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   2279篇
  免费   118篇
  国内免费   75篇
耳鼻咽喉   2篇
儿科学   185篇
妇产科学   26篇
基础医学   240篇
口腔科学   58篇
临床医学   276篇
内科学   576篇
皮肤病学   73篇
神经病学   65篇
特种医学   396篇
外科学   166篇
综合类   43篇
预防医学   124篇
眼科学   19篇
药学   113篇
  2篇
肿瘤学   108篇
  2023年   6篇
  2021年   14篇
  2020年   17篇
  2019年   19篇
  2018年   33篇
  2017年   31篇
  2016年   26篇
  2015年   43篇
  2014年   50篇
  2013年   71篇
  2012年   47篇
  2011年   49篇
  2010年   92篇
  2009年   92篇
  2008年   62篇
  2007年   103篇
  2006年   65篇
  2005年   72篇
  2004年   50篇
  2003年   33篇
  2002年   50篇
  2001年   50篇
  2000年   42篇
  1999年   32篇
  1998年   128篇
  1997年   160篇
  1996年   133篇
  1995年   109篇
  1994年   119篇
  1993年   99篇
  1992年   34篇
  1991年   40篇
  1990年   36篇
  1989年   56篇
  1988年   46篇
  1987年   42篇
  1986年   50篇
  1985年   45篇
  1984年   27篇
  1983年   17篇
  1982年   25篇
  1981年   30篇
  1980年   25篇
  1979年   5篇
  1978年   8篇
  1977年   19篇
  1976年   25篇
  1975年   16篇
  1973年   4篇
  1971年   6篇
排序方式: 共有2472条查询结果,搜索用时 171 毫秒
11.
12.
BACKGROUND: To verify the criteria for human T-lymphotropic virus (HTLV) seropositivity in Western blot (WB) proposed by the Retrovirus Study Group of the French Society of Blood Transfusion, 186 blood donations that were repeatedly reactive in HTLV enzyme-linked immunosorbent assay, selected according to their WB pattern, were tested by polymerase chain reaction (PCR) and radioimmunoprecipitation assay (RIPA). STUDY DESIGN AND METHODS: In two commercially available WBs, 12 samples were confirmed as positive (rgp21+p19+p24) and 174 were interpreted as indeterminate (one or two reactivities to these proteins). The primer pairs used for the PCR allowed the amplification of type I (HTLV-I) or type II (HTLV-II) (or both) sequences. The RIPA was performed with two 35S-labeled cell lines: HTLV-I infected HUT 102/B2 and HTLV-II-infected MoT. RESULTS: Of the 12 positive samples, 11 were classified as HTLV-I-positive and one as HTLV-II-positive. Among the 174 indeterminate samples, three (WB pattern: rgp21+, p19+, p24-) were HTLV-I positive in PCR (one of them was positive in RIPA also); the other 171 were HTLV negative. CONCLUSION: In the study of a population in which 97 percent of HTLV infections are due to HTLV-I, these data support the three-protein criteria (rgp21, p19, and p24) for a positive blot reading. No HTLV infection was observed when rgp21 did not react. Consequently, p19 and/or p24 band patterns represent false reactivity and do not require PCR or RIPA confirmation. To discriminate between false- and true-positive results in the absence of MTA-1 or K55 reactivity, PCR and/or RIPA is required only when rgp21 reactivity is associated with one gag band (p19 or p24).  相似文献   
13.
The use of eye-patches allows to modulate the visual information treating process. Twelve subjects with a left unilateral spatial neglect, randomly divided into three groups — non treated, treated by right eye complete patching, treated by right hemifield patching — were assessed at 1 month and 3 months after acute episode, by means of functional and neuropsychological tests. Results in the subjects treated by complete eye-patch [5]show an improvement of all the assessment parameters whatever the unilateral spatial neglect seriousness degree may be. The progression is less convincing in the patients treated by eye-patch in right hemifield. The effects of the different modalities of occultation interpreted on the basis of anatomo-physiological and psychophysiological patterns of attention, suggest the role of ocular occultation in the initial, voluntary and directed, coven attention recovery and secondary of the automatic and divided overt attention.  相似文献   
14.
BACKGROUND: Before 1987, fewer than 50 patients per year at the authors' laboratory had a positive antibody detection test due to antepartum Rhesus immunoprophylaxis. However, after 1987, a marked increase was observed in the number of patients who had received Rh immune globulin (RhIG) during pregnancy as part of routine antepartum Rh immunoprophylaxis. In anticipation that an increased use of RhIG during pregnancy would increase the number of patients in whom anti-D was detected by this laboratory, a protocol was developed to abbreviate the process required to identify anti-D. Although this protocol was adopted primarily to address an anticipated increase in antenatal RhIG usage in women, it was also applied to alloimmunized Rh-negative males. STUDY DESIGN AND METHODS: When an Rh-negative patient (male or female) had a reactive screening test for unexpected antibodies and met certain other criteria, the patient's serum was tested with a three-vial set of Rh-negative reagent red cells (Rh-negative screening RBCs), instead of with panels of typed RBCs (panel RBCs), for the identification of anti- D or the detection of non-D antibodies. If the serum under test did not agglutinate or hemolyze Rh-negative screening RBCs, anti-D was identified and no further testing was performed. If the serum agglutinated or hemolyzed Rh-negative screening RBCs, conventional testing with panel RBCs was done to determine the antibody specificity. RESULTS: Rh-negative patients (n = 1174) who had reactive screening tests for unexpected antibodies were tested with Rh-negative screening RBCs; 1079 were found to have anti-D as a single antibody. Seven of these patients subsequently developed a non-D alloantibody, after transfusion or pregnancy, and one patient had anti-C that escaped detection at the time of initial testing with Rh-negative RBCs (a false- negative result). Ninety-two patients had anti-D in combination with a non-D antibody, and three patients had a non-D antibody but not anti-D. Use of the anti-D identification protocol actually reduced the laboratory workload by 176 College of American Pathologists workload units per month, in spite of a marked increase in the number of patients in whom anti-D was detected. No hemolytic transfusion reaction was attributed to the abbreviation of anti-D identification. CONCLUSION: The identification of anti-D may be abbreviated without jeopardizing patient safety. Such a protocol can reduce laboratory workload and might be particularly appealing to health care facilities that perform antibody detection testing on large numbers of Rh-negative pregnant women, especially if antepartum RhIG is administered routinely.  相似文献   
15.
Isolated headache as the presenting clinical manifestation of intracranial tumors: a prospective study. Cephalalgia 1994;1'4:270-1. Oslo. ISSN 0333-1024We prospectively studied over two years the incidence of headache as the initial and isolated clinical manifestation of adult patients suffering from intracranial tumors ( n = 183). Fifteen patients (8%) exhibited headache as their first and isolated clinical manifestation. Age, sex, neoplasm localization, or pathological diagnosis did not correlate with the presence of headache. Posterior fossa location and hydrocephalus, though not reaching statistical significance, were more frequent in patients who presented with headache as the first symptom. At the moment of diagnosis, 59 (31%) of the patients admitted to headache, though only I out of the 15 patients starting as headache still had this symptom as the only manifestation. From our experience in adults, isolated headache for longer than 10 weeks will only exceptionally be secondary to an intracranial neoplasm.  相似文献   
16.
17.
尼莫地平对烫伤大鼠脑内ZO-1 mRNA及血脑屏障通透性的影响   总被引:2,自引:0,他引:2  
目的:观察尼莫地平对严重烫伤大鼠脑内紧密连接相关蛋白ZO-1mRNA及血脑屏障通透性的影响。方法:实验于2005-04/10在南昌大学基础医学院应用解剖实验室完成。①取健康SD大鼠132只分为正常对照组12只、烫伤组60只,尼莫地平组60只,后两组又设烫伤后1,3,6,12,24h5个时间点,每个时间点12只,其中6只用于脑组织伊文思蓝含量的测定,剩余6只用于ZO-1mRNA的检测。②烫伤组和尼莫地平组大鼠100℃开水烫伤15s,造成背部30%体表总面积Ⅲ度烧伤。尼莫地平组大鼠于烫伤后即刻腹腔注射尼莫地平(0.5mg/kg),其他2组不给药。③各组大鼠于相应的时间点麻醉并处死动物取材,应用化学定量方法检测大鼠脑组织内伊文思蓝含量,运用RT-PCR方法检测大鼠脑内ZO-1mRNA的表达变化。结果:经补充后132只大鼠进入结果分析。①大脑伊文思蓝含量:正常对照组为(10.18±1.79)μg/g,烫伤组伤后1,3,6,12h均高于正常对照组(P<0.05),其高峰在烫伤后6h,为(20.00±0.58)μg/g;尼莫地平组伤后1,6,12h均低于烫伤组(P<0.01),烫伤后6h时为(16.74±0.78)μg/g。②小脑伊文思蓝含量:正常对照组为(12.90±1.32)μg/g,烫伤组伤后1,3,6,12h均高于正常对照组(P<0.05),其高峰在烫伤后6h,为(31.3±1.47)μg/g;尼莫地平组伤后1,3,6,12h均低于烫伤组(P<0.01),烫伤后6h时为(21.05±2.36)μg/g。③脑组织ZO-1mRNA的表达:烫伤组烫伤后3,6,12,24h分别为正常对照组的(0.1235±0.0158),(0.1890±0.0531),(0.2014±0.0412),(0.1555±0.0163)倍(P<0.01);尼莫地平组较烫伤组高,以烫伤后3,6h最为明显,分别为烫伤组的3.96及1.81倍(P<0.01).结论:①严重烫伤后血脑屏障通透性增高,脑内ZO-1mRNA表达下降。②烫伤后早期应用尼莫地平能防止脑内ZO-1mRNA表达下降,并能起到保护血脑屏障功能的作用。  相似文献   
18.
BACKGROUND: The storage of platelet concentrates (PCs) induces a reduction in the platelet surface expression of glycoprotein (GP) Ib alpha. The location of the platelets' high-affinity binding site for thrombin has been postulated as being located on GPIb alpha. This study attempts to determine whether loss or alteration of GPIb alpha during storage of PCs is related to impairment in the reactivity of platelets to thrombin. STUDY DESIGN AND METHODS: In this study, platelet surface expression of GPIb alpha was monitored by means of flow cytometry, throughout standard storage of PCs for up to 10 days. Two thrombin- induced platelet responses, the binding of radiolabeled fibrinogen and the platelet surface expression of P-selectin, were evaluated. Thrombin- binding assays were also performed to assess the number of thrombin receptors in platelets. RESULTS: The surface expression of the GPIb/IX complex declines during storage of PCs. The thrombin-induced maximal binding of fibrinogen in platelets stored for 3, 7, and 10 days was 77 +/? 7 percent, 60 +/? 20 percent, and 34 +/? 25 percent, respectively, of that found in fresh platelets. Moreover, the concentration of thrombin needed for 50 percent of platelets to express the CD62 antigen P-selectin at the surface increased from 0.05 U per mL in fresh platelets to 0.11, 0.56, and 1.2 U per mL in platelets stored for 3, 7, and 10 days, respectively. Thrombin-binding experiments demonstrated a significant reduction in the number of high-affinity binding sites throughout storage of PCs (55 +/? 21 sites/platelet in 10-day-stored platelets vs. 73 +/? 25 in fresh platelets). A significant correlation was also observed between the number of high-affinity thrombin-binding sites and surface expression of GPIb alpha. Selective blockage of the thrombin-binding site on GPIb alpha with monoclonal antibody LJ-Ib10 also inhibited the response of fresh platelets to thrombin, up to a level equivalent to that found in 3-day-stored platelets. CONCLUSION: The loss of the GPIb alpha-located high-affinity thrombin-binding site may impair the ability of platelets to become activated by thrombin as storage time increases.  相似文献   
19.
Homologous blood transfusions have been associated in both animals and humans with an increased risk of acute postoperative infectious complications. Eighty-four patients who underwent hip replacement surgery and were transfused with 2 or 3 units of blood were analyzed to determine whether those receiving homologous transfusions had different outcomes than those receiving autologous blood only. Only patients free of other risks for postoperative infection were studied. Those receiving homologous blood had a 32 percent (16/50) rate of proven or suspected infections, which was significantly higher than the 3 percent (1/34) rate in patients receiving autologous blood (p = 0.0029). Wound infections accounted for only a minority (6/17) of the proven or suspected infections, which suggests that nonsurgical factors contributed to these complications. The patients identified as being infected required significantly more antibiotic therapy (mean, 7.6 days) and lengthier hospital stays (mean, 15.5 days) than the patients who remained free of evidence of infection (means: 2.3 days of antibiotics and 12.3 days in the hospital) (p = 0.0001 for each variable). Other potential risk factors for infection, such as duration of surgical procedure, advanced patient age, amount of blood loss, type of anesthesia, surgeon performing the operation, use of a cemented versus porous-coat prosthesis, leukocytopenia, anemia, and underlying medical diagnosis, did not account for the differences in infection rates seen in those receiving homologous and autologous transfusions. These results confirm previous reports of an increased risk of postoperative infection in patients receiving homologous transfusions. Homologous transfusion may contribute to an increased risk of infection by immunologic modulation of the recipient.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
20.
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