全文获取类型
收费全文 | 271183篇 |
免费 | 17820篇 |
国内免费 | 119篇 |
出版年
2021年 | 2445篇 |
2019年 | 1919篇 |
2018年 | 3832篇 |
2017年 | 3871篇 |
2016年 | 6477篇 |
2015年 | 11195篇 |
2014年 | 11637篇 |
2013年 | 13077篇 |
2012年 | 14589篇 |
2011年 | 11925篇 |
2010年 | 8626篇 |
2009年 | 8013篇 |
2008年 | 9209篇 |
2007年 | 9144篇 |
2006年 | 8659篇 |
2005年 | 15265篇 |
2004年 | 14061篇 |
2003年 | 11666篇 |
2002年 | 7937篇 |
2001年 | 6293篇 |
2000年 | 5128篇 |
1999年 | 5527篇 |
1998年 | 2603篇 |
1997年 | 2049篇 |
1996年 | 1806篇 |
1995年 | 1724篇 |
1992年 | 4837篇 |
1991年 | 4828篇 |
1990年 | 4855篇 |
1989年 | 4544篇 |
1988年 | 4339篇 |
1987年 | 4115篇 |
1986年 | 3743篇 |
1985年 | 3922篇 |
1984年 | 3163篇 |
1983年 | 2661篇 |
1982年 | 2062篇 |
1981年 | 1904篇 |
1980年 | 1787篇 |
1979年 | 2828篇 |
1978年 | 2279篇 |
1977年 | 1978篇 |
1976年 | 1955篇 |
1975年 | 2280篇 |
1974年 | 2527篇 |
1973年 | 2615篇 |
1972年 | 2284篇 |
1971年 | 2102篇 |
1970年 | 1870篇 |
1969年 | 1902篇 |
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
181.
Kolomeyets N. L. Syslonova O. V. Smirnova S. L. Peshkin E. A. Roshchevskaya I. M. 《Journal of Evolutionary Biochemistry and Physiology》2021,57(6):1351-1362
Journal of Evolutionary Biochemistry and Physiology - Changes in bioelectrical impedance of the myocardium and liver were revealed in male Wistar rats chronically exposed to doxorubicin.... 相似文献
182.
Jin Wei Mia Madel Alfajaro Peter C. DeWeirdt Ruth E. Hanna William J. Lu-Culligan Wesley L. Cai Madison S. Strine Shang-Min Zhang Vincent R. Graziano Cameron O. Schmitz Jennifer S. Chen Madeleine C. Mankowski Renata B. Filler Neal G. Ravindra Victor Gasque Fernando J. de Miguel Ajinkya Patil Huacui Chen Craig B. Wilen 《Cell》2021,184(1):76-91.e13
- Download : Download high-res image (212KB)
- Download : Download full-size image
183.
Targeting of many transmembrane proteins to post-Golgi compartments is dependent on cytoplasmically exposed sorting signals. The most widely used signals conform to the tyrosine- or the leucine-based motifs. Both types of signals have been implicated in protein localization to the same intracellular compartments, but previous results from both cell-free experiments and studies of transfected cell lines have indicated that the two types of signals interact with separate components of the sorting machinery. We have overexpressed several transmembrane proteins in stably transfected Madin-Darby canine kidney cells using an inducible promoter system. Overexpression of proteins containing tyrosine- or leucine-based sorting signals resulted in reduced internalization of the transferrin receptor, whereas recycling and polarized distribution was not influenced. Our results indicate that proteins with tyrosine- and leucine-based sorting signals can be transported along common saturable pathways. 相似文献
184.
185.
186.
187.
S Kafert S Luther I B?ll K Wagner A Ganser M Eder 《The Journal of biological chemistry》1999,274(46):33064-33071
To analyze the function of each subunit of the receptor for granulocyte-macrophage colony-stimulating factor (GM-CSF), GMR, we previously generated a single-chain chimeric receptor by fusion of the extracellular and transmembrane domain from the alpha-subunit (alpha-GMR) to the intracellular part of the beta-subunit (beta-GMR) introducing an additional glutamate residue at the fusion site (alpha/beta-GMR). We demonstrated the capacity of alpha/beta-GMR to bind GM-CSF with low affinity and to induce GM-CSF-dependent activation of tyrosine kinase activity and proliferation in transfected Ba/F3 cells. To further compare the functions of wild type and chimeric receptors, we now report that this alpha/beta-GMR is sufficient to mediate morphological changes, expression of alpha(4)- and beta(1)-integrin receptor subunits, and serine-phosphorylation of Akt kinase. To analyze the function of the glutamate residue at the fusion region of alpha/beta-GMR various point mutants changing this amino acid and its position were expressed in Ba/F3 cells. None of these mutants was capable of supporting GM-CSF-dependent proliferation; however, when beta-GMR was coexpressed, GM-CSF mediated short and long term proliferation. Interestingly, some mutants but not alpha/beta-GMR can induce proliferation in the presence of an anti-alpha-GMR antibody. These data demonstrate the significance of a glutamate residue in the transmembrane region of alpha/beta-GMR for ligand-induced receptor activation. 相似文献
188.
Effects of phorbol dibutyrate on M currents and M current inhibition in bullfrog sympathetic neurons 总被引:8,自引:0,他引:8
1. Effects of bath-applied phorbol dibutyrate (PDBu) on M currents (IM) and on the inhibition of IM by muscarine and luteinizing hormone-releasing hormone (LHRH) were recorded in voltage-clamped bullfrog lumbar sympathetic ganglion cells. 2. PDBu (0.1-30 microM) produced a slowly developing, irreversible and partial (less than or equal to 60%) inhibition of IM. This effect was not replicated by 4-alpha-phorbol or by vehicle. 3. After treatment with PDBu, residual IM showed a reduced sensitivity to inhibition by muscarine or LHRH but not by Ba2+. The reduced response to muscarine appeared to result from a 10-fold shift in the concentration dependence for inhibition. 4. PDBu did not clearly reproduce the ability of muscarine to inhibit the slow, Ca-activated K current IAHP or to increase the leak conductance at hyperpolarized potentials. The latter effect of muscarine was enhanced, rather than inhibited, by PDBu. 5. IM and IAHP were not inhibited by 1 mM dibutyryl cyclic AMP or by 20 microM forskolin. 6. It is concluded that activation of protein kinase C, but not protein kinase A, partly replicates the effect of muscarine on frog sympathetic neurons. 相似文献
189.
L Chrobák D Radochová K Smetana F Mat?ja M Kout J Polák P Dít? J Pribrosky I Dvorácková 《Folia haematologica (Leipzig, Germany : 1928)》1980,107(4):628-640
These siblings of a Czech family aged 21, 19 and 6 years, respectively, with congenital dyserythropoietic anemia, type II, (HEMPAS) are reported. In two elder siblings ferrokinetic studies revealed a rapid plasma 59Fe clearance, markedly decreased erythrocyte incorporation and shortened 51Cr red-cell survival. Direct anti-globulin test was found positive in one of them. Further investigations revealed low values of blood plasma cholesterol, total lipids, beta-lipoproteins, beta-carotine and vitamin E and A as well as low values of the prothrombin complex. Liver biopsy demonstrated siderosis and disseminated intravascular coagulation in the liver in both patients. The possible reasons for these humoral aberrations are discussed. 相似文献
190.
Analogs of the molluscan neuropeptide FMRFamide were tested on four different molluscan muscle preparations which show qualitatively different responses to the peptide; the structure-activity relations are basically similar, but not identical. The C-terminal amide and the Arg3 residue are critical for FMRFamide-like activity on all four preparations. In contrast, analogs extended at the N-terminal or with conservative substitutions for the Phe1 or Met2 residue are approximately equipotent to FMRFamide. These structural requirements parallel those for the C-terminal tetrapeptide amide of gastrin. 相似文献