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   813篇
  免费   74篇
  国内免费   1篇
电工技术   6篇
综合类   2篇
化学工业   273篇
金属工艺   16篇
机械仪表   2篇
建筑科学   51篇
矿业工程   4篇
能源动力   9篇
轻工业   151篇
水利工程   14篇
无线电   48篇
一般工业技术   101篇
冶金工业   144篇
原子能技术   3篇
自动化技术   64篇
  2024年   5篇
  2023年   11篇
  2022年   36篇
  2021年   62篇
  2020年   28篇
  2019年   29篇
  2018年   28篇
  2017年   19篇
  2016年   24篇
  2015年   34篇
  2014年   26篇
  2013年   55篇
  2012年   42篇
  2011年   44篇
  2010年   36篇
  2009年   40篇
  2008年   40篇
  2007年   33篇
  2006年   24篇
  2005年   35篇
  2004年   19篇
  2003年   18篇
  2002年   18篇
  2001年   7篇
  2000年   11篇
  1999年   14篇
  1998年   22篇
  1997年   12篇
  1996年   12篇
  1995年   9篇
  1994年   7篇
  1993年   13篇
  1992年   7篇
  1991年   6篇
  1990年   5篇
  1989年   7篇
  1988年   4篇
  1986年   3篇
  1985年   3篇
  1983年   5篇
  1981年   2篇
  1978年   5篇
  1977年   4篇
  1976年   2篇
  1975年   2篇
  1974年   2篇
  1973年   3篇
  1972年   2篇
  1964年   2篇
  1902年   2篇
排序方式: 共有888条查询结果,搜索用时 15 毫秒
101.
The authors investigated the experiences related to becoming psychotherapists for 5 counseling psychology doctoral trainees in their first prepracticum course. Qualitative analyses of weekly journals indicated that trainees discussed challenges related to becoming psychotherapists (e.g., being self-critical, having troubling reactions to clients, learning to use helping skills), gains made during the semester related to becoming psychotherapists (e.g., using helping skills more effectively, becoming less self-critical, being able to connect with clients), as well as experiences in supervision and activities that helped them cope with their anxieties. Results are discussed in 5 broad areas: feelings about self in role of psychotherapist, awareness of reactions to clients, learning and using helping skills, reactions to supervision, and experiences that fostered growth. Implications for training and research are provided. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
102.
The effect of chitin, poly-beta-(1 --> 4)-N-acetyl-glucosamine, and chitosan, a polymer of glucosamine obtained by the deacetylation of chitin, on growth and nutrient digestibility was studied in grass shrimp, Penaeus monodon. Shrimp were fed for 8 wk diets containing no supplement (control) or 2, 5 or 10 g/100 g chitin or chitosan. Each diet was fed to triplicate groups of shrimp with a mean initial body weight of 0.45 +/- 0.05 g. Significantly higher body weight gains were observed in shrimp fed the 5% chitin diet than in those fed the 10% chitin or the control diet. The weight gain of shrimp decreased as dietary chitosan supplementation level increased (r = 0. 87, P < 0.05). Feed efficiencies (FE) and protein efficiency ratios (PER) followed the same pattern. Lower protein and lipid digestibilities and lower body protein and lipid contents were observed in shrimp fed all chitosan-containing diets than in controls (P < 0.05). Carbohydrate digestibility was lower in shrimp fed the 10% chitosan diet than in those fed the control diet. Lower protein and lipid digestibilities, body lipid content and blood cholesterol concentration were observed in shrimp fed the 10% chitin diet compared with controls (P < 0.05). Higher weight gains, body lipid contents and blood cholesterol concentrations were observed in shrimp fed the 2 and 5% chitin diets than in those fed the chitosan diets. Shrimp fed the 5% chitin diet had higher protein and lipid digestibilities and higher body protein content than those fed the 5% chitosan diet (P < 0.05). These data suggest that dietary chitin, supplemented at 5%, enhances P. monodon growth, whereas chitosan depresses shrimp growth, regardless of the supplementation level.  相似文献   
103.
In this brief commentary regarding Rogers' (1957) paper (see record 2007-14639-002), I comment on Rogers' statement about personality change, the six conditions, and the resulting hypotheses. I conclude that the construct of therapeutic personality change needs to be reformulated to include interpersonal changes, and that the six conditions can facilitate therapeutic personality change, but are neither necessary nor sufficient for therapeutic personality change. I also suggest that several components from current common factors models (e.g., building expectations of change, encouraging corrective experiences) and a consideration of boundaries need to be included into a reformulation of Rogers' propositions. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
104.
PURPOSE: Preoperative radiation with combined chemotherapy is effective in shrinking advanced rectal cancer locally and facilitating subsequent surgery. Suppository delivery of 5-fluorouracil is associated with less toxicity and higher rectal tissue concentrations than intravenous administration. This prompted us to evaluate suppository and intravenous administration of 5-fluorouracil and mitomycin C with concomitant radiation to determine associated toxicity. METHODS: Rectal, liver, lymph node, and lung tissue and systemic and portal blood were collected serially from male Sprague Dawley rats to determine drug concentrations following suppository or intravenous delivery of 5-fluorouracil or mitomycin C. Thirty-six animals were randomly assigned to treatment groups and received 5-fluorouracil suppositories, mitomycin C suppositories, or an equivalent intravenous dose of 5-fluorouracil or mitomycin C 30 minutes before radiation therapy. Before and 3, 6, 10, and 15 days following this treatment, blood was collected, colonoscopy was performed, and rectal tissue was harvested for histologic examination. RESULTS: Mitomycin C suppository was significantly less toxic compared with intravenous delivery, and higher rectal tissue concentrations were observed from 10 to 30 minutes (P < 0.05). Compared with intravenous 5-fluorouracil administration and radiation, 5-fluorouracil suppository and radiation resulted in additive myelosuppression at day 6 (P < 0.05) with rapid recovery. CONCLUSIONS: 5-Fluorouracil and mitomycin C suppository delivery combined with radiation causes less systemic toxicity and is more effective than intravenous administration.  相似文献   
105.
Thirteen adult psychotherapy clients currently in long-term therapy were interviewed twice, with semistructured protocols, about their experiences with helpful instances of therapist self-disclosure. Data were analyzed with a qualitative methodology. Results indicated that helpful therapist self-disclosures (a) occurred when these clients were discussing important personal issues, (b) were perceived as being intended by therapists to normalize or reassure the clients, and (c) consisted of a disclosure of personal nonimmediate information about the therapists. The therapist self-disclosures resulted in positive consequences for these clients that included insight or a new perspective from which to make changes, an improved or more equalized therapeutic relationship, normalization, and reassurance. Implications for psychotherapy are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
106.
The effect of bradykinin on the mobilization of arachidonic acid was analyzed separately by acylation and degradation. Acylating activity was determined by the incorporation of [14C]arachidonic acid into the phospholipids at different times. Different concentrations of bradykinin had no effect on the phospholipid acylating activities. The degradation of the phospholipids was performed on renal medullary slices prelabeled with [14C]arachidonic acid. Treatment with bradykinin produced an initial degradation of phosphatidylcholine, phosphatidylethanolamine and phosphatidylinositol, with a concomitant increase in lysophosphatidylcholine, lysophosphatidylethanolamine and lysophosphatidylinositol within 5 min of incubation. Phosphatidylcholine-, phosphatidylethanolamine-and phosphatidylinositol-labeling increased thereafter and reached the control values after 10 min of incubation. After 30 min, incubation of prelabeled slices with bradykinin produced a significant concentration-dependent increase in the phospholipid-labeling by reutilization of [14C]arachidonic acid. The effect of bradykinin on the phospholipid-labeling was blocked by preincubation with increasing concentrations of dBc AMP. Mepacrine also blocked the bradykinin stimulation in phosphatidylcholine and phosphatidylethanolamine, but had no effect on bradykinin-induced changes in the phosphatidylinositol arachidonic acid moiety.  相似文献   
107.
In a rural arid area without suitable receiving water the treated wastewater of a low loaded municipal wastewater treatment plant with full nutrient removal and additional post treatment steps is infiltrated into the unsaturated soil for groundwater recharge. Groundwater probes at increasing distances from the infiltration point have been sampled every two months over a period of 14 months. Beside conventional parameters (nutrients, carbon, and bacterial counts) samples were analysed for pharmaceutically active substances. Depending on and corresponding to their chemical structure and their fate during wastewater treatment, the selected substances showed different behaviour in the saturated zone of the groundwater. The antiepileptic Carbamazepine behaves very conservative and only is removed negligible even after long flow times within the subsurface zone. For other substances like the tranquilizer Diazepam or the analgesics Diclofenac a partial elimination during the different steps of wastewater treatment can be observed. Further degradation could be observed during the subsequent subsurface passage. In correlation with flow time additional removal of these substances from the aqueous phase can be observed. The musk substances Galaxolide and Tonalide were removed to some extend but not as good as the previous mentioned compounds.  相似文献   
108.
Micropollutants as pharmaceutical active compounds (PhACs), residuals of personal care products or endocrine disrupting chemicals are of increasing interest in water pollution control. In this context the removal efficiencies of sewage treatment plants (STPs) are of importance, as their effluents are important point sources for the release of those substances into the aquatic environment. Activated sludge based wastewater treatment is the worldwide prevalently used treatment technique. In conventional plants the separation of treated wastewater and sludge occurs via sedimentation. A new development is the application of membrane technology for this separation step. The studies focus on the influence of the solids retention time (SRT) on the removal efficiency, as the SRT is the most important parameter in the design of STPs. A conventional activated sludge plant (CASP) and a membrane bioreactor (MBR) were operated at different SRTs. The substances selected are the antiepileptic carbamazepine, the analgesics diclofenac and ibuprofen, the lipid regulator bezafibrate, the polycyclic musks tonalide and galaxolide and the contraceptive 17alpha-ethinylestradiole. No significant differences in the removal efficiency were detected. Due to the absence of suspended solids in the MBR effluent, substances with high adsorption potential could be retained to slightly higher amounts.  相似文献   
109.
To study the involvement of lipoxygenase (LOX) and oxidising agent potassium iodate (KIO3) in rheological behaviour of dough, mixograph and alveograph tests were performed using durum cultivars differing for quality and endogenous levels of LOX. Both tests were done in standard condition and with the adding of KIO3 and of LOX and/or its substrate, utilised singly or in different combinations. The effects of these treatments were related to change of ‐SH and S–S content in relative mixograph dough. The mixograph and alveograph responses showed that the KIO3 had an improving effect on dough tenacity and that the adding of LOX system enhanced this trend; on the contrary, the LOX system alone seemed not affect mixing stability. No relation was found between rheological responses and ‐SH and S–S content in the mixograph doughs. The results obtained could suggest that in durum wheat the main effect of LOX could be ascribable to bleaching action because of the co‐oxidation of carotenoid pigments.  相似文献   
110.
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