全文获取类型
收费全文 | 3420篇 |
免费 | 271篇 |
国内免费 | 4篇 |
专业分类
3695篇 |
出版年
2024年 | 10篇 |
2023年 | 27篇 |
2022年 | 49篇 |
2021年 | 110篇 |
2020年 | 57篇 |
2019年 | 81篇 |
2018年 | 97篇 |
2017年 | 76篇 |
2016年 | 108篇 |
2015年 | 190篇 |
2014年 | 222篇 |
2013年 | 225篇 |
2012年 | 294篇 |
2011年 | 240篇 |
2010年 | 146篇 |
2009年 | 151篇 |
2008年 | 170篇 |
2007年 | 146篇 |
2006年 | 129篇 |
2005年 | 120篇 |
2004年 | 122篇 |
2003年 | 109篇 |
2002年 | 113篇 |
2001年 | 41篇 |
2000年 | 27篇 |
1999年 | 34篇 |
1998年 | 23篇 |
1997年 | 16篇 |
1996年 | 23篇 |
1995年 | 21篇 |
1994年 | 15篇 |
1993年 | 21篇 |
1992年 | 18篇 |
1991年 | 18篇 |
1990年 | 21篇 |
1989年 | 14篇 |
1988年 | 27篇 |
1987年 | 15篇 |
1984年 | 12篇 |
1983年 | 16篇 |
1982年 | 13篇 |
1981年 | 14篇 |
1980年 | 16篇 |
1979年 | 11篇 |
1978年 | 17篇 |
1977年 | 9篇 |
1976年 | 14篇 |
1974年 | 10篇 |
1973年 | 9篇 |
1924年 | 8篇 |
排序方式: 共有3695条查询结果,搜索用时 0 毫秒
51.
Proteomic analysis of microvesicles from plasma of healthy donors reveals high individual variability 总被引:1,自引:0,他引:1
Bastos-Amador P Royo F Gonzalez E Conde-Vancells J Palomo-Diez L Borras FE Falcon-Perez JM 《Journal of Proteomics》2012,75(12):3574-3584
Healthy blood plasma is required for several therapeutic procedures. To maximize successful therapeutic outcomes it is critical to control the quality of blood plasma. Clearly initiatives to improve the safety of blood transfusions will have a high economical and social impact. A detailed knowledge of the composition of healthy blood plasma is essential to facilitate such improvements. Apart from free proteins, lipids and metabolites, blood plasma also contains cell-derived microvesicles, including exosomes and microparticles from several different cellular origins. In this study, we have purified microvesicles smaller than 220nm from plasma of healthy donors and performed proteomic, ultra-structural, biochemical and functional analyses. We have detected 161 microvesicle-associated proteins, including many associated with the complement and coagulation signal-transduction cascades. Several proteases and protease inhibitors associated with acute phase responses were present, indicating that these microvesicles may be involved in these processes. There was a remarkably high variability in the protein content of plasma from different donors. In addition, we report that this variability could be relevant for their interaction with cellular systems. This work provides valuable information on plasma microvesicles and a foundation to understand microvesicle biology and clinical implications. 相似文献
52.
It is commonly assumed that variation in abiotic site conditions influences the number of niches, which in turn affects the potential species richness in an area. Based on theoretical considerations, abiotic variation is often used as an estimator of species richness at broad scales, while at finer landscape scales the diversity of habitat types is used. However, habitat estimators assume the landscape to be composed of discrete, homogeneous patches with sharp boundaries, and such a concept is hard to apply in gradient-dominated landscapes. The aim of this study was therefore to investigate the influence of topographic variability (TV) on species richness at the landscape level (gamma (γ) diversity) and on its components (alpha (α) and beta (β) diversity) at microsite and habitat group levels. Using floristic data from 12 "landscapes" of 1 km2 we investigated the influence on diversity components of two simple and one complex measures of TV. While the standard deviation (SD) of altitude explained a high proportion of the variation in γ diversity (linear regression model, R2 =0.63), the complex measure, SD of solar radiation explained it even better (R2 =0.82). There were strong effects of TV on α and β diversity components at the microsite level, but only marginal increases of the diversity components at the habitat level. Further analyses revealed that the missing increase of the habitat level components was caused by differences between habitat groups and that only grassland diversity components increased significantly with TV. We conclude that TV at a landscape scale has strong effects on niche or microsite diversity and is an appropriate estimator of relative species richness in landscapes that are topographically heterogeneous and gradient dominated. 相似文献
53.
The antagonism of glucocorticoid inhibition of wound healing in rats by growth hormone-releasing factor 总被引:1,自引:0,他引:1
S F Kelley A M Felix H P Ehrlich 《Proceedings of the Society for Experimental Biology and Medicine. Society for Experimental Biology and Medicine (New York, N.Y.)》1990,194(4):320-326
Daily therapeutic injections of cortisone to rats will cause weight loss and impaired wound healing. Weight loss is attributed to the catabolic effect of steroid, whereas impaired healing is associated with reductions in fibroplasia and connective tissue deposition. As the major structural protein component of connective tissue is collagen, its absence is responsible for the retarded gain in wound breaking strength. Cortisone also blocks wound closure by inhibiting wound contraction. An anabolic agent such as growth hormone may antagonize the effect of cortisone on the wound healing process. Endogenous GH can be released from the pituitary by exogenous injections of growth hormone-releasing factor (GRF). Two synthetic GRF peptides, a natural 44-amino acid peptide of the human GRF sequence, GRF-44, and an N-terminally substituted analog 29 residues, GRF-29A, were studied. Each was given twice daily with a single daily injection of cortisone for a 7-day period. Concurrent administration of GRF-44 or GRF-29A and cortisone to rats had no effect on restored body weight loss or inhibited wound contraction. While GRF-44 restored collagen deposition and caused restored wound breaking strength, GRF-29A was ineffective in restoring either. GRF-44, a synthetic peptide that stimulates pituitary release of growth hormone, antagonized some of the inhibiting effect of steroid on wound repair by promoting fibroplasia and collagen deposition. 相似文献
54.
Sulieman Ibraheem Shelash Al-Hawary Saade Abdalkareem Jasim Ahmed Hjazi Enwa Felix Oghenemaro Irwanjot Kaur Abhinav Kumar Ahmed Muzahem Al-Ani Enas R. Alwaily Ahmed Huseen Redhee Yasser Fakri Mustafa 《Cell biochemistry and function》2024,42(2):e3978
Ovarian cancer continues to be a difficult medical issue that affects millions of individuals worldwide. Important platforms for cancer immunotherapy include checkpoint inhibitors, chimeric antigen receptor T cells, bispecific antibodies, cancer vaccines, and other cell-based treatments. To avoid numerous infectious illnesses, conventional vaccinations based on synthetic peptides, recombinant subunit vaccines, and live attenuated and inactivated pathogens are frequently utilized. Vaccine manufacturing processes, however, are not entirely safe and carry a significant danger of contaminating living microorganisms. As a result, the creation of substitute vaccinations is required for both viral and noninfectious illnesses, including cancer. Recently, there has been testing of nucleic acid vaccines, or NAVs, as a cancer therapeutic. Tumor antigens (TAs) are genetically encoded by DNA and mRNA vaccines, which the host uses to trigger immune responses against ovarian cancer cells that exhibit the TAs. Despite being straightforward, safe, and easy to produce, NAVs are not currently thought to be an ideal replacement for peptide vaccines. Some obstacles to this strategy include selecting the appropriate therapeutic agents (TAs), inadequate immunogenicity, and the immunosuppressive characteristic of ovarian cancer. We focus on strategies that have been employed to increase NAVs' effectiveness in the fight against ovarian cancer in this review. 相似文献
55.
Matthias Weiling Christian Lechtenfeld Felix Pfeiffer Lars Frankenstein Diddo Diddens Jian-Fen Wang Sascha Nowak Masoud Baghernejad 《Liver Transplantation》2024,14(5):2303568
The implementation of silicon (Si)-containing negative electrodes is widely discussed as an approach to increase the specific capacity of lithium-ion batteries. However, challenges caused by severe volume changes and continuous (re-)formation of the solid-electrolyte interphase (SEI) on Si need to be overcome. The volume changes lead to electrolyte consumption and active lithium loss, decaying the cell performance and cycle life. Herein, the additive 2-sulfobenzoic acid anhydride (2-SBA) is utilized as an SEI-forming electrolyte additive for SiOx-containing anodes. The addition of 2-SBA to a state-of-the-art carbonate-based electrolyte in high-voltage LiNi0.8Mn0.1Co0.1O2, NMC811||artificial graphite +20% SiOx pouch cells leads to improved electrochemical performance, resulting in a doubled cell cycle life. The origin of the enhanced cell performance is mechanistically investigated by developing an advanced experimental technique based on operando attenuated total reflection Fourier-transform infrared (ATR-FTIR) spectroscopy. The operando ATR-FTIR spectroscopy results elucidate the degradation mechanism via anhydride ring-opening reactions after electrochemical reduction on the anode surface. Additionally, ion chromatography conductivity detection mass spectrometry, scanning electron microscopy, energy dispersive X-ray analysis, and quantum chemistry calculations are employed to further elucidate the working mechanisms of the additive and its degradation products. 相似文献
56.
Jin-Woo Lee Cheng Sun Jinho Lee Dong Jun Kim Won Jung Kang Seungbok Lee Donguk Kim Jinseok Park Tan Ngoc-Lan Phan Zhengping Tan Felix Sunjoo Kim Jung-Yong Lee Xichang Bao Taek-Soo Kim Yun-Hi Kim Bumjoon J. Kim 《Liver Transplantation》2024,14(8):2303872
High power conversion efficiency (PCE), long-term stability, and mechanical robustness are prerequisites for the commercial applications of organic solar cells (OSCs). In this study, a new star-shaped trimer acceptor (TYT-S) is developed and high-performance OSCs with a PCE of 19.0%, high photo-stability (t80% lifetime = 2600 h under 1-sun illumination), and mechanical robustness with a crack-onset strain (COS) of 21.6% are achieved. The isotropic molecular structure of TYT-S affords efficient multi-directional charge transport and high electron mobility. Furthermore, its amorphous structure prevents the formation of brittle crystal-to-crystal interfaces, significantly enhancing the mechanical properties of the OSC. As a result, the TYT-S-based OSCs demonstrate a significantly higher PCE (19.0%) and stretchability (COS = 21.6%) than the linear-shaped trimer acceptor (TYT-L)-based OSCs (PCE = 17.5% and COS = 6.4%) and the small-molecule acceptor (MYT)-based OSCs (PCE = 16.5% and COS = 1.3%). In addition, the increased molecular size of TYT-S, relative to that of MYT and dimer (DYT), suppresses the diffusion kinetics of the acceptor molecules, substantially improving the photostability of the OSCs. Finally, to effectively demonstrate the potential of TYT-S, intrinsically stretchable (IS)-OSCs are constructed. The TYT-S-based IS-OSCs exhibit high device stretchability (strain at PCE80% = 31%) and PCE of 14.4%. 相似文献
57.
Felix Molter Armin W. Thomas Scott A. Huettel Hauke R. Heekeren Peter N. C. Mohr 《PLoS computational biology》2022,18(7)
Choices are influenced by gaze allocation during deliberation, so that fixating an alternative longer leads to increased probability of choosing it. Gaze-dependent evidence accumulation provides a parsimonious account of choices, response times and gaze-behaviour in many simple decision scenarios. Here, we test whether this framework can also predict more complex context-dependent patterns of choice in a three-alternative risky choice task, where choices and eye movements were subject to attraction and compromise effects. Choices were best described by a gaze-dependent evidence accumulation model, where subjective values of alternatives are discounted while not fixated. Finally, we performed a systematic search over a large model space, allowing us to evaluate the relative contribution of different forms of gaze-dependence and additional mechanisms previously not considered by gaze-dependent accumulation models. Gaze-dependence remained the most important mechanism, but participants with strong attraction effects employed an additional similarity-dependent inhibition mechanism found in other models of multi-alternative multi-attribute choice. 相似文献
58.
Ohne ZusammenfassungHerrn Univ.-Prof. Dr. AdolfSperlich zum 80. Geburtstag gewidmet. 相似文献
59.
60.
A. Felix 《BMJ (Clinical research ed.)》1941,1(4184):391-395