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   2465篇
  免费   188篇
  国内免费   19篇
耳鼻咽喉   20篇
儿科学   55篇
妇产科学   206篇
基础医学   326篇
口腔科学   143篇
临床医学   232篇
内科学   584篇
皮肤病学   22篇
神经病学   453篇
特种医学   52篇
外科学   228篇
综合类   4篇
一般理论   1篇
预防医学   104篇
眼科学   28篇
药学   115篇
肿瘤学   99篇
  2023年   17篇
  2022年   26篇
  2021年   77篇
  2020年   40篇
  2019年   64篇
  2018年   77篇
  2017年   68篇
  2016年   79篇
  2015年   68篇
  2014年   87篇
  2013年   110篇
  2012年   147篇
  2011年   152篇
  2010年   90篇
  2009年   77篇
  2008年   114篇
  2007年   137篇
  2006年   113篇
  2005年   108篇
  2004年   112篇
  2003年   75篇
  2002年   79篇
  2001年   53篇
  2000年   57篇
  1999年   42篇
  1998年   18篇
  1996年   15篇
  1995年   17篇
  1992年   31篇
  1991年   33篇
  1990年   29篇
  1989年   22篇
  1988年   32篇
  1987年   28篇
  1986年   18篇
  1985年   33篇
  1984年   17篇
  1983年   17篇
  1982年   14篇
  1981年   17篇
  1980年   10篇
  1979年   23篇
  1978年   11篇
  1977年   13篇
  1975年   12篇
  1974年   17篇
  1971年   12篇
  1970年   14篇
  1969年   13篇
  1968年   10篇
排序方式: 共有2672条查询结果,搜索用时 31 毫秒
1.
Nevo  N.  Goldstein  A. L.  Staierman  M.  Eran  N.  Carmeli  I.  Rayman  S.  mnouskin  Y. 《Hernia》2022,26(6):1491-1499
Hernia - The minimally invasive surgical repair of combined inguinal and ventral hernias often requires shifting from one approach or plane to another. The traditional enhanced-view totally...  相似文献   
2.
3.
Zusammenfassung An der überlebenden Extremität entwickelt sich bei Durchblutung mit Natriumarsenit ein mächtiges Ödem. Das Ödem bleibt aus, wenn man den Durchblutungsdruck auf die Hälfte herabsetzt. An der überlebenden Leber findet sich die Erscheinung nicht.Nach As2O3-Zusatz sinkt der kolloidosmotische Druck des Serums, und zwar nur, wenn das Blut mit der Extremität in Berührung war. Der Abfall des kolloidosmotischen Druckes wird als Ursache des Ödems angesehen.Wir haben demnach an der überlebenden Extremität auf drei Arten Ödem erzeugen können: 1. durch arteriellen Hochdruck, 2. durch venöse Stauung, 3. durch Herabsetzung des kolloidosmotischen Druckes.  相似文献   
4.
BACKGROUND: Cardiac magnetic resonance (MR) images are often reviewed by non-cardiologists who are not trained in the interpretation of regional left ventricular (LV) function. We hypothesized that the use of still-frame parametric MR images of wall motion could aid in the assessment of regional LV function. METHODS: Dynamic, electrocardiogram-gated, steady-state free precession (FIESTA) short-axis images were obtained in 6 to 10 slices in 18 consecutive patients. Each loop was used to automatically generate a still-frame image, in which each pixel is assigned a value equal to the amplitude of cyclic variation in local intensity, resulting in higher intensity in pixels that change between blood and tissue during the cardiac cycle. The dynamic images were reviewed by an expert cardiologist who provided gold standard grades for regional wall motion and by four radiologists. Then the radiologists reviewed and graded the same MR images in combination with parametric images. Grades assigned to each segment in the two sessions were compared with the gold standard. RESULTS: According to expert interpretation, 6 patients had normal wall motion, and 12 had wall motion abnormalities. Parametric images showed a bright band in the area spanned by endocardial motion, with reduced brightness and thickness in areas of hypokinesis. The agreement between the radiologists' grades and the gold standard significantly improved by adding parametric images (from 77% to 81%), which also resulted in reduced interobserver variability (from 52% to 33%). CONCLUSIONS: Still-frame parametric images aid in the assessment of regional wall motion by non-cardiologists who are required to interpret cardiac images.  相似文献   
5.
The functional significance of the slow excitatory synaptic potentials (EPSPs) in myenteric neurones is unknown. We investigated this using intracellular recording from myenteric neurones in guinea-pig ileum, in vitro . In all, 121 neurones responded with fast EPSPs to distension of the intestine oral to the recording site. In 28 of these neurones, distension also evoked depolarizations similar to the slow EPSPs evoked by electrical stimulation in the same neurones. Intracellular injection of biocytin and immunohistochemistry revealed that neurones responding to distension with slow EPSPs were descending interneurones, which were immunoreactive for nitric oxide synthase (NOS). Other neurones, including inhibitory motor neurones and interneurones lacking NOS, did not respond to distension with slow EPSPs, but many had slow EPSPs evoked electrically. Slow EPSPs evoked electrically or by distension in NOS-immunoreactive descending interneurones were resistant to blockade of NK1 or NK3 tachykinin receptors (SR 140333, 100 n m ; SR 142801, 100 n m , respectively) and group I metabotropic glutamate receptors (PHCCC, 10–30 μ m ), when the antagonists were applied in the recording chamber of a two-chambered organ bath. However, slow EPSPs evoked electrically in inhibitory motor neurones were substantially depressed by SR 140333 (100 n m ). Blockade of synaptic transmission in the stimulation chamber of the organ bath abolished slow EPSPs evoked by distension, indicating that they arose from activity in interneurones, and not from anally directed, intrinsic sensory neurones. Thus, distension evokes slow EPSPs in a subset of myenteric neurones, which may be important for intestinal motility.  相似文献   
6.
7.
Purpose Studies on musculoskeletal manifestations (MSM) of childhood acute lymphoblastic leukemia (ALL) have yielded variable findings with regard to their clinical impact. We investigated the significance for differential diagnosis, treatment and outcome of musculoskeletal complaints as presenting symptoms of ALL, and their correlation with leukemia immunophenotypes, for which data is lacking. Methods Data on 783 children in the national study for childhood ALL between 1984 and 2003 were reviewed retrospectively. Statistical analysis examined possible relationships between MSM at the time of diagnosis and demographic and clinical data, biological features of leukemia (peripheral blood counts, immunophenotype and main cytogenetic aberration), response to initial prednisone treatment, and outcome. Results Of 765 children with data on orthopaedic complaints, 240 presented with MSM (31.4%). Among these children, B cell precursor (BCP) was much more common (209/576, 36.3%) than T cell ALL (25/176, 14.2%). Patients with MSM had lower white blood cell counts (WBC) (median of 9 vs. 20 × 109/L, P < 0.001) and percentage of blast cells in the peripheral blood at diagnosis compared to those without (median of 27 vs. 53%, P < 0.001). Hepatomegaly and splenomegaly were less common in MSM group (67 vs. 53% <3 cm, P < 0.001, and 63 vs. 50% <3 cm, P < 0.001, respectively). Poor response to initial treatment with prednisone was recorded in 7.1% of patients with MSM versus 11.5% of those without (P = 0.086). The analysis revealed no independent effect of MSM on event-free survival (EFS), after correcting for differences in EFS related to immunophenotype or initial WBC. Conclusions MSM occur mostly in children with BCP ALL who present with less involvement of extramedullary organs, low peripheral blood blasts and white blood cells counts. These findings highlight the importance of including ALL in the differential diagnosis of MSM even in the presence of an apparently normal peripheral blood count. Our study also suggests that MSM are caused by leukemic cells with enhanced biological propensity to remain relatively confined within the intramedullary bone-marrow space.  相似文献   
8.
9.
A significant increase in urine arylsulfatase A activity (p less than 0.01) was found in patients with urothelial tumors. Arylsulfatase A activity was 1.36 +/- 1.10 U/24-h urine in control specimens, 1.90 +/- 1.66 U/24-h urine in various genitourinary tract disorders, and 3.90 +/- 1.98 U/24-h urine in transitional cell carcinoma specimens. Surgical treatment of the neoplastic patients lowered the arylsulfatase A activity found in urine to within reference values. The arylsulfatase A excreted by patients with these tumors was highly sensitive to thermal inactivation while the enzyme activity in the control urines was less affected by the heat treatment. The time course of the arylsulfatase A reaction with 4-nitrocatechol sulfate was not linear in normal individuals, while it was linear in 90% of patients with urothelial tumors. This difference in the kinetic pattern of the enzyme could be used to increase the diagnostic specificity of the determination.  相似文献   
10.
The prevalence of antibodies to 13 antigens of Legionellaceae were compared in three populations: 583 blood donors, 140 tuberculosis patients and 66 patients with acute non Legionellosis pneumonia. Antibody levels were determined by indirect immunofluorescence (IFA) using formalized antigens prepared from bacteria developed in embryonated hen yolk sac. The very weak prevalence of anti L. pneumophila antibodies in a healthy population [almost nil for serogroups 2, 3, 4 and 5; 1.5% for serogroup 6, maximum of 2.5% for serogroup 1 (titres of 16)] confirms the positive and presumptive criteria that have been recommended by Centers for Disease Control (CDC). But as regards the other Legionellae studied, these criteria cannot be applied owing to the prevalences that are higher in healthy populations (until 14.5% with levels of 16-32 and 1% with levels of 64-128 for L. bozemanii) and clearly amplified in tuberculosis patients and in acute pneumonia. Although the significance of these antibodies remains to be discussed, with formalized antigens, it seems reasonable as regards these species to assign a threshold of 256 for the presumptive and positive criteria following seroconversion.  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