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   1244篇
  免费   84篇
  国内免费   6篇
耳鼻咽喉   22篇
儿科学   58篇
妇产科学   16篇
基础医学   189篇
口腔科学   16篇
临床医学   125篇
内科学   189篇
皮肤病学   8篇
神经病学   228篇
特种医学   89篇
外科学   92篇
综合类   25篇
一般理论   2篇
预防医学   165篇
眼科学   6篇
药学   83篇
中国医学   2篇
肿瘤学   19篇
  2023年   8篇
  2021年   32篇
  2020年   14篇
  2019年   24篇
  2018年   16篇
  2017年   13篇
  2016年   15篇
  2015年   25篇
  2014年   31篇
  2013年   50篇
  2012年   47篇
  2011年   54篇
  2010年   32篇
  2009年   31篇
  2008年   58篇
  2007年   66篇
  2006年   59篇
  2005年   72篇
  2004年   44篇
  2003年   48篇
  2002年   38篇
  2001年   41篇
  2000年   40篇
  1999年   35篇
  1998年   20篇
  1997年   24篇
  1996年   21篇
  1995年   19篇
  1994年   12篇
  1993年   20篇
  1992年   19篇
  1991年   15篇
  1990年   15篇
  1989年   21篇
  1988年   18篇
  1987年   16篇
  1986年   19篇
  1985年   13篇
  1984年   10篇
  1983年   13篇
  1981年   9篇
  1976年   9篇
  1973年   17篇
  1972年   8篇
  1971年   10篇
  1970年   7篇
  1969年   7篇
  1968年   7篇
  1967年   10篇
  1966年   7篇
排序方式: 共有1334条查询结果,搜索用时 15 毫秒
1.
2.
Mutations in SNCA and LRRK2 genes, encoding alpha-synuclein and leucine-rich repeat kinase 2, respectively, cause autosomal dominant Parkinson's disease (AdPD). The LRRK2 G2019S (c.6055G > A) and R1441G (c.4321C > G) mutations have also been identified in sporadic PD (sPD). We studied 55 unrelated patients with AdPD, 235 patients with sPD, and 235 healthy age- and gender-matched controls all of Greek origin. Patients with AdPD were screened for SNCA and LRRK2 mutations by direct sequencing. SNCA gene dosage analysis was also performed for AdPD using quantitative duplex polymerase chain reaction of genomic DNA. In addition, we investigated the frequency of the LRRK2 G2019S mutation in sPD. We found no missense mutations or multiplications in the SNCA gene. Here we report two novel variants, A211V (c.632C > T) and K544E (c.1630A > G) in LRRK2 gene in two patients with AdPD that was not present in controls. We identified only one patient with sPD (1/235; 0.4%) carrying the G2019S mutation. LRRK2 mutations are present in AdPD and sPD patients of Greek origin.  相似文献   
3.
4.
Two seemingly unrelated events--decentralization of the nursing organization and promotion of nurse executives into patient care services vice presidencies with authority over many departments--prompt the authors to ask the question, "Who is leading the nursing department?" The authors discuss the impact of these trends on the nursing organization and make suggestions for ensuring strong nursing leadership.  相似文献   
5.
Image-directed percutaneous biopsies with a biopsy gun   总被引:3,自引:0,他引:3  
Core tissue for histologic study is believed by many pathologists to be more diagnostic than material from needle aspiration. Recently, a biopsy "gun" has been introduced, which simplifies core biopsies. With this device, 182 biopsies of multiple anatomic sites were performed with ultrasonic, computed tomographic, and fluoroscopic guidance and 18-gauge needles. High-quality histopathologic specimens were obtained in 177 of the biopsies, and diagnostic target tissue was obtained in 167. Only three significant complications occurred: one bleeding complication that required transfusion and two cases of pneumothorax that necessitated placement of chest tubes. The biopsy gun eliminated the disjointed movements of conventional "skinny" needle biopsies, and none of the samples demonstrated significant "crush" artifact or obscuring blood, problems that are commonly associated with manual biopsy techniques. Patient discomfort was decreased with this system compared with that of manual biopsies, and the total procedure time was reduced. Because of these distinct advantages, the authors now use the biopsy gun exclusively for all percutaneous biopsies and recommend that other institutions consider the use of this biopsy method.  相似文献   
6.
7.
The authors hypothesized that the progesterone component of some hormone replacement therapies in women is detrimental to cognition. A previous study showed that ovariectomy (ovx) in aged rats enhanced spatial working memory and decreased elevated progesterone levels. The current study evaluated whether progesterone administration counteracts these cognitive enhancing effects of ovx. Aged sham and aged ovx rats given progesterone exhibited compromised learning of the working and reference memory components of the task, and made more working memory errors on the latter testing days compared with aged ovx rats not given progesterone. Results suggest that whereas ovx of the aged female rat enhances learning and the ability to handle numerous items of spatial working memory information, progesterone is detrimental to these aspects of performance. These findings may speak to studies in menopausal women which suggest that combination hormone therapies have a negative impact on cognition.  相似文献   
8.
9.
We compared the immediate effects of five beta-adrenoreceptor-blocking agents in 16 patients with stable angina pectoris. Acute dose-response studies showed that all five drugs improved exercise tolerance and reduced ST-segment depression, heart rate and blood pressure by a similar degree in comparison with a placebo (P less than 0.01). Near maximum improvement in exercise tolerance occurred when the acute cumulative oral dose had reached 160 mg for propranolol and oxprenolol, 200 mg for metoprolol and tolamolol and 400 mg for practolol. When these drugs were administered as a single doses, increase in walking time before the development of angina and reduction in ST-segment depression, heart rate and systolic blood pressure all occurred within one hour and persisted for eight hours--effects markedly different from the response to a placebo (P less than 0.01). These data show that non-cardioselective agents (propranolol and oxprenolol), cardioselective agents (practolol, metoprolol and tolamolol), as well as drugs with intrinsic sympathomimetic activity (oxprenolol and practolol), were equally effective in the treatment of angina pectoris.  相似文献   
10.
Part of the natural history of follicle center lymphoma (FCL) is transformation to a more aggressive neoplasm, almost always a diffuse large B-cell lymphoma. We describe a rare example of a precursor B-lymphoblastic transformation of grade I FCL occurring in a 45-year-old woman 12 years after initial presentation and 3 years after successful treatment for a diffuse large cell transformation. The lymphoblastic lymphoma shared the same immunoglobulin heavy chain gene rearrangement as the FCL as assessed by polymerase chain reaction amplification and direct sequencing, as well as identical kappa light chain gene rearrangements by Southern blot analysis. The immunoglobulin heavy chain variable gene sequences of both tumors showed numerous identical base substitutions compared with germline sequences and 3 additional mutations in the lymphoblastic lymphoma not present in the low-grade FCL. These results indicate origin of the lymphoblastic process from the mature follicle center B-cell clone, rather than divergent origin of the 2 tumors from a common immature B-cell precursor.  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