全文获取类型
收费全文 | 630篇 |
免费 | 71篇 |
国内免费 | 1篇 |
学科分类
生物科学 | 702篇 |
出版年
2023年 | 4篇 |
2020年 | 8篇 |
2019年 | 5篇 |
2018年 | 4篇 |
2017年 | 10篇 |
2016年 | 16篇 |
2015年 | 25篇 |
2014年 | 29篇 |
2013年 | 25篇 |
2012年 | 42篇 |
2011年 | 28篇 |
2010年 | 16篇 |
2009年 | 23篇 |
2008年 | 35篇 |
2007年 | 22篇 |
2006年 | 15篇 |
2005年 | 27篇 |
2004年 | 14篇 |
2003年 | 23篇 |
2002年 | 28篇 |
2001年 | 25篇 |
2000年 | 14篇 |
1999年 | 15篇 |
1998年 | 9篇 |
1997年 | 5篇 |
1996年 | 9篇 |
1993年 | 4篇 |
1992年 | 11篇 |
1991年 | 12篇 |
1990年 | 11篇 |
1989年 | 9篇 |
1988年 | 7篇 |
1987年 | 13篇 |
1986年 | 13篇 |
1985年 | 6篇 |
1984年 | 12篇 |
1983年 | 14篇 |
1982年 | 12篇 |
1981年 | 7篇 |
1980年 | 9篇 |
1979年 | 11篇 |
1978年 | 6篇 |
1977年 | 9篇 |
1976年 | 9篇 |
1975年 | 3篇 |
1974年 | 11篇 |
1973年 | 7篇 |
1972年 | 7篇 |
1971年 | 3篇 |
1970年 | 3篇 |
排序方式: 共有702条查询结果,搜索用时 203 毫秒
71.
Innala L Möller B Ljung L Magnusson S Smedby T Södergren A Öhman ML Rantapää-Dahlqvist S Wållberg-Jonsson S 《Arthritis research & therapy》2011,13(4):R131
Introduction
Co-morbidity and mortality due to cardiovascular disease (CVD) are increased in patients with rheumatoid arthritis (RA). Most published studies in this field are retrospective or cross sectional. We investigated the presence of traditional and disease related risk factors for CVD at the onset of RA and during the first five years following diagnosis. We also evaluated their potential for predicting a new cardiovascular event (CVE) during the five-year follow-up period and the modulatory effect of pharmacological treatment. 相似文献72.
73.
Bioprospecting is the exploration of biodiversity for new resources of social and commercial value. It is carried out by a wide range of established industries such as pharmaceuticals, manufacturing and agriculture as well as a wide range of comparatively new ones such as aquaculture, bioremediation, biomining, biomimetic engineering and nanotechnology. The benefits of bioprospecting have emerged from such a wide range of organisms and environments worldwide that it is not possible to predict what species or habitats will be critical to society, or industry, in the future. The benefits include an unexpected variety of products that include chemicals, genes, metabolic pathways, structures, materials and behaviours. These may provide physical blueprints or inspiration for new designs. Criticism aimed at bioprospecting has been addressed, in part, by international treaties and legal agreements aimed at stopping biopiracy and many activities are now funded by agencies that require capacity-building and economic benefits in host countries. Thus, much contemporary bioprospecting has multiple goals, including the conservation of biodiversity, the sustainable management of natural resources and economic development. Ecologists are involved in three vital ways: first, applying ecological principles to the discovery of new resources. In this context, natural history becomes a vast economic database. Second, carrying out field studies, most of them demographic, to help regulate the harvest of wild species. Third, emphasizing the profound importance of millions of mostly microscopic species to the global economy. 相似文献
74.
Average paternal age is increasing in many high income countries, but the implications of this demographic shift for child health and welfare are poorly understood. There is equivocal evidence that children of older fathers are at increased risk of neurodevelopmental disorders and reduced IQ. We therefore report here on the relationship between paternal age and a composite indicator of scholastic achievement during adolescence, i.e. compulsory school leaving grades, among recent birth cohorts in Stockholm County where delayed paternity is notably common. We performed a record-linkage study comprising all individuals in Stockholm County who finished 9 years of compulsory school from 2000 through 2007 (n = 155,875). Data on school leaving grades and parental characteristics were retrieved from administrative and health service registers and analyzed using multiple linear regression. Advancing paternal age at birth was not associated with a decrease in school leaving grades in adolescent offspring. After adjustment for year of graduation, maternal age and parental education, country of birth and parental mental health service use, offspring of fathers aged 50 years or older had on average 0.3 (95% CI −3.8, 4.4) points higher grades than those of fathers aged 30–34 years. In conclusion, advancing paternal age is not associated with poorer school performance in adolescence. Adverse effects of delayed paternity on offspring cognitive function, if any, may be counterbalanced by other potential advantages for children born to older fathers. 相似文献
75.
VEGF receptor-2 Y951 signaling and a role for the adapter molecule TSAd in tumor angiogenesis 总被引:9,自引:0,他引:9
Matsumoto T Bohman S Dixelius J Berge T Dimberg A Magnusson P Wang L Wikner C Qi JH Wernstedt C Wu J Bruheim S Mugishima H Mukhopadhyay D Spurkland A Claesson-Welsh L 《The EMBO journal》2005,24(13):2342-2353
Vascular endothelial growth factor receptor-2 (VEGFR-2) activation by VEGF-A is essential in vasculogenesis and angiogenesis. We have generated a pan-phosphorylation site map of VEGFR-2 and identified one major tyrosine phosphorylation site in the kinase insert (Y951), in addition to two major sites in the C-terminal tail (Y1175 and Y1214). In developing vessels, phosphorylation of Y1175 and Y1214 was detected in all VEGFR-2-expressing endothelial cells, whereas phosphorylation of Y951 was identified in a subset of vessels. Phosphorylated Y951 bound the T-cell-specific adapter (TSAd), which was expressed in tumor vessels. Mutation of Y951 to F and introduction of phosphorylated Y951 peptide or TSAd siRNA into endothelial cells blocked VEGF-A-induced actin stress fibers and migration, but not mitogenesis. Tumor vascularization and growth was reduced in TSAd-deficient mice, indicating a critical role of Y951-TSAd signaling in pathological angiogenesis. 相似文献
76.
77.
Zierhut B Daneva T Gartner W Brunnmaier B Mineva I Berggård T Wagner L 《Biochemical and biophysical research communications》2005,329(4):1193-1199
We describe two new variants of the recently identified hexa-EF-hand calcium binding protein secretagogin. The first variant (secretagogin-R22) is characterized by one single amino acid exchange (Q/R) at codon 22, most likely due to RNA editing. The second variant of secretagogin (setagin) consists of 49 amino acids. Due to a frame shift, only the first 27 amino acids are identical to secretagogin. We demonstrate that this protein truncation results in complete loss of the calcium binding capacity. Setagin expression was found in considerable amounts in the pancreas whereas secretagogin and secretagogin-R22 were also found in the central nervous system and organs containing neurendocrine cells. 相似文献
78.
Johansson BP Levander F von Pawel-Rammingen U Berggård T Björck L James P 《Journal of proteome research》2005,4(6):2302-2311
During the course of infection, the common human pathogen Streptococcus pyogenes encounters plasma. We show that plasma causes S. pyogenes to rapidly remodel its cellular metabolism and virulence pathways. We also identified a variant of the major virulence factor, M1 protein, lacking 13 amino acids at the NH(2)-terminus in bacteria grown with plasma. The pronounced effect of plasma on protein expression, suggests this is an important adaptive mechanism with implications for S. pyogenes pathogenicity. 相似文献
79.
Magnusson U Salopek-Sondi B Luck LA Mowbray SL 《The Journal of biological chemistry》2004,279(10):8747-8752
The periplasmic leucine-binding protein is the primary receptor for the leucine transport system in Escherichia coli. We report here the structure of an open ligand-free form solved by molecular replacement and refined at 1.5-A resolution. In addition, two closed ligand-bound structures of the same protein are presented, a phenylalanine-bound form at 1.8 A and a leucine-bound structure at a nominal resolution of 2.4 A. These structures show the basis of this protein's ligand specificity, as well as illustrating the conformational changes that are associated with ligand binding. Comparison with earlier structures provides further information about solution conformations, as well as the different specificity of the closely related leucine/isoleucine/valine-binding protein. 相似文献
80.
J Bojsen-M?ller K K Kalliokoski M Sepp?nen M Kjaer S P Magnusson 《Journal of applied physiology》2006,101(1):196-201
The metabolic activity of tendinous tissues has traditionally been considered to be of limited magnitude. However, recent studies have suggested that glucose uptake increases in the force-transmitting tissues as a response to contractile loading, which in turn indicates an elevated tissue metabolism. The purpose of the present study was to investigate whether such a mechanism could be observed for the human Achilles tendon following tensile loading. Six subjects participated in the study. Unilateral Achilles tendon loading was applied by 25-min intermittent voluntary plantar flexor contractions. A radioactive tracer ([18F]-2-fluoro-2-deoxy-D-glucose) was administered during muscle action, and glucose uptake was measured by use of PET. Regions of interest were defined on the PET images corresponding to the cross section of Achilles tendon at two longitudinally separated sites (insertion and free tendon). Glucose uptake index was determined within respective regions of interest for the active and resting leg. Tendon force during voluntary contractions was approximately 13% of maximal voluntary contraction force. Tendon loading induced an elevated glucose uptake index compared with that of the contralateral resting tendon in the region of tendon insertion (0.13 +/- 0.05 vs. 0.09 +/- 0.02; P < 0.05) and at the free tendon (0.12 +/- 0.01 vs. 0.08 +/- 0.02; P < 0.05). The present data suggest that tissue metabolism is elevated in the human Achilles tendon in response to low-intensity loading. 相似文献