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   127492篇
  免费   11102篇
  国内免费   7890篇
耳鼻咽喉   1427篇
儿科学   1816篇
妇产科学   2484篇
基础医学   14455篇
口腔科学   2367篇
临床医学   16739篇
内科学   19175篇
皮肤病学   1118篇
神经病学   6722篇
特种医学   4335篇
外国民族医学   45篇
外科学   13450篇
综合类   20303篇
现状与发展   28篇
一般理论   21篇
预防医学   8271篇
眼科学   3227篇
药学   13394篇
  88篇
中国医学   6691篇
肿瘤学   10328篇
  2024年   399篇
  2023年   1866篇
  2022年   4666篇
  2021年   6148篇
  2020年   4469篇
  2019年   3965篇
  2018年   4233篇
  2017年   3708篇
  2016年   3461篇
  2015年   5456篇
  2014年   6911篇
  2013年   6378篇
  2012年   9394篇
  2011年   10182篇
  2010年   6543篇
  2009年   5012篇
  2008年   6595篇
  2007年   6860篇
  2006年   6554篇
  2005年   6744篇
  2004年   4691篇
  2003年   4338篇
  2002年   3952篇
  2001年   3192篇
  2000年   3125篇
  1999年   3096篇
  1998年   1769篇
  1997年   1675篇
  1996年   1466篇
  1995年   1303篇
  1994年   1105篇
  1993年   692篇
  1992年   1068篇
  1991年   871篇
  1990年   732篇
  1989年   637篇
  1988年   626篇
  1987年   557篇
  1986年   448篇
  1985年   346篇
  1984年   212篇
  1983年   163篇
  1982年   90篇
  1981年   100篇
  1980年   85篇
  1979年   117篇
  1978年   54篇
  1977年   56篇
  1975年   44篇
  1974年   45篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
Amyloidosis is a systemic disease that usually occurs in the gastrointestinal tract or in muscular or adipose tissue. Primary amyloidosis of the urinary bladder is a rare disease that can mimic bladder cancer on cystoscopic examination as well as in its clinical presentation of painless gross hematuria. This report describes a 49-year-old male with repeated painless gross hematuria, who underwent transurethral resection of a suspected bladder tumor. Pathologic examination revealed papillary urothelial hyperplasia with vascular ectasia and no signs of malignancy. Massive gross hematuria occurred 2.5 years later. Cystoscopy showed multiple papillary lesions with yellowish-brown submucosal plaques on the posterior bladder wall. A second transurethral tumor resection was performed and histologic examination revealed plasma cell infiltration and eosinophilic amorphous deposits in the subepithelial stroma and vascular wall. The deposits were positive for Congo red and apple-green birefringence under polarized light examination but negative for Masson's trichrome stain, indicating that they were not fibrotic in nature. Hence, the diagnosis of amyloidosis of the urinary bladder was confirmed. Screening for amyloidosis was negative in other organ systems and the patient has remained disease-free up to the last follow-up 4 years after the second transurethral resection. Amyloidosis should be considered in the differential diagnosis of patients with recurrent hematuria who have symptoms characteristic of bladder cancer but negative pathologic study for malignancy. Correct diagnosis relies on clinical alertness and the use of a special staining technique during pathologic examination.  相似文献   
62.
目的了解初级护士资格考试通过情况。方法采用历史性研究方法,对我校近3年参加护士资格考试的188名学生考试情况进行调查。结果护士资格考试通过率低,其中基础知识通过率在4个科目中最低。结论有必要对参加考试的考生进一步强化基础知识的训练,从而提高护士资格考试的过线率。  相似文献   
63.
64.
The effect of p.o. administration of tea on nitrosamine-induced carcinogenesis was investigated. Female A/J mice were given N-nitrosodiethylamine (NDEA) (10 mg/kg) p.o. once a week for 8 weeks and were killed 16 weeks after the last dose. More than 90% of the mice had forestomach and lung tumors. The animals had an average of 8.3 forestomach and 2.5 lung tumors/mouse. With 0.63 or 1.25% green tea infusion (12.5 g green tea leaves brewed with 1 liter of boiling water) as the sole source of drinking water for the entire experimental period, the pulmonary tumor incidence was decreased by 18 or 44%, and the tumor multiplicity was reduced by 36 or 60%, respectively. The treatments also decreased the forestomach tumor incidence by 18 or 26% and tumor multiplicity by 59 or 63%, respectively. Administration of 0.63 or 1.25% green tea infusion, either during the NDEA treatment period only or starting 1 week after the completion of NDEA treatment, also decreased the pulmonary tumor incidence and multiplicity and the forestomach tumor multiplicity. The inhibitory effects of green tea infusion were also observed in a similar experiment using a higher dosage of NDEA (20 mg/kg). Treatment of female A/J mice with a single dose (103 mg/kg) of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) resulted in the formation of pulmonary adenomas in almost all of the animals with an average of 9.3 tumors/mouse after 16 weeks. When 0.6% decaffeinated green tea or black tea extract was given during the NNK-treatment period, tumor multiplicity was reduced by 67 or 65%, respectively. When the tea extract was given after the NNK-treatment period until the end of the experiment, 0.6% green tea extract decreased the tumor incidence and multiplicity by 30 and 85%, respectively. In this protocol, 0.6% black tea extract reduced tumor multiplicity by about 63% but did not significantly affect the tumor incidence. The results clearly demonstrated an inhibitory action of green tea and black tea on nitrosamine-induced tumorigenesis.  相似文献   
65.
T lymphocytes play a fundamental role in the initiation and regulation of chronic inflammatory responses in patients with asthma. CD69 is an early marker of T‐cell activation. The levels of intercellular adhesion molecule‐1 (ICAM‐1, CD54) and L ‐selectin have been reported to increase in patients with allergic diseases and asthma. The present study was therefore undertaken to investigate the expression of CD69, CD54, and L ‐selectin by T lymphocytes of children with asthma, before and after immunotherapy. Eighteen children newly diagnosed with asthma, 11 good and nine poor responders to immunotherapy, and 16 normal subjects, were enrolled in this study. The percentages of CD69+, CD54+, and CD62L+ cells in T lymphocytes were measured by using flow cytometry. The levels of CD69, CD54, and CD62L in serum and culture supernatants were determined by using enzyme‐linked immunosorbent assay (ELISA). The expression of CD69 and CD54 on CD3+ T lymphocytes was significantly higher in children with asthma than in control patients. All the patient groups expressed (spontaneously and following stimulation with phorbol myristate acetate and ionomycin together with mite‐extract proteins) greater amounts of CD69 and CD54 than did control subjects. With long‐term immunotherapy, the percentages of CD69+ and CD54+ T lymphocytes were significantly lower in patients with a good response to immunotherapy. Our results also showed significantly lower serum L ‐selectin levels following immunotherapy. In conclusion, successful immunotherapy resulted in decreased expression and production of CD69 and CD54. These results may explain, in part, the clinical efficacy of immunotherapy.  相似文献   
66.
The effects of an externally applied direct-current electric field on the movement of cultured rabbit corneal epithelial cells and stromal fibroblasts were studied. After a latency of approximately 20 minutes in an electric field, both epithelial cells and stromal fibroblasts became spindle shaped and underwent galvanotropism by aligning their long axes perpendicular to the applied electric field. The electric field stimulus thresholds for galvanotropic movements in epithelial cells and stromal fibroblasts were 4V/cm and 6 V/cm, respectively. After an additional latency of 30 minutes, both cell types manifested galvanotaxic movements: epithelial cells commenced migration in the cathodal (downfield) direction and stromal fibroblasts in the anodal (upfield) direction. For both types of cells, ruffled membranes and lamellipodia were abundant at the leading edges of migrating cells and cell processes underwent retraction at the trailing edges. At field strengths of above 10 V/cm, evidence of cellular damage (manifested by cellular rounding and detachment), attributable to the electric field treatment, was observed after 4 hours. These preliminary results suggest that galvanotaxic responses could be exploited clinically in the enhancement of corneal wound healing.  相似文献   
67.
68.
小切口胆囊切除术108例临床观察   总被引:1,自引:0,他引:1  
本文报告腹部切口5-8cm的小切口胆囊切除术108例,与同期大切口胆囊切除术相比,具有创伤较小、恢复较快、并发症少、切口疤痕小的优点,虽不如腹腔镜胆囊切除术(LC)的疼痛轻、恢复快,但并症比LC少,只要适应症选择得当,在术者的经验和技术较成熟的情况下,不昔为一种可供选择的方法。  相似文献   
69.
70.
本文报告了1990年5月以来脑干区大型、复杂占位病变15例.其中,位于脑干内3例,脚间窝2例,岩尖部4例,全岩骨区1例,全斜坡区2例,第四脑室内3例.本组采用以扩大了的岩骨入路为主的联合入路,行肿瘤全切除8例,次全切除5例.2例仅作了活检加减压术.除1例死亡外,均恢复良好.本文结合文献,对脑干区手术入路进行了讨论.  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