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   19067篇
  免费   880篇
  国内免费   102篇
耳鼻咽喉   159篇
儿科学   449篇
妇产科学   179篇
基础医学   2435篇
口腔科学   535篇
临床医学   1303篇
内科学   4586篇
皮肤病学   310篇
神经病学   1210篇
特种医学   808篇
外科学   3837篇
综合类   86篇
一般理论   1篇
预防医学   655篇
眼科学   389篇
药学   1172篇
中国医学   54篇
肿瘤学   1881篇
  2023年   96篇
  2022年   231篇
  2021年   364篇
  2020年   199篇
  2019年   252篇
  2018年   292篇
  2017年   283篇
  2016年   306篇
  2015年   316篇
  2014年   423篇
  2013年   572篇
  2012年   926篇
  2011年   941篇
  2010年   547篇
  2009年   465篇
  2008年   798篇
  2007年   942篇
  2006年   939篇
  2005年   971篇
  2004年   927篇
  2003年   968篇
  2002年   917篇
  2001年   566篇
  2000年   593篇
  1999年   554篇
  1998年   331篇
  1997年   221篇
  1996年   238篇
  1995年   157篇
  1994年   149篇
  1993年   143篇
  1992年   372篇
  1991年   372篇
  1990年   336篇
  1989年   355篇
  1988年   326篇
  1987年   315篇
  1986年   287篇
  1985年   276篇
  1984年   173篇
  1983年   173篇
  1982年   90篇
  1979年   146篇
  1978年   85篇
  1977年   93篇
  1975年   99篇
  1974年   93篇
  1973年   109篇
  1972年   93篇
  1971年   81篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
CYP2E1 and ALDH2 Genotypes and Alcohol Dependence in Japanese   总被引:2,自引:0,他引:2  
The genotypes of the CYP2E1 and ALDH2 loci of alcoholic (alcohol dependence) and nonalcoholic (healthy) Japanese were investigated to examine the relationship between the polymorphism of CYP2E1 (C1/C2) and ALDH2 ( ALDH2*1/ALDH2*2 ), and the susceptibility to alcoholism. There was no significant difference in C2 gene frequency between alcoholics (0.19) and nonalcoholics (controls) (0.20), whereas there was a significant difference in ALDH2 allele frequency, suggesting that, in Japanese, the C2 genotype of CYP2E1 may have nothing to do with the risk of developing alcohol dependence. However, the ALDH2*1 allele may influence drinking behavior and the development of alcohol dependence. Furthermore, racial interethnic differences in the frequency of the mutated allele of the CYP2E1 gene (CJ were found, like the ALDH2 gene. Japanese healthy controls showed a significantly higher frequency of the C2 allele than did Swedish healthy controls (0.05; reported by Persson et al., FEBS Lett. 319:207-211,1993).  相似文献   
12.
A 70-year-old woman developed left hypoglossal nerve palsy, a right hemiparesis sparing the face, and a typical left Wallenberg's syndrome. These symptoms resulted from a lesion in the left half of the medulla oblongata, suggesting Babinski-Nageotte syndrome, a rare cerebrovascular disease. This is the first case of ischemic infarction in the territory of the left vertebral artery and posterior inferior cerebellar artery demonstrated on magnetic resonance imaging. Severe bilateral lesions of the distal vertebral arteries demonstrated on digital subtraction angiography may have contributed to the development of this syndrome.  相似文献   
13.
14.
15.
16.
Studies were carried out on the penetration of cefuzonam (L-105, CZON), a new synthetic cephalosporin antibiotic, into cerebrospinal fluid, and on the clinical efficacy against bacterial infections. The results are summarized as follows: Concentrations of CZON in cerebrospinal fluid at 1 hour after intravenous administration of 100 mg/kg in cases of furunculosis of the external canal, encephalitis and mumps meningitis were 0.56 micrograms/ml, 1.44 micrograms/ml and 0.33 micrograms/ml, respectively. Concentrations of CZON in cerebrospinal fluid at 1 hour after intravenous administration of 100 mg/kg in 3 cases of purulent meningitis were 2.80-6.40 micrograms/ml at the acute stage and 0.56-1.45 micrograms/ml even at the recovering stage. Sensitivities of clinically isolated strains to CZON were determined and expressed as MIC. MICs of CZON on Haemophilus influenzae, Escherichia coli, Proteus mirabilis and Klebsiella pneumoniae were similar to MIC's of cefmenoxime (CMX), and lower than those of cefoperazone (CPZ), cefmetazole (CMZ), cefatiam (CTM) and Cefazolin (CEZ). The MIC of CZON on Staphylococcus aureus was similar to those of CEZ, CMZ and CTM, and lower than those of CMX and CPZ. Clinical responses of CZON were good in 2 cases of purulent meningitis, good in 2 cases of pyothorax, excellent in 1 case of septicemia, excellent in 3 cases of urinary tract infections, excellent in 7 cases and good in 3 cases out of 10 cases of pneumonia. Clinical responses of other diseases were excellent in 4 cases of bronchitis, good in 1 case of furunculosis of the external canal, excellent in 1 case of tonsillitis. No side effects nor abnormal laboratory findings were observed except 2 cases of mild diarrhea out of 24 cases.  相似文献   
17.
Stability of cardiac function and myocardial intracellular ionic composition was examined in the Krebs-perfused isolated rat working heart. Hearts perfused by a conventional Krebs solution showed stable contraction for 2 h, but during this period, intracellular ionic environment (Na, K, Ca) substantially changed. Addition of dextran to the perfusate inhibited, though not completely, this time-dependent deterioration and made the heart less vulnerable to the hypoxia-reoxygenation.  相似文献   
18.
Four enantiomers (3a-d) of the title compound, YM-09730 (3), were synthesized by the reaction of (-)- or (+)-5-(methoxycarbonyl)-2, 6-dimethyl-4-(m-nitrophenyl)-1,4-dihydropyridine-3-carboxylic acid (1a or 1b) with (S)- or (R)-1-benzyl-3-pyrrolidinol (2a or 2b). [3H]Nitrendipine binding affinity and coronary vasodilating activity of these compounds were evaluated. The absolute configuration of the most potent enantiomer (3a) with the longest duration was unequivocally determined to be (S)-1,4-dihydropyridine-C4 and (S)-pyrrolidine-C3 (S,S) by X-ray crystallographic study on 3a X HBr as well as 3a X HCl. The configuration of 1a corresponds to R, and the other enantiomers of 3 were respectively determined by chemical correlation. The potency order of the four enantiomers was (S,S)-3a greater than (S,R)-3b greater than (R,R)-3d greater than (R,S)-3c. Latent chiral characters of nifedipine derivatives with the identical ester groups were assigned by comparison of their puckering modes of 1,4-dihydropyridine (DHP) rings with those found in 3a X HCl or 3a X HBr. On the basis of the assignment, it has been revealed that the (S)-DHP nifedipine derivatives possess the synperiplanar carbonyl group at C5. The conformational restriction may be a factor causing stereoselectivity of antagonism.  相似文献   
19.
A 44-year-old women developed marked myopathy one year earlier, when she was treated with intravenous prednisolone for acute severe exacerbation of ulcerative colitis. When she was admitted to our hospital for another severe exacerbation, intravenous cyclosporine A was administered as monotherapy because she could not tolerate corticosteroid. The treatment was successful and she obtained complete remission. Cyclosporine A monotherapy is considered to be a valuable alternative to proctocolectomy for severe ulcerative colitis patients who cannot tolerate corticosteroid.  相似文献   
20.
Pancreatic metastasis of malignant melanoma is rarely diagnosed while the patient is alive. We report a case of metastatic melanoma of the pancreas in a 35-year-old woman presenting with a solid mass of the pancreas. Her past medical history included a radical hysterectomy 2 years previously for malignant melanoma of the vagina. Twelve months later, lung metastasis was also resected. EUS-guided fine needle aspiration (EUS-FNA) identified that the pancreatic tumor was histologically and immunohistochemically identical to the surgical specimen of her lung neoplasm. Imaging studies including US, CT, and MRI have limited value to distinguish the tumors from primary ductal adenocarcinoma. EUS-FNA can provide tissue diagnosis from pancreatic masses, specifically when other modalities have failed.  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