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   2224篇
  免费   154篇
  国内免费   6篇
耳鼻咽喉   31篇
儿科学   34篇
妇产科学   64篇
基础医学   241篇
口腔科学   27篇
临床医学   215篇
内科学   408篇
皮肤病学   34篇
神经病学   160篇
特种医学   137篇
外科学   317篇
综合类   78篇
一般理论   2篇
预防医学   274篇
眼科学   23篇
药学   191篇
中国医学   9篇
肿瘤学   139篇
  2023年   12篇
  2022年   33篇
  2021年   71篇
  2020年   43篇
  2019年   72篇
  2018年   104篇
  2017年   62篇
  2016年   50篇
  2015年   58篇
  2014年   67篇
  2013年   97篇
  2012年   147篇
  2011年   161篇
  2010年   77篇
  2009年   68篇
  2008年   112篇
  2007年   103篇
  2006年   114篇
  2005年   127篇
  2004年   109篇
  2003年   102篇
  2002年   93篇
  2001年   39篇
  2000年   38篇
  1999年   35篇
  1998年   15篇
  1997年   12篇
  1996年   7篇
  1995年   13篇
  1994年   13篇
  1993年   12篇
  1992年   26篇
  1991年   21篇
  1990年   38篇
  1989年   22篇
  1988年   18篇
  1987年   16篇
  1986年   17篇
  1985年   7篇
  1984年   7篇
  1979年   12篇
  1978年   10篇
  1975年   9篇
  1974年   10篇
  1973年   11篇
  1972年   9篇
  1969年   9篇
  1968年   11篇
  1966年   13篇
  1965年   6篇
排序方式: 共有2384条查询结果,搜索用时 62 毫秒
21.
22.
When a large inorganic acid load is ingested by normals, the proton load is eliminated because the rate of excretion of ammonium can rise to 200 to 300 mmol/day. In subjects with ketoacidosis of chronic fasting, such a large increase in the rate of excretion of ammonium might not be possible because of ATP balance considerations in proximal cells. Subjects with ketoacidosis of chronic fasting excreted less net acid as defined in the conventional way when they consumed a large inorganic acid load (136 +/- 6 vs. 176 +/- 26 mmol/day in control fasted subjects). Nevertheless, the vast majority of this inorganic acid load was eliminated because they were in steady state and had only a slightly lower concentration of bicarbonate (13 +/- 0.6 vs. 15 +/- 0.5 mmol/liter) and ketoacid anions (3.3 +/- 0.2 vs. 5.5 +/- 0.2 mmol/liter) in their blood. Using a definition of net acid excretion where the component of bicarbonate loss was expanded to include "potential bicarbonate" (ketoacid anions) in the urine, the rate of excretion of net acid was higher in subjects who ingested the inorganic acid load, owing to a much lower rate of excretion of ketoacid anions (9 +/- 2 vs. 120 +/- 7 mmol/day). This lower rate of excretion was not only due to a lower filtered load, but also to a higher fractional reabsorption of ketoacid anions during acidosis (97 +/- 0.1 vs. 77 +/- 0.2%). This higher fractional reabsorption could not be explained by a lower filtered load of ketoacid anions or to a restricted intake of sodium.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
23.
SCL gene rearrangement is the most common molecular lesion (25%) identified so far in T-cell acute lymphoblastic leukemia (T-ALL). Since the frequency of T-ALL appears to be relatively higher in developing countries, we wished to determine as to what fraction of T-ALL from this population harbor SCL rearrangements. We show in this study that although the overall frequency of SCL/SIL rearrangements in T-ALL is similar to the Western countries this is at the expense of increased type A rearrangements. Whether the paucity of type B rearrangements reflects a difference in disease etiology in this part of the world is to be determined.  相似文献   
24.
Capsular metaplastic changes described as "synovial metaplasia" have been reported in association with silicone gel breast prostheses. Initially this finding was thought to be more common with textured implants. Recent studies have shown no relation between implant shell type (textured vs. smooth). The incidence of this metaplasia has been shown to decrease with the age of the implant, suggesting that it is a transitional finding in capsular maturation. The metaplastic cells in the synovial metaplasia may have secretory characteristics, but the exact etiology and function of the metaplasia are not yet fully understood. Experimentally, a similar connective tissue reaction has been induced by repeated injections of air to produce the so-called "air pouch." The current study describes cartilaginous metaplasia in the capsule surrounding a silicone-filled, Cronin-type, Dacron-backed breast prosthesis. At 26 years after bilateral breast augmentation, this patient presented with breast pain and firmness. During surgical removal the implants were intact but the capsules were densely hyalinized, irregularly calcified, and on one side there was cartilaginous metaplasia within the connective tissue of the capsule. This had occurred independently of calcification. This was believed to be an unusual tissue response. Review of the English literature failed to identify a comparable case.  相似文献   
25.
This report describes the balloon-gas procedure, a technique for obtaining large volumes of intraocular gas. With the balloon-gas procedure a kind of "external fluid-gas exchange" allows for the safe injection of up to 1.0 ml of gas without previous pars plana vitrectomy or surgical drainage of subretinal fluid. From April 1985 to October 1988, in Tübingen, this procedure was utilized in 36 retinal detachments with breaks not suited for scleral buckling: giant tears (nine eyes), large dialyses (seven eyes), posterior breaks (16 eyes), and multiple breaks at different latitudes (four eyes). Follow-up ranged from six to 28 months (average 16 months). Initial retinal reattachment was achieved in 28 eyes (77.8%). Reasons for initial failure were proliferative vitreoretinopathy in six eyes, and a missed break in two. Redetachment occurred in three eyes. All 11 failures were reoperated using segmental sponges (eight eyes) and gas injection (three eyes). Final reattachment was achieved in 29 of the 36 eyes (80.6%), and final failure was due to proliferative vitreoretinopathy in all seven detachments.  相似文献   
26.
Balloon occlusion is the accepted treatment for direct post-traumatic caroticocavernous fistula. We present a case of bilateral traumatic fistulae associated with a pseudoaneurysm. Resolution of both fistulae occurred following treatment of one of them by balloon occlusion of the internal carotid artery. This case highlights the importance of considering a more conservative approach to bilateral fistulae or those associated with a pseudoaneurysm. We review other treatment options. Received: 1 October 1999/Accepted: 20 October 1999  相似文献   
27.
In a group of 35 patients with relapsed and/or chemo-resistant non-Hodgkin's lymphoma (NHL), low-dose total body irradiation (LTBI) (+involved-field radiotherapy to bulky sites) achieved a complete remission rate of 29%, 2-years progression-free survival of 32% and a median progression-free survival of 12 months. The 2-year survival was 42% and the median survival was 17 months. Immuno-staining and flow cytometry of peripheral blood in 14 patients showed that LTBI leads to a significant increase in the percentage of CD4+ cells with a consequent significant increase in the CD4+/CD8+ ratio. High lymphocytic percent and a high percentage of CD4+ cells before LTBI were significantly correlated with longer response duration and overall survival. These data may suggest that the palliative potential of LTBI should be investigated as an alternative to chemotherapy in NHL patients. The pre-treatment percentage of lymphocytes and CD4+ cells may be used as predictors for response to LTBI.  相似文献   
28.
29.
Hypertrophic cardiomyopathy (HCM) is the most common genetically transmitted cardiomyopathy. In patients resistant to medical management, myectomy is the surgical procedure of choice to reduce the symptoms of left ventricular outflow obstruction. Two‐dimensional transesophageal echocardiography (2DTEE) has become part of the operative procedure by decreasing the incidence of postoperative complications. However, because of the three‐dimensional geometry of left ventricular outflow tract, it is unable to comprehensively assess the location and severity of the obstruction and to provide accurate guidance during myectomy. In this study, 10 patients with HCM underwent live/real time three‐dimensional transesophageal echocardiography (3DTEE) intra‐operatively to measure the volume of the resected septum. This volume correlated well with the volume of the resected septal muscle directly obtained using a graduating cylinder containing water (r = 0.9, P < 0.000). 3DTEE may be potentially used as an adjunct to guide the surgeon in performing an adequate myectomy with a lower incidence of residual obstruction and complications such as an iatrogenic ventricular septal defect.  相似文献   
30.
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