全文获取类型
收费全文 | 119664篇 |
免费 | 10353篇 |
国内免费 | 1883篇 |
出版年
2023年 | 568篇 |
2022年 | 1433篇 |
2021年 | 3149篇 |
2020年 | 1902篇 |
2019年 | 2342篇 |
2018年 | 2643篇 |
2017年 | 2086篇 |
2016年 | 3433篇 |
2015年 | 5609篇 |
2014年 | 6361篇 |
2013年 | 7305篇 |
2012年 | 9534篇 |
2011年 | 9162篇 |
2010年 | 5831篇 |
2009年 | 5189篇 |
2008年 | 7027篇 |
2007年 | 6886篇 |
2006年 | 6530篇 |
2005年 | 6120篇 |
2004年 | 5846篇 |
2003年 | 5490篇 |
2002年 | 5107篇 |
2001年 | 1532篇 |
2000年 | 1302篇 |
1999年 | 1609篇 |
1998年 | 1607篇 |
1997年 | 1151篇 |
1996年 | 1099篇 |
1995年 | 985篇 |
1994年 | 941篇 |
1993年 | 879篇 |
1992年 | 900篇 |
1991年 | 790篇 |
1990年 | 767篇 |
1989年 | 652篇 |
1988年 | 609篇 |
1987年 | 512篇 |
1986年 | 469篇 |
1985年 | 533篇 |
1984年 | 639篇 |
1983年 | 495篇 |
1982年 | 578篇 |
1981年 | 546篇 |
1980年 | 459篇 |
1979年 | 370篇 |
1978年 | 375篇 |
1977年 | 334篇 |
1976年 | 302篇 |
1975年 | 263篇 |
1974年 | 287篇 |
排序方式: 共有10000条查询结果,搜索用时 312 毫秒
101.
Tim Schwarting Philipp Lechler Johannes Struewer Marius Ambrock Thomas Manfred Frangen Steffen Ruchholtz Ewgeni Ziring Michael Frink 《PloS one》2015,10(2)
IntroductionSuccessful graft ingrowth following reconstruction of the anterior cruciate ligament is governed by complex biological processes at the tendon-bone interface. The aim of this study was to investigate in an in vitro study the effects of bone morphogenetic protein 7 (BMP-7) on tendon-bone integration.ResultsIn both models, positive effects of BMP-7 on ALP enzyme activity were observed (p<0.001). Additionally, similar results were noted for LDH activity and lactate concentration. BMP-7 stimulation led to a significant increase in OCN expression. Whereas the effects of BMP-7 on tendon monoculture peaked during an early phase of the experiment (p<0.001), the cocultures showed a maximal increase during the later stages (p<0.001). The histological analysis showed a stimulating effect of BMP-7 on extracellular matrix formation. Organized ossification zones and calcium carbonate-like structures were only observed in the BMP-stimulated cell cultures.DiscussionThis study showed the positive effects of BMP-7 on the biological process of tendon-bone integration in vitro. Histological signs of improved mineralization were paralleled by increased rates of osteoblast-specific protein levels in primary bovine osteoblasts and fibroblasts.ConclusionOur findings indicated a role for BMP-7 as an adjuvant therapeutic agent in the treatment of ligamentous injuries, and they emphasized the importance of the transdifferentiation process of tendinous fibroblasts at the tendon-bone interface. 相似文献
102.
103.
104.
Michael J. Hynes 《Journal of genetics》1996,75(3):297-311
Many filamentous fungi of all taxa can now be subject to DNA-mediated transformation. Many dominant selectable markers are available and the range available is increasing as new genes are cloned. Transformation is especially valuable in cloning genes defined by mutations with selectable phenotypes and is allowing investigation of many problems in fungi with good genetic systems. Increasingly sophisticated techniques for inactivating genes, targetingin vitro generated mutations to specific loci, and altering gene expression and its regulation are being developed. These approaches are being used to investigate the wealth of basic and applied biological problems available in filamentous fungi. 相似文献
105.
106.
Aspartate, glutamate, or dicarboxylic acids did not inhibit the activity of a highly purified but not homogeneous preparation of pyruvate carboxylase fromThiobacillus novellus. The only effective inhibitors were end-products of the reaction and to a lesser degree hydroxypyruvate. The latter has not been shown previously to regulate the enzyme's activity. Lineweaver-Burk plots revealed that it was uncompetitive with respect to acetyl CoA with a Kii of 3.6 mM, and noncompetitive with respect to bicarbonate, magnesium ATP, and pyruvate with respective Kii values of 7.1, 5.5, and 6.47 mM. The corresponding Kis values were 7.02, 5.4, and 4.25 mM. A mathematical model is presented that supports the findings. 相似文献
107.
Ying Jin Dan Long Juan Li Ruichao Yu Yueming Song Jie Fang Xi Yang Shu Zhou Shishu Huang Zhihe Zhao 《Journal of cellular physiology》2019,234(9):14838-14851
Bone and tooth, fundamental parts of the craniofacial skeleton, are anatomically and developmentally interconnected structures. Notably, pathological processes in these tissues underwent together and progressed in multilevels. Extracellular vesicles (EVs) are cell-released small organelles and transfer proteins and genetic information into cells and tissues. Although EVs have been identified in bone and tooth, particularly EVs have been identified in the bone formation and resorption, the concrete roles of EVs in bone and tooth development and diseases remain elusive. As such, we review the recent progress of EVs in bone and tooth to highlight the novel findings of EVs in cellular communication, tissue homeostasis, and interventions. This will enhance our comprehension on the skeletal biology and shed new light on the modulation of skeletal disorders and the potential of genetic treatment. 相似文献
108.
Cory Bystrom Shijun Sheng Ke Zhang Michael Caulfield Nigel J. Clarke Richard Reitz 《PloS one》2012,7(9)
Measurement of insulin-like growth factor-1 (IGF-I) has utility for the diagnosis and management of growth disorders, but inter-assay comparison of results has been complicated by a multitude of reference standards, antibodies, detection methods, and pre-analytical preparation strategies. We developed a quantitative LC-MS method for intact IGF-I, which has advantages in throughput and complexity when compared to mass spectrometric approaches that rely on stable isotope dilution analysis of tryptic peptides. Since the method makes use of full-scan data, the assay was easily extended to provide quantitative measurement of IGF-II using the same assay protocol. The validated LC-MS assay for IGF-I and IGF-II provides accurate results across the pediatric and adult reference range and is suitable for clinical use. 相似文献
109.
110.