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   8044篇
  免费   506篇
  国内免费   104篇
耳鼻咽喉   64篇
儿科学   189篇
妇产科学   357篇
基础医学   942篇
口腔科学   117篇
临床医学   887篇
内科学   1808篇
皮肤病学   88篇
神经病学   547篇
特种医学   561篇
外科学   1003篇
综合类   245篇
一般理论   3篇
预防医学   397篇
眼科学   158篇
药学   600篇
  1篇
中国医学   43篇
肿瘤学   644篇
  2023年   50篇
  2022年   81篇
  2021年   194篇
  2020年   94篇
  2019年   156篇
  2018年   213篇
  2017年   154篇
  2016年   125篇
  2015年   233篇
  2014年   297篇
  2013年   398篇
  2012年   592篇
  2011年   534篇
  2010年   327篇
  2009年   354篇
  2008年   476篇
  2007年   416篇
  2006年   403篇
  2005年   409篇
  2004年   372篇
  2003年   298篇
  2002年   244篇
  2001年   226篇
  2000年   194篇
  1999年   200篇
  1998年   97篇
  1997年   74篇
  1996年   77篇
  1995年   68篇
  1994年   52篇
  1993年   41篇
  1992年   115篇
  1991年   83篇
  1990年   86篇
  1989年   80篇
  1988年   89篇
  1987年   86篇
  1986年   83篇
  1985年   82篇
  1984年   70篇
  1983年   36篇
  1982年   40篇
  1981年   24篇
  1980年   26篇
  1979年   39篇
  1978年   32篇
  1977年   32篇
  1976年   26篇
  1975年   40篇
  1974年   24篇
排序方式: 共有8654条查询结果,搜索用时 0 毫秒
41.
To examine the effect of a soybean oil emulsion on essential fatty acid, lipid, and glucose metabolism, preterm infants were randomized to receive 0.5 g/kg/d lipid for 5 days (n = 10, group 1) or 0.5 increased to 2.0 g/kg/d over 5 days (n = 11, group 2). Triene/tetraene ratios did not change in group 1, but decreased in group 2. In both groups, plasma phospholipid linoleate (percent and micrograms per milliliter) increased, the increase being greater in group 2. In both groups, percent content of arachidonate and 5,8,11-eicosatrienoate decreased, and that of oleate remained unchanged. In contrast, absolute content of arachidonate and oleate tended to increase, and that of 5,8,11-eicosatrienoate remained unchanged. At a lipid intake of 0.5 g/kg/d, no infants had hyperlipemia. When lipid intake exceeded 1.0 g/kg/d, the frequency of hypertriglyceridemia (triglycerides greater than 200 mg/dL) and free fatty acidemia, with the free fatty acid/molar albumin ratio exceeding 6:1, increased. Plasma glycerol increased slightly, but was substantially less than the rise in enzymatically determined triglycerides. Hyperglycemia was self-limiting and did not require alteration in dextrose intake. Thus, (1) infusion of a soybean oil emulsion at 0.5 to 2.0 g/kg/d maintains essential fatty acid status and phospholipid arachidonate concentrations; (2) significant hyperlipemia occurs when lipid intake exceeds 1.0 g/kg/d; (3) hyperglycemia associated with lipid infusion tends to be self-limiting and may not require alteration in lipid or dextrose intake; and (4) enzymatically determined triglycerides may be used to monitor lipid tolerance, provided that allowance is made for a small but systematic overestimation resulting from the rise in plasma glycerol.  相似文献   
42.
Ectodomain shedding of epidermal growth factor receptor ligands such as transforming growth factor- alpha (TGF-alpha), heparin-binding epidermal growth factor-like growth factor (HBEGF), and amphiregulin (AREG) is considered to be important during implantation. Tumor necrosis factor-alpha converting enzyme (TACE) has been suggested as the major sheddase for these molecules. The objectives of this study are (1) to characterize the expression of TACE in the human placenta throughout gestation; (2) to determine the association between the expression of TACE with TGF-alpha, HBEGF, and AREG; (3) to ascertain whether TACE mediates TGF-alpha, HBEGF, and AREG shedding; and (4) to examine the effect of hypoxia on the expression of TACE. By analyzing a total of 55 villous samples representing different gestational ages, the authors found that TACE was continuously expressed in the placentas throughout gestation and that the levels of TACE were positively correlated with the levels of TGF-alpha, HBEGF, and AREG. Preadministration of a TACE inhibitor in villous explant cultures or transfection of cytotrophoblastic cells with TACE-specific small interference RNA decreased the shedding of HBEGF and AREG. Moreover, hypoxia (2% O(2)) caused an increase in the levels of TACE mRNA and protein in villous explants and primary cytotrophoblastic cells in vitro. These results indicate that oxygen regulates the expression of TACE and that TACE may be important for placental development during human pregnancy.  相似文献   
43.

Purpose

To analyze the gap junction proteins connexin 37 (Cx37) and connexin 43 (Cx43) after subcutaneous transplantation of cryopreserved mouse ovarian tissue.

Methods

Expression of gap junction genes was assessed by immunohistochemistry and real-time polymerase chain reaction (PCR) in transplanted cryopreserved ovarian tissue compared with that of normal ovarian tissue. Apoptosis of ovarian cells was evaluated by using the terminal deoxynucleotidyl transferase-mediated biotinylated deoxyuridine triphosphates nick end-labeling method.

Results

After subcutaneous transplantation, Cx37 and Cx43 mRNA and protein expression were significantly lower in cryopreserved than in normal ovarian tissue. Apoptosis was increased in granulosa cells from antral follicles of the cryopreserved tissue.

Conclusion

After cryopreservation and subcutaneous transplantation of ovarian tissue, proteins forming gap junctions between oocytes and granulosa cells are under-expressed compared with normal controls.  相似文献   
44.
45.
46.
47.
Journal of Neuroimmune Pharmacology - Recent studies show that proinflammatory cytokines might be related to the development of opioid dependence (physiological, psychological, or both). In a...  相似文献   
48.
49.
This study explored the predictors of medication adherence among Taiwanese people with major depression and dysthymic disorder. Previous research indicates that depressed patients vary in compliance with their medication regimen. Poor compliance reduces the therapeutic effect of medication. Self-report questionnaires were used for this cross-sectional study conducted with 181 outpatients diagnosed with major depression or dysthymic disorder. About 50% of depressed patients reported good medication adherence. The predictors of adherence were patient income, treatment efficacy, and understanding the importance of continuing medication. Professionals should use collaborative communication and cultural values clarification with depressed patients and their families to improve the awareness of illness and to increase the likelihood of medication compliance.  相似文献   
50.
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