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171.
Design of a 3780-point IFFT processor for TDS-OFDM 总被引:2,自引:0,他引:2
Zhi-Xing Yang Yu-Peng Hu Chang-Yong Pan Lin Yang 《Broadcasting, IEEE Transactions on》2002,48(1):57-61
This correspondence presents a design of 3780-point IFFT processor for TDS-OFDM terrestrial DTV transmitter using FPGA. It demonstrates the algorithm design and error analysis of the processor, which can achieve a throughput of 7.56M complex IFFT operations per second. This design meets the signal-to-quantization noise ratio requirement of the TDS-OFDM system. It consists of two FPGA and one dual-port RAM. The data stream pipeline algorithm is implemented 相似文献
172.
Clinical manifestations and peripheral blood lymphocyte subset changes were studied in patients with myasthenia gravis (MG) to elucidate the mechanism of clinical improvement following treatment, with thymectomy (Tx) or glucocorticoid (GC) therapy. The changes found were: 1. There was a significant increase in percentages of CD3+, CD29+ CD4+ cells and CD4/CD8 ratio and a significant decrease in percentages of CD8+ and CD16,56+ cells in patients who had never been treated with any immune therapy. 2. After Tx or GC therapy, CD3+ and CD4+, CD29+ cells were decreased, but the number CD19+ and CD16, CD56 cells did not change. 3. Tx had a special effect on CD8+ cells. In most of the patients who showed clinical improvement after Tx, CD8+ cells were increased and CD4/CD8 ratio wad decreased. 4. Anti-acetylcholine receptor (AChRAb) titers were markedly decreased after GC therapy. These results indicate that there were obvious abnormalities in cell-mediated immunity in addition to those in humoral immunity in myasthenia gravis. These abnormalities tended to be normalized after Tx or GC therapy. 相似文献
173.
OBJECTIVE: To study the etiology and early diagnosis of hypergonadotropic amenorrhea and to explore the appropriate treatment for preserving their reproductive function. METHODS: 126 cases of secondary amenorrhea with serum follicular stimulating hormone (FSH) levels > or = 40 IU/I, were analysed. Their clinical manifestations, karyotypes, ovarian morphology and histology, reproductive hormone assays, and responses to estrogen therapy and ovulation induction were studied. RESULTS: 6 cases presented with histories of ovarian surgery, radiotherapy or chemotherapy. Among the other 120 cases, 18 manifested amenorrhea before or at 25 years of age, 102 developed amenorrhea after age 25. In the former group, 16 (88.9%) showed unilateral or bilateral gonadal dysgenesis, and the other 2(11.1%) were defined as resistant ovaries. Abnormalities of sex chromosome karyotype occurred in 44.4% (8/ 18). In the latter group, 68 underwent laparotomy or laparoscopy examination. Morphological and histological examinations of both ovaries showed atrophic ovaries in all cases accompanied by 30.9% (21/ 68) unilateral gonadal dysgenesis; sex chromosomal abnormality was found in only one with no sexual immaturation. The efficacy of estrogen treatment was significantly better among cases with amenorrhea less than 1 year as compared with those longer than 1 year. Clomiphene challenge test given to 8 cases during their irregular menstrual stages produced an elevation of FSH levels to > 20 IU/I. without any response of estradiol secretion. CONCLUSIONS: The earlier estrogen therapy is initiated, the greater possibility of pregnancy will be achieved in cases suffering from hypergonadotropic amenorrhea. The clomiphene challenge test may provide evidence of waning ovarian function for early diagnosis. 相似文献
174.
Hayden J.D. Taft R.C. Kenkare P. Mazure C. Gunderson C. Nguyen B.-Y. Woo M. Lage C. Roman B.J. Radhakrishna S. Subrahmanyan R. Sitaram A.R. Pelley P. Lin J.-H. Kemp K. Kirsch H. 《Electron Devices, IEEE Transactions on》1994,41(12):2318-2325
An advanced, high-performance, quadruple well, quadruple polysilicon BiCMOS technology has been developed for fast 16 Mb SRAM's. A split word-line bitcell architecture, using four levels of polysilicon and two self-aligned contacts, achieves a cell area of 8.61 μm2 with conventional I-line lithography and 7.32 μm2 with I-line plus phase-shift or with deep UV lithography. The process features PELOX isolation to provide a 1.0 μm active pitch, MOSFET transistors designed for a 0.80 μm gate poly pitch, a double polysilicon bipolar transistor with aggressively scaled parasitics, and a thin-film polysilicon transistor to enhance bitcell stability. A quadruple-well structure improves soft error rate (SER) and allows simultaneous optimization of MOSFET and bipolar performance 相似文献
175.
羰基铁类随机混合吸波材料等效电磁参数的计算 总被引:3,自引:0,他引:3
本文为计及多重散射偶极子间的相互作用,引入参量εh和μh,导得一组公式。它不仅能计算铁氧体类也能计算羰基铁类的随机混合吸波材料的等效电磁参数,均与实验结果吻合良好。 相似文献
176.
The current-voltage characteristics of the P-N double quantum well resonant interband tunneling (RIT) diodes in InAlAs-InGaAs system have been improved in this letter. The peak-to-valley current ratio (PVCR) is as high as 144 at room temperature. As we know, this is the highest room temperature PVCR ever reported in any tunneling devices. Moreover, the influence of the central barrier thickness varying from 10 Å to 30 Å on the device characteristics is also studied 相似文献
177.
Implicit deregistration in a PCS network 总被引:1,自引:0,他引:1
Registration/deregistration is required in a PCS network when a portable moves between registration areas. Several schemes were proposed to deregister a portable after it moves out of a registration area (RA). A simple scheme called implicit deregistration totally eliminates network traffic due to deregistration. However, this scheme may delete valid registration records. Thus, the size of a registration database must be sufficiently large to ensure low probability that a valid registration record is deleted. This paper describes an analytic model to determine the size k of the registration database for an RA in the implicit deregistration scheme. If the expected number of portables in an RA is N, then our study indicates that good performance can be achieved if k≃5N 相似文献
178.
179.
The mold compound protects integrated circuit (IC) devices from the environmental attacks (e.g., moisture, contaminants) for its lifetime. Driven by market pressure, environmental regulations, the electronics industry is migrating to provide environmental friendly ("green") products and systems. Two major changes associated with this migration are elimination of lead and toxic halogens from the products. Thus, the halogen-free mold compound will be a part of the "green" IC package. The migration to lead-free electronics impacts the current nongreen IC packaging technology, cost and reliability of manufacturers. This article presents the technology challenges and development trend that manufacturers and end users are facing right now with the introduction of green mold compounds. 相似文献
180.
Chan K.T. Chin A. McAlister S.P. Chang C.Y. Liu J. Chien S.C. Duh D.S. Lin W.J. 《Electron Device Letters, IEEE》2003,24(1):28-30
Very-low-transmission line noise of <0.25 dB at 18 GHz and low power loss /spl les/0.6 dB at 110 GHz have been measured on transmission lines fabricated on proton-implanted Si. In contrast, a standard Si substrate gave much higher noise of 2.5 dB and worse power loss of 5 dB. The good RF integrity of proton-implanted Si results from the high isolation impedance to ground, as analyzed by an equivalent circuit model. The proton implantation is also done after forming the transmission lines at a reduced implantation energy of /spl sim/4 MeV. This enables easier process integration into current VLSI technology. 相似文献