全文获取类型
收费全文 | 3276篇 |
免费 | 120篇 |
国内免费 | 17篇 |
专业分类
电工技术 | 32篇 |
综合类 | 4篇 |
化学工业 | 746篇 |
金属工艺 | 102篇 |
机械仪表 | 71篇 |
建筑科学 | 85篇 |
矿业工程 | 6篇 |
能源动力 | 102篇 |
轻工业 | 131篇 |
水利工程 | 17篇 |
石油天然气 | 10篇 |
无线电 | 298篇 |
一般工业技术 | 695篇 |
冶金工业 | 661篇 |
原子能技术 | 26篇 |
自动化技术 | 427篇 |
出版年
2023年 | 17篇 |
2022年 | 28篇 |
2021年 | 62篇 |
2020年 | 53篇 |
2019年 | 47篇 |
2018年 | 72篇 |
2017年 | 55篇 |
2016年 | 74篇 |
2015年 | 53篇 |
2014年 | 72篇 |
2013年 | 187篇 |
2012年 | 112篇 |
2011年 | 153篇 |
2010年 | 139篇 |
2009年 | 160篇 |
2008年 | 127篇 |
2007年 | 124篇 |
2006年 | 106篇 |
2005年 | 91篇 |
2004年 | 107篇 |
2003年 | 86篇 |
2002年 | 84篇 |
2001年 | 77篇 |
2000年 | 66篇 |
1999年 | 75篇 |
1998年 | 119篇 |
1997年 | 76篇 |
1996年 | 69篇 |
1995年 | 53篇 |
1994年 | 59篇 |
1993年 | 67篇 |
1992年 | 60篇 |
1991年 | 50篇 |
1990年 | 46篇 |
1989年 | 55篇 |
1988年 | 44篇 |
1987年 | 31篇 |
1986年 | 37篇 |
1985年 | 40篇 |
1984年 | 40篇 |
1983年 | 38篇 |
1982年 | 23篇 |
1981年 | 26篇 |
1980年 | 30篇 |
1979年 | 15篇 |
1978年 | 21篇 |
1977年 | 27篇 |
1976年 | 32篇 |
1974年 | 19篇 |
1973年 | 24篇 |
排序方式: 共有3413条查询结果,搜索用时 375 毫秒
161.
Anant K. Singh Wentong Lu Dulal Senapati Sadia Afrin Khan Zhen Fan Tapas Senapati Teresa Demeritte Lule Beqa Paresh Chandra Ray 《Small (Weinheim an der Bergstrasse, Germany)》2011,7(17):2517-2525
A recent gold nanotechnology‐driven approach opens up a new possibility for the destruction of cancer cells through photothermal therapy. Ultimately, photothermal therapy may enter into clinical therapy and, as a result, there is an urgent need for techniques to monitor the tumor response to therapy. Driven by this need, a nanoparticle surface‐energy‐transfer (NSET) approach to monitor the photothermal therapy process by measuring a simple fluorescence intensity change is reported. The fluorescence intensity change is due to the light‐controlled photothermal release of single‐stranded DNA/RNA via dehybridization during the therapy process. Time‐dependent results show that just by measuring the fluorescence intensity change, the photothermal therapy response during the therapy process can be monitored. The possible mechanism and operating principle of the NSET assay are discussed. Ultimately, this NSET assay could have enormous potential applications in rapid, on‐site monitoring of the photothermal therapy process, which is critical to providing effective treatment of cancer and multidrug‐resistant bacterial infections. 相似文献
162.
Anshuman Sharma Chuan Zhang Y. Austin Chang Ray Knoeppel Dane Morgan 《Corrosion Science》2011,(5):1724-1731
This work summarizes the experimental literature to date on Al-alloy sacrificial anodes and shows that the presence of Sn as an alloying element in solid solution form consistently debases the alloy corrosion potential. This study then assesses the lattice expander theory, which states that lattice-expanding dopants can be used to increase Sn solubility in Al and thereby reduce passivation. The thermodynamic effects on Sn solubility of lattice expanders (Ga, Mg, Zr, In and Bi) are predicted with ab-initio methods. Our results support lattice expander theory although we demonstrate that Sn solubility can decrease by alloying with even large dopants if they form compounds with Sn. 相似文献
163.
Simultaneous sequestration of nitrate and phosphate from wastewater using a tailor‐made bacterial consortium in biofilm bioreactor
下载免费PDF全文
![点击此处可从《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Pallavi Mukherjee Chaitali Chanda Moumita Bhaumik Madhurima Ghosh Jaweria Sharmin Poulami Datta Srimoyee Banerjee Parthasarathi Barat Ashoke Ranjan Thakur Lalit Mohan Gantayet Indranil Mukherjee Shaon Ray Chaudhuri 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2018,93(5):1279-1289
164.
SnO2 nanowires and nanobelts have been grown by the thermal evaporation of Sn powders. The growth of nanowires and nanobelts has
been investigated at different temperatures (750–1000°C). The field emission scanning electron microscopic and transmission
electron microscopic studies revealed the growth of nanowires and nano-belts at different growth temperatures. The growth
mechanisms of the formation of the nanostructures have also been discussed. X-ray diffraction patterns showed that the nanowires
and nanobelts are highly crystalline with tetragonal rutile phase. UV-visible absorption spectrum showed the bulk bandgap
value (∼ 3–6 eV) of SnO2. Photoluminescence spectra demonstrated a Stokes-shifted emission in the wavelength range 558–588 nm. The Raman and Fourier
transform infrared spectra revealed the formation of stoichiometric SnO2 at different growth temperatures. 相似文献
165.
Ray William F. Lawrenson Peter J. Davis Rex M. Stephenson J. Michael Fulton Norman N. Blake Roy J. 《Industry Applications, IEEE Transactions on》1986,(4):722-730
Switched reluctance (SR) drives offer the advantages of simple and robust motor construction, high speeds, high overall efficiencies over a wide operating range of torque and speed, simple power converter circuits with a reduced number of switches, and excellent controllability. The basis of these claims is explained. The history of the SR system, in particular the extensive research at Nottingham and Leeds Universities, and the basic operating principles and design considerations for motors and power converters are reviewed. Alternative configurations are discussed. The difficulties of establishing a simple mathematical model for the motor and of calculating torque and inverter VA requirements are examined. A comparison of the VA requirements for SR and pulsewidth modulation (PWM) is given for a 7.85-kW system. Measured drive performance is discussed in terms of efficiency over an operating envelope, specific output, controllability, and power converter ratings. Earlier traction drives, incorporating a constant power range and including regeneration, are reported together with the constant torque industrial drives and more recent traction extensions. The long-term potential of the drive is discussed for a wide range of applications. A comprehensive list of references is provided. 相似文献
166.
The field dependence of real () and imaginary () component of ac susceptibility of superconductors within the critical state model can conveniently be used for evaluating the critical current when field amplitude is larger than the penetration field. A method to analyze the real () and imaginary () component of fundamental ac susceptibility with the objective of extracting the temperature dependence of critical current density J
c(T) is reported. The procedure makes use of the ac susceptibility data of two polycrystalline (Bi-Pb)-2223 samples measured with different excitation amplitudes below and close to the critical temperature. The temperature dependence of J
c is extracted using the isothermal scan over and data. Results obtained from this procedure are found to be in fair agreement with J
c(T) calculated from traditional loss-maximum data. 相似文献
167.
168.
We have investigated laser action in a binary mixture of dyes, Rh-6G and DCM, resulting in tunable laser emission over an extended frequency region. The two dyes absorb the same pump radiation but fluoresce over frequency ranges that are shifted with respect to each other, thereby resulting in extended tunability. Following a time-dependent analysis of a rate-equation model that describe the operation of such a laser, theoretical estimates for optimum dye concentrations and the corresponding extension of the laser tuning range have been obtained. 相似文献
169.
The extensive metabolism and administration of low doses of ethinylestradiol (EE) in preclinical animal species necessitates a sensitive analytical method to quantify the drug at low picogram-per-milliliter concentrations in biological matrixes. A highly sensitive and accurate method based on the derivatization of EE with dansyl chloride coupled with liquid chromatography/tandem mass spectrometry is described. The dansyl derivatization of EE introduced a basic secondary nitrogen into the molecule that was readily ionized in commonly used acidic HPLC mobile phases. The derivative showed an intense protonated molecular ion at m/z 530 under positive turbo ion spray ionization. The collision-induced dissociation of this ion formed a distinctive product at m/z 171, corresponding to the protonated 5-(dimethylamino)naphthalene moiety. The selected reaction monitoring, based on the m/z 530 --> 171 transition, was highly specific for EE, since no background signal was observed from blank plasma obtained from rhesus monkeys. The limit of detection, at a signal-to-noise ratio of 5, was 0.2 fg/mL EE spiked into blank plasma. This allowed for a lower limit of quantitation of 5 pg/mL using a 50-microL plasma sample and 10-microL injection of dansylated derivative into the CTC-PAL Leap autosampler coupled to a Sciex API 4000 mass spectrometer. Using fast-gradient liquid chromatography, the analyte peak eluted at 1.6 min. The validation results showed high accuracy (% bias < 4) and precision (% CV < 7.5) at broad linear dynamic ranges (0.005-20 ng/mL), using deuterated EE as internal standard. Therefore, the facile dansyl derivatization coupled with tandem mass spectral analysis allowed the development of a highly sensitive and specific method for quantitation of trace levels of EE in the plasma of rhesus monkeys dosed orally and intravenously with EE. 相似文献
170.
There is an expanding interest in small-scale methods to evaluate catalysts and chemical reactions at a variety of conditions, ranging up to 6.9 MPa (1000 psig) and 300 degrees C. Multiwell parallel batch techniques are most commonly applied in high-throughput screening systems. In contrast, we describe here a rapid, serial, highly controllable method based on LC-type steel tubing rated for high pressures. The tube, containing a variety of flowing ingredients, such as carrier solvents, catalyst formulations, and reactants, is self-heated ohmically using electrical current from a power supply monitored and regulated with a precision of 0.01%. An array of voltage taps arranged along its length serves to sense the real-time temperature profile of the tube. Reactions are seen as temperature pulses progressing through the reactor, in zones of 200 microL each, and tracked with a temperature precision of 0.1 degrees C. A unique pressure controller was devised to maintain constant reactor pressures despite effluent viscosity fluctuations due to polymerization. Several chemical reaction systems have been characterized to date, including decomposition reactions of di-tert-butyl peroxide, polymerizations of styrene, formation of polyethylene from ethylene, and copolymerization of ethylene with 1-octene. For ethylene polymerization, the amount of mass of polymer formed is proportional to the responses observed. 相似文献