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   1342篇
  免费   133篇
  国内免费   13篇
耳鼻咽喉   17篇
儿科学   85篇
妇产科学   18篇
基础医学   254篇
口腔科学   22篇
临床医学   142篇
内科学   222篇
皮肤病学   23篇
神经病学   49篇
特种医学   173篇
外科学   101篇
综合类   27篇
预防医学   127篇
眼科学   8篇
药学   90篇
肿瘤学   130篇
  2022年   13篇
  2021年   16篇
  2019年   16篇
  2018年   18篇
  2017年   10篇
  2016年   13篇
  2015年   21篇
  2014年   23篇
  2013年   46篇
  2012年   41篇
  2011年   40篇
  2010年   29篇
  2009年   40篇
  2008年   21篇
  2007年   55篇
  2006年   40篇
  2005年   45篇
  2004年   26篇
  2003年   35篇
  2002年   36篇
  2001年   39篇
  2000年   27篇
  1999年   39篇
  1998年   65篇
  1997年   56篇
  1996年   38篇
  1995年   31篇
  1994年   20篇
  1993年   24篇
  1992年   21篇
  1991年   17篇
  1990年   35篇
  1989年   25篇
  1988年   32篇
  1987年   33篇
  1986年   34篇
  1985年   36篇
  1984年   30篇
  1983年   28篇
  1982年   21篇
  1981年   22篇
  1980年   21篇
  1979年   29篇
  1978年   16篇
  1977年   24篇
  1976年   15篇
  1975年   21篇
  1974年   12篇
  1973年   12篇
  1969年   11篇
排序方式: 共有1488条查询结果,搜索用时 0 毫秒
101.
Two types of splenogonadal fusion (SGF) have been proposed. In the continuous type the spleen is connected to the gonad, and often it is associated with limb defects and other anomalies such as micrognathia, microglossia, anal atresia, and hypoplastic lungs. Associated abnormalities are lower in the discontinuous type of SGF, where there is fusion between the gonad and accessory splenic tissue, without connection with the normal spleen. The cause of SGF and SGF with limb defects (SGFLD) is unknown. On the basis of associated orofacial limb abnormalities, some authors have suggested that SGFLD may be related to the Hanhart complex. Others have noted the overlap between SGFLD and femoral-facial syndrome (FFS). We consider SGFLD a developmental field defect that originates during blastogenesis. Although the cause is unknown, the earlier its action, the more severe the involvement resulting in SGFLD; later action may result only in SGF.  相似文献   
102.
PURPOSE: In circulations with pulsatile pulmonary artery flow the pulmonary venous wedge pressure (PVWp) has been validated as a good estimate of pulmonary artery pressure (PAp), when PAp is low. The purpose of this study was to validate PVWp estimates of PAp in the less-pulsatile pulmonary circulation of children after bidirectional Glenn shunts. METHODS: A retrospective study was performed of 22 simultaneous measurements of PVWp and PAp made during 20 catheterizations in 19 children who had undergone bidirectional Glenn procedures. The PAp was measured directly from the branch PA ipsilateral to the side of the PVWp, or in the SVC. Pulmonary resistance (Rp) was calculated with both PAp and PVWp, to assess the impact of PAp estimates on Rp determinations. RESULTS: Patients ranged in age from 5 months to 10.7 years. There were a variety of univentricular cardiac malformations in the study group. Two children had antegrade pulmonary blood flow in addition to a bidirectional Glenn shunt. The mean PAp ranged from 4 to 14 mmHg, while mean PVWp ranged from 3 to 15 mmHg. Mean PVWp never differed from mean PAp by more than 3 mmHg. There was a significant linear relation between mean PAp and PVWp: PAp = 0.86 (PVWp) + 2.0 (R2 = 0.89; P < 0.0001). PVWp provided a good approximation of PAp regardless of the presence (n = 2) or absence (n = 19) of antegrade pulmonary flow. There was a good linear correlation between the Rp calculated by both methods (RpPAp = 0.9 (RpVWp) + 0.5; R2 = 0.74; P < 0.0001). CONCLUSION: The mean PVWp provides a close approximation of mean PAp in children with a bidirectional Glenn shunt and provides valuable hemodynamic information in cases where direct PAp measurements are unavailable.  相似文献   
103.
OBJECTIVE: Anthropologists with an interest in American Indian alcohol use have long held that how native people drink has been conditioned by aspects of the social organization of their societies prior to the disruptive influences of European colonialism. Our goal in this article was to explicitly test the importance of these factors in four contemporary American Indian cultural groups. METHOD: Using data on adolescent alcohol use drawn from the first full wave of the longitudinal Voices of Indian Teens Project (N = 1,651, 51% female), we tested whether patterns of quantity-frequency of alcohol use and the negative consequences of alcohol use predicted by social organzational variables were found among contemporary adolescents and, subsequently, whether these differences persisted when other, more proximal, variables were included. RESULTS: Cultural differences appeared to account for a small percentage of the variance in both quantity-frequency of alcohol use and negative consequences in the initial steps of our analyses, but the pattern in these data was not consistent with the predictions of existing theories regarding aboriginal social organization. Moreover, these cultural differences were no longer significant in the final step of our analyses, suggesting that the cultural differences that did exist were better explained by other factors, at least among these adolescents. CONCLUSIONS: Although these analyses did not indicate that culture was irrelevant in understanding adolescent alcohol use in American Indian communities, classic formulations of these effects were of limited utility in understanding the experiences of contemporary American Indian adolescents.  相似文献   
104.
Neutropaenic patients are at particular risk of developing a pseudomonal fasciitis known as ecthyma gangraenosum. Despite the similarities with necrotising fasciitis, Fournier's gangrene has a very different aetiology and management.  相似文献   
105.
Interventional radiology in the spleen   总被引:2,自引:0,他引:2  
Despite the widespread use of interventional radiologic techniques, there has been reluctance to apply these to the spleen. Concern for bleeding and difficulty in negotiating around the colon and pleura have limited its use. The authors report their experience with interventional radiology of the spleen in 35 cases, including percutaneous biopsy (n = 5), diagnostic and therapeutic fluid aspiration (n = 14), and catheter drainage of abscesses (n = 9), hematomas (n = 2), intrasplenic pancreatic pseudocysts (n = 2), and necrotic tumor (n = 1). Transsplenic fluid aspiration and biopsy of the pancreas and adrenal gland were performed as well (n = 2). All procedures were performed under computed tomographic or ultrasound guidance. Biopsies were performed with 22- or 20-gauge needles only; no complications were encountered. Diagnoses included primary and secondary malignancies and an infectious process. Drainages were successful in 11 of 14 patients; pleural effusions occurred in two cases, but neither required specific therapy. Interventional radiologic procedures in the spleen are feasible, and the authors discuss methods to promote their safe application.  相似文献   
106.
107.
Insertion of a screw biopsy stylet into a thin-walled biopsy needle greatly enhances detection of the needle during ultrasound-guided percutaneous biopsy. This technique is helpful when precise needle-tip localization is needed for biopsies of small lesions.  相似文献   
108.
In this study, glycoconjugates of human skin varied in structure between cell types in an individual and often between individuals for a given cell type. Stored secretory material in dark cells of the sweat gland coil contained complex carbohydrate with terminal alpha-galactose, N-acetylgalactosamine, fucose, or sialic acid. The plasmalemma of clear cells in the secretory coil stained conspicuously for terminal alpha-N-acetylgalactosamine, and the cytosol of clear cells contained lectin-reactive glycogen in the majority of specimens. Superficial and deep cells of the sweat duct evidenced plasmalemmal glycoconjugate with terminal N-acetylgalactosamine. However, only the superficial cell plasmalemma in the duct stained for terminal alpha-N-acetylgalactosamine, fucose, and sialic acid. In several specimens, only the deep cells in the sweat duct revealed plasmalemmal glycoconjugate with terminal beta-galactose. Sebaceous glands alone displayed lectin affinity demonstrative of terminal alpha-galactose and like other sites stained for terminal beta-galactose and alpha-N-acetylgalactosamine. The epithelium in epidermis and hair follicles appeared similar, except for epidermis failing to evidence fucose and alpha-N-acetylgalactosamine with certain lectins. Both underwent changes in glycoconjugate composition with cell maturation. Skin from control subjects and patients with cystic fibrosis did not differ in lectin-binding properties. Abnormalities observed in cystic fibrosis specimens included decreased volume of sebaceous glands and, in two cases, increased infiltration of macrophages staining for terminal N-acetylgalactosamine.  相似文献   
109.
Garel  LA; Belli  D; Grignon  A; Roy  CC 《Radiology》1987,165(3):639-641
Percutaneous cholecystography was performed on 13 children who had biliary system abnormalities: two had biliary hypoplasia, five had sclerosing cholangitis, three had cirrhosis, two had distal choledochal obstruction, and one had an obstructed portoenterostomy. In 12 patients transcholecystic cholangiography showed, without significant complications, the intra-and extrahepatic bile ducts. In one patient with primary sclerosing cholangitis, the intrahepatic bile ducts were not opacified satisfactorily; dilatation of the gallbladder required surgical drainage. The transcholecystic technique is indicated when the intrahepatic bile ducts are either mildly dilated or not dilated.  相似文献   
110.
We report an analysis of the results obtained in our first 100 studies with indium-111-oxine labelled leukocyte scintigraphy, a diagnostic technique which has recently become available for clinical evaluation within Australia. We used this technique to assess patients with suspected sepsis or inflammation after other commonly used investigations had failed to confirm a diagnosis. Four patient subgroups were evaluated: fever of unknown origin; suspected abdominal or postoperative sepsis; suspected active inflammatory bowel disease; and suspected sepsis or inflammation of bones or joints. The course of all patients was followed for at least three months to establish the accuracy of the technique. The leukocyte labelling procedure took 90 min and imaging was carried out typically 3-6, 24 and occasionally 48 h after reinjection of the labelled autologous leukocytes. In one patient labelling of leukocytes was unsuccessful. In the remaining 99 studies the overall sensitivity of leukocyte scintigraphy was 88% (36 of 41 patients with a proved inflammatory or infective disease focus had positive scan findings); and the specificity was 95% (55 of 58 cases with no proved disease focus had normal scan findings). This series supports the use of this method as the imaging procedure of choice in nuclear medicine for the evaluation of suspected acute sepsis (symptoms less than four weeks' duration), of inflammatory bowel disease and of suspected infections involving appendicular bones which contain no active bone marrow. It is also a useful secondary scintigraphic procedure, after gallium-67-citrate scintigraphy, in patients with suspected infective disorders of more than four weeks' duration.  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