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   45977篇
  免费   2154篇
  国内免费   375篇
耳鼻咽喉   475篇
儿科学   843篇
妇产科学   1316篇
基础医学   5456篇
口腔科学   1723篇
临床医学   3555篇
内科学   12869篇
皮肤病学   934篇
神经病学   4024篇
特种医学   1238篇
外科学   6926篇
综合类   172篇
一般理论   9篇
预防医学   2472篇
眼科学   721篇
药学   2481篇
中国医学   117篇
肿瘤学   3175篇
  2024年   41篇
  2023年   326篇
  2022年   781篇
  2021年   1474篇
  2020年   801篇
  2019年   1124篇
  2018年   1569篇
  2017年   1028篇
  2016年   1128篇
  2015年   1333篇
  2014年   1814篇
  2013年   2395篇
  2012年   3661篇
  2011年   3616篇
  2010年   2041篇
  2009年   1779篇
  2008年   3077篇
  2007年   3202篇
  2006年   2990篇
  2005年   2958篇
  2004年   2664篇
  2003年   2405篇
  2002年   2131篇
  2001年   298篇
  2000年   234篇
  1999年   327篇
  1998年   379篇
  1997年   335篇
  1996年   297篇
  1995年   281篇
  1994年   221篇
  1993年   169篇
  1992年   169篇
  1991年   122篇
  1990年   125篇
  1989年   101篇
  1988年   82篇
  1987年   65篇
  1986年   76篇
  1985年   81篇
  1984年   78篇
  1983年   72篇
  1982年   99篇
  1981年   66篇
  1980年   72篇
  1979年   42篇
  1978年   49篇
  1977年   37篇
  1976年   37篇
  1974年   30篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
Background Optic disc anomalies are frequently associated with Alagille syndrome. We report here the first case of a patient with Alagille syndrome combined with optic pit and serous macular detachment. Methods A male patient with Alagille syndrome was referred from the pediatric hepatology department for investigation of visual loss in the right eye. Anterior segment examination showed evidence of posterior embryotoxon, confirmed by gonioscopic evaluation. Dilated fundus examination revealed serous macular detachment and optic pit. Results OCT 3 scans confirmed the clinical findings. Conclusions Optic pit is uncommon and should prompt a search for genetic disorders or development abnormalities. The association between the two syndromes in this patient might be due to failure of correct neuroectodermal development, for which a common genetic pathway is likely.  相似文献   
62.
63.
64.
Abstract: A 20-year-old woman and her 12-year-old brother had hypohidrotic ectodermal dysplasia, cleft lip and palate, midfacial hypoplasia with narrow nose from the nasal bridge to the tip, narrow dysplastic nails, and conical teeth and hypodontia, and hypospadias and hypoplastic uvula in the boy. The woman had major underdevelopment of intellectual capacity. The most important hair anomalies in both siblings were sparse eyebrows, pili torti, and pili canaliculi. Some of the pili canaliculi had two canals (pili bicanaliculi), and the cross section for scanning electron microscopy had a quadrangular aspect. This is the seventh family reported with Rapp-Hodgkin ectodermal dysplasia.  相似文献   
65.
Transglutaminase (TGase) activity was reduced in intact mitogen-stimulated human peripheral blood lymphocytes (PBL) when compared to intact resting PBL. Moreover, a treatment of the same quiescent immunocompetent cells with purified liver TGase and Ca2+ completely suppressed the mitogen-induced blast transformation. A decrease in TGase activity in neoplastically transformed seminal vesicle epithelial cells with respect to their normal parent counterpart was also observed. Our data support the notion of a possible implication of TGase in cell proliferation and transformation.  相似文献   
66.
The xanthine, hypoxanthine, and total oxypurine levels were determined in the CSF of 28 hydrocephalic patients (age from newborn to 2 years) and 8 healthy controls using HPLC. The Evans' index, the mean weekly increase in cranial circumference, and the intracranial pressure were also measured. Of the hydrocephalic patients 13 were self-compensated and the other 15 had a shunt implanted during the course of the study. The mean xanthine, hypoxanthine, and total oxypurine levels in the normal children were 5.20, 5.94, and 11.29 mol/l, respectively. In the self-compensated hydrocephalics these levels were 5.17, 5.71, and 10.79 mol/l, respectively. In the noncompensated hydrocephalics, they were 9.90, 9.91, and 19.82 mol/l. The differences between the latter group and the first two are statistically significant (P<0.001). The mean Evans' index and the mean weakly increase in cranial circumference in the self-compensated hydrocephalics were 0.35 and 0.25 cm, respectively. In the noncompensated hydrocephalics, they were 0.55 and 0.95 cm. The differences between the two groups are statistically significant (P<0.001). Two weeks after implantation of shunts in the noncompensated cases, the mean xanthine, hypoxanthine, and total oxypurine levels fell to 4.22, 4.57, and 8.80 mol/l, respectively. These changes are statistically significant (P<0.001). We think that the two criteria (clinical and biochemical) are equally useful for the prediction of self-compensation in hydrocephalic children and that the oxypurine values after shunt implantation can be used to monitor progress in noncompensated cases.  相似文献   
67.
Summary Up-to-date unsatisfactory results obtained in multimodality treatments of malignant glioma have prompted the research of new therapeutic modalities with unconventional modes of action. Lonidamine (LND) is a drug which reduces aerobic glycolytic activity in both human and experimental tumors. This effect mainly depends on the inhibition of mitochondrially-bound hexokinase (HK) which is present in large amounts in malignant cells. A Phase II study was conducted on patients with recurrent glioma; 12 patients were admitted to the study. Clinical side effects were moderate, necessitating a reduction of the dosage in only 1 case. The objective results were evaluated according to the indications of Levin. 2 responders and 3 cases of stable disease were observed out of 10 evaluable patients. The potential value of this new drug is discussed.  相似文献   
68.
Voltage-clamp experiments have been performed on ovulated Xenopus laevis oocytes. Two kinds of oocytes were studied: mature oocytes presenting the white spot due to germinal vesicle breakdown (GVBD) were found to be essentially unexcitable; oocytes without the white spot appeared to possess ionic channels which open transiently on hyperpolarization. The current is carried by chloride ions and, in Holtfreter's solution, has a reversal potential at approximately - 15 mV.  相似文献   
69.
70.
We report the capacity of CD40 ligand (CD40L)-negative T cell clones to activate human B cells. CD40L-negative T cells induce a level of B cell proliferation 10–20% of that seen with normal T cells. The signal provided by the negative clones is synergistic with that derived from a CD40L transfectant, and restores B cell proliferation to normal levels, showing that CD40L-negative T cell clones are not inherently inhibitory for B cells. Although their capacity to induce proliferation was much reduced, CD40L-negative T cell clones were still strong inducers of B cell differentiation to plasma cells. This differentiation to plasma cells was inhibited by a CD40L transfectant. The data are discussed with regard to the normal in vivo mechanism for maintaining B cell memory and memory antibody responses to T-dependent antigens.  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