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   1275篇
  免费   43篇
  国内免费   15篇
耳鼻咽喉   3篇
儿科学   5篇
妇产科学   4篇
基础医学   126篇
口腔科学   34篇
临床医学   66篇
内科学   384篇
皮肤病学   33篇
神经病学   82篇
特种医学   84篇
外科学   248篇
综合类   3篇
预防医学   37篇
眼科学   11篇
药学   48篇
肿瘤学   165篇
  2024年   2篇
  2023年   11篇
  2022年   20篇
  2021年   39篇
  2020年   20篇
  2019年   17篇
  2018年   26篇
  2017年   25篇
  2016年   29篇
  2015年   29篇
  2014年   42篇
  2013年   50篇
  2012年   89篇
  2011年   89篇
  2010年   66篇
  2009年   41篇
  2008年   62篇
  2007年   72篇
  2006年   77篇
  2005年   78篇
  2004年   57篇
  2003年   56篇
  2002年   51篇
  2001年   11篇
  2000年   11篇
  1999年   18篇
  1998年   18篇
  1997年   17篇
  1996年   14篇
  1995年   7篇
  1994年   20篇
  1993年   16篇
  1992年   22篇
  1991年   19篇
  1990年   16篇
  1989年   10篇
  1988年   10篇
  1987年   18篇
  1986年   12篇
  1985年   11篇
  1984年   8篇
  1983年   6篇
  1982年   2篇
  1981年   6篇
  1980年   2篇
  1977年   2篇
  1974年   2篇
  1969年   2篇
  1968年   1篇
  1931年   1篇
排序方式: 共有1333条查询结果,搜索用时 15 毫秒
1.
Morning blood pressure is reported to be more closely related to hypertensive organ damages such as left ventricular mass index, microalbuminuria and silent cerebral infarcts, than blood pressure at other times of the day. Morning blood pressure may play an important role in the pathogenesis of hypertensive target organ damage. Increased sympathetic nerve activity is reported to be one of the mechanisms of morning hypertension; however, there are no available data that show whether strict home blood pressure control, especially in the morning period, can reduce target organ damage. The Japan Morning Surge-1 (JMS-1) study includes hypertensive outpatients with elevated morning systolic blood pressure (>or=135 mmHg) as assessed by self-measured blood pressure monitoring at home. All enrolled patients are under stable antihypertensive medication status. Exclusion criteria are arrhythmia, chronic inflammatory disease, and taking alpha-blockers or beta-blockers. The target number of patients to be enrolled in the JMS-1 study is 600, and the aim is to evaluate differences in the markers of hypertensive target organ damage, such as brain natriuretic peptide and the urinary albumin excretion/creatinine ratio. All of the patients are randomized to an experimental group or a control group, with randomization to be carried out by telephone interviews with the patients' physicians. In the experimental group, patients begin taking additional antihypertensive medication just before going to bed. This consists of doxazosin 1 mg/day, which then is increased to 2 mg/day and 4 mg/day, with a beta-blocker added after a 1-month interval until the morning systolic blood pressure is controlled to less than 135 mmHg. Patients in the control group continue the treatment they are receiving at the enrollment for 6 months. Blood pressure levels, adverse effects, and hypertensive target organ damage before and after the study are evaluated. In the JMS-1 study, we will evaluate whether strict morning blood pressure control by sympathetic nervous system blockade using an alpha-blocker, doxazosin, and with the addition of a beta-blocker if needed, can reduce hypertensive target organ damage.  相似文献   
2.
We determined an operational value for the lumped constant to be used in measurements of the local rate of cerebral glucose use (lCMR(glc)) with FDG in normal adult male rats. METHODS: The standard quantitative autoradiographic method was used with 2-deoxy-d-(14)C-glucose ((14)C-DG) and with (14)C-FDG in awake normal adult male rats. Timed arterial blood samples were drawn for 45 min after the bolus and assayed for plasma glucose and (14)C concentrations. At the end of the 45-min experimental period, the rats were killed, and their brains were removed and divided in half sagittally. One hemisphere was immediately frozen and assayed for local (14)C concentrations by quantitative autoradiography; the other was weighed, homogenized in t-octylphenoxypolyethoxyethanol solution, and assayed for (14)C concentrations in the whole brain by liquid scintillation counting. Paired rats (3 pairs), one in each pair receiving (14)C-DG and the other receiving (14)C-FDG, were studied in parallel on the same day. Additional unpaired animals (n = 8) were studied with either (14)C-DG or (14)C-FDG but not in parallel on the same day. To calculate the lCMR(glc) in rats studied with (14)C-FDG, the rate constants for (14)C-FDG were estimated from the (14)C-DG values determined for rats and the (14)C-FDG/(14)C-DG ratios determined for humans. In all of the rats studied with either (14)C-DG or (14)C-FDG, the lCMR(glc) was first calculated in 12 representative brain structures with the lumped constant of 0.48 previously determined for (14)C-DG in rats. The ratio of the lCMR(glc) thus determined with (14)C-FDG to that determined with (14)C-DG for each structure was then multiplied by the lumped constant for (14)C-DG to estimate the lumped constant for (14)C-FDG. The lCMR(glc) and the lumped constant for FDG in the brain as a whole were similarly estimated from the tracer concentrations in the brain homogenates. RESULTS: The mean values for the lumped constant for FDG were found to be 0.71 and 0.70 in the autoradiographic assays and the assays with brain homogenates, respectively. CONCLUSION: The appropriate value for the lumped constant to be used in determinations of the lCMR(glc) in normal adult male rat studies with (18)F-FDG and small-animal PET scanners is 0.71.  相似文献   
3.
A major goal of current human genome-wide studies is to identify the genetic basis of complex disorders. However, the availability of an unbiased, reliable, cost efficient and comprehensive methodology to analyze the entire genome for complex disease association is still largely lacking or problematic. Therefore, we have developed a practical and efficient strategy for whole genome association studies of complex diseases by charting the human genome at 100 kb intervals using a collection of 27,039 microsatellites and the DNA pooling method in three successive genomic screens of independent case-control populations. The final step in our methodology consists of fine mapping of the candidate susceptible DNA regions by single nucleotide polymorphisms (SNPs) analysis. This approach was validated upon application to rheumatoid arthritis, a destructive joint disease affecting up to 1% of the population. A total of 47 candidate regions were identified. The top seven loci, withstanding the most stringent statistical tests, were dissected down to individual genes and/or SNPs on four chromosomes, including the previously known 6p21.3-encoded Major Histocompatibility Complex gene, HLA-DRB1. Hence, microsatellite-based genome-wide association analysis complemented by end stage SNP typing provides a new tool for genetic dissection of multifactorial pathologies including common diseases.  相似文献   
4.
Germline mutations in patients with familial adenomatous polyposis were analyzed by polymerase chain reaction (PCR) amplification of the adenomatous polyposis coli gene. PCR products from heterozygous patients for deletions of this gene formed four distinct bands on polyacrylamide gel electrophoresis. The four fragments were subsequently purified and both strands of each fragment were directly sequenced, using an automated DNA sequencer and the same primers as those for PCR amplification. It was found that the two slower migrating fragments were “bulge” heteroduplexes, while the other two were homoduplexes made up of two wild-type strands and two deletion-mutant strands, respectively. The sites of deletions in the adenomatous polyposis coli gene could be exactly determined in four of the five patients. In an attempt to identify deletion-carriers of familial adenomatous polyposis at the presymptomatic stage, a family study was also carried out, and two children were found to have the same mutations as those of their affected parents. The direct sequencing of heteroduplex fragments generated during PCR amplification is a potentially useful method for detecting mutations of not only the adenomatous polyposis coli gene but also many other genes of genetic diseases. © 1993 Wiley-Liss, Inc.  相似文献   
5.
A 56-year-old Japanese man with a malignant lymphoma of the parotid gland was reported. The tumor was located in the superficial lobe of the parotid gland, and somewhat invaded the surrounding soft tissues, but the regional lymph nodes were not involved. Histologically, the tumor was composed of round cells with plasmacytoid configurations and small lymphocytes. The plasmacytoid cells showed eccentric nuclei with fairly marked irregularities and perinuclear halos. In a large number of tumor cells, a monoclonal cytoplasmic immunoglobulin (CIg), IgG-Kappa type, was demonstrated by the PAP method. Ultrastructurally, some of the tumor cells showed welldeveloped endoplasmic reticulum. From these findings, this tumor was diagnosed as a diffuse B-cell lymphoma, mainly composed of lymphoplasmacytoid cells. And this tumor may bear a similar nature to an extramedullary plasmacytoma of the classical terminology. Malignant lymphoma of the parotid gland is rare but a case with the demonstration of monoclonal CIg is considered very rare. ACT A PATHOL. JPN. 34: 1459–1467, 1984.  相似文献   
6.
This is a case report of a malignant mesenchymoma of the esophagus in a 50?year-old Japanese man. The tumor was a sessile polypoid mass showing a downward invasion limited to the submucosa of the esophagus. Histologically, the lesion contained rhabdomyosarcomatous and osteosarcomatous areas, in addition to an ill-defined fibrosarcomatous element. In contrast with reports of carcinosarcoma up to the present, this tumor lacked any invasive lesion of an epithelial malignancy. The morphogenesis of these tumor groups was discussed from a hamartoblastomatous standpoint. Acta pathol. jpn. 34: 925~933, 1984.  相似文献   
7.
A case of peritoneal maligant mesothelioma in a radiation technologist, who had worked in this field for 34 years, is reported. Histopathologically, a biopsy specimen from the retroperitoneal tumor revealed a biphasic type of malignant mesothelioma. Electron microscopy disclosed that the tumor cells contained prominent microvilli, basal laminae adjacent to the stroma, junctional complexes, desmosomes, tonofilaments, clusters of glycogen granules, welt developed rough endoplasmic reticulum (RER), confronting cisternae showing direct continuity with the RER and membrane-bound granules suggestive of secretory activity. No increased amount of asbestos was detected in autopsied lung material or the peritoneal mesothelioma. The estimated cumulative dose of occupational irradiation was calculated to be about 40 to 50 rad at most. Irradiation was discussed in relation to the etiology of the peritoneal mosothelioma. Acta Pathol Jpn 40: 57–62, 1990.  相似文献   
8.
Twelve autopsied cases with adult T-cell leukemia (ATL) were reviewed clinicopathologically. The prognosis of three cases who had suffered from severe cutaneous lesions was much better than that of the other nine cases with no or negligible cutaneous lesions. The surface marker of leukemic cells from six cases was ordinary inducer/helper phenotype (OKT4+ and 8-), but in one case leukemic cells showed OKT4+ and 8+. In another case, a significant amount of leukemic cell infiltration was found in the thymic cortex. Calcium content in the bone of ATL cases was lower than that of the patients without ATL (control group), and six cases with ATL (50%) were complicated by severe hypercalcemia. Neither adenoma nor hyperplasia of the parathyroid glands was found in any case. In most severely hypercalcemic patients, bone trabeculae were actively absorbed by numerous osteoclasts and partly replaced by fibrous tissues. In two normocalcemic patients, skeletal calcium content was also markedly reduced by osteoporosis, but the activation of osteoclasts was inconspicuous. It was speculated that the manner of bone resorption in ATL cases was diverse and there were some clinicopathological subtypes in ATL from the viewpoints of cutaneous lesions, hypercalcemia, and bone lesions.  相似文献   
9.
A case of melanocytic schwannoma, a rare form of schwannian neoplasm, in the thoracolumbar spinal canal of a 52-year-old man is presented. Histopathologically, the tumor was composed of irregularly interlacing spindle-shaped cells showing cystic degeneration, with occasional pigmented tumor cells. The tumor cells showed a low degree of nuclear pleomorphism without any mitotic figures. These histological features were considered to be consistent with a benign schwannian tumor showing pigmentation. Most of the pigments were considered to be melanin histochemically and immunohistochemically. According to the pathological features of the present tumor and those described previously in the literature, the neoplastic Schwann cells were assumed to have melanogenetic capacity, and the concept of the common neural crest origin of Schwann cells and melanocytes appeared to be demonstrated in the present tumor.  相似文献   
10.
A 56-year-old Japanese man with a malignant lymphoma of the parotid gland was reported. The tumor was located in the superficial lobe of the parotid gland, and somewhat invaded the surrounding soft tissues, but the regional lymph nodes were not involved. Histologically, the tumor was composed of round cells with plasmacytoid configurations and small lymphocytes. The plasmacytoid cells showed eccentric nuclei with fairly marked irregularities and perinuclearr halos. In a large number of tumor cells, a monoclonal cytoplasmic immunoglobulin (CIg), IgG-Kappa type, was demonstrated by the PAP method. Ultrastructurally, some of the tumor cells showed well-developed endoplasmic reticulum. From these findings, this tumor was diagnosed as a diffuse B-cell lymphoma, mainly composed of lymphoplasmacytoid cells. And this tumor may bear a similar nature to an extramedullary plasmacytoma of the classical terminology. Malignant lymphoma of the parotid gland is rare but a case with the demonstration of monoclonal CIg is considered very rare.  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