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   761篇
  免费   49篇
  国内免费   13篇
耳鼻咽喉   1篇
儿科学   97篇
妇产科学   2篇
基础医学   47篇
口腔科学   17篇
临床医学   77篇
内科学   116篇
皮肤病学   6篇
神经病学   12篇
特种医学   185篇
外科学   79篇
综合类   47篇
预防医学   18篇
眼科学   5篇
药学   36篇
  1篇
肿瘤学   77篇
  2022年   5篇
  2021年   9篇
  2020年   3篇
  2019年   3篇
  2018年   8篇
  2017年   7篇
  2016年   6篇
  2015年   12篇
  2014年   6篇
  2013年   8篇
  2012年   17篇
  2011年   14篇
  2010年   15篇
  2009年   12篇
  2008年   16篇
  2007年   22篇
  2006年   26篇
  2005年   19篇
  2004年   17篇
  2003年   18篇
  2002年   11篇
  2001年   24篇
  2000年   8篇
  1999年   14篇
  1998年   26篇
  1997年   24篇
  1996年   20篇
  1995年   25篇
  1994年   25篇
  1993年   36篇
  1992年   15篇
  1991年   11篇
  1990年   17篇
  1989年   24篇
  1988年   30篇
  1987年   47篇
  1986年   37篇
  1985年   30篇
  1984年   16篇
  1983年   23篇
  1982年   12篇
  1981年   19篇
  1980年   13篇
  1979年   16篇
  1978年   18篇
  1977年   9篇
  1976年   4篇
  1975年   8篇
  1974年   5篇
  1933年   2篇
排序方式: 共有823条查询结果,搜索用时 15 毫秒
71.
72.
73.
74.
BACKGROUND: JMH is a high-frequency red cell blood group antigen that resides on a 76- to 80-kDa glycosylphosphatidylinositol-linked protein also known as CDw108. Antibodies with JMH specificity are often autoimmune and are usually, if not always, clinically benign. Some individuals with JMH-variant antigen produce alloantibodies to JMH, but little evidence concerning their clinical significance is available. This article reports on two patients who express a JMH-variant antigen and produced alloanti-JMH. STUDY DESIGN AND METHODS: Murine monoclonal antibodies and human antibodies to JMH were used in hemagglutination, radioimmunoassay, and Western blot testing of red cells from two JMH- variant patients; antiserum from one of these patients was also used in biochemical studies. In addition, in vivo survival of JMH-positive red cells was studied in the same patient. RESULTS: Biochemically, both examples of red cells with the JMH-variant phenotype expressed a JMH protein with a molecular weight similar to that of the normal JMH protein. For both patients, family studies suggested an autosomal recessive pattern of inheritance. Survival study demonstrated reduced in vivo red cell survival in one patient. CONCLUSION: JMH-variant phenotypes express a protein of normal molecular weight and are inherited in an autosomal recessive pattern. Furthermore, individuals with this phenotype can produce clinically significant antibodies.  相似文献   
75.
Kidney transplants between strains of mice which are incompatible at either the K or the D end of the H-2 complex usually function for prolonged periods supporting the lives of nephrectomized recipients. This occurs with no recipient treatment. With multiple H-2 and non-H-2 determined incompatibilities, transplants may be rejected but more slowly than skin grafts. In the strain combination studied most extensively in these experiments (B10.D2 to B6AF(1)) in which the incompatibility was confined to the K end of the H-2 region, about 70 percent of recipients survived for many weeks with normal blood urea nitrogen levels. Skin grafts between untreated members of these strains were rejected promptly (mean survival time of 13.5 +/- 1.1 days) as were kidney transplants to recipients of prior skin grafts. Donor strain skin grafts to recipients of kidney transplants after kidney transplantation enjoyed greatly prolonged survival whereas skin grafts from a third party (A.SW) were rejected normally. If kidney tissue was transferred in the form of free grafts without primary vascular union, it was rejected promptly leaving its recipient highly immunized. Cellular and humoral immunity to donor antigens declined over the first few weeks after transplantation, and the spleens of long-term recipients contained no “killer cells.” Recipient lymphoid cells could mount active graft versus host reactions to donor strain antigens on transfer to neonatal mice. Nevertheless, they were distinctly less able to respond specifically by the production of killer cells to donor strain antigens after sensitization in vitro. No evidence that this defect was associated with the presence of suppressor cells was forthcoming from several types of in vivo and in vitro tests.  相似文献   
76.
目的:建立概率预测的Logistic回归模型,分析影响神经原性膀胱尿动力学的主要危险因素和保护因素,并评价模型的灵敏度、特异度和准确性。方法:收集2004-03/2006-03在中山大学附属第一医院尿流动力学室行尿动力学检查的患者80例,对其尿动力学图的客观指标进行回顾性分析。①80例中尿流动力学图正常者29例为对照组,尿流动力学图显示神经原性膀胱者51例为病例组。②将两组资料采用统一的变量指标(包括性别、年龄以及尿流动力学仪器自动采集计算的34个数据)输入SPSS12.0版本数据库,进行主成分分析,将贡献率高的主成分进行单因素分析,取其中有统计学意义的主成分作多因素Logistic回归分析,建立Logistic回归方程,计算各因素的OR值,并计算模型的灵敏度、特异度和准确度。结果:①尿动力学34个客观指标进行主成分分析后得出8个主成分(C1~8),取贡献率高的5个主成分进行单因素分析,结果有2个主成分可以进入多因素Logistic回归分析。获得Logistic回归概率预测模型,此概率预测模型灵敏度为82.4%,特异度75.9%,准确度为80.0%。②主成分C1的OR值=4.606,C1中的首次尿意膀胱压力和逼尿肌压力、正常尿意膀胱压力和逼尿肌压力、强烈尿意膀胱压力和逼尿肌压力、尿急尿意膀胱压力和逼尿肌压力、充盈期最大逼尿肌压力的系数分别是0.823,0.834,0.781,0.913,0.924,0.932,0.883,0.916,0.857,高于C1中其他变量的系数,故可把主成分C1看作是一个“压力型”指标。③C3的OR值=0.183,C3中系数较高的变量是最大流率、平均流率、压力流率中最大流率和平均流率,分别是0.694,0.777,0.768,0.771,因此把C3看作为“流率”变量指标。结论:①成功构建了人神经原性膀胱尿流动力学图的概率预测模型,其中“压力”因子主成分是危险因素,“流率”因子主成分是保护因素。②概率预测模型的灵敏度、特异度和准确性显示其有较好的代表性。  相似文献   
77.
Ultraviolet-B (UV-B) irradiation of platelet concentrates (PCs) may prevent the development of posttransfusion HLA alloimmunization. This study evaluated the effect of increasing doses of UV-B radiation on stored PCs. Pooled PCs were irradiated at UV-B doses of 600, 2400 or 10,000 mJ per cm2 and stored up to 96 hours under standard blood bank conditions. Compared to nonirradiated room-temperature and 37 degrees C controls, the irradiated units showed no significant changes in platelet count, white cell count, discharge of lactate dehydrogenase, release of beta-thromboglobulin, metabolism of ATP, ADP, ammonia, glutamine, glutamate, hypoxanthine, pCO2, or pO2 at any time of storage following any of the three UV-B doses. However, after a dose of 10,000 mJ per cm2, there were significant decreases in in vitro assays of platelet function-specifically, osmotic recovery and morphology score. Some metabolic systems were also affected by the 10,000 mJ per cm2 radiation dose, as shown by a decline in pH and bicarbonate and an increase in glucose consumption and lactate production (p < 0.05). The changes in these latter assays appeared only after 96 hours of postirradiation storage. Such changes were not seen in either the room- temperature or 37 degrees C control groups. Thus, heat generated during irradiation, per se, did not appear responsible for the observed in vitro changes in platelet function and metabolism. On the basis of the assays analyzed, it is concluded that UV-B irradiation of PCs at doses up to 10,000 mJ per cm2 does not induce significant metabolic or functional derangements following short-term storage (24-48 hours).(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
78.
A patient without evident immune deficiency who received a transfusion of blood from a second-degree family member developed fatal transfusion- associated graft-versus-host disease (TA-GVHD). The donor was homozygous for an HLA haplotype for which the recipient was heterozygous (one-way HLA match). All 39 reported cases of TA-GVHD in immunocompetent patients were reviewed to ascertain the predisposing factors and to define the indications for irradiating blood for this population. HLA typing was described in 15 cases; in 13, including seven related and six unrelated donors, a one-way HLA match was present. Thirty-one (79%) of the 39 cases were reported from Japan (and 196 other cases are cited in the Japanese literature), but a one-way HLA match among unrelated donors at HLA-A, -B, -DR loci is only approximately two to four times more likely in Japanese persons than in whites. Fresh blood (< 96 hours old) was used in 29 (94%) of the 31 cases reported from Japan and in 33 (87%) of 38 cases overall (in one case, the age of the blood used was not reported). Thus, factors that appear to predispose to TA-GVHD in immunocompetent patients are a one- way HLA match, fresh blood, and, possibly, Japanese ancestry. Irradiating cellular blood components from all blood relatives of transfusion recipients will not completely eliminate the risk of TA- GVHD.  相似文献   
79.
The objective of the study was to develop a clinical prediction rule (CPR) to identify patients with neck pain likely to improve with cervical traction. The study design included prospective cohort of patients with neck pain referred to physical therapy. Development of a CPR will assist clinicians in classifying patients with neck pain likely to benefit from cervical traction. Eighty patients with neck pain received a standardized examination and then completed six sessions of intermittent cervical traction and cervical strengthening exercises twice weekly for 3 weeks. Patient outcome was classified at the end of treatment, based on perceived recovery according to the global rating of change. Patients who achieved a change ≥+6 (“A great deal better” or “A very great deal better”) were classified as having a successful outcome. Univariate analyses (t tests and chi-square) were conducted on historical and physical examination items to determine potential predictors of successful outcome. Variables with a significance level of P ≤ 0.15 were retained as potential prediction variables. Sensitivity, specificity and positive and negative likelihood ratios (LRs) were then calculated for all variables with a significant relationship with the reference criterion of successful outcome. Potential predictor variables were entered into a step-wise logistic regression model to determine the most accurate set of clinical examination items for prediction of treatment success. Sixty-eight patients (38 female) were included in data analysis of which 30 had a successful outcome. A CPR with five variables was identified: (1) patient reported peripheralization with lower cervical spine (C4–7) mobility testing; (2) positive shoulder abduction test; (3) age ≥55; (4) positive upper limb tension test A; and (5) positive neck distraction test. Having at least three out of five predictors present resulted in a +LR equal to 4.81 (95% CI = 2.17–11.4), increasing the likelihood of success with cervical traction from 44 to 79.2%. If at least four out of five variables were present, the +LR was equal to 23.1 (2.5–227.9), increasing the post-test probability of having improvement with cervical traction to 94.8%. This preliminary CPR provides the ability to a priori identify patients with neck pain likely to experience a dramatic response with cervical traction and exercise. Before the rule can be implemented in routine clinical practice, future studies are necessary to validate the rule. The CPR developed in this study may improve clinical decision-making by assisting clinicians in identifying patients with neck pain likely to benefit from cervical traction and exercise. This study was approved by the Institutional Review Board at Brooke Army Medical Center, Fort Sam Houston, Texas. The opinions and assertions contained herein are the private views of the authors and are not to be construed as official as reflecting the views of the Department of the Army, Department of the Air Force, Department of the Navy, or the Department of Defense.  相似文献   
80.
Pharmaceutical Research - The quality testing and approval procedure for most pharmaceutical products is a streamlined process with standardized procedures for the determination of critical quality...  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