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   105728篇
  免费   654篇
  国内免费   887篇
  107269篇
  2021年   90篇
  2020年   100篇
  2019年   92篇
  2018年   11996篇
  2017年   10813篇
  2016年   7715篇
  2015年   926篇
  2014年   715篇
  2013年   857篇
  2012年   4710篇
  2011年   13291篇
  2010年   12305篇
  2009年   8463篇
  2008年   10161篇
  2007年   11766篇
  2006年   688篇
  2005年   930篇
  2004年   1353篇
  2003年   1429篇
  2002年   1155篇
  2001年   543篇
  2000年   391篇
  1999年   211篇
  1998年   108篇
  1992年   259篇
  1991年   251篇
  1990年   187篇
  1989年   218篇
  1988年   249篇
  1987年   254篇
  1986年   210篇
  1985年   248篇
  1984年   208篇
  1983年   181篇
  1982年   87篇
  1979年   234篇
  1978年   153篇
  1977年   140篇
  1976年   135篇
  1975年   168篇
  1974年   266篇
  1973年   262篇
  1972年   490篇
  1971年   518篇
  1970年   263篇
  1969年   243篇
  1968年   185篇
  1967年   189篇
  1966年   166篇
  1965年   136篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
101.
Results of investigations carried out in a 500-person group of patients with stoma and their practical applications are discussed. 1. Despite operational shock, the majority of patients is able to adopt to the new situation and develop different life-style. 2. Rehabilitation facilities pre-operational management and provides an information on stoma before surgery. Postoperative management should consider psychosocial aspects of the stoma. 3. An important role in rehabilitation process play: preparation of the patients' families before the surgery including information on the diagnosis, prognosis and planned therapy. 4. Persons who underwent the same surgery and continue active life may favourably contribute to the postoperational care of patients with stoma. Activity of so-called patients clubs plays also positive role.  相似文献   
102.
103.
An effect of the treatment with guanfacine on the activity of the adreno-sympathetic system, beta-thromboglobulin, beta-endorphin, and blood lipids was studied in 30 patients with the primary arterial blood hypertension. It was found that guanfacine significantly decreases plasma noradrenaline, adrenaline, and dopamine. Moreover, it decreases the excretion of noradrenaline, adrenaline and 4-hydroxy-3-methoxy-phenylglycol. These effects correlate with the drop in both systolic and diastolic blood pressure. A decrease in plasma renin activity was also observed. It correlated with the blood pressure drops. Guanfacine increased beta-endorphin levels while beta-thromboglobulin, total cholesterol and triglycerides levels remained unaffected. The authors suggest that the hypotensive effect of guanfacine is related to the decrease in adreno-sympathetic system activity and plasma renin activity and no effect on the erythrocyte activity and lipids metabolism.  相似文献   
104.
Under tolerance, evoked by multiple doses of pethidine (PD), the serum and brain tissue content of PD was related to diminished analgesic activity. Even though in tolerant rats no enhancement of PD biotransformation in the liver could be recognized (as followed by the measurement of hepatic esterase and N-demethylase activity), the amounts of both PD and nor-PD excreted in urine were increased under tolerance. The authors conclude that the faster disposition of PD may contribute to the development of tolerance.  相似文献   
105.
Most of the biological processes in the living organisms of both animals and man are known to be of rhythmical nature. Variability of enzymatic activity in circadian cycle depends on many factors among other on age, sexual maturity, diet as well as medication. The results obtained in our studies indicate, that the activity changes of acid phosphatase and ATP-ase Mg++ dependent in the liver of all the examined age groups were of 24 hour circadian rythm. As to the acid phosphatase activity the results of this experiments showed that in circadian cycle in all examined age groups there is only one peak of elevated activity. ATP-ase Mg++ dependent showed two activity peaks appearing at the same hour both in 30 and 60 days old animals. It should be noticed that the activities of ATP-ase Mg++ dependent in 100 day old animals were two times higher than in 30 and 60 days old rats.  相似文献   
106.
Majority of pituitary tumours secrete one of the named hormones: PRL, GH, ACTH, proopiomelanocortine, alpha and beta subunit of TSH, LH, and FSH. Some of those tumours secrete two or more hormones. The aim of this study was to determine the effect of bromocriptine (Parlodel MR and LAR) upon secretion of hormones and tumour size in 10 patients with mixed pituitary tumours. In all patients pituitary and peripheral hormones, CT scan and visual fields were examined before and after treatment with bromocriptine: Parlodel MR and LAR. Bromocriptine treatment decreased PRL secretion in all 10 patients; GH--in all 6 in whom it was increased; TSH--in 2, FSH--in 2 and alpha-subunit in all 6 in whom they were increased. In 5 patients treatment resulted in shrinkage of the tumour mass by 20 to 35%. In all examined subjects clinical improvement was achieved. Our results demonstrate that bromocriptine (Parlodel MR and LAR) is very effective and well tolerated in the treatment of patients with mixed pituitary tumours particularly those with hyperprolactinemia.  相似文献   
107.
Activity of methemoglobin reductase was studied in human red cells treated with methylguanidine and guanidinosuccinic acid in concentrations similar to those in plasma of patients with chronic renal failure. Enzyme activity was measured with Richterich technique following an incubation at 37 degrees C for three hours. Results have shown that methylguanidine in concentration of 5.4 x 10(-5) mol/l decreases activity of methemoglobin reductase in human red cells on average by 13.9%. Higher concentrations potentiate this effect. Similar changes in methemoglobin reductase activity were noted after introduction of guanidine-succinic acid into the mixture. This agent in concentration 5.6 x 10(-5) mol/l inhibited activity of the tested enzyme by 34.2% on average. Combined methylguanidine in concentration of 5.4 x 10(-5) mol/l and guanidine-succinic acid in concentration of 2.8 x 10(-5) mol/l inhibited methemoglobin reductase activity by 33.0% on average. It may be suggested, that methylguanidine and guanidine-succinic acid being low molecular uremic toxins may significantly decrease methemoglobin reductase activity in red cells of patients with chronic renal failure.  相似文献   
108.
Administration of drugs such as fenfluramine, 20-40 mg/kg, and m-chlorophenylpiperazine (m-CPP), 2.5-5 mg/kg, which release serotonin or activate postsynaptic serotonin receptors, respectively, induced a dramatic decrease in the duodenal content of immunoreactive dynorphin (ir-DYN). The effect was antagonized by cyproheptadine, 1 mg/kg. Similarly, acute administration of the specific serotonin reuptake blockers fluvoxamine, 15 mg/kg, or femoxetine, 10 mg/kg, and 5-hydroxytryptophan (5-HTP), 40-160 mg/kg, evoked a marked decrease in the duodenal content of ir-DYN. A combined administration of fluvoxamine or femoxetine and 5-HTP failed to potentiate the effect of individual treatment. Only a higher dose of fenfluramine, 40 mg/kg, increased the ir-DYN content in the hypothalamus. These results suggest that the brain and gut ir-DYN is independently regulated by the serotonin system and that a serotonin mechanism might stimulate release of the gut dynorphin content.  相似文献   
109.
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