全文获取类型
收费全文 | 813篇 |
免费 | 71篇 |
国内免费 | 13篇 |
专业分类
儿科学 | 33篇 |
妇产科学 | 23篇 |
基础医学 | 73篇 |
口腔科学 | 5篇 |
临床医学 | 124篇 |
内科学 | 130篇 |
皮肤病学 | 11篇 |
神经病学 | 82篇 |
特种医学 | 99篇 |
外科学 | 130篇 |
综合类 | 41篇 |
一般理论 | 3篇 |
预防医学 | 46篇 |
眼科学 | 8篇 |
药学 | 45篇 |
肿瘤学 | 44篇 |
出版年
2022年 | 7篇 |
2021年 | 18篇 |
2020年 | 10篇 |
2019年 | 12篇 |
2018年 | 14篇 |
2017年 | 7篇 |
2016年 | 17篇 |
2015年 | 18篇 |
2014年 | 26篇 |
2013年 | 28篇 |
2012年 | 32篇 |
2011年 | 28篇 |
2010年 | 16篇 |
2009年 | 27篇 |
2008年 | 30篇 |
2007年 | 44篇 |
2006年 | 27篇 |
2005年 | 24篇 |
2004年 | 25篇 |
2003年 | 34篇 |
2002年 | 21篇 |
2001年 | 18篇 |
2000年 | 15篇 |
1999年 | 29篇 |
1998年 | 26篇 |
1997年 | 23篇 |
1996年 | 35篇 |
1995年 | 29篇 |
1994年 | 20篇 |
1993年 | 18篇 |
1992年 | 15篇 |
1991年 | 19篇 |
1990年 | 12篇 |
1989年 | 22篇 |
1988年 | 26篇 |
1987年 | 15篇 |
1986年 | 11篇 |
1985年 | 14篇 |
1984年 | 7篇 |
1983年 | 6篇 |
1982年 | 6篇 |
1981年 | 5篇 |
1980年 | 8篇 |
1979年 | 7篇 |
1978年 | 6篇 |
1976年 | 6篇 |
1975年 | 3篇 |
1974年 | 4篇 |
1971年 | 3篇 |
1966年 | 4篇 |
排序方式: 共有897条查询结果,搜索用时 15 毫秒
91.
92.
Buer BC Meagher JL Stuckey JA Marsh EN 《Proceedings of the National Academy of Sciences of the United States of America》2012,109(13):4810-4815
Noncanonical amino acids have proved extremely useful for modifying the properties of proteins. Among them, extensively fluorinated (fluorous) amino acids seem particularly effective in increasing protein stability; however, in the absence of structural data, the basis of this stabilizing effect remains poorly understood. To address this problem, we solved X-ray structures for three small proteins with hydrophobic cores that are packed with either fluorocarbon or hydrocarbon side chains and compared their stabilities. Although larger, the fluorinated residues are accommodated within the protein with minimal structural perturbation, because they closely match the shape of the hydrocarbon side chains that they replace. Thus, stability increases seem to be better explained by increases in buried hydrophobic surface area that accompany fluorination than by specific fluorous interactions between fluorinated side chains. This finding is illustrated by the design of a highly fluorinated protein that, by compensating for the larger volume and surface area of the fluorinated side chains, exhibits similar stability to its nonfluorinated counterpart. These structure-based observations should inform efforts to rationally modulate protein function using noncanonical amino acids. 相似文献
93.
Patrick Vermette Laurence Meagher Edith Gagnon Hans J. Griesser Charles J. Doillon 《Journal of controlled release》2002,80(1-3):179-195
Liposomes were immobilized onto the surface of perfluorinated polymer tape samples and tissue culture polystyrene well-plates using a multilayer immobilization strategy. In the first step, a thin interfacial bonding layer with surface aldehyde groups was deposited from a glow discharge struck in acetaldehyde vapour. Polyethylenimine was then covalently bound onto the aldehyde groups by reductive amination, followed by covalent binding of NHS-PEG-biotin molecules onto the surface amine groups by carbodiimide chemistry. Next, NeutrAvidin™ protein molecules were bound onto the PEG-biotin layer. Finally, liposomes containing PEG-biotinylated lipids were docked onto the remaining binding sites of the surface-immobilized NeutrAvidin™ molecules. AFM was used to image surface-bound liposomes and revealed a density well below close packing. The release characteristics of the surface-bound liposomes were measured by the fluorescence intensity changes of carboxyfluorescein upon release. Liposomes filled with sodium orthovanadate were surface immobilized and used in two in vitro angiogenesis assays. Marked differences compared to various control samples were observed, demonstrating the utility of drug-filled, surface-bound liposomes for evoking localized, controlled biological host responses proximal to an implanted biomedical device. 相似文献
94.
Spinal malignancies are an essential consideration when a patient presents to a chiropractic office with back pain. This single case report exemplifies the importance of patient presentation and physical examination findings. We must also consider the rationale for x-raying patients on an individual case basis. Textbook cases do not always exist and special diagnostic tests do not always provide a definitive diagnosis of underlying pathology. Even though history and examination findings suggest a routine diagnosis, continual re-evaluation and recognition of the need to change the diagnosis on occasion is extremely important. The patient should not only be thoroughly evaluated upon initial presentation, but also each time they present for treatment. The decision to x-ray a patient is considered important. X-ray examination can be used to confirm a diagnosis or to rule out potential pathologies, and not necessarily done as a routine screening procedure.A case report is presented in which the pathologic signs were not evident on plain film x-rays upon initial presentation. 相似文献
95.
96.
97.
98.
99.
Kavanaugh-McHugh A Tobias JD Doyle T Heitmiller ES Meagher C 《Cardiology in review》2000,8(5):288-306
The uses of transesophageal echocardiography have expanded dramatically over the last decade. With advances in technology, this imaging modality has become readily available for evaluation of the complex pediatric population with congenital heart disease. This article discusses the many uses of transesophageal echocardiography in this population, in the outpatient setting, in the peri-operative period, and in the cardiac catheterization laboratory. 相似文献
100.
On the interaction of rabbit antithrombin III with the luminal surface of the normal and deendothelialized rabbit thoracic aorta in vitro 总被引:2,自引:0,他引:2
Pure rabbit antithrombin III was isotope labeled (with 125I or 3H) by two different methods; neither procedure caused a loss of antithrombin activity although both methods affected the affinity of the protein for Sepharose-heparin. From segments from freshly excised rabbit aorta, the uptake of isotope-labeled antithrombin III by the endothelium was rapid and saturable, although relatively small compared to the uptake of thrombin; binding of 3H-antithrombin III to the endothelium resembled that of 125I-antithrombin III. Transendothelial passage of antithrombin III into the subendothelial layers (intima-media) was slow and progressive. Endothelium binding was not affected by pretreating the vessel with either heparin, thrombin, or glycosaminoglycan-specific enzymes. Endothelium-bound antithrombin III was not selectively displaced by either heparin or thrombin. In contrast, endothelium-bound thrombin was rapidly dislodged by antithrombin III as a thrombin- antithrombin III complex. The surface of the deendothelialized aorta (ie, subjected to a balloon catheter) bound antithrombin III avidly. Pretreatment of the deendothelialized vessel with glycosaminoglycan- specific enzymes, particularly heparitinase, decreased intima-media binding by up to 80%. 125I-antithrombin III, when bound to the deendothelialized vessel surface, was actively displaced by either heparin, thrombin, or by unlabeled antithrombin III. The relatively poor binding of antithrombin III compared with that of thrombin by the endothelium in vitro supports an earlier proposal (Lollar P, Owen WG: J Clin Invest 66:1222-1230, 1980) that thrombin bound to high-affinity sites, possibly pericellular proteoglycan, of the endothelium is inactivated by plasma antithrombin III in vivo. Such a situation probably holds for large arteries at least. 相似文献