全文获取类型
收费全文 | 2837篇 |
免费 | 255篇 |
专业分类
3092篇 |
出版年
2024年 | 3篇 |
2023年 | 30篇 |
2022年 | 63篇 |
2021年 | 88篇 |
2020年 | 65篇 |
2019年 | 63篇 |
2018年 | 85篇 |
2017年 | 61篇 |
2016年 | 116篇 |
2015年 | 193篇 |
2014年 | 195篇 |
2013年 | 259篇 |
2012年 | 305篇 |
2011年 | 242篇 |
2010年 | 178篇 |
2009年 | 158篇 |
2008年 | 154篇 |
2007年 | 160篇 |
2006年 | 134篇 |
2005年 | 100篇 |
2004年 | 85篇 |
2003年 | 79篇 |
2002年 | 47篇 |
2001年 | 15篇 |
2000年 | 17篇 |
1999年 | 15篇 |
1998年 | 6篇 |
1997年 | 10篇 |
1996年 | 7篇 |
1995年 | 3篇 |
1993年 | 6篇 |
1992年 | 20篇 |
1991年 | 6篇 |
1990年 | 11篇 |
1989年 | 6篇 |
1988年 | 9篇 |
1987年 | 8篇 |
1986年 | 8篇 |
1985年 | 5篇 |
1984年 | 6篇 |
1983年 | 8篇 |
1982年 | 7篇 |
1981年 | 5篇 |
1980年 | 7篇 |
1979年 | 3篇 |
1978年 | 7篇 |
1976年 | 4篇 |
1975年 | 9篇 |
1971年 | 3篇 |
1937年 | 3篇 |
排序方式: 共有3092条查询结果,搜索用时 15 毫秒
21.
Specific mitochondrial incorporation of 10 N-nonyl acridine orange (NAO) is demonstrated by subcellular fractionation of rat hepatocytes. Moreover, comparative studies with NAO and rhodamine 123 (Rh 123) prove that acridine orange-derivative uptake is independent of transmembrane mitochondrial potential, a property allowing its utilization for the assessment of mitochondrial membrane mass modifications under various physiological states. Using NAO and Rh 123, we have respectively followed the biosynthesis of mitochondrial membrane and its assembly under a functional state during the L1210 cell cycle. Their evolution occurs in two stages according to a well-defined sequential order. Mitochondrial biogenesis, as revealed by NAO incorporation, occurs essentially in the G1 phase (probably mitochondrion enlargement) but also starts in late S phase (probably mitochondrion division). The increased amount of functional mitochondrial membrane, monitored by Rh 123 uptake, is emphasized in late G1 (prerequisite to DNA synthesis) and during G2M phases (prerequisite to mitosis). This alternative succession of phases displays the existence of a time-lag between the biosynthesis of mitochondrial membrane and its functional organization. Such an analysis confirms the potential of the NAO probe to evaluate mitochondrial membrane mass changes in various biological fields. 相似文献
22.
R Julien J Rathelot P Canioni L Sarda T H Plummer 《Biochimica et biophysica acta》1975,379(1):157-163
1. The amino acid composition of bovine pancreatic lipase is very similar to that of porcine lipase. 2. Bovine lipase possesses a residue of lysine at the N-terminal position and a half cystine or a cysteine at the C-terminal position. 3. Bovine lipase contains two free sulfhydryl groups of different reactivities to 5, 5'-dithiobis-(2-nitrobenzoic) acid. One of these groups is buried in the native conformation of the enzyme and is fully titrated in 1.5 M urea when reaction is performed in the presense of 1 mM EDTA. 相似文献
23.
The molecular mechanisms of toxicity associated with cytoplasmic accumulation of TAR DNA binding protein-43(TDP-43),a pathological feature of many neurodegenera... 相似文献
24.
25.
The Drosophila peptidoglycan recognition protein PGRP-LF blocks PGRP-LC and IMD/JNK pathway activation 总被引:1,自引:0,他引:1
Eukaryotic peptidoglycan recognition proteins (PGRPs) are related to bacterial amidases. In Drosophila, PGRPs bind peptidoglycan and function as central sensors and regulators of the innate immune response. PGRP-LC/PGRP-LE constitute the receptor complex in the immune deficiency (IMD) pathway, which is an innate immune cascade triggered upon Gram-negative bacterial infection. Here, we present the functional analysis of the nonamidase, membrane-associated PGRP-LF. We show that PGRP-LF acts as a specific negative regulator of the IMD pathway. Reduction of PGRP-LF levels, in the absence of infection, is sufficient to trigger IMD pathway activation. Furthermore, normal development is impaired in the absence of functional PGRP-LF, a phenotype mediated by the JNK pathway. Thus, PGRP-LF prevents constitutive activation of both the JNK and the IMD pathways. We propose a model in which PGRP-LF keeps the Drosophila IMD pathway silent by sequestering circulating peptidoglycan. 相似文献
26.
27.
Julien M Verrier B Cerutti M Chappe V Gola M Devauchelle G Becq F 《The Journal of membrane biology》1999,168(3):229-239
Increasing evidence is now accumulating for the involvement of the cystic fibrosis transmembrane conductance regulator (CFTR)
in the control of the outwardly rectifying chloride channel (ORCC). We have examined the sensitivity of ORCC to the sulfonylurea
drug glibenclamide in Hi-5 (Trichoplusia ni) insect cells infected with recombinant baculovirus expressing either wild-type CFTR, ΔF508-CFTR or E. coliβ galactosidase cDNA and in control cells either infected with virus alone or uninfected. Iodide efflux and single channel
patch-clamp experiments confirmed that forskolin and 1-methyl-3-isobutyl xanthine (IBMX) or 7-methyl-1,3 dipropyl xanthine
(DPMX) activate CFTR channels (unitary conductance: 9.1 ± 1.6 pS) only in cells expressing CFTR. In contrast, we identified
4-acetamido-4′-isothiocyanatostilbene-2,2′-disulfonic acid (SITS)-sensitive ORCC in excised membrane patches in any of the
cells studied, with similar conductance (22 ± 2.5 pS at −80 mV; 55 ± 4.1 pS at +80 mV) and properties. In the presence of
500 μm SITS, channel open probability (P
o
) of ORCC was reversibly reduced to 0.05 ± 0.01 in CFTR-cells, to 0.07 ± 0.02 in non-CFTR expressing cells and to 0.05 ± 0.02
in ΔF508-cells. In Hi-5 cells that did not express CFTR, glibenclamide failed to inhibit ORCC activity even at high concentrations
(100 μm), whereas 500 μm SITS reversibly inhibited ORCC. In contrast in cells expressing CFTR or ΔF508, glibenclamide dose dependently (IC50= 17 μm, Hill coefficient 1.2) and reversibly inhibited ORCC. Cytoplasmic application of 100 μm glibenclamide reversibly reduced P
o
from 0.88 ± 0.03 to 0.09 ± 0.02 (wash: P
o
= 0.85 ± 0.1) in CFTR cells and from 0.89 ± 0.05 to 0.08 ± 0.05 (wash: P
o
= 0.87 ± 0.1) in ΔF508 cells. In non-CFTR expressing cells, glibenclamide (100 μm) was without effect on P
o
(control: P
o
= 0.89 ± 0.09, glib.: P
o
= 0.86 ± 0.02; wash: P
o
= 0.87 ± 0.05). These data strongly suggest that the expression of CFTR confers glibenclamide sensitivity to the ORCC in Hi-5
cells.
Received: 23 October 1998/Revised: 29 December 1998 相似文献
28.
Garcia A Cayla X Guergnon J Dessauge F Hospital V Rebollo MP Fleischer A Rebollo A 《Biochimie》2003,85(8):721-726
The reversible phosphorylation of proteins controlled by protein kinases and protein phosphatases is a major mechanism that regulates a wide variety of cellular processes. In contrast to C. elegans, recent studies in mammalian cells have highlighted a major role of serine/threonine protein phosphorylation in apoptosis. To illustrate the importance of dephosphorylation processes in apoptosis, this review will focus on recent studies suggesting that the interaction of the serine/threonine protein phosphatase 1 (PP1) and protein phosphatase 2A (PP2A) with certain regulators of the Bcl-2 family is critically involved in the control of apoptosis. 相似文献
29.
30.
Abstract Using plasma glycoprotein glycans, a correlation was established between their inhibitory capacity of sheep mannose-resistant haemagglutination (MRHA) properties of bovine enterotoxigenic Escherichia coli (ETEC) and their monosaccharide content. Sialic acid seems to be the major component of the inhibitors of adherence of calf ETEC. 相似文献