全文获取类型
收费全文 | 1358篇 |
免费 | 137篇 |
出版年
2023年 | 8篇 |
2022年 | 13篇 |
2021年 | 22篇 |
2020年 | 19篇 |
2019年 | 15篇 |
2018年 | 20篇 |
2017年 | 22篇 |
2016年 | 35篇 |
2015年 | 67篇 |
2014年 | 63篇 |
2013年 | 96篇 |
2012年 | 88篇 |
2011年 | 104篇 |
2010年 | 74篇 |
2009年 | 53篇 |
2008年 | 68篇 |
2007年 | 55篇 |
2006年 | 67篇 |
2005年 | 62篇 |
2004年 | 54篇 |
2003年 | 58篇 |
2002年 | 50篇 |
2001年 | 26篇 |
2000年 | 21篇 |
1999年 | 17篇 |
1998年 | 12篇 |
1997年 | 11篇 |
1996年 | 10篇 |
1995年 | 9篇 |
1994年 | 13篇 |
1993年 | 6篇 |
1992年 | 15篇 |
1991年 | 19篇 |
1990年 | 20篇 |
1989年 | 13篇 |
1988年 | 13篇 |
1987年 | 13篇 |
1986年 | 13篇 |
1985年 | 16篇 |
1984年 | 15篇 |
1983年 | 17篇 |
1982年 | 13篇 |
1981年 | 6篇 |
1980年 | 7篇 |
1979年 | 8篇 |
1977年 | 9篇 |
1976年 | 5篇 |
1974年 | 11篇 |
1973年 | 10篇 |
1969年 | 6篇 |
排序方式: 共有1495条查询结果,搜索用时 15 毫秒
51.
Capsule A newly created wetland has been beneficial for the breeding of five heron species and for the settlement and expansion of Glossy Ibises in the region. Aim To determine whether created wetland would lead to the establishment of a heron and ibis breeding colony, and if so, to determine its effects on the distribution of these species in the wider region. Methods Number of pairs breeding at the new wetland and in the region were estimated annually from 1996 to 2008. We investigated whether the growth of the new colony was explained by redistribution of breeding pairs within the region. Results Purple Herons, Squacco Herons and Glossy Ibises colonised the new wetland in 1996. Black‐crowned Night Herons settled in 1998, while Cattle and Little Egrets were the last species to establish in the mixed colony in 2001. The population increase was particularly marked for Glossy Ibises (which had bred in Doñana only sporadically through the 20th century). Our findings suggest that simple redistribution of pairs does not explain the formation and growth of the new colony. Since the first year of establishment numbers of Glossy Ibises and Purple Herons have shown a significant growth trend at both the new colony and in Doñana. Conclusion The creation and management of a new wetland has been successful for the conservation of heron and egret species and promoted the expansion of the Glossy Ibis population across the western Mediterranean region. 相似文献
52.
Activity of native hydrolytic enzymes and their association with the cell wall of three ectomycorrhizal fungi 总被引:1,自引:0,他引:1
Alfredo Pérez-de-Mora Bianca Reuter Marianna Lucio Alfred Ahne Michael Schloter Karin Pritsch 《Mycorrhiza》2013,23(3):185-197
The ecological and biogeochemical relevance of hydrolytic enzymes associated with the fungal cell wall has been poorly studied in ectomycorrhizal (ECM) fungi. We used a modified sequential extraction procedure to investigate the activity of various hydrolytic enzymes (β-glucosidase, acid-phosphatase, leucine-aminopeptidase, chitinase, xylanase and glucuronidase) and their association with the cell wall of three ECM fungi (Rhizopogon roseolus, Paxillus involutus and Piloderma croceum). Fungi were grown on C-rich solid medium under three different P concentrations (3.7, 0.37 and 0.037 mM). The sequential extraction procedure classifies enzymes as: (a) cytosolic, (b) loosely bound, (c) hydrophobically bound, (d) ionically bound and (e) covalently bound. Results showed that for the same fungus absolute enzymatic activity was affected by P concentration, whilst enzymatic compartmentalization among the cytosol and the cell wall fractions was not. The association of enzymes with the cell wall was fungus- and enzyme-specific. Our data indicate also that enzymes best known for being either extracellular or cytosolic or both, do act in muro as well. The ecological implications of cell wall-bound enzymes and the potential applications and limitations of sequential extractions are further discussed. 相似文献
53.
Rachel P. Wildman Dan Wang Ivonne Fernandez Peter Mancuso Nanette Santoro Philipp E. Scherer MaryFran R. Sowers 《Obesity (Silver Spring, Md.)》2013,21(3):629-636
Objective:
Regulators of adipose tissue hormones remain incompletely understood, but may include sex hormones. As adipose tissue hormones have been shown to contribute to numerous metabolic and cardiovascular disorders, understanding their regulation in midlife women is of clinical importance. Therefore, we assessed the associations between testosterone (T) and sex hormone binding globulin (SHBG) with leptin, high molecular weight (HMW) adiponectin, and the soluble form of the leptin receptor (sOB‐R) in healthy midlife women.Design and Methods:
Cross‐sectional analyses were performed using data from 1,881 midlife women (average age 52.6 (±2.7) years) attending the sixth Annual follow‐up visit of the multiethnic Study of Women's Health Across the Nation.Results:
T was weakly negatively associated with both HMW adiponectin and sOB‐R (r = ?0.12 and r = ?0.10, respectively; P < 0.001 for both), and positively associated with leptin (r = 0.17; P < 0.001). SHBG was more strongly and positively associated with both HMW adiponectin and sOB‐R (r = 0.29 and r = 0.24, respectively; P < 0.001 for both), and more strongly and negatively associated with leptin (r = ?0.27; P < 0.001). Adjustment for fat mass, insulin resistance, or waist circumference only partially diminished associations with HMW adiponectin and sOB‐R, but attenuated associations with leptin. In conclusion, in these midlife women, lower SHBG values, and to a lesser extent, higher T levels, were associated with lower, or less favorable, levels of adiponectin and sOB‐R, independent of fat mass.Conclusions:
These data suggest that variation in these adipose hormones resulting from lower SHBG levels, and possibly, though less likely, greater androgenicity, may contribute to susceptibility for metabolic and cardiovascular outcomes during midlife in women.54.
Mayra Cuéllar-Cruz Gerardo Gutiérrez-Sánchez Everardo López-Romero Estela Ruiz-Baca Julio C. Villagómez-Castro Lucio Rodríguez-Sifuentes 《Central European Journal of Biology》2013,8(4):337-345
In the past two decades, Candida species have become the second leading cause of invasive mycosis in immunocompromised patients. In order to colonize their hosts, these microorganisms express adhesins and cell wall proteins that allow them to adhere and neutralize the reactive oxygen species produced by phagocytic cells during the respiratory burst. However, the precise mechanism by which Candida cell wall proteins change their expression in response to oxidative stress has not been described. In an attempt to understand this change in response to oxidative stress, in this study, three Candida species, namely, C. albicans, C. glabrata and C. krusei, were exposed to increasing concentrations of H2O2 and induced cell wall proteins were identified by two-dimensional gel electrophoresis and peptide mass fingerprinting. Sequence analysis of differential proteins led to the identification of two heat-shock proteins in C. albicans, two enolases in C. glabrata and one enolase in C. krusei. Enolases may be involved in the protection of pathogenic cells against oxidative stress as suggested by the decrease in their expression when they were exposed to high concentrations of H2O2. To our knowledge, this is the first demonstration that expression of these proteins changes in response to oxidative stress in different Candida species. This knowledge can eventually facilitate both an early diagnosis and a more efficient treatment of this mycosis. 相似文献
55.
Alexandra D. Ogorodnikova Unab I. Khan Aileen P. McGinn Irfan Zeb Matthew J. Budoff S.M. Harman Virginia M. Miller Eliot A. Brinton JoAnn E. Manson Howard N. Hodis George R. Merriam Marcelle I. Cedars Hugh S. Taylor Frederick Naftolin Rogerio A. Lobo Nanette Santoro Rachel P. Wildman 《Obesity (Silver Spring, Md.)》2013,21(8):1726-1733
56.
On‐chip assessment of human primary cardiac fibroblasts proliferative responses to uniaxial cyclic mechanical strain 下载免费PDF全文
57.
58.
59.
Melo RC Ribeiro C Murray CS Veloso CJ da Silveira CH Neshich G Meira W Carceroni RL Santoro MM 《Genetics and molecular research : GMR》2007,6(4):946-963
We propose a novel method for defining patterns of contacts present in protein-protein complexes. A new use of the traditional contact maps (more frequently used for representation of the intra-chain contacts) is presented for analysis of inter-chain contacts. Using an algorithm based on image processing techniques, we can compare protein-protein interaction maps and also obtain a dissimilarity score between them. The same algorithm used to compare the maps can align the contacts of all the complexes and be helpful in the determination of a pattern of conserved interactions at the interfaces. We present an example for the application of this method by analyzing the pattern of interaction of bovine pancreatic trypsin inhibitors and trypsins, chymotrypsins, a thrombin, a matriptase, and a kallikrein - all classified as serine proteases. We found 20 contacts conserved in trypsins and chymotrypsins and 3 specific ones are present in all the serine protease complexes studied. The method was able to identify important contacts for the protein family studied and the results are in agreement with the literature. 相似文献
60.
Leng Yu Wang Hao de Lucio Mario Gomez Hector 《Biomechanics and modeling in mechanobiology》2022,21(6):1825-1840
Biomechanics and Modeling in Mechanobiology - Subcutaneous injection of therapeutic monoclonal antibodies (mAbs) has gained increasing interest in the pharmaceutical industry. The transport,... 相似文献