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   1250541篇
  免费   79078篇
  国内免费   1737篇
耳鼻咽喉   17962篇
儿科学   41093篇
妇产科学   32855篇
基础医学   177371篇
口腔科学   35313篇
临床医学   108733篇
内科学   235922篇
皮肤病学   29212篇
神经病学   97381篇
特种医学   51056篇
外国民族医学   224篇
外科学   192162篇
综合类   23037篇
现状与发展   1篇
一般理论   321篇
预防医学   83711篇
眼科学   29041篇
药学   98374篇
  7篇
中国医学   3271篇
肿瘤学   74309篇
  2021年   9400篇
  2019年   9587篇
  2018年   14910篇
  2017年   11781篇
  2016年   13762篇
  2015年   15147篇
  2014年   19465篇
  2013年   28416篇
  2012年   40210篇
  2011年   42201篇
  2010年   24309篇
  2009年   21835篇
  2008年   39170篇
  2007年   42264篇
  2006年   42688篇
  2005年   41386篇
  2004年   39634篇
  2003年   38183篇
  2002年   36756篇
  2001年   65298篇
  2000年   66592篇
  1999年   55321篇
  1998年   13836篇
  1997年   12184篇
  1996年   11916篇
  1995年   11058篇
  1994年   9998篇
  1993年   9470篇
  1992年   39625篇
  1991年   38040篇
  1990年   37478篇
  1989年   35919篇
  1988年   32281篇
  1987年   31409篇
  1986年   29528篇
  1985年   27686篇
  1984年   20163篇
  1983年   16914篇
  1982年   9401篇
  1979年   18060篇
  1978年   12188篇
  1977年   10859篇
  1976年   9434篇
  1975年   10842篇
  1974年   12472篇
  1973年   12043篇
  1972年   11534篇
  1971年   10831篇
  1970年   9924篇
  1969年   9572篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
The increased number of lymphocytes in airways during an asthmatic response is believed to be the result of increased recruitment of these cells. However, it is possible that a decreased apoptotic rate could also contribute to the increased number. The aim of the present study was to investigate whether allergen airway provocation influences the apoptotic phenotype of lung and peripheral blood lymphocytes (PBL) in subjects with atopic asthma. Bronchoalveolar lavage (BAL) lymphocytes and PBL from 12 asthmatic subjects previously challenged with allergen (n = 7) or saline (n = 5) were exposed to the apoptotic stimulus tributyltin (TBT) in vitro and assayed for apoptosis. Airway allergen provocation resulted in decreased sensitivity of BAL lymphocytes to TBT-induced apoptosis, with 42.2% (range 33.9-62.5%) apoptotic cells before challenge versus 23.5% (range 15.3-42.4%) after challenge, while PBL were unaffected. The increased apoptosis resistance correlated with higher numbers of Bcl-2-expressing lymphocytes. Interestingly, baseline caspase-3-like activity was significantly elevated in viable BAL lymphocytes compared with viable PBL, and was unaltered by allergen exposure. In conclusion, allergen inhalation renders bronchoalveolar lavage lymphocytes more resistant to apoptosis while peripheral blood lymphocytes were not influenced at all, indicating that the apoptotic phenotype of airway lymphocytes may play a role in asthmatic inflammation.  相似文献   
62.
The clinical outcome and appropriate management for patients showing 'borderline changes' on allograft biopsy after renal transplantation is still controversial. In an attempt to identify predictive factors of clinical outcome of patients with such lesions, we reviewed the clinical course of 91 patients with borderline changes. Multivariate analysis revealed significant and independent effects of histological stage (i + t < or = or > 2) and time to borderline changes (< or = or > 3 months after transplant) on serum creatinine levels at 1 year from borderline changes episodes (respectively, p = 0.04 and p = 0.02) and only a significant effect of time to borderline changes on serum creatinine levels at 2 years (p = 0.005). Renal function at 1 year and 2 years as 5- and 8-year graft survival were not significantly different in the group of patients treated with antirejection therapy (T group, n = 49) compared with the untreated group (UT group, n = 42). This study strongly suggests that borderline changes with histological score (i + t) > 2 and late episodes of borderline changes should be considered to be of poor prognosis.  相似文献   
63.
In floating hip injuries, the priority of the steps in fixation has not been well described. We have treated these patients in accordance with the following protocols. In patients with pelvic ring fractures, the external fixation should be performed first, and in patients with acetabular fractures, the femoral fractures should be internally fixated first. The purpose of the present study was to review our experience with these fracture treatments to evaluate our strategy. For 8 years, 31 patients with femoral fractures associated with ipsilateral fractures: 26 unstable pelvic ring fractures and 7 unstable acetabular fractures were surgically treated at our level 1 trauma center. We reviewed the admission, operation, and follow-up records retrospectively and evaluated the order of the fixation and the complications. Two patients with acetabular fractures failed to follow our protocol outlined at the preoperative planning stage. There were no surgical difficulties other than two patients with the hemipelvis dislocated proximally who required traction of the fixated femur. The complications that were thought to be related to our protocol were one fat embolism syndrome and one pubic fracture displacement. One heterotopic ossification seemed to occur due to using a single approach for both fractures. We believe our protocol to be generally effective, however, in patients with acetabular and vertical shear type pelvic ring fractures, the internal or external fixation of the femur should be performed before the internal fixation of the pelvis.  相似文献   
64.
I discuss various viewpoints of physically disabled and nondisabled persons. I then question which views to preserve and which need to be changed as regards the subject of supervision of the physically disabled. I believe that illness and/or being physically disabled require different definitions and that for many physically disabled persons there is no either-or. In various theories it is asked how the physically disabled can be supported in their personal development, when it is maintained held that both disabled and non-disabled persons have the same mental and emotional conditions and requirements. The following theories will be considered: role theory, labeling theory, which holds to the idea of "self-fulfilling prophesy", the concept of the five pillars of identity, the expectations of self-effectiveness and of results and the theory of internal locus of control. It is a question of whether the physically disabled, like the nondisabled, should take the responsibility for their personal development upon themselves. In closing, I discuss where supervision can have a supportive effect in helping the physically disabled achieve greater personal development. Personal development improves the quality of life. Supervision for those who work with the physically disabled should contribute to reaching these goals.  相似文献   
65.
66.
67.
68.
69.
Carbon monoxide (CO), a byproduct of heme catalysis, was shown to have potent cytoprotective and anti-inflammatory effects. In vivo recipient CO inhalation at low concentrations prevented ischemia/reperfusion (I/R) injury associated with small intestinal transplantation (SITx). This study examined whether ex vivo delivery of CO in University of Wisconsin (UW) solution could ameliorate intestinal I/R injury. Orthotopic syngenic SITx was performed in Lewis rats after 6 h cold preservation in control UW or UW that was bubbled with CO gas (0.1-5%) (CO-UW). Recipient survival with intestinal grafts preserved in 5%, but not 0.1%, CO-UW improved to 86.7% (13/15) from 53% (9/17) with control UW. At 3 h after SITx, grafts stored in 5% CO-UW showed improved intestinal barrier function, less mucosal denudation and reduced inflammatory mediator upregulation compared to those in control UW. Preservation in CO-UW associated with reduced vascular resistance (end preservation), increased graft cyclic guanosine monophosphate levels (1 h), and improved graft blood flow (1 h). Protective effects of CO-UW were reversed by ODQ, an inhibitor of soluble guanylyl cyclase. In vitro culture experiment also showed better preservation of vascular endothelial cells with CO-UW. The study suggests that ex vivo CO delivery into UW solution would be a simple and innovative therapeutic strategy to prevent transplant-induced I/R injury.  相似文献   
70.
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