全文获取类型
收费全文 | 5591篇 |
免费 | 683篇 |
国内免费 | 202篇 |
出版年
2021年 | 70篇 |
2020年 | 56篇 |
2019年 | 61篇 |
2018年 | 68篇 |
2017年 | 63篇 |
2016年 | 90篇 |
2015年 | 143篇 |
2014年 | 159篇 |
2013年 | 219篇 |
2012年 | 292篇 |
2011年 | 249篇 |
2010年 | 180篇 |
2009年 | 173篇 |
2008年 | 212篇 |
2007年 | 243篇 |
2006年 | 187篇 |
2005年 | 174篇 |
2004年 | 199篇 |
2003年 | 168篇 |
2002年 | 205篇 |
2001年 | 169篇 |
2000年 | 188篇 |
1999年 | 146篇 |
1998年 | 98篇 |
1997年 | 62篇 |
1996年 | 63篇 |
1995年 | 55篇 |
1993年 | 52篇 |
1992年 | 132篇 |
1991年 | 114篇 |
1990年 | 156篇 |
1989年 | 102篇 |
1988年 | 105篇 |
1987年 | 107篇 |
1986年 | 91篇 |
1985年 | 94篇 |
1984年 | 85篇 |
1983年 | 58篇 |
1982年 | 92篇 |
1981年 | 75篇 |
1980年 | 64篇 |
1979年 | 87篇 |
1978年 | 76篇 |
1977年 | 70篇 |
1976年 | 54篇 |
1975年 | 68篇 |
1974年 | 53篇 |
1973年 | 56篇 |
1972年 | 53篇 |
1971年 | 46篇 |
排序方式: 共有6476条查询结果,搜索用时 15 毫秒
901.
902.
Friedl Weber 《Plant Systematics and Evolution》1956,103(4):475-476
Ohne Zusammenfassung 相似文献
903.
904.
Molecular dynamics simulations of a tetraheme cytochrome c3 were performed to investigate dynamic aspects of the motion of the axial heme iron ligands. It was found that persistent transitions between alternate axial imidazole orientations of the histidine incorporated in the CXXCH heme binding sequence occurred via correlated motions. The correlated motions involved virtually all of the atoms comprising the polypeptide backbone of the heme binding sequence as well as the histidine imidazole side-chain. 相似文献
905.
906.
907.
Michel Adamina Reto Schumacher Paul Zajac Walter P. Weber Rachel Rosenthal Célia Groeper 《Journal of liposome research》2013,23(3):195-204
Malignant tumors represent a major source of disability and account for more than one of five deaths in Western countries. Among the different cancers, melanoma harbors two distinctive features. First, its has long been recognized as an immunogenic tumor, and second, an unprecedented rise in incidence is currently observed, in face of few therapeutic options. Thus, melanoma represent an ideal target for a cancer immunotherapy program. To date, a number of immunodominant epitopes from tumor associated antigens (TAA) are used as cancer vaccines in clinical trials, in spite of an acknowledged rapid degradation in vivo and low immunogenicity. However, most of the immunotherapy trials reported so far do not achieve consistent clinical results. Hence, there is an urgent need for the development of a carrier system and strong adjuvants suitable for a TAA-based cancer immunotherapy. Liposomes and their further development as virosomes with added adjuvancy may address both these issues. We report here our experience in the tailoring of dedicated advanced liposomal vectors that were developed in the context of an upcoming immunotherapy clinical trial for melanoma. 相似文献
908.
Enhanced healing of cutaneous wounds in rats using beads with positively charged surfaces. 总被引:1,自引:0,他引:1
T A Mustoe D A Weber M Krukowski 《Plastic and reconstructive surgery》1992,89(5):891-7; discussion 898-9
The efficacy of electrical fields in soft-tissue repair is unclear. Materials with a charged surface provide a localized charged environment. We examined the effects of surface-charged particles in wound healing in rats with paired dorsal incisions with one side serving as a control. Tensiometry demonstrated that after 10 days, wounds with positively charged particles were 53 percent stronger (p less than 0.001) than controls (10 rats, 30 wound strips), whereas differences with negatively charged (6 rats, 15 strips) or uncharged beads (11 rats, 33 strips) were insignificant. Histologically, wounds with positively charged particles were characterized by large quantities of collagen-rich connective tissue and by prominent bead-associated giant cells. At 94 days, no differences in wound strength were noted. This method of creating charged local environments has potential clinical implications and may add insights into the behavior of cells in response to charged stimuli. 相似文献
909.
E Holler H Fischer C Weber H Stopper H Steger H Simek 《European journal of biochemistry》1987,163(2):397-405
Two forms of a DNA polymerase have been purified from microplasmodia of Physarum polycephalum by poly(ethyleneimine) precipitation and chromatography on DEAE-Sephacel, phosphocellulose, heparin Sepharose, hydroxyapatite, DNA-agarose, blue-Sepharose. They were separated from DNA polymerase alpha on phosphocellulose and from each other on heparin-Sepharose. Form HS1 enzyme was 30-40% pure and form HS2 enzyme 60% with regard to protein contents of the preparations. Form HS2 enzyme was generated from form HS1 enzyme on prolonged standing of enzyme preparations. The DNA polymerases were obtained as complexes of a 60-kDa protein associated with either a 135-kDa (HS1) or a 110-kDa (HS2) DNA-polymerizing polypeptide in a 1:1 molar stoichiometry. The biochemical function of the 60-kDa protein remained unknown. The complexes tended to dissociate during gradient centrifugation and during partition chromatography as well as during polyacrylamide gradient gel electrophoresis under nondenaturing conditions at high dilutions of samples. Both forms existed in plasmodia extracts, their proportions depending on several factors including those which promoted proteolysis. The DNA polymerases resembled eucaryotic DNA polymerase beta by several criteria and were functionally indistinguishable from each other. It is suggested that lower eucaryotes contain repair DNA polymerases, which are similar to those of eubacteria on a molecular mass basis. 相似文献
910.
Renata G. Rosa Paulo P. Joazeiro Juares Bianco Manuela Kunz Joanna F. Weber Stephen D. Waldman 《PloS one》2014,9(8)
The reconstruction of the external ear to correct congenital deformities or repair following trauma remains a significant challenge in reconstructive surgery. Previously, we have developed a novel approach to create scaffold-free, tissue engineering elastic cartilage constructs directly from a small population of donor cells. Although the developed constructs appeared to adopt the structural appearance of native auricular cartilage, the constructs displayed limited expression and poor localization of elastin. In the present study, the effect of growth factor supplementation (insulin, IGF-1, or TGF-β1) was investigated to stimulate elastogenesis as well as to improve overall tissue formation. Using rabbit auricular chondrocytes, bioreactor-cultivated constructs supplemented with either insulin or IGF-1 displayed increased deposition of cartilaginous ECM, improved mechanical properties, and thicknesses comparable to native auricular cartilage after 4 weeks of growth. Similarly, growth factor supplementation resulted in increased expression and improved localization of elastin, primarily restricted within the cartilaginous region of the tissue construct. Additional studies were conducted to determine whether scaffold-free engineered auricular cartilage constructs could be developed in the 3D shape of the external ear. Isolated auricular chondrocytes were grown in rapid-prototyped tissue culture molds with additional insulin or IGF-1 supplementation during bioreactor cultivation. Using this approach, the developed tissue constructs were flexible and had a 3D shape in very good agreement to the culture mold (average error <400 µm). While scaffold-free, engineered auricular cartilage constructs can be created with both the appropriate tissue structure and 3D shape of the external ear, future studies will be aimed assessing potential changes in construct shape and properties after subcutaneous implantation. 相似文献