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   9191篇
  免费   413篇
  国内免费   85篇
耳鼻咽喉   84篇
儿科学   203篇
妇产科学   186篇
基础医学   1074篇
口腔科学   212篇
临床医学   624篇
内科学   2387篇
皮肤病学   160篇
神经病学   601篇
特种医学   498篇
外科学   1650篇
综合类   16篇
一般理论   1篇
预防医学   343篇
眼科学   145篇
药学   530篇
中国医学   22篇
肿瘤学   953篇
  2023年   42篇
  2022年   87篇
  2021年   193篇
  2020年   107篇
  2019年   158篇
  2018年   197篇
  2017年   143篇
  2016年   174篇
  2015年   169篇
  2014年   232篇
  2013年   282篇
  2012年   409篇
  2011年   447篇
  2010年   302篇
  2009年   265篇
  2008年   440篇
  2007年   521篇
  2006年   480篇
  2005年   473篇
  2004年   472篇
  2003年   510篇
  2002年   481篇
  2001年   295篇
  2000年   266篇
  1999年   255篇
  1998年   133篇
  1997年   101篇
  1996年   94篇
  1995年   69篇
  1994年   74篇
  1993年   61篇
  1992年   174篇
  1991年   149篇
  1990年   149篇
  1989年   148篇
  1988年   114篇
  1987年   122篇
  1986年   118篇
  1985年   95篇
  1984年   67篇
  1983年   51篇
  1982年   33篇
  1981年   35篇
  1979年   76篇
  1978年   44篇
  1977年   36篇
  1973年   28篇
  1970年   30篇
  1969年   35篇
  1967年   30篇
排序方式: 共有9689条查询结果,搜索用时 15 毫秒
1.
2.
Many institutions in Japan perform PCI via the radial artery(TRI), due to the adility of TRI to improve the quality of life of patients. However, this procedure involves the significant problem of causing narrowing of the radial artery or occlusion by trans-radial approach.  相似文献   
3.
BACKGROUND AND PURPOSE: Dot-like low intensity spots (dot-like hemosiderin spots: dotHSs) on gradient echo T2*-weighted MRI have been histologically diagnosed to represent old cerebral microbleeds associated with microangiopathies. They have also been correlated to the fragility of small vessels and the tendency to bleed. Therefore, a substantial number of dotHSs might be associated with a large-sized, deep intracerebral hematoma (ICH). On the other hand, dotHSs may reflect old microbleeds that did not enlarge to symptomatic size. METHODS: To investigate how dotHSs are related to the size (maximal diameter) of primary deep ICH, we analyzed the diameter and the number of dotHSs in 151 patients with deep ICH not associated with subarachnoid hemorrhage or intraventricular hemorrhage (75 males and 76 females, age ranged from 37 to 90 [65.7 +/- 11.3 years old] who were consecutively admitted to Hakodate Municipal Hospital. The hazard ratio (HR) for a maximal diameter of deep ICH < or =2 cm was estimated, using the number of dotHSs and risk factors for stroke. RESULTS: The number of dotHSs associated with the diameter < or =2 cm was 9.2 +/- 11.5, significantly larger than that with the diameter > or =2 cm (4.7 +/- 7.0, P= .012). Multivariate analysis revealed that a maximal diameter of deep ICH of < or =2 cm was found in patients with dotHS (HR, 3.7; 95% confidence interval [CI], 1.4-10.1; P= .009). CONCLUSION: Though small sample size limited the power of our analyses, these findings suggest that the number of dotHSs may be associated with a small diameter of deep ICH.  相似文献   
4.
This cross-sectional study was conducted to examine whether the obstructive sleep apnea syndrome (OSAS) is associated with elevation of the pulse wave velocity (PWV) and increase in the plasma levels of C-reactive protein (CRP), both of which are known markers of cardiovascular risk, and also to determine if the concurrent presence of the metabolic syndrome might exacerbate this elevation in the levels of these cardiovascular risk markers in subjects with OSAS. With these objectives, the PWV and serum CRP were measured in 184 subjects attending a sleep clinic. It was found that the PWV and CRP were higher in the subjects with OSAS (n=94) than in those without OSAS (n=90). Furthermore, among the subjects with OSAS, the PWV and CRP were higher in those with the concurrent presence of the metabolic syndrome (n= 41; PWV=1,562+/-19 cm/s; CRP=1.8+/-0.2 mg/l) than in those without metabolic syndrome (n=53; PWV=1,432+/-21 cm/s; CRP=1.2+/-0.1 mg/l) (p<0.05). A general linear model analysis demonstrated that OSAS and metabolic syndrome were independently associated with elevated PWV and increase of the plasma levels of CRP. OSAS appears to be associated with increased cardiovascular risk, as reflected by both elevated PWV and increase of the plasma CRP. The concurrent presence of metabolic syndrome may exacerbate this increase in cardiovascular risk in subjects with OSAS. Therefore, the concurrent presence of metabolic syndrome may constitute an additive cardiovascular risk factor in subjects with OSAS.  相似文献   
5.
OBJECTIVES: To reveal the frequency and the clinical characteristics of dystrophic calcification that occurs in children with juvenile dermatomyositis, multi-center analysis was constructed. METHOD: Fifty children with JDM were enrolled, and 14 of them (28.0%) were complicated with calcinosis. Clinical symptoms and laboratory tests at onset, initial therapy and disease course were compared in children with and without calcinosis. RESULTS: The mean age of the onset of calcinosis was 4.78 +/- 3.33 years, and it was younger than those of children without calcinosis (8.66 +/- 3.85 years) (P = 0.0017). No differences of clinical manifestation except Gower's sign were observed. The frequency of positive anti-nuclear antibody was 7.1% in children with calcinosis and 52.9% without calcinosis (P = 0.0112). The initial therapy of methylprednisolon pulses gave no effects on prognosis of calcium deposition. The calcinosis appeared in 1.56 +/- 1.91 year after the onset of the disease. The various types of calcium deposition including large tumorous clumps, subcutaneous plaques or nodules, sheet-type calcification were deserved. They appeared over knee joints (64.3%), elbow joint (64.3%), and hip processes (50.0%). Calcinosis affecting the subcutaneous tissues frequently resulted in painful superficial ulceration of the overlying skin (42.9%), local infection (50.0%), and limitation of joint movement (14.3%). Although aluminum phosphate was effective in 2 children among 7, no other effective treatment was recommended. In 5 cases, surgical removal of tumorous clumps was operated. Thus, juvenile dermatomyositis is frequently complicated with calcinosis. This type of calcinosis was found to be unlikely to resolve completely, and resulted in severe disability in children.  相似文献   
6.
Neurotransmitter- or neuromodulator-like actions ofl-DOPA were investigated with intracellular recordings from submucous plexus neurons of the guinea-pig caecum.l-DOPA at 30 nM augmented the amplitude of fast EPSPs, but did not affect depolarizations elicited by puff application of acetylcholine (ACh). The augmenting effect ofl-DOPA on the fast EPSPs was counteracted byl-DOPA methyl ester. The fast EPSPs were depressed by 10 μMl-DOPA, but transiently augmented after rinsing the drug.l-DOPA methyl ester did not affect the inhibitory action ofl-DOPA on the fast EPSPs, but antagonized the potentiation following the inhibition. The depolarization elicited by exogenously applied. ACh was inhibited by 10 μMl-DOPA. Intracellular Ca2+ concentrations ([Ca2+]i) of the neuronal soma were measured with fura-2 microfluorophotometry. The transient increase in the [Ca2+]i evoked by the somatic action potential (Δ[Ca2+]AP) was facilitated by 30 nMl-DOPA, but decreased by the drug at 10 μM. It is concluded thatl-DOPA at low concentrations enhances the Δ[Ca2+]AP, increasing the neurotransmitter release, but at high dose diminishes the Δ[Ca2+]AP, inhibiting the neurotransmission.  相似文献   
7.
Bronchial venous plexus and its communication with pulmonary circulation   总被引:2,自引:0,他引:2  
This study was undertaken to clarify the microvascular anatomy of the normal human bronchial circulation, focusing on the bronchial venous system and its communication with the pulmonary circulation. Ten normal lungs obtained at autopsy were studied. Bronchial arteriography was performed in six lungs, pulmonary arteriography in two lungs, and pulmonary venography in another two. Using radiologic methods, including microradiography, and serial histologic sections, we found numerous bronchial venous plexuses around the airways and blood vessels into which the bronchial capillaries drained. Frequent communications of the venous plexuses with the pulmonary veins and neighboring alveolar capillaries were also demonstrated. The bronchial venous plexus and its close connection with the pulmonary circulation may be important in various pathologic conditions involving the interstitial space, such as interstitial pulmonary edema.  相似文献   
8.
9.
To elucidate the growth of the tarsal bones in congenital clubfoot, relative to the growth of these bones in the unaffected feet and compared to growth in the feet of normal volunteers, we used a computed tomography (CT) scanner to measure the volume of all tarsal bones. The subjects of the study were 10 adults (7 men and 3 women) with unilateral congenital clubfoot (average age 20 years and 1 month). As controls, we examined 11 healthy volunteers. We calculated the ratio of the volume of each tarsal bone to the total bone volume and the ratio of the volume of each tarsal bone in clubfoot to the corresponding bone in the unaffected foot. The volume ratio of each tarsal bone was compared between clubfeet and unaffected feet because the differences of each tarsal bone ratio between the normal foot group and unaffected foot group were not significant. In the clubfeet (n=10), the talus and the medial cuneiform bones were smaller than those in the unaffected feet (n=10) but the cuboid bone was larger. The growth of the navicular did not differ from as that in unaffected feet. Our results suggested hypoplasia on the medial side of the foot in adult patients with congenital clubfoot. The 3 patients who had undergone medial release showed particularly marked hypoplasia of the medial side. In congenital clubfoot cases with severe deformities who had undergone wide soft-tissue release operations, there were clear growth suppressions in the talus and the medial cuneiform. We could not determine whether the cause of the growth suppression was the hypoplastic nature of tarsal bones themselves or the surgical obstacles to tarsal bone growth.  相似文献   
10.
Staging of esophageal carcinoma in vitro with 4.7-T MR imaging   总被引:4,自引:0,他引:4  
  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