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   2538篇
  免费   446篇
  国内免费   12篇
耳鼻咽喉   11篇
儿科学   89篇
妇产科学   73篇
基础医学   553篇
口腔科学   58篇
临床医学   352篇
内科学   721篇
皮肤病学   26篇
神经病学   190篇
特种医学   172篇
外科学   220篇
综合类   40篇
一般理论   1篇
预防医学   141篇
眼科学   130篇
药学   121篇
中国医学   2篇
肿瘤学   96篇
  2019年   30篇
  2015年   31篇
  2013年   74篇
  2012年   82篇
  2011年   85篇
  2010年   55篇
  2009年   63篇
  2008年   80篇
  2007年   86篇
  2006年   85篇
  2005年   95篇
  2004年   83篇
  2003年   70篇
  2002年   79篇
  2001年   65篇
  2000年   52篇
  1999年   53篇
  1998年   36篇
  1997年   60篇
  1996年   58篇
  1995年   42篇
  1994年   53篇
  1993年   40篇
  1992年   60篇
  1991年   58篇
  1990年   77篇
  1989年   74篇
  1988年   60篇
  1987年   59篇
  1986年   62篇
  1985年   50篇
  1984年   38篇
  1983年   46篇
  1982年   55篇
  1981年   56篇
  1980年   50篇
  1979年   70篇
  1978年   50篇
  1977年   41篇
  1976年   44篇
  1975年   28篇
  1974年   59篇
  1973年   47篇
  1972年   43篇
  1971年   47篇
  1970年   48篇
  1969年   43篇
  1968年   35篇
  1967年   29篇
  1966年   26篇
排序方式: 共有2996条查询结果,搜索用时 15 毫秒
31.
The effect of thymectomy at different ages in C3H mice on development of circulating leukocytes and cells of marrow, spleen and lymph nodes has been analyzed. Regardless of the age at which thymectomy is performed depression of numbers of circulating lymphocytes is produced. Thymectomy at birth did not affect significantly the relative number of lymphocytes in the marrow during the first few weeks of life, later they fell to low levels. Thymectomy at four weeks was followed by prompt reduction in relative numbers of lymphocytes in the marrow. After reaching six weeks of age, neonatally thymectomized mice showed a high proportion of monocytes in the marrow. Neonatal thymectomy and thymectomy at two weeks of age reduced the number of eosinophils in the marrow. Neonatal thymectomy inhibited development of lymphocytes in the spleen, whereas thymectomy later in life produced only transient depression of lymphocytes in this organ. In addition, neontal thymectomy decreased the relative numbers of small lymphocytes in the lymph nodes. This was associated with drastic depletion of lymphocytes in the deep cortical regions of the nodes.  相似文献   
32.
After growth and experimental conditions were established, the mycolic acid cleavage products, constituent fatty acids, and alcohols of representative strains of Mycobacterium tuberculosis, M. smegmatis, M. fortuitum complex, M. kansasii, M. gordonae, and M. avium complex were determined by capillary gas chromatography. Reproducible cleavage of mycolic acid methyl esters to tetracosanoic (24:0) or hexacosanoic (26:0) acid methyl esters was achieved by heating the sample in a high-temperature muffle furnace. The major constituent fatty acids in all species were hexadecanoic (16:0) and octadecenoic (18:1 omega 9-c, oleic) acids. With the exception of M. gordonae, 10-methyloctadecanoic acid was found in all species; moreover, M. gordonae was the only species tested which contained 2-methyltetradecanoic acid. M. kansasii was characterized by the presence of 2,4-dimethyltetradecanoic acid, M. avium complex by 2-eicosanol, and M. tuberculosis by 26:0 mycolic acid cleavage product. The mycolic acid cleavage product in the other five species tested was 24:0. Although a limited number of strains and species were tested, preliminary results indicate that this gas chromatographic method can be used to characterize mycobacterial cultures by their mycolic acid cleavage products and constituent fatty acid and alcohol content.  相似文献   
33.
34.
35.
36.
Lymphoid cells infiltrating metastatic melanomas were grown directly from cell suspensions of tumour tissue by the addition of T cell growth factor. Lymphoid cells grew out at the expense of tumour cells in six of seven freshly excised tumours, and cells from two cultures were expanded for in vitro testing of cytolytic function against different target cells. Early in culture the tumour derived lymphocytes killed fresh autologous melanoma cells and, particularly later in culture, were highly and non-specifically cytolytic for cultured melanoma and non-melanoma cells. Cultured peripheral blood lymphocytes from patients with melanoma, and from normal subjects, were cytolytic to the same degree as tumour derived lymphocytes, and also resembled cells grown from tumour tissue in possessing acid phosphatase activity which was resistant to tartrate. Cultured lymphoblasts from both tumour and peripheral blood had a T cell phenotype when analysed with monoclonal antibodies. An in vitro co-culture system was employed to study the kinetics and the precursors of these non-specific killer cells among blood mononuclear cells. Blood mononuclear cells cultured with irradiated B lymphoblasts led to the generation of non-specific cytolytic cells, referred to as activated lymphocyte killer (ALK) cells, after 7-10 days of culture and the progenitors of these ALK cells were demonstrated to be distinct from those of specific cytolytic T cells.  相似文献   
37.
The transperineal percutaneous template permanent iodine interstitial brachytherapy under "C-arm" fluoroscopic guidance is a simple, easily-learned, accurate and rapid procedure which can be performed without subjecting the patient to celiotomy. We have treated 58 patients by the transperineal percutaneous permanent interstitial brachytherapy. The use of transperineal percutaneous technique with C-arm fluoroscopic guidance improves the symmetry and dosimetry of the implant. This results in reduction of the incidence of chronic radiation-induced complications. In the group of 22 patients who underwent brachytherapy without celiotomy and lymphadenectomy and without adjuvant external-beam radiotherapy, there were no major complications.  相似文献   
38.
Zusammenfassung Die Aktion «Gesunde Ernährung» in der Gemeinde-wurde vom Gesundheitsdepartement des Kanton St. Gallen unter der Leitung des kantonalen Präventivmediziners gemeinsam mit den interessierten Gemeinden geplant, koordiniert und durchgeführt.Im Zentrum der Aktion standen gemeindeeigene, individuell gestaltete Aktivitäten von Vereinen, Schulen und des lokalen Gewerbes. Das Gesundheitsdepartement ergänzte die Aktion mit einer Wanderausstellung über Ernährungsfragen, begleitet von einer Ernährungsberaterin. Der Aufbau der Ausstellung erfolgte nach den 10 goldenen Regeln der gesunden Ernährung.Diese Aktion stellt ein konkretes Beispiel der Arbeitsteilung zwischen Kanton und Gemeinde in der Gesundheitsvorsorge dar. Das Beispiel dieser einmaligen Aktion soll Behörden, Vereinen und Einzelpersonen Wege und Methoden aufzeigen, Anliegen der Gesundheitsvorsorge auf längerfristiger Basis in der Gemeinde zu planen.
Healthy Nutrition an experience of health promotion in the county of St. Gall
Summary The drive Healthy Nutrition in communities was planned, co-ordinated und carried out as a joint action by the Health Department of the County of St. Gall, and 37 communities interested in the idea. The drive centred around the activities of the community itself, individuals, clubs, schools and local industry.The County Health Department supplemented the activity with a travelling exhibition about nutrition problems, attended by an advisor to answer questions. The build-up of the exhibition followed the 10 Golden Rules of sound nutrition.This drive was an excellent example of how health-promotion programms can be shared by county und community.This unique action should set an example to other authorities, clubs, and individuals, and show the ways and means needed to provide long-term planning for health promotion in the community.

«Alimentation saine»: le programme du canton de St-Gall
Résumé Un programme «Alimentation saine» a été planifié, coordonné et réalisé en étroite collaboration entre le Service cantonal de médecine préventive et les communes intéressées.Les activités développées par les sociétés locales, les écoles et les commerÇants ont été les éléments essentiels du programme. Le canton a, quant à lui, engagé une diététicienne et mis un bus à disposition ce qui a permis d'organiser une exposition itinérante conÇue selon les 10 règles d'or de l'alimentation saine.Ce programme est une expérience de collaboration entre le canton et les communes pour la promotion de la santé. Il devrait servir d'exemple aux autorités, sociétés locales et individus qui désirent répondre au défi de la promotion de la santé.
  相似文献   
39.
Normal erythrocyte sedimentation rate in the elderly   总被引:1,自引:0,他引:1  
Two hundred subjects aged 60-89 were selected for a study aimed at defining a reference range for the erythrocyte sedimentation rate in the elderly. The study extended a previous survey in subjects aged 20-65. The results confirmed that the sedimentation rate increases with age and that women have higher values than men but suggested that over half of elderly patients with disease would have rates within the previously defined "normal" range. It is therefore suggested that an erythrocyte sedimentation rate exceeding 19 mm in the first hour in elderly men and 22 mm in the first hour in elderly women warrants investigation.  相似文献   
40.
Objective: Chlamydia trachomatis infections are common in pregnant adolescents. Previous studies have shown that treating pregnant women of all ages with erythromycin prevents transmission of this infection to their infants. However, there are no published studies on the efficacy of aggressive screening and treatment of C. trachomatis in pregnant adolescents. This study was undertaken to determine if aggressive screening for C. trachomatis in pregnant adolescents and early treatment with erythromycin can prevent complications in their newborn infants.Methods: A group of pregnant adolescents enrolled at Teen Pregnancy Service of Milwaukee was evaluated prospectively for the presence of C. trachomatis infection. Screening was performed during the 1st and 3rd trimesters by enzyme immunoassay. Adolescents with positive enzyme immunoassays for Chlamydia were treated with erythromycin for 10 days. Those with negative enzyme immunoassays were enrolled as controls. All infants born to adolescents in both groups were followed for episodes of conjunctivitis, pneumonia, and wheezing during their 1st year of life.Results: Ninety mother/infant pairs were followed during the study period. Twenty-eight mothers (31%) had positive enzyme assay tests and all received erythromycin therapy. Nasopharyngeal cultures were obtained from 60 (67%) infants; all were negative. There were no significant differences in general characteristics, development of conjunctivitis (relative risk 1.27), wheezing (relative risk 0.91), or pneumonia (relative risk 1.12) between infants born to adolescents in either group.Conclusions: We conclude that aggressive screening and treatment of C. trachomatis infection in pregnant adolescents may prevent complications in their offspring.  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