been proposed. HHV-8 was postulated as a new infectious agent for screening in blood donors. The aim of this study was to evaluate the prevalence of antibodies against HHV-8 antigens in blood donors of South America. Serum samples from 2,470 blood donors from Argentina, Brazil, and Chile corresponding to five geographic regions were studied by indirect immunofluorescence assay (IFA). Seroprevalence rate was 3.7% (92/2,470; 95% CI 2.9-4.5) in the entire blood donor population distributed as follows: Argentina, 4.0% (Buenos Aires city, 4.3%; Bahia Blanca, 2.4%; and Córdoba, 4.0%), Campinas (Brazil), 2.8%; and Santiago de Chile, 3.0%. There was no difference (P>0.05) between men and women or age related, except in Brazil where positive cases were 30-49-year-old males. The present study, which includes different geographical areas of multiple countries from South America, has not been done before. The results show similar prevalence rates among the studied zones corresponding to low-prevalence regions. South America is a large sub-continent with a wide spectrum of population and geographical characteristics, thus, more HHV-8 prevalence studies should be necessary to establish possible regional differences. 相似文献