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11.
Kang Hai-gui 《水动力学研究与进展(B辑)》1994,(2)
HYDRODYNAMIC FORCE ON SMOOTH HORIZONTAL CYLINDER IN UNIFORM OSCILLATORY FLOWHYDRODYNAMICFORCEONSMOOTHHORIZONTALCYLINDERINUNIF... 相似文献
12.
13.
HJ Lee HK Ha MH Kim YK Jeong PN Kim MG Lee JS Kim DJ Suh SG Lee YI Min YH Auh 《Canadian Metallurgical Quarterly》1997,169(2):517-520
OBJECTIVE: The purpose of this study was to evaluate ERCP and CT findings of ectopic drainage of the common bile duct into the duodenal bulb. CONCLUSION: Although rare, the diagnosis of ectopic drainage of the common bile duct into the duodenal bulb is important to prevent inadvertent damage during biliary tract or gastric surgery and to clarify the cause of chronic peptic ulcers. 相似文献
14.
The present study determined tumorigenicity, tumor classification and DNA damage induced in infant mice by benzo[a]pyrene (B[a]P) or Manufactured Gas Plant (MGP) residues after a single exposure. Male and female B6C3F1 mice were exposed to B[a]P or MGP residue from a single environmental site (MGP-4) and males were also exposed to MGP residue composite from seven different sites (MGP-M7). At 26, 39 and 52 weeks after exposure tumorigenesis was assessed in lung, forestomach and liver. Formation and persistence of DNA adducts were quantified by 32P-postlabeling. Exposure of males to B[a]P induced liver tumors in a dose and time dependent manner. MGP induced more advanced tumors than B[a]P. Only a single liver tumor was found in MGP-4 treated females. No forestomach and few pulmonary adenomas were induced in males or females. MGP-4, MGP-M7 or B[a]P induced DNA adducts in males and females. Adducts in liver, lung and forestomach peaked on different days and decreased at different rates. At 24 h post-exposure, no significant differences in initial DNA adduct levels occurred in males and females exposed to MGP-4 or B[a]P. Lack of DNA damage (adducted DNA) did not account for non-responsiveness of lung and forestomach in B6C3F1 genders as well as in liver in females. MGP tumorigenicity could not be accounted for solely by B[a]P content nor did it reflect additivity of B[a]P and other carcinogenic polycyclic aromatic hydrocarbons (PAHs) in MGP. Synergy among MGP-PAHs, presence of unidentified carcinogens and/or promoters in MGP may account for MGP potency. The B6C3F1 infant male model is a convenient and rapid assay for assessing MGP liver tumorigenicity and potency. 相似文献
15.
Kang W.P. Wisitsora-at A. Davidson J.L. Kerns D.V. 《Electron Device Letters, IEEE》1998,19(10):379-381
A boron-doped diamond field emitter diode with ultralow turn-on voltage and high emission current is reported. The diamond field emitter diode structure with a built-in cap was fabricated using molds and electrostatic bonding techniques. The emission current versus anode voltage of the capped diamond emitter diode with boron doping, sp2 content, and vacuum thermal electric (VTE) treatment shows a very low turn-on voltage of 2 V. A high emission current of 1 μA at an anode voltage of less than 10 V can be obtained from a single diamond tip. The turn-on voltage is significantly lower than comparable silicon field emitters 相似文献
16.
An increased production of reactive oxygen species is thought to be critical to the pathogenesis of Parkinson's disease. At autopsy, patients with either presymptomatic or symptomatic Parkinson's disease have a decreased level of glutathione in the substantia nigra pars compacta. This change represents the earliest index of oxidative stress in Parkinson's disease discovered to this point. This study compares the sensitivity of dopaminergic and nondopaminergic neurons in dissociated mesencephalic cultures to the depletion of glutathione. We have found that dopaminergic neurons are more resistant to the toxicity of glutathione depletion than nondopaminergic neurons. The possibility that dopaminergic neurons have a higher baseline glutathione level than nondopaminergic neurons is suggested by measurements of levels of cellular glutathione in a parallel system of immortalized embryonic dopaminergic and nondopaminergic cell lines. We also examined the role of glutathione in 1-methyl-4-phenylpyridinium toxicity. Decreasing the glutathione level of dopaminergic neurons potentiates their susceptibility to 1-methyl-4-phenylpyridinium toxicity, although 1-methyl-4-phenylpyridinium does not deplete glutathione from primary mesencephalic cultures. Our data suggest that although a decreased glutathione content is not likely to be the sole cause of dopaminergic neuronal loss in Parkinson's disease, decreased glutathione content may act in conjunction with other factors such as 1-methyl-4-phenylpyridinium to cause the selective death of dopaminergic neurons. 相似文献
17.
PURPOSE: The purpose of this study was to assess the value of 3-dimensional sonography in the diagnosis of congenital müllerian duct anomalies, which cause infertility, preterm labor, and first trimester abortion. METHODS: A prospective study was undertaken in which 40 patients with histories of repeated spontaneous abortions or infertility were first examined using conventional 2-dimensional sonography or hysterosalpingography. Three-dimensional transvaginal sonography was then performed. RESULTS: Twenty-eight women had müllerian duct abnormalities, and 12 women had normal uterine anatomy. Müllerian duct defects detected in this study were unicornuate uterus (3), bicornuate uterus (3), complete or partial septate uterus (12), arcuate uterus (9), and didelphic uterus (1). The diagnosis of müllerian duct anomalies in these patients was confirmed by laparoscopic and/or hysteroscopic examinations. Three-dimensional sonography demonstrated all congenital uterine abnormalities with a sensitivity and specificity of 100%. Separate uterus and bicornuate uterus could be correctly diagnosed using 3-dimensional sonography in 11 (92%) of 12 cases and 3 (100%) of 3 cases, respectively. These 2 abnormalities were commonly confused with each other using hysterosalpingography and conventional sonography. CONCLUSIONS: Three-dimensional sonography with image reconstruction is less expensive and less invasive than hysterosalpingography for the assessment of uterine anatomy and diagnosis of müllerian duct abnormalities. The ability to visualize both the uterine cavity and the myometrium on a 3-dimensional scan facilitates the diagnosis of uterine anomalies and enables the differentiation of septate from bicornuate uteri for preoperative surgical planning. 相似文献
18.
JM Derlon MC Petit-Taboué F Chapon V Beaudouin MH No?l C Creveuil P Courtheoux JP Houtteville 《Canadian Metallurgical Quarterly》1997,40(2):276-87; discussion 287-8
OBJECTIVE: The object of the present study was to identify metabolic differences between low-grade astrocytomas and oligodendrogliomas and to improve their diagnosis and noninvasive assessment, because both types of tumors look very similar from the point of view of clinical and radiological data (as assessed by computed tomography and magnetic resonance imaging). METHODS: Before any aggressive treatment, 22 patients with primary low-grade gliomas (astrocytomas in 12 patients and oligodendrogliomas in 10) were investigated with positron emission tomography for both glucose metabolism (18F-fluorodeoxyglucose) and amino acid uptake (11C-L-methylmethionine). An original software that allows a full metabolic analysis of the tumor region of interest (defined from the T1-weighted magnetic resonance image) and compares tumor tissue uptake tracer concentrations with average healthy tissue values has been implemented for data processing. Heterogeneity of each individual tumor has been taken into account and was expressed in histograms, which provided data about the mean and also extreme and intermediate values of tracer concentrations and the way these values are distributed among the full tumor mass. RESULTS: It has been shown that both tumor types exhibit a glucose hypometabolism (slightly more pronounced with astrocytomas), whereas they strongly differ in methionine uptake, which is high in all oligodendrogliomas and either decreased, normal, or moderately increased in astrocytomas. This latter metabolic difference between both tumor populations may be partially explained by their different cell densities. CONCLUSION: This study suggests that despite similar radiological and clinical presentations, these two kinds of low-grade gliomas are metabolically different and could therefore have specific responses to different therapies. Moreover, their in vivo metabolic follow-up with positron emission tomography should rely on different parameters, depending on their histological type; methionine uptake may be more relevant than glucose metabolism in the follow-up of oligodendrogliomas. 相似文献
19.
BACKGROUND: Germ cell tumors (GCTs) and their metastases may be found in numerous sites that are accessible to cytologic sampling, and many are responsive to chemotherapy. METHODS: The authors reviewed 20 examples of GCT cytology from 16 males and 3 females ranging in age from 1.5 to 61 years (median, 34 years). With two exceptions, one benign cystic ovarian teratoma in which intraoperative cytology was used to diagnose an associated adult-type carcinoma and one undescended testis in which seminoma presented as an abdominal mass, the material reviewed included no examples of primary gonadal GCT. RESULTS: The authors studied 7 primary and 13 metastatic GCTs; these studies were based on 13 in vivo aspirations, 4 intraoperative preparations, and 3 samples of body cavity fluids. All samples were correctly interpreted as malignant, and only one was incorrectly classified as a non-GCT malignancy. CONCLUSIONS: Clinical and cytologic findings are useful in the diagnosis of GCTs and their metastases. Incorrect interpretation of these neoplasms as poorly differentiated malignancies of other types may deprive the patient of effective chemotherapy. Air-dried, Romanowsky-stained smear material and cell block sections may contribute to the resolution of diagnostic dilemmas. 相似文献
20.
The barrier function, surface biochemistry, and morphology of confluent monolayers of endothelial cells isolated from different segments of the bovine lung vasculature [microvessels (BLMVEC), vein (BPVEC) and artery (BPAEC)] were grown in culture and compared. A number of common cell surface proteins were identified along with two proteins of 46 and 48 kDa found exclusively on BPVEC. Lectin affinity chromatography revealed multiple glycosylation differences. The lectins, Arachis hypogaea (AHA) and Lycopersicum esculentum (LEA) agglutinins, interacted with several glycoproteins of BLMVEC but not of BPAEC. Bandeiraea simplicifolia (BS-1) and Caragana arborescens (CAA) agglutinins recognized several glycoproteins of BPVEC and BPAEC but not BLMVEC. Permeabilities were much lower for BLMVEC than BPAEC or BPVEC monolayers, with a range of about 16-fold less for sucrose to 2-fold less for albumin. Electron microscopy revealed that BLMVEC have a greater surface density of plasmalemmal vesicles (approximately 4-fold) and more extensively developed intercellular junctions with more focal membrane adhesion sites per junction (approximately 9-fold) than the other cells. We conclude that: i) BLMVEC monolayers form a much more restrictive barrier to molecular transport as a result of the tighter junctional formation; and ii) endothelial surface glycoproteins may be differentially glycosylated depending on their segmental location within the vasculature. 相似文献