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   13202篇
  免费   607篇
  国内免费   81篇
耳鼻咽喉   178篇
儿科学   262篇
妇产科学   251篇
基础医学   1588篇
口腔科学   708篇
临床医学   1033篇
内科学   3251篇
皮肤病学   237篇
神经病学   1102篇
特种医学   289篇
外科学   2113篇
综合类   70篇
一般理论   6篇
预防医学   896篇
眼科学   258篇
药学   771篇
中国医学   54篇
肿瘤学   823篇
  2024年   13篇
  2023年   126篇
  2022年   256篇
  2021年   483篇
  2020年   278篇
  2019年   378篇
  2018年   450篇
  2017年   326篇
  2016年   325篇
  2015年   391篇
  2014年   568篇
  2013年   704篇
  2012年   1138篇
  2011年   1130篇
  2010年   629篇
  2009年   565篇
  2008年   917篇
  2007年   892篇
  2006年   803篇
  2005年   764篇
  2004年   654篇
  2003年   556篇
  2002年   538篇
  2001年   86篇
  2000年   76篇
  1999年   82篇
  1998年   108篇
  1997年   69篇
  1996年   63篇
  1995年   56篇
  1994年   48篇
  1993年   41篇
  1992年   34篇
  1991年   30篇
  1990年   17篇
  1989年   16篇
  1988年   15篇
  1987年   22篇
  1986年   27篇
  1985年   18篇
  1984年   18篇
  1983年   10篇
  1982年   11篇
  1981年   17篇
  1980年   21篇
  1979年   15篇
  1978年   9篇
  1977年   14篇
  1975年   17篇
  1974年   11篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
Background: Gastro-gastric fistulas and marginal ulcers are frequent and serious complications of gastric compartmentalization procedures for obesity. Methods: The authors analyzed 810 patients after 911 operations for gastro-gastric fistulas and marginal ulcers over an 8-year period. All patients underwent a form of gastric bypass, in which a pouch is constructed along the lesser curvature of the stomach. The outlet of the pouch was restricted with a prosthetic band. In the first 189 patients (Group I), the pouch and stomach were stapled in continuity or partially divided. In the next 222 patients (Group II), segments were stapled and separated by transection. In the remaining 492 cases (Group III), in addition to transection of the stomach, a limb of jejunum was interposed between the pouch and excluded stomach. Stapled anastomoses were done in Group I and II patients and a portion of Group III patients. The remaining patients underwent hand-sewn anastomosis. Results: Gastro-gastric fistulas occurred in 49% of the patients in Group I, 2.6% of those in Group II, and 0% of those in Group III. In stapled anastomosis, the incidence of marginal ulceration in Groups I, II, and III were 8.5%, 5.4%, and 5.1%, respectively. In a subset of Group III patients, in whom a two-layer, hand-sewn anastomosis was done, the incidence was 1.6% when the outer layer was not absorbable and 0% when both layers were absorbable. Conclusions: Gastro-gastric fistulas and marginal ulcerations are likely the result of breakdown of the mucosa resulting from migrating staples and other foreign material. Lack of integrity of the gastric lining facilitates the action of the gastric digestive process. Transection of gastric segments with interposition of jejunum prevents gastro-gastric fistula formation. An intact serosa appears to block the digestion of bowel wall by gastric enzymes. Our early data suggest that the use of absorbable sutures at the gastrojejunostomy significantly decreases the incidence of marginal ulceration.  相似文献   
72.
BACKGROUND AND OBJECTIVE: Many laser centres utilise various transparent membranes during treatment sessions with Q-switched lasers to prevent or reduce tissue splatter, thereby reducing the aerosolised biohazard of cellular debris to operator and laser. STUDY DESIGN/MATERIALS AND METHODS: We performed a series of experiments with the Q-Switched Nd:YAG laser, a selection of 11 varieties of membrane and a power meter in order to ascertain which of the membranes was the most effective protector concerning transmission of laser energy. Other mechanical properties such as transparency, strength, ease of application, and flexibility were taken into account. RESULTS: Tegaderm (overall average 94% transmission), Cling Film (93%), Bioclusive (89%), Opsite (91%), and Microwave Cling Film (87%) all consistently performed well in pure transmission terms, whereas other membranes tested such as Acetate (74%), Grades of Melinex (75%, 72%, 75%), 2nd Skin (74%), and Perspex (68%) were unsuitable as protection. CONCLUSION: Cling Film proved to be the best all round membrane. We recommend its use for operator and laser protection against the tissue spatter produced from the Q-Switched Nd:YAG laser.  相似文献   
73.
We describe the safe and effective use of the combination of clozapine and ECT in a patient with schizophrenia who had lost responsiveness to clozapine alone. We suggest further investigation to define the role of combined clozapine-ECT treatment in the management of treatment-resistant schizophrenia.  相似文献   
74.
A simple auto-evaluation sheet is presented for the proper assessment of the patient's condition after surgery. Stress is put not only on weight loss, but on other important factors as well.  相似文献   
75.
PURPOSE: Preclinical studies indicate that gefitinib (Iressa, ZD1839; AstraZeneca, Wilmington, DE), an orally active epidermal growth factor receptor tyrosine kinase inhibitor, may enhance antitumor efficacy of cytotoxics, and combination with paclitaxel and carboplatin had acceptable tolerability in a phase I trial. Gefitinib monotherapy demonstrated unparalleled antitumor activity for a biologic agent, with less toxicity than docetaxel, in phase II trials in refractory, advanced non-small-cell lung cancer (NSCLC). This phase III, randomized, placebo-controlled, double-blind trial evaluated gefitinib plus paclitaxel and carboplatin in chemotherapy-naive patients with advanced NSCLC. PATIENTS AND METHODS: Patients received paclitaxel 225 mg/m(2) and carboplatin area under concentration/time curve of 6 mg/min/mL (day 1 every 3 weeks) plus gefitinib 500 mg/d, gefitinib 250 mg/d, or placebo. After a maximum of six cycles, daily gefitinib or placebo continued until disease progression. End points included overall survival, time to progression (TTP), response rate (RR), and safety evaluation. Results A total of 1,037 patients were recruited. Baseline demographic characteristics were well balanced. There was no difference in overall survival (median, 8.7, 9.8, and 9.9 months for gefitinib 500 mg/d, 250 mg/d, and placebo, respectively; P =.64), TTP, or RR between arms. Expected dose-related diarrhea and skin toxicity were observed in gefitinib-treated patients, with no new significant/unexpected safety findings from combination with chemotherapy. Subset analysis of patients with adenocarcinoma who received > or = 90 days' chemotherapy demonstrated statistically significant prolonged survival, suggesting a gefitinib maintenance effect. CONCLUSION: Gefitinib showed no added benefit in survival, TTP, or RR compared with standard chemotherapy alone. This large, placebo-controlled trial confirmed the favorable gefitinib safety profile observed in phase I and II monotherapy trials.  相似文献   
76.
Myelodysplastic syndromes and acute myeloid leukemia (AML) are heterogeneous disorders in which conflicting results in apoptosis and multidrug resistance (MDR) have been reported. We have evaluated by multiparameter flow cytometry the expression of apoptosis- (APO2.7, bcl-2, and bax) and MDR-related proteins [P-glycoprotein (P-gp), multidrug resistance protein (MRP), and lung resistance protein (LRP)] specifically on bone marrow (BM) CD34+ cells, and their major CD32-/dim and CD32+ subsets, in de novo AML (n=90), high-risk myelodysplastic syndrome (n=9), and low-risk myelodysplastic syndrome (n=21) patients at diagnosis, and compared with normal BM CD34+ cells (n=6). CD34+ myeloid cells from AML and high-risk myelodysplastic syndrome patients displayed higher expression of bcl-2 (P <0.0001) and lower reactivity for APO2.7 (P=0.002) compared with low-risk myelodysplastic syndrome and normal controls. Similar results applied to the two predefined CD34+ myeloid cell subsets. No significant differences were found in the expression of P-gp, MRP, and LRP between low-risk myelodysplastic syndrome patients and normal BM, but decreased expression of MRP (P <0.03) in AML and high-risk myelodysplastic syndromes and P-gp (P=0.008) in high-risk myelodysplastic syndromes were detected. Hierarchical clustering analysis showed that low-risk myelodysplastic syndrome patients were clustered next to normal BM samples, whereas high-risk myelodysplastic syndromes were clustered together and mixed with the de novo AML patients. In summary, increased resistance to chemotherapy of CD34+ cells from both AML and high-risk myelodysplastic syndromes would be explained more appropriately in terms of an increased antiapoptotic phenotype rather than a MDR phenotype. In low-risk myelodysplastic syndromes abnormally high apoptotic rates would be restricted to the CD34- cell compartments.  相似文献   
77.
PURPOSE: To assess tolerance and efficacy of preoperative treatment with uracil/tegafur and radiotherapy (RT) followed by surgery and postoperative flurouracil (FU)/leucovorin (LV) in patients with rectal cancer. PATIENTS AND METHODS: Patients (n = 94) with potentially resectable tumors, ultrasound at stages T2N+ (n = 4), T3 (n = 77), T4 (n = 13) were treated with UFT (400 mg/m2/d, 5 days a week for 5 weeks) and concomitant RT to the pelvis (45 Gy; 1.8 Gy/d over 5 weeks). Patients underwent surgery 5 to 6 weeks later followed by four cycles of FU/LV. Primary end points included downstaging, pathologic responses, and sphincter-preserving surgery. Secondary end points were recurrence-free survival and overall survival. RESULTS: All patients received the full RT dose. Fifteen patients (16%) needed UFT dose reduction. Preoperative G3+ toxicities included diarrhea (14%), leukopenia (1%), thrombocytopenia (1%), and nausea (4%). The downstaging rate was 54%, pathologic complete response (pCR) was 9% and, in an additional 23%, there were only residual microscopic foci. When cellular viability criteria were taken into account, the pCR was 15%. From 43 patients with abdominoperineal resection indication, 11 (25%) had sphincter-preserving surgery performed. Postoperative scheduled chemotherapy dose was not administered to 24% of patients because of G3+ toxicity (diarrhea, 8%; mucositis, 9%; and leukopenia, 7%). Patients with downstaging had significantly higher survival and recurrence-free survival rates than those without. At 3 years, actuarial patterns of failure were pelvic, 5% and distant, 11%. OS was 75%. CONCLUSION: UFT combined with RT is safe and effective. In resectable rectal cancer, if preoperative treatment is considered, this approach can be an option.  相似文献   
78.
Objective: To study the insulin-like growth factor-1 (IGF-1) axis in hirsute women.

Design: Controlled clinical study.

Setting: Tertiary care institutional hospital.

Patient(s): Forty hirsute women and 17 women with normal menstrual cycles.

Intervention(s): Basal and ACTH-stimulated samples were obtained, and sampling was repeated 1 (gonadal stimulation) and 21 (gonadal suppression) days after a single 3.75-mg IM dose of triptorelin. Controls did not receive triptorelin for ethical reasons.

Main Outcome Measure(s): Serum GH, IGF-1, IGF-binding protein-3 (IGFBP-3), insulin, glucose, total testosterone, sex hormone-binding globulin, E2, and gonadotropin levels. Basal and ACTH-stimulated steroid precursors were measured.

Result(s): Patients with idiopathic hirsutism were identified by normal serum androgen levels (n = 17). Those with functional ovarian hyperandrogenism (n = 15) were identified by an increase in the serum testosterone level that normalized during gonadal suppression, whereas those with functional adrenal hyperandrogenism (n = 8) were identified by an initial increase in the testosterone level that persisted during gonadal suppression. The adrenal hyperandrogenism group had increased IGF-1 levels compared with the control, idiopathic hirsutism, and ovarian hyperandrogenism groups. Patients with ovarian hyperandrogenism had normal IGF-1 concentrations, but their IGFBP-3 concentrations were lower than those of controls. No differences were observed in GH levels between any of the groups. These results persisted when the influence of age was corrected for.

Conclusion(s): The IGF-1 axis appears to be involved in the pathogenesis of hyperandrogenism, especially in patients with adrenal hyperandrogenism, who have a clear increase in IGF-1 levels. Moreover, patients with ovarian hirsutism have decreased IGFBP-3 concentrations, which might enhance IGF-1 bioavailability.  相似文献   

79.
80.
INTRODUCTION: Presence of circulating DNA in the serum of patients with cancer makes detection of tumour-specific genetic alterations feasible. OBJECTIVE: To study serum DNA concentration in patients diagnosed as having advanced Non-Small Cell Lung Cancer (NSCLC) and to evaluate its relationship with age, histology, stage, response, time-to-progression (TTP), and survival. METHODS: Serum DNA from 78 patients was purified and spectrophotometrically quantified. RESULTS: No significant correlations were found between serum DNA concentration and age, histology, response and survival. There was a significant correlation with respect to stage (IIIB = 408.75 ng/ml; IV = 478.74 ng/ml; p = 0.02). When patients were grouped according to DNA concentration, significant correlation with TTP was found; establishing a cut-off point at 500 ng/ml ([DNA] < 500 ng/ml TTP = 7.25 months, 95%CI: 3.5-5.25; [DNA ] > or = 500 ng/ml TTP = 4.25 months, 95%CI: 2-6.5; p = 0.05). CONCLUSIONS: Using the present method, DNA concentration quantification appears to be simple, but with certain deficiencies due to inter-sample variability and low specificity. This is because total DNA concentration is measured without distinguishing as to whether it is tumour-related. We suggest that there is a correlation between DNA concentration and prognosis which enables an analysis of the natural history of the disease.  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