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   377篇
  免费   1篇
  378篇
  2020年   3篇
  2017年   6篇
  2016年   9篇
  2015年   3篇
  2014年   6篇
  2013年   6篇
  2012年   7篇
  2011年   6篇
  2010年   8篇
  2009年   6篇
  2008年   11篇
  2007年   20篇
  2006年   15篇
  2005年   17篇
  2004年   14篇
  2003年   10篇
  2002年   8篇
  2001年   10篇
  2000年   11篇
  1999年   4篇
  1998年   4篇
  1997年   3篇
  1992年   8篇
  1991年   10篇
  1990年   12篇
  1989年   8篇
  1988年   13篇
  1987年   6篇
  1986年   7篇
  1985年   6篇
  1984年   6篇
  1983年   9篇
  1980年   4篇
  1979年   3篇
  1978年   5篇
  1977年   5篇
  1976年   4篇
  1975年   5篇
  1974年   3篇
  1973年   7篇
  1972年   9篇
  1971年   3篇
  1970年   4篇
  1969年   5篇
  1968年   5篇
  1966年   9篇
  1965年   5篇
  1958年   5篇
  1957年   4篇
  1956年   3篇
排序方式: 共有378条查询结果,搜索用时 15 毫秒
1.
Seasonal dynamics and demographic structure was studied in 15 dominant ground beetle species in the mountain taiga and mountain forest-steppe belts of the Eastern Sayan (Okinskoe Plateau). Life cycles of the dominant ground beetle species were classified by developmental time, seasonal dynamics, and intrapopulation groups with different reproduction timing. The strategies of carabid life cycles adapted to severe mountain conditions of the Eastern Sayan were revealed.  相似文献   
2.
3.
The efficacy of lipid peroxidation inhibition by the natural antioxidant alpha-tocopherol and 2,2,5,7,8-pentamethyl-6-hydroxy-chromane (PMC), a derivative without hydrocarbon tail, as well as by the synthetic antioxidant 4-methyl-2,6-diterbutyl phenol (BHT) and its phospholipid derivative was studied in the membranes of rat liver microsomes and mitochondria. The presence of hydrocarbon tail in the antioxidant molecule determines the decrease of antioxidant efficiency in biomembranes. PMC and BHT exert a destructive effect on biomembranes, leading to an increase in their permeability to ions. This evidence suggests that the presence of hydrocarbon tail in the molecules of natural antioxidants provides not only for a relatively high antioxidant efficiency but also for a structural stability of biomembranes.  相似文献   
4.
5.
By means of fluorescent method biogenic amines in the thymus tissue basophils have been investigated in intact and immunized rats and, simultaneously, in the peripheral blood of the immunized animals the hemolysins titer has been defined as an index of the immune response of the organism. In the immunized rats the number of the tissue basophils is increasing, there are many degranulated forms among them. Hence, the antigenic stimulation facilitates to the tissue basophils secretory activation, which is morphologically manifested as their degranulation. The hemolysins titer level in the peripheral blood is gradually decreasing, as the time of immunization increases. The content of biogenic amines in the tissue basophils does not undergo similar changes.  相似文献   
6.
Complications due to antibiotic therapy in rheumatic patients subjected to season bicillin prophylaxis in Minsk within 1965--1975 and in patients with extensive collagenoses were studied. Allergic complications mainly ih the form of allergic reactions in the patients treated with bicillin-3 or picillin-5 were observed in 7.8--16.8 per cent of the patients. Within 10 years 52 cases of anaphylactic shock due to the bicillin use were recorded. Side reactions to antibiotics were observed in 16 (17.3 per cent) out of 92 patients with extensive collagenoses. For prophylaxis of the above complications it is recommended to use rational antibiotic therapy in rheumatic patients, strict registration of allergological states in the anamnesis, testing of microbial sensitivity to the antibiotics.  相似文献   
7.
8.
In studying hemocoagulation in dogs under conditions of Frunze (760 m above the sea level) and Tuya-Ashu (3200 m above the sea level) it was shown that in the "emergency" phase of adaptation (the first three days) there was seen activation of fibrinolysin and profibrinolysin with depression of antifibrinolysins and inhibitors of profibrinolysin activators. The concentration of plasma fibrinogen at that period decreased by 100 mg%, which could promote an increase in the vascular permeability and improvement of oxygen approach to the tissues. Later, along with elevation of fibrinolysin and profibrinolysin activators there was a marked increase in the level of fibrinolysis inhibitors. Correlation of all the fibrinolysis components was established at a new level.  相似文献   
9.
Characteristics of rhythmogenic pacemakers of the ureter's perirenal middle and peribladder region morphologically and electrophysiologically are analysed in guinea pigs both in presence of spreading activity and breach of conductivity. It was shown that the action potential's amplitude of the middle region is the highest and duration of the spike activities from perirenal zone is maximal and all three regions are characterised by different functional conditions.  相似文献   
10.
Microbiological technology for the enhancement of oil recovery based on the activation of the stratal microflora was tested in the high-temperature horizons of the Kongdian bed (60 degrees C) of the Dagang oil field (China). This biotechnology consists in the pumping of a water-air mixture and nitrogen and phosphorus mineral salts into the oil stratum through injection wells in order to stimulate the activity of the stratal microflora which produce oil-releasing metabolites. Monitoring of the physicochemical, microbiological, and production characteristics of the test site has revealed large changes in the ecosystem as a result of the application of biotechnology. The cell numbers of thermophilic hydrocarbon-oxidizing, fermentative, sulfate-reducing, and methanogenic microorganisms increased 10-10 000-fold. The rates of methanogenesis and sulfate reduction increased in the near-bottom zone of the injection wells and of some production wells. The microbial oil transformation was accompanied by the accumulation of bicarbonate ions, volatile fatty acids, and biosurfactants in the formation waters, as well as of CH4 and CO2 both in the gas phase and in the oil. Microbial metabolites promoted the additional recovery of oil. As a result of the application of biotechnology, the water content in the production liquid from the test site decreased, and the oil content increased. This allowed the recovery of more than 14000 tons of additional oil over 3.5 years.  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