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   346篇
  免费   31篇
化学工业   89篇
金属工艺   10篇
机械仪表   9篇
建筑科学   19篇
能源动力   11篇
轻工业   55篇
石油天然气   1篇
无线电   32篇
一般工业技术   53篇
冶金工业   38篇
自动化技术   60篇
  2024年   1篇
  2023年   4篇
  2022年   10篇
  2021年   16篇
  2020年   6篇
  2019年   11篇
  2018年   8篇
  2017年   14篇
  2016年   21篇
  2015年   19篇
  2014年   16篇
  2013年   32篇
  2012年   17篇
  2011年   20篇
  2010年   12篇
  2009年   11篇
  2008年   18篇
  2007年   17篇
  2006年   14篇
  2005年   11篇
  2004年   11篇
  2003年   6篇
  2002年   4篇
  2001年   4篇
  2000年   6篇
  1999年   5篇
  1998年   15篇
  1997年   9篇
  1996年   6篇
  1994年   2篇
  1993年   7篇
  1992年   2篇
  1991年   4篇
  1990年   1篇
  1988年   1篇
  1987年   1篇
  1984年   1篇
  1981年   1篇
  1976年   1篇
  1969年   3篇
  1968年   1篇
  1967年   1篇
  1966年   5篇
  1964年   2篇
排序方式: 共有377条查询结果,搜索用时 31 毫秒
1.
The SAFT-γ Mie group-contribution equation of state is used to represent the fluid-phase behavior of aqueous solutions of a variety of linear, branched, and cyclic amines. New group interactions are developed in order to model the mixtures of interest, including the like and unlike interactions between alkyl primary, secondary, and tertiary amine groups (NH2, NH, N), cyclic secondary and tertiary amine groups (cNH, cN), and cyclic methine-amine groups (cCHNH, cCHN) with water (H2O). The group-interaction parameters are estimated from appropriate experimental thermodynamic data for pure amines and selected mixtures. By taking advantage of the group-contribution nature of the method, one can describe the fluid-phase behavior of mixtures of molecules comprising those groups over broad ranges of temperature, pressure, and composition. A number of aqueous solutions of amines are studied including linear, branched aliphatic, and cyclic amines. Liquid–liquid equilibria (LLE) bounded by lower critical solution temperatures (LCSTs) have been reported experimentally and are reproduced here with the SAFT-γ Mie approach. The main feature of the approach is the ability not only to represent accurately the experimental data employed in the parameter estimation, but also to predict the vapor–liquid, liquid–liquid, and vapor–liquid–liquid equilibria, and LCSTs with the same set of parameters. Pure compound and binary phase diagrams of diverse types of amines and their aqueous solutions are assessed in order to demonstrate the main features of the thermodynamic and fluid-phase behavior.  相似文献   
2.
An alternative for reducing emissions from marine fuel is to blend bio-oil from lignocellulose non-edible feedstocks to diesel fossil fuels. Phase diagrams of the ternary systems were built to represent the transition from heterogeneous regions to homogeneous regions. Four homogeneous blends of bio-oil of eucalyptus-bioethanol-marine gasoil were experimentally characterized with respect to the most important fuel parameters for marine engines: water content, flash point, low heating value, viscosity, and acidity. Blends with closer properties to marine gasoil replacement, lower costs, and environmental impacts should be tested for large engines.  相似文献   
3.
4.
BACKGROUND/AIMS: The aim of the study was to assess the impact factor of HCV and HGV in fulminant hepatic failure. METHODS: The 5'-untranslated regions of HCV RNA and HGV RNA and a segment of the core antigen sequence of HBV were amplified after extracting the nucleic acids from snap-frozen tissue aliquots from explanted livers of 26 consecutive patients undergoing orthotopic liver transplantation for fulminant hepatic failure preoperatively diagnosed as either autoimmune (n=2), HAV/HBV (n=8), toxic (n=4) or aetiologically unknown (n=12). RESULTS: HCV RNA was detected in five of 26 (19.2%) livers with fulminant hepatic failure. All five HCV RNA-positive livers belonged to the group of non-toxic, non-autoimmune liver failure (n=20), three of them were found in the group of liver failure with unknown aetiology (n=12) and two in the group of HBV-associated liver failure (n=7), making an HCV incidence of 25%, 25% and 28.6%, in the different groups, respectively. HGV RNA was detected in 10 of 17 (58.8%) explants and in all four groups of fulminant hepatic failure as defined preoperatively. HBV DNA was identified in six livers of 26 patients (23.1%) with fulminant hepatic failure. Neither HCV RNA nor HBV DNA was detected in the livers of patients with toxic or autoimmune fulminant hepatic failure. CONCLUSIONS: These results indicate that HBV and HCV, but not HGV, play an aetiologic role in fulminant hepatic failure. HCV-positive cases were concentrated either in the group of otherwise unexplained fulminant hepatic failure or in the group of HBV fulminant hepatic failure. HGV-positive cases, on the other hand, were found within all four preoperatively defined groups, indicating a role as cofactor rather than as single aetiologic agent.  相似文献   
5.
Incidence of gastrointestinal tuberculosis increases in the western world. Exact epidemiological data about this rare extrapulmonological disease are not available in Hungary. Three advanced cases with intestinal tuberculosis have been reported, all of them recognised during surgery due to complications. The clinicopathological correlations are briefly reviewed, and the importance of early diagnosis is emphasized.  相似文献   
6.
A turntable dynamometer has been constructed for the accurate measurement of power input and mixing applications in bench stirred tank reactors. The main feature of this device is a pneumatic bearing with complementary conical parts. The conical pneumatic bearing permitted to apply eccentric loads without affecting its stability. The static friction torque in the pneumatic bearing was very small, 4 × 10?4 Nm, and can be neglected in the experimental ranges of measured torques, i.e. from 5 × 10?3 to 2.21 Nm. In accordance with the instrumentation used, the deviations obtained with the apparatus are less than 10% at low torque readings. At moderate torques, deviations lower than 1% are routinely obtained. Several power input measurements show that the obtained data scatter is lower than 2.5%. The power input response in the turbulent regime is in agreement with dimensional analysis: the power input depends on the cube of the impeller speed. In addition, data obtained with a turbine impeller under ungassed conditions agree with the predictions of a published correlation, which takes into account several geometrical parameters.  相似文献   
7.
Dermoid cysts of the pancreas, also called cystic teratomas, are a rare entity and are included in the group of neoplasms with a germ cell origin. Only twelve cases have been described in the world literature. The symptomatology is due to tumor compression of the neighboring tissues. Ultrasonography and computed tomography may be helpful, but there are no pathognomonic data for their preoperative recognition. The differential diagnosis should include all other cystic tumors of the pancreas. Complete surgical removal is mandatory. We describe the diagnostic and surgical procedures in a 74 year-old man with a pre-operatively unsuspected dermoid cyst. We review the previously published cases and emphasize the appropriate therapeutical management.  相似文献   
8.
Endometriosis is a common gynecological disorder that has been associated with endometrial, breast and epithelial ovarian cancers in epidemiological studies. Since complex diseases are a result of multiple environmental and genetic factors, we hypothesized that the biological mechanism underlying their comorbidity might be explained, at least in part, by shared genetics. To assess their potential genetic relationship, we performed a two-sample mendelian randomization (2SMR) analysis on results from public genome-wide association studies (GWAS). This analysis confirmed previously reported genetic pleiotropy between endometriosis and endometrial cancer. We present robust evidence supporting a causal genetic association between endometriosis and ovarian cancer, particularly with the clear cell and endometrioid subtypes. Our study also identified genetic variants that could explain those associations, opening the door to further functional experiments. Overall, this work demonstrates the value of genomic analyses to support epidemiological data, and to identify targets of relevance in multiple disorders.  相似文献   
9.
10.
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