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   40302篇
  免费   1922篇
  国内免费   197篇
耳鼻咽喉   532篇
儿科学   739篇
妇产科学   418篇
基础医学   5029篇
口腔科学   1272篇
临床医学   2721篇
内科学   9248篇
皮肤病学   898篇
神经病学   3567篇
特种医学   2028篇
外国民族医学   1篇
外科学   6328篇
综合类   154篇
一般理论   6篇
预防医学   1308篇
眼科学   823篇
药学   2629篇
中国医学   101篇
肿瘤学   4619篇
  2023年   213篇
  2022年   391篇
  2021年   696篇
  2020年   402篇
  2019年   525篇
  2018年   655篇
  2017年   584篇
  2016年   731篇
  2015年   703篇
  2014年   906篇
  2013年   1144篇
  2012年   1864篇
  2011年   1897篇
  2010年   1155篇
  2009年   1002篇
  2008年   1725篇
  2007年   2003篇
  2006年   1880篇
  2005年   1843篇
  2004年   1840篇
  2003年   1749篇
  2002年   1772篇
  2001年   1364篇
  2000年   1462篇
  1999年   1344篇
  1998年   550篇
  1997年   447篇
  1996年   440篇
  1995年   346篇
  1994年   333篇
  1993年   316篇
  1992年   1014篇
  1991年   865篇
  1990年   830篇
  1989年   836篇
  1988年   778篇
  1987年   767篇
  1986年   680篇
  1985年   634篇
  1984年   440篇
  1983年   351篇
  1979年   299篇
  1978年   203篇
  1977年   181篇
  1974年   191篇
  1973年   163篇
  1972年   163篇
  1971年   181篇
  1970年   156篇
  1969年   179篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
The characteristics of motor function and brain dopamine (DA) metabolism in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-treated mice after immersion immobilization stress were investigated. There was no significant difference in locomotor activities between MPTP-treated and saline-treated mice, but locomotor activities of MPTP-treated mice after stress decreased more remarkably than those of saline-treated mice. Immediately after stress, striatal DA concentrations of MPTP-treated mice were significantly lower than those of saline-treated mice. Striatal DA levels improved when 24 h passed after stress. The striatal and cortical (DOPAC + HVA)/DA ratios of MPTP-and stress-treated mice was significantly higher than that of saline-and stress-treated mice. It is due to the decreased DA level and the enhancement of DA turnover that MPTP-treated mice became remarkably akinetic after stress, and that L-DOPA therapy is not effective when the symptoms in patients with Parkinson's disease worsen due to stress.  相似文献   
82.
Recently, many papers have reported the development of severe pulmonary stenosis after an arterial switch operation (ASO) for the transposition of the great arteries (TGA) with intact ventricular septum (IVS) in the early neonate. However, supravalvular aortic stenosis after the same procedure is very uncommon. We experienced supravalvular aortic stenosis which developed gradually after successfully performing the Lecompte maneuver for TGA with IVS in a 6-day-old baby. We underwent Doty's extended aortoplasty in his 11th-month. We approached the aorta through the transection of the pulmonary trunk which was located just before the aorta. At the stenotic parts of the aorta, a discrete projection of cicatricial tissue was observed mainly at the posterior wall. The projection of the cicatricial tissue seemed to be induced as a consequence of the contraction of the aortic wall where a continuous suture was tied too tightly with non-absorbable suture materials. To prevent this complication after the Lecompte maneuver for TGA with IVS in the neonate, it is important to take care not to tie the suture too tightly and to use absorbable suture materials for construction of the aorta. There are the recommendations which we observed would prevent the post-operative complication of supravalvular aortic stenosis. As a final note, in repairing the supravalvular aortic stenosis, an approach through the transection of the pulmonary trunk was very useful.  相似文献   
83.
84.
Two strains of T. rubrum and one strain of T. mentagrophytes were inoculated into human skin grafted onto BALB/c nude mice by the needle puncture method. Infection was established in 1 of the 10 animals inoculated with fluffy colony type T. rubrum, 2 of the 10 animals inoculated with powdery colony type T. rubrum, and 7 of the 10 animals inoculated with granular colony type T. mentagrophytes, suggesting that the skin grafts are infectible by anthropophilic and zoophilic strains of dermatophytes. T. rubrum infection continued for a maximum of 9 weeks and T. mentagrophytes infection for more than 11 weeks. In the animals inoculated with T. mentagrophytes, fungal elements were localized in the stratum corneum of the human skin grafts. In the acute stage, microabscesses consisting of neutrophils were observed under the stratum corneum in contact with fungal elements; in the chronic stage, epidermal thickening and infiltration, mainly consisting of histiocytes and a smaller number of lymphocytes, was noted in the upper and middle dermis. Ultrastructural findings from the parasites were similar to those of dermatophytosis in man. This experimental system should be useful as a model of chronic dermatophyte infection in the human skin.  相似文献   
85.
We made an attempt to detect organic brain lesions in eight patients with myotonic dystrophy (MyD) using X-ray computed tomography (CT) and magnetic resonance imaging (MRI). The patients comprised seven men and one woman with ages ranging from 41 to 58 years (average 47 +/- 5.3 years). Seven patients had intellectual impairment assessed using an intelligence quotient test (WAIS-R < 70). CT scans were obtained in the axial plane with a slice thickness of 10 mm, and MRI scans were performed on a 1.5 tesla system in the axial and coronal sections with a slice thickness of 8 mm. CT scans displayed both marked sulcal and prominent ventricular enlargement in 6 of the 8 patients, indicating the presence of brain atrophy, and 3 cases had a few paraventricular low density area in the cerebral hemispheres. In contrast to CT, MRI study revealed more widespread brain parenchymatous lesions in all the 8 cases, showing the multiple foci of high signal intensity with varying size in the white matter on T2-weighted images and proton density-weighted images. No visible changes were detected on CT or MRI in the brain stem and cerebellum. The present study demonstrated that there exist organic cerebral lesions, predominantly located in the white matter in patients with MyD, regardless of focal neurological symptoms. The parenchymatous lesions in the brain can be detected with MRI, and lesser extent with CT, and are considered to be intimately correlated with intellectual deterioration commonly seen in patients with MyD.  相似文献   
86.
EDTA-extractable protein (EEP) is a major extrinsic protein of lens fiber membrane. The EEP of calf lens separated three major bands by SDS-PAGE, and the molecular weights of these major bands were 34 kilodalton (kd.), 33 kd. and 32 kd. Combination of EEP with F-actin and some kinds of phospholipid containing liposomes depends on Ca2+. In two-dimensional gel electrophoresis, some spots of the calf-EEP partially overlapped with spots of lipocortin, which is a substrate for epidermal growth factor receptor/kinase and an inhibitor of phospholipase A2. The 34 kd. protein of the EEP cross-reacted to the antibody prepared against lipocortin of pig's aorta: These results suggest the important function of EEP in lens.  相似文献   
87.
88.
A time course study on the appearance and distribution of cells immunoreactive for spot 35 protein, a novel cerebellar Purkinje cell-specific protein, was conducted in the developing cerebella of fetal and early postnatal rats by PAP immunohistochemistry. Spot 35-immunoreactive cells were first noted in the cerebellar anlage on the 17th embryonic day, appearing as large cellular aggregations in the mantle layer and a small number of elongated cells dispersed between the cell aggregations and the ependymal layer. As the development proceeded, the spot 35-immunoreactive cells gradually accumulated beneath the external granular layer. At birth, they were arranged compactly in 4-5 irregular rows to form a primitive Purkinje cell layer. During their subsequent development, immunostaining for spot 35 protein demonstrated the rearrangement of the Purkinje cells into a single row and the maturation of their somata, axons and dendrites. All these findings indicate that spot 35 protein is a specific marker for the cerebellar Purkinje cells, from their migrating stage throughout the course of their maturation. The present study further describes the transitory lamellar arrangement of spot 35-immunoreactive Purkinje cells located horizontally at a short distance away from the ependymal layer of the cerebellum on the 17th embryonic day.  相似文献   
89.
The mechanism by which prostacyclin acts to prevent in vivo reperfusion injury is still uncertain. This study was therefore undertaken to assess the effect of a stable prostacyclin analogue (OP 41483-alpha-CD [OP]) on oxygen-derived free radicals after heart-lung transplantation. OP was administered to the heart-lung graft through the pulmonary artery for 25 minutes encompassing the reperfusion process. Free radicals were directly measured by electron spin resonance spectroscopy. The radical intensities of pulmonary venous blood were significantly lower in the OP group than in the control group, suggesting that fewer free radicals were generated in the lungs of the OP group. The cardiac and respiratory function were better in the OP group than in the control group. The lung is the primary source of oxygen free radical attack, and the beneficial action of OP on free radical generation is almost exclusively restricted to the lung and does not apply to the heart. This result suggested that OP probably is effective in inhibiting free radical generation from the endothelium.  相似文献   
90.
An automated measurement of total and free hydroxyproline in serum or urine is presented that uses flow injection analysis. After exclusion of nonspecific substances, hydroxyproline was oxidized by chloramine- T and L-cysteine with Ehrlich's reagent. The linearity obtained was from 3.8μmole/ L to 1.22 mmole/L with good precision (CV <3%). Comparison of the proposed method with HPLC yielded r = 0.939 as the correlation coefficient. Reference intervals of free and total hydroxyproline are 1.4–9.7 μmole/L, 3.8–27.2 μmole/L for serum, and 10.0–72.5 μmole/L, 25.2–303.6 μmole/L for urine, respectively. Serum free and total hydroxyproline levels in renal osteodystrophy patients on maintenance hemodialysis (N = 71) were significantly higher than in controls (P<0.0001). This method is superior to the use of HPLC with regard to stability of the color reaction. The measurement of serum free and total hydroxyproline is a useful marker for therapeutic observation of renal osteodystrophy patients. © 1994 Wiley-Liss, Inc.  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