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351.
该文应用连续介质力学理论建立了与蒸汽注入过程相关的热-流-变形耦合问题的基本数学模型;应用全隐式顺序Galerkin有限元数值解方案,对注蒸汽井的热-流体-变形耦合过程进行了数值模拟。结果表明,由于低渗透页岩地层流体高温膨胀导致的超高孔隙压力,有可能产生拉张应力,严重时会导致地层破裂。 相似文献
352.
Tanja Wilke Wilko H. Ahlrichs Olaf R.P. Bininda-Emonds 《Journal of Natural History》2019,53(7-8):413-423
The morphology of soft-bodied rotifers, including those of Synchaeta spp, can be strongly affected by preparation artefacts including contraction and deformation. The long-standing, valid species Synchaeta monopus is known exclusively from ethanol- or formaldehyde-preserved material and no live specimens of it have ever been described. Although this alone is cause for concern, we could also reproduce unique characteristics diagnostic for this species (e.g. the swollen body and the rudimental foot) by subjecting specimens of Synchaeta pectinata to the preservation conditions under which it was first described. This proxy experiment and comparisons to other Synchaeta species indicate that literature occurrences of S. monopus likely represent preserved and deformed specimens of Synchaeta cecilia or other marine species of Synchaeta, thereby highlighting the importance of thorough morphological investigations of the habitus using live specimens and of features that are unaffected by preservation (e.g. the trophi). We therefore recommend that S. monopus be listed as a species inquirenda until topotypes are examined. Furthermore, in ecological studies including rotifers, where the examination of preserved material is often unavoidable, we stress that light-microscopical images of the habitus and trophi of the specimens minimally be included to facilitate independent verification of the species assignments. 相似文献
353.
R. P. Massengo-Tiassé J. E. Cronan 《Cellular and molecular life sciences : CMLS》2009,66(9):1507-1517
The enoyl-acyl carrier protein reductase (ENR) is the last enzyme in the fatty acid elongation cycle. Unlike most enzymes
in this essential pathway, ENR displays an unusual diversity among organisms. The growing interest in ENRs is mainly due to
the fact that a variety of both synthetic and natural antibacterial compounds are shown to specifically target their activity.
The primary anti-tuberculosis drug, isoniazid, and the broadly used antibacterial compound, triclosan, both target this enzyme.
In this review, we discuss the diversity of ENRs, and their inhibitors in the light of current research progress.
Received 3 November 2008; received after revision 5 December 2008; accepted 8 December 2008 相似文献
354.
Wolfs JL Comfurius P Bekers O Zwaal RF Balasubramanian K Schroit AJ Lindhout T Bevers EM 《Cellular and molecular life sciences : CMLS》2009,66(2):314-323
The exposure of phosphatidylserine (PS) at the cell surface plays a critical role in blood coagulation and serves as a macrophage
recognition moiety for the engulfment of apoptotic cells. Previous observations have shown that a high extracellular [K+] and selective K+ channel blockers inhibit PS exposure in platelets and erythrocytes. Here we show that the rate of PS exposure in erythrocytes
decreases by ~50% when the intracellular [K+] increases from 0 to physiological concentrations. Using resealed erythrocyte membranes, we further show that lipid scrambling
is inducible by raising the intracellular [Ca2+] and that K+ ions have a direct inhibitory effect on this process. Lipid scrambling in resealed ghosts occurs in the absence of cell shrinkage
and microvesicle formation, processes that are generally attributed to Ca2+-induced lipid scrambling in intact erythrocytes. Thus, opening of Ca2+-sensitive K+ channels causes loss of intracellular K+ that results in reduced intrinsic inhibitory effect of these ions on scramblase activity.
Received 11 September 2008; received after revision 17 October 2008; accepted 27 October 2008 相似文献
355.
J. Kim D. C. Han J. M. Kim S. Y. Lee S. J. Kim J. R. Woo J. W. Lee S.-K. Jung K. S. Yoon H. G. Cheon S. S. Kim S. H. Hong B.-M. Kwon 《Cellular and molecular life sciences : CMLS》2009,66(10):1766-1781
Indenone KR-62776 acts as an agonist of PPARγ without inducing obesity in animal models and cells. X-ray crystallography reveals
that the indenone occupies the binding pocket in a different manner than rosiglitazone. 2-Dimensional gel-electrophoresis
showed that the expression of 42 proteins was altered more than 2.0-fold between KR-62776- or rosiglitazone-treated adipocyte
cells and control cells. Rosiglitazone down-regulated the expression of ERK1/2 and suppressed the phosphorylation of ERK1/2
in these cells. However, the expression of ERK1/2 was up-regulated in KR-62776-treated cells. Phosphorylated ERK1/2, activated
by indenone, affects the localization of PPARγ, suggesting a mechanism for indenone-inhibition of adipogenesis in 3T3-L1 preadipocyte
cells. The preadipocyte cells are treated with ERK1/2 inhibitor PD98059, a large amount of the cells are converted to adipocyte
cells. These results support the conclusion that the localization of PPARγ is one of the key factors explaining the biological
responses of the ligands.
Received 04 March 2009; received after revision 13 March 2009; accepted 17 March 2009 相似文献
356.
Functions and pathologies of BiP and its interaction partners 总被引:1,自引:1,他引:0
J. Dudek J. Benedix S. Cappel M. Greiner C. Jalal L. Müller R. Zimmermann 《Cellular and molecular life sciences : CMLS》2009,66(9):1556-1569
The endoplasmic reticulum (ER) is involved in a variety of essential and interconnected processes in human cells, including
protein biogenesis, signal transduction, and calcium homeostasis. The central player in all these processes is the ER-lumenal
polypeptide chain binding protein BiP that acts as a molecular chaperone. BiP belongs to the heat shock protein 70 (Hsp70)
family and crucially depends on a number of interaction partners, including co-chaperones, nucleotide exchange factors, and
signaling molecules. In the course of the last five years, several diseases have been linked to BiP and its interaction partners,
such as a group of infectious diseases that are caused by Shigella toxin producing E. coli. Furthermore, the inherited diseases Marinesco-Sj?gren syndrome, autosomal dominant polycystic liver disease, Wolcott-Rallison
syndrome, and several cancer types can be considered BiP-related diseases. This review summarizes the physiological and pathophysiological
characteristics of BiP and its interaction partners.
Received 20 November 2008; received after revision 09 December 2008; accepted 12 December 2008 相似文献
357.
Dynamic protein methylation in chromatin biology 总被引:1,自引:1,他引:0
358.
A. Beqqali W. van Eldik C. Mummery R. Passier 《Cellular and molecular life sciences : CMLS》2009,66(5):800-813
Studies on identification, derivation and characterization of human stem cells in the last decade have led to high expectations
in the field of regenerative medicine. Although it is clear that for successful stem cell-based therapy several obstacles
have to be overcome, other opportunities lay ahead for the use of human stem cells. A more immediate application would be
the development of human models for cell-type specific differentiation and disease in vitro. Cardiomyocytes can be generated from stem cells, which have been shown to follow similar molecular events of cardiac development
in vivo. Furthermore, several monogenic cardiovascular diseases have been described, for which in vitro models in stem cells could be generated. Here, we will discuss the potential of human embryonic stem cells, cardiac stem
cells and the recently described induced pluripotent stem cells as models for cardiac differentiation and disease.
Received 07 August 2008; received after revision 26 September 2008; accepted 03 October 2008 相似文献
359.
G. M. C. Janssen P. Schwertman T. A. T. Wanga R. S. Jahangir Tafrechi P. J. A. van den Broek A. K. Raap 《Cellular and molecular life sciences : CMLS》2009,66(4):721-730
Cytoplasmic translation is under sophisticated control but how cells adapt its rate to constitutive loss of mitochondrial
oxidative phosphorylation is unknown. Here we show that translation is repressed in cells with the pathogenic A3243G mtDNA
mutation or in mtDNA-less ρ0 cells by at least two distinct pathways, one transiently targeting elongation factor eEF-2 and the other initiation factor
eIF-2α constitutively. Under conditions of exponential cell growth and mammalian target of rapamycin (mTOR) activation, eEF-2
becomes transiently phosphorylated by an AMP-activated protein kinase (AMPK)-dependent pathway, especially high in mutant
cells. Independent of AMPK and mTOR, eIF-2α is constitutively phosphorylated in mutant cells, likely a signature of endoplasmic
reticulum (ER)-stress response induced by the loss of oxidative phosphorylation. While the AMPK/eEF-2K/eEF-2 pathway appears
to function in adaptation to physiological fluctuations in ATP levels in the mutant cells, the ER stress signified by constitutive
protein synthesis inhibition through eIF-2α-mediated repression of translation initiation may have pathobiochemical consequences.
Received 29 October 2008; received after revision 11 December 2008; accepted 16 December 2008 相似文献
360.
A. Shukla P. Chaurasia S. R. Bhaumik 《Cellular and molecular life sciences : CMLS》2009,66(8):1419-1433
Methylation of lysine residues of histones is associated with functionally distinct regions of chromatin, and, therefore,
is an important epigenetic mark. Over the past few years, several enzymes that catalyze this covalent modification on different
lysine residues of histones have been discovered. Intriguingly, histone lysine methylation has also been shown to be cross-regulated
by histone ubiquitination or the enzymes that catalyze this modification. These covalent modifications and their cross-talks
play important roles in regulation of gene expression, heterochromatin formation, genome stability, and cancer. Thus, there
has been a very rapid progress within past several years towards elucidating the molecular basis of histone lysine methylation
and ubiquitination, and their aberrations in human diseases. Here, we discuss these covalent modifications with their cross-regulation
and roles in controlling gene expression and stability.
Received 24 September 2008; received after revision 21 November 2008; accepted 28 November 2008 相似文献