全文获取类型
收费全文 | 7679篇 |
免费 | 516篇 |
国内免费 | 3篇 |
专业分类
8198篇 |
出版年
2023年 | 48篇 |
2022年 | 94篇 |
2021年 | 181篇 |
2020年 | 108篇 |
2019年 | 128篇 |
2018年 | 173篇 |
2017年 | 190篇 |
2016年 | 268篇 |
2015年 | 420篇 |
2014年 | 435篇 |
2013年 | 522篇 |
2012年 | 624篇 |
2011年 | 531篇 |
2010年 | 353篇 |
2009年 | 317篇 |
2008年 | 400篇 |
2007年 | 442篇 |
2006年 | 383篇 |
2005年 | 358篇 |
2004年 | 340篇 |
2003年 | 317篇 |
2002年 | 297篇 |
2001年 | 86篇 |
2000年 | 52篇 |
1999年 | 88篇 |
1998年 | 84篇 |
1997年 | 62篇 |
1996年 | 51篇 |
1995年 | 59篇 |
1994年 | 54篇 |
1993年 | 55篇 |
1992年 | 48篇 |
1991年 | 49篇 |
1990年 | 53篇 |
1989年 | 33篇 |
1988年 | 36篇 |
1987年 | 16篇 |
1986年 | 30篇 |
1985年 | 28篇 |
1984年 | 29篇 |
1983年 | 19篇 |
1982年 | 28篇 |
1981年 | 24篇 |
1980年 | 14篇 |
1979年 | 17篇 |
1977年 | 12篇 |
1976年 | 19篇 |
1975年 | 13篇 |
1974年 | 21篇 |
1970年 | 16篇 |
排序方式: 共有8198条查询结果,搜索用时 0 毫秒
941.
Juan P. Aguilar Ticona Nivison Nery Jr. Joseph B. Ladines-Lim Claudia Gambrah Gielson Sacramento Bruno de Paula Freitas Joseane Bouzon Jamary Oliveira-Filho Ana Borja Haritha Adhikarla Magelda Montoya Athena Chin Elsio A. Wunder Jr. Verena Ballalai Carina Vieira Rubens Belfort Antonio R. P. Almeida Mitermayer G. Reis Eva Harris Albert I. Ko Federico Costa 《PLoS neglected tropical diseases》2021,15(2)
BackgroundThe prevalence of developmental alterations associated with in-utero Zika virus (ZIKV) exposure in children is not well understood. Furthermore, estimation of the Population Attributable Fraction (PAF) of developmental alterations attributed to ZIKV has not been performed due to lack of population-based cohorts with data on symptomatic and asymptomatic ZIKV exposures and an appropriate control group. The aim of this study was to characterize neurodevelopmental outcomes of children at 11 to 32 months of age with intrauterine ZIKV exposure and estimate the PAF of alterations secondary to ZIKV exposure.Methodology/Principal findingsWe performed a cohort of biannual community-based prospective serosurveys in a slum community in Salvador, Brazil. We recruited women participating in our cohort, with a documented pregnancy from January 2015 to December 2016 and children born to those mothers. Children were classified as ZIKV exposed in utero (born from women with ZIKV seroconversion during pregnancy) or unexposed (born from women without ZIKV seroconversion or that seroconverted before/after pregnancy) by using an IgG monoclonal antibody blockade-of-binding (BoB). We interviewed mothers and performed anthropometric, audiometric, ophthalmological, neurologic, and neurodevelopmental evaluations of their children at 11 to 32 months of age. Among the 655 women participating in the cohort, 66 (10%) were pregnant during the study period. 46 (70%) of them completed follow-up, of whom ZIKV seroconversion occurred before, during, and after pregnancy in 25 (54%), 13 (28%), and 1 (2%), respectively. The rest of women, 7 (21.2%), did not present ZIKV seroconversion. At 11 to 32 months of life, the 13 ZIKV-exposed children had increased risk of mild cognitive delay (RR 5.1; 95%CI 1.1–24.4) compared with the 33 children unexposed, with a PAF of 53.5%. Exposed children also had increased risk of altered auditory behavior (RR 6.0; 95%CI 1.3–26.9), with a PAF of 59.5%.ConclusionsA significant proportion of children exposed in utero to ZIKV developed mild cognitive delay and auditory behavioral abnormalities even in the absence of gross birth defects such as microcephaly and other neurodevelopmental domains. Furthermore, our findings suggest that over half of these abnormalities could be attributed to intrauterine ZIKV exposure. 相似文献
942.
943.
Ricardo Moreira Borges Fernanda das Neves Costa Fernanda O. Chagas Andrew Magno Teixeira Jaewon Yoon Márcio Barczyszyn Weiss Camila Manoel Crnkovic Alan Cesar Pilon Bruno C. Garrido Luz Adriana Betancur Abel M. Forero Leonardo Castellanos Freddy A. Ramos Mônica T. Pupo Stefan Kuhn 《Phytochemical analysis : PCA》2023,34(1):48-55
944.
Renu Tuteja Narendra Tuteja Franco Lilliu Bruno Bembi Renzo Galanello Antonio Cao Francisco E. Baralle 《Human genetics》1994,94(3):314-315
We report a novel mutation in exon 9 of the glucocerebrosidase gene of a patient with Gaucher disease and of Sardinian origin. 相似文献
945.
EF Toussaint FL Condamine GJ Kergoat C Capdevielle-Dulac J Barbut JF Silvain BP Le Ru 《PloS one》2012,7(7):e41377
Between the late Oligocene and the early Miocene, climatic changes have shattered the faunal and floral communities and drove the apparition of new ecological niches. Grassland biomes began to supplant forestlands, thus favouring a large-scale ecosystem turnover. The independent adaptive radiations of several mammal lineages through the evolution of key innovations are classic examples of these changes. However, little is known concerning the evolutionary history of other herbivorous groups in relation with this modified environment. It is especially the case in phytophagous insect communities, which have been rarely studied in this context despite their ecological importance. Here, we investigate the phylogenetic and evolutionary patterns of grass-specialist moths from the species-rich tribe Apameini (Lepidoptera, Noctuidae). The molecular dating analyses carried out over the corresponding phylogenetic framework reveal an origin around 29 million years ago for the Apameini. Ancestral state reconstructions indicate (i) a potential Palaearctic origin of the tribe Apameini associated with a major dispersal event in Afrotropics for the subtribe Sesamiina; (ii) a recent colonization from Palaearctic of the New World and Oriental regions by several independent lineages; and (iii) an ancestral association of the tribe Apameini over grasses (Poaceae). Diversification analyses indicate that diversification rates have not remained constant during the evolution of the group, as underlined by a significant shift in diversification rates during the early Miocene. Interestingly, this age estimate is congruent with the development of grasslands at this time. Rather than clade ages, variations in diversification rates among genera better explain the current differences in species diversity. Our results underpin a potential adaptive radiation of these phytophagous moths with the family Poaceae in relation with the major environmental shifts that have occurred in the Miocene. 相似文献
946.
Aerial parts of Centaurea solstitialis subs schouwii afforded the guaianolides cynaropicrin and aguerin B and the lignans arctigenin and matairesinol. The structure of a third guaianolide previously found also in Centaurea behen was revised. 相似文献
947.
Couchoux H Bichraoui H Chouabe C Altafaj X Bonvallet R Allard B Ronjat M Berthier C 《The international journal of biochemistry & cell biology》2011,43(5):713-720
Caveolin-3 is the striated muscle specific isoform of the scaffolding protein family of caveolins and has been shown to interact with a variety of proteins, including ion channels. Mutations in the human CAV3 gene have been associated with several muscle disorders called caveolinopathies and among these, the P104L mutation (Cav-3(P104L)) leads to limb girdle muscular dystrophy of type 1C characterized by the loss of sarcolemmal caveolin. There is still no clear-cut explanation as to specifically how caveolin-3 mutations lead to skeletal muscle wasting. Previous results argued in favor of a role for caveolin-3 in dihydropyridine receptor (DHPR) functional regulation and/or T-tubular membrane localization. It appeared worth closely examining such a functional link and investigating if it could result from the direct physical interaction of the two proteins. Transient expression of Cav-3(P104L) or caveolin-3 specific siRNAs in C2C12 myotubes both led to a significant decrease of the L-type Ca(2+) channel maximal conductance. Immunolabeling analysis of adult skeletal muscle fibers revealed the colocalization of a pool of caveolin-3 with the DHPR within the T-tubular membrane. Caveolin-3 was also shown to be present in DHPR-containing triadic membrane preparations from which both proteins co-immunoprecipitated. Using GST-fusion proteins, the I-II loop of Ca(v)1.1 was identified as the domain interacting with caveolin-3, with an apparent affinity of 60nM. The present study thus revealed a direct molecular interaction between caveolin-3 and the DHPR which is likely to underlie their functional link and whose loss might therefore be involved in pathophysiological mechanisms associated to muscle caveolinopathies. 相似文献
948.
949.
Fernandez S Jannin V Rodier JD Ritter N Mahler B Carrière F 《Biochimica et biophysica acta》2007,1771(5):633-640
Labrasol is a lipid-based self-emulsifying excipient used in the preparation of lipophilic drugs intended for oral delivery. It is mainly composed of PEG esters and glycerides with medium acyl chains, which are potential substrates for digestive lipases. The hydrolysis of Labrasol by porcine pancreatic extracts, human pancreatic juice and several purified digestive lipases was investigated in the present study. Classical human pancreatic lipase (HPL) and porcine pancreatic lipase, which are the main lipases involved in the digestion of dietary triglycerides, showed very low levels of activity on the entire Labrasol excipient as well as on separated fractions of glycerides and PEG esters. On the other hand, gastric lipase, pancreatic lipase-related protein 2 (PLRP2) and carboxyl ester hydrolase (CEH) showed high specific activities on Labrasol. These lipases were found to hydrolyze the main components of Labrasol (PEG esters and monoglycerides) used as individual substrates, whereas these esters were found to be poor substrates for HPL. The lipolytic activity of pancreatic extracts and human pancreatic juice on Labrasol(R) is therefore mainly due to the combined action of CEH and PLRP2. These two pancreatic enzymes, together with gastric lipase, are probably the main enzymes involved in the in vivo lipolysis of Labrasol taken orally. 相似文献
950.
Faoro V Fink B Taudorf S Dehnert C Berger MM Swenson ER Bailey DM Bärtsch P Mairbäurl H 《American journal of physiology. Regulatory, integrative and comparative physiology》2011,300(1):R32-R39
Hypoxia impairs metabolic functions by decreasing activity and expression of ATP-consuming processes. To separate hypoxia from systemic effects, we tested whether hypoxia at high altitude affects basal and PMA-stimulated leukocyte metabolism and how this compares to acute (15 min) and 24 h of in vitro hypoxia. Leukocytes were prepared at low altitude and ~24 h after arrival at 4559 m. Mitochondrial oxygen consumption (JO?) was measured by respirometry, oxygen radicals by electron spin resonance spectroscopy, both at a Po? = 100 mmHg (JO?,???) and 20 mmHg (JO?,??). Acute hypoxia of leukocytes decreased JO? at low altitude. Exposure to high altitude decreased JO?,???, whereas JO?,?? was not affected. Acute hypoxia of low-altitude samples decreased the activity of complexes I, II, and III. At high altitude, activity of complexes I and III were decreased when measured in normoxia. Stimulation of leukocytes with PMA increased JO?,??? at low (twofold) and high altitude (five-fold). At both locations, PMA-stimulated JO? was decreased by acute hypoxia. Basal and PMA-stimulated reactive oxygen species (ROS) production were unchanged at high altitude. Separate in vitro experiments performed at low altitude show that ~75% of PMA-induced increase in JO? was due to increased extra-mitochondrial JO? (JO?(,res); in the presence of rotenone and antimycin A). JO?(,res) was doubled by PMA. Acute hypoxia decreased basal JO?(,res) by ~70% and PMA-stimulated JO?(,res) by about 50% in cells cultured in normoxia and hypoxia (1.5% O?; 24 h). Conversely, 24 h in vitro hypoxia decreased mitochondrial JO?,??? and JO?,??, extra-mitochondrial, basal, and PMA-stimulated JO? were not affected. These results show that 24 h of high altitude but not 24 h in vitro hypoxia decreased basal leukocyte metabolism, whereas PMA-induced JO? and ROS formation were not affected, indicating that prolonged high-altitude hypoxia impairs mitochondrial metabolism but does not impair respiratory burst. In contrast, acute hypoxia impairs respiratory burst at either altitude. 相似文献