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991.
992.
本文提出一种MEMS传感器,单片集成温度和气压的检测单元。该传感器采用SOI硅片的上层硅作为压阻薄膜,因此各管芯的薄膜厚度有良好的一致性。传统的背面体硅腐蚀方法未被采用,因为碱性溶液腐蚀体硅会在<111>面自停止,形成57.4°的斜坡,从而增大管芯面积,取而代之的是ICP深硅刻蚀。片上集成两个PN结,结区面积呈比例,可以实现温度检测功能。测试表明在-40-100℃之间都有良好的线性度,PN结的离子注入工艺与压阻注入工艺完全兼容,减少了工艺成本。 相似文献
993.
994.
A novel closed-loop feedback TCP/AQM(Transfer Control Protocol/Active Queue Management) model is proposed in this paper using a discrete-time Markov chain,and a way to calculate the equilibrium distribution of this model is given.In the model,system time is divided into time slots,the bottleneck router queue model and TCP window size model in each slot are analyzed.Finally,by combining adjacent slots,an integrated TCP/AQM analytical model is developed.By this model,the average values of packets dropping rat... 相似文献
995.
Fan Bo Dai Yujie Zhang Xiaoxing Lu Yingjie 《Analog Integrated Circuits and Signal Processing》2009,59(2):207-214
A low power clock recovery circuit for passive HF RFID tag is presented. The proposed clock recovery circuit, based on the
architecture of Phase Locked Loop (PLL), is used to generate a stable system clock when communication occurs from interrogator
to tag with 100% ASK modulation. An envelope detector is designed to detect the incident power from interrogator and control
the operating state of the proposed clock recovery circuit. Loop bandwidth of PLL circuits is minimized to reduce the frequency
deviation when operating in frequency maintaining state. Furthermore, an initialization circuit for loop filter is also used
to speed up locking during initial system power-on-reset. Prototype chips have been fabricated in 0.35 μm 2P4M CMOS technology.
A total current consumption of 3 μA has been achieved in the frequency maintaining state. Measurement results show that, when
communication occurs from interrogator to tag with 100% ASK modulation, clock recovery circuit generates a stable and consecutive
system clock and has an inevitable frequency derivation of 7.5% when operating in frequency maintaining state. 相似文献
996.
Polyol-ester-based thermal pastes containing carbon black, fumed alumina or nanoclay exhibit Bingham plastic behavior with
shear thinning. Carbon black gives double yielding, but fumed alumina and nanoclay give single yielding. The plastic viscosity
increases with the solid content. Antioxidants increase the plastic viscosity and yield stresses. Nanoclay (1.0 vol.%) gives
low shear moduli, high critical shear strain, and high loss tangent, thus resulting in low bond-line thickness and high thermal
contact conductance for smooth (0.009 μm) proximate surfaces. Carbon black (Tokai, 8.0 vol.%) gives high moduli, low critical strain, and low loss tangent, thus
resulting in high bond-line thickness, though the high thermal conductivity due to the high solid content results in high
thermal contact conductance for rough (15 μm) proximate surfaces. Antioxidants enhance the solid-like character, increase the yield stress, plastic viscosity, and bond-line
thickness, and decrease the thermal contact conductance. 相似文献
997.
In the IP multimedia subsystem (IMS) of UMTS, two authentication procedures are necessary for IMS subscribers before accessing
IMS services: (i) packet-switch domain authentication using the authentication and key agreement of the 3rd Generation Partnership
Projects (3GPP AKA), and (ii) IMS authentication using IMS AKA. However, since IMS AKA is based on 3GPP AKA, almost all of
the operations are the same. Besides, IMS AKA needs two round-trips to carry out. Therefore, it is inefficient that almost
all involved steps in IMS AKA are duplicated. Therefore, we propose a one-pass IMS AKA instead of IMS AKA. The one-pass IMS
AKA can keep the security properties of IMS AKA, such as mutual authentication and key agreement. Furthermore, the one-pass
IMS AKA not only has at least 45% improvement over IMS AKA in terms of authentication signaling, but also has 76.5% improvement
over IMS AKA in terms of storage space. 相似文献
998.
Bilgin Metin Kirat Pal Shahram Minaei Oguzhan Cicekoglu 《Analog Integrated Circuits and Signal Processing》2009,60(3):205-213
Operational transconductance amplifiers (OTAs) are widely used in the design of electronically tunable circuits. However,
electronic tunability ranges of the OTA based filters are restricted by the limited bandwidth of the transconductance gain
of the OTA. Furthermore, stability conditions and the linearity of the OTA which depends on the control current restrict the
tunability. In this paper, some trade-offs in the electronically tunable filters are investigated. In addition, the tunability
ranges of some first and second order OTA-C and OTA-RC filters are comparatively examined. Moreover, an OTA-C all-pass filter
circuit is presented. SPICE simulations are performed and stability analyses are given for both of the OTA-C and OTA-RC filters.
Operation of the presented all-pass filter is verified experimentally. 相似文献
999.
Yann Civale Guglielmo Vastola Lis K. Nanver Rani Mary-Joy Jae-Ryoung Kim 《Journal of Electronic Materials》2009,38(10):2052-2062
Mechanisms governing the aluminum-mediated solid-phase epitaxy of Si on patterned crystalline Si substrates have been identified
by studying the deposited material as a function of growth conditions when varying parameters such as temperature, growth
time, and layer-stack properties. Early growth stages can be discerned as first formation of “free” Si at the Al/α-Si interface,
then diffusion of Si along the Al grain boundaries, nucleation at the Si substrate surface, nuclei rearrangement, and finally
crystal growth. The acquired understanding is applied to control the selectivity and completeness of single-crystal growth
in various sizes of contact windows to the Si substrate. 相似文献
1000.
To examine how a lead-free solder joint deforms in a thermal cycling environment, both the elastic and plastic stress and
strain behavior must be understood. Methods to identify evolution of the internal strain (stress) state during thermal cycling
are described. A slice of a package containing a single row of solder joints was thermally cycled from 0°C to 100°C with a
period of about 1 h with concurrent acquisition of transmission Laue patterns using synchrotron radiation. These results indicated
that most joints are single crystals, with some being multicrystals with no more than a few Sn grain orientations. Laue patterns
were analyzed to estimate local strains in different crystal directions at different temperatures during a thermal cycle.
While the strains perpendicular to various crystal planes all vary in a similar way, the magnitude of strain varies. The specimens
were subsequently given several hundred additional thermal cycles and measured again to assess changes in the crystal orientations.
These results show that modest changes in crystal orientations occur during thermal cycling. 相似文献