全文获取类型
收费全文 | 164418篇 |
免费 | 9062篇 |
国内免费 | 323篇 |
专业分类
耳鼻咽喉 | 2292篇 |
儿科学 | 6412篇 |
妇产科学 | 4785篇 |
基础医学 | 22385篇 |
口腔科学 | 4076篇 |
临床医学 | 13000篇 |
内科学 | 31802篇 |
皮肤病学 | 4072篇 |
神经病学 | 13714篇 |
特种医学 | 7573篇 |
外国民族医学 | 38篇 |
外科学 | 26155篇 |
综合类 | 2183篇 |
一般理论 | 69篇 |
预防医学 | 9788篇 |
眼科学 | 4559篇 |
药学 | 10944篇 |
中国医学 | 391篇 |
肿瘤学 | 9565篇 |
出版年
2021年 | 1342篇 |
2019年 | 1417篇 |
2018年 | 1834篇 |
2017年 | 1541篇 |
2016年 | 1993篇 |
2015年 | 2256篇 |
2014年 | 3054篇 |
2013年 | 4382篇 |
2012年 | 6140篇 |
2011年 | 6396篇 |
2010年 | 3823篇 |
2009年 | 3623篇 |
2008年 | 6268篇 |
2007年 | 6596篇 |
2006年 | 6702篇 |
2005年 | 6749篇 |
2004年 | 6510篇 |
2003年 | 6277篇 |
2002年 | 6136篇 |
2001年 | 7610篇 |
2000年 | 7507篇 |
1999年 | 6478篇 |
1998年 | 2207篇 |
1997年 | 2022篇 |
1996年 | 1753篇 |
1995年 | 1601篇 |
1994年 | 1412篇 |
1993年 | 1408篇 |
1992年 | 4127篇 |
1991年 | 3909篇 |
1990年 | 3868篇 |
1989年 | 3669篇 |
1988年 | 3268篇 |
1987年 | 3197篇 |
1986年 | 3078篇 |
1985年 | 2911篇 |
1984年 | 2243篇 |
1983年 | 1884篇 |
1982年 | 1245篇 |
1981年 | 1211篇 |
1980年 | 1028篇 |
1979年 | 2045篇 |
1978年 | 1575篇 |
1977年 | 1306篇 |
1976年 | 1102篇 |
1975年 | 1355篇 |
1974年 | 1393篇 |
1973年 | 1346篇 |
1972年 | 1190篇 |
1971年 | 1077篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
101.
Diane C. Mitchell Author Vitae Frank R. LawrenceAuthor Vitae Terryl J. HartmanAuthor Vitae Julianne M. CurranAuthor Vitae 《Journal of the American Dietetic Association》2009,109(5):909-913
The US Department of Agriculture's MyPyramid guidelines introduced a near doubling of the dietary recommendations for vegetables. These recommendations target specific subgroups of vegetables, including dry beans and peas. Dry beans and peas provide an array of nutrients and phytochemicals that have been shown to have beneficial health effects, yet consumption levels in the United States are quite low. Few studies have examined the influence of legume consumption on nutrient intakes. Therefore, the purpose of this study was to assess nutrient and food group intakes of dry bean and pea consumers compared to nonconsumers. Dietary intake data from the 1999-2002 National Health and Nutrition Examination Survey for adults aged ≥19 years was used. Results show that on any given day only 7.9% of adults are consuming dry beans and peas; Mexican Americans or other Hispanics are more likely to be consumers than nonconsumers. Consuming approximately ½ c dry beans or peas resulted in higher intakes of fiber, protein, folate, zinc, iron, and magnesium with lower intakes of saturated fat and total fat. These data support the specific recommendation for dry beans and peas as part of the overall vegetable recommendation. Increased consumption of dry beans and peas—economical and nutrient-rich foods—could improve the diet quality of Americans. 相似文献
102.
103.
A. S. Mühlfeld M. Ketteler K. Schwamborn F. Eitner B. Schneider U. Gladziwa R. Knüchel J. Floege 《American journal of transplantation》2007,7(7):1865-1868
Sticky platelet syndrome (SPS) leads to hyperaggregabilty of platelets in response to physiologic stimuli. In this report we describe three patients with clinical symptoms of SPS after renal transplantation. The first patient developed an infarction of her transplant kidney with additional, subsequent renal microinfarctions. The second patient suffered multiple strokes and deep vein thrombosis with episodes of pulmonary embolism and ischemic bowel disease due to colonic microinfarctions. The third patient experienced a long episode of unexplained respiratory and graft dysfunction immediately after transplantation until therapy for SPS was initiated, at which point symptoms resolved quickly. Kidney transplant recipients with SPS may be at increased risk of developing thrombosis, given that most immunosuppressive drugs are known to induce either endothelial cell damage or augment platelet aggregation. All patients awaiting renal transplantation should be screened for a history of thrombosis and, if appropriate, tested for SPS. Affected patients should receive dose-adjusted acetylsalicylic acid. 相似文献
104.
105.
Presented in this work is a rare injury of a blunt abdominal trauma in a child. Besides a partial rupture of the kidney and a retro-/intraperitoneal haematoma, a further injury occurred from the accident: an initially clinically indetectable tear of the A. iliaca communis which was found intraoperatively and with systematic CT analysis. Traumatic blood vessel lesions of the abdominal aorta and in particular the iliac blood vessels are very rare in children. By such violent impact injuries, it is therefore vital to perform a clinical examination of the foot pulse, systematic analysis of radiology diagnostics, and intraoperative exploration. The growth phase should be considered for therapy of the blood vessels depending on the child's age group. As the long-term results of graft implants are practically unknown, if possible a primary suture or vein patch should be performed. 相似文献
106.
Ventilation imaging of the lung: Comparison of hyperpolarized helium-3 MR imaging with Xe-133 scintigraphy 总被引:1,自引:0,他引:1
Talissa A. Altes MD Patrice K. Rehm MD Frank Harrell PhD Michael Salerno PhD Thomas M. Daniel MD Eduard E. de Lange MD 《Academic radiology》2004,11(7):729-734
RATIONALE AND OBJECTIVES: To compare hyperpolarized helium-3 (HHe) magnetic resonance imaging (MRI) of the lung with standard Xe-133 lung ventilation scintigraphy. MATERIALS AND METHODS: We performed a retrospective review of 15 subjects who underwent HHe MRI and Xe-133 lung ventilation imaging. Coronal MRI sections were acquired after a single inhalation of HHe gas, and standard posterior planar lung ventilation scintigraphy was performed during continuous breathing of Xe-133 gas. The first breath scintigram of each patient was compared with a composite MR image composed of the sum of the individual MR images and with the individual helium-3 MR images. Ventilation defects on the two imaging modalities were compared for size, conspicuity, and concordance in presence and location. Assessment was done separately for each of four lung quadrants. RESULTS: Comparing the composite HHe MR images with Xe-133 scintigraphy, ventilation defect size, conspicuity and concordance were the same in 67% (40/60), 63% (38/60), and 62% (37/60) quadrants, respectively. Comparing the individual HHe MR image sections with the Xe-133 ventilation scan, there was concordance between the ventilation defects in 27% (16/60) of quadrants. More defects were identified on the individual HHe MR images in 62% (37/60) of quadrants. CONCLUSION: There was good agreement between composite HHe MR image and first breath Xe-133 scintigraphic images, supporting the widely held assumption that HHe MRI likely depicts first breath lung ventilation. 相似文献
107.
108.
109.
By oxygen concentration measurements (Oximeter Oxydig Dräger, Lübeck) in the EC 145 helicopter two oxygen transport and application systems were compared. The new liquid oxygen system (LOX) for the oxygen therapy was assessed in an application observation. For physical reasons fluid oxygen evaporates during the stand-by phase and an increased concentration (22.8% O2) in the exhaust valve of LOX arises. On the other hand a high oxygen concentration (22.7% O2) was measured in the operation mode of the conventional pressure flask gas system (GAS). No increased concentration could be measured within the helicopter cabin (HEMS, PAX) comparing both oxygen systems. For transport and application of oxygen with a very big reserve for the air dependent intensive transport the results show that LOX is a sure low pressure system (3.4 bar). 相似文献
110.
Objective To describe the clinical presentation of acute diverticulitis in an emergency department and to characterize the natural history of diverticulitis in the short perspective. Comparisons are made with an important differential diagnosis, nonspecific abdominal pain (NSAP). Method Patients admitted to our hospital with abdominal pain of up to 7 days’ duration were registered prospectively using a detailed schedule for history, symptoms and signs, from 1 February 1997 to 1 June 2000. Of 3349 patients initially included, 3073 (92%) were eligible for follow up after 1–3 years. Results Acute diverticulitis was the final diagnosis in 145 patients and NSAP in 1142 patients. The incidence of hospitalized patients with diverticulitis was 47 per year and 100 000 population, with a mean hospital stay of 3.3 days. Patients with diverticulitis, more frequently than NSAP, had a longer history and laboratory signs of inflammatory activity. Isolated left abdominal tenderness was more common in diverticulitis, whereas isolated right abdominal tenderness was more common in NSAP. Duration of symptoms on arrival was independent of age and was not correlated to C‐reactive protein, leucocytes or body temperature. Sensitivity of diverticulitis as primary diagnosis was 64% and specificity 97%. Corresponding figures for NSAP were 43% and 90% respectively. Age and gender did not influence diagnostic accuracy or risk of surgery. Conclusion Diverticulitis differs significantly from NSAP in clinical presentation and laboratory parameters. Sensitivity of primary diagnosis for diverticulitis and NSAP was low. 相似文献