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   9461篇
  免费   636篇
  国内免费   35篇
耳鼻咽喉   112篇
儿科学   245篇
妇产科学   115篇
基础医学   1283篇
口腔科学   354篇
临床医学   740篇
内科学   2488篇
皮肤病学   360篇
神经病学   955篇
特种医学   245篇
外科学   1372篇
综合类   54篇
一般理论   4篇
预防医学   622篇
眼科学   238篇
药学   450篇
中国医学   21篇
肿瘤学   474篇
  2024年   7篇
  2023年   126篇
  2022年   144篇
  2021年   489篇
  2020年   248篇
  2019年   381篇
  2018年   425篇
  2017年   222篇
  2016年   273篇
  2015年   340篇
  2014年   432篇
  2013年   553篇
  2012年   845篇
  2011年   851篇
  2010年   403篇
  2009年   364篇
  2008年   630篇
  2007年   599篇
  2006年   589篇
  2005年   494篇
  2004年   422篇
  2003年   348篇
  2002年   354篇
  2001年   59篇
  2000年   52篇
  1999年   52篇
  1998年   41篇
  1997年   57篇
  1996年   46篇
  1995年   38篇
  1994年   26篇
  1993年   14篇
  1992年   16篇
  1991年   15篇
  1990年   15篇
  1989年   16篇
  1988年   13篇
  1987年   5篇
  1986年   9篇
  1985年   8篇
  1984年   13篇
  1982年   16篇
  1981年   10篇
  1980年   12篇
  1977年   7篇
  1976年   7篇
  1975年   4篇
  1974年   7篇
  1973年   8篇
  1962年   4篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
81.
ObjectiveBuilding on the original taxonomy of hospital‐based health systems from 20 years ago, we develop a new taxonomy to inform emerging public policy and practice developments.Data SourcesThe 2016 American Hospital Association''s (AHA) Annual Survey; the 2016 IQVIA Healthcare Organizations and Systems (HCOS) database; and the 2017‐2018 National Survey of Healthcare Organizations and Systems (NSHOS).Study DesignCluster analysis of the 2016 AHA Annual Survey data to derive measures of differentiation, centralization, and integration to create categories or types of hospital‐based health systems.Data CollectionPrincipal components factor analysis with varimax rotation generating the factors used in the cluster algorithms.Principal FindingsAmong the four cluster types, 54% (N = 202) of systems are decentralized (−0.35) and relatively less differentiated (−0.37); 23% of systems (N = 85) are highly differentiated (1.28) but relatively decentralized (−0.29); 15% (N = 57) are highly centralized (2.04) and highly differentiated (0.65); and approximately 9 percent (N = 33) are least differentiated (−1.35) and most decentralized (−0.64). Despite differences in calculation, the Highly Centralized, Highly Differentiated System Cluster and the Undifferentiated, Decentralized System Cluster were similar to those identified 20 years ago. The other two system clusters contained similarities as well as differences from those 20 years ago. Overall, 82 percent of the systems remain relatively decentralized suggesting they operate largely as holding companies allowing autonomy to individual hospitals operating within the system.ConclusionsThe new taxonomy of hospital‐based health systems bears similarities as well as differences from 20 years ago. Important applications of the taxonomy for addressing current challenges facing the healthcare system, such as the transition to value‐based payment models, continued consolidation, and the growing importance of the social determinants of health, are highlighted.  相似文献   
82.
AimsTo validate a translated and culturally adapted version of the Morisky Medication Adherence Scale for use in Spanish population, and to examine the psychometric properties of this scale in patients with type 2 diabetes mellitus in Spain.DesignThis cross-sectional study was conducted in a single university hospital in Spain. Patients diagnosed with type 2 diabetes mellitus at least 1 year before inclusion, being treated with anti-diabetic medication were included.InterventionWe used the Spanish version of the scale to measure treatment adherence.Principal measurementsthree level categorical scale is broken down into low adherence (score of <6), medium adherence (score of 6 to <8) and high adherence (score of 8). To validate the questionnaire, we measured internal consistency through Cronbach's α, confirmed construct validity through an exploratory principal component analysis and assessed test–retest reliability.Results232 patients met the inclusion criteria. The Cronbach's α coefficient was 0.40 (95% CI 0.28–0.52). The exploratory principal component analysis showed three components. The intraclass correlation coefficient was 0.718 (95% CI 0.564–0.823).Conclusionsthe Spanish version of the Morisky Medication Adherence scale showed low internal consistency, the exploratory factor analysis identified three dimensions, and the test–retest reliability was acceptable, therefore, psychometric properties of MMAS-8 are not suitable for measuring medication adherence in type 2 diabetes mellitus patients from Spain.  相似文献   
83.
We report on 3 patients with Mulibrey nanism (MN), or Perheentupa syndrome: the first 2 sibs from Argentina and a new patient from Spain. All 3 patients had growth failure, short stature, abnormal pigmentary retinal changes, and a J-shaped sella turcica. These findings are considered major criteria of MN. Two had pericardial constriction, which is a frequent and lifethreatening abnormality in this syndrome. MN is a rare autosomal recessive condition. Reviewing the 39 patients described so far, we have classified the anomalies into the very frequent (present in more than 66%), frequent (in at least 25%), and not frequent. Identifying the anomalies specific to MN should help its early diagnosis and treatment. © 1995 Wiley-Liss, Inc.  相似文献   
84.
Background: Anterior chamber miotic solutions are widely used in ophthalmic surgery to induce pupillary contraction. We investigated whether the acetylcholine, carbachol, or mannitol present in perfusing solutions can affect corneal endothelial function. Methods: Freshly dissected deepithelized rabbit corneas were mounted in a Dikstein-Maurice chamber at 36 °C. The endothelial sides were perfused with six solutions: (A) 55 mM (1%) acetylcholine Cl plus modified balanced salts; (B) control for A, with acetylcholine Cl replaced by sucrose; (C) 0.55 mM (0.01%) carbachol Cl plus balanced salts; (D) balanced salts solution (BS; control for C); (E) 3% mannitol plus modified balanced salts; and (F) modified balanced salts (control for E, with mannitol replaced by sucrose). Corneal thickness was followed for 3 h in each experiment. The effect of solution E did not differ from that of solution F. Results: The carbachol-containing solution produced a small increase in corneal thickness compared to the control solution, while the acetylcholine-containing solution resulted in corneal thickness lower than that in control preparations. Conclusion: From these data, acetylcholine is harmless to the endothelium, and may actually stimulate its fluid pump mechanism. Carbachol, on the other hand, appears to have a detrimental effect.  相似文献   
85.
86.
Background: The complications of the gastric pouch in gastric bypass surgery are well known. Since the first report of this surgery 30 years ago, new technical aspects that make it safer and more effective have been implemented. Methods: As a modification of gastric bypass, the authors have performed 305 vertical banded gastroplasty-gastric bypass procedures. Two groups of patients underwent the procedure: Group I (n = 206) without a limb of jejunum interposed between the gastric pouch and the excluded stomach, and Group II (n = 99) with a limb of jejunum interposed between the pouch and the stomach. The results regarding excess weight loss and complications of the gastric pouch during the first year after surgery were compared. Results: Age, sex, initial weight, body mass index, and percentage of ideal weight were similar in both groups. Excess weight loss was also similar. The complications in Group I were 1 leak, 3 left subphrenic abscesses, 2 erosive gastritis with bleeding, 1 stenosis of the gastrojejunostomy, 1 perforated ulcer, and 4 marginal ulcers with bleeding. Two patients in Group II developed bleeding from the staple-line. Conclusions: These preliminary data suggest that complications of the gastric pouch can be reduced by interposing a limb of jejunum between the pouch and the excluded stomach. This is an early experience; long-term results are pending.  相似文献   
87.
PURPOSE: This study was conducted to determine the correlation between structural changes in the retinal nerve fiber layer (RNFL) and functional loss detected on short-wavelength automated perimetry (SWAP) in a population of patients with suspected glaucoma. METHODS: With a selection criteria of intraocular pressure (IOP) more than 21 mmHg and normal results of conventional automated perimetry, 49 eyes of 49 patients with ocular hypertension were enrolled in the study. The SWAP was performed with a modified Humphrey field analyzer, and visual field indexes (mean deviation [MD], corrected pattern standard deviation [CPSD]) were calculated. Semiquantitative RNFL scores were given separately to diffuse and localized defects of the RNFL. RESULTS: The MD increased significantly with higher diffuse and total RNFL scores, with good correlation coefficients. A weak correlation was found between CPSD and diffuse, total, and localized RNFL scores. CONCLUSION: Diffuse RNFL loss are associated with abnormalities in visual field indexes (MD), whereas focal structural damage showed no correlation with visual field loss.  相似文献   
88.
Both filtering surgery with Mitomycin-C and diode laser cyclophotocoagulation have proved to be effective alternatives in cases of glaucoma with poor surgical prognosis. The right eyes of 40 pigmented rabbits were randomly divided into 2 groups: Mitomycin-C group underwent filtering surgery with application of 0.4 mg/ml of Mitomycin-C whereas the diode laser (DL) group received 15 applications of 1.8 J (1800 mW. 1000 ms) distributed in 270°. Mean IOP showed statistical differences in two periods between days 3–13 and 45–60 — Mann-Whitney U test — with a higher IOP lowering in the DL group. The comparison of IOP survival curves (Log-Rank test) was not significant p = 0.070809. Ocular hypertension, hyphema and inflammatory signs were higher in the DL group, both in short and long term, but in terms of statistical significance only ocular hypertension showed differences p = 0.00011717 - Fisher exact test. Microscopic examination revealed patent sclerostomies in 60% of the MMC group eyes with different grades of fibroblastic proliferation. In the DL group we observed necrosis of the sclieral stroma and of the pigmented and unpigmented ciliary epithelium, with signs of thermal coagulation of the ciliary stroma and of the stromal vasculature. We must point out that the treatment with laser has proved to be more effective although both treatments showed very acceptable IOP lowering until 2 months after the surgery.  相似文献   
89.
PURPOSE: The purpose of this research was to identify promiscuous T-helper cell determinants (THd) from carcinoembryonic antigen (CEA) to be used to prime T-cell help for cancer therapy. CEA was selected because this antigen is expressed in an important variety of carcinomas. EXPERIMENTAL DESIGN: Potential promiscuous THd from CEA were predicted using available computer algorithms. Predicted peptides were synthesized and tested in binding experiments to different HLA-DR molecules. Binder peptides were then used to prime T-cell responses both in vitro and in vivo. RESULTS: Twenty 15-mer peptides from CEA were predicted to bind to different HLA-DR molecules. The promiscuous character of these peptides was demonstrated in binding experiments. Fifteen of 20 peptides tested were able to bind to HLA-DR4, but only CEA (625-639) was shown to be presented after processing of recombinant CEA. CEA (625-639) was also found to be presented by HLA-DR53. Moreover, immunization of HLA-DR4 transgenic mice with CEA (625-639) in conjunction with class I epitope OVA (257-264), induced a CTL response specific of OVA (257-264). CONCLUSIONS: CEA (625-639) might be a relevant promiscuous THd peptide for cancer therapy.  相似文献   
90.
PURPOSE: Neurofibromatosis type 1 (NF1) is characterized by systemic development of neurofibromas. Early clinical diagnosis can be ambiguous, and genetic diagnosis can be prohibitively difficult. Dysregulation of a number of growth factors has been suggested to be a mechanism of pathogenesis. This study was performed to assess the contribution of circulating growth factors for diffuse tumorigenesis and the diagnostic value of circulating growth factor identification in serum. EXPERIMENTAL DESIGN: The growth stimulation of neurofibroma-derived cells by serum from NF1 patients was tested, and serum growth factor levels in a cohort of NF1 patients (n = 39) between the ages of 7 and 70 years were analyzed. RESULTS: Concentrations of midkine (MK) and stem cell factor, but not epidermal growth factor, were substantially increased in serum of NF1 patients when compared with healthy controls. Within the NF1 group, MK levels increased dramatically at puberty from an average of 0.79 ng/mL in patients <18 years to 1.18 ng/mL in patients >18 years old. Stem cell factor and MK concentrations above a defined threshold in serum of NF1 patients are of diagnostic benefit for 96% of patients in the cohort tested. Furthermore, serum from NF1 patients enhanced proliferation of human neurofibroma-derived primary Schwann cells and endothelial cells substantially better than normal serum. CONCLUSIONS: Enhanced circulating growth factor levels contribute to diffuse tumorigenesis in NF1 and may provide the basis for molecular diagnosis.  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