全文获取类型
收费全文 | 902篇 |
免费 | 49篇 |
专业分类
951篇 |
出版年
2024年 | 1篇 |
2023年 | 12篇 |
2022年 | 15篇 |
2021年 | 19篇 |
2020年 | 23篇 |
2019年 | 24篇 |
2018年 | 26篇 |
2017年 | 27篇 |
2016年 | 39篇 |
2015年 | 80篇 |
2014年 | 56篇 |
2013年 | 71篇 |
2012年 | 84篇 |
2011年 | 82篇 |
2010年 | 42篇 |
2009年 | 40篇 |
2008年 | 40篇 |
2007年 | 34篇 |
2006年 | 29篇 |
2005年 | 20篇 |
2004年 | 25篇 |
2003年 | 20篇 |
2002年 | 17篇 |
2001年 | 15篇 |
2000年 | 19篇 |
1999年 | 20篇 |
1998年 | 5篇 |
1997年 | 8篇 |
1996年 | 3篇 |
1995年 | 8篇 |
1994年 | 6篇 |
1993年 | 2篇 |
1992年 | 6篇 |
1991年 | 3篇 |
1989年 | 4篇 |
1988年 | 3篇 |
1987年 | 4篇 |
1986年 | 1篇 |
1985年 | 2篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1981年 | 1篇 |
1978年 | 3篇 |
1975年 | 1篇 |
1974年 | 2篇 |
1973年 | 4篇 |
1972年 | 1篇 |
1970年 | 1篇 |
1968年 | 1篇 |
排序方式: 共有951条查询结果,搜索用时 15 毫秒
191.
192.
Modeling studies are now a significant part of mainstream research in motor control. Novel and classical modeling techniques used in recent work on small and large motor systems illustrate the different roles that models play in furthering our understanding of motor systems. The models presented reveal single neuron short-term memory, unexpected effects of reciprocal inhibition and methods for decoding activity in large populations of neurons. 相似文献
193.
The black scabbardfish is a deep-sea teleost species with high commercial interest in the NE Atlantic. While it is caught
by large offshore trawlers in the North of Europe, in the south it is captured by artisanal longlines. On the Portuguese continental
slope, in the south of ICES Division IXa, a longline fleet has been engaged in the capture of black scabbardfish for more
than 20 years. This paper reviews and analyses the features of this fishery from a temporal perspective based on information
from different data sources. The fishery is based on the port of Sesimbra, where a family type fishing community strives to
keep catches profitable without altering the artisanal features that characterizes the fleet. Although the fleet has experienced
some technical improvements through time, the fishing operations and strategy have changed very little. Fishing occurs at
particular areas on the slope, where individual vessels have their own fishing grounds. Annual landings surpassed 4,000 tonnes
in the early 1990’s, but decreased to nearly 3,000 tonnes and have remained at this level since 2000. The length structure
of the landings was stable from 2000 to 2005, with a modal (total length) class of 1,090 mm. Monthly landings per unit effort
estimated by a generalized linear model did not present any marked trend for the period 2000–2004. The landings reported in
mainland Portugal were compared with the ones from other regions of the ICES area and the different characteristics of the
fisheries operating in the north and south of Europe were analysed. 相似文献
194.
195.
Analysis of 28 strains of Drosophila buzzatii from six different localities revealed that populations from southern Brazil apparently differ from northeastern populations in chromosome structure. Of the 16 polymorphic chromosome inversions detected in this species, only two (2j and 5c2) were present in southern populations. The Northeastern populations were the first of this species found not to have the 2j inversion. This suggests that the populations of Drosophila buzzatii may have lost chromosome polymorphism during dispersion, supporting the idea that the current geographic distribution of this species in South America is due to active dispersion. 相似文献
196.
Spondias mombin supplementation attenuated cardiac remodelling process induced by tobacco smoke 下载免费PDF全文
Maria Angélica Martins Lourenço Mariana Gobbo Braz Aline Garcia Aun Bruna Letícia Buzati Pereira Amanda Menezes Figueiredo Renata Aparecida Cândido da Silva Elisa Moya Kazmarek Patrícia Helena Correa Alegre Tatiana Fernanda Bachiega Silmeia Garcia Zanati Paula Schmidt Azevedo Bertha Furlan Polegato Ana Angélica Henrique Fernandes Sergio Alberto Rupp de Paiva Leonardo Antonio Mamede Zornoff Marcos Ferreira Minicucci 《Journal of cellular and molecular medicine》2018,22(8):3996-4004
The objective of this study was to investigate the influence of Spondias mombin (SM) supplementation on the cardiac remodelling process induced by exposure to tobacco smoke (ETS) in rats. Male Wistar rats were divided into 4 groups: group C (control, n = 20) comprised animals not exposed to cigarette smoke and received standard chow; group ETS (n = 20) comprised animals exposed to cigarette smoke and received standard chow; group ETS100 (n = 20) received standard chow supplemented with 100 mg/kg body weight/d of SM; and group ETS250 (n = 20) received standard chow supplemented with 250 mg/kg body weight/d of SM. The observation period was 2 months. The ETS animals had higher values of left cardiac chamber diameters and of left ventricular mass index. SM supplementation attenuated these changes. In addition, the myocyte cross‐sectional area (CSA) was lower in group C compared with the ETS groups; however, the ETS250 group had lower values of CSA compared with the ETS group. The ETS group also showed higher cardiac levels of lipid hydroperoxide (LH) compared with group C; and, groups ETS100 and ETS250 had lower concentrations of LH compared with the ETS group. Regarding energy metabolism, SM supplementation decreased glycolysis and increased the β‐oxidation and the oxidative phosphorylation. There were no differences in the expression of Nrf‐2, SIRT‐1, NF‐κB, interferon‐gamma and interleukin 10. In conclusion, our results suggest that ETS induced the cardiac remodelling process. In addition, SM supplementation attenuated this process, along with oxidative stress reduction and energy metabolism modulation. 相似文献
197.
Yu-Ru Su Chongzhi Di Stephanie Bien Licai Huang Xinyuan Dong Goncalo Abecasis Sonja Berndt Stephane Bezieau Hermann Brenner Bette Caan Graham Casey Jenny Chang-Claude Stephen Chanock Sai Chen Charles Connolly Keith Curtis Jane Figueiredo Manish Gala Li Hsu 《American journal of human genetics》2018,102(5):904-919
198.
Prevalence of neuropathic pain and sensory alterations after dental implant placement in a university‐based oral surgery department: A retrospective cohort study 下载免费PDF全文
199.
Genetic variation and divergence of Leuciscus pyrenaicus and L. carolitertii (Pisces, Cyprinidae) 总被引:1,自引:0,他引:1
M. M. Coelho R. M. Brito T. R. Pacheco D. Figueiredo A. M. Pires 《Journal of fish biology》1995,47(SA):243-258
The taxonomy of the genus Leuciscus in the Iberian Peninsula has been presented on the basis of morphological analysis. Two species are believed to occur in Portuguese inland waters, L. carolitertii , the northern basins chub, and L. pyrenaicus , which was described for the Tejo and southern basins. Since only slight differences in the meristic and morphometric characters are observed, the distinction between the two species has been made previously mainly on the basis of osteology. In order to investigate the patterns of genetic differentiation between these species, 24 sites were sampled for both species, and examined electrophoretically for the study of variation at 27 presumptive loci. The results pointed to different levels of population differentiation among drainages and support the recognition of the species level for L. pyrenaicus and L. carolitertii. Our results also suggested that the distribution area of L. pyrenaicus is probably restricted to Tejo and to the small drainages near Tejo, while L. carolitertii seems to have a widespread distribution area, including Lima, Douro, Vouga, Mondego, Guadina and Sado drainages. Moreover, concerning the southern populations, Mira and Arade, the surprisingly high level of differentiation observed at several loci, supports the existence of a further species occurring in these small drainages. The evolutionary aspects related to that differentiation are discussed. 相似文献
200.
Effects of fetal bovine serum, FSH and 17beta-estradiol on the culture of bovine preantral follicles 总被引:1,自引:0,他引:1
Hulshof SC Figueiredo JR Beckers JF Bevers MM van der Donk JA van den Hurk R 《Theriogenology》1995,44(2):217-226
We describe a 7-d culture in droplets of collagen gel of isolated small bovine preantral follicles in medium with or without 10% fetal bovine serum (FBS). In addition, the effect of human recombinant FSH and 17beta-estradiol on the morphology and growth of the preantral follicles was investigated in medium without FBS. After culture in medium with 10% FBS, the increase in follicle diameter was 13.1 +/- 8.4 microm, the percentage of BrdU-labeled cells was 49.9 +/- 11.3 and the number of cells per area granulosa was 11.1 +/- 1.8. Omission of serum from the culture medium had no effect on the percentage of labeled cells, but the diameter increase was lower and the cells were smaller. Apparently, serum affects the size of the granulosa cells from small preantral follicles rather than the stimulation of cell proliferation. Addition of human recombinant FSH and/or 17beta-estradiol to serum-free medium resulted in a larger diameter increase during culture compared with that of the control. With FSH, this was due to an increase in cell proliferation, while with estradiol this was caused by an increase in granulosa cell size. The effects of simultaneous treatment with FSH and estradiol was simply the combination of their individual effects. In conclusion, small bovine preantral follicles can be cultured for 7 d in the absence of serum and hormones. The follicles increase in diameter and react to FSH with enhanced cell proliferation and to estradiol with an increase in cell size. 相似文献