首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   6677篇
  免费   582篇
  国内免费   529篇
电工技术   416篇
综合类   682篇
化学工业   1026篇
金属工艺   819篇
机械仪表   390篇
建筑科学   220篇
矿业工程   164篇
能源动力   166篇
轻工业   339篇
水利工程   52篇
石油天然气   163篇
武器工业   44篇
无线电   486篇
一般工业技术   674篇
冶金工业   369篇
原子能技术   57篇
自动化技术   1721篇
  2024年   20篇
  2023年   73篇
  2022年   131篇
  2021年   179篇
  2020年   192篇
  2019年   158篇
  2018年   156篇
  2017年   206篇
  2016年   208篇
  2015年   220篇
  2014年   385篇
  2013年   395篇
  2012年   372篇
  2011年   480篇
  2010年   363篇
  2009年   404篇
  2008年   364篇
  2007年   454篇
  2006年   413篇
  2005年   371篇
  2004年   304篇
  2003年   262篇
  2002年   206篇
  2001年   191篇
  2000年   172篇
  1999年   161篇
  1998年   143篇
  1997年   119篇
  1996年   102篇
  1995年   100篇
  1994年   99篇
  1993年   67篇
  1992年   66篇
  1991年   41篇
  1990年   43篇
  1989年   44篇
  1988年   30篇
  1987年   24篇
  1986年   10篇
  1985年   10篇
  1984年   10篇
  1983年   9篇
  1982年   4篇
  1981年   8篇
  1980年   3篇
  1979年   5篇
  1978年   2篇
  1977年   2篇
  1976年   2篇
  1957年   1篇
排序方式: 共有7788条查询结果,搜索用时 15 毫秒
61.
Experimental investigations and Gibbs energy modelling of KCl–LiCl–UCl3 system employing CALPHAD method are reported. Gibbs energy modelling of the subsystems KCl–UCl3 and LiCl–UCl3 was carried out primarily using phase diagram data from the literature. For the Gibbs energy modelling of the KCl–LiCl subsystem, new phase boundary data corresponding to four terminal compositions (xLiCl=0.03, 0.05, 0.95 and 0.97) obtained through differential thermal analysis data along with thermochemical and phase diagram data from the literature were used. Thermal analysis was also carried out for KCl–LiCl eutectic mixture containing small amounts of UCl3 (xUCl3=9.03×103 and 1.79×102). The liquidus temperatures for these compositions were found to be 637 K and 674 K. Electromotive force data for dilute solutions of UCl3 in the KCl–LiCl eutectic melt, measured in the temperature range 708–833 K in the present work, were found to be in good agreement with the literature data. These data were also used as input for the Gibbs energy modelling of the KCl–LiCl–UCl3 system. In order to improve the quality of the resulting Gibbs energy functions of the quasibinaries and the quasiternary, enthalpies of mixing of the corresponding melts estimated using an empirical correlation based on surrounded-ion model were also used as input. Finally, the generated Gibbs energy functions were used to compute phase equilibria.  相似文献   
62.
根据离子膜制碱工艺的特点,与控制图的应用理论相结合,寻找控制对象并选择控制图的类型。通过选择合适的工艺参数,使用控制图的数据处理技术对实际数据进行处理,绘制出控制图,利用参数波动符合正态分布的特点对控制图的波动情况进行分析,用来诊断电解槽运行的受控情况。  相似文献   
63.
根据以固体质量流速和固体装入量为参数的Zenz相图(即压降与表观气速的关系图)和洪江等人的模型[6],对粗聚氯乙烯和细PVC颗粒的水平气力输送进行了合理的预测  相似文献   
64.
Structural analysis derived from the crystallographic studyof the chimeric B72.3 antibody illustrated some major atomicinteractions between complementarity determining region (CDR)residues. For example, hydrogen bonds are formed between H35/H95,L50/H97, H53/H55 and H96/L96 respectively. These CDR residuesmay play important roles in the B72.3–TAG72 (antibody-antigen)interaction either by direct interaction with the TAG72 antigenor by maintaining a CDR loop conformation through atomic interactionsbetween CDR residues. In order to confirm these assumptions,we altered these CDR residues by site-directed mutagenesis anddetermined binding affinities of these mutant chimeric antibodiesfor the TAG72 antigen in a solid-phase radioimmunoassay. Wefound that H55, H95, H97 and L96 are important CDR residuesfor the B72.3–TAG72 interaction. Single amino acid substitutionsof aspartic acid and serine by alanine at H55 of CDR2 and atH95 of CDR3 respectively and of tyrosine by phenylalanine atH97 and L96 of CDR3, significantly reduced the binding affinityfor the TAG72 antigen by 20-, 8-, 16- and 45-fold respectively.Therefore, this study reveals some of the requirements for maintainingthe integrity of the B72.3 antibody combining sites.  相似文献   
65.
本文用DTA和XRD法研究了Na_2O-Al_2O_3-WO_3三元系中的Al_2(WO_4)_3-Na_2WO_4截面的相平衡关系。在这截面中发现一新化合物AlNa_3(WO_4)_2。以45mol%Na_2WO_4为助熔剂生长了Cr~(3+):Al_2(WO_4)_3晶体。  相似文献   
66.
目的 选择固相金属亲和层析柱的金属离子,以优化分离纯化重组戊型肝炎病毒包涵体的条件。方法 在同一试验条件下用4种金属离子柱分离纯化目的蛋白。结果 包涵体经不同离子柱层析时目的蛋白的收获率、纯度、洗脱条件各异。结论 镍离子柱纯化效果最佳。  相似文献   
67.
A novel mechanism to form binary polymer blends is through phase separation by spinodal decomposition in the unstable region of the phase diagram. The present work investigates the effects of thermally‐induced phase separation by spinodal decomposition on the morphology development of liquid crystalline polymer/polycarbonate blends. Moreover, a thermodynamic binary phase diagram is obtained using a twin‐screw extruder at various processing melt temperatures. Differential scanning calorimetry and scanning electron microscopy were used to study the miscibility of the blends and the resulting morphology. A thermodynamic binary phase diagram exhibiting a lower critical solution temperature was obtained. The droplet size distribution of the blend was also obtained and discussed in light of the Cahn‐Hilliard theory.  相似文献   
68.
抗rHu-IFN-αMcAb亲和常数的测定   总被引:1,自引:0,他引:1  
采用ELISA间接法检测抗原-抗体反应系统中游离抗体量的方法,对本实验室制备的5系抗rHu-IFN-αMcAb进行了亲和力测定,获得比较准确的McAb亲和常数。  相似文献   
69.
Dilute, ‘dense phase 1’, and possibly a third regime-‘dense phase 2’, were observed in a vertical 0.02 m diameter pneumatic conveyor using 210 μm sand particles. The transitions were marked by the alterations in the trend of the measured average solids hold-up while varying the solids mass flowrate at constant air velocity. Hydrodynamic characteristics together with the transition criteria for the various transport modes were established. A novel regime diagram based on average gas velocities and solids mass flowrates was developed to identify the operating conditions for these regimes, as well as the limiting solids carrying capacities of the present conveyor. A probable cause of the dilute to dense phase transition is speculated upon.  相似文献   
70.
The viscoelastic behavior, thermodynamic compatibility, and phase equilibria in block copolymer-based pressure-sensitive adhesives were investigated. The block copolymers investigated were: (1) polystyrene-block-polybutadiene-block-polystyrene (SBS) copolymer (KRATON® D-1102, Shell Development Company) and (2) polystyrene-block-polyisoprene-block-polystyrene (SIS) copolymer (KRATON® D-1107, Shell Development Company). The tackifying resins investigated were: (1) WINGTACK® 86 (Goodyear Tire & Rubber Company) and (2) PICCOTAC® 95BHT (Hercules Inc.). Samples of various compositions were prepared by a solution-casting method with toluene as solvent. Measurements of dynamic storage modulus (G'), dynamic loss modulus (G'), and loss tangent (tan δ) were taken, using a Rheometrics Mechanical Spectrometer. It was found that: (1) both WINGTACK 86 and PICCOTAC 95BHT were equally effective in decreasing the plateau modulus (GON), and increasing the glass transition temperature (Tg) of the polyisoprene midblock of KRATON 1107; and (2) WINGTACK 86 was very effective in decreasing the GON and increasing the Tg of the polybutadiene midblock of KRATON 1102, whereas PICCOTAC 95BHT was not. The observed difference between WINGTACK 86 and PICCOTAC 95BHT in decreasing the GON and increasing the Tg of the polybutadiene midblock of KRATON 1102, whereas PICCOTAC 95BHT was not. The observed difference between WINGTACK 86 and PICCOTAC 95BHT in decreasing the GON and increasing the Tg of the polybutadiene midblock of KRATON 1102 (perhaps to SBS block copolymers in general) is explained by the values of the interaction parameter for WINGTACK 86 and KRATON 1102, and for PICCOTAC 95BHT and KRATON 1102. The interaction parameter was determined, using the piezoelectric quartz sorption method. Phase diagrams were constructed for the four block copolymer/tackifying resin systems investigated, using information obtained from both dynamic viscoelastic measurements and optical microscopy. It was found that when mixed with KRATON 1102, PICCOTAC 95BHT formed separate domains whereas WINGTACK 86 did not over the range of concentrations and temperatures investigated. This confirms the evidence obtained from two other independent experimental techniques, namely, dynamic viscoelastic measurements and the piezo-electric sorption method. We have concluded from the present study that PICCOTAC 95BHT is not as an effective tackifying resin as WINGTACK 86, when each is mixed with KRATON 1102. It is pointed out further that information on the order-disorder transition temperature Tr, which was determined from a rheological technique proposed by us, is valuable in determining optimal processing conditions for block copolymer-based pressure-sensitive adhesives.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号