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   1079篇
  免费   34篇
  国内免费   3篇
电工技术   32篇
化学工业   254篇
金属工艺   27篇
机械仪表   28篇
建筑科学   26篇
矿业工程   2篇
能源动力   30篇
轻工业   104篇
水利工程   7篇
石油天然气   3篇
无线电   41篇
一般工业技术   187篇
冶金工业   241篇
原子能技术   25篇
自动化技术   109篇
  2023年   7篇
  2022年   29篇
  2021年   21篇
  2020年   12篇
  2019年   24篇
  2018年   20篇
  2017年   17篇
  2016年   25篇
  2015年   13篇
  2014年   38篇
  2013年   47篇
  2012年   56篇
  2011年   67篇
  2010年   40篇
  2009年   46篇
  2008年   51篇
  2007年   51篇
  2006年   40篇
  2005年   37篇
  2004年   32篇
  2003年   21篇
  2002年   31篇
  2001年   19篇
  2000年   13篇
  1999年   26篇
  1998年   88篇
  1997年   48篇
  1996年   34篇
  1995年   23篇
  1994年   25篇
  1993年   18篇
  1992年   8篇
  1991年   7篇
  1990年   3篇
  1989年   14篇
  1988年   11篇
  1987年   7篇
  1986年   3篇
  1985年   4篇
  1984年   4篇
  1983年   3篇
  1981年   2篇
  1980年   3篇
  1979年   3篇
  1977年   4篇
  1976年   5篇
  1974年   2篇
  1973年   4篇
  1971年   2篇
  1969年   3篇
排序方式: 共有1116条查询结果,搜索用时 15 毫秒
91.
A hybrid AWD/AND drive technique has been developed in which an Address‐While‐Display (AWD) scheme is combined with an AND logic characteristic that gas discharges demonstrate. The AWD technique enables AC‐PDPs to be driven at high luminance, while the AND logic reduces the number of scan drivers by an order of magnitude. A detailed analysis of the addressing operation has been made. The hybrid drive utilizes the AND logic in two ways: (1) a combination of two voltage pulses and (2) a combination of a voltage pulse and discharge‐priming particles. It was found that the addressing operation requires the establishment of a discharge between the scan and data electrodes, and also between the scan and display electrodes.  相似文献   
92.
93.
In this study, a new marine oil that contains 45% docosahexaenoic acid (DHA, 22∶6n−3) and 13% docosapentaenoic acid (DPA, 22∶5n−6) was administered to rats. The metabolism and distribution of DPA in rats was investigated. In experiment 1, the effects of DHA and n−6 fatty acids (linoleic acid, I A; arachidonic acid, AA; and DPA) on AA contents were investigated in vivo. LA group: LA 25%, DHA 30%; LA-DPA group: LA 15%, DPA 10%, DHA 35%; LA-AA-DPA group: LA 10%, AA 5%, DPA 10%, DHA 35% were administered to rats for 4 wk. In the liver, the AA content in the LA-DPA and LA-AA-DPA groups was significantly higher than in the LA group. The decreased AA contents in the LA group might be caused by DHA administration. Although DHA also was administered in the LA-DPA and LA-AA-DPA groups, the AA contents in these two groups did not decrease. These results suggested that DPA retroconverted to AA, blunting the decrease in AA content caused by DHA administration. To conduct a detailed investigation on DPA metabolism and its relation with AA and DHA, rat hepatocytes were cultured with pruified DPA and DHA for 24 h. We discovered the retroconversion of DPA to AA occurred only when AA content was decreased by a high DHA administration; it did not occur when AA content was maintained at a normal level.  相似文献   
94.
An anticarbamazepine antibody was detected in the serum of a patient with severe carbamazepine-induced serum sickness. We found that the patient's T cells and IgG antibody recognized an epitope which appeared in subjects showing an allergic reaction, as well as that in subjects who showed no allergic reaction, after long-term carbamazepine therapy. These results show that an anti-carbamazepine immune response does not occur in the majority of subjects who undergo long-term carbamazepine therapy without developing allergic symptoms, although the immunodominant haptenic epitope of carbamazepine is present in their sera.  相似文献   
95.
The bacteria isolated from the patients with lower respiratory tract infections were collected by institutions located throughout Japan, since 1981. Ikemoto et al. have been investigating susceptibilities of these isolates to various antibacterial agents and antibiotics, and characteristics of the patients and isolates from them each year. Results obtained from these investigations are discussed. In 16 institutions around the entire Japan, 557 strains of presumably etiological bacteria were isolated mainly from the sputa of 449 patients with lower respiratory tract infections during the period from October 1996 to September 1997. MICs of various antibacterial agents and antibiotics were determined against 98 strains of Staphylococcus aureus, 93 strains of Streptococcus pneumoniae, 84 strains of Haemophilus influenzae, 84 strains of Pseudomonas aeruginosa (non-mucoid strains), 17 strains of Pseudomonas aeruginosa (mucoid strains), 31 strains of Moraxella subgenus Branhamella catarrhalis, 21 strains of Klebsiella pneumoniae etc., and the drug susceptibilities of these strains were assessed except for those strains that died during transportation. 1) S. aureus S. aureus strains for which MICs of oxacillin (MPIPC) were higher than 4 micrograms/ml (methicillin-resistant S. aureus) accounted for 67.3%. The frequency of the drug resistant bacteria increased comparing to the previous year's 52.7%. Arbekacin (ABK) and vancomycin (VCM) showed the highest activities against both S. aureus and MRSA with MIC80s of 1 microgram/ml. 2) S. pneumoniae Imipenem (IPM) and panipenem (PAPM) of carbapenems showed the most potent activities with MIC80s of 0.063 microgram/ml. Faropenem (FRPM) showed the next potent activity with MIC80 of 0.125 microgram/ml. The other drugs except erythromycin (EM), clindamycin (CLDM) and tetracycline (TC) were active against S. pneumoniae tested with MIC80s of 8 micrograms/ml or below. 3) H. influenzae The activities of all drugs were potent against H. influenzae tested with MIC80s of 4 micrograms/ml or below. Cefotiam (CTM), cefmenoxime (CMX), cefditoren (CDTR) and ofloxacin (OFLX) showed the most potent activities with MIC80s of 0.063 microgram/ml. 4) P. aeruginosa (mucoid strains) Tobramycin (TOB) showed the most potent activity against P. aeruginosa (mucoid strains) with MIC80 of 1 microgram/ml. Ceftazidime (CAZ), cefsulodin (CFS), IPM, gentamicin (GM), ABK and ciprofloxacin (CPFX) showed the next potent activities, with MIC80s of 2 micrograms/ml. The MIC80s of the other drugs ranged from 4 micrograms/ml to 16 micrograms/ml. 5) P. aeruginosa (non-mucoid strains) TOB and CPFX showed the most potent activities against P. aeruginosa (non-mucoid strains) with MIC80s of 1 microgram/ml. The MIC80s of piperacillin (PIPC) and cefoperazone (CPZ) were 16 micrograms/ml in 1995, and they were 64 micrograms/ml in 1996. 6) K. pneumoniae All drugs except ampicillin (ABPC) were active against K. pneumoniae. CMX, cefpirome (CPR), cefozopran (CZOP) and carumonam (CRMN) showed the most potent activities against K. pneumoniae with MIC80s of 0.125 microgram/ml. The MIC80s of the other drugs ranged from 0.25 microgram/ml to 2 micrograms/ml. 7) M.(B) catarrhalis Against M.(B.) catarrhalis, all drugs showed good activities with MICs of 4 micrograms/ml or below. IPM and minocycline (MINO) showed the most potent activities with MICs of 0.063 microgram/ml. Also, we investigated year to year changes in the characteristics of patients, their respiratory infectious diseases, and the etiology. Patients' backgrounds were examined for 557 isolates from 449 cases. The examination of age distribution indicated that the proportion of patients with ages over 60 years was 71.0% of all the patients showing a slight increase over that in 1994. Proportions of diagnosed diseases were as follows: Bacterial pneumonia and chronic bronchitis were the most frequent with 35.9% and 30.3% respectively. They were followed by bronchiectasis with a proportion of 10.  相似文献   
96.
A 42-year-old man, who had worked as a welder for 20 years, was admitted to our hospital complaining of a dry cough. A chest radiograph showed diffuse small nodular shadows and chest computed tomography revealed small patchy opacities. A transbronchial lung biopsy specimen showed welding fume particles mainly located in alveolar space with mild fibrosis of alveolar septa. In order to prevent further fibrosis, bronchopulmonary lavage (BPL) was performed to eliminate the fume particles. The amount of iron particles derived from the total lavage fluid was 911.7 mg.  相似文献   
97.
The authors studied the distribution of lipoprotein(a) (Lp(a)) levels with stratification for age and sex, as well as the relation between Lp(a) and atherosclerotic risk factors in a large Japanese population between 1992 and 1993. The subjects were 1,235 males and 1,762 females over 30 years old. Lp(a) was measured by an enzyme-linked immunosorbent assay. Lp(a) levels were higher in females than in males. The increase in Lp(a) with age was statistically significant, and the proportion of subjects with Lp(a) levels > 30 mg/dl also increased with age. In the obese subjects (body mass index (BMI) (kg/m2) > 26), Lp(a) levels were lower than in the non-obese subjects (BMI < or = 26) (p < 0.01 in males; p < 0.05 in females). Male alcohol drinkers had lower Lp(a) levels than nondrinkers (p < 0.05). Age, low density lipoprotein subtracting Lp(a) cholesterol [Lp(a) x 0.3], and fibrinogen level were all positively correlated with Lp(a) in both sexes. Alcohol consumption (g/day) and triglycerides were inversely correlated with Lp(a) in males, while total cholesterol subtracting Lp(a) cholesterol [Lp(a) x 0.3], high density lipoprotein, and factor VII were positively correlated in females. Multiple logistic regression analysis showed that triglycerides in males and BMI and fibrinogen in females were significant independent variables. The authors conclude that Lp(a) level is affected by various factors, such as alcohol drinking, BMI, sex, and age, and is not only correlated with lipid levels but also with hemostatic factors such as fibrinogen and factor VII.  相似文献   
98.
Spermidine acetyltransferase (SAT) from Escherichia coli was purified about 40,000-fold. The molecular mass of native SAT was 95 kDa, and it consisted of four identical subunits. The products formed from the reaction of acetyl-CoA with spermidine by SAT were N1- and N8-acetylspermidine. The Km values for acetyl-CoA, spermidine, and spermine were 2 microM, 1.29 mM, and 220 microM, respectively. The enzymatic activity increased by 2.5-3.5-fold under the condition of poor nutrition but not in response to cold shock or high pH. By using synthetic oliogonucleotides deduced from amino acid sequences of the peptides in SAT, a polymerase chain reaction product with a length of 250 nucleotides was obtained. Using this polymerase chain reaction product, the gene encoding SAT (speG) was cloned and mapped at 35.6 min in the E. coli chromosome. E. coli cells transformed with the cloned speG gene increased SAT activity by 8-40-fold. The gene encoded a 186-amino acid protein, but SAT consisted of 185 amino acids because the initiator methionine was liberated from the protein. Thus, the predicted molecular mass was 21,756 Da. Significant similarity to aminoglycoside acetyltransferase and peptide N-acetyltransferase was observed in the amino acid sequence 87-141, and some similarity with spermidine-preferential binding protein (potD protein) in the spermidine-preferential uptake system was observed in the amino acid sequence 122-141. The results suggest that the active center of SAT may be located in the COOH-terminal portion.  相似文献   
99.
An electrochemical method has been developed for bonding electrically-conductive adherends. The procedure is based on the electrochemical generation of a curing agent from an otherwise chemically-unreactive precursor mixed with an epoxy resin sandwiched between the bonding members. The one-part epoxy resin is storage stable and cured rapidly on passage of current.  相似文献   
100.
When recombinant Chinese hamster ovary cells were treated with pertussis toxin or genistein, not only lysophosphatidic acid (LPA) but also phosphatidic acid (PA) failed to stimulate progression through the cell cycle in serum-free culture, suggesting that PA and LPA induce cell growth through the same signal transduction pathway. Cell cycle analysis also indicates that cell growth promoted by PA results in enhanced protein production.  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