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   6579篇
  免费   341篇
  国内免费   31篇
耳鼻咽喉   71篇
儿科学   188篇
妇产科学   135篇
基础医学   809篇
口腔科学   138篇
临床医学   500篇
内科学   1374篇
皮肤病学   83篇
神经病学   697篇
特种医学   280篇
外科学   1053篇
综合类   32篇
一般理论   1篇
预防医学   406篇
眼科学   89篇
药学   445篇
中国医学   11篇
肿瘤学   639篇
  2023年   47篇
  2022年   96篇
  2021年   171篇
  2020年   126篇
  2019年   146篇
  2018年   158篇
  2017年   117篇
  2016年   141篇
  2015年   164篇
  2014年   207篇
  2013年   278篇
  2012年   453篇
  2011年   481篇
  2010年   224篇
  2009年   199篇
  2008年   378篇
  2007年   410篇
  2006年   380篇
  2005年   386篇
  2004年   346篇
  2003年   288篇
  2002年   262篇
  2001年   148篇
  2000年   142篇
  1999年   163篇
  1998年   56篇
  1997年   52篇
  1996年   29篇
  1995年   47篇
  1994年   29篇
  1993年   28篇
  1992年   84篇
  1991年   74篇
  1990年   64篇
  1989年   53篇
  1988年   50篇
  1987年   51篇
  1986年   58篇
  1985年   53篇
  1984年   36篇
  1983年   32篇
  1982年   27篇
  1981年   14篇
  1980年   17篇
  1979年   28篇
  1978年   17篇
  1977年   14篇
  1974年   16篇
  1973年   18篇
  1969年   20篇
排序方式: 共有6951条查询结果,搜索用时 28 毫秒
1.
PURPOSE: The purpose to clarify what kind of managerial challenges employees experience regarding organisational justice in hospitals. DESIGN/METHODOLOGY/APPROACH: This exploratory study of 8,971 employees working in 14 hospitals and examines the concept of organisational justice in management with qualitative and quantitative methods. FINDINGS: An inductive content analysis of the comments revealed five integrative frames describing challenges in hospital management at respondents' workplaces. These frames should be regarded as major managerial challenges in hospitals. These findings illustrate important antecedents of organisational justice and suggest that work units tend to share the same perceptions of justice. They also reveal that individually produced comments reflect collective experiences in organisational justice. Further, the results indicate that problems in management and policies are often experienced in a complex way, and people making justice judgements do not separate procedural and interactional factors. RESEARCH LIMITATIONS/IMPLICATIONS: Although the commentators producing qualitative data represented many organisational hierarchy levels, the results should not be generalised to apply to horizontal, informal social relationships. PRACTICAL IMPLICATIONS: This paper gives useful information regarding challenges in human resources management in hospitals. ORIGINALITY/VALUE: The paper suggests that people making fairness judgements do not make a distinction between procedural and interpersonal factors. Instead, they use any information available to judge the righteousness of the management events. This paper serves to guide hospital managers towards a better understanding of the importance of organisational justice and its collective nature.  相似文献   
2.
The association of bone with the metabolic syndrome and its features, visceral fat accumulation or insulin resistance, remains unclear. We determined visceral and subcutaneous fat areas (V and S) by computed tomography on 187 men (28–83 years) and 125 postmenopausal women (46–82 years) with type 2 diabetes. Men whose V was 100 cm2 or more had significantly lower urinary N-terminal cross-linked telopeptide of type-I collagen (p = 0.005), higher femoral neck bone mineral density (FN-BMD) (p = 0.004), and lower prevalence of vertebral fractures (VFs) (p = 0.04) than controls. Fat mass, V, S, and lean body mass positively correlated with FN-BMD in men and with lumbar (L) and FN-BMD in women. When adjusted for weight, these correlations became negative. Urinary C-peptide positively correlated with FN-BMD in both genders. Multivariate logistic regression analysis adjusted for age, height, weight, L-BMD, duration of diabetes, and diabetes therapies identified V in men and urinary C-peptide in women as factors inversely associated with the presence of VFs [odds ratio (OR) = 0.61 per SD increase, p = 0.04, and OR = 0.32, p = 0.01, respectively]. These findings suggest that, of the components of the metabolic syndrome, body fat in gravity and hyperinsulinemia could increase FN-BMD in diabetic subjects. Visceral fat in men and hyperinsulinemia in women may protect against VFs independent of weight, L-BMD, diabetes duration, or therapies.  相似文献   
3.
This article documents a patient with lung carcinoma that produced three oncofetal antigens including alpha-fetoprotein (AFP), carcinoembryonic antigen (CEA), and human chorionic gonadotropin (hCG). Serum AFP, CEA, and hCG-beta-subunit were extremely high--118,000 ng/ml, 133 ng/ml and 0.9 ng/ml, respectively. Immunohistochemical staining of these tumor markers revealed that these proteins were present in different cells. The pattern of lectin affinity electrophoresis of AFP resembled that of hepatocellular carcinoma. Also investigated was the reactivity of serum CEA to monoclonal antibodies against peptide or sugar moieties. Serum CEA values measured by antipeptide monoclonal antibodies were higher than those measured by antisugar monoclonal antibodies. The demonstration of AFP, CEA, and hCG in different tumor cells suggests that three genomes were not reactivated together in a cell, and the lung carcinoma probably consisted of at least three clones of cancer cells with different phenotypes.  相似文献   
4.
Objective: To study tubal patency and fertility outcome of patients with expectantly managed ectopic pregnancy (EP).

Design: A prospective study.

Setting: Department of Obstetrics and Gynecology, Turku University Central Hospital, Turku, Finland.

Patient(s): Thirty patients who wanted to become pregnant again were treated successfully by expectant management of EP.

Intervention(s): Patients were examined with posttreatment hysterosalpingography, and they filled out a questionnaire about their subsequent pregnancies.

Main Outcome Measure(s): Free passage through open lumen showing tubal patency; number of full-term pregnancies and EPs revealing relative rate of subsequent fertility.

Result(s): A free passage through the diseased tube was seen in 93% of the cases (28 of 30). Two of the 24 patients (8.4%) who wanted to become pregnant had an obstruction in the diseased tube. One (4.2%) of them had a normal opposite tube and later had a normal pregnancy. The other (4.2%) had an obstruction in both tubes and subsequently had a repeat EP. One of the 6 patients had an EP (this patient did not want to become pregnant and did not use contraception). However, her posttreatment hysterosalpingography was normal. In total, the subsequent pregnancy rate was 88% (21 of 24), and the rate of repeat EP was 4.2% (1 of 24).

Conclusion(s): Patients who are treated with expectant management have a good long-term fertility outcome. Spontaneous regression of EP does not lead to increased harm or damage to the tube, i.e., the risk for repeat EP is low.  相似文献   

5.
The matrix metalloproteinase matrilysin (MMP-7) is a member of the matrix metallo-proteinase gene family, which is believed to play an important role in tumor invasion and metastasis. We have previously found that matrilysin mRNA is specifically expressed in colorectal cancers and adenomas and that its message is localized in the tumor cells themselves. We examined the effects of activated Ki-ras oncogene on the expression of matrilysin in colon cancer cells. We showed that both mRNA and the enzymatic activity of matrilysin were induced by the introduction of activated Ki-ras into SW1417 colon cancer cells. To understand the mechanisms regulating this induction, we analyzed alterations of AP-1 activity induced by activated Ki-ras, using the chloramphenicol acetyltransferase assay. AP-1 activity in SW1417 cells expressing activated Ki-ras was higher than that in control cells. The gel-shift assay also showed higher levels of AP-1 binding protein in SW1417 cells expressing activated Ki-ras than those in control cells. Our results suggest that activated Ki-ras may play a role in inducing expression of matrilysin through an AP-1-dependent pathway in colon cancer cells.  相似文献   
6.
We report a case of granulocyte-colony stimulating factor producing gastric cancer with multiple liver metastases. A 68-year-old woman who complained of epigastralgia visited our hospital. Upper gastrointestinal endoscopic examination revealed a type-2 gastric cancer. The laboratory data at admission indicated leukocytosis (35,900/microl) and a high level of serum granulocyte-colony stimulating factor (61 pg/mg). Granulocyte-colony stimulating factor producing gastric cancer was diagnosed by immunohistochemistry of biopsy specimen. Since we detected multiple liver metastases, chemotherapy was performed. Granulocyte-colony stimulating factor-producing gastric cancer is relatively rare and we summarize previous reports.  相似文献   
7.
To elucidate the significance of angiotensin II (AID-induced hypertension chemotherapy, changes of tissue blood flow both in normal subcutis and in tumors (AH109A, LY80) were measured with the hydrogen gas clearance method. A newly-developed anesthetic machine was used to keep the animals' condition constant. Tissue blood flow in normal subcutis and tumors always fluctuated with time under normotension. The nature and the rate of fluctuation in tumor Wood flow were almost identical in two different types of tumors. However, the fluctuation of blood flow in tumor and that in normal subcutis were almost always inversely related when blood flows in these different tissues were measured simultaneously, i.e., when tissue blood flow in normal subcutis decreased, tumor blood flow increased, and vice versa. The findings supported the idea that the connection mode between the tumor vascular bed and normal vascular bed is a parallel circuit. Vascular resistance in the normal vascular bed under All-induced hypertension seemed to be greater than that under normotension, because the All-increased tumor blood flow always exceeded the maximum tumor blood flow under normotension. Due to the fluctuations of tumor blood flow, no-flow or low-flow areas, resistant to delivery of anti-cancer drugs, moved sporadically within the tumor under the normotensive condition. However, good conditions for drug delivery to tumor tissue were induced by All-induced hypertension.  相似文献   
8.
We have previously reported the production of endothelin, a potent vasoconstrictor peptide, by porcine cerebral microvessel endothelia and suggested its important role in the regulation of local blood flow within the brain. In our present study, radioimmunoassay with anti-porcine endothelin antiserum revealed that endothelin, produced by cerebral microvessel endothelia grown on a filter, is released mainly to the basement membrane side, not the vascular lumen side. This finding suggests that endothelin constricts arterioles locally where it is produced by endothelia. We also found that cerebral microvessel endothelia produce less endothelin under low oxygen pressure and more endothelin under low carbon dioxide pressure. Our results suggest that endothelin has a role in the regulation of cerebral blood flow in response to oxygen and carbon dioxide pressure.  相似文献   
9.
To elucidate the molecular basis for endocrine tumorigenesis, p53 mutations in human endocrine tumors were analyzed by using polymerase chain reaction-single strand conformation polymorphism. Exons 5 through 10 of the p53 gene were studied in genomic DNAs from 134 primary endocrine tumors and 6 human endocrine cancer-derived cell lines. Mutations were detected and identified in 4 endocrine tumors, including one parathyroid adenoma and three thyroid carcinoma cell lines. The sites of these mutations were in exons 5 (codon 151 and 152) and 7 (codon 248 and 255). In all of three tumor cell lines, but not in a parathyroid adenoma, the normal allele encoding the p53 gene was lost. However, p53 mutations were not found in any other endocrine tumors or cell lines. Based upon these results, we concluded that the p53 gene may play a role in the tumorigenesis of a limited number of parathyroid adenoma and thyroid cancers, and that the p53 mutation with an allelic loss of the p53 gene is an important factor in malignant tumorigenesis of the thyroid gland.  相似文献   
10.
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