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   669篇
  免费   54篇
  国内免费   22篇
耳鼻咽喉   1篇
儿科学   36篇
妇产科学   1篇
基础医学   66篇
口腔科学   9篇
临床医学   116篇
内科学   150篇
皮肤病学   10篇
神经病学   5篇
特种医学   123篇
外科学   30篇
综合类   29篇
预防医学   18篇
眼科学   28篇
药学   36篇
肿瘤学   87篇
  2024年   1篇
  2023年   1篇
  2022年   1篇
  2021年   7篇
  2020年   1篇
  2019年   6篇
  2018年   9篇
  2017年   6篇
  2016年   6篇
  2015年   14篇
  2014年   27篇
  2013年   18篇
  2012年   24篇
  2011年   30篇
  2010年   13篇
  2009年   24篇
  2008年   37篇
  2007年   37篇
  2006年   45篇
  2005年   29篇
  2004年   34篇
  2003年   33篇
  2002年   25篇
  2001年   30篇
  2000年   17篇
  1999年   11篇
  1998年   33篇
  1997年   22篇
  1996年   27篇
  1995年   23篇
  1994年   19篇
  1993年   22篇
  1992年   8篇
  1991年   4篇
  1990年   9篇
  1989年   5篇
  1988年   7篇
  1987年   4篇
  1986年   11篇
  1985年   8篇
  1984年   7篇
  1983年   6篇
  1982年   7篇
  1981年   7篇
  1980年   13篇
  1979年   3篇
  1978年   4篇
  1977年   4篇
  1976年   4篇
  1975年   2篇
排序方式: 共有745条查询结果,搜索用时 15 毫秒
31.
32.
有机硒化合物对白三烯B4生物合成的影响   总被引:4,自引:0,他引:4  
  相似文献   
33.
Mechanisms by which gastroplasty for morbid obesity causes weight loss are poorly understood. We studied the role of altered gastric emptying in 50 patients before surgery, 1-4 weeks after surgery, and 2-24 months after surgery using technetium-99m pentetate in water for liquid meals and a Tc-99m styrene divinylbenzene copolymer resin in oatmeal for semisolid meals. We determined the emptying half-times of the stomach before and after surgery in the proximal and distal compartments. The proximal compartment emptied promptly in the early and late postoperative periods. The distal compartment emptied liquids at rates similar to those before surgery, while the late postoperative emptying of semisolids was significantly faster. The stoma connecting the two compartments thus permits rapid transit of liquids and semisolids without delay of distal compartment emptying. No correlation was seen between the emptying half-times or changes thereof and eventual weight loss. Delayed gastric emptying is therefore not the mechanism for satiety and weight loss after gastroplasty has been performed.  相似文献   
34.
A commercially available repetitive-sequence-based PCR (rep-PCR) DNA fingerprinting assay adapted to an automated format, the DiversiLab system, enables rapid microbial identification and strain typing. We explored the performance of the DiversiLab system as a molecular typing tool for 69 Aspergillus isolates (38 A. fumigatus, 15 A. flavus, and 16 A. terreus isolates) had been previously characterized by morphological analysis. Initially, 27 Aspergillus isolates (10 A. fumigatus, 9 A. flavus, and 8 A. terreus isolates) were used as controls to create a rep-PCR-based DNA fingerprint library with the DiversiLab software. Then, 42 blinded Aspergillus isolates were typed using the system. The rep-PCR-based profile revealed 98% concordance with morphology-based identification. rep-PCR-based DNA fingerprints were reproducible and were consistent for DNA from both hyphae and conidia. DiversiLab dendrogram reports correctly identified all A. fumigatus (n = 28), A. terreus (n = 8), and A. flavus (n = 6) isolates in the 42 blinded Aspergillus isolates. rep-PCR-based identification of all isolates was 100% in agreement with the contiguous internal transcribed spacer (ITS) region (ITS1-5.8S-ITS2) sequence-based identification of the respective isolates. Additionally, the DiversiLab system could demonstrate strain-level differentiation of A. flavus and A. terreus. Automated rep-PCR may be a time-efficient, effective, easy-to-use, novel genotyping tool for identifying and determining the strain relatedness of fungi. This system may be useful for epidemiological studies, molecular typing, and surveillance of Aspergillus species.  相似文献   
35.
BACKGROUND: Systemic fungal infections remain the leading cause of mortality in patients with newly diagnosed acute myelogenous leukemia (AML) and high-risk myelodysplastic syndrome (MDS). The objective of the current study was to determine whether intravenous itraconazole (i.v. ITRA) reduced the incidence of probable/proven fungal infections in this group of patients, and compare the results with those of a historic control group treated with fluconazole plus itraconazole capsules (F+I). METHODS: Patients with AML and high-risk MDS who underwent induction chemotherapy received 200 mg of i.v. itraconazole over 60 minutes every 12 hours during the first 2 days followed by 200 mg given i.v. once daily. RESULTS: One hundred patients were enrolled, 96 of whom were evaluable. Approximately 48% of the patients in the group of patients treated with i.v. ITRA as well as in the F+I group completed prophylaxis. Nine patients (9%) in the study group developed either proven/probable fungal infections (Candida glabrata in 5 patients, C. tropicalis in 1 patient, C krusei in 1 patient, and Fusarium in 2 patients) compared with 3 patients (4%) with proven fungal infection in the historic control group (C. tropicalis in 1 patient and Aspergillus in 2 patients). There were no significant differences noted between the two groups with regard to the percentage of patients who developed proven/probable or possible fungal infection as well as with regard to survival. These results also were obtained after adjusting for relevant prognostic factors (creatinine and bilirubin). The most common toxicity encountered with the use of i.v. ITRA was NCI Grade 3-4 hyperbilirubinemia (6%). CONCLUSIONS: Despite its theoretic advantages, the authors found no evidence that i.v. ITRA is superior to itraconazole capsules, at least when the latter is combined with fluconazole.  相似文献   
36.
We investigated the in vitro activity of sequential itraconazole and caspofungin against 10 isolates of Aspergillus fumigatus. Previous exposure of A. fumigatus to itraconazole resulted in dose-dependent enhanced effects of caspofungin and vice versa. Our finding suggests a preferential role for azole-caspofungin sequential combinations and merits further in vivo investigation.  相似文献   
37.
Two neonates with arrhythmias and the long QT syndrome are described. The arrhythmias were detected in utero and both infants were apparently well after birth. The first infant, although well, had a bradycardia for the first 9 days of life. A normal heart rate was documented at 10 days but a prolonged QT interval was not appreciated on the ECG. He was discharged from hospital but died suddenly and unexpectedly 3 days later. A post-mortem examination failed to find a cause for his death which therefore fell into the category of the sudden infant death syndrome (SIDS). A retrospective analysis of the perinatal electrocardiogram showed a probable junctional rhythm with 2:1 conduction to the ventricle; the QT interval was prolonged at 0.52 seconds (QTC = 0.63). The second infant had a QT interval of 0.52 seconds (QTC = 0.54) and frequent ventricular premature beats on a 24-hour electrocardiogram. She was treated with propranolol and remains well 2 years later. Sudden infant death has often been described in the siblings of children with the long QT syndrome and one other report described a case of SIDS which was said to have had a prolonged QT interval on the perinatal ECG. This report, however, provides unquestionable evidence, in one case, of an association between the long QT syndrome and SIDS.  相似文献   
38.
Legionella pneumonia in cancer patients   总被引:1,自引:0,他引:1  
Legionella is an important cause of nosocomial and community-acquired pneumonia in both immunocompetent and immunosuppressed patients worldwide; however, the clinical course and optimal antibiotic therapy of Legionella pneumonia (LP) in patients with cancer is uncertain. We studied retrospectively the risk factors, clinical manifestations, and outcome of 49 cancer patients with a positive Legionella culture or direct fluorescent antibody (DFA) over a 13-year period (1991-2003). The majority of patients (82%) had an underlying hematologic malignancy, and 37% were bone marrow transplant recipients; 80% of the patients had active malignancy. Lymphopenia (47%), use of systemic corticosteroids (41%), and chemotherapy (63%) were the most common underlying conditions. The laboratory diagnosis was established by positive Legionella culture (n = 8, 16%), DFA (n = 29, 59%), or both (n = 12, 25%). In 4 patients (8%), a positive DFA was deemed to represent false-positive results. There was no temporal or geographic clustering of cases. The majority of the cases had multilobar (61%) or bilateral (55%) pulmonary involvement.The mean time to response to therapy was 8 days; 18 patients (37%) developed complications requiring prolonged duration of treatment (mean, 25 d). The case-fatality rate was 31%. Two patients had relapse of LP despite appropriate therapy. Improved outcome, especially in those with severe pneumonia, seemed to correlate with the use of a combination of antibiotics. LP is an uncommon infection in our patient population but is associated with significant morbidity and mortality. Treatment of LP in cancer patients may require a prolonged course with a regimen that includes a newer macrolide or quinolone.  相似文献   
39.
Toloxatone is a reversible MAOA-inhibitor, marketed as antidepressant (Humoryl®), with an original chemical structure. It differs from first generation irreversible MAOIs, known to induce covalent bonds with the enzyme active site. In order to understand the mechanism of the reversible inactivation of the MAO, as a first step, a detailed structural and electronic analysis was undertaken. An X-ray diffraction-crystallographic study showed that toloxatone is a planar molecule and brought to light hydrogen bonds and π-π interactions. MO calculations confirmed the planar structure as energetically favoured. Electronic analysis demonstrated a delocalization of both ring systems. The combined results give evidence for the potential of toloxatone to participate in reversible, long distance interactions with an appropriate partner.  相似文献   
40.
This article reviews the usefulness and importance of written information, specifically leaflets, being given to patients. Evidence suggesting how both patient and doctor may benefit from the giving of written information is reviewed. Identification of good practice relating to the content and readability of leaflets is discussed. An argument is put forward that the giving of written information is an under-utilized resource in contributing to improving patient outcomes but that this may be changing with the increasing use of patient leaflet databases. The advantages and disadvantages of computer- generated patient leaflets are discussed and desirable further areas of research on computer-generated leaflets are proposed.   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