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   27828篇
  免费   1347篇
  国内免费   97篇
耳鼻咽喉   322篇
儿科学   687篇
妇产科学   703篇
基础医学   3723篇
口腔科学   1686篇
临床医学   2082篇
内科学   6689篇
皮肤病学   567篇
神经病学   2157篇
特种医学   535篇
外科学   3075篇
综合类   130篇
一般理论   15篇
预防医学   3274篇
眼科学   405篇
药学   1904篇
中国医学   150篇
肿瘤学   1168篇
  2023年   262篇
  2022年   237篇
  2021年   693篇
  2020年   409篇
  2019年   707篇
  2018年   1161篇
  2017年   705篇
  2016年   720篇
  2015年   869篇
  2014年   951篇
  2013年   1281篇
  2012年   2288篇
  2011年   2492篇
  2010年   1140篇
  2009年   785篇
  2008年   1851篇
  2007年   1973篇
  2006年   1744篇
  2005年   1666篇
  2004年   1487篇
  2003年   1359篇
  2002年   1235篇
  2001年   452篇
  2000年   498篇
  1999年   364篇
  1998年   97篇
  1997年   50篇
  1996年   46篇
  1995年   49篇
  1994年   32篇
  1993年   40篇
  1992年   223篇
  1991年   160篇
  1990年   136篇
  1989年   118篇
  1988年   99篇
  1987年   99篇
  1986年   86篇
  1985年   71篇
  1984年   54篇
  1983年   54篇
  1979年   30篇
  1975年   38篇
  1974年   50篇
  1973年   29篇
  1971年   34篇
  1970年   38篇
  1969年   32篇
  1968年   38篇
  1967年   29篇
排序方式: 共有10000条查询结果,搜索用时 753 毫秒
21.
Serum lactate is a non-specific marker of tissue hypoperfusion. Elevated serum lactate is used in the differential diagnosis of acute intestinal ischemia. Although this practice is controversial, in the absence of other validated markers lactate is still used because of its high sensitivity.We present the cases of two patients who developed acute mesenteric ischemia as a post-surgical complication. The patients reported moderate abdominal pain —a non-specific symptom in the postoperative context— and tests showed progressively increasing serum lactate levels, which facilitated suspicion and subsequent diagnostic confirmation through an imaging test.These cases highlight the physiopathological importance of lactate elevation in the perioperative context and of performing a differential diagnosis of its possible causes, including mesenteric ischemia. Although the outcome was negative in the first case, early suspicion allowed us to make an effective diagnosis and administer appropriate treatment in the second patient.  相似文献   
22.
Objective: M-mode and 2D have been proposed for evaluating fetal myocardial thickness. However, studies comparing the performance of both modalities are lacking. We aimed to compare 2D versus M-mode reproducibility for assessing myocardial wall thicknesses.

Methods: A prospective study including 45 healthy fetuses from low-risk pregnancies evaluated between 18 and 41 weeks of gestation. Left and right ventricular free-wall and septal myocardial thicknesses were measured at end-diastole (ED) and end-systole (ES) in transverse 4-chamber view using 2D and M-mode. Intra- and interobserver reproducibility was evaluated by the concordance correlation coefficient (CCC). Both techniques were compared by t-test of the CCC.

Results: 2D and M-mode demonstrated excellent and similar intraobserver repeatability, with the best concordance in ES septal thickness (M-mode CCC 0.956 versus 2D-mode CCC 0.914). Interobserver reproducibility demonstrated also a high concordance, optimal in ES left ventricular free wall (M-mode 0.925 versus 2 D 0.855). Comparison of both techniques demonstrated a high concordance in all measurements, except for ED septal thickness with better reproducibility using M-mode (CCC 0.954 versus 0.847, p?=?.017).

Conclusions: 2D and M-mode can be used in a reproducible manner for measuring fetal myocardial thickness, with a slightly better performance of M-mode for assessing ED septal wall thickness.  相似文献   
23.
24.
Using 3,3'-diclorophenolsulfoftaleinil N-acetyl-beta-D-glucosaminide as a substrate, the apparent activation energy of beta-N-acetylhexosaminidase (Hex) was determined in samples of plasma and urine, as well as in leukocyte and platelet lysates. Incubation with papain produced an increase in this thermodynamic variable for plasma Hex (precursor forms with high molecular mass) that would be caused by the proteolytic action of papain on the Hex A isoenzyme. However, digestion with papain did not significantly modify the activation energy of Hex in leukocyte and platelet lysates (mature enzymatic forms). In 11 healthy subjects and 28 patients with different renal diseases, no statistically significant differences were found with regard to the values obtained in cellular lysates for variations in the activation energy of urinary Hex, regardless of whether they presented normoalbuminuria, microalbuminuria or macroalbuminuria. These results support the hypothesis that even in patients with proteinuria, no significant amounts of plasma Hex precursor forms are found in urine samples, and the source of the enzyme activity is the kidney itself.  相似文献   
25.
26.
27.
PURPOSE: Temporomandibular joint (TMJ) arthroscopy has been considered a safe surgical procedure in the treatment of TMJ derangement. However, it is not exempt from complications. This study evaluates the complications of arthroscopy in patients with internal derangement of TMJ. PATIENTS AND METHODS: Five hundred consecutive patients (670 joints) with TMJ derangement who underwent arthroscopy between 1995 and 2004 were retrospectively analyzed. All the patients were classified as II to V in the Wilkes classification. Lysis and lavage, electrocautery of the posterior ligament, injection of corticoids, injection of ethanolamine, myotomy of lateral pterygoid muscle attachments, myotomy and electrocautery, motor debridement, injection of sodium hyaluronate, and meniscal suture were performed in different patients. RESULTS: Complications were recognized during or immediately after the surgery. They were observed in 5 of 341 (1.26%) arthroscopies of the right TMJ and 4 of 329 (1.21%) arthroscopies of the left TMJ. A 1.34% complication rate was found in the whole series. No blood clots within the external auditory canal were observed. Bleeding within the superior TMJ space was observed in 57 cases (8.5%), 36 of them in the right TMJ and 21 in the left TMJ, but they were not considered as true complications. Lacerations of the external auditory canal were found in 2 cases (0.3%), with no cases of perforation of the tympanic membrane. Lesion of the auriculotemporal nerve was observed in a case. Paresia of the facial nerve was found in 4 cases (0.6%). Alteration of visual accuracy of the ipsilateral eye was also observed in a patient immediately after the surgery. CONCLUSION: Special care must be taken to reduce complications within the upper joint space by means of an adequate instrumentation and by paying attention to essential points of the arthroscopic technique.  相似文献   
28.
29.
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