全文获取类型
收费全文 | 5669篇 |
免费 | 549篇 |
出版年
2021年 | 66篇 |
2018年 | 67篇 |
2017年 | 56篇 |
2016年 | 100篇 |
2015年 | 177篇 |
2014年 | 183篇 |
2013年 | 229篇 |
2012年 | 298篇 |
2011年 | 274篇 |
2010年 | 166篇 |
2009年 | 164篇 |
2008年 | 212篇 |
2007年 | 243篇 |
2006年 | 236篇 |
2005年 | 238篇 |
2004年 | 251篇 |
2003年 | 229篇 |
2002年 | 232篇 |
2001年 | 100篇 |
2000年 | 79篇 |
1999年 | 92篇 |
1998年 | 72篇 |
1997年 | 59篇 |
1996年 | 65篇 |
1995年 | 66篇 |
1994年 | 85篇 |
1993年 | 66篇 |
1992年 | 90篇 |
1991年 | 64篇 |
1990年 | 74篇 |
1989年 | 72篇 |
1988年 | 58篇 |
1987年 | 73篇 |
1986年 | 59篇 |
1985年 | 53篇 |
1984年 | 63篇 |
1983年 | 61篇 |
1982年 | 71篇 |
1981年 | 59篇 |
1980年 | 58篇 |
1979年 | 46篇 |
1978年 | 69篇 |
1977年 | 54篇 |
1976年 | 56篇 |
1975年 | 52篇 |
1974年 | 60篇 |
1973年 | 71篇 |
1972年 | 41篇 |
1971年 | 42篇 |
1968年 | 36篇 |
排序方式: 共有6218条查询结果,搜索用时 562 毫秒
51.
52.
H-2RIIBP (RXR beta) heterodimerization provides a mechanism for combinatorial diversity in the regulation of retinoic acid and thyroid hormone responsive genes. 总被引:70,自引:10,他引:60
下载免费PDF全文
![点击此处可从《The EMBO journal》网站下载免费的PDF全文](/ch/ext_images/free.gif)
M S Marks P L Hallenbeck T Nagata J H Segars E Appella V M Nikodem K Ozato 《The EMBO journal》1992,11(4):1419-1435
53.
H-2RIIBP expressed from a baculovirus vector binds to multiple hormone response elements. 总被引:12,自引:0,他引:12
M S Marks B Z Levi J H Segars P H Driggers S Hirschfeld T Nagata E Appella K Ozato 《Molecular endocrinology (Baltimore, Md.)》1992,6(2):219-230
H-2RIIBP is a member of the nuclear hormone receptor superfamily that binds to the region II enhancer of major histocompatibility complex class I genes. Based on its homology with Drosophila XR2C/CF1, H-2RIIBP may play a role in development. By using a baculovirus expression system, a large amount of recombinant H-2RIIBP was produced. The recombinant protein accumulated in the nucleus of insect cells. A series of monoclonal antibodies reacting with the recombinant H-2RIIBP was then generated. A DNA-protein immunoprecipitation assay was developed with these antibodies, enabling the DNA-binding specificity of H-2RIIBP to be distinguished from that of an endogenous region II binding factor expressed in uninfected insect cells. We show that H-2RIIBP binds to estrogen response elements with an affinity comparable to that for the region II enhancer. H-2RIIBP also bound to some, but not all, thyroid hormone response elements and retinoic acid response elements, albeit at a lower affinity. Binding to these elements was demonstrated without exogenous addition of a ligand. The H-2RIIBP binding specificity determined by this assay was in agreement with the specificity assessed by Southwestern and gel mobility shift assays. Furthermore, methylation interference assays indicated that H-2RIIBP recognizes the conserved hormone response motif GG(T/A)CA. Taken together, these data demonstrate that H-2RIIBP is capable of binding to hormone response elements of a variety of genes. They suggest that H-2RIIBP may exert a pleiotropic function. 相似文献
54.
Scott Pownall Christine A. Kozak Keith Schappert Mohan Sarkar Eric Hull Harry Schachter Jamey D. Marth 《Genomics》1992,12(4)
The biosynthesis of protein-bound complex N-glycans in mammals requires a series of covalent modifications governed by a large number of specific glycosyltransferases and glycosidases. The addition of oligosaccharide to an asparagine residue on a nascent polypeptide chain begins in the endoplasmic reticulum. Oligosaccharide processing continues in the Golgi apparatus to produce a diversity of glycan structures. UDP-N-acetylglucosamine:α-3-
-mannoside β-1,2-N-acetylglucosaminyltransferase I (EC 2.4.1.101; GlcNAc-TI) is a key enzyme in the process because it is essential for the conversion of high-mannose N-glycans to complex and hybrid N-glycans. We have isolated the mouse gene encoding GlcNAc-TI (Mgat-1) from a genomic DNA library. The mouse sequence is highly conserved with respect to the human and rabbit homologs and exists as a single protein-encoding exon. Mgat-1 was mapped to mouse Chromosome 11, closely linked to the gene encoding interleukin-3 by the analysis of multilocus interspecies backcrosses. RNA analyses of Mgat-1 expression levels revealed significant variation among normal tissues and cells. 相似文献
55.
56.
M W Marks L C Argenta P H Izenberg L G Mes 《Plastic and reconstructive surgery》1991,87(4):674-8; discussion 679-81
The chest-wall deformity associated with Poland's syndrome was reconstructed in eight male patients 16 to 38 years old (average age 20 years). Follow-up ranged from 1 to 10 years. Two patients had custom silicone implants placed subcutaneously. In one of these patients, the edge of the implant could be seen. Three patients had transfer of an ipsilateral pedicled latissimus dorsi muscle flap with intact thoracodorsal nerve. All these patients had noticeable atrophy of the flap, and one underwent subsequent implantation of a custom silicone implant beneath the flap. Three other patients had a custom silicone implant covered immediately by a latissimus dorsi muscle flap. All four patients who had a combination of silicone implant and latissimus dorsi muscle flap had satisfactory correction of their deformity. 相似文献
57.
Quantitative immunocytochemical staining for recombinant tissue-type plasminogen activator in transfected Chinese hamster ovary cells 总被引:3,自引:0,他引:3
D E Gennaro S T Hoffstein G Marks L Ramos M S Oka M E Reff T K Hart P J Bugelski 《Proceedings of the Society for Experimental Biology and Medicine. Society for Experimental Biology and Medicine (New York, N.Y.)》1991,198(1):591-598
Tissue-type plasminogen activator (tPA) is a serine protease which cleaves plasminogen to its active form, plasmin. tPA plays a physiologic role in hemostasis, wound healing, and embryogenesis. Therapeutically, recombinant human tPA is used as a thrombolytic in myocardial infarction. Although production of therapeutic quantities of tPA in Chinese hamster ovary (CHO) cells transfected with the human gene for tPA is practical, production costs remain high. One important factor which determines the ultimate cost of tPA (or any other recombinant protein expressed in mammalian cells) is its production level on a per cell basis. We have used postembedding immunocytochemical staining with colloidal gold to study the subcellular localization of tPA in CHO cells expressing recombinant tPA (rCHO) in an effort to understand the factor(s) which might limit secretion. Staining for tPA was evaluated visually and by morphometric analysis and was specific and reproducible. Serially passaged rCHO showed no significant change in staining density over 31 serial passages. Staining density was greatest over dilated cisternae of the rough endoplasmic reticulum and nuclear envelope. Golgi stacks and large acid phosphatase-positive vacuoles (probably lysosomes) were also heavily stained. Staining of lysosomal vacuoles suggested that rCHO might be degrading nascent tPA. Incubation of rCHO with 125I-tPA showed that the cells were not internalizing tPA from the media. These results suggest that rCHO fail to secrete a portion of the tPA they synthesize and that it is degraded in lysosomes. This observation may have important implications on the choice of expression systems for efficient production of large quantities of recombinant proteins. 相似文献
58.
59.
Bone cell biology: the regulation of development, structure, and function in the skeleton 总被引:10,自引:0,他引:10
Bone cells compose a population of cells of heterogeneous origin but restricted function with respect to matrix formation, mineralization, and resorption. The local, mesenchymal origin of the cells which form the skeleton contrasts with their extraskeletal, hemopoietic relatives under which bone resorption takes place. However, the functions of these two diverse populations are remarkably related and interdependent. Bone cell regulation, presently in its infancy, is a complicated cascade involving a plethora of local and systemic factors, including some components of the skeletal matrices and other organ systems. Thus, any understanding of bone cell regulation is a key ingredient in understanding not only the development, maintenance, and repair of the skeleton but also the prevention and treatment of skeletal disorders. 相似文献
60.
The toothless (tl) rat is a nonlethal osteopetrotic mutation characterized by the presence of few osteoclasts and the failure to be cured by bone-marrow transplantation. We examined the skeletal biology of tl rats and normal littermates up to 6 weeks after birth. Osteoclasts in tl rats were small, reduced 25-fold in number, and had greatly reduced concentrations of acid hydrolases. Bone shape internally and externally reflected reduced bone resorption, and tl rats were hypophosphatemic and mildly hypocalcemic at 2 weeks. These data indicate that the basic defect in tl rats is one of differentiation of osteoclasts and, coupled with the observation that normal bone-marrow cells cannot develop into osteoclasts in the tl skeleton, suggest that the defect lies in the skeletal micro-environment. 相似文献