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   479496篇
  免费   21319篇
  国内免费   888篇
耳鼻咽喉   6811篇
儿科学   17365篇
妇产科学   15720篇
基础医学   68632篇
口腔科学   12934篇
临床医学   38575篇
内科学   88487篇
皮肤病学   10642篇
神经病学   32019篇
特种医学   21733篇
外国民族医学   139篇
外科学   74047篇
综合类   8824篇
现状与发展   1篇
一般理论   161篇
预防医学   35434篇
眼科学   11054篇
药学   33751篇
  3篇
中国医学   962篇
肿瘤学   24409篇
  2018年   7041篇
  2017年   6472篇
  2016年   6216篇
  2015年   8258篇
  2014年   8790篇
  2013年   10582篇
  2012年   18635篇
  2011年   14097篇
  2010年   8301篇
  2009年   9300篇
  2008年   10673篇
  2007年   12219篇
  2006年   12313篇
  2005年   19885篇
  2004年   21016篇
  2003年   16271篇
  2002年   11126篇
  2001年   17254篇
  2000年   15229篇
  1999年   16690篇
  1998年   3529篇
  1997年   3054篇
  1996年   2964篇
  1995年   2902篇
  1992年   14468篇
  1991年   14804篇
  1990年   14821篇
  1989年   14347篇
  1988年   13121篇
  1987年   12693篇
  1986年   12144篇
  1985年   11249篇
  1984年   8025篇
  1983年   6768篇
  1982年   3382篇
  1980年   2771篇
  1979年   7927篇
  1978年   5408篇
  1977年   4389篇
  1976年   3930篇
  1975年   5136篇
  1974年   6213篇
  1973年   5925篇
  1972年   5692篇
  1971年   5511篇
  1970年   5237篇
  1969年   4905篇
  1968年   4646篇
  1967年   4413篇
  1966年   4054篇
排序方式: 共有10000条查询结果,搜索用时 16 毫秒
991.
OBJECTIVE: The use of Kirschner wire for the fixation of premaxilla is a well-known method in bilateral cleft lip surgery. We report a case in which the Kirschner wire of the premaxillary fixation had migrated intrasphenoidally. RESULTS AND CONCLUSIONS: The foreign body was accidentally discovered during a cephalometric analysis and was taken out surgically through an upper lip sulcus incision. Although the wire remained asymptomatic for 10 years, it constituted a potential danger for intracranial migration.  相似文献   
992.
To differentiate between relapse of infection and reinfection of the urinary tract due to Klebsiella pneumoniae, 33 K. pneumoniae isolates collected from 20 patients with spinal cord injury (SCI) over 2 years were typed by genomic fingerprinting by repetitive-element PCR. Clinical isolates obtained from the same patients with recurrent episodes of urinary tract infection (UTI) revealed identical genomic fingerprints indicating relapse of UTI due to K. pneumoniae, despite appropriate antibiotic therapy. Seventeen isolates obtained from 8 of the 20 SCI patients shared a common genotype, termed RD6. Among non-SCI patients residing in other nursing units, the RD6 genotype was found in 5 of 10 patients with K. pneumoniae UTI but in only 1 of 20 patients with K. pneumoniae infection that did not involve the urinary tract, suggesting a strong association of this genotype with UTI. All RD6 isolates exhibited strong adherence (> or =50 adherent bacteria per cell) to HEp-2 cells, whereas other K. pneumoniae isolates generally did not adhere to or adhered very weakly to HEp-2 cells (< or =5 adherent bacteria per cell). Adherence was inhibited either by 4% D-mannose or by anti-type 1 fimbrial rabbit serum. These results suggest that the capacity of K. pneumoniae RD6 isolates to cause UTI may be mediated by its striking adherence to mammalian cells.  相似文献   
993.
994.
Thirty-two castrated male crossbred growing pigs (average initial wt 26.9 kg) were used to determine the effect of a high level of dietary protein (37%) compared with a normal level of protein (15%) on enterobacteria and Campylobacter sp. inhabitation in the large intestine and on visceral organ hypertrophy and the interrelationships between these two factors. Pigs were kept in pairs (eight pens of two pigs/diet) and fed their respective diets and libitum. Eight pigs (two pens of two pigs fed each diet) were killed at wk 4, 8, 12 and 16 without fasting. Fecal samples were obtained every 2 wk from animals scheduled for necropsy at 16 wk, and colon contents were obtained from all pigs at necropsy; samples were enumerated individually for enterobacteria and Campylobacter sp. Weights of heart, lungs, liver, kidneys, perirenal fat and empty stomach, small intestine and large intestine were recorded at necropsy. Stomach, cecum and proximal colon were sectioned for histopathologic examination. Daily body weight gain was depressed by high dietary protein, but liver and kidneys were heavier in the high protein group than in controls at each time interval. Mild lymphoid hyperplasia of Peyer's patches in the small intestine in some pigs in both groups was indicative of antigenic stimulation but not of pathologic significance. There was no effect of diet on counts of enterobacteria or Campylobacter sp. in feces or colon contents during the 16-wk experiment. We conclude that the hypertrophic response of the tissues of growing pigs to high dietary protein is not the result of the presence of Campylobacter sp. or enterobacteria in the colon contents.  相似文献   
995.
Thermal injury is known to induce dysregulation of the immune system; however, the precise mechanisms have to be clarified. We investigated the histamine release of basophil granulocytes from severely burned patients (n = 12) after stimulation with anti-IgE or the Ca-ionophore A 23187, respectively. The anti-IgE-induced basophil histamine release of all patients was reduced in comparison to healthy donors beginning at day one postburn (p.b.) (5.0 +/- 2.3% vs. 30.5 +/-3.4%), while the Ca-ionophore-induced release was not decreased before day two p.b. Basophils of patients who finally succumbed to their injuries showed poor responsiveness (to zero levels) over the total time. In contrast, the basophil releasability of surviving patients returned to nearly normal levels (fifth to seventh week p.b.). Already in the second week p.b. there was a significant difference in histamine release between survivors and nonsurvivors [e.g., days 6-9 p.b.: 23.7 +/- 4.0 vs. 6.9 +/- 2.7 (p less than 0.005) after Ca-ionophore stimulation]. The altered basophil histamine release was neither due to a diminished dose- or a delayed time-response to the stimuli nor due to differences in the basophil counts or the cellular histamine content. Our data indicate that the decrease of the basophil releasability, which may be secondary to altered signal transduction pathways in severely burned patients correlates with the clinical outcome.  相似文献   
996.
The paper is a survey of investigations into radioactive contamination of selected plant and animal species (bioindicators) which have the capacity for multiple accumulation of fission products. Literature data on the contamination of bioindicators are compared with special reference to the accumulation of 131I, 137Cs and 90Sr as a result of atmospheric nuclear experiments and the nuclear accident at Chernobyl.  相似文献   
997.
The kinetics of inhaled methyl ethyl ketone (MEK) at a concentration of 200 ppm for four hours were studied in volunteers after swallowing ethanol at a dose of 0.8 g/kg. Ethanol was given either before or at the end of the exposure to MEK. The blood concentrations of MEK, 2-butanol, and 2,3-butanediol were monitored during and after the exposure. MEK concentrations in exhaled air and MEK and 2,3-butanediol concentrations in urine were also measured. Ethanol inhibited the primary oxidative metabolism of MEK and caused an increase in the blood concentrations of MEK and 2-butanol after ingestion. Ethanol ingestion, through higher blood MEK concentrations, also increased the elimination of MEK in the urine and exhaled air. Ethanol taken before exposure to MEK reduced the serum concentration of 2,3-butanediol initially but there was an increase about eight hours after the exposure. Urinary excretion of 2,3-butanediol followed the same pattern. Prior ingestion of ethanol thus seemed to interfere with the metabolism of 2,3-butanediol during and after exposure to MEK.  相似文献   
998.
The author presents his experience of surgical treatment of 63 high congenital dislocations of the hip in schoolchildren. Osteotomy of the pelvis after Salter in combination with shortening osteotomy and open reduction of the hip has been used. Aseptic necrosis of the femoral head in the postoperative period has been revealed in almost 80% of the cases; the results were good during the first 10 years of observations in 28.5% and bad in 31% of the cases; after 10 and more years the percentage of good results fell to 18%. However, the patients gave a higher estimation of the treatment results as the period of clinical compensation of the operated joints lasted 10 to 12 pears, which made easier their contacts with schoolmates and family creation in future.  相似文献   
999.
O P Khanna  J H Loose 《Urology》1990,36(2):139-142
Three patients with interstitial cystitis diagnosed on the basis of clinical symptoms, classic endoscopic findings, and a typical histologic picture were treated with intravesical doxorubicin. All 3 patients showed remarkable improvement, as manifested by complete clearance of irritative bladder symptoms and healing of ulceration. Doxorubicin therefore may be the breakthrough drug for interstitial cystitis.  相似文献   
1000.
C G Stief  H Gall  W Scherb  W B?hren 《Urology》1990,36(2):143-145
Two patients with a history of penile prosthesis removal presented for non-prosthetic treatment of their erectile dysfunction. The first patient had a penile implant for two years before it was removed and showed extensive cavernosal fibrosis. He did not respond to intracavernosal injection of vasoactive drugs. The second patient had the prosthesis for four weeks. He showed no evidence of cavernosal fibrosis and responded well to the intracavernous injection. He has been in an intracavernous autoinjection program for more than one year without complications.  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