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   9569篇
  免费   442篇
  国内免费   52篇
耳鼻咽喉   178篇
儿科学   368篇
妇产科学   82篇
基础医学   1371篇
口腔科学   117篇
临床医学   644篇
内科学   2279篇
皮肤病学   286篇
神经病学   736篇
特种医学   319篇
外科学   1437篇
综合类   32篇
一般理论   1篇
预防医学   254篇
眼科学   159篇
药学   682篇
中国医学   31篇
肿瘤学   1087篇
  2023年   47篇
  2022年   108篇
  2021年   181篇
  2020年   124篇
  2019年   137篇
  2018年   211篇
  2017年   181篇
  2016年   178篇
  2015年   187篇
  2014年   262篇
  2013年   290篇
  2012年   478篇
  2011年   598篇
  2010年   365篇
  2009年   343篇
  2008年   529篇
  2007年   560篇
  2006年   560篇
  2005年   618篇
  2004年   615篇
  2003年   586篇
  2002年   511篇
  2001年   164篇
  2000年   149篇
  1999年   164篇
  1998年   139篇
  1997年   109篇
  1996年   95篇
  1995年   105篇
  1994年   88篇
  1993年   86篇
  1992年   103篇
  1991年   96篇
  1990年   82篇
  1989年   97篇
  1988年   88篇
  1987年   66篇
  1986年   60篇
  1985年   72篇
  1984年   71篇
  1983年   40篇
  1982年   47篇
  1981年   34篇
  1979年   46篇
  1978年   39篇
  1977年   27篇
  1972年   31篇
  1970年   43篇
  1969年   30篇
  1968年   30篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
31.
Gorham syndrome (massive osteolysis) is a very rare tumour-like lesion characterized by progressive osteolysis. The diagnosis must be confirmed by the microscopic finding of intramedullary angioma-like vascular structures. We report a case of a 15-year-old boy with a pathological fracture in his left humerus. Imaging modalities such as magnetic resonance imaging, computed tomography, angiography and bone scintigraphy failed to disclose to tumorous lesion that filled a cavity in the left humerus. After observing the boy's progress for 6 months, a temporary diagnosis of Gorham syndrome was made, and surgical treatment was chosen. After resection of the left humeral head and the proximal one-quarter of the humerus, thorough curettage was performed in the distal humerus and an intramedullary artificial humeral head fixed with adequate success. Pathological examination of the specimen revealed intramedullary haemangioma of the humerus.  相似文献   
32.
Abstract: The Self-Rating Body Image (SRBI) test was used to determine whether the patients with eating disorders such as anorexia nervosa or bulimia showed their body image disturbance or not. The SRBI was completed by 120 subjects who consisted of 30 low weight (LW) controls, 30 normal weight (NW) controls, 30 high weight (HW) controls, 18 anorexic patients (AN) and 12 bulimic patients (BN). The AN group had a significantly greater dissatisfaction with the scales of the body shape, visceral organ and face image of the SRBI than the weight-matched LW group. The BN group had a significantly greater dissatisfaction with the visceral organ image than the weight-matched NW group. However, no significant difference in the body shape and face images between the BN and NW groups was found. Our results suggest that the anorexic patients may disturb more parts of the body image than the bulimic patients though both the anorexic and bulimic patients showed the disturbance of body image.  相似文献   
33.
Objective: The purpose of this experimental study was to investigate whether aortic stent grafting can be applied to the treatment of an esophageal cancer involving the thoracic aorta. Methods: The canine thoracic aorta was partially resected without aorta being clamped after emplacement of an endovascular stent graft. Study I; The aortic whole layer of 1 cm in length and 1/4 of the circumference was resected and was covered by a free fascia patch of the abdominal rectal muscle immediately after stent graft placement. Study II; The aortic adventitia and the outer half of the media of the same size was resected on day 3, 7,14, 21, and on day 28, after the stent graft placement. The resected portion was covered by the free fascia patch in half experimental dogs, and was uncovered in the others. Study III; The aortic adventitia and the outer half of the media of 1 cm in length and 1/2 of the circumference was resected and was uncovered on day 7 after stent graft placement. Histological examinations were performed on day 28 and at one year after aortic resection. Results: The aortic wall could be resected in all cases with no complication, except in resection of 1/2 the circumference where the aorta had become narrow. There was no difference in healing of the resected portion of the aorta between with and without fascia covering. Conclusion: An aortic endovascular stent graft could be applied to surgery for an esophageal cancer involving the aorta.  相似文献   
34.
35.
We studied the effect of UFT (a mixture of Tegafur and uracil at a ratio of 1:4) on hepatocarcinogenesis and alpha-fetoprotein (AFP) production induced by 3'-methyl-4-dimethylaminoazobenzene (3'-MeDAB) in rats. By feeding rats with 3'-MeDAB diet, serum AFP started to appear from week 2-3 and increased until week 5-7, then declined until week 10-11. This phenomenon of a transient appearance of serum AFP is called "primary reaction". After week 11 hepatoma started to develop accompanied with an enormous elevation of serum AFP level until animals die, generally before week 25. Male Donryu strain rats fed a diet containing 0.06% 3'-MeDAB for 10 weeks, and then fed the normal diet. UFT was given by a stomach tube once a day for five days a week. Blood was collected from the tail vein every other week and serum AFP was measured by Rocket electrophoresis technique. When the administration of UFT (10 mg or 20 mg/kg/day) was started simultaneously with feeding 3'-MeDAB diet, the primary reaction was somewhat suppressed, and after week 11 development of hepatoma and elevation of AFP were markedly inhibited. The administration of UFT of a high dose (40 mg/kg/day) caused the death of animals in 7 weeks probably because of its toxicity. When the administration of UFT (10 mg or 20 mg/kg/day) was started after finish of feeding 3'-MeDAB diet for 10 weeks, the drug was not effective. These results show that if the administration of UFT was commenced at the same time with feeding 3'-MeDAB diet, the hepatocarcinogenesis and AFP production are strongly inhibited.  相似文献   
36.
Summary A new sensitive HPLC method for the determination of urinary delta-aminolevulinic acid (ALA-U) was used to evaluate the relationship between blood-lead (Pb-B) and ALA-U levels in male workers exposed to lead. The differences between the ALA-U levels determined by this method (ALAU-HP) and by a colorimetric method (ALA-U-CL) are discussed. The HPLC method gave values similar to the ALA-U-CL values at high ALA-U level. However, at low blood-lead levels (58 ± 22 g/l, n = 23), the mean ALA-U-HP level corrected by urinary creatinine level was one-third of the corrected ALA-UCL level (0.83 ± 0.14 and 2.4 ± 0.5 mg/g creatinine, respectively). A significant increase of the mean corrected ALA-U-HP level was observed at 162 ± 22 g/l Pb-B (P < 0.05, n = 26), while that of ALA-UCL was observed at 245 ± 30 g/l Pb-B (P < 0.01, n = 37). The regression equation based on the logistic model fitted well to the relationship data between the Pb-B level and the percentage of the subjects with corrected ALA-U-HP above the cut-off point (1.12 mg/g creatinine) and the expected Pb-B level for 50% response was 270 g/l Pb-B, while it did not fit well to the relationship data between Pb-B level and the percentage of the subjects with corrected ALAU-CL above the cut-off point (3.5 mg/g creatinine). The maximum responses for the two sets of corrected ALA-U levels were both observed at 625 ± 25 g/l. The corrected ALA-U level by HPLC method seems to be a useful indicator for biological monitoring of exposure to lead at low levels (< 400 g/l Pb-B = health-based biological limit, WHO) as well as high ones.  相似文献   
37.
An epicutaneous application of 2,4-dinitrofluorobenzene (DNFB) to a mouse ear caused a transient skin swelling, and the repetition of the challenge enlarged the contact dermatitis. The repeated challenge with DNFB also induced eosinophil infiltration on the application site. Administration of a chymase inhibitor significantly inhibited the ear swelling as well as eosinophil accumulation. An intradermal injection of human chymase to the mouse ear also elicited transient skin swelling and eosinophil infiltration, both of which were augmented in proportion to the number of injections. Human serum albumin and heat-inactivated chymase failed to induce such skin reactions, suggesting the participation of proteolytic activity of the enzyme. In addition, chymase stimulated eosinophil migration in vitro in a concentration-dependent manner. Taken together, these observations suggest that mast cell chymase may contribute to development of the DNFB-induced dermatitis, probably by promoting eosinophil infiltration. It is therefore possible that chymase plays a role in pathogenesis of chronic dermatitis such as atopic dermatitis.  相似文献   
38.
Umino  Y.  Kohama  T.  Kohase  M.  Sugiura  A.  Klenk  H. -D.  Rott  R. 《Archives of virology》1984,81(1-2):53-65
Summary Monospecific antisera to HN and F glycoproteins of Newcastle disease virus were prepared, and their effects on the biological activities of the virus were investigated. Anti-HN serum inhibited hemagglutinating and neuraminidase activity, as well as hemolysis. Anti-F serum had no effect on hemagglutination or neuraminidase but inhibited hemolysis and virus-induced cell fusion.Anti-HN serum was highly neutralizing, while neutralization by anti-F serum was very inefficient in conventional plaque reduction tests, although both sera were estimated to contain comparable amounts of antibody reacting with the virus as indicated by complement fixation and immunodiffusion tests. The neutralizing activity of anti-F serum was greatly enhanced by the addition of anti-IgG serum or fresh guinea pig serum, whereas that of anti-HN serum was little enhanced.Anti-HN serum incorporated in the agar overlay suppressed the development of plaques to some degree, while anti-F serum had little effect. The combination of anti-HN and anti-F sera resulted in a marked decrease in the number and size of plaques, demonstrating the synergistic effect of the two species of antibody in the containment of the spread of viral infection.With 8 Figures  相似文献   
39.
Addition of various heparinoids to the lactose-introduced, water-soluble chitosan (CH-LA) aqueous solution produces an injectable chitosan/heparinoid hydrogel. In the present work, we examined the capability of the chitosan/non-anticoagulant heparin (periodate-oxidized (IO(4)-) heparin) hydrogel to immobilize fibroblast growth factor (FGF)-2, as well as the controlled release of FGF-2 molecules from the hydrogel in vitro and in vivo. The hydrogel was biodegraded in about 20 days after subcutaneous injection into the back of a mouse. When the FGF-2-incorporated hydrogel was subcutaneously injected into the back of both mice and rats, a significant neovascularization and fibrous tissue formation were induced near the injected site. These results indicate that the controlled release of biologically active FGF-2 molecules is caused by biodegradation of the hydrogel, and that subsequent induction of the vascularization occurs.  相似文献   
40.
NK1.1+ T cells are an unusual subset of TCRαβ cells distinguished by their highly restricted Vβ repertoire and predominant usage of an invariant Vα14-Jα281 chain. To assess whether a directed rearrangement mechanism could be responsible for this invariant α chain, we have analyzed Vα14 rearrangements by polymerase chain reaction and Southern blot in a panel of cloned T-T hybrids derived from thymic NK1.1+ T cells. As expected a high proportion (17/20) of the hybrids had rearranged Vα14 to Jα281. However, Vα14-Jα281 rearrangements always occurred on only one chromosome and were accompanied by other Vα-Ja rearrangements (not involving Vα14) on the homologous chromosome. These data argue that rigorous ligand selection rather than directed rearrangement is responsible for the high frequency of Vα14-Jα281 rearrangements in NK1.1+ T cells.  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