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   9353篇
  免费   494篇
  国内免费   68篇
耳鼻咽喉   58篇
儿科学   190篇
妇产科学   106篇
基础医学   940篇
口腔科学   180篇
临床医学   715篇
内科学   2773篇
皮肤病学   206篇
神经病学   682篇
特种医学   268篇
外科学   1648篇
综合类   34篇
预防医学   235篇
眼科学   238篇
药学   462篇
  1篇
中国医学   17篇
肿瘤学   1162篇
  2023年   74篇
  2022年   171篇
  2021年   265篇
  2020年   132篇
  2019年   176篇
  2018年   213篇
  2017年   206篇
  2016年   240篇
  2015年   268篇
  2014年   289篇
  2013年   340篇
  2012年   567篇
  2011年   651篇
  2010年   309篇
  2009年   271篇
  2008年   423篇
  2007年   511篇
  2006年   449篇
  2005年   480篇
  2004年   399篇
  2003年   448篇
  2002年   403篇
  2001年   241篇
  2000年   298篇
  1999年   222篇
  1998年   100篇
  1997年   62篇
  1996年   76篇
  1995年   63篇
  1994年   63篇
  1993年   45篇
  1992年   162篇
  1991年   150篇
  1990年   125篇
  1989年   161篇
  1988年   108篇
  1987年   88篇
  1986年   86篇
  1985年   85篇
  1984年   52篇
  1983年   59篇
  1982年   29篇
  1981年   23篇
  1980年   23篇
  1979年   45篇
  1978年   23篇
  1976年   21篇
  1975年   23篇
  1972年   21篇
  1971年   23篇
排序方式: 共有9915条查询结果,搜索用时 15 毫秒
11.
Differential expression of protein kinase C subspecies, beta I- and beta II-PKC, derived from a single gene by alternative splicing was evidenced in the postnatal developing rat brain. Immunoblot analysis of the PKC subspecies in the whole developing brain showed that beta I-PKC was present at birth and then gradually increased, while beta II-PKC was not present at birth or on postnatal day 3, then increased rapidly from day 7 to the maximum value seen in the adult brain. Under light microscopy, beta I-PKC immunoreactivities seen at birth were the most intense in the brainstem and intense in the diagonal bundle and globus pallidus. beta I-PKC immunoreactivities in these neurons weakened from day 7 and disappeared in the adult brain, while in the cerebral cortex, triangular septal nucleus and pontine nucleus beta I-PKC immunoreactivities were week at birth and then gradually increased. beta II-PKC immunoreactivities were first visible in neurons on day 7 and increased progressively. beta I- and beta II-PKCs were not co-localized in a neuron, as far as examined. The immunoreactivities of beta I-PKC at birth were localized in growth cone-like structures as well as in the dendrites and perikarya. Similarly, alpha-PKC was also present at birth in the growth cone-like structure. Immunoblot analysis revealed that beta I-PKC was present at birth in the growth cone-rich fraction from the hindbrain but not in that from the forebrain, while alpha-PKC was found in the growth cone-rich fraction from both the forebrain and the hindbrain. beta II- and gamma-PKC were not detected in the growth cone-rich fraction from either forebrain or hindbrain. These findings suggest that beta I- and beta II-PKC play a role in different stages of development and in different neurons; both beta-subspecies may be involved in postnatal developing neuronal functions while only beta I-PKC plays functional roles in the growth cone, in the prenatal developmental stage.  相似文献   
12.
13.
14.
The expression and localization of a novel protein kinase C delta (nPKC delta) mRNA were investigated using Northern blotting and in situ hybridization in the developmental process of mouse brain. In adult mice, nPKC delta was abundantly expressed in the thalamus, moderately in the pons and the cerebellum, but faintly in the cerebral cortex and the spinal cord. By in situ hybridization, the signals were observed specifically at the sensory and motor relay nuclei of the thalamus, the dorsal cochlear nuclei of the pons, and the molecular layer of the cerebellum. When developmental changes in the expression of nPKC delta gene were analyzed by in situ hybridization, it was not detectable in embryonic and neonatal brains, very weakly expressed in the thalamus in the first week, and highly expressed at two weeks of age. These results suggest that the gene expression of nPKC delta is strictly controlled by both the cell type and the developmental process.  相似文献   
15.
A sensitive enzyme-linked immunosorbent assay (ELISA) was used in a retrospective study of placental alkaline phosphatase (PLAP) levels in serum, cerebrospinal fluid (CSF), and intratumoral cyst fluid in primary intracranial germinoma. The ELISA showed no cross-reactivity with intestinal alkaline phosphatase except in very high concentrations, after samples had been heat-treated. Three patients with germinoma were studied for serum PLAP levels and in all the levels were elevated (3.78, 0.52, and 2.11 IU/liter). Two of the germinoma patients were studied for PLAP levels in the CSF, and both had elevated levels (0.83 and 9.83 IU/liter). The intratumoral cyst fluid in one case of germinoma was tested for PLAP and the level was found to be very high (603 IU/liter). These PLAP levels decreased concomitantly with the reduction in tumor size during irradiation. Serum PLAP levels were measured in 40 control adult male individuals and in the CSF of 20 nonpregnant patients with subarachnoid hemorrhage. The upper normal limits were 0.20 and 0.11 IU/liter in the serum and the CSF, respectively. All PLAP levels measured in the serum of patients with various brain tumors were 0.18 IU/liter or less. This study strongly suggests that PLAP is a clinically useful tumor marker for primary intracranial germinoma.  相似文献   
16.
OBJECTIVE: We present a case of spontaneous ovarian hyperstimulation caused by pituitary gonadotroph macroadenoma, and include a review of the literature. CASE REPORT: A 27-year-old woman presented with irregular menstruation and bilateral multicystic enlargement of the ovaries. Serum estradiol (E(2)) levels were marginally elevated for the follicular phase but within the physiological range. Serum luteinizing hormone (LH) was extremely low, follicle-stimulating hormone (FSH) was normal, and prolactin (PRL) was high. Magnetic resonance imaging disclosed a pituitary macroadenoma. Immunohistochemical examination of the surgically removed adenoma showed intense reactivity for FSH and LH. After the operation, E(2), LH and PRL levels were normalized, the ovaries returned to a normal morphology, and regular menstrual cycles were resumed. CONCLUSION: A review of the literature showed that ovarian hyperstimulation caused by pituitary gonadotroph adenoma is not always accompanied by elevated FSH levels. High PRL and E(2) and low LH were reported in the majority of the cases, but E(2) may stay within the range observed in normal menstrual cycles.  相似文献   
17.
A patient with cerebral deep sinus thrombosis, which was not diagnosed on the first examination, is reported. A 46-year-old woman presented with headache and vomiting. Neurological examination and a brain computed tomography (CT) scan showed no obvious abnormal findings. The patient suffered disturbed consciousness on the day after the examination, and was admitted to our emergency centre. A CT scan and magnetic resonance imaging revealed an ischaemic lesion in the left basal ganglia, suggesting deep sinus occlusion. Anticoagulant therapy was administered. One day after admission, a CT scan showed a haematoma and severe brain swelling in the same region. Cerebral angiography demonstrated a straight sinus occlusion. Intracranial pressure was not controlled with hypothermia, and the patient died 25 days after admission. Review of the initial CT scan revealed subtle, early findings of deep venous thrombosis that were missed on first examination.  相似文献   
18.
We assessed the efficacy and adverse effects of ivermectin for the treatment of chronic strongyloidiasis. Fifty patients were treated with a single dose of ivermectin at approximately 200 μg/kg, and the dose was repeated 2 weeks later. The eradication rate was 96% (48 of 50 patients) at 2 weeks after the first dose and 98% at 2 weeks after the second dose (49 of 50 patients). In the latter cases, no recurrence was noted at the end of the 4-month post-treatment follow-up period. The gastrointestinal symptoms observed most frequently before the treatment were borborygmus, constipation, and diarrhea. These symptoms improved in the majority of patients after the treatment. Side effects, including nausea and vomiting, occurred in 1 patient (2%), but these were mild and transient. Although abnormal values in laboratory tests were observed in 4 patients (8%), they were mild, and no particular clinical care was required. Thus, ivermectin showed an excellent antihelminthic effect, with little toxicity. Our results indicate that a regimen of two single doses of 200 μg/kg ivermectin, given 2 weeks apart, is clinically suitable for the treatment of chronic strongyloidiasis. Received: April 25, 2001 / Accepted: November 16, 2001  相似文献   
19.
A 68-year-old man, who had underwent aortic valve replacement (AVR) with Björk-Shiley disc valve for aortic regurgitation 17 years ago, was transferred to our hospital complaining of facial ruddiness and swelling, without chest or back pain. Preoperative examination revealed DeBakey type II aortic dissection, which caused superior vena cava syndrome (SVC syndrome). Emergent ascending aortic replacement was performed, postoperatively central venous pressure (CVP) decreased from 33 to 9 mmHg, and SVC syndrome was relieved. Painless aortic dissection after AVR, presenting as SVC syndrome, is a rare case, and close follow-up should be performed under consideration of painless aortic dissection late after AVR.  相似文献   
20.
A 34-year-old male presented with central diabetes insipidus accompanied by upbeat nystagmus and cerebellar ataxia. The patient without family history of above began to walk at the age of 2 years. Polyposia and polyuria were noted at the age of about 4 years. Dysbasia developed at the age of about 7 years. From the age of 30, lalopathy appeared together with various clinical symptoms including cataracts, disturbed intelligence, upbeat nystagmus, abnormal ocular movements, ataxic speech, cerebellar ataxia and reduction of the muscle tone of the limbs, and hypotonic polyuria. Abnormal laboratory findings included square wave jerks, upbeat nystagmus, and "bow tie" nystagmus by EOG, atrophy of the cerebellum and the brainstem by CT, a slight prolongation of the P300 latency, and a central diabetes insipidus pattern by water deprivation test and Carter-Robbins tests. There have been occasional reports of diabetes insipidus complicated by cerebellar ataxia, but in no earlier reports has diabetes insipidus been concurrent with abnormal ocular movements such as upbeat nystagmus. A degenerative disease primarily of the posterior lobe of the hypophysis, hypothalamus, cerebellum, and brainstem was suspected.  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