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991.
Zinc binding to peptide analogs of the structural zinc site in alcohol dehydrogenase: Implications for an entatic state 总被引:1,自引:0,他引:1
Bergman T Zhang K Palmberg C Jörnvall H Auld DS 《Cellular and molecular life sciences : CMLS》2008,65(24):4019-4027
Zinc binding to the peptide replica and analogs to residues 93–115 of horse liver alcohol dehydrogenase (ADH) was examined
by competition of the peptides and the chromophoric chelator 4-(2- pyridylazo)resorcinol for zinc and X-ray absorption fine
structure analysis of the zinc ligands. In the enzyme, zinc is coordinated by four Cys residues. In the peptide replica, zinc
is bound to three Cys and one His residue. A four-Cys zinc coordination is observed only when His is removed, leading to increased
zinc stability. ADH crystal structures reveal that the ε-amino group of the conserved residue Lys323 is within H-bond distance
of the backbone amide oxygens of residues 103, 105 and 108, likely stabilizing the zinc coordination in the enzyme. The peptide
data thus indicate structural strain and increased energy in the zinc-binding site in the protein, characteristic of an entatic
state, implying a functional nature for this zinc site.
Received 3 July 2008; received after revision 11 August 2008; accepted 1 September 2008 相似文献
992.
Muñoz U Bartolomé F Esteras N Bermejo-Pareja F Martín-Requero A 《Cellular and molecular life sciences : CMLS》2008,65(21):3507-3519
It has been proposed that neuroinflammation, among other factors, may trigger an aberrant neuronal cell cycle re-entry leading
to neuronal death. Cell cycle disturbances are also detectable in peripheral cells from Alzheimer’s disease (AD) patients.
We previously reported that the anti-inflammatory 15- deoxy-Δ12,14-prostaglandin J
2 (15d-PGJ
2) increased the cellular content of the cyclin-dependent kinase inhibitor p27, in lymphoblasts from AD patients. This work
aimed at elucidating the mechanisms of 15d-PGJ
2-induced p27 accumulation. Phosphorylation, half-life, and the nucleo-cytoplasmic traffic of p27 protein were altered by 15d-PGJ2
by mechanisms dependent on PI3K/Akt activity. 15d-PGJ
2 prevents the calmodulin-dependent Akt overactivation in AD lymphoblasts by blocking its binding to the 85-kDa regulatory
subunit of PI3K. These effects of 15d-PGJ
2 were not mimicked by 9,10-dihydro-15-deoxy-Δ12,14- prostaglandin J
2, suggesting that 15d-PGJ
2 acts independently of peroxisome proliferator-activated receptor γ activation and that the α,β-unsaturated carbonyl group
in the cyclopentenone ring of 15d-PGJ
2 is a requisite for the observed effects.
Received 14 July 2008; received after revision 2 September 2008; accepted 12 September 2008 相似文献
993.
SEA方法及其在$C^3I$系统效能分析中的应用(Ⅲ)——监视模型 总被引:5,自引:0,他引:5
针对SEA方法的要求,提出了评估$C^3I$系统在执行监视任务时的系统效能的三个性能量度(MOP),通过分析$C^3I$系统在执行监视任务时的行为过程和环境特点,结合排队理论,建立了评估$C^3I$系统监视效能的SEA方法模型.利用该模型计算了一个实际$C^3I$系统的监视效能,并对结果进行了简要分析. 相似文献
994.
CCD精密测量系统及其数字信号处理 总被引:8,自引:0,他引:8
杨云志 《系统工程与电子技术》1999,21(6)
介绍了CCD精密测量系统中的信号采集和处理的工作原理,阐述了测量系统和数字信号处理芯片(DSP芯片)在系统中的工作原理,同时还介绍了测量系统的软件工作过程。文中概要介绍了CCD器件的工作原理和CCD器件用于测量中的特点。通过本文,我们可以了解到CCD精密测量系统中DSP芯片的作用。 相似文献
995.
996.
低码率下MPEG—2自适应量化控制策略 总被引:2,自引:1,他引:1
对MPEG-2TM5量化控制策略进行了修正,提出了一种基于宏块直方图特性的自适应量化控制方法.该方法考虑了人眼的视觉特性和编码效率,适应于低码率下的MPEG-2压缩编码,并能有效地提高图象质量. 相似文献
997.
In human patients, blood coagulation disorders often associate with cancer, even in its early stages. Recently, in vitro and in vivo experimental models have shown that oncogene expression, or inactivation of tumour suppressor genes, upregulate genes that
control blood coagulation. These studies suggest that activation of blood clotting, leading to peritumoral fibrin deposition,
is instrumental in cancer development. Fibrin can indeed build up a provisional matrix, supporting the invasive growth of
neoplastic tissues and blood vessels. Interference with blood coagulation can thus be considered as part of a multifaceted
therapeutic approach to cancer.
Received 30 November 2005; received after revision 7 February 2005; accepted 8 February 2006 相似文献
998.
Niimura N Arai S Kurihara K Chatake T Tanaka I Bau R 《Cellular and molecular life sciences : CMLS》2006,63(3):285-300
Neutron diffraction provides an experimental method of directly locating hydrogen atoms in proteins, a technique complimentary to ultra-high-resolution [1, 2] X-ray diffraction. Three different types of neutron diffractometers for biological macromolecules have been constructed in Japan, France and the United States, and they have been used to determine the crystal structures of proteins up to resolution limits of 1.5-2.5 A. Results relating to hydrogen positions and hydration patterns in proteins have been obtained from these studies. Examples include the geometrical details of hydrogen bonds, H/D exchange in proteins and oligonucleotides, the role of hydrogen atoms in enzymatic activity and thermostability, and the dynamical behavior of hydration structures, all of which have been extracted from these structural results and reviewed. Other techniques, such as the growth of large single crystals, the preparation of fully deuterated proteins, the use of cryogenic techniques, and a data base of hydrogen and hydration in proteins, will be described. 相似文献
999.
Based on the classification of bacterial lipolytic enzymes, family I.3 lipase is a member of the large group of Gram-negative
bacterial true lipases. This lipase family is distinguished from other families not only by the amino acid sequence, but also
by the secretion mechanism. Lipases of family I.3 are secreted via the well-known type I secretion system. Like most of proteins
secreted via this system, family I.3 lipases are composed of two domains with distinct yet related functions. Recent years
have seen an increasing amount of research on this lipase family, in terms of isolation, secretion mechanism, as well as biochemical
and biophysical studies. This review describes our current knowledge on the structure-function relationships of family I.3
lipase, with an emphasis on its secretion mechanism.
Received 18 April 2006; received after revision 3 July 2006; accepted 24 August 2006 相似文献
1000.
Kertész A Váradi G Tóth GK Fajka-Boja R Monostori E Sármay G 《Cellular and molecular life sciences : CMLS》2006,63(22):2682-2693
Phosphopeptides interacting with src homology 2 (SH2) domains can activate essential signaling enzymes in vitro. When delivered to cells, they may disrupt protein-protein interactions, thereby influencing intracellular signaling. We
showed earlier that phosphopeptides corresponding to the inhibitory motif of Fcγ receptor IIb and a motif of the Grb2-associated
binder 1 adaptor protein activate SH2-containing tyrosine phosphatase 2 in vitro. To study the ex vivo effects of these peptides, we have now compared different methods for peptide delivery: (i) permeabilization of the target
cells and (ii) the use of cell-permeable vectors, which are potentially able to transport biologically active compounds into
B cells. We found octanoyl-Arg8 to be an optimal carrier for the delivery of phosphopeptides to the cells. With this strategy, the function of cell-permeable
SHP-2-binding phosphopeptides was analyzed. These peptides modulated the protein phosphorylation in B cells in a dose- and
time-dependent manner.
Received 27 July 2006; received after revision 4 September 2006; accepted 18 September 2006 相似文献