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   2847篇
  免费   223篇
  国内免费   18篇
耳鼻咽喉   11篇
儿科学   111篇
妇产科学   56篇
基础医学   348篇
口腔科学   74篇
临床医学   323篇
内科学   880篇
皮肤病学   27篇
神经病学   230篇
特种医学   55篇
外科学   364篇
综合类   30篇
预防医学   235篇
眼科学   30篇
药学   144篇
中国医学   10篇
肿瘤学   160篇
  2023年   17篇
  2022年   38篇
  2021年   81篇
  2020年   49篇
  2019年   86篇
  2018年   89篇
  2017年   56篇
  2016年   58篇
  2015年   68篇
  2014年   123篇
  2013年   155篇
  2012年   211篇
  2011年   236篇
  2010年   122篇
  2009年   111篇
  2008年   180篇
  2007年   216篇
  2006年   165篇
  2005年   174篇
  2004年   150篇
  2003年   128篇
  2002年   136篇
  2001年   31篇
  2000年   19篇
  1999年   22篇
  1998年   32篇
  1997年   34篇
  1996年   18篇
  1995年   9篇
  1994年   9篇
  1993年   14篇
  1992年   16篇
  1991年   14篇
  1990年   10篇
  1989年   11篇
  1988年   7篇
  1987年   11篇
  1986年   16篇
  1985年   10篇
  1984年   9篇
  1983年   11篇
  1982年   12篇
  1981年   10篇
  1980年   15篇
  1979年   9篇
  1978年   10篇
  1977年   6篇
  1976年   7篇
  1975年   9篇
  1968年   6篇
排序方式: 共有3088条查询结果,搜索用时 15 毫秒
1.
2.
Abstract –  The aim of this study was to investigate mechano-sensory responses of injured and uninjured incisor teeth. Twenty-five children who had experienced dental trauma, together with age- and gender-matched controls, were studied prospectively. Touch thresholds of incisor teeth from both groups were determined using calibrated sets of von Frey hairs (force range 0.5–10.0 g in 0.5 g increments) using a forced choice staircase method. Forces were applied perpendicular to the buccal enamel surfaces along the midline, 2 mm from the incisal edge. Touch threshold was defined as the lowest force detected in three out of the five occasions. Following statistical analysis, P  < 0.05 was considered significant. At initial examination, the touch threshold values of 25 traumatised teeth were significantly greater than the untraumatised controls ( P  < 0.001), and these values approached those of the control teeth over 3–12 months ( P  > 0.05). Dental trauma was associated with increased touch thresholds in permanent incisor teeth, with recovery toward healthy control values usually occurring between 3–12 months.  相似文献   
3.
4.
Kollicoat IR, a new pharmaceutical excipient developed as a coating polymer for instant release tablets, was evaluated as a carrier in solid dispersions of Itraconazole. The solid dispersions were prepared by hot stage extrusion. Modulated temperature differential scanning calorimetry and X-ray powder diffraction were used to evaluate the miscibility of the drug and the carrier. The pharmaceutical performance was evaluated by dissolution experiments, performed in simulated gastric fluid without pepsin (SGF(sp)). In the X-ray diffractograms no Itraconazole peaks were visible; the polymer on the other hand appeared to be semi-crystalline. Moreover, its crystallinity increased during the extrusion process due to exposure to heat and shear forces. Modulated temperature differential scanning calorimetry analysis showed that the drug and the polymer formed a two phase system. Separate clusters of glassy Itraconazole were present for drug loads of 40% or higher, indicating further phase separation. Dissolution measurements demonstrated a significantly increased dissolution rate for the solid dispersions compared to physical mixtures. Interestingly the physical mixture made up of glassy Itraconazole and Kollicoat IR (20/80, w/w) showed a dissolution rate and maximum that was much higher than that of the physical mixture made up of crystalline Itraconazole and that of pure glassy Itraconazole. The results of this study show that Kollicoat IR is a promising excipient for the formulation of solid dispersions of Itraconazole prepared by hot stage extrusion.  相似文献   
5.
M LeFevre  H A Williamson  M Hector 《The Journal of family practice》1989,28(6):691-5; discussion 695-6
A study was undertaken to evaluate Coopland's obstetric risk index in a rural primary care setting. Information on 635 pregnant women cared for in a rural practice was collected prospectively. Adverse outcome was defined as perinatal death, birthweight less than 2500 g, 5-minute Apgar score less than 7, or newborn transferred to a level 2 or level 3 nursery. Forty-seven pregnancies (8.3%) had an adverse outcome. There was a clear relationship between risk score and probability of adverse outcome. Good sensitivity could be achieved only at the expense of a very high false-positive rate, however. The index can be used to identify a subgroup of women at relatively high risk for adverse outcome, but the majority of adverse outcomes will occur in women identified as low risk. The risk-scoring system in this population was no more effective than a policy that would refer all women with standard obstetric risk factors.  相似文献   
6.
The authors present the clinical case of a 31 year female with systemic vascular hypertension secondary to a 65 percent unilateral fibromuscular renal artery stenosis. The centellographic study demonstrated hypoperfusion on the right kidney and serious functional damage; the patient was subject to intraluminal renal angioplasty resulting in right renal arterial thrombosis, which was treated successfully with intra-arterial and intravenous streptokinase infusion. Following the thrombotic therapy, recanalization of the thrombosed artery and normal renal excretion of the contrast substance was observed.  相似文献   
7.
Percutaneous transvenous mitral commissurotomy was performed successfully via the transjugular approach in a patient with severe rheumatic mitral stenosis and obstruction of the inferior vena cava due to prior liver transplantation. This case demonstrates the advantage of the jugular approach in patients with difficult anatomy.  相似文献   
8.
Background: The purpose of this study was to evaluate the tumor characteristics and treatment associated with an improved overall survival in patients with adenocarcinoma of the small intestine. Methods: The records of all patients with primary adenocarcinoma of the small bowel seen between January 1971 and December 1991 were reviewed retrospectively. The study comprised 38 patients, 22 (58%) with duodenal tumors, 11 (29%) with jejunal tumors, and five (13%) with ileal tumors. Results: Although not statistically significant, the patients with duodenal adenocarcinoma lived longer than the patients with jejunal or ileal lesions (p=0.77). The overall survival was 23% and seemed to correlate best with absence of lymph node metastases (p=0.04) and pancreaticoduodenectomy for localized duodenal tumors (p=0.04). The patient's age, duration of symptoms, disease-free interval, tumor location, type of recurrence, and histologic grade did not significantly influence survival. Conclusions: The lethality of small-intestinal adenocarcinoma appears to be related to a delay in diagnosis and treatment. When a definitive surgical procedure is performed before lymph node metastases appear, the patient's chance for long-term survival is greatly improved.Presented at the 46th Annual Cancer Symposium of The Society of Surgical Oncology, Los Angeles, California, March 18–21, 1993.  相似文献   
9.
Polyethylene terephthalate (PET) tubes have several advantages over glass tubes: they are unbreakable, lighter and more easily disposed of. Despite a steady increase in their use and an expansion of the range of available tubes, few studies validating their use have been published in the literature. This paper describes the various studies that have been performed to compare VENOJECT glass, VENOSAFE PET and VENOSAFE PET/heparin tubes for the assay of a panel of analytes in routine clinical chemistry, immunochemistry, hormone and tumor marker analysis and trace metal determination. These studies demonstrate that VENOSAFE PET tubes are a suitable alternative to glass tubes.  相似文献   
10.
BACKGROUND: Many studies have shown differences in cardiac care by racial/ethnic groups without accounting for institutional factors at the location of care. OBJECTIVE: Exploratory analysis of the effect of hospital funding status (public vs private) on emergency department (ED) triage decision making for patients with symptoms suggestive of acute coronary syndromes (ACSs) and on the likelihood of ED discharge for patients with confirmed ACS. STUDY DESIGN AND SETTING: Secondary analysis of data from a randomized controlled trial of 10,659 ED patients with possible ACS in five urban academic public and five private hospitals. The main outcome measures were the sensitivity and specificity of hospital admission for the presence of ACS at public and private hospitals and the adjusted odds of a patient with ACS not being hospitalized at public versus private hospitals. RESULTS: Of 10,659 ED patients, 1,856 had confirmed ACS. For patients with suspected ACS, triage decisions at private hospitals were considerably more sensitive (99 vs 96%; p<.001) but less specific (30 vs 48%; p<.001) than at public hospitals. The difference between hospital types persisted after adjustment for multiple patient-level and hospital-level characteristics. CONCLUSION: Significant differences in triage for patients with suspected ACS exist between public and private hospital EDs, even after adjustment for multiple patient demographic, clinical, and institutional factors. Further studies are needed to clarify the causes of the differences.  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