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   1707篇
  免费   67篇
  国内免费   7篇
耳鼻咽喉   30篇
儿科学   52篇
妇产科学   54篇
基础医学   178篇
口腔科学   210篇
临床医学   76篇
内科学   331篇
皮肤病学   27篇
神经病学   185篇
特种医学   16篇
外科学   299篇
综合类   5篇
预防医学   120篇
眼科学   25篇
药学   106篇
中国医学   25篇
肿瘤学   42篇
  2024年   1篇
  2023年   10篇
  2022年   23篇
  2021年   47篇
  2020年   33篇
  2019年   45篇
  2018年   47篇
  2017年   36篇
  2016年   43篇
  2015年   47篇
  2014年   59篇
  2013年   97篇
  2012年   157篇
  2011年   187篇
  2010年   102篇
  2009年   77篇
  2008年   121篇
  2007年   138篇
  2006年   135篇
  2005年   104篇
  2004年   80篇
  2003年   68篇
  2002年   62篇
  2001年   11篇
  2000年   9篇
  1999年   8篇
  1998年   7篇
  1997年   3篇
  1996年   2篇
  1995年   1篇
  1994年   2篇
  1993年   1篇
  1992年   2篇
  1991年   1篇
  1990年   2篇
  1988年   1篇
  1987年   1篇
  1985年   2篇
  1984年   2篇
  1983年   1篇
  1982年   2篇
  1978年   1篇
  1942年   1篇
  1914年   1篇
  1907年   1篇
排序方式: 共有1781条查询结果,搜索用时 62 毫秒
1.
INTRODUCTION: Transesophageal echocardiography (TEE) has become increasingly useful in the study of patients with suspected pulmonary thromboembolism. OBJECTIVE: The aim of this study was to prospectively evaluate the usefulness of TEE in the study of the distal part of the left pulmonary artery (LPA) as well as the influence of this procedure on total echocardiographic exam duration. METHODOLOGY: A prospective study in two groups of consecutive patients referred for TEE with a one- year interval between evaluation of Group A: 33 patients, 17 male, mean age 54 +/- 24 years, and Group B: 42 patients, 20 male, mean age 48 +/- 27 years (p = NS). The procedure was considered long when it took more than 3 min to evaluate the distal part of the LPA. RESULTS: In group A we were able to visualize the distal part of the LPA in 24 patients (73%) without significant prolongation of total exam duration in 16 patients (48% of group A). In one of the patients with suspected pulmonary thromboembolism thrombi were only observed in the distal part of the LPA. In group B we were able to visualize the distal part of the LPA in 36 patients (86%) without significant prolongation of total exam duration in 26 patients (61% of group B). CONCLUSIONS: 1. Visualization of the distal part of the LPA was possible in more patients, and with TEE time prolongation in less patients, in group B. These differences can be accounted for by the training of the operator in this technique. 2. The importance of visualization of this part of the LPA in guiding treatment in the subset of patients with pulmonary thromboembolism confirms the usefulness of this specific procedure.  相似文献   
2.
We describe the case of a pregnant woman with idiopathic pulmonary arterial hypertension, a responder in right heart catheterization, followed since the first trimester in outpatient consultations, admitted to hospital at 23 weeks gestation. She was treated with inhaled iloprost until delivery (at 34 weeks gestation) and continuous infusion of iloprost throughout the perioperative period and following days. This line of therapy has proved efficacious in previous cases. The authors present echocardiographic images that document acute changes in ventricular synchrony during inhalation of iloprost.  相似文献   
3.
N Ergen?  B Durgun  G Otük 《Die Pharmazie》1992,47(7):495-498
6-Methyl-2,4-heptandione (1) was coupled with diazonium salts of sulfanilamide (2) and 4-aminobenzoic acid (3). Resulting new hydrazones, namely 4-methyl-2-oxovaleraldehyde p-substituted phenylhydrazones 4 and 5, were refluxed with various hydrazines to synthesize the title compounds 6-15. Their structure elucidation was made on the basis of their analytical and spectroscopic data. The antibacterial activity was evaluated. Some of the compounds tested exerted moderate to potent antibacterial activity against Staphylococcus aureus, Staphylococcus epidermidis and Streptococcus pyogenes.  相似文献   
4.
5.
Hyperparathyroidism contributes significantly to decreased bone mineral density (BMD) in end-stage renal disease patients, but this negative influence is not homogeneous throughout the skeleton. We studied the BMD by dual-energy X-ray absorptiometry on total body and on different regions of the skeleton in 42 patients with severe hyperparathyroidism on hemodialysis. We also evaluated the relationship between different risk factors and BMD found on the regions examined in these patients. The legs and other sites where cortical bone predominate were mostly affected, whereas trabecular bone was relatively preserved. This is probably the result of the different effects of hyperparathyroidism on cortical and trabecular bone, but we cannot rule out the interference of ectopic calcifications and sclerotic lesions of vertebral end-plates falsely increasing lumbar spine BMD. The main determinants of low total-body BMD were, in order of importance, immobility, high intact parathyroid hormone levels, low body mass index, and low albumin. Eleven patients presented with pathologic fractures, mainly in the legs, and BMD was lower in this group than in patients without fractures. In conclusion, our study makes clear that hyperparathyroidism is a great threat to bone density in hemodialysis patients, mainly in the legs, the site mostly affected by fragility fractures in our patients. Physicians must worry not only with high parathyroid hormone levels, but also with the nutritional state of these patients.  相似文献   
6.
The purpose of this study was to investigate the antiproliferative activity of 2,3,9-trimethoxypterocarpan, a known pterocarpan with cytotoxic activity against many tumor cell lines, in a panel of four leukemia cell lines (HL-60, Molt-4, Jurkat, and K562) and on human peripheral blood mononuclear cells (PBMC). The pterocarpan showed IC50 ranging from 0.1 to 0.5 μg/ml at leukemic cells after 72 h of incubation, with K562 being the most resistant cell line. This compound seemed to be selective to tumor cell lines, since at a concentration of 10 μg/ml after 72 h, it only reduced 19% of viable peripheral mononuclear cells.  相似文献   
7.
Abdominal Stab Wounds in Children: an 18-Year Experience   总被引:1,自引:0,他引:1  
Objective: Evaluation of the diagnosis, management, and the role of selective treatment in children with abdominal stab wounds. Patients and Methods: 59 children (56 male and three female) were included in the study. The patients' median age was 11.8 years (range, 5–14 years). Time between injury and admission was about 3 h. Laparotomy was performed in 44 patients (74%). Solid organ injury was detected in 32 of these patients (73%) and could not be observed in twelve (27%). 15 patients (26%) were treated conservatively, and only one (6.6%) underwent laparotomy during the follow-up. The stomach was the most frequently injured organ (ten patients), followed by the intestines (nine patients). Types of surgical treatment were as follows: primary suture in 28 patients, resection-anastomosis in three, and osteotomy in two. Results: Some prognostic factors such as presence of abdominal organ evisceration and pneumoperitoneum were not significantly correlated with intraabdominal organ injury, whereas some other risk factors such as acute abdomen on admission (p < 0.002) or abdominal clinical and hemodynamic findings (p < 0.001) showed significant correlation with intraabdominal organ injury. The relative risk (odds ratio) of developing an intraabdominal organ injury was > 2 for patients with signs of an acute abdomen on admission. Postoperative complications were observed in five patients with organ injuries. None of our patients died. Conclusions: Conservative treatment can be safely performed in most children with abdominal stab injuries. Signs of major internal hemorrhage or generalized peritonitis are an absolute indication for emergency operation for abdominal stab wounds. Peritoneal penetrations, free air on the abdominal X-ray, and omental or intestinal evisceration are poor indicators of significant organ injuries, and patients presenting these signs shold be closely followed up for developing acute abdominal symptoms. Received: November 2, 2001; revision accepted: February 15, 2002  相似文献   
8.
Inflammatory events during Leishmania braziliensis infection in mice were investigated. Large lesions were directly correlated with the inflammatory reaction but not with parasite burden. Different L. braziliensis strains induce different paces of chemokine expression patterns, leading to diverse cell recruitment and differential inflammatory responses.  相似文献   
9.
In this report, we describe an investigation of the effects of Lutzomyia longipalpis sand fly salivary gland homogenates (SGH) on cytokine production and expression of costimulatory molecules on human monocytes, macrophages (Ms), and dendritic cells (DCs). SGH of L. longipalpis induced an increase in interleukin-6 (IL-6), IL-8 and IL-12p40 production but a decrease in tumor necrosis factor alpha and IL-10 production by lipopolysaccharida (LPS)-stimulated monocytes. We also examined the expression of costimulatory molecules on the surface of monocytes, Ms, and DCs. Whereas SGH affected the expression of these molecules on monocytes and Ms, it had little effect on these molecules on DCs. However, when DCs were generated from human monocytes in the presence of SGH, SGH inhibited the expression of costimulatory molecules. In addition, a decrease in the maturation of DCs induced by CD40L was observed in the presence of SGH. Finally, preincubating SGH with human sera containing anti-SGH-specific antibodies abolished the effects of SGH on cytokine production by LPS-stimulated monocytes.  相似文献   
10.
In order to determine if patients with a history of previous urothelial cell carcinoma (UCC) but with current normal urinary cytology have DNA damage in urothelial cells, the single-cell gel electrophoresis (comet) assay was conducted with cells obtained by urinary bladder washings from 44 patients (28 with a history of previous UCC). Increased DNA damage was observed in cytologically "normal" urothelial cells of patients with a history of UCC when compared with referents with no similar history and after correcting the data for smoking status and age (P < 0.018). Increased DNA damage also correlated with the highest tumor grade, irrespective of time or course of the disease after clinical intervention (Kendall tau correlation, 0.37, P = 0.016). Moreover, aneuploidy, as assessed by DNA content ratio (DCR; 75th/25th percentile of total DNA fluorescence of 50 comets/patient) was unaltered by smoking status, but increased with UCC grade: 1.39 +/- 0.12 (median +/- 95% confidence interval; referents); 1.43 +/- 0.11 (Grade I UCC; P = 0.264, against referents); 1.49 +/- 0.16 (Grade II UCC; P = 0.057); 1.57 +/- 0.16 (Grade III UCC; P = 0.003). Micronucleated urothelial cells (MNC) were also scored on Giemsa-stained routine cytological smears and were found not to correlate with DNA damage or DCR. MNC frequencies were higher for patients with a history of UCC and/or smoking than referents with neither history, but there was no statistical difference between groups. Taken together, these results suggest that the normal-appearing urothelium of patients resected for UCC still harbor genetically unstable cells.  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