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   2321篇
  免费   191篇
  国内免费   2篇
耳鼻咽喉   18篇
儿科学   108篇
妇产科学   71篇
基础医学   380篇
口腔科学   47篇
临床医学   210篇
内科学   402篇
皮肤病学   33篇
神经病学   348篇
特种医学   96篇
外国民族医学   1篇
外科学   245篇
综合类   36篇
一般理论   1篇
预防医学   125篇
眼科学   70篇
药学   182篇
中国医学   2篇
肿瘤学   139篇
  2023年   18篇
  2022年   28篇
  2021年   66篇
  2020年   34篇
  2019年   50篇
  2018年   69篇
  2017年   33篇
  2016年   42篇
  2015年   41篇
  2014年   59篇
  2013年   94篇
  2012年   142篇
  2011年   145篇
  2010年   62篇
  2009年   70篇
  2008年   117篇
  2007年   82篇
  2006年   101篇
  2005年   130篇
  2004年   92篇
  2003年   85篇
  2002年   80篇
  2001年   69篇
  2000年   60篇
  1999年   67篇
  1998年   30篇
  1997年   21篇
  1996年   21篇
  1995年   15篇
  1994年   13篇
  1993年   22篇
  1992年   55篇
  1991年   44篇
  1990年   47篇
  1989年   44篇
  1988年   44篇
  1987年   26篇
  1986年   35篇
  1985年   30篇
  1984年   31篇
  1983年   25篇
  1982年   22篇
  1981年   12篇
  1979年   17篇
  1978年   9篇
  1977年   12篇
  1976年   10篇
  1974年   10篇
  1972年   12篇
  1970年   9篇
排序方式: 共有2514条查询结果,搜索用时 0 毫秒
21.
22.
This retrospective study assesses and compares perioperative parameters in two groups of patients treated by different operative techniques of laparoscopic surgical staging (LASS) for uterine cancer. Between April 1996 and May 2005, 119 consecutively selected women with cervical cancer (n=30) or clinical stage I endometrial cancer (n=89) underwent laparoscopic assisted vaginal hysterectomy (LAVH), total laparoscopic hysterectomy (TLH) or radical laparoscopic assisted vaginal hysterectomy (RALVH) plus bilateral salpingo-oophorectomy (BSO) and/or lymph node dissection (LND) during a primary surgical procedure using an electrosurgery (ELC, n=37) or ultrasonic (US, n=82) operative technique (harmonic shears, UltraCision). The UltraCision was used as a primary method of dissection and hemostasis from 1999. We were unable to perform prompt and thorough hemostasis in 2 patients from the US group (successful procedure rate 97.5%) because of ineffective post-ultrasonic coagulation of venous paravaginal varices (RALVH procedure) and of vena ovarica varices (LAVH, BSO procedure). The UltraCision was effective in all cases of lymphadenectomy. Successful procedure rate of the ELC operative technique was 100%. There were no statistically significant differences between the groups with regard to operation time, blood loss, hospital stay, and complications. There was a significant difference (P<0.001) in the number of lymph nodes harvested: a mean of 18.1 in the US group and 13.7 in the ELC group. We think that the difference was influenced by an increase in experience with laparoscopic lymph node dissection. The UltraCision operative technique ensures efficient dissection, coagulation, cutting, and grasping for LASS in women with cervical and endometrial cancer.  相似文献   
23.
Behavioral studies have shown that picture-plane inversion impacts face and object recognition differently, thereby suggesting face-specific processing mechanisms in the human brain. Here we used event-related potentials to investigate the time course of this behavioral inversion effect in both faces and novel objects. ERPs were recorded for 14 subjects presented with upright and inverted visual categories, including human faces and novel objects (Greebles). A N170 was obtained for all categories of stimuli, including Greebles. However, only inverted faces delayed and enhanced N170 (bilaterally). These observations indicate that the N170 is not specific to faces, as has been previously claimed. In addition, the amplitude difference between faces and objects does not reflect face-specific mechanisms since it can be smaller than between non-face object categories. There do exist some early differences in the time-course of categorization for faces and non-faces across inversion. This may be attributed either to stimulus category per se (e.g. face-specific mechanisms) or to differences in the level of expertise between these categories.  相似文献   
24.
BACKGROUND: Capecitabine is active against anthracycline- and taxane-pretreated metastatic breast cancer. Post-marketing use of capecitabine at the FDA-approved dose (2500 mg/m2/day) leads to unacceptable toxicity in many patients. Dose reductions anecdotally improve tolerability without compromising efficacy. This retrospective analysis was designed to verify these anecdotal reports. Patients and methods: We retrospectively reviewed the records of 141 consecutive patients with metastatic breast cancer identified from pharmacy records as receiving capecitabine outside of a clinical trial between May 1998 and February 1999. Responses were defined as clinical improvement (ID), stabilization of disease (SD) for 6 weeks or longer, or progression (PD). Patients were grouped according to the starting dose level of capecitabine: A=2500+/-5% (dose range 2385-2560) mg/m2/day; B=2250+/-5% (range 2130-2350) mg/m2/day; C < or = 2000+5% (range 1000-2100) mg/m2/day. We also reviewed the safety profile of capecitabine at these doses and performed a safety review of capecitabine in phase II and III metastatic breast and colorectal cancer trials. RESULTS: Clinical data were available for 113 patients (105 for response, 106 for toxicity). The median age was 52.5 years and the mean number of prior metastatic chemotherapy regimens was 2 (range 0-7). The mean capecitabine starting dose was 2220 mg/m2/day and the median number of cycles administered was 4 (range 1-19). The mean tolerated dose was 2040 mg/m2/day (range 960-2670). Grade 3/4 toxic effects at dose levels A, B and C, respectively, included palmar-plantar erythrodysesthesia (33%, 63%, 20%), diarrhea (13%, 12%, 3%), stomatitis (8%, 0%, 3%), and nausea/vomiting (4%, 6%, 5%). Forty per cent of all patients required capecitabine dose reductions; fewer patients treated with 2000 mg/m2/day required dose modification (28%). Five per cent of the patients required discontinuation of capecitabine owing to toxicity. Patients started at the lowest doses of capecitabine did not have poorer response rates or shorter time to progression. CONCLUSIONS: This retrospective analysis supports a starting dose of 2000 mg/m2/day because of its superior therapeutic index; however, patients may still have toxic effects and individualization of dosing is necessary. A phase III, multicenter, randomized study to establish the safety and efficacy of different doses of capecitabine is urgently needed.  相似文献   
25.
26.
The organophosphate flame retardants tris(2-butoxyethyl) phosphate (TBOEP) and triethyl phosphate (TEP) are used in a wide range of applications to suppress or delay the ignition and spread of fire. Both compounds have been detected in the environment and TBOEP was recently measured in free-living avian species. In this study, TBOEP and TEP were injected into the air cell of chicken embryos at concentrations ranging from 0 to 45,400 ng/g and 0 to 241,500 ng/g egg, respectively. Pipping success, development, hepatic mRNA expression of 9 target genes, thyroid hormone levels, and circulating bile acid concentrations were determined. Exposure to the highest doses of TBOEP and TEP resulted in negligible detection of the parent compounds in embryonic contents at pipping indicating their complete metabolic degradation. TBOEP exposure had limited effects on chicken embryos, with the exception of hepatic CYP3A37 mRNA induction. TEP exposure decreased pipping success to 68%, altered growth, increased liver somatic index (LSI) and plasma bile acids, and modulated genes associated with xenobiotic and lipid metabolism and the thyroid hormone pathway. Plasma thyroxine levels were decreased at all TEP doses, including an environmentally-relevant concentration (8 ng/g), and gallbladder hypotrophy was evident at ≥ 43,200 ng/g. Tarsus length and circulating thyroxine concentration emerged as potential phenotypic anchors for the modulation of transthyretin mRNA. The increase in plasma bile acids and LSI, gallbladder hypotrophy, and discoloration of liver tissue represented potential phenotypic outcomes associated with modulation of hepatic genes involved with xenobiotic and lipid metabolism.  相似文献   
27.
We describe four children with severe supraglottic infections caused by group A beta-hemolytic streptococci. In each case the clinical presentation suggested Hemophilus influenzae epiglottitis. In only one patient was there significant involvement of the epiglottis, whereas all had striking inflammation of the aryepiglottic folds. Group A beta-hemolytic streptococcus was isolated in blood cultures in two patients and from the supraglottic area and trachea in two others. Fever persisted for 6 to 22 days, and tracheal intubation was necessary for 2 to 16 days, despite appropriate antibiotic therapy. The evolution of streptococcal supraglottitis may be protracted, and it must be managed accordingly.  相似文献   
28.
29.

Introduction

The impact of the dose and fractionation of thoracic radiotherapy on the risk of developing brain metastasis (BM) has not been evaluated prospectively in limited stage SCLC patients receiving prophylactic cerebral irradiation (PCI).

Methods

Data from patients treated with PCI from the CONVERT trial were analyzed.

Results

Four hundred forty-nine of 547 patients (82%) received PCI after completion of chemoradiotherapy. Baseline brain imaging consisted of computed tomographic scans in 356 of 449 patients (79%) and magnetic resonance imaging in 83 of 449 (18%) patients. PCI was delivered to 220 of 273 participants (81%) in the twice-daily (BD) group and 229 of 270 in the once-daily (OD) group (85%; p = 0.49). Total median PCI dose was 25 Gy in both the BD and OD groups (p = 0.74). In patients who received PCI, 75 (17%) developed BM (35 [8%] in OD and 40 [9%] in BD) and 173 (39%) other extracranial progression. In the univariate analysis, gross tumor volume (GTV) was associated with an increased risk of BM (p = 0.007) or other radiological progression events (p = 0.006), whereas in a multivariate analysis both thoracic GTV (tGTV) and ECOG performance score were associated with either progression type. The median overall survival (OS) of patients treated with PCI was 29 months. In the univariate analysis of OS, PCI timing from end of chemotherapy, weight loss of more than 10%, and tGTV were prognostic factors associated with OS. In the multivariate analysis, only tGTV was associated with OS. Delay between end of chemotherapy and PCI was not associated with OS.

Conclusions

Patients receiving OD or BD thoracic radiotherapy have the same risk of developing BM. Larger tumors are associated with a higher risk of BM.  相似文献   
30.
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