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951.
In man, GHRH has been shown to potentiate the TSH-releasing activity of TRH. To study the way by which GHRH affects TRH-stimulated TSH release, we examined the effect of GHRH (1-29)NH2 on basal and stimulated TSH secretion in intact male rats and superfused dispersed rat pituitary cells. In the intact rats, GHRH(1-29)NH2 potentiated TRH-stimulated TSH release in the evening, but potentiation was not observed in the morning and in dispersed pituitary cells. Basal TSH levels were not changed by GHRH(1-29)NH2. It is concluded that GHRH(1-29)NH2 potentiates the TSH-releasing activity of TRH in the evening in rats possibly through suprahypophyseal disinhibition.  相似文献   
952.
The use of the primitive cell volume and the zero order Laue zone (ZOLZ) pattern is proposed as a means to identify phases in a complex microstructure. A single convergent beam pattern, containing a higher order Laue zone ring, from a nanosized region is sufficient to calculate the primitive cell volume of the phase, while ZOLZ pattern is used to determine the zone axis of the crystal. A computer program is used to screen out possible phases on the basis of the value of measured cell volume. The indexing of the ZOLZ pattern follows in the program to find the zone axis of the identified phase. Combination of these two methods ensures accuracy and reliability of phase identification from a single CBED pattern. An example of the analysis is given from the rapidly solidified Al-Al3Ti system.  相似文献   
953.
The E1A oncoproteins of adenovirus type 5 are potent inducers of apoptotic cell death. To manifest growth promoting and transforming properties, therefore, E1A requires the co-expression of a suppressor of apoptosis. During normal viral infection, this function is provided by the E1B 19 kDa protein. However, the cellular suppressor Bcl-2 can substitute for 19K during infection, and both proteins can effectively cooperate with E1A to facilitate transformation of primary cells in culture. How E1A induces apoptosis and at what point(s) on this pathway Bcl-2 and E1B 19K act are not presently known. Here, we demonstrate that E1A-induced apoptosis is accompanied by specific endo-proteolytic cleavage of poly(ADP-ribose) polymerase (PARP), an event that is linked to the Ced-3/ICE apoptotic pathway in other systems. PARP cleavage was also observed in p53-null cells infected with 19K- virus expressing 13S E1A. In addition to PARP cleavage, expression of E1A caused processing of the zymogen form of CPP32, a Ced-3/ICE protease that cleaves PARP and is required for apoptosis in mammalian cells. These events were prevented when E1A was co-expressed with E1B 19K or BCL-2, which places these suppressors of apoptosis either at or upstream of processing of pro-CPP32.  相似文献   
954.
A 36-year-old man with pharyngeal-cervical-brachial variant of Guillain-Barré syndrome (PCB) was described. Neurologic examination revealed total ophthalmoplegia, pharyngeal-cervical-brachial weakness and hyporeflexia in the upper limbs, sparing power and tendon reflexes in the lower limbs. Enzyme-linked immunosorbent assay showed that he had high titer of IgG antibody to GT1a (1:32,000), which did not cross-react with GQ1 b or GD1a. Thin-layer chromatography immunostaining confirmed that his serum IgG reacted with GT1a. These findings show that IgG anti-GT1a antibody without cross-reactivity with GQ1b plays a role in the development of PCB.  相似文献   
955.
We have shown that large lysosomes appear in thyroids of aging male cream hamsters. To investigate the role of this lysosomal change in the age-dependent reduction in hormone secretion, thyroids of young (<4 months of age) and old (>22 months of age) male and female hamsters were labeled with 125I at near isotopic equilibrium. Changes in thyroid morphology were analyzed by light- and electron-microscopic morphometry. Changes in thyroglobulin processing were analyzed by subcellular fractionation and identification of 125I-compounds by sucrose gradients and reverse-phase high-pressure liquid chromatography (HPLC). Sexual dimorphism present in thyroids of young animals became more marked upon aging. The parallel increase in thyroid weight and thyroglobulin content was more conspicuous in old females than in old males. Two morphological observations were specific to old females: (1) large follicles with flat epithelium and evenly labeled colloid and (2) deposits of amyloid material (possibly immunoglobulin light chain-related) between follicles. Although lysosomes were enlarged in female and male aged thyroids, they did not accumulate iodine. However, after isopycnic centrifugation of crude lysosomal fractions in Percoll gradients, 125I in old thyroids was not distributed mainly in the dense fraction L1 (lysosomes) as in young thyroids, but partly in particles of lower density (light L2 and buoyant fractions). 125I in the lighter particles was mostly found in intact thyroglobulin and in large iodopeptides. This 125I shift towards less dense particles was more marked in females than in males. These results indicate that age delays thyroglobulin progression towards dense lysosomes and suggest that the slower traffic of thyroglobulin in the endocytic pathway contributes to the reduction in thyroid hormone secretion in the aged cream hamster.  相似文献   
956.
Identified and developed a scale to assess problematic interpersonal situations among urban adolescents. In Study 1, problematic situations were identified by focus groups of 6th graders (N = 43). Their relevance was verified in Study 2 by assessing their reported frequency and difficulty in a sample of 6th graders (N = 457) that included mostly African American youth from low-income families. Scales representing 3 dimensions, peer provocation, perceived injustice, and environmental stressors were verified by confirmatory factor analyses. In Study 3, the internal consistency and structure of these scales were cross-validated in a sample of 7th graders (N = 459). All 3 scales were correlated with self-reported violent behavior, drug use, and anxiety and uniquely accounted for 11% to 19% of the variance. These findings have implications for identifying youth at risk for emotional and behavioral problems and for designing more relevant interventions.  相似文献   
957.
The media, perhaps more than any other slice of culture, influence what we think and talk about, what we take to be important, what we worry about. And this was especially true when news of Dolly hit the airwaves and newstands. Most Americans received training in the ethics of cloning before they knew what cloning was. Media coverage fixed the content and outline of the public moral debate, both revealing and creating the dominant public worries about cloning humans. The primary characterization of cloning as an ethical issue centers around three connected concerns: the loss of human uniqueness and individuality, the pathological motivations of a cloner, and the fear of out-of-control scientists.  相似文献   
958.
959.
The in vitro activity of voriconazole was compared with that of itraconazole. Eighty-six isolates of pathogenic molds belonging to 23 species were tested by an agar dilution method in High Resolution medium. Voriconazole was more active than itraconazole against a number of hyaline molds, including several Fusarium spp. and Scedosporium prolificans. Voriconazole and itraconazole showed comparable good activity against several hyaline molds, including Penicillium marneffei and Scedosporium apiospermum, and a number of dematiaceous molds, including Bipolaris australiensis, Cladophialophora bantiana, several Exophiala spp., and several Fonsecaea spp. Our results suggest that voriconazole could be effective against a wide range of mold infections in humans.  相似文献   
960.
The aim of this study was to elucidate the possible causes of elevated low-density lipoprotein (LDL)-cholesterol levels in transplanted patients treated with the immunosuppressant drug, cyclosporine. HepG2 cells, from a well-differentiated cell-line of hepatoma cells, were cultured and used as a model for in vitro hepatocytic LDL uptake. Different concentrations of cyclosporine, which were within the range of concentrations found in humans treated with cyclosporine, were added to tissue culture medium together with 125I-LDL. The results showed that cyclosporine reduced LDL uptake and degradation in HepG2 cells by about 25%. The cells were also pretreated with cyclosporine for 1 to 24 hours and then incubated with new medium containing labeled LDL for 2 hours at 4 degrees C in an LDL-binding assay. The data showed that cyclosporine reduced the subsequent LDL binding. Cyclosporine has no toxic effects on HepG2 cells, as shown by unchanged growth capacity of the cells. By means of a 50-fold excess of unlabeled LDL, a monoclonal anti-LDL receptor antibody, and dextran sulfate, we also evaluated if this inhibition of LDL binding occurred through the LDL receptor-mediated pathway, through non-LDL receptor-mediated pathways, or through both. The results show that cyclosporine reduces LDL binding and uptake by mainly inhibiting the LDL receptor-mediated pathway. We also studied the effect of the LDL-cyclosporine complex on the binding of labelled LDL. The presence of cyclosporine in the LDL particle does not influence the binding behaviour of LDL to its receptor. We also found that cyclosporine reduces the expression of the LDL receptor messenger RNA (mRNA) by about 40%. Thus, the interpretation of this study is that cyclosporine can cause an increase in LDL-cholesterol in the plasma of transplantation patients by reducing the catabolism of LDL in the liver by inhibiting mainly the LDL receptor-mediated catabolism through an effect on LDL receptor synthesis.  相似文献   
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