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   13335篇
  免费   1231篇
  国内免费   46篇
耳鼻咽喉   81篇
儿科学   470篇
妇产科学   353篇
基础医学   1763篇
口腔科学   377篇
临床医学   1577篇
内科学   2597篇
皮肤病学   132篇
神经病学   1053篇
特种医学   584篇
外科学   1971篇
综合类   393篇
一般理论   11篇
预防医学   1543篇
眼科学   141篇
药学   850篇
  2篇
中国医学   8篇
肿瘤学   706篇
  2021年   180篇
  2020年   107篇
  2019年   192篇
  2018年   223篇
  2017年   170篇
  2016年   173篇
  2015年   211篇
  2014年   265篇
  2013年   412篇
  2012年   605篇
  2011年   629篇
  2010年   325篇
  2009年   321篇
  2008年   524篇
  2007年   612篇
  2006年   533篇
  2005年   512篇
  2004年   494篇
  2003年   455篇
  2002年   449篇
  2001年   407篇
  2000年   503篇
  1999年   443篇
  1998年   176篇
  1997年   159篇
  1996年   186篇
  1995年   179篇
  1994年   150篇
  1993年   150篇
  1992年   321篇
  1991年   324篇
  1990年   348篇
  1989年   320篇
  1988年   274篇
  1987年   277篇
  1986年   251篇
  1985年   274篇
  1984年   183篇
  1983年   149篇
  1980年   103篇
  1979年   157篇
  1978年   129篇
  1977年   113篇
  1976年   107篇
  1975年   96篇
  1974年   124篇
  1973年   116篇
  1972年   116篇
  1971年   114篇
  1970年   104篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
71.
72.
73.
Germinomas are the most common type of germ cell tumor occurring commonly before the second decade of life. Because of the radiosensitivity of germinomas, traditional treatment following diagnosis has been conventional radiotherapy. The desire to defer radiotherapy to avoid the delayed neurocognitive effects has led researchers to investigate the use of up front chemotherapy. A major limitation in using chemotherapy for brain tumors has been the inability to deliver drugs across the blood brain barrier. The blood brain barrier consortium has developed chemotherapy protocols for patients with malignant brain tumors through the use of reversible osmotic opening of the blood brain barrier. While the patient is under general anesthesia, osmotic opening or disruption is achieved by a 30-second intracarotid infusion of mannitol. The mannitol infusion is followed by both intraarterial and intravenous chemotherapy. By administering chemotherapy in conjunction with blood brain barrier disruption, drug delivery to the tumor and the brain around tumor is increased.  相似文献   
74.
We present an adenoid cystic carcinoma of the base of tongue in a 48-year-old male with a restricted chromosomal alteration by cytogenetic and spectral karyotypic analysis (SKY). SKY and G-banding analyses identified the t(6;14)(q25;q13) as the sole structural aberration in all metaphases analyzed. This finding supports a critical role for this event in the development of this tumor. The implications of chromosome 6q translocation in this case and in previously reported adenoid cystic carcinomas are highlighted and discussed.  相似文献   
75.
76.
77.
Gangliosides were isolated from human cataractous nuclei by solvent extraction, dialysis, and thin-layer chromatography and compared to gangliosides present in human whole normal and cataractous lenses. Three predominant gangliosides were tentatively identified as GM1, GM3, and GD1a, and several other resorcinol-positive components were observed in each of the sets of lens tissue. Thin-layer chromatographic patterns were similar, although some minor and possibly significant differences in band intensities were observed when chromatograms of gangliosides from cataractous nuclei and cataractous whole lenses were visually compared with those of whole normal lenses. Total ganglioside extracts were methanolyzed and the fatty acid methyl esters extracted with hexane and resolved by gas chromatography. Nervonic acid (C-24:1) content was increased in cataractous nuclei as compared to normal and cataractous whole lenses.  相似文献   
78.
Human insulin-receptor gene   总被引:16,自引:0,他引:16  
S Seino  M Seino  G I Bell 《Diabetes》1990,39(2):129-133
The human insulin-receptor (hINSR) gene spans a region of greater than 120,000 base pairs (bp) on the short arm of chromosome 19. It is comprised of 22 exons or coding regions that vary in size from 36 to greater than 2500 bp. To a large degree, the introns appear to divide the hINSR gene into segments that encode structural and/or functional elements of the hINSR protein. The exon-intron organization of the hINSR gene provides a clue to the evolutionary history of this gene and suggests that it is a mosaic constructed from protein-coding regions recruited from other genes. Eight mutations in the hINSR gene that result in expression of structurally abnormal proteins have been described. These mutations are associated with insulin resistance and provide insight into the role of the hINSR gene in the development of diabetes mellitus.  相似文献   
79.
Whilst HLA matching is routine for renal transplantation, the possible benefits of matching donor and recipient age have not been previously examined. In this study we examined the simultaneous effect of donor to recipient age difference on the graft survival of 141 consecutive first cadaver transplant recipients treated by cyclosporin immunosuppression. Multivariate regression analysis, taking into account other variables of moderately matched recipients (i.e. dialysis time and type, donor/recipient sex, local/imported kidneys, recent sensitivity, total ischaemic time, preoperative transfusions), indicated that age-difference was the single most important variable (P less than 0.05). Individually there was no significant effect of recipient age, whilst older donors (aged greater than 50 years) were associated with significantly worse graft survival than those younger (P less than 0.01). When dealing with donors aged greater than or equal to 50 years the corresponding recipient 1-year graft was improved when the donor was no more than 5 years older than the transplant recipient. Donor age to recipient age difference is a potentially important selection criterion in renal transplantation.  相似文献   
80.
The new oral hypoglycemic agent SDZ 51641 was evaluated in nondiabetic rats and a rat model of human non-insulin-dependent diabetes mellitus. Diabetes was induced with a single injection of 37.5 mg/kg streptozocin, and the rats exhibited hyperglycemia in the fed state with normal insulin levels. Treatment of nondiabetic animals with 100 mg/kg SDZ 51641 given orally significantly decreased serum glucose and ketone levels within 4 h without affecting insulin levels. Nonesterified fatty acids increased more than twofold during the same period. Its effect on ketone and fatty acid levels suggests that SDZ 51641 acts as an inhibitor of fatty acid oxidation. Diabetic rats treated with SDZ 51641 exhibited a significant acute hypoglycemic response, which was more pronounced after 3 days of treatment. The compound also significantly decreased serum cholesterol and triglyceride levels 27 and 53%, respectively. When endogenous hepatic glucose production was assessed in nondiabetic and diabetic animals via continuous infusion of [3-3H]glucose, we found that hepatic glucose production was elevated 43% in diabetic compared with control animals. When diabetic rats were treated with 100 mg/kg SDZ 51641, hepatic glucose production decreased to normal levels within 6 h. Hyperinsulinemic-euglycemic clamp studies indicated that SDZ 51641 had no effect on insulin-stimulated glucose utilization. Measurement of [1-14C]oleate oxidation in isolated hepatocytes demonstrated that SDZ 51641 inhibited long-chain fatty acid oxidation in a concentration-dependent manner. The compound was ineffective at inhibiting long-chain fatty acid oxidation in epitrochlearis or soleus muscles.(ABSTRACT TRUNCATED AT 250 WORDS)  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