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   18133篇
  免费   929篇
  国内免费   61篇
耳鼻咽喉   362篇
儿科学   392篇
妇产科学   355篇
基础医学   3161篇
口腔科学   442篇
临床医学   1645篇
内科学   3048篇
皮肤病学   413篇
神经病学   1906篇
特种医学   963篇
外科学   2570篇
综合类   137篇
一般理论   2篇
预防医学   856篇
眼科学   551篇
药学   1205篇
中国医学   22篇
肿瘤学   1093篇
  2022年   102篇
  2021年   227篇
  2020年   139篇
  2019年   227篇
  2018年   295篇
  2017年   222篇
  2016年   368篇
  2015年   396篇
  2014年   435篇
  2013年   567篇
  2012年   1036篇
  2011年   990篇
  2010年   606篇
  2009年   634篇
  2008年   862篇
  2007年   1024篇
  2006年   1045篇
  2005年   1070篇
  2004年   994篇
  2003年   905篇
  2002年   952篇
  2001年   386篇
  2000年   297篇
  1999年   293篇
  1998年   249篇
  1997年   209篇
  1996年   175篇
  1995年   152篇
  1994年   130篇
  1993年   116篇
  1992年   149篇
  1991年   165篇
  1990年   167篇
  1989年   165篇
  1988年   166篇
  1987年   123篇
  1986年   108篇
  1985年   127篇
  1984年   123篇
  1983年   88篇
  1982年   82篇
  1981年   96篇
  1979年   112篇
  1978年   85篇
  1977年   91篇
  1976年   80篇
  1975年   81篇
  1974年   86篇
  1973年   78篇
  1972年   84篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
41.
Digital volume tomography (DVT) is an extension of panoramic tomography. With this diagnostic technique, characterized by high resolution, a narrow section width (0.125 mm) and three-dimensional display, small pathological processes can be well visualized. Twenty-five patients with the history of a progressive hearing loss were examined with DVT (Accu-I-tomo, Morita, Japan). The results were compared with pre- and intraoperative findings to evaluate the diagnostic value of DVT in cases of erosion of the ossicular chain. With high resolution and artifact-free demonstration of the middle ear and the ossicular chain, it was possible to define its continuity preoperatively by DVT in all 25 cases. An intact ossicular chain was found by DVT in 13 cases and was later confirmed by surgery. The predicted erosion of the ossicles was verified in 12 patients, and a tympanoplasty type III was performed. Digital volume tomography is an excellent technique to examine the middle ear cleft and inner ear, and expands the application of diagnostic possibilities in the lateral skull base. Therefore, improvement in preoperative diagnosis is achieved along with more accurate planning of the surgical procedure. Digital volume tomography delivers a small radiation dose with a high resolution and a low purchase price for the equipment.  相似文献   
42.
H S U  R Werner  D Wong 《Transplantation》1987,43(4):485-488
Brattleboro rats manifest chronic diabetes insipidus as a result of the genetic deficiency of hypothalamic vasopressin. When basal hypothalamic tissue derived from adult F344 rats was implanted as cell suspensions or tissue blocks in the supraoptic regions of these animals, concentration of urine together with reduced urine output and water intake was observed in some animals. Histologic examination of the grafted brains from the responding animals revealed neuronal cells at the implant sites and vasopressin-staining fibers in the median eminence. This study demonstrates the feasibility of the grafting of adult cerebral tissues to correct a genetic hormonal deficiency.  相似文献   
43.
    
Ohne Zusammenfassung  相似文献   
44.
OBJECTIVE: Transmission of Staphylococcus aureus via air may play an important role in healthcare settings. This study investigates the impact of barrier precautions on the spread of airborne S. aureus by volunteers with experimentally induced rhinovirus infection (ie, the common cold). DESIGN: Prospective nonrandomized study. SETTING: Wake Forest University School of Medicine (Winston-Salem, NC).Participants. A convenience sample of 10 individuals with nasal S. aureus carriage selected from 593 students screened for carriage. INTERVENTION: Airborne S. aureus dispersal was studied in the 10 participants under the following clothing conditions: street clothes, surgical scrubs, surgical scrubs and a gown, and the latter plus a face mask. After a 4-day baseline period, volunteers were exposed to a rhinovirus, and their clinical course was followed for 12 days. Daily swabs of nasal specimens, pharynx specimens, and skin specimens were obtained for quantitative culture, and cold symptoms were documented. Data were analyzed by random-effects negative binomial models. RESULTS: All participants developed a common cold. Incidence rate ratios (IRRs) indicated that, compared with airborne levels of S. aureus during sessions in which street clothes were worn, airborne levels decreased by 75% when surgical scrubs were worn (P<.001), by 80% when scrubs and a surgical gown were worn (P<.001), and by 82% when scrubs, a gown, and a face mask were worn (P<.001). The addition of a mask to the surgical scrubs and gown did not reduce the airborne dispersal significantly (IRR, 0.92; P>.05). Male volunteers shed twice as much S. aureus as females (incidence rate ratio, 2.04; P=.013). The cold did not alter the efficacy of the barrier precautions. CONCLUSIONS: Scrubs reduced the spread of airborne S. aureus, independent of the presence of a rhinovirus-induced cold. Airborne dispersal of S. aureus during sessions in which participants wore surgical scrubs was not significantly different from that during sessions in which gowns and gowns plus masks were also worn.  相似文献   
45.
Thirteen children with acute lymphoblastic leukemia (ALL) were investigated before and during cytotoxic therapy. EEG findings were correlated with the clinical course and the therapy protocol and compared with normal data obtained from 295 healthy children. Frequency analysis of the background activity of the EEG revealed an initial slowing of the background activity prior to therapy and further slowing each time a combination of vincristine (VCR), daunorubicine (DAU) or adriblastine (ADR), prednisone (FRED), and L-asparaginase (L-ASP) was administered. The slowing of the background activity correlated only with the administration of these drugs. DAU, ADR, and FRED are not known to influence the EEG; therefore, VCR and L-ASP remain the primary candidates responsible for the central nervous system alteration.  相似文献   
46.
Prolonged physical exercise is associated with multiple changes in blood hemostasis. Eccentric muscle activation induces microtrauma of skeletal muscles, inducing an inflammatory response. Since there is a link between inflammation and coagulation we speculated that downhill running strongly activates the coagulation system. Thirteen volunteers participated in the Tyrolean Speed Marathon (42,195 m downhill race, 795 m vertical distance). Venous blood was collected 3 days (T1) and 3 h (T2) before the run, within 30 min after finishing (T3) and 1 day thereafter (T4). We measured the following key parameters: creatine kinase, myoglobin, thrombin-antithrombin complex, prothrombin fragment F1 + 2, D-dimer, plasmin-alpha(2)-antiplasmin complexes, tissue-type plasminogen activator antigen, plasminogen-activator-inhibitor-1 antigen and thrombelastography with ROTEM [intrinsic pathway (InTEM) clotting time, clot formation time, maximum clot firmness, alpha angle]. Thrombin generation was evaluated by the Thrombin Dynamic Test and the Technothrombin TGA test. Creatine kinase and myoglobin were elevated at T3 and further increased at T4. Thrombin-antithrombin complex, prothrombin fragment F1 + 2, D-dimer, plasmin-alpha(2)-antiplasmin complexes, tissue-type plasminogen activator antigen and plasminogen-activator-inhibitor-1 antigen were significantly increased at T3. ROTEM analysis exhibited a shortening of InTEM clotting time and clot formation time after the marathon, and an increase in InTEM maximum clot firmness and alpha angle. Changes in TGA were indicative for thrombin generation after the marathon. We demonstrated that a downhill marathon induces an activation of coagulation, as measured by specific parameters for coagulation, ROTEM and thrombin generation assays. These changes were paralleled by an activation of fibrinolysis indicating a preserved hemostatic balance.  相似文献   
47.
PURPOSE: Amiodarone (AMIO), a widely used anti-arrhythmic drug, has been shown to reduce the incidence of atrial fibrillation after cardiac surgery and also to exert immunomodulatory actions in vitro and proinflammatory effects in vivo. The present study investigated the immunomodulatory properties of AMIO in the inflammatory response induced by cardiac surgery with cardiopulmonary bypass (CPB). METHODS: In this double-blind, placebo-controlled trial, 20 patients undergoing elective coronary artery bypass graft were randomized to receive placebo or AMIO 600 mg day(-1) orally for seven days before surgery and 45 mg hr(-1) intravenously for 48 hr postoperatively. Plasma levels of the proinflammatory markers C-reactive protein (CRP), fibrinogen (FBG), tumour necrosis factor (TNF)-alpha, interleukin (IL)-6 and monocyte chemoattractant protein (MCP)-1, and the antiinflammatory marker IL-10, were compared before and after surgery. RESULTS: Ninety-six hours after start of surgery, plasma levels of FBG had more than doubled (2.2 +/- 0.5-fold increase, P < 0.0001). Overall, FBG formation was significantly increased in the AMIO group (P = 0.048). Monocyte chemoattractant protein 1 secretion transiently increased four hours after start of surgery (6.6 +/- 4.5-fold increase) but rapidly declined thereafter, (P < 0.0001). There was a trend toward higher MCP-1 plasma concentrations in the AMIO group (P = 0.13). The plasma levels of CRP, TNF-alpha, IL-6 and Il-10 changed significantly over time, but were not altered by AMIO treatment. CONCLUSION: In the inflammatory response induced by cardiac surgery with CPB, our data suggest that AMIO treatment is associated with a selective trend toward proinflammatory actions.  相似文献   
48.
AIMS: This study evaluates feasibility, safety, and efficacy of magnetic remote-controlled accessory pathway (AP) ablation. METHODS AND RESULTS: The novel magnetic navigation system (MNS) (Niobe, Stereotaxis) creates a steerable magnetic field (0.08 T) controlling the distal magnetic tip of an ablation catheter. In conjunction with a catheter advancer system (Cardiodrive, Stereotaxis) remote catheter ablation is enabled. Conventional electrophysiology study identified AP conduction in 59 patients (37 males, 36+/-14 years, 60 APs). First generation 1-magnet tip (1-M) (group I, n=18), second generation bipolar 3-magnet tip (3-M) (group II, n=27), and third generation quadripolar 3-magnet tip catheters (3-M quad.) (group III, n=14) were used for magnetic remote-controlled ablation. Successful AP ablation was achieved in 67% (group I), 85% (group II), and 92% (group III). A significant decrease of median [IQR: Q1-Q3] fluoroscopy time and dosage was observed: 21.2 [12.1-33.8] min, 1110 [395-3234] microGym2 (group I); 6.5 [4.4-15.4] min, 290 [129-489] microGym2 (group II), and 4.9 [3.4-8.0] min, 129 [74-270] microGym2 (group III). Mean procedure time (217+/-67 min; 182+/-68 min, and 172+/-90 min) significantly decreased in group III. Median number [Q1-Q3] of radiofrequency current applications in groups I, II, and III was 4 [2-9], 4 [2-6], and 2 [2-4], respectively. No complications occurred. CONCLUSION: Remote AP ablation is safe and feasible using the novel MNS. Introduction of the 3-magnet quadripolar ablation catheter significantly improved the efficacy of the procedure.  相似文献   
49.
Sleeping sickness is a widely distributed disease in great parts of Africa. It is caused by Trypanosoma brucei gambiense and rhodiense, transmitted by the Tse-Tse fly. After a hemolymphatic stage, the parasites enter the central nervous system where they cannot be reached by hydrophilic drugs. To potentially deliver the hydrophilic antitrypanosomal drug diminazene diaceturate to the brain of infected mice, the drug was formulated as lipid-drug conjugate (LDC) nanoparticles (NP) by combination with stearic- (SA) and oleic acid (OA). To estimate the in vivo compatibility, the particles were incubated with human granulocytes. Because as potential delivery mechanism the absorption of specific serum proteins (ApoE, Apo AI and Apo AIV) was found to be responsible for the delivery of nanoparticles to the brain, demonstrated using PBCA nanoparticles coated with polysorbate 80 (LDL uptake mechanism) the nanoparticles were incubated with mouse serum and the adsorption pattern was determined using the 2-D PAGE technique. As a result of this study, the cytotoxic potential was shown to decrease when diminazene is part of the particle matrix compared to pure fatty acid nanoparticles and the mouse serum protein adsorption pattern differs from the samples studied earlier in human serum. Especially, the fact concerning Apo-E that could be detected when the particles were incubated in human serum is absent after the mouse serum incubation, potentially, is a critical point for the delivery via the LDL-uptake mechanism but the data demonstrate that LDC nanoparticles, with 33% (wt/wt) drug loading capacity possess the potential to act as a delivery system for hydrophilic drugs like diminazene diaceturate and that further studies have to demonstrate the usability as a brain delivery system.  相似文献   
50.
Boerhaave’s syndrome is a life-threatening disease with a high mortality. With regard to the heterogeneity of treatment strategies, no comparative studies exist and recommendations remain controversial. Seventeen cases of Boerhaave’s syndrome operated on between 1989 and 2000 at our hospital were reviewed retrospectively to compare the time period between perforation and diagnosis, and the morbidity and mortality among the different treatment options. In addition, we conducted a meta-analysis of the literature including all series containing five or more patients and compared the findings with our own data. Our patients with a perforation history of less than 12 hours showed significantly fewer signs of sepsis compared to patients with a history of more than 12 hours. In a comparison of patients with primary repair vs. patients treated with esophageal resection or an exclusion operation, no differences were found. In the literature, patients with a long period of perforation (more than 24 hours) were treated more often with an esophageal resection than patients with primary repair. In cases of Boerhaave’s syndrome, primary suturing of the esophageal perforation should be reserved only for those patients presenting within 12 hours after perforation. In all other cases, depending on the extent of the tissue damage, a two-stage esophageal resection with cervical esophagostomy and gastrostomy is recommended as the safest treatment.  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