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81.
Optimal treatment allocation for placebo‐treatment comparisons in trials with discrete‐time survival endpoints 下载免费PDF全文
In many randomized controlled trials, treatment groups are of equal size, but this is not necessarily the best choice. This paper provides a methodology to calculate optimal treatment allocations for longitudinal trials when we wish to compare multiple treatment groups with a placebo group, and the comparisons may have unequal importance. The focus is on trials with a survival endpoint measured in discrete time. We assume the underlying survival process is Weibull and show that values for the parameters in the Weibull distribution have an impact on the optimal treatment allocation scheme in an interesting way. Additionally, we incorporate different cost considerations at the subject and measurement levels and determine the optimal number of time periods. We also show that when many events occur at the beginning of the trial, fewer time periods are more efficient. As an application, we revisit a risperidone maintenance treatment trial in schizophrenia and use our proposed methodology to redesign it and compare merits of our optimal design. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
82.
Purpose
To investigate the effects of laser suture lysis (LSL) on filtration openings after trabeculectomy.Methods
Prospective study analyzing the changes in the location and width of filtration openings, fluid cavity height, total bleb height, bleb wall thickness, and bleb wall intensity before and after LSL using three-dimensional anterior segment optical coherence tomography (3D AS-OCT).Results
Fourteen patients had clear scleral flap image analysis. As five patients underwent LSL twice and two patients underwent LSL thrice, 23 comparison studies were possible. After LSL the intraocular pressure (IOP) decreased (P=0.0015) from 20.5±5.3 to 14.9±6.4 mm Hg, and the fluid cavity height increased significantly from 0.2±0.2 mm to 0.3±0.1 mm (P=0.0094). Other bleb parameters were not significantly different when comparing before and after LSL. When the IOP reduction ratio was >25% following LSL, the width of the filtration openings on the LSL side, the total bleb height, and the fluid cavity height increased (P=0.0273, 0.0342, and 0.0024, respectively). In multiple regression analysis the changes in fluid cavity height, the wall thickness, the wall intensity, and the width of the filtration opening were positively associated with the IOP reduction rate (P=0.0428, 0.0226, 0.0420, and 0.0356, respectively).Conclusions
3D AS-OCT allowed a detailed examination of the internal morphology of filtration blebs and openings before and after LSL. The changes in the internal morphology were closely associated with the success of LSL to decrease IOP. 相似文献83.
Chung YS Chung YW Moon SY Yoon SM Kim MJ Kim KO Park CH Hahn T Yoo KS Park SH Kim JH Park CK 《World journal of gastroenterology : WJG》2008,14(6):948-950
Foreign bodies in the colon are encountered with increasing frequency, but only sporadic reports concerning their management have appeared in the literature. While most ingested foreign bodies usually pass through the gastrointestinal tract uneventfully, sharp foreign bodies such as toothpicks infrequently cause intestinal perforation and may even result in death. We report our experience with a patient with a sigmoid colon pseudodiverticulum formation, a complication of accidental ingestion of a toothpick that was diagnosed and successfully managed colonoscopically. 相似文献
84.
Kee F Young IS Poirier O McMaster D McCrum E McGeough J Patterson CC Dallongeville J Cambien F Evans AE 《Atherosclerosis》2000,153(1):119-128
To assess whether there is a differential hypocholesterolemic response to weight loss for subjects carrying polymorphisms of the apolipoprotein B and other genes. A before and after comparison of lipid parameters following a calorie controlled diet for an intervention period of 12 weeks. A lipid clinic based in a large teaching hospital. The difference in slope coefficients relating the percentage change in lipid parameters to the change in body weight (adjusted for age, gender and initial body mass index (BMI)), for genotype subgroups defined by polymorphisms of the 5'VNTR apoB gene, two mutations of the LPL gene and ApoE. One hundred and forty six subjects completed the intervention diet. While, on average, the intervention was successful (mean weight loss 3.9%), there was no statistically significant difference in the slope coefficients relating lipid change to weight loss for most of the genotypes tested. The slope difference for long versus short 5'VNTR alleles of the apoB gene was 0.445 (-1.307, 2.198) for apolipoprotein B and -0. 104 (-1.486, 1.278) for total cholesterol. However, subjects carrying at least one varepsilon4 allele were significantly hypo-responsive to weight loss, difference in slope coefficients -1.087 (-2.09, -0.084) and -1.320 (-2.589, 0.051) for total cholesterol and apoB, respectively. Although, this study is one of the largest of its kind, it has not replicated the findings of other smaller studies. These findings do not provide support for the use of genotype-targeted dietary advice in routine practice. 相似文献
85.
Endoscopic detection of early upper GI cancers 总被引:3,自引:0,他引:3
The detection of early-stage neoplastic lesions in the upper GI tract is associated with improved survival and the potential for complete endoscopic resection that is minimally invasive and less morbid than surgery. Despite technological advances in standard white-light endoscopy, the ability of the endoscopist to reliably detect dysplastic and early cancerous changes in the upper GI tract remains limited. In conditions such as Barrett's oesophagus, practice guidelines recommend periodic endoscopic surveillance with multiple biopsies, a methodology that is hindered by random sampling error, inconsistent histopathological interpretation, and delay in diagnosis. Early detection may be enhanced by several promising diagnostic modalities such as chromoendoscopy, magnification endoscopy, and optical spectroscopic/imaging techniques, as these modalities offer the potential to identify in real-time lesions that are inconspicuous under conventional endoscopy. The combination of novel diagnostic techniques and local endoscopic therapies will provide the endoscopist with much needed tools that can considerably enhance the detection and management of early stage lesions in the upper GI tract. 相似文献
86.
Hae Geun Song Kyo-Sang Yoo Na Rae Ju Jin Chul Park Jae One Jung Woon Geon Shin Joon Ho Moon Jong Pyo Kim Kyoung Oh Kim Cheol Hee Park Taeho Hahn Sang Hoon Park Jong Hyeok Kim In Jae Lee Soo Kee Min Choong Kee Park 《Taehan Sohwagi Hakhoe chi》2006,48(2):132-136
Adenosquamous carcinoma of the papilla of Vater is a rare tumor and only a few cases have been reported so far. Here, we report a case of adenosquamous carcinoma in a 76-year-old male who presented with jaundice and right upper quadrant abdominal pain. Ultrasonography and enhanced abdominal CT scans showed dilated common bile duct (CBD) and intrahepatic bile duct (IHD) with a suspicious obstructing mass in distal CBD. On endoscopy, obstructing and ulcerated mass was noted on the papilla of Vater. Histopathological inspection of the biopsied specimens from mass showed adenosquamous cell carcinoma of the papilla of Vater. Since the patient refused operation, we inserted a self-expandable metallic stent in distal CBD. This is the first case report on adenosquamous carcinoma of the papilla of Vater in Korea. 相似文献
87.
BACKGROUND AND AIMS: The (13)C-urea breath test ((13)C-UBT) is a reliable non-invasive method of diagnosing Helicobacter pylori infection in adults and children. However, only a few validation studies have been performed on the (13)C-UBT in very young children. The purpose of the present study was to evaluate the diagnostic accuracy of the (13)C-UBT according to age, and to determine the optimal cut-off value in children. METHODS: A total of 307 (13)C-UBT were performed in 274 children. All were compared with the results of endoscopic biopsy-based methods to confirm H. pylori infection. Seventy-five milligrams of (13)C-urea was ingested without a test meal. Two breath samples were collected at 0 and 30 min. The optimal cut-off value of the (13)C-UBT was assessed by determining the sensitivity, specificity, false negative, and false positive results, at cut-off values ranging from 2.0 to 10.0 per thousand. RESULTS: The delta over baseline (DOB) values of the (13)C-UBT showed a significant negative correlation with age in both the H. pylori-positive group (r = -0.309; P = 0.005) and the H. pylori-negative group (r = -0.162; P = 0.015). High false positive results and low specificity were noted in children aged 6 years or less compared with children older than 6 years at a cut-off value of 4.0 per thousand (false positives; 8.3%vs 0.85%, specificity; 89.8%vs 98.8%). After adjusting the cut-off value, the optimal cut-off values were found to be 4.0 per thousand in children older than 6 years and 7.0 per thousand in children aged 6 years or less. CONCLUSIONS: The cut-off value of the (13)C-UBT recommended regardless of age must be adjusted in preschool children to reduce the false positive results. 相似文献
88.
Hang Lak Lee Joo Hyun Sohn Jin Bae Kim Dong Soo Han Yong Chul Jeon Joon Soo Hahm Dong Hoo Lee Chun Suk Kee Yong Wook Park 《Taehan Sohwagi Hakhoe chi》2005,46(3):233-236
Leiomyosarcoma is an uncommon tumor which arises from various sites including uterus, stomach, retroperitoneum, superficial soft tissues, bladder, kidney, and lung. Primary hepatic leiomyosarcoma is a very rare tumor and fewer than 70 cases of primary hepatic leiomyosarcoma have been reported since the first publication in Japan. And there was only one case report of cutaneous metastasis from hepatic leiomyosarcoma. We recently experienced a case of primary hepatic leiomyosarcoma presenting as subcutaneous palpable mass. Herein we report this case with a review of literatures. 相似文献
89.
Lee CK Badros A Barlogie B Morris C Zangari M Fassas A van Rhee F Cottler-Fox M Jacobson J Thertulien R Muwalla F Mazher S Anaissie E Tricot G 《Experimental hematology》2003,31(1):73-80
OBJECTIVES: The aim of this study was to identify prognostic factors for outcome of high-risk patients with multiple myeloma after allogeneic transplantation prepared by reduced intensity conditioning (RIC). MATERIALS AND METHODS: Data from 45 consecutive patients (median age 52 years, range 38-68), who received grafts from a sibling (n = 34) or unrelated donor (n = 11) were analyzed. Fourteen patients received an RIC allotransplant while chemosensitive (>/=partial remission [PR]), whereas 31 chemoresistant patients (相似文献
90.
Kim TY Kim WB Song JY Rhee YS Gong G Cho YM Kim SY Kim SC Hong SJ Shong YK 《Clinical endocrinology》2005,63(5):588-593
BACKGROUND: The BRAF(V600E) mutation, the most common genetic alteration reported in papillary thyroid carcinoma, has been associated with poor prognostic factors. AIM: To determine whether the presence of the BRAF(V600E) mutation is associated with poor prognosis in Korean patients with conventional papillary thyroid microcarcinoma (micro-PTC). PATIENTS AND METHODS: DNA was extracted from paraffin-embedded thyroid tumour specimens taken from 60 patients with conventional micro-PTC, as well as from nine patients with follicular variant papillary carcinoma, six with nodular hyperplasia, four with follicular carcinoma (including one with Hürthle cell carcinoma), four with follicular adenoma (including two with Hürthle cell adenoma) and one each with medullary carcinoma, poorly differentiated carcinoma and anaplastic carcinoma. The presence of the BRAF(V600E) mutation was determined by polymerase chain reaction (PCR) amplification of exon 15 followed by direct sequencing. RESULTS: The BRAF(V600E) mutation was detected in tumour samples from 31 of 60 conventional micro-PTC patients (52%), but was not detected in patients with other types of thyroid tumours. The age distribution, tumour size, extrathyroid extension, multifocality and staging did not differ significantly between patients with and without the BRAF(V600E) mutation. CONCLUSION: In Korean patients with conventional micro-PTC, the presence of the BRAF(V600E) mutation was not significantly associated with prognostic factors. 相似文献