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   64538篇
  免费   4720篇
  国内免费   213篇
耳鼻咽喉   802篇
儿科学   1431篇
妇产科学   858篇
基础医学   8245篇
口腔科学   979篇
临床医学   6851篇
内科学   14013篇
皮肤病学   807篇
神经病学   6489篇
特种医学   2194篇
外国民族医学   5篇
外科学   11610篇
综合类   625篇
一般理论   48篇
预防医学   4427篇
眼科学   1229篇
药学   4431篇
中国医学   71篇
肿瘤学   4356篇
  2024年   51篇
  2023年   458篇
  2022年   750篇
  2021年   2017篇
  2020年   1213篇
  2019年   1805篇
  2018年   2208篇
  2017年   1539篇
  2016年   1642篇
  2015年   1891篇
  2014年   2719篇
  2013年   3389篇
  2012年   5294篇
  2011年   5492篇
  2010年   2959篇
  2009年   2713篇
  2008年   4426篇
  2007年   4514篇
  2006年   4310篇
  2005年   4101篇
  2004年   3667篇
  2003年   3489篇
  2002年   3121篇
  2001年   436篇
  2000年   334篇
  1999年   403篇
  1998年   626篇
  1997年   494篇
  1996年   384篇
  1995年   334篇
  1994年   299篇
  1993年   271篇
  1992年   220篇
  1991年   171篇
  1990年   146篇
  1989年   118篇
  1988年   125篇
  1987年   109篇
  1986年   105篇
  1985年   94篇
  1984年   126篇
  1983年   106篇
  1982年   113篇
  1981年   101篇
  1980年   117篇
  1979年   56篇
  1978年   55篇
  1977年   48篇
  1976年   38篇
  1974年   41篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
61.
The optimal allocation of cadaveric kidneys for transplantation with reference to human leukocyte antigen (HLA) match and sharing these organs to a distant center remains controversial. The current analysis was performed using the United Network for Organ Sharing (UNOS) database for cadaveric kidney transplants (Tx) between 1988 and 1997. The graft survivals of zero-mismatch (matched) kidneys with the mate (mismatched) kidneys were compared. There were 2385 donors and 4770 Tx. Significant differences in recipient demographics between matched and mismatched Tx were: fewer African-American race (AA) in the matched group (9.0% vs. 21.9%), higher number of previous Tx (25.5% vs. 14.8%) and elevated mean cold ischemia time (24.0 vs. 22.2 h). Post-Tx dialysis requirements were similar (22.8% vs. 24.1%, p = 0.62) and matched kidneys had to travel more distance (920 vs. 232 miles). Using a Cox model, the matched group had a decreased relative hazard of graft failure of 23.0% (p = 0.0002) or 35% (p < 0.0001) with and without censoring for death. There was significantly better graft survival in the matched recipients in all pairs except AA (matched) and non-AA (mismatched). For older donors (> or = 50 years, n = 1508), the matched grafts survival was marginally significant (p =0.05). Matched kidneys have improved survival compared with the mismatched kidneys despite the longer distance traveled. The benefit of mismatched transplants was predominantly seen in non-AA.  相似文献   
62.
63.
Autism is associated with epilepsy. One third of the population of people with autism have developed seizures in early adult life. In spite of this well-known association, little is known about the treatment of epilepsy in autism. This paper reviews the sparse literature and reports a systematic case-record study of the treatment of epilepsy in autism. Some practical guidelines for clinicians are provided. Research in the field of epilepsy in autism is highly warranted.This study has been supported by a grant from The Commission for Social Research, Sweden, No. E 88/170:2.  相似文献   
64.
BACKGROUND: Pearly penile papules are angiofibromas found on the corona and sulcus of the glans penis. While these represent a benign condition, psychological and cosmetic concerns often prompt patients to seek therapeutic removal of these lesions. Multiple therapeutic modalities have been reported; however, use of CO2 laser has proven to be the most effective to date. OBJECTIVE: To demonstrate the efficacy of CO2 laser in treating pearly penile papules. METHODS: Case report. RESULTS: We report the successful treatment of pearly penile papules in an African American man with CO2 laser. CONCLUSION: The use of CO2 laser is an effective treatment for pearly penile papules. J. E. Lane, MD, C. M. Peterson, MD, and J. L. Ratz, MD have indicated no significant interest with commercial supporters.  相似文献   
65.
66.
67.
Delayed graft function (DGF) in cadaver kidney transplants is a common problem and is often due to acute tubular necrosis (ATN). DGF in transplants may have a deleterious effect on long-term graft survival. Since thyroid hormone has been shown to hasten recovery from ATN in experimental models, we designed a trial to determine if a defined course of triiodothyronine (T3) would improve the short- or long-term outcome of patients with DGF in cadaveric transplants. A prospective, randomized, placebo controlled, double blind trial of T3 was carried out in patients with DGF in cadaveric renal transplants. End-points were percentage requiring dialysis, percentage recovering function, time to recovery and length of hospital stay. Long-term outcomes were percentage grafts functioning at 1 year and mean serum creatinine at 1 year. Forty-four patients were randomized to receive either T3 or placebo. Three patients were dropped from each group when early biopsies disclosed that DGF was due to rejection. The groups were well matched by age, cold ischemia time of the graft, and percentage reactivity to a random panel of antigens. Baseline thyroid function studies, including T3, reverse T3 (rT3), and thyroid stimulating hormone (TSH) levels, were similar between the two groups and typical of 'euthyroid-sick syndrome'. T3 had no effect on percentage requiring dialysis, time to recovery, percentage recovering function, or length of stay. At 1 year follow-up, graft function was similar in both groups and significantly lower than that seen in patients with good initial function. Thyroid hormone, given early in the course of DGF in cadaver kidney recipients, had no effect on the course of DGF. Long-term graft function is impaired in patients who experience post-transplant DGF compared to those who have good initial function.  相似文献   
68.
69.
Microvascular thrombosis is a prominent feature in cardiac delayed xenograft rejection (DXR). We investigated the impact of warfarin or low-molecular-weight heparin (LMWH) anti-coagulation on xenograft function using a heterotopic pig-to-primate model. Donor hearts were from CD46 transgenic pigs and baboon immunosuppression included tacrolimus, sirolimus, anti-CD20 and TPC, an alpha-galactosyl-polyethylene glycol conjugate. Three groups of animals were studied. Group 1 (n = 9) was treated with warfarin, Group 2 (n = 13) with LMWH and Group 3, received no anti-coagulant drugs. The median duration of xenograft function was 20 days (range 3-62 days), 18 days (range 5-109 days) and 15 days (range 4-53 days) in Groups 1 to 3 respectively. Anti-coagulation achieved the targeted international normalized prothrombin ratio (INR) and anti-factor Xa levels consistent with effective in vivo therapy yet, no significant impact on median xenograft function was observed. At rejection, a similar histology of thrombosis and ischemia was apparent in each group and the levels of fibrin deposition and platelet thrombi in rejected tissue was the same. Anti-coagulation with warfarin or LMWH did not have a significant impact on the onset of DXR and microvascular thrombosis. However, a role for specific anti-coagulant strategies to achieve long-term xenograft function cannot be excluded.  相似文献   
70.
Encapsulation of proteins in poly(lactide-co-glycolide) microspheres via emulsion is known to cause insoluble protein aggregates. Following protein emulsification and encapsulation in PLGA microspheres, we used circular dichroism to show that the recoverable soluble protein fraction also suffers subtle conformational changes. For a panel of proteins selected on the basis of molecular size and structural class, conformational stability measured by chemical denaturation was not indicative of stability during emulsion-encapsulation. Partial loss of structure was observed for alpha-helical proteins released from freeze-dried microspheres in aqueous buffer, with dramatic loss of structure for a beta-sandwich protein. The addition of sucrose (a lyoprotectant) did not prevent the loss of protein conformation upon encapsulation. Therefore, the conformational changes seen for the released soluble protein fraction originates during emulsification rather than microsphere freeze-drying. Analysis of the burst release for all proteins in buffer containing denaturant or surfactant showed that the degree of protein solubilisation was the dominant factor in determining the initial rate and extent of release. Our data for protein release into increasing concentrations of denaturing buffer suggest that the emulsion-denatured protein fraction remains insoluble; this fraction may represent the protein loss encountered upon comparison of protein encapsulated versus protein released.  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