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   7805篇
  免费   280篇
  国内免费   16篇
耳鼻咽喉   86篇
儿科学   146篇
妇产科学   104篇
基础医学   944篇
口腔科学   171篇
临床医学   847篇
内科学   1803篇
皮肤病学   98篇
神经病学   502篇
特种医学   274篇
外科学   1125篇
综合类   154篇
一般理论   8篇
预防医学   585篇
眼科学   141篇
药学   544篇
中国医学   24篇
肿瘤学   545篇
  2012年   657篇
  2011年   748篇
  2010年   114篇
  2009年   72篇
  2008年   668篇
  2007年   723篇
  2006年   690篇
  2005年   650篇
  2004年   626篇
  2003年   581篇
  2002年   524篇
  2001年   394篇
  2000年   531篇
  1999年   222篇
  1998年   27篇
  1997年   13篇
  1996年   11篇
  1995年   15篇
  1994年   8篇
  1993年   12篇
  1992年   5篇
  1991年   13篇
  1990年   8篇
  1989年   10篇
  1988年   12篇
  1987年   5篇
  1981年   6篇
  1959年   65篇
  1958年   98篇
  1957年   78篇
  1956年   92篇
  1955年   76篇
  1954年   86篇
  1949年   41篇
  1948年   64篇
  1947年   12篇
  1946年   7篇
  1944年   5篇
  1943年   7篇
  1942年   5篇
  1941年   5篇
  1939年   4篇
  1938年   4篇
  1937年   4篇
  1932年   4篇
  1928年   5篇
  1927年   5篇
  1926年   4篇
  1923年   4篇
  1911年   3篇
排序方式: 共有8101条查询结果,搜索用时 15 毫秒
21.
The ability of the selective non-competitive NMDA receptor blocker MK-801 and a series of new glutamate antagonists—the adamantane derivatives IEM-1754 and IEM-1857 and phencyclidine (IEM-1925)—to prevent movement disorders induced by reversive rotation in mice was studied. I.p. MK-801 at a dose of 0.15 ml and IEM-1754 at a dose of 5.0 mg/kg prevented the development of akinesia in response to reversive rotation, as effectively as scopolamine, a known agent which provides effective prophylaxis for movement diseases. IEM-1857, the quaternary analog of IEM-1754, was not effective. IEM-1925 significantly increased the responses of mice to reversive rotation, possibly because of its high activity in relation to other subtypes of glutamate receptors. These data provide evidence for the involvement of glutamatergic transmission in the mechanism of movement disorders of vestibular origin. Translated from Rossiiskii Fiziologicheskii Zhurnal imeni I. M. Sechenova, Vol. 85, No. 4, pp. 497–501, May, 1999.  相似文献   
22.
23.
Effect of intraperitoneal injection of tetrapeptide A10 (H-Tyr-D-Orn-Phe-Gly-OH), selective -opiate receptor agonist, synthetic analog of dermorphine, in a dose of 100 g/kg on DNA synthesis and protein content in the myocardium was studied in albino rats. Five injections of tetrapeptide on days 2-6 after birth caused no changes in DNA synthesis 17 days after the last injection, i. e. in 24-day rats. The number of nucleoli and their area increased. In adult males long-term (3-week) treatment with tetrapeptide A10 increased the number of nucleoli and the mean and integral optical density of isolated cardiomyocytes stained with amido black B, which probably attested to activation of protein synthesis in the myocardium. Simultaneously, the content of catecholamines in the heart increased. These data are comparable with delayed effects of k-opiate receptor agonist dinorphine A1-13 and indicate that morphogenetic properties of opioid peptides in rat myocardium are realized via the same routes.  相似文献   
24.
Different scaffolds have been designed for ligament tissue engineering. Knitted scaffolds of poly-L-lactic acid (PLLA) yarns and co-polymeric yarns of PLLA and poly(glycolic acid) (PLGA) were characterized in the current study. The knitted scaffolds were immersed in medium for 20 weeks, before mass loss, molecular weight, pH value change in medium were tested; changes in mechanical properties were evaluated at different time points. Results showed that the knitted scaffolds had 44% porosity. There was no significant pH value change during degradation, while there was obvious mass loss at initial 4 week, as well as smooth molecular weight drop of PLLA. PLGA degraded more quickly, while PLLA kept its integrity for at least 20 weeks. Young's modulus increased while tensile strength and strain at break decreased with degradation time; however, all of them could maintain the basic requirements for ACL reconstruction. It showed that the knitted polymeric structures could serve as potential scaffolds for tissue-engineered ligaments.  相似文献   
25.
Vascular endothelial growth factor is not only angiogenic, but also immunoregulatory factor. For evaluation of the possibility of its direct interaction with mouse thymocytes we studied the effect of vascular endothelial growth factor on proliferation and apoptosis of thymocytes and expression of genes for the corresponding receptor on these cells. Vascular endothelial growth factor modulated mitogen-induced proliferation of thymocytes and stimulated spontaneous apoptosis in intact thymus cells. Thymocytes express mRNA of type 2, but not type 1 vascular endothelial growth factor receptors.__________Translated from Byulleten’ Eksperimental’noi Biologii i Meditsiny, Vol. 139, No. 5, pp. 533–537, May, 2005  相似文献   
26.
Both global and segmental glomerulopathies may damage specific areas of the renal glomerulus. Diseases associated with glomerular hyperperfusion cause lesions at the vascular pole, while diseases associated with proteinuria often damage the tubular pole. Atubular glomeruli are now known to be plentiful in a variety of common renal diseases. These glomeruli are disconnected from their tubule at the tubular pole and therefore cannot participate in the production of urine. It is widely believed that the disconnection is a result of external compression by periglomerular fibrosis. However, the variable anatomy and cell populations within both the glomerulus and the beginning of the proximal tubule at the glomerulo-tubular junction may also have important roles to play in the response to damage at this sensitive site of the nephron.  相似文献   
27.
The increased acceptability and use of condoms by men in southwestern Nigeria is reflected in joking references to condoms in the comic-style popular press. Yet these references display an ambivalence about condoms that is mirrored in survey data and in interviews regarding condom use by rural Ekiti Yoruba men. This ambivalence, which is often couched in terms of health, has implications for the acceptance of government-sponsored HIV/AIDS-related educational programs. Because of the irreverence of comic-style newspapers and the 'unofficial' nature of their authority which coincides with popular attitudes about health programs, they have a credibility that could be useful in educating adolescents about sexually-transmitted diseases and HIV/AIDS.  相似文献   
28.
29.
Auesku disease virus--suid herpesvirus type I (SHV-1) genome is analyzed by the restriction fragment pattern analysis. The analyzed strains isolated in CIS countries in 1962-1992 were compared with the European strains. Genomes of field strains Arsk, Turkmenia, and Geneva differed and even lacked the restriction fragments typical of vaccine strains MK-25 or UNIIEV-18S, which agrees with the results of the neutralization test. Immunobiological characteristics of SHV-1 strains are discussed.  相似文献   
30.
Over the past 25 years, the preplacement evaluation has undergone considerable evolution under the influence of regulatory and economic pressures. Formally used by some employers to screen out applicants who might have represented the mere possibility of a future work-related injury, the modern-day preplacement evaluation is legally restricted to only two determinations: (1) whether the individual can perform essential job functions with or without accommodation and (2) whether the individual represents a direct threat to himself or herself or others. Truly enlightened companies also recognize that other benefits accrue from a properly designed, conscientiously performed preplacement evaluation, perhaps the most important of which is to promote worker health, in the certain recognition that healthy employees are more productive ones. This benefit may be the true purpose of the preplacement evaluation and its most enduring, tangible benefit.  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