全文获取类型
收费全文 | 127170篇 |
免费 | 3256篇 |
国内免费 | 934篇 |
出版年
2022年 | 234篇 |
2021年 | 553篇 |
2020年 | 335篇 |
2019年 | 511篇 |
2018年 | 12312篇 |
2017年 | 11029篇 |
2016年 | 8134篇 |
2015年 | 1824篇 |
2014年 | 1701篇 |
2013年 | 2234篇 |
2012年 | 6295篇 |
2011年 | 14675篇 |
2010年 | 13253篇 |
2009年 | 9319篇 |
2008年 | 11357篇 |
2007年 | 12811篇 |
2006年 | 1813篇 |
2005年 | 1902篇 |
2004年 | 2355篇 |
2003年 | 2323篇 |
2002年 | 2148篇 |
2001年 | 1257篇 |
2000年 | 1080篇 |
1999年 | 879篇 |
1998年 | 438篇 |
1997年 | 439篇 |
1996年 | 335篇 |
1995年 | 331篇 |
1994年 | 257篇 |
1993年 | 330篇 |
1992年 | 571篇 |
1991年 | 554篇 |
1990年 | 488篇 |
1989年 | 452篇 |
1988年 | 370篇 |
1987年 | 369篇 |
1986年 | 340篇 |
1985年 | 376篇 |
1984年 | 354篇 |
1983年 | 334篇 |
1981年 | 231篇 |
1979年 | 279篇 |
1978年 | 247篇 |
1977年 | 271篇 |
1976年 | 251篇 |
1975年 | 257篇 |
1974年 | 246篇 |
1973年 | 232篇 |
1972年 | 441篇 |
1971年 | 458篇 |
排序方式: 共有10000条查询结果,搜索用时 375 毫秒
151.
Andrew Leask 《Journal of cell communication and signaling》2010,4(1):73-74
Connective tissue growth factor (CTGF/CCN2) is overexpressed in diabetes. Diabetic rats possess myocardial and cardiomyocyte hypertrophy. In a recent report, Wang and colleagues (Am J Physiol Cell Physiol. 2009 Jul 22. [Epub ahead of print]) show that CCN2 directly mediates cardiomyocyte hypertrophy as well as that induced by high glucose and fatty acid. CCN2 acted via the TrkA receptor. These data are the subject of this commentary, and emphasize that CCN2 may be an excellent target for therapy in diabetes. 相似文献
152.
153.
Physiological and Biochemical Mechanisms Involved in the Response to Abscisic Acid in Maize Coleoptiles 总被引:2,自引:0,他引:2
The role of abscisic acid (ABA) in controlling growth and developmenthas been studied in maize (Zea mays L.) coleoptile segments.Application of ABA reduces the elongation rate by about 50%and affects ion fluxes. In particular, proton extrusion is decreasedwhile potassium efflux is greatly enhanced. Apparently, ABAdoes not: seem to influence calcium influx from the apoplastinto the cytosol, but more likely it influences its efflux.Alteration of cytosolic calcium concentration may also be obtainedby increasing its release from internal stores. This possibilitymight be sustained by the increased hydrolysis of phosphatidylinositolupon ABA application. Change in the balance of ion fluxes shouldresult from regulation of transport mechanisms at the membranelevel and should produce changes in the transmembrane electricalpotential. The H+- ATPase and the ATP-dependent calcium transportactivities are both influenced by the treatment with ABA, 55%and 40%, respectively. Under these conditions [Ca2+]cytand pHcyt can be modified and, as a consequence of their regulation,they may play an important role in mediating the physiologicaland biochemical effects of ABA, acting as second intracellularmessengers.
1Research supported by National Research Council of Italy, SpecialProject RAISA, Sub-Project N. 2, Paper n. 2782. 相似文献
154.
Cassandre Leverrier Giana Almeida Lucia Espinosa-Mu noz Gérard Cuvelier 《Food biophysics》2016,11(3):235-247
This work investigates the impact of structural parameters on the rheological behaviour of apple purees. Reconstructed apple purees from 0 g/100 g up to 2.32 g/100 g of insoluble solids content and varying in particle size were prepared. Three different particle size distributions were obtained by mechanical treatment only, to modify both size and morphology of the particles without modifying the intrinsic rigidity of the cell walls. Rheological measurements showed that the insoluble solids content have a first order effect on the rheological behaviour of the suspensions: three concentrations domains were observed in both dynamic and flow measurements. A model is proposed for each domain. The existence of a weak network between particles is clearly shown over a critical concentration of insoluble solids (cell walls) depending on particle size distribution (semi-diluted domain). In a concentrated domain, particles are on close packing conditions and their apparent volume begin to shrink. Particle size and shape also play an important role on the rheological behaviour of reconstructed apple puree. Due to their irregular shape, cell clusters clog the medium at lower concentration compared to individual cells. 相似文献
155.
156.
I De Carneri 《Parassitologia》1971,13(1):165-167
157.
The cause of the pregnancy condition preeclampsia (PE) is thought to be endothelial dysfunction caused by oxidative stress. As abnormal glucose tolerance has also been associated with PE, we use a fluorinated-mimic of this metabolite to establish whether any oxidative damage to lipids and proteins in the erythrocyte membrane has increased cell membrane permeability. Data were acquired using 19F Dynamic-NMR (DNMR) to measure exchange of 3-fluoro-3-deoxyglucose (3-FDG) across the membrane of erythrocytes from 10 pregnant women (5 healthy control women, and 5 from women suffering from PE). Magnetisation transfer was measured using the 1D selective inversion and 2D EXSY pulse sequences, over a range of time delays. Integrated intensities from these experiments were used in matrix diagonalisation to estimate the values of the rate constants of exchange and membrane permeability. No significant differences were observed for the rate of exchange of 3-FDG and membrane permeability between healthy pregnant women and those suffering from PE, leading us to conclude that no oxidative damage had occurred at this carrier-protein site in the membrane. 相似文献
158.
159.
A general in vitro cloning system was established for four Helleborus species: H. argutifolius, H. foetidus, H. niger and H. orientalis. The plant material was introduced in vitro from axillary buds. A Murashige and Skoog (MS)—based medium (Murashige and Skoog
1962) was used supplemented with 2% (w/v) sucrose, 2-isopentenyladenine (2-iP) and 6-benzylaminopurine (BA). Multiplication
rates depended on the genotype and varied from 1.3 for H. foetidus till 3.8 for H. niger. The first results showed that the rooting phase could be done ex vitro. Rooting was induced by a drench for one week in
a solution of indole-3-butyric acid (IBA -3 mg l−1) and 1-naphthaleneacetic acid (NAA-1 mg l−1) at 5°C. 相似文献
160.