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991.
HA Neumann 《Canadian Metallurgical Quarterly》1998,24(7):765-770
(2S,4S)-2-Amino-4-(4,4-diphenylbut-1-yl)-pentane-1,5-dioic acid 1m, is a novel metabotropic glutamate receptor (mGluR) antagonist with insignificant ionotropic affinity. It is selective antagonist of negatively-coupled cAMP-linked mGluRs with no effect on phosphoinositide coupled mGluRs. A series of 4-substituted glutamic acid analogues were prepared and it was found that compound 1k is tenfold more potent than 1m. Compound 1k has neither significant affinity for ionotropic glutamate receptors nor group 1 and 3 metabotropic receptors. 相似文献
992.
OBJECTIVE: To assess, in a clinical setting, the comparative values of conventional criteria used in the diagnosis of central nervous system (CNS) involvement in Trypanosoma brucei gambiense sleeping sickness: white cell count (WCC) in cerebrospinal fluid (CSF) > 5 x 10(6) cells/l; total protein concentration in CSF > 40 mg/100 ml); evidence of trypanosomes in CSF following double centrifugation (DC). METHOD: In vitro culture of CSF was used as the gold standard. RESULTS: The study showed that WCC is, by itself, as sensitive for the diagnosis of the CNS involvement as the usually recommended combination of three conventional criteria. The specificity of WCC is improved while the sensitivity is reduced when the cut-off point is set at a higher value (WCC > 10 X 10(6)/l). CONCLUSION: In poorly equipped laboratories, the diagnosis of CNS involvement in patients with confirmed systemic infection should be based only on the WCC. However, a pilot study is needed to assess the feasibility and reliability of the WCC handled by 'front line' personnel, for different cut-off values. 相似文献
993.
Epidermal growth factor (EGF) and transforming growth factor alpha (TGF-alpha) are structurally related growth factors that exert their biological actions by binding to the same cell-surface receptor, EGF receptor. However, in chicken cells, human EGF binds with approximately 100-fold lower affinity than human TGF-alpha. In a previous study, we localized EGF/TGF-alpha receptor immunohistochemically in the granulosa and theca of the developing follicles of laying hens. We have also shown that TGF-alpha binds to cell-surface receptors of the granulosa cells. The present study characterizes the nature of the EGF/TGF-alpha receptor. Immunoprecipitation of receptor proteins from cultured granulosa cells with an anti-EGF receptor antibody (12E) shows the expression of a 170-kDa receptor protein. The expression of the receptor protein decreases with follicular enlargement between the F3 and F1. Incubation of the cells with [125I]TGF-alpha followed by cross-linking with bis(sulphosuccinimidyl)suberate showed that TGF-alpha binds a similar (170 kDa) receptor protein immunoprecipitated with the 12E anti-EGF receptor antibody. The binding of TGF-alpha to granulosa cells caused receptor protein oligomerization, yielding the monomeric (170 kDa) and dimeric (340 kDa) protein forms. Oligomerization seemed to favour the formation of the dimeric rather than the monomeric form. Culturing granulosa cells with luteinizing hormone or follicle-stimulating hormone increased the expression of both monomer and dimer forms of the receptor proteins compared with the control. Western blotting analysis with anti-phosphotyrosine antibody revealed that the lysates of TGF-alpha-stimulated cells express phosphotyrosine-containing receptor proteins of 170 kDa and 340 kDa. The results show that chicken granulosa cells express the 170-kDa EGF/TGF-alpha receptor protein, which dimerizes on binding to TGF-alpha, suggesting that the receptor protein may be involved in the signal transduction of TGF-alpha actions in the chicken granulosa cells. 相似文献
994.
Mark Turner 《突发事故与危机管理杂志》1995,3(1):1-11
This article examines the increasing incidence of kidnapping in the Philippines between 1991 to 1993. The context of the kidnappings is analysed to demonstrate why they constituted a crisis. The incidence of the crime is investigated with particular reference to who was being kidnapped and to regional variations, theories and facts about the alleged perpetrators being delineated before outlining the various ways in which official agencies, non-governmental organizations and individuals have responded to the crisis. The article concludes with some observations on the possibilities and problems of managing successful responses to such crises. 相似文献
995.
High-power, high-temperature operation of GaInAsSb-AlGaAsSbridge-waveguide lasers emitting at 1.9 μm
Choi H.K. Turner G.W. Connors M.K. Fox S. Dauga C. Dagenais M. 《Photonics Technology Letters, IEEE》1995,7(3):281-283
Ridge-waveguide lasers emitting at ~1.9 μm have been fabricated from a multiple-quantum-well heterostructure with an active region consisting of five GaInAsSb wells and six AlGaAsSb barriers. At room temperature, single-ended cw output power as high as 100 mW has been obtained. The maximum cw operating temperature is 130°C, with a characteristic temperature of 85 K between 20 and 80°C 相似文献
996.
997.
998.
Turner Samuel M.; Beidel Deborah C.; Larkin Kevin T. 《Canadian Metallurgical Quarterly》1986,54(4):523
Compared the level of physiological reactivity and frequency of negative cognitions in 26 nonclinic, socially anxious (SA) Ss (mean age 20.8 yrs), 17 clinic SA patients (mean age 40.8 yrs), and 26 nonsocially anxious (NSA) Ss (mean age 22.0 yrs) to investigate the consistency of cognitive and physiological reactivity in the assessment of social anxiety. A social interaction self-statement test served as the cognitive measure. Physiological reactivity was monitored continuously throughout Ss' completion of the following behavioral tasks: an unstructured interpersonal interaction with an opposite-sex confederate, a similar interaction with a same-sex confederate, and an impromptu talk on a topic selected by the S. The clinic and nonclinic samples of SA Ss differed significantly from the NSA Ss in level of physiological reactivity and type of cognition. There were no significant differences between the 2 anxious groups. The results indicate that both thoughts and physiological reactivity were influenced by situational parameters. (17 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
999.
Binding-protein-dependent transport systems in Gram-negative bacteria are multicomponent systems in which a soluble periplasmic binding protein of high substrate binding affinity establishes the major substrate recognition site. Usually, there are two membrane proteins which are thought to interact with the substrate loaded form of the binding protein to allow transport of substrate to occur. Transport is against the concentration gradient and needs energization by an ATP hydrolyzing polypeptide. Overall transport is considered mainly unidirectional owing to the high energy of ATP hydrolysis coupled to transport. We dissected the overall transport process into three individual steps: (i) reversible binding of substrate to the binding protein; (ii) reversible binding of the binding protein to the membrane components forming the translocation complex; (iii) irreversible transport of substrate through the membrane and dissociation of the binding protein from the complex. Two models were considered. In the first, only the substrate-loaded binding protein interacts with the membrane components, while in the second model both the loaded and the unloaded form of the binding protein interact with the membrane components. The mathematical analysis of the second model revealed that the substrate concentration KM at half-maximal rate of transport approaches KD of the binding protein when the last step of transport becomes low and when the concentration of binding protein in the periplasm becomes large. This is usually observed in real systems. Under the same conditions, in model 1 KM approaches zero and is hence considerably smaller than KD. This has never been observed in any real system. In addition, the dependence of the overall rate of transport on the concentration of binding protein in the periplasm follows a sigmoidal curve only when model 2 is considered. The sigmoidal behavior becomes more pronounced when the substrate concentration is low and it is less pronounced when the last step in overall transport is low. This phenomenon has been observed with the Escherichia coli maltose transport system. Thus, at least for the maltose transport system, it seems likely that both the loaded and the unloaded forms of the binding protein interact with the membrane components. We propose that this should generally be considered in binding-protein-dependent transport systems. 相似文献
1000.