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   1469篇
  免费   93篇
  国内免费   4篇
耳鼻咽喉   19篇
儿科学   33篇
妇产科学   20篇
基础医学   160篇
口腔科学   3篇
临床医学   186篇
内科学   195篇
皮肤病学   23篇
神经病学   130篇
特种医学   33篇
外科学   190篇
综合类   11篇
一般理论   5篇
预防医学   240篇
眼科学   13篇
药学   220篇
肿瘤学   85篇
  2023年   10篇
  2022年   18篇
  2021年   47篇
  2020年   20篇
  2019年   35篇
  2018年   36篇
  2017年   38篇
  2016年   25篇
  2015年   42篇
  2014年   51篇
  2013年   76篇
  2012年   114篇
  2011年   110篇
  2010年   73篇
  2009年   48篇
  2008年   72篇
  2007年   66篇
  2006年   77篇
  2005年   68篇
  2004年   75篇
  2003年   54篇
  2002年   37篇
  2001年   15篇
  2000年   12篇
  1999年   19篇
  1998年   12篇
  1997年   8篇
  1995年   12篇
  1994年   7篇
  1993年   10篇
  1992年   19篇
  1991年   20篇
  1990年   16篇
  1989年   15篇
  1988年   15篇
  1987年   15篇
  1986年   17篇
  1985年   10篇
  1984年   17篇
  1983年   10篇
  1981年   5篇
  1980年   12篇
  1979年   7篇
  1977年   7篇
  1976年   6篇
  1975年   5篇
  1974年   7篇
  1973年   8篇
  1972年   9篇
  1971年   5篇
排序方式: 共有1566条查询结果,搜索用时 10 毫秒
1.
2.
3.
In certain Japanese macaque (Macaca fuscata) populations, females routinely engage in same-sex courtship, mounting, and consortship activity. Drawing on behavioral, biogeographic, and genetic research, we suggest that female homosexual behavior may be associated with genetically distinct free-ranging populations of Japanese macaques. In addition, we briefly discuss the implications of this research for the evolution of female homosexual behavior in this species.  相似文献   
4.
We assessed the inter-rater reliability of the 100-point International Cooperative Ataxia Rating Scale (ICARS). Three neurologists independently rated videotaped ICARS examinations of 22 subjects with genetically determined ataxias (spinocerebellar ataxia [SCA] Type 1 in 11; SCA Type 2 in 1; Friedreich's ataxia in 10) and 4 controls. Scores on live ICARS assessment had ranged from 0 to 7 for controls and 11 to 74 for ataxic subjects (clinically very mildly affected to wheelchair-bound). Inter-rater correlation was very high for the total score (Kendall's omega 0.994, 95% confidence interval, 0.988-0.997), and high to very high for each component subscore (0.791 for speech to 0.994 for posture/gait). All correlations were significant at P < 0.00001. The ICARS exhibits very high inter-rater reliability even without prior observer standardisation and is sensitive to a range of ataxia severities from very mild to severe.  相似文献   
5.
A high dose combination chemotherapy regimen (CBV) consisting of cyclophosphamide (1.5 gm/m2 day 1 to day 4); BCNU (300 mg/m2 day 1) and etoposide (100 mg/m2 every 12 hours for 6 doses), followed by bone marrow transplant from human leukocyte antigen (HLA) identical sibling donors, was evaluated in 29 patients in whom acute leukemia was in relapse or remission. Engraftment of donor cell type occurred in all but one of 21 patients, in whom marker differences between donor and recipient were established. Two of 11 patients transplanted during relapse of the disease, lived beyond 1 year after bone marrow transplantation. One patient died free of leukemia, 41 months after transplantation of meningitis. Two of seven patients transplanted during the second remission of the disease, are alive and free of leukemia at 42+, and 8+ months. All patients transplanted during the third or fourth remission of the disease have died from either a further relapse, or transplant related causes. The low incidence of organ toxicity with CBV allows for further dose escalation of its drug components.  相似文献   
6.
Between July 1, 1976, and June 30, 1986, at the Henrietta Egleston Hospital for Children, 2,242 infants and children underwent palliation or repair of a congenital heart defect. Twenty-one (0.94%) of these patients developed mediastinitis following a median sternotomy. Nineteen of these twenty-one patients had required cardiopulmonary bypass. All patients had positive mediastinal cultures. The first 8 patients were managed traditionally by debridement and irrigation. Three of these patients suffered serious metabolic complications related to the povidone-iodine irrigant, which resulted in 1 death. Another patient died from persistent sepsis following debridement. Subsequently, 13 patients were managed by early debridement and rotation of the pectoralis major or rectus abdominis muscle flaps, or both. Following muscle flap rotation and early wound closure, 2 patients had subsequent incisional complications. One patient had incisional dehiscence and 1 had a superficial skin separation. Two deaths in this group, 28 and 51 days, respectively, following muscle flap rotation, resulted from nonincisional problems in patients with healed median sternotomies. The group having muscle flap rotation required a significantly shorter duration of postoperative ventilatory support (3.2 versus 24 days, p less than 0.05) and a significantly shorter confinement in the intensive care unit (6.2 versus 33 days, p less than 0.01). Also, the physiological and physical trauma of continued wound care in the awake child was minimized in the group with muscle flap rotation.  相似文献   
7.
Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) protein levels increase in particulate fractions in association with cell death in HEK293 cells, S49 cells, primary thymocytes, PC12 cells, and primary cerebral cortical neuronal cultures. Subcellular fractionation and immunocytochemistry reveal that this increase primarily reflects nuclear translocation. Nuclear GAPDH is tightly bound, resisting extraction by DNase or salt treatment. Treating primary thymocytes, PC12 cells, and primary cortical neurons with antisense but not sense oligonucleotides to GAPDH prevents cell death. Because cell-death-associated nuclear translocation of GAPDH and antisense protection occur in multiple neuronal and nonneuronal systems, we propose that GAPDH is a general mediator of cell death and uses nuclear translocation as a signaling mechanism.  相似文献   
8.
Oral glucocorticoids are widely used to treat exacerbations of asthma and COPD. A role for their use in treating exacerbations in Cystic Fibrosis (CF) is not proven. We describe the current practice, amongst UK adult CF physicians, of oral glucocorticoid use as an adjuvant to intravenous (IV) antibiotic treatment during CF pulmonary exacerbation (P EX). The survey also examined whether physicians thought a randomised controlled trial (RCT) was necessary and their willingness to participate patients in such a trial. Eighty one percent of physicians replied. All of them used corticosteroids with P EX. Most physicians supported the need for a RCT and would be willing to enroll consenting patients in the trial. This survey highlighted the need for a RCT which would examine the role of adjuvant corticosteroids to IV antibiotics in CF P EX.  相似文献   
9.
The effects of quercetin on viability and proliferation of Chinese Hamster Ovary (CHO) cells and CHO cells overexpressing human quinone reductase (CHO+NQO1) were studied to investigate the involvement of the pro-oxidant quinone chemistry of quercetin. The toxicity of menadione was significantly reduced in CHO+NQO1 cells compared to wild-type CHO cells, validating the NQO1-overexpression in the CHO+NQO1 transfectant. Quercetin inhibited the proliferation of wild-type CHO and CHO+NQO1 cells to a similar extent without affecting cell viability, indicating that NQO1 enrichment of CHO cells did not provide increased protection. On the other hand, inhibition of NQO1 in both types of cells by dicoumarol significantly potentiated the inhibitory effect of quercetin on cell proliferation, revealing the role of NQO1 in cellular protection against quercetin. Altogether, these results can be explained by the hypothesis that both wild-type CHO and CHO+NQO1 cells contain sufficient NQO1 activity for optimal protection against the pro-oxidant effect of quercetin on cell proliferation. The results also point at a cellular NQO1 threshold for optimal protection against quercetin. This NQO1 threshold seems to be in the range of NQO1 activities already present in various tissues.  相似文献   
10.
Ammonium perchlorate (AP) and sodium chlorate (SC) have been detected in public drinking water supplies in many parts of the United States. These chemicals cause perturbations in pituitary-thyroid homeostasis in animals by competitively inhibiting iodide uptake, thus hindering the synthesis of thyroglobulin and reducing circulating T(4) (thyroxine). Little is known about the short-term exposure effects of mixtures of perchlorate and chlorate. The present study investigated the potential for the response to a mixture of these chemicals on the pituitary-thyroid axis in rats to be greater than that induced by the individual chemicals. Adult male F-344 rats were exposed, via their drinking water, to the nominal concentrations of 0.1, 1.0, 10 mg/L AP or 10, 100, 1000 mg/L SC and their mixtures for 7 days. Serum T(4) levels were significantly (p < 0.05) reduced in rats following exposure to the mixtures, but not after exposure to the individual chemicals. Serum T(3) (triiodothyronine) was not altered by treatment and TSH (thyroid stimulating hormone) was only increased after the high-dose chlorate treatment. Histological examination of the thyroid gland showed colloid depletion and hypertrophy of follicular epithelial cells in high-dose single chemical and all mixture-treated rats, while hyperplasia was observed only in some of the rats treated with mixtures (AP 10 + SC 100, AP 0.1 + SC 1000, and AP 10 + SC 1000 mg/L). These data suggest that short-term exposure to the mixture of AP and SC enhances the effect of either chemical alone on the pituitary-thyroid axis in rats.  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