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   4359篇
  免费   167篇
  国内免费   17篇
耳鼻咽喉   52篇
儿科学   52篇
妇产科学   61篇
基础医学   493篇
口腔科学   77篇
临床医学   260篇
内科学   1379篇
皮肤病学   78篇
神经病学   273篇
特种医学   99篇
外科学   607篇
综合类   10篇
一般理论   1篇
预防医学   90篇
眼科学   23篇
药学   432篇
中国医学   14篇
肿瘤学   542篇
  2022年   40篇
  2021年   76篇
  2020年   41篇
  2019年   47篇
  2018年   42篇
  2017年   53篇
  2016年   66篇
  2015年   69篇
  2014年   104篇
  2013年   111篇
  2012年   179篇
  2011年   227篇
  2010年   124篇
  2009年   117篇
  2008年   197篇
  2007年   214篇
  2006年   221篇
  2005年   196篇
  2004年   217篇
  2003年   179篇
  2002年   205篇
  2001年   122篇
  2000年   161篇
  1999年   170篇
  1998年   48篇
  1997年   35篇
  1996年   45篇
  1995年   31篇
  1994年   32篇
  1993年   41篇
  1992年   114篇
  1991年   80篇
  1990年   86篇
  1989年   95篇
  1988年   80篇
  1987年   89篇
  1986年   47篇
  1985年   72篇
  1984年   53篇
  1983年   44篇
  1982年   21篇
  1981年   18篇
  1979年   46篇
  1975年   28篇
  1973年   20篇
  1972年   22篇
  1970年   22篇
  1969年   19篇
  1968年   22篇
  1966年   21篇
排序方式: 共有4543条查询结果,搜索用时 15 毫秒
81.
A 44-year-old patient progressed from nonalcoholic fatty liver (NAFL) to nonalcoholic steatohepatitis (NASH) cirrhosis. She was diagnosed with NAFL via a liver biopsy. At 56 years old, she was diagnosed with NASH stage 3 via a second liver biopsy. One year later, she was diagnosed with NASH cirrhosis via a third liver biopsy. This is the first study to report the gradual deterioration of liver histology shown via three liver biopsies and fibrosis markers in a patient who progressed from NAFL to NASH cirrhosis. Following menopause, it is necessary to be aware of the rapid development of liver fibrosis.  相似文献   
82.
83.
Ethanol exerts damaging effects on gastric mucosa and delays ulcer healing. To investigate the effect of ethanol on the wound repairing process, we used a wound repair model using primary cultured gastric mucosal cells. A confluent monolayer gastric mucosal cell sheet consisting mainly of mucous cells was wounded to make a cell-free area of constant size. Cell-free area was restored with time after wounding and monitored every 12 hr using a computer image analyzer to observe epithelial cell restoration quantitatively in the presence and absence of ethanol (2.0%). It was found that, although the control wound was completely repaired in 36 to 48 hr, the group treated with 2.0% ethanol showed a significant delay of repair. In the control, 5-bromodeoxyuridine-positive cells appeared around the wound in 24 to 36 hr. In contrast, the group treated with 2.0% ethanol showed no 5-bromodeoxyuridine-positive cells during the experiment. In conclusion, 2.0% ethanol retarded the repair of gastric mucosal restoration by inhibiting the initial gastric cell migration, followed by inhibition of proliferation of cells.  相似文献   
84.
85.
Reactions of thioureylene antithyroid drugs (1-methyl-2-mercaptoimidazole and carbimazole) with hypochlorous acid (HOCl) and superoxide were followed optically and products were analyzed by mass spectrometry. 1-methyl-2-mercaptoimidazole (MMI) and carbimazole reacted rapidly with HOCl with a rate constant of 1 x 10(7) and 7 x 10(6) M(-1)s(-1), respectively. The characteristic spectrum assigned to MMI disulfide appeared immediately after addition of HOCl, followed by a slow conversion to a final spectrum. The conversion was dependent upon the ratio of HOCl to MMI and both antithyroid drugs uptake 3 moles HOCl for complete conversion. A similar sequence of spectral changes was also observed when the HOCl was replaced by myeloperoxidase (MPO)/H2O2/Cl- system. The final oxidation product of MMI and carbimazole with HOCl and superoxide was 1-methylimidazole.  相似文献   
86.
BACKGROUND AND AIM: Usually, bacteria are cryopreserved for short-term storage at low and ultra-low temperatures. There are no reports as to whether Helicobacter pylori is a fragile bacteria when stored at low and ultra-low temperatures as compared with other intestinal bacteria. A study was done on seven H. pylori strains and other intestinal bacteria to compare different temperatures for storage of organisms in saline solution. METHODS: Seven H. pylori strains, specifically American Type Culture Collection (ATCC) strains 43504 and TN2GF4, and five strains isolated from the present patients were grown on a modified Skirrow's agar for H. pylori. Escherichia coli and Bacteroides distasonis, both representing isolates from the present patients, were grown on trypticase soy blood agar for E. coli, and EG agar for B. distasonis. Culture was for 4-5 days under microaerobic, aerobic and anaerobic conditions at 37 degrees C. Cells were harvested by scraping growth from the solid medium and into sterile saline. The cells were adjusted to concentrations of 109 viable cells/mL in saline and preserved at 4 degrees C, -20 degrees C, or -80 degrees C for 3 weeks before reculture under microaerobic, aerobic and anaerobic conditions at 37 degrees C for 7 days. After incubation, morphologically distinct colonies were counted, isolated, and identified by standard bacteriologic techniques. The H. pylori were morphologically analyzed by electronic microscopy before and after preservation. Mongolian gerbils were inoculated with the cryopreserved H. pylori to evaluate the bacterial infectivity. RESULTS: Six of the seven H. pylori strains failed to culture after being preserved at 4 degrees C, -20 degrees C, or -80 degrees C. Only ATCC 43504 could be cultured after freezing at -80 degrees C. The number of H. pylori ATCC 43504 before preservation was 9.0 +/- 0.5 (log10 no. organisms/mL) and decreased to 5.7 +/- 0.6 after preservation. Morphologically, all H. pylori except ATCC 43504 strains transformed from a bacillary to a coccoid form after preservation. In addition, none of the H. pylori strains could infect Mongolian gerbils after preservation. Escherichia coli and B. distasonis were recovered. Titers before and after 4 degrees C, -20 degrees C, and -80 degrees C, respectively, were 9.1 +/- 0.2, 8.9 +/- 0.5, 8.6 +/- 0.3, and 8.7 +/- 0.3 for E. coli and 9.1 +/- 0.4, 8.7 +/- 0.6, 8.6 +/- 0.5, and 8.8 +/- 0.3 for B. distasonis. CONCLUSIONS: Helicobacter pylori is a fragile bacteria for storage at low and ultra-low temperatures in comparison with other intestinal bacteria.  相似文献   
87.
The purpose of this study was to evaluate whether the existence of coronary collateral circulation influences recanalization rates of intracoronary thrombolysis. The study population consisted of 85 consecutive patients undergoing intracoronary thrombolysis within 6 hours after the onset of the first acute myocardial infarction, all of whom had a complete occlusion of the infarct-related coronary artery. Intracoronary thrombolysis with high-dose urokinase (960,000 IU) was attempted at a rate of 24,000 IU/min. Of 18 patients (group A) who had good angiographic collateral circulation to the area perfused by the infarct-related coronary artery, the obstructed artery was recanalized to a residual luminal diameter stenosis of less than or equal to 90% (successful recanalization) in only five (28%). In contrast, of 67 patients (group B) with poor or no collateral circulation, recanalization was successful in 40 (60%) (p less than 0.05). Antegrade flow of infarct-related arteries was observed following thrombolysis in 12 (67%) of 18 group A patients and in 56 (84%) of 67 group B patients (p = NS). It was concluded that (1) the presence of collaterals correlates with the presence of high-grade stenosis; (2) the presence of collaterals correlates with the presence of high-grade stenosis; (2) the presence of collaterals is inversely related to the efficacy of thrombolytic therapy; and (3) the difference in successful recanalization rates observed between the two groups probably reflects the impact of underlying stenosis severity on the effectiveness of lytic therapy.  相似文献   
88.
Hemorrhage into a pancreatic pseudocyst is a rare event, but is the most rapidly lethal complication of chronic pancreatitis. Visceral-vessel aneurysms are an unexpectedly common finding in arteriography of patients with chronic pancreatitis. This case report describes bleeding from an anterior superior pancreaticoduodenal artery aneurysm, caused by chronic pancreatitis. The aneurysm was successfully treated by embolization with a steel coil.  相似文献   
89.
OBJECTIVE: An endostatin that inhibits angiogenesis dependent tumor growth is being tested as an antitumor agent. The neoangiogenesis condition of cancer is essentially identical to that of rheumatoid arthritis (RA). Thus antiangiogenic treatment has potential for treatment of RA. We investigated the effects of human recombinant endostatin on human RA synovial tissue by use of a novel model of RA, in which human RA tissue is grafted into SCID mice (SCID-HuRAg). METHODS: Ten or 50 mg/kg of human recombinant endostatin was administered by percutaneous direct intrasynovial injection in each of 7 SCID-HuRAg mice. We examined the volume of the grafted tissue mass and the histological changes 7 days after endostatin administration. Six control mice received phosphate buffered saline in the same manner. RESULTS: The grafted synovial volume of SCID-HuRAg mice was significantly decreased by endostatin administration. The number of inflammatory cells (macrophages and lymphocytes) was also significantly reduced in a dose dependent manner. The number of vessels that were counted by von Willebrand factor VIII and type IV collagen positive cells was decreased, although apoptotic cells were increased in RA synovia. CONCLUSION: The results suggest that antiangiogenesis treatment using endostatin represents a potential new therapeutic strategy for RA.  相似文献   
90.
Summary. We report the case of a 2-year-old Japanese boy with acute favism who was treated with human haptoglobin products. He had been exhibiting chronic nonspherocytic haemolytic anaemia until the diagnosis of glucose-6-phosphate dehydrogenase (G6PD) deficiency when 14 months old. He suffered a favic crisis at 24 months of age, when the administration of haptoglobin was effective for relieving bilirubinaemia and haemoglobinuria. Serum-free Hb rapidly decreased to normal levels despite the sustained level of serum lactate dehydrogenase. His G6PD gene was G6, Guadalajara. This is the first application of haptoglobin therapy for acute favism and the first reported case of Japanese G6PD deficiency with typical favic crisis. Haptoglobin treatment might be helpful for managing the haemolytic crisis in the disease.  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