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   13317篇
  免费   596篇
  国内免费   44篇
耳鼻咽喉   108篇
儿科学   366篇
妇产科学   161篇
基础医学   1703篇
口腔科学   383篇
临床医学   983篇
内科学   3049篇
皮肤病学   157篇
神经病学   945篇
特种医学   565篇
外科学   2899篇
综合类   58篇
一般理论   1篇
预防医学   422篇
眼科学   306篇
药学   775篇
中国医学   19篇
肿瘤学   1057篇
  2022年   134篇
  2021年   241篇
  2020年   134篇
  2019年   158篇
  2018年   199篇
  2017年   166篇
  2016年   165篇
  2015年   176篇
  2014年   251篇
  2013年   348篇
  2012年   567篇
  2011年   569篇
  2010年   324篇
  2009年   252篇
  2008年   440篇
  2007年   538篇
  2006年   527篇
  2005年   543篇
  2004年   518篇
  2003年   566篇
  2002年   536篇
  2001年   508篇
  2000年   545篇
  1999年   471篇
  1998年   241篇
  1997年   148篇
  1996年   153篇
  1995年   104篇
  1994年   111篇
  1993年   104篇
  1992年   344篇
  1991年   353篇
  1990年   316篇
  1989年   320篇
  1988年   303篇
  1987年   304篇
  1986年   276篇
  1985年   263篇
  1984年   155篇
  1983年   165篇
  1982年   79篇
  1979年   143篇
  1978年   80篇
  1977年   89篇
  1975年   92篇
  1974年   91篇
  1973年   108篇
  1972年   92篇
  1971年   81篇
  1970年   69篇
排序方式: 共有10000条查询结果,搜索用时 291 毫秒
11.
12.
13.
14.
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   
15.
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   
16.
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   
17.
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   
18.
In this study, we used a novel 4-fluid nozzle spray drier to prepare composite microparticles of a water-insoluble drug, flurbiprofen (FP), and a water-soluble drug, sodium salicylate (SS), for the purpose of improving the water solubility of FP. An ethanol solution of FP and an aqueous SS solution were simultaneously introduced through different liquid passages in the 4-fluid nozzle spray drier and then spray-dried. Quantitative elemental analysis suggested that the FP/SS ratio in each composite microparticle was nearly the same as the formulation ratio. We also found that SS and FP exist in a low crystallinity state in the composite particles. Release of FP from dissolved composite microparticles was markedly improved because of an increase in the effective surface area following rapid dissolution of SS. This study shows that it is possible to prepare FP-SS composite microparticles using a 4-fluid nozzle spray drier in single process and that this can improve the ability of FP to dissolve in water.  相似文献   
19.
Between 1970 and 1985, 221 patients with coronary artery occlusive disease underwent aorto-coronary bypass (A-C bypass) and other procedures. Among these patients, 187 had A-C bypass alone and A-C bypass in addition to correction of valvular lesions or arterialization of the coronary vein, myocardial puncture by laser. The remaining 34 had surgical corrections for myocardial infarction and its complications. Subjects were 100 patients who underwent A-C bypass alone over 6 months ago and whose follow-up study could be performed in 93 survival cases [corrected]. Subsequently, 94% of the patients have met the criteria for grade I of NYHA functional capacity and have returned to normal work at a mean of 4 years and 2 months after surgery. Improved left ventricular function has been maintained postoperatively in the patients with complete revascularization. Improved operative technique, in addition to intraoperative balloon angioplasty and onlay patch grafting, have increased the patency rate (78% in 1 mm, 94% in 2 mm of coronary diameter) of the grafts with postoperative anticoagulant therapy. On the basis of our long-term observations, coronary bypass surgery, particularly in complete revascularization, provides for significant improvement in both the quality and life expectancy of patients with severe coronary heart disease. Treadmill exercise test and magnetic resonance image (MRI) were useful, non-invasive and acceptable examinations in long-term follow up.  相似文献   
20.
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