全文获取类型
收费全文 | 6353篇 |
免费 | 387篇 |
国内免费 | 1篇 |
专业分类
6741篇 |
出版年
2023年 | 70篇 |
2022年 | 107篇 |
2021年 | 208篇 |
2020年 | 134篇 |
2019年 | 179篇 |
2018年 | 207篇 |
2017年 | 157篇 |
2016年 | 234篇 |
2015年 | 400篇 |
2014年 | 383篇 |
2013年 | 454篇 |
2012年 | 511篇 |
2011年 | 488篇 |
2010年 | 289篇 |
2009年 | 279篇 |
2008年 | 327篇 |
2007年 | 313篇 |
2006年 | 306篇 |
2005年 | 228篇 |
2004年 | 197篇 |
2003年 | 191篇 |
2002年 | 158篇 |
2001年 | 105篇 |
2000年 | 94篇 |
1999年 | 68篇 |
1998年 | 52篇 |
1997年 | 35篇 |
1996年 | 34篇 |
1995年 | 30篇 |
1994年 | 22篇 |
1993年 | 23篇 |
1992年 | 34篇 |
1991年 | 37篇 |
1990年 | 25篇 |
1989年 | 27篇 |
1988年 | 18篇 |
1987年 | 20篇 |
1986年 | 27篇 |
1985年 | 25篇 |
1984年 | 21篇 |
1983年 | 20篇 |
1982年 | 16篇 |
1981年 | 19篇 |
1980年 | 10篇 |
1979年 | 20篇 |
1978年 | 13篇 |
1977年 | 10篇 |
1975年 | 12篇 |
1974年 | 11篇 |
1973年 | 9篇 |
排序方式: 共有6741条查询结果,搜索用时 0 毫秒
161.
Emmanuel S. Buys Yu-Chieh Ko Clemens Alt Sarah R. Hayton Alexander Jones Laurel T. Tainsh Ruiyi Ren Andrea Giani Maeva Clerté Emma Abernathy Robert E. T. Tainsh Dong-Jin Oh Rajeev Malhotra Pankaj Arora Nadine de Waard Binglan Yu Raphael Turcotte Daniel Nathan Marielle Scherrer-Crosbie Stephanie J. Loomis Jae H. Kang Charles P. Lin Haiyan Gong Douglas J. Rhee Peter Brouckaert Janey L. Wiggs Meredith S. Gregory Louis R. Pasquale Kenneth D. Bloch Bruce R. Ksander 《PloS one》2013,8(3)
Primary open angle glaucoma (POAG) is a leading cause of blindness worldwide. The molecular signaling involved in the pathogenesis of POAG remains unknown. Here, we report that mice lacking the α1 subunit of the nitric oxide receptor soluble guanylate cyclase represent a novel and translatable animal model of POAG, characterized by thinning of the retinal nerve fiber layer and loss of optic nerve axons in the context of an open iridocorneal angle. The optic neuropathy associated with soluble guanylate cyclase α1–deficiency was accompanied by modestly increased intraocular pressure and retinal vascular dysfunction. Moreover, data from a candidate gene association study suggests that a variant in the locus containing the genes encoding for the α1 and β1 subunits of soluble guanylate cyclase is associated with POAG in patients presenting with initial paracentral vision loss, a disease subtype thought to be associated with vascular dysregulation. These findings provide new insights into the pathogenesis and genetics of POAG and suggest new therapeutic strategies for POAG. 相似文献
162.
José Leopoldo Ferreira Antunes Tatiana Natasha Toporcov Maria Gabriela Haye Biazevic Antonio Fernando Boing Crispian Scully Stefano Petti 《PloS one》2013,8(7)
Alcohol drinking and tobacco smoking are assumed to have significant independent and joint effects on oral cancer (OC) development. This assumption is based on consistent reports from observational studies, which, however, overestimated the independent effects of smoking and drinking, because they did not account for the interaction effect in multivariable analyses. This case-control study sought to investigate the independent and the joint effects of smoking and drinking on OC in a homogeneous sample of adults. Case patients (N = 1,144) were affected by invasive oral/oropharyngeal squamous cell carcinoma confirmed histologically, diagnosed between 1998 and 2008 in four hospitals of São Paulo (Brazil). Control patients (N = 1,661) were not affected by drinking-, smoking-associated diseases, cancers, upper aero-digestive tract diseases. Cumulative tobacco and alcohol consumptions were assessed anamnestically. Patients were categorized into never/ever users and never/level-1/level-2 users, according to the median consumption level in controls. The effects of smoking and drinking on OC adjusted for age, gender, schooling level were assessed using logistic regression analysis; Model-1 did not account for the smoking-drinking interaction; Model-2 accounted for this interaction and included the resultant interaction terms. The models were compared using the likelihood ratio test. According to Model-1, the adjusted odds ratios (ORs) for smoking, drinking, smoking-drinking were 3.50 (95% confidence interval –95CI, 2.76–4.44), 3.60 (95CI, 2.86–4.53), 12.60 (95CI, 7.89–20.13), respectively. According to Model-2 these figures were 1.41 (95CI, 1.02–1.96), 0.78 (95CI, 0.48–1.27), 8.16 (95CI, 2.09–31.78). Analogous results were obtained using three levels of exposure to smoking and drinking. Model-2 showed statistically significant better goodness-of-fit statistics than Model-1. Drinking was not independently associated with OC, while the independent effect of smoking was lower than expected, suggesting that observational studies should be revised adequately accounting for the smoking-drinking interaction. OC control policies should focus on addictive behaviours rather than on single lifestyle risk factors. 相似文献
163.
Human Hemorrhagic Pulmonary Leptospirosis: Pathological Findings and Pathophysiological Correlations
Thales De Brito Vera Demarchi Aiello Luis Fernando Ferraz da Silva Ana Maria Gon?alves da Silva Wellington Luiz Ferreira da Silva Jussara Bianchi Castelli Antonio Carlos Seguro 《PloS one》2013,8(8)
Background
Leptospirosis is a re-emerging zoonosis with protean clinical manifestations. Recently, the importance of pulmonary hemorrhage as a lethal complication of this disease has been recognized. In the present study, five human necropsies of leptospirosis (Weil‘s syndrome) with extensive pulmonary manifestations were analysed, and the antibodies expressed in blood vessels and cells involved in ion and water transport were used, seeking to better understand the pathophysiology of the lung injury associated with this disease.Principal Findings
Prominent vascular damage was present in the lung microcirculation, with decreased CD34 and preserved aquaporin 1 expression. At the periphery and even inside the extensive areas of edema and intraalveolar hemorrhage, enlarged, apparently hypertrophic type I pneumocytes (PI) were detected and interpreted as a non-specific attempt of clearence of the intraalveolar fluid, in which ionic transport, particularly of sodium, plays a predominant role, as suggested by the apparently increased ENaC and aquaporin 5 expression. Connexin 43 was present in most pneumocytes, and in the cytoplasm of the more preserved endothelial cells. The number of type II pneumocytes (PII) was slightly decreased when compared to normal lungs and those of patients with septicemia from other causes, a fact that may contribute to the progressively low PI count, resulting in deficient restoration after damage to the alveolar epithelial integrity and, consequently, a poor outcome of the pulmonary edema and hemorrhage.Conclusions
Pathogenesis of lung injury in human leptospirosis was discussed, and the possibility of primary non-inflammatory vascular damage was considered, so far of undefinite etiopathogenesis, as the initial pathological manifestation of the disease. 相似文献164.
Elizabeth B. Oliveira-Sales Edgar Maquigussa Patricia Semedo Luciana G. Pereira Vanessa M. Ferreira Niels O. Camara Cassia T. Bergamaschi Ruy R. Campos Mirian A. Boim 《PloS one》2013,8(11)
Renovascular hypertension induced by 2 Kidney-1 Clip (2K-1C) is a renin-angiotensin-system (RAS)-dependent model, leading to renal vascular rarefaction and renal failure. RAS inhibitors are not able to reduce arterial pressure (AP) and/or preserve the renal function, and thus, alternative therapies are needed. Three weeks after left renal artery occlusion, fluorescently tagged mesenchymal stem cells (MSC) (2×105 cells/animal) were injected weekly into the tail vein in 2K-1C hypertensive rats. Flow cytometry showed labeled MSC in the cortex and medulla of the clipped kidney. MSC prevented a further increase in the AP, significantly reduced proteinuria and decreased sympathetic hyperactivity in 2K-1C rats. Renal function parameters were unchanged, except for an increase in urinary volume observed in 2K-1C rats, which was not corrected by MSC. The treatment improved the morphology and decreased the fibrotic areas in the clipped kidney and also significantly reduced renal vascular rarefaction typical of 2K-1C model. Expression levels of IL-1β, TNF-α angiotensinogen, ACE, and Ang II receptor AT1 were elevated, whereas AT2 levels were decreased in the medulla of the clipped kidney. MSC normalized these expression levels. In conclusion, MSC therapy in the 2K-1C model (i) prevented the progressive increase of AP, (ii) improved renal morphology and microvascular rarefaction, (iii) reduced fibrosis, proteinuria and inflammatory cytokines, (iv) suppressed the intrarenal RAS, iv) decreased sympathetic hyperactivity in anesthetized animals and v) MSC were detected at the CNS suggesting that the cells crossed the blood-brain barrier. This therapy may be a promising strategy to treat renovascular hypertension and its renal consequences in the near future. 相似文献
165.
da Silva-Carvalho Lidiane Maria Genovez-Oliveira Jhon Lennon de Souza Oliveira Mariana de Oliveira Águida Aparecida de Lima Viviane Moreira Ferreira Ildemar Berto Bruno Pereira 《Systematic parasitology》2020,97(6):847-855
Systematic Parasitology - Isospora parnaitatiaiensis Silva, Rodrigues, Lopes, Berto, Luz, Ferreira & Lopes, 2015 was identified from a new host, the plain antvireo Dysithamnus mentalis... 相似文献
166.
167.
Luiz F. C. Tencatt Janice Muriel-Cunha Jansen Zuanon Marlon F. C. Ferreira Marcelo R. Britto 《Journal of fish biology》2020,97(4):1072-1086
Aspidoras azaghal n. sp. was discovered during a multitaxonomic scientific expedition to the remote Amazon Terra do Meio region in tributaries to the rio Xingu basin, Pará, Brazil. The new species can be promptly distinguished from its congeners by the following combination of features: (a) absence of the first dorsal-fin element; (b) parieto-supraoccipital fontanel located medially on bone; (c) absence of a longitudinal dark-brown or black stripe along flank midline; (d) ventral surface of trunk covered by clearly smaller, irregular and/or roundish platelets; (e) inner laminar expansion of infraorbital 1 well developed; (f) relatively wide frontal bone, with width equal to half of entire length; (g) absence of a thick, longitudinal conspicuous dark-brown stripe along dorsal portion of flank; and (h) poorly developed serrations on posterior margin of the pectoral-fin spine. Besides morphological evidence, the molecular analyses indicated significant differences between the new species and its congeners, with A. albater and A. raimundi as its closest species, showing 6.53% of genetic differentiation in both cases. The intraspecific molecular data revealed gene flow (peer fixation index, FST = 0.05249, P > 0.05, for the cytochrome oxidase I (COI) marker and FST = -0.01466, P > 0.05, for the control region) between specimens upstream and downstream from a 30-m height waterfall at the type-locality, which therefore represent a single population. Furthermore, it was possible to observe a unidirectional gene flow pattern, with genetic diversity increasing in the downstream direction. 相似文献
168.
Hudson T. Pinheiro Bruno C. L. Macena Ronaldo B. Francini-Filho Carlos E. L. Ferreira Fernanda V. Albuquerque Natalia P. A. Bezerra Alfredo Carvalho-Filho Romulo C. P. Ferreira Osmar J. Luiz Thayna J. Mello Sibele A. Mendonça Diogo M. Nunes Caio R. Pimentel Alessandra M. A. Pires Abilio Soares-Gomes Danielle L. Viana Fabio H. V. Hazin Luiz A. Rocha 《Journal of fish biology》2020,97(4):1143-1153
Saint Peter and Saint Paul's Archipelago (SPSPA), one of the smallest and most isolated island groups in the world, is situated on the Mid-Atlantic Ridge, between Brazil and the African continent. SPSPA has low species richness and high endemism; nonetheless, the diversity of fishes from deep habitats (>30 m depth) had not been previously studied in detail. Several expeditions conducted between 2009 and 2018 explored the shallow and deep reefs of SPSPA using scuba, closed-circuit rebreathers, manned submersibles, baited remote underwater stereo-videos (stereo-BRUV) and fishing between 0 and 1050 m depth. These expeditions yielded 41 new records of fishes for SPSPA: 9 in open waters, 9 in shallow waters (0–30 m), 8 in mesophotic ecosystems (30–150 m) and 15 in deeper reefs (>150 m). Combined with literature records of adult pelagic, shallow and deep-reef species, as well as larvae, the database of the fish biodiversity for SPSPA currently comprises 225 species (169 recorded as adult fishes and 79 as larvae, with 23 species found in both stages). Most of them (112) are pelagic, 86 are reef-associated species and 27 are deep-water specialists. Species accumulation curves show that the number of fish species has not yet reached an asymptote. Whereas the number of species recorded in SPSPA is similar to that in other oceanic islands in the Atlantic Ocean, the proportion of shorefishes is relatively lower, and the endemism level is the third highest in the Atlantic. Twenty-nine species are listed as threatened with extinction. Observations confirm the paucity of top predators on shallow rocky reefs of the island, despite the presence of several pelagic shark species around SPSPA. Because all of the endemic species are reef associated, it is argued that the new marine-protected areas created by the Brazilian government do not ensure the protection and recovery of SPSPA's biodiversity because they allow exploitation of the most vulnerable species around the archipelago itself. This study suggests a ban on reef fish exploitation inside an area delimited by the 1000 m isobath around the islands (where all known endemics are concentrated) as the main conservation strategy to be included in the SPSPA management plan being prepared by the Brazilian government. 相似文献
169.
170.
Bezagio Renata Coltro Colli Cristiane Maria Romera Liara Izabela Lopes de Almeida Caroline Rodrigues Ferreira Érika Cristina Mattia Salete Gomes Mônica Lúcia 《Molecular biology reports》2020,47(2):1233-1239
Molecular Biology Reports - Molecular detection of Giardia duodenalis by polymerase chain reaction (PCR) is difficult in faecal samples due to inhibitors that contaminate DNA preparations, or due... 相似文献