全文获取类型
收费全文 | 2320篇 |
免费 | 145篇 |
国内免费 | 3篇 |
出版年
2023年 | 15篇 |
2022年 | 16篇 |
2021年 | 37篇 |
2020年 | 30篇 |
2019年 | 32篇 |
2018年 | 39篇 |
2017年 | 30篇 |
2016年 | 80篇 |
2015年 | 113篇 |
2014年 | 143篇 |
2013年 | 162篇 |
2012年 | 193篇 |
2011年 | 210篇 |
2010年 | 109篇 |
2009年 | 104篇 |
2008年 | 143篇 |
2007年 | 152篇 |
2006年 | 132篇 |
2005年 | 127篇 |
2004年 | 79篇 |
2003年 | 111篇 |
2002年 | 83篇 |
2001年 | 7篇 |
2000年 | 8篇 |
1998年 | 20篇 |
1997年 | 19篇 |
1996年 | 10篇 |
1995年 | 11篇 |
1994年 | 8篇 |
1993年 | 18篇 |
1992年 | 14篇 |
1991年 | 10篇 |
1990年 | 12篇 |
1989年 | 12篇 |
1988年 | 12篇 |
1987年 | 12篇 |
1986年 | 12篇 |
1985年 | 10篇 |
1984年 | 9篇 |
1983年 | 12篇 |
1982年 | 12篇 |
1981年 | 6篇 |
1980年 | 10篇 |
1979年 | 17篇 |
1978年 | 11篇 |
1977年 | 6篇 |
1975年 | 7篇 |
1972年 | 5篇 |
1971年 | 5篇 |
1969年 | 6篇 |
排序方式: 共有2468条查询结果,搜索用时 140 毫秒
91.
92.
Tobias Ruck Stefanie Bock Steffen Pfeuffer Christina B.Schroeter Derya Cengiz Paul Marciniak Maren Lindner Alexander Herrmann Marie Liebmann Stjepana Kovac Lukas Gola Leoni Rolfes Marc Pawlitzki Nils Opel Tim Hahn Udo Dannlowski Thomas Pap Felix Luessi Julian A.Schreiber Bernhard Wünsch Tanja Kuhlmann Guiscard Seebohm Bjrn Tackenberg Patricia Seja Frank Dring Erhard Wischmeyer Achmet Imam Chasan Johannes Roth Luisa Klotz Gerd Meyer zu Hrste Heinz Wiendl Tobias Marschall Stefan Floess Jochen Huehn Thomas Budde Tobias Bopp Stefan Bittner Sven G.Meuth 《Cell research》2022,32(1):72-88
It remains largely unclear how thymocytes translate relative differences in T cell receptor (TCR) signal strength into distinct developmental programs that driv... 相似文献
93.
Normal development and fertility of knockout mice lacking the tumor suppressor gene LRP1b suggest functional compensation by LRP1
下载免费PDF全文
![点击此处可从《Molecular and cellular biology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Marschang P Brich J Weeber EJ Sweatt JD Shelton JM Richardson JA Hammer RE Herz J 《Molecular and cellular biology》2004,24(9):3782-3793
LRP1b and the closely related LRP1 are large members of the low-density lipoprotein receptor family. At the protein level LRP1b is 55% identical to LRP1, a multifunctional and developmentally essential receptor with roles in cargo transport and cellular signaling. Somatic LRP1b mutations frequently occur in non-small cell lung cancer and urothelial cancers, suggesting a role in the modulation of cellular growth. In contrast to LRP1, LRP1b-deficient mice develop normally, most likely due to its restricted expression pattern and functional compensation by LRP1 or other receptors. LRP1b is expressed predominantly in the brain, and a differentially spliced form is present in the adrenal gland and in the testis. Despite the presence of a potential furin cleavage site and in contrast to LRP1, immunoblotting for LRP1b reveals the presence of a single 600-kDa polypeptide species. Using a yeast two-hybrid approach, we have identified two intracellular proteins, the postsynaptic density protein 95 and the aryl hydrocarbon receptor-interacting protein, that bind to the intracellular domain of LRP1b. In addition, we have found several potential ligands that bind to the extracellular domain. Analysis of LRP1b knockout mice may provide further insights into the role of LRP1b as a tumor suppressor and into the mechanisms of cancer development. 相似文献
94.
Rössler J Stolze I Frede S Freitag P Schweigerer L Havers W Fandrey J 《Journal of cellular biochemistry》2004,93(1):153-161
The glycoprotein hormone Erythropoietin (EPO) stimulates red cell production and maturation. EPO is produced by the kidneys and the fetal liver in response to hypoxia (HOX). Recently, EPO expression has also been observed in the central nervous system where it may be neuroprotective. It remained unclear, however, whether EPO is expressed in the peripheral nervous system and, if so, whether a neuronal phenotype is required for its regulation. Herein, we report that EPO expression was induced by HOX and a HOX mimetic in two cell lines derived from neuroblastoma (NB), a tumor of the peripheral nervous system. Both cell lines with inducible EPO expression, SH-SY5Y and Kelly cells, expressed typical neuronal markers like neuropeptide Y (NPY), growth-associated protein-43 (GAP-43), and neuron-specific enolase (ENO). NB cells with a more epithelial phenotype like SH-SHEP and LAN-5 did not show HOX inducible EPO gene regulation. Still, oxygen sensing and up-regulation of hypoxia-inducible factor-1 (HIF-1) were intact in all cell lines. We found that CpG methylation of the HIF binding site (HBS) in the EPO gene 3' enhancer was only present in the SH-SHEP and LAN-5 cells but not in SH-SY5Y and Kelly cells with regulated EPO expression. The addition of recombinant EPO to all NB cells, both under normoxic and hypoxic conditions, had no effect on cell proliferation. We conclude that the ability to respond to HOX with an increase in EPO expression in human NB may depend on CpG methylation and the differentiation status of these embryonic tumor cells but does not affect the proliferative characteristics of the cells. 相似文献
95.
96.
A dichloromethane and a methanol extract of the liverwort Bazzania trilobata showed antifungal activity against the phytopathogenic fungi Botrytis cinerea, Cladosporium cucumerinum, Phythophthora infestans, Pyricularia oryzae and Septoria tritici. Bioautography on thin-layer chromatograms was used to isolate six antifungal sesquiterpenes: 5- and 7-hydroxycalamenene, drimenol, drimenal, viridiflorol, gymnomitrol and three bisbibenzyls: 6 ',8'-dichloroisoplagiochin C, isoplagiochin D and 6'-chloroisoplagiochin D. Furthermore we report the isolation of gymnomitr-8(12)-en-4-one and the new coumarin 7,8-dihydroxycoumarin-7-O-beta-D-glucuronide. Their structures have been elucidated based on extensive NMR spectral evidence. 相似文献
97.
Stable haploid poplar callus lines from immature pollen culture 总被引:3,自引:0,他引:3
Embryogenesis and plant regeneration have been obtained from isolated immature pollen of two poplar hybrids ( Populus nigra L. × hybrid 'Aue1' and 'Aue2'). In total, 1487 calli or embryos, respectively, larger than 1 mm were generated in a 2-year study. By using a cytokinin containing induction medium, on average 19 calli per responsive immature catkin were formed. Additional supplementation with auxin in 2002 increased the frequency to 72 calli per catkin. Microsatellite marker analyses confirmed haploid origin in most regenerants studied. So far six out of eight obtained regenerative callus lines have maintained their haploid level up to 24 months of development. A number of haploid and doubled haploid plants of different lines are available and have been transferred to soil. 相似文献
98.
Springer J Wagner S Subramamiam A McGregor GP Groneberg DA Fischer A 《Regulatory peptides》2004,118(1-2):19-23
Brain-derived neurotrophic factor (BDNF) is a key modulator during the development of jugular and nodose ganglia neurons, which represent the origin of a large proportion of the sensory innervation of the lung. It belongs to the family of neurotrophins, which have been shown to induce the expression of tachykinins. To assess the interactions of BDNF and the tachykinin neurokinin A (NKA) in small pulmonary vessels, BDNF-transgenic mice were examined for tachykinin contents in the airways, heart, trigeminal ganglion and jugular and nodose ganglion complex (JNC) using reverse phase HPLC (rpHPLC) and radioimmunoassay. BDNF-overexpression led to increased NKA levels in the heart and the JNC, whereas only slightly enhanced levels in the trigeminal ganglion were detected. Lower NKA levels were found in the lung. To assess vasoreactivity in small arteries, precision cut lung slices were subjected to videomorphometry and the response to NKA was examined, which showed significantly stronger effects in the BDNF-transgenic mice, while NK-2 receptor mRNA expression, assayed by real-time RT-PCR, was reduced. In conclusion, BDNF-overexpression results in decreased levels of NKA in the lung with subsequently increased NKA-sensitivity of small arteries. These findings point to a modulatory role of neurotrophins in small respiratory vessel tone regulation. 相似文献
99.
Innocenti A Antel J Wurl M Scozzafava A Supuran CT 《Bioorganic & medicinal chemistry letters》2004,14(22):5703-5707
Among the 14 human isozymes of carbonic anhydrase (CA, EC 4.2.1.1) presently known, the cytosolic hCA II is the most active and plays a host of physiological functions, whereas the mitochondrial hCA V is unique due to its role in several biosynthetic reactions. An inhibition study of these isozymes with a series of sulfonamides is reported here, with the scope to detect lead molecules for the design of isozyme-specific CA inhibitors (CAIs) targeting the mitochondrial isoform. Indeed, recently it has been shown that CA V is a novel target for the drug design of anti-obesity agents among others. Compounds included in this study were mainly ortho-, meta-, and para-substituted-benzenesulfonamides, together with several halogeno-substituted sulfanilamides and disubstituted-benzene-1,3-disulfonamide derivatives. Isozyme V showed an inhibition profile with these sulfonamides different of that of hCA II. Thus, IC(50) values in the range of 80 nM to 74 microM against hCA II, and 0.78-63.7 microM against hCA V with these derivatives have been obtained. Only one compound, 2-carboxymethyl-benzenesulfonamide, was more active against hCA V over hCA II (selectivity ratio of 1.39), whereas all other derivatives investigated here were much better hCA II inhibitors (selectivity ratios CA II/CA V in the range of 0.0008-0.73) than hCA V inhibitors. 相似文献
100.