全文获取类型
收费全文 | 100467篇 |
免费 | 6772篇 |
国内免费 | 6983篇 |
出版年
2024年 | 133篇 |
2023年 | 1580篇 |
2022年 | 1652篇 |
2021年 | 3312篇 |
2020年 | 3137篇 |
2019年 | 4278篇 |
2018年 | 3621篇 |
2017年 | 2807篇 |
2016年 | 2840篇 |
2015年 | 3524篇 |
2014年 | 6012篇 |
2013年 | 7680篇 |
2012年 | 4903篇 |
2011年 | 6027篇 |
2010年 | 4745篇 |
2009年 | 5280篇 |
2008年 | 5526篇 |
2007年 | 5691篇 |
2006年 | 5285篇 |
2005年 | 4699篇 |
2004年 | 4220篇 |
2003年 | 3583篇 |
2002年 | 3244篇 |
2001年 | 2327篇 |
2000年 | 1863篇 |
1999年 | 1831篇 |
1998年 | 1709篇 |
1997年 | 1406篇 |
1996年 | 1325篇 |
1995年 | 1225篇 |
1994年 | 1153篇 |
1993年 | 839篇 |
1992年 | 792篇 |
1991年 | 659篇 |
1990年 | 547篇 |
1989年 | 418篇 |
1988年 | 399篇 |
1987年 | 359篇 |
1986年 | 289篇 |
1985年 | 377篇 |
1984年 | 554篇 |
1983年 | 381篇 |
1982年 | 405篇 |
1981年 | 295篇 |
1980年 | 235篇 |
1979年 | 215篇 |
1978年 | 187篇 |
1977年 | 152篇 |
1976年 | 130篇 |
1975年 | 108篇 |
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
121.
The results of a detailed analysis of 100 supernumerary limbs generated by 180° ipsilateral rotation (on the same limb stump) of regeneration blastemas is presented. The limbs were analyzed in terms of their position of origin, frequency, cartilage structure by Victoria blue staining, and muscle structure by serial sections. Single, double, or triple supernumeraries can be produced at no unique position of origin, although the posterodorsal quadrant was preferred. Four classes of supernumerary limbs were generated by such operations—normal; double dorsal or double ventral; part normal/part mirror imaged; part normal/part inverted in approximately equal frequencies. After amputation of these supernumeraries the same muscle patterns are faithfully regenerated. A hypothesis to explain the production of these abnormal limbs is proposed based on the observed phenomenon of fusion of supernumerary blastemata, but their regenerative behaviour presents problems for current models of pattern formation. Similar results have been obtained with developing limb buds and the relation between development and regeneration is discussed. 相似文献
122.
Sixin Jiang Brigitte Heller Vincent S. Tagliabracci Lanmin Zhai Jose M. Irimia Anna A. DePaoli-Roach Clark D. Wells Alexander V. Skurat Peter J. Roach 《The Journal of biological chemistry》2010,285(45):34960-34971
Stbd1 is a protein of previously unknown function that is most prevalent in liver and muscle, the major sites for storage of the energy reserve glycogen. The protein is predicted to contain a hydrophobic N terminus and a C-terminal CBM20 glycan binding domain. Here, we show that Stbd1 binds to glycogen in vitro and that endogenous Stbd1 locates to perinuclear compartments in cultured mouse FL83B or Rat1 cells. When overexpressed in COSM9 cells, Stbd1 concentrated at enlarged perinuclear structures, co-localized with glycogen, the late endosomal/lysosomal marker LAMP1 and the autophagy protein GABARAPL1. Mutant Stbd1 lacking the N-terminal hydrophobic segment had a diffuse distribution throughout the cell. Point mutations in the CBM20 domain did not change the perinuclear localization of Stbd1, but glycogen was no longer concentrated in this compartment. Stable overexpression of glycogen synthase in Rat1WT4 cells resulted in accumulation of glycogen as massive perinuclear deposits, where a large fraction of the detectable Stbd1 co-localized. Starvation of Rat1WT4 cells for glucose resulted in dissipation of the massive glycogen stores into numerous and much smaller glycogen deposits that retained Stbd1. In vitro, in cells, and in animal models, Stbd1 consistently tracked with glycogen. We conclude that Stbd1 is involved in glycogen metabolism by binding to glycogen and anchoring it to membranes, thereby affecting its cellular localization and its intracellular trafficking to lysosomes. 相似文献
123.
Abstract Pseudomonas fluorescens EB carries genes for the catabolism of ethylbenzene and 1-phenylethanol on a plasmid. The size of the plasmid as measured by analysis of agarose electrophoresis gels after restriction endonuclease hydrolysis, was 253–267 kb. By treatment with Mitomycin C, mutants of EB strain were obtained bearing a plasmid which had undergone an extensive deletion of about 80 kb. These mutants have lost the ability to grow on ethylbenzene and 1-phenylethanol as well as to synthesize meta-cleavage enzymes. 相似文献
124.
Shiro Tabata Takeshi Ide Yasuyoshi Umemura Kenzo Torri 《Biochimica et Biophysica Acta (BBA)/General Subjects》1984,797(2):231-238
α-Glucosidases or maltases (EC 3.2.1.20) were purified to electrophoretic homogeneity from a respective strain of Sacchromyces cerevisiae which carries a single MAL gene, either MALα, MALβ or MALγ, using gluconate-Sepharose affinity chromography and isoelectrofocusing. Of these maltases, two types of maltase were obtained from the MALγ strain, the pI values of which were 5.6 and 5.9. From the MALα and MALβ strain was obtained only one type of maltase with the pI at 5.6 which was identical to one of the maltases from the MALγ strain. These four maltases possessed the same properties, except for pI. They were monomers with molecular weights of between 66 000 and 67 000. With regard to the substrate specificity, they hydrolyzed maltose and sucrose exclusively but not α-methulglucoside nor maltooligosaccharide. They did not differ in immunological properties. 相似文献
125.
126.
127.
128.
129.
《Current biology : CB》2020,30(24):4826-4836.e7
130.