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   7630篇
  免费   546篇
  国内免费   21篇
耳鼻咽喉   74篇
儿科学   277篇
妇产科学   86篇
基础医学   1330篇
口腔科学   293篇
临床医学   670篇
内科学   1195篇
皮肤病学   247篇
神经病学   862篇
特种医学   334篇
外科学   940篇
综合类   61篇
一般理论   2篇
预防医学   396篇
眼科学   302篇
药学   574篇
中国医学   10篇
肿瘤学   544篇
  2023年   26篇
  2022年   43篇
  2021年   109篇
  2020年   96篇
  2019年   82篇
  2018年   136篇
  2017年   108篇
  2016年   149篇
  2015年   187篇
  2014年   219篇
  2013年   289篇
  2012年   442篇
  2011年   428篇
  2010年   286篇
  2009年   296篇
  2008年   509篇
  2007年   454篇
  2006年   464篇
  2005年   468篇
  2004年   504篇
  2003年   452篇
  2002年   436篇
  2001年   149篇
  2000年   122篇
  1999年   128篇
  1998年   112篇
  1997年   105篇
  1996年   82篇
  1995年   64篇
  1994年   61篇
  1993年   53篇
  1992年   64篇
  1991年   66篇
  1990年   77篇
  1989年   81篇
  1988年   58篇
  1987年   54篇
  1986年   47篇
  1985年   45篇
  1984年   37篇
  1983年   29篇
  1982年   40篇
  1981年   28篇
  1980年   29篇
  1979年   32篇
  1978年   26篇
  1977年   31篇
  1973年   26篇
  1972年   26篇
  1970年   22篇
排序方式: 共有8197条查询结果,搜索用时 15 毫秒
1.
2.
3.
Facet joints play an important role in intervertebral load transmission and are crucial for rotational kinematics. Clinically, the role of facet joints as a possible source of low back pain is seen as controversial and at present is not sufficiently investigated. In this study, human lumbar facet (zygapopyhysial) joints from donors with advanced age were analyzed macroscopically, for degenerative changes. The aim was to determine the extent and morphology of degenerative changes in these joints. Lumbar facet joints (L1–L5) of 32 donors were studied (mean age 80.1±11.2 years). Joint capsules were carefully removed and joint surfaces (5 zones) examined using magnifying glasses and probes. In the result, the majority of facet joints showed cartilage defects of varying extent. Defects were located mostly at the margins of the articular surface, the central zone being relatively well preserved. Defect localization was different between superior (most cartilage defects in superior zone) and inferior (most defects inferiorly) facets. Further, defects were more severe caudal (level of L5) and in older persons. Osteophytes were present in up to 30%, located mostly at the latero-dorsal enthesis of the joint capsule on the superior facet. In conclusion, most margins of the articular facets are subject to degenerative changes in the lumbar spine of elderly persons, the topographical pattern being different in superior and inferior facets. This observation can be explained by the segmental motion patterns during extension/flexion movements of the facets. Sometimes, due to the marginal extension, it is obvious that not all changes can be assessed by CT or MRI.  相似文献   
4.
Adamantinoma of long bones is one of the rarest of malignant bone tumors; it is commonly located in the middle or lower third of the diaphysis of the tibia. A case with multiple occurrences affecting both the tibia and fibula is presented. En bloc resection with wide operative margins was performed, and a large tibial defect of 23 cm was effectively bridged by a revascularized free fibular flap. At 13 months follow-up, there was no sign of local recurrence or metastasis, and the patient was mobile.  相似文献   
5.
6.
Alzheimer's disease (AD) patients often present with concurrent major depression (MD). To investigate the reasons for this comorbidity, e.g. MD being a risk factor for AD, or both diagnoses having a common neurobiology, the temporal relationship between the first onset of AD and of MD during lifetime was investigated-57 out of 146 AD patients had a lifetime diagnosis of MD. The correlation between the ages at onset of MD and dementia was calculated. The incidence of MD in AD patients in several 5-year-intervals before and after the onset of AD was compared with the average incidence of MD in the present AD sample and with the expected incidence of MD in the general population. No significant correlation between the onset of AD and of MD could be found after controlling for age, gender and the Mini-Mental-State. However, the incidence of MD 5 years before and after the onset of AD significantly exceeded the expected incidences-MD is only partially related to AD. However, the increased incidence of MD within 5 years before and after the onset of dementia may indicate that a common neurobiological process causes cognitive decline and depression in a subsample of AD patients.  相似文献   
7.
8.
9.
Lymphocytes continuously migrate through the body, and their efficient extravasation from the blood via high endothelial venules (HEV) is essential for initiating an appropriate immune response. Most investigations have focused on the lymphocyte/HEV interaction in vitro. However, to what extent such systems reflect the situation in vivo is not known. It is also unclear whether lymphocyte subsets immigrate into the HEV in proportion to their presence in the blood, and whether import capacity is limited by the HEV. When rat mesenteric lymph node lymphocytes were incubated in vitro on cryostat sections, the well-known preferential binding of B lymphocytes to HEV of Peyer's patches (PP) and T cells to HEV of axillary lymph nodes (axLN) was observed (axLN vs. PP: B lymphocytes 21.2 ± 5.0% vs. 40.6 ± 11.0%, T lymphocytes 84.6 ± 6.3% vs. 56.5 ± 12.9%). However, when labeled mesenteric lymph node lymphocytes were injected and their location within the HEV was analyzed 15 min later, no preferential interaction was seen. After injection of labeled thoracic duct lymphocytes, the percentage of labeled cells among B and T lymphocytes in the blood was significantly different (4.4 ± 0.9% vs. 8.9 ± 3.6%), whereas that in HEV of axLN (19.0 ± 6.4% vs. 16.6 ± 6.0%) and PP (30.6 ± 6.1% vs. 33.9 ± 4.4%) was comparable. Although the number of injected lymphocytes was similar in magnitude to the total blood lymphocyte pool, after injection there was no increase in lymphocyte numbers in the HEV. Thus, the adhesion assay in vitro does not completely reflect immigration into HEV in vivo. In addition, our data suggest that both the availability of lymphocyte subsets in small venules and the immigration rate into HEV are actively regulated in vivo.  相似文献   
10.
We report on the successful regrafting of a transplanted liver. The donor liver was first grafted into a patient suffering from cryptogenic cirrhosis; the patient died 1 day after the elective transplantation of cerebral bleeding. The well-functioning graft was harvested again and transferred to our institution. After another 12 h of cold ischemia, the liver was reperfused in an urgently registered patient with recurrence of hepatitis B in his first graft. The transplantation was successfully performed and the patient is now doing well, more than 5 months after regrafting with the reused liver. Received: 21 October 1996 Received after revision: 9 January 1997 Accepted: 27 January 1997  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