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   227篇
  免费   4篇
儿科学   8篇
妇产科学   3篇
基础医学   18篇
口腔科学   1篇
临床医学   18篇
内科学   40篇
皮肤病学   13篇
神经病学   3篇
特种医学   3篇
外科学   37篇
综合类   13篇
预防医学   25篇
眼科学   1篇
药学   44篇
肿瘤学   4篇
  2015年   2篇
  2013年   8篇
  2010年   4篇
  2009年   2篇
  2008年   2篇
  2007年   4篇
  2006年   2篇
  2001年   2篇
  2000年   4篇
  1999年   3篇
  1998年   3篇
  1997年   8篇
  1996年   11篇
  1995年   5篇
  1994年   8篇
  1993年   10篇
  1992年   6篇
  1991年   6篇
  1990年   4篇
  1989年   4篇
  1988年   6篇
  1987年   6篇
  1986年   4篇
  1985年   2篇
  1984年   3篇
  1983年   5篇
  1981年   3篇
  1980年   5篇
  1979年   2篇
  1978年   1篇
  1975年   2篇
  1973年   1篇
  1972年   2篇
  1971年   2篇
  1970年   1篇
  1969年   1篇
  1968年   2篇
  1965年   1篇
  1963年   4篇
  1961年   1篇
  1959年   4篇
  1958年   9篇
  1957年   15篇
  1956年   11篇
  1955年   14篇
  1954年   5篇
  1949年   8篇
  1948年   5篇
  1947年   1篇
  1946年   1篇
排序方式: 共有231条查询结果,搜索用时 15 毫秒
81.
The production and detailed immunostaining properties of a new rat monoclonal antibody (ICR.2) to epithelial membrane antigen are reported. The antibody was selected for its ability to compete with the polyclonal antiserum (M7), used in the original immunohistological studies, in order that it might serve as a direct replacement in diagnosing epithelial tumours. Most of the staining reactions on normal tissues were identical to those previously reported with M7 but there were some important differences. They included: positivity of renal and adrenal capsular fibroblasts, perineurium, some myoepithelial and smooth muscle cells, occasional osteoblasts and squamous and thyroid follicular epithelium in the normal state. The intercellular canaliculi of sweat glands and secretory canaliculi of gastric oxyntic cells were clearly demonstrated. These staining reactions could be obtained with M7 when a sensitive detection system was used although the results were usually weak and inconsistent. Nearly all adenosquamous and transitional carcinomas were positive. The remaining tumours fell into three major groups: (1) those which were consistently or nearly consistently negative--melanoma, seminoma, rhabdomyosarcoma, alveolar soft part sarcoma, adrenal cortical carcinoma, granulocytic sarcoma, paraganglioma, non-Hodgkin's lymphoma. Hodgkin's disease and embryonal carcinoma: (2) those which were either negative or positive with distinctive patterns of staining--basal cell carcinoma, embryonal tumours: and (3) non-epithelial tumours that were consistently positive--epithelioid sarcoma, synovial sarcoma, osteosarcoma, chordoma and myeloma--or positive in a significant minority of cases--leiomyosarcoma, malignant fibrous histiocytoma, clear cell sarcoma of tendon sheath, various neuroectodermal tumours.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
82.
83.
84.
The concepts of health promotion and seif care have common origins.Both represent new thinking about the roles of the professionaland lay sectors in health protection. The two concepts developedquite d however. The concept of self care did not attain thesame level of legitimacy and stability as health promotion,which has evolved from an alternative approach to the dominanceof traditional disease prevention into a rapidly developinghealth field. The emergence of the concept of self care andthe reasons for its relative lack of acceptance are dLtcussed.It is concluded that the concept of self care is logically alliedwith the field of health promotion and serves an important functionin optimiz ing health related behavior.  相似文献   
85.
We have previously shown that peritoneal macrophages from Trypanosoma brucei infected mice, but not from uninfected mice, expressed high levels of procoagulant activity that could not be produced in vitro by incubation of unstimulated macrophages with bloodstream forms of trypanosomes. In the present study we demonstrate that trypanosome-induced macrophage activation can be achieved in vitro by providing either sensitized (day 7 of infection) lymphocytes and trypanosomes or the supernatant fluid from this interaction. The ability of lymphocytes to secrete macrophage-activating lymphokines is enhanced up to day 12 of infection but was absent in the later stages. Although enhancement of the procoagulant activity occurred in infected nude mice, it seems that macrophage function in African trypanosomiasis, as regards the expression of procoagulant activity, is regulated by T-lymphocytes.  相似文献   
86.
A family is reported in which isolated hypogonadotrophic hypogonadism is inherited as an autosomal dominant condition with variable expression. In previous familial cases, inheritance was autosomal recessive. Comparison is made with the endocrine and genetic findings in Kallmann's syndrome, which should be considered a separate disorder. There is difficulty in drawing a sharp distinction between hypogonadotrophic hypogonadism and constitutional delay in puberty in this family.  相似文献   
87.
Results of Teratogenicity Testing of m-Aminophenol in Sprague-DawleyRats. RE, T. A., LOEHR, R. F., RODRIGUEZ, S. C., RODWELL, D.E., AND BURNETT, C. M. (1984). Fundam. Appl. Toxicol. 4, 98–104.meta-Aminophenol (m-AP) was administered in the diet to femaleSprague-Dawley rats for a period of at least 90 days at levelsof 0.1, 0.25, and 1.0%. In the 0.25% group a significant reductionin body weight was noted, in comparison with control values,and in the 1.0% group a significant reduction in both body weightand food consumption was noted. Ten of the rats in each groupwere necropsied. Deposition of iron positive pigment in thespleen, liver, and kidney combined with decreased red bloodcell count and hemoglobin and increased mean corpuscular volumeindicated a hemolytic effect. There were also morphologic changesin the thyroid which were consistent with hyperactivity. Theremaining 25 rats in each group were removed from m-AP treatmentand immediately mated to untreated males of the same strain.After the mating period the dams again were given m-AP for theduration of gestation. All dams were killed on Day 20 of gestation;one-third of the fetuses were examined for visceral malformationsand two-thirds for skeletal malformations and variations. Anadditional significant reduction in body weight gain was notedduring gestation in the 1.0% group as compared to the controlgroup. There were no other adverse dose-related findings demonstratedin the reproduction performance of the dams or in the survivalor development of their offspring. Therefore, although maternaltoxicity was demonstrated at the highest dose level, there wasno evidence of teratogenic or embryofetal toxicity at any doselevel tested.  相似文献   
88.
Minute ventilation (VE) controlled rate adaptive pacemakers determine the paced rate increase during exercise by measuring changes in transthoracic impedance that have been shown to correlate well with VE. To determine the normal coupling of heart rate (HR) to VE, this relationship was evaluated in 30 younger and 25 older, healthy subjects using peak cardiopulmonary exercise testing. After determining the anaerobic threshold (AT), the linear HR to VE slope was determined both below and above the AT. In addition, the entire curve of the HR to VE relationship was assessed by a "best fit" regression analysis method. The relationship of HR to VE was more often logarithmic in younger as compared to older subjects. The HR to VE slope below the AT was always steeper than above the AT in younger subjects. Females of both age subgroups demonstrated a significantly greater slope below and above the AT. For the appropriate programming of VE controlled, rate responsive pacemakers, one should take into consideration age- and sex-specific differences in the HR to VE relationship throughout exercise. Therefore, age- and sex-specific programmable features for rate responsive parameters should be incorporated into pacemakers using VE controlled rate adaptive algorithms.  相似文献   
89.
The objective of rate adaptive pacemakers that measure minute ventilation by tmnsthoracic impedance is to simulate the physiological relationship of the sensed signal to the sinus node response during exercise, thus achieving an appropriate matching of heart rate with patient effort. The purpose of this study was to determine the physiological relationship between heart rate and minute ventilation (HR/VE) during peak exercise testing in order to develop a database for appropriate rate adaptive slope programming of minute ventilation controlled pacemakers. Due to several clinical limitations of peak exercise testing, it was additionally determined whether the 35-watt “low intensity treadmill exercise” (LITE) protocol can be used as a substitute for peak exercise test using the “ramping incremental treadmill exercise” (RITE) protocol in order to assess the correct HR/VE slope below the anaerobic threshold. The stress tests were performed on a treadmill with the collection of breath-by-breath gas exchange. Linear regression analysis was used to determine the HR/VE slope below and above the anaerobic threshold and during the early, dynamic phase of low intensity exercise with the RITE and LITE protocols, respectively. The results of this testing in 41 healthy subjects demonstrated that the HR/VE relationship throughout treadmill exercise using the RITE protocol was not linear but curvilinear in nature, with a steeper HR/VE slope of 1.54 ± 0.51 below versus 1.15 ± 0.37 above the anaerobic threshold (P < 0.005). The HR/VE slope determined during the early, dynamic phase of the LITE protocol (1.58 ± 0.88) did not differ from the HR/VE slope from rest to anaerobic threshold obtained using the peak exercise RITE test (1.54 ± 0.51; P = 0.79), Rate adaptive pacing should simulate the curvilinear relationship between heart rate and minute ventilation from rest to peak exercise. The HR/VE slope determined during the early, dynamic phase of low intensity exercise represents the HR/VE slope derived from the RITE protocol below the anaerobic threshold. According to the peak exercise database, the slope above anaerobic threshold can easily be calculated as a percentage of the slope below the anaerobic threshold. The LITE protocol can, therefore, be effectively performed as a substitute for peak exercise stress tests to determine the correct pacemaker rate response factor in order to obtain a physiological heart rate to minute ventilation relationship for the appropriate matching of paced heart rate with patient effort.  相似文献   
90.
Aerobic Capacity in Rate Modulated Pacing   总被引:1,自引:0,他引:1  
Whether heart rate or AV synchrony is the most important factor for an increase in aerobic capacity was evaluated in a comparative study between sinus bradycardia, VVIR, DDD, and DDDR stimulation. Sixteen patients (mean age 67 years) with chronotropic incompetence and impJanted DDDR pacemaker (Telectronics META 1250) were randomly studied by cardiopulmonary exercise testing. All patients were exercised to their anaerobic threshold (ATJ with the following heart rates: DDD 84 ± 3, WIR 110 ± 5, and DDDR 116 ± 6 beats/min. Mean oxygen uptake (VO2, mL/kg per min) at AT was 7.4 ± 0.3 in DDD and WIR modes. A 12% increase was measured in DDDR mode (8.3 ± 0.4). Compared to VVIR work capacity in the DDDR mode was improved by 17% (41 vs 48 W/min). In patients with isolated sinus node disease (n = 9) the increase of VO2 and work capacity at AT during DDDR mode was more pronounced (16% and 20%, respectively, compared to VVIR). In patients with intermittent second or third degree AV block (n = 7) the differences between the pacing modes were not significant. This might partly be due to a lesser degree of chronotropic incompetence in this subgroup. In conclusion only the conjunction of heart rate increase and preservation of AV synchrony provides a significant improvement in aerobic capacity during exercise.  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