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   23868篇
  免费   2029篇
  国内免费   766篇
耳鼻咽喉   231篇
儿科学   293篇
妇产科学   258篇
基础医学   3403篇
口腔科学   410篇
临床医学   2668篇
内科学   4207篇
皮肤病学   491篇
神经病学   1856篇
特种医学   1091篇
外国民族医学   5篇
外科学   3369篇
综合类   1882篇
现状与发展   2篇
一般理论   9篇
预防医学   1477篇
眼科学   563篇
药学   2028篇
  3篇
中国医学   725篇
肿瘤学   1692篇
  2024年   32篇
  2023年   231篇
  2022年   557篇
  2021年   1032篇
  2020年   650篇
  2019年   700篇
  2018年   799篇
  2017年   625篇
  2016年   682篇
  2015年   956篇
  2014年   1219篇
  2013年   1257篇
  2012年   1807篇
  2011年   1963篇
  2010年   1170篇
  2009年   960篇
  2008年   1406篇
  2007年   1363篇
  2006年   1309篇
  2005年   1306篇
  2004年   1018篇
  2003年   1078篇
  2002年   965篇
  2001年   441篇
  2000年   347篇
  1999年   314篇
  1998年   264篇
  1997年   214篇
  1996年   179篇
  1995年   159篇
  1994年   141篇
  1993年   105篇
  1992年   107篇
  1991年   107篇
  1990年   85篇
  1989年   93篇
  1988年   73篇
  1987年   73篇
  1986年   62篇
  1985年   53篇
  1984年   58篇
  1983年   49篇
  1982年   55篇
  1981年   53篇
  1980年   56篇
  1979年   46篇
  1978年   38篇
  1977年   41篇
  1976年   36篇
  1975年   33篇
排序方式: 共有10000条查询结果,搜索用时 421 毫秒
901.
BackgroundAccording to the World Health Organization, alcohol use disorder (AUD) is one of the leading mental health disorders in the United States. As the utilization of primary total shoulder arthroplasties (TSAs) continues to increase nationwide for the treatment of glenohumeral osteoarthritis (OA), studies evaluating the association of AUD with outcomes after primary TSA are warranted. Therefore, the aim of this study was to determine whether patients who undergo TSA and who have AUD have higher in-hospital lengths of stay (LOS), medical complications, and health care expenditures.MethodsThe Parts A and B 100% Medicare Claims Database were queried to identify patients who underwent primary TSA for glenohumeral OA and have AUD from January 1, 2005 to March 31, 2014. Patients were 1:5 ratio matched to a comparison cohort by age, sex, and various comorbid conditions. The query yielded 32,846 patients in the study (n = 5479) and comparison (n = 27,367) cohorts. The variables of interest include comparison of in-hospital LOS, 90-day medical complications, and day of surgery and 90-day health care costs. Welch’s t-tests were used to compare LOS, whereas multivariate logistic regression analyses were used to calculate the odds ratio (OR) of AUD on complications. A P value less than 0.001 was considered to be statistically significant.ResultsPatients with AUD had significantly longer in-hospital LOS (4 vs. 2 days, P < .0001), in addition to higher rates and odds of 90-day complications (30.44% vs. 7.94%; OR: 1.85, P < .0001) such as surgical site infections (1.15 vs. 0.24%; OR: 2.33, P < .0001), cerebrovascular accidents (5.06 vs. 1.23%; OR: 2.16, P < .0001), respiratory failures (5.79 vs. 1.52%; OR: 2.02, P < .0001), myocardial infarctions (1.53 vs. 0.43%; OR: 2.01, P < .0001), acute kidney injuries (6.55 vs. 1.34%; OR: 1.89, P < .0001), and other complications. In addition, patients in the study group incurred significantly higher day of surgery ($12,160.60 vs. $11,308.48, P < .0001) and 90-day episode of care costs ($14,493.13 vs. $13,087.55, P < .0001).ConclusionAs the prevalence of AUD continues to increase nationwide, understanding the association of AUD with outcomes after primary TSA for the treatment of glenohumeral OA is necessary. The current investigation is important as health care professionals and orthopedists can use this information to adequately educate patients on potential complications which may occur after their procedure.  相似文献   
902.
903.
An ideal animal model is a prerequisite for the basic research of uterus transplantation. This study aimed to develop a new cervical ectopic uterus transplantation mice model, which was established by vascular anastomosis of the right common iliac artery and vein of the donor with the right common carotid artery and external jugular vein of the recipient, respectively, using the cuff method. The survival status of the transplanted uterus was assessed by macroscopic observation and histological examination after surgery, and the function of the graft uterus was tested by verifying whether the pregnancy is possible. A total of 40 transplants were performed, of which only 1 failed due to donor hemorrhage. After 26 transplants, the total operation time reduced to 52.4 ± 3.8 minutes, of which the total ischemia time took 6.6 ± 1.1 minutes. Sixty days after transplantation, all the graft uteri had a good blood supply and spontaneous contraction. The histology showed no significant difference between the transplanted uterus and the native. Embryo transfer experiments have proven that the transplanted uterus has uterine function. In conclusion, this new model is an effective and simple mice model for the studies of the scientific issues related to uterus transplantation.  相似文献   
904.
905.
Postoperative bleeding is the most frequent serious complications after vacuum‐assisted breast biopsy (VABB). The aim of this study was to evaluate the clinical effect of using urinary balloon catheter to prevent postoperative bleeding after ultrasound‐guided VABB. From May 2016 to June 2018, 324 patients who underwent ultrasound‐guided VABB were randomized into the study group and control group. In the study group, an urinary balloon catheter was inserted into the excision cavity to prevent bleeding and hematoma. In the control group, compression with thorax pressure bandage was used for hemostasis. Postoperative subcutaneous ecchymosis and hematoma were recorded and compared between the two groups. The rates of postoperative ecchymosis and hematoma in the study group were significantly lower than that in the control group (5.6% vs 13.0%, P < .05; 8.0% vs 20.4%, P < .05). Among patients with lesions ≤1.5 cm, the rates of postoperative ecchymosis and hematoma were 2.9% and 4.3% in the study group, 6.5% and 11.7% in the control group, but there was no statistically significant difference between the two groups (P > .05). Among patients with lesions >1.5 cm, the rates of postoperative ecchymosis and hematoma in the study group were significantly lower than that in the control group (7.6% vs 18.8%, P < .05; 10.9% vs 28.2%, P < .05). Hemostasis with balloon urinary catheter is a safe and effective method to prevent postoperative bleeding after VABB.  相似文献   
906.
Porcine respiratory and reproductive syndrome virus (PRRSV) causes an economically important disease affecting commercial pork production worldwide. NADC34‐like PRRSV has had a strong impact on the U.S. and Peruvian pig industries in recent years and also emerged in northeastern China in 2017. However, the endemic status of NADC34‐like PRRSV in China is unclear. In this study, we examined 650 tissue samples collected from 16 Provinces in China from 2018 to 2019. Six NADC34‐like PRRSV strains were detected in samples from three Provinces, and the complete genomes of four of these strains were sequenced. Phylogenetic analysis showed that these novel PRRSV strains belong to sublineage 1.5 (or NADC34‐like PRRSV), forming two groups in China. Sequence alignment suggested that these novel strains share the same 100‐aa deletion in the Nsp2 protein that was identified in IA/2014/NADC34 isolated from the United States in 2014. Recombination analysis revealed that five of eight complete genome sequences are derived from recombination between IA/2014/NADC34 and ISU30 or NADC30. The number and distribution of NADC34‐like PRRSVs is increasing in China. Importantly, compared with the currently endemic strain NADC30‐like PRRSV, NADC34‐like PRRSV has the potential to be an endemic strain in China. This study will help us understand the epidemic status of NADC34‐like PRRSV in China and provide data for further monitoring this type of PRRSV in China.  相似文献   
907.
As an emerging disease, the porcine epidemic diarrhoea virus has caused substantial economic losses to the pork industry in Mexico, leading to piglet mortality rates of up to 100%. For detection, sequencing and genetic characterization of the virus, 68 samples of one‐week‐old piglets from pork farms in 17 states of Mexico were analysed. In total, 53 samples were positive by real‐time RT‐PCR, confirming the presence of the virus in 15 states. Twenty‐eight samples from 10 states were amplified by endpoint RT‐PCR, and 20 sequences of the spike gene were obtained. A phylogenetic analysis based on the spike gene demonstrated that all Mexican strains are in Group II and are classified as non‐Indel‐S emerging variants. Three strains showed amino acid insertions: PEDv/MEX/GTO/LI‐DMZC15/2015 and PEDv/MEX/QRO/LI‐DMZC45/2016 showed one amino acid insertion (424Y425 and 447D448, respectively), and PEDv/MEX/QRO/LI‐DMZC49/2019 showed one and two amino acid insertions (422C423 and 537SQ538), with the second insertion in the COE region. These results provide evidence of the prevalence of emerging, non‐Indel‐S strains of the virus are currently circulating in Mexico during 2016–2018, when three of which have amino acid insertions: PEDv/MEX/GTO/IN‐DMZC15/2015 and PEDv/MEX/QRO/IN‐DMZC45/2016 have one amino acid insertion each (424Y425 and 447D448, respectively), and PEDv/MEX/QRO/IN‐DMZC49/2019 has one (422C423) and two amino acid insertions (537SQ538), the latter being in the COE region, which could generate new antigenic variants.  相似文献   
908.
909.
Nonhealing wounds possess elevated numbers of pro‐inflammatory M1 macrophages, which fail to transition to anti‐inflammatory M2 phenotypes that promote healing. Hemoglobin (Hb) and haptoglobin (Hp) proteins, when complexed (Hb‐Hp), can elicit M2‐like macrophages through the heme oxygenase‐1 (HO‐1) pathway. Despite the fact that nonhealing wounds are chronically inflamed, previous studies have focused on non‐inflammatory systems, and do not thoroughly compare the effects of complexed vs individual proteins. We aimed to investigate the effect of Hb/Hp treatments on macrophage phenotype in an inflammatory, lipopolysaccharide (LPS)‐stimulated environment, similar to chronic wounds. Human M1 macrophages were cultured in vitro and stimulated with LPS. Concurrently, Hp, Hb, or Hb‐Hp complexes were delivered. The next day, 27 proteins related to inflammation were measured in the supernatants. Hp treatment decreased a majority of inflammatory factors, Hb increased many, and Hb‐Hp had intermediate trends, indicating that Hp attenuated overall inflammation to the greatest extent. From this data, Ingenuity Pathway Analysis software identified high motility group box 1 (HMGB1) as a key canonical pathway—strongly down‐regulated from Hp, strongly up‐regulated from Hb, and slightly activated from Hb‐Hp. HMGB1 measurements in macrophage supernatants confirmed this trend. In vivo results in diabetic mice with biopsy punch wounds demonstrated accelerated wound closure with Hp treatment, and delayed wound closure with Hb treatment. This work specifically studied Hb/Hp effects on macrophages in a highly inflammatory environment relevant to chronic wound healing. Results show that Hp—and not Hb‐Hp, which is known to be superior in noninflammatory conditions—reduces inflammation in LPS‐stimulated macrophages, and HMGB1 signaling is also implicated. Overall, Hp treatment on M1 macrophages in vitro reduced the inflammatory secretion profile, and also exhibited benefits in in silico and in vivo wound‐healing models.  相似文献   
910.
Background

Adjacent segment disease (ASDz) is a potential complication following lumbar spinal fusion. A common nomenclature based on etiology and ASDz type does not exist and is needed to assist with clinical prognostication, decision making, and management.

Questions/Purposes

The objective of this study was to develop an etiology-based classification system for ASDz following lumbar fusion.

Methods

We conducted a retrospective chart review of 65 consecutive patients who had undergone both a lumbar fusion performed by a single surgeon and a subsequent procedure for ASDz. We established an etiology-based classification system for lumbar ASDz with the following six categories: “degenerative” (degenerative disc disease or spondylosis), “neurologic” (disc herniation, stenosis), “instability” (spondylolisthesis, rotatory subluxation), “deformity” (scoliosis, kyphosis), “complex” (fracture, infection), or “combined.” Based on this scheme, we determined the rate of ASDz in each etiologic category.

Results

Of the 65 patients, 27 (41.5%) underwent surgery for neurogenic claudication or radiculopathy for adjacent-level stenosis or disc herniation and were classified as “neurologic.” Ten patients (15.4%) had progressive degenerative disc pathology at the adjacent level and were classified as “degenerative.” Ten patients (15.4%) had spondylolisthesis or instability and were classified as “instability,” and three patients (4.6%) required revision surgery for adjacent-level kyphosis or scoliosis and were classified as “deformity.” Fifteen patients (23.1%) had multiple diagnoses that included a combination of categories and were classified as “combined.”

Conclusion

This is the first study to propose an etiology-based classification scheme of ASDz following lumbar spine fusion. This simple classification system may allow for the grouping and standardization of patients with similar pathologies and thus for more specific pre-operative diagnoses, personalized treatments, and improved outcome analyses.

  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